Gesamtliste aus der Hochschulbibliographie

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Fedorova, Aleksandra; Beliautsou, Viktar; Zimmermann, Armin;
Colored Petri net modelling and evaluation of drone inspection methods for distribution networks. - In: Sensors, ISSN 1424-8220, Bd. 22 (2022), 9, S. 1-20
Adekitan, Aderibigbe Israel;
Improving the computational accuracy of the dynamic electro-geometrical model using numerical solutions. - In: Scientific reports, ISSN 2045-2322, Bd. 12 (2022), 5742, S. 1-13

The dynamic electro-geometrical model has been applied in various studies to investigate the probability of a lightning strike to parts of a structure. The numerical computation of the dynamic electro-geometrical model (DEGM) follows an iterative step by determining lightning strike points from above to a point on a structure of interest. This computation is often time-consuming and requires extensive computational resources. This study delves into the inner workings of DEGM striking distance computation. It highlights sources of computational numerical errors, such as the effect of the discretisation size. It proposes ways to eliminate such by using a conversion factor while also significantly reducing computation time from more than 14 h to approximately 6 min for a cuboid structure by eliminating ground surface points. The performance of the proposed improved DEGM (IDEGM) was investigated using a floating roof tank and a cuboid structure with a central air termination, and an interception efficiency of 61% was achieved. An alternative case using catenary wires with a total lightning interception efficiency of 99.1% was also implemented. The percentage strike probability for the cases considered shows a close approximation to published results, and this confirms the accuracy of the implemented model. The IDEGM has the benefit of generating results with a significantly reduced computation time of just a few minutes as compared to several hours in previous models.
Nozdrenko, Dmytro; Prylutska, Svitlana; Bogutska, Kateryna; Nurishchenko, Natalia Y.; Abramchuk, Olga; Motuziuk, Olexandr; Prylutskyy, Yuriy; Scharff, Peter; Ritter, Uwe;
Effect of C60 fullerene on recovery of muscle soleus in rats after atrophy induced by achillotenotomy. - In: Life, ISSN 2075-1729, Bd. 12 (2022), 3, 332, S. 1-13

Biomechanical and biochemical changes in the muscle soleus of rats during imitation of hind limbs unuse were studied in the model of the Achilles tendon rupture (Achillotenotomy). Oral administration of water-soluble C60 fullerene at a dose of 1 mg/kg was used as a therapeutic agent throughout the experiment. Changes in the force of contraction and the integrated power of the muscle, the time to reach the maximum force response, the mechanics of fatigue processes development, in particular, the transition from dentate to smooth tetanus, as well as the levels of pro- and antioxidant balance in the blood of rats on days 15, 30 and 45 after injury were described. The obtained results indicate a promising prospect for C60 fullerene use as a powerful antioxidant for reducing and correcting pathological conditions of the muscular system arising from skeletal muscle atrophy.
Ispirli, Mehmet Murat; Kalenderli, Özcan; Seifert, Florian; Rock, Michael; Oral, Bülent;
Investigation of impact of DC component on breakdown characteristics for different electric fields under composite AC & DC voltage. - In: High voltage, ISSN 2397-7264, Bd. 7 (2022), 2, S. 279-287
Ispirli, Mehmet Murat; Kalenderli, Özcan; Seifert, Florian; Rock, Michael; Oral, Bülent;
The effect of DC voltage pre-stress on breakdown voltage of air under composite DC & LI voltage and test circuit: design and application. - In: Energies, ISSN 1996-1073, Bd. 15 (2022), 4, 1353, S. 1-23

The use of HVDC systems is increasing in number due to technological innovations, increasing power capacity and increasing customer demand. The characteristics of insulation systems under composite DC and LI voltage must be examined and clarified. In this study, firstly, experimental circuits were designed to generate and measure composite DC and LI high voltage using a simulation program. The coupling elements used were chosen according to simulation results. Afterward, experimental circuits were established in the laboratory according to the simulation results of the designed experimental circuit. Then, breakdown voltages under composite DC and LI voltage for less uniform and non-uniform electric fields were measured with four different electrode systems for positive and negative DC voltage pre-stresses with different amplitudes. The 50% breakdown voltage was calculated using the least-squares method. Finally, 3D models were created for the electrode systems used in the experiments using the finite element method. The efficiency factors of electrode systems calculated with the FEM results were correlated with the experimental breakdown voltage results. Thus, the breakdown behavior of air under bipolar and unipolar composite voltages (CV) was investigated. In conclusion, the experimental results showed that very fast polarity change in bipolar CV causes higher electrical stress compared to unipolar CV.
Wagner, Christoph; Semper, Sebastian; Kirchhof, Jan;
fastmat: efficient linear transforms in Python. - In: SoftwareX, ISSN 2352-7110, Bd. 18 (2022), 101013, S. 1-8

Scientific computing requires handling large linear models, which are often composed of structured matrices. With increasing model size, dense representations quickly become infeasible to compute or store. Matrix-free implementations are suited to mitigate this problem at the expense of additional implementation overhead, which complicates research and development effort by months, when applied to practical research problems. Fastmat is a framework for handling large structured matrices by offering an easy-to-use abstraction model. It allows for the expression of matrix-free linear operators in a mathematically intuitive way, while retaining their benefits in computation performance and memory efficiency. A built-in hierarchical unit-test system boosts debugging productivity and run-time execution path optimization improves the performance of highly-structured operators. The architecture is completed with an interface for abstractly describing algorithms that apply such matrix-free linear operators, while maintaining clear separation of their respective implementation levels. Fastmat achieves establishing a close relationship between implementation code and the actual mathematical notation of a given problem, promoting readable, portable and re-usable scientific code.
Dittrich, Paul-Gerald; Kraus, Daniel; Ehrhardt, Enrico; Henkel, Thomas; Notni, Gunther;
Multispectral imaging flow cytometry with spatially and spectrally resolving snapshot-mosaic cameras for the characterization and classification of bioparticles. - In: Micromachines, ISSN 2072-666X, Bd. 13 (2022), 2, 238, S. 1-12
Zahn, Diana; Landers, Joachim; Buchwald, Juliana; Diegel, Marco; Salamon, Soma; Müller, Robert; Köhler, Moritz; Ecke, Gernot; Wende, Heiko; Dutz, Silvio;
Ferrimagnetic large single domain iron oxide nanoparticles for hyperthermia applications. - In: Nanomaterials, ISSN 2079-4991, Bd. 12 (2022), 3, 343, S. 1-12

This paper describes the preparation and obtained magnetic properties of large single domain iron oxide nanoparticles. Such ferrimagnetic particles are particularly interesting for diagnostic and therapeutic applications in medicine or (bio)technology. The particles were prepared by a modified oxidation method of non-magnetic precursors following the green rust synthesis and characterized regarding their structural and magnetic properties. For increasing preparation temperatures (5 to 85 ˚C), an increasing particle size in the range of 30 to 60 nm is observed. Magnetic measurements confirm a single domain ferrimagnetic behavior with a mean saturation magnetization of ca. 90 Am2/kg and a size-dependent coercivity in the range of 6 to 15 kA/m. The samples show a specific absorption rate (SAR) of up to 600 W/g, which is promising for magnetic hyperthermia application. For particle preparation temperatures above 45 ˚C, a non-magnetic impurity phase occurs besides the magnetic iron oxides that results in a reduced net saturation magnetization.
Gholamhosseinian, Ashkan; Seitz, Jochen;
A comprehensive survey on cooperative intersection management for heterogeneous connected vehicles. - In: IEEE access, ISSN 2169-3536, Bd. 10 (2022), S. 7937-7972
Eichfelder, Gabriele; Groetzner, Patrick;
A note on completely positive relaxations of quadratic problems in a multiobjective framework. - In: Journal of global optimization, ISSN 1573-2916, Bd. 82 (2022), 3, S. 615-626

In a single-objective setting, nonconvex quadratic problems can equivalently be reformulated as convex problems over the cone of completely positive matrices. In small dimensions this cone equals the cone of matrices which are entrywise nonnegative and positive semidefinite, so the convex reformulation can be solved via SDP solvers. Considering multiobjective nonconvex quadratic problems, naturally the question arises, whether the advantage of convex reformulations extends to the multicriteria framework. In this note, we show that this approach only finds the supported nondominated points, which can already be found by using the weighted sum scalarization of the multiobjective quadratic problem, i.e. it is not suitable for multiobjective nonconvex problems.
Voss, Andreas; Schroeder, Rico; Schulz, Steffen; Haueisen, Jens; Vogler, Stefanie; Horn, Paul; Stallmach, Andreas; Reuken, Philipp Alexander;
Detection of liver dysfunction using a wearable electronic nose system based on semiconductor metal oxide sensors. - In: Biosensors, ISSN 2079-6374, Bd. 12 (2022), 2, 70, S. 1-15
Baloochi, Mostafa; Shekhawat, Deepshikha; Riegler, Sascha Sebastian; Matthes, Sebastian; Glaser, Marcus; Schaaf, Peter; Bergmann, Jean Pierre; Gallino, Isabella; Pezoldt, Jörg;
Influence of initial temperature and convective heat loss on the self-propagating reaction in Al/Ni multilayer foils. - In: Materials, ISSN 1996-1944, Bd. 14 (2021), 24, 7815, insges. 15 S.

A two-dimensional numerical model for self-propagating reactions in Al/Ni multilayer foils was developed. It was used to study thermal properties, convective heat loss, and the effect of initial temperature on the self-propagating reaction in Al/Ni multilayer foils. For model adjustments by experimental results, these Al/Ni multilayer foils were fabricated by the magnetron sputtering technique with a 1:1 atomic ratio. Heat of reaction of the fabricated foils was determined employing Differential Scanning Calorimetry (DSC). Self-propagating reaction was initiated by an electrical spark on the surface of the foils. The movement of the reaction front was recorded with a high-speed camera. Activation energy is fitted with these velocity data from the high-speed camera to adjust the numerical model. Calculated reaction front temperature of the self-propagating reaction was compared with the temperature obtained by time-resolved pyrometer measurements. X-ray diffraction results confirmed that all reactants reacted and formed a B2 NiAl phase. Finally, it is predicted that (1) increasing thermal conductivity of the final product increases the reaction front velocity; (2) effect of heat convection losses on reaction characteristics is insignificant, e.g., the foils can maintain their characteristics in water; and (3) with increasing initial temperature of the foils, the reaction front velocity and the reaction temperature increased.
Kutschka, Hermann; Doeller, Christian F.; Haueisen, Jens; Maess, Burkhard;
Magnetic field compensation coil design for magnetoencephalography. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 22650, insges. 12 S.

While optically pumped magnetometers (OPMs) can be attached to the head of a person and allow for highly sensitive recordings of the human magnetoencephalogram (MEG), they are mostly limited to an operational range of approximately 5 nT. Consequently, even inside a magnetically shielded room (MSR), movements in the remnant magnetic field disable the OPMs. Active suppression of the remnant field utilizing compensation coils is therefore essential. We propose 8 compensation coils on 5 sides of a cube with a side length of approximately 2 m which were optimized for operation inside an MSR. Compared to previously built bi-planar compensation coils, the coils proposed in this report are more complex in geometry and achieved smaller errors for simulated compensation fields. The proposed coils will allow for larger head movements or smaller movement artifacts in future MEG experiments compared to existing coils.
Eichfelder, Gabriele; Warnow, Leo;
An approximation algorithm for multi-objective optimization problems using a box-coverage. - In: Journal of global optimization, ISSN 1573-2916, (2021), insges. 29 S.

For a continuous multi-objective optimization problem, it is usually not a practical approach to compute all its nondominated points because there are infinitely many of them. For this reason, a typical approach is to compute an approximation of the nondominated set. A common technique for this approach is to generate a polyhedron which contains the nondominated set. However, often these approximations are used for further evaluations. For those applications a polyhedron is a structure that is not easy to handle. In this paper, we introduce an approximation with a simpler structure respecting the natural ordering. In particular, we compute a box-coverage of the nondominated set. To do so, we use an approach that, in general, allows us to update not only one but several boxes whenever a new nondominated point is found. The algorithm is guaranteed to stop with a finite number of boxes, each being sufficiently thin.
Dashtestani, Ashkan Djaberi; Moeinian, Ardeshir; Biskupek, Johannes; Strehle, Steffen;
Contamination-assisted rather than metal catalyst-free bottom-up growth of silicon nanowires. - In: Advanced materials interfaces, ISSN 2196-7350, Bd. 8 (2021), 22, 2101121, insges. 9 S.

Well-established metal-catalyzed vapor-liquid-solid (VLS) growth represents still undoubtedly the key technology for bottom-up synthesis of single-crystalline silicon nanowires (SiNWs). Although various SiNW applications are demonstrated, electrical and optical properties are exposed to the inherent risk of electronic deep trap state formation by metal impurities. Therefore, metal catalyst-free growth strategies are intriguing. The oxid-assisted SiNW synthesis is explored and it is shown that contamination control is absolutely crucial. Slightest metal impurities, such as iron, are sufficient to trigger SiNW growth, calling into question true metal catalyst-free SiNW synthesis. Therefore, the term contamination-assisted is rather introduced and it is shown that contamination-assisted SiNW growth is determined by the chemical surface treatment (e.g., with KOH solution), but also by the crystal orientation of a silicon substrate. SiNWs are grown in this regards in a reproducible manner, but so far with a distinct tapering, using a conventional gas-phase reactor system at temperatures of about 680 ˚C and monosilane (SiH4) as the precursor gas. The synthesized SiNWs show convincing electrical properties compared to Au-catalyzed SiNWs. Nevertheless, contamination-assisted growth of SiNWs appears to be an important step toward bottom-up synthesis of high-quality SiNWs with a lower risk of metal poisoning, such as those needed for CMOS and other technologies.
Steinmetz, Nadine; Sattler, Kai-Uwe;
What is in the KGQA benchmark datasets? Survey on challenges in datasets for question answering on knowledge graphs. - In: Journal on data semantics, ISSN 1861-2040, Bd. 10 (2021), 3/4, S. 241-265

Question Answering based on Knowledge Graphs (KGQA) still faces difficult challenges when transforming natural language (NL) to SPARQL queries. Simple questions only referring to one triple are answerable by most QA systems, but more complex questions requiring complex queries containing subqueries or several functions are still a tough challenge within this field of research. Evaluation results of QA systems therefore also might depend on the benchmark dataset the system has been tested on. For the purpose to give an overview and reveal specific characteristics, we examined currently available KGQA datasets regarding several challenging aspects. This paper presents a detailed look into the datasets and compares them in terms of challenges a KGQA system is facing.
Sha, Mo; Zhao, Huaping; Lei, Yong;
Updated insights into 3D architecture electrodes for micropower sources. - In: Advanced materials, ISSN 1521-4095, Bd. 33 (2021), 45, 2103304, insges. 17 S.

Microbatteries (MBs) and microsupercapacitors (MSCs) are primary on-chip micropower sources that drive autonomous and stand-alone microelectronic devices for implementation of the Internet of Things (IoT). However, the performance of conventional MBs and MSCs is restricted by their 2D thin-film electrode design, and these devices struggle to satisfy the increasing IoT energy demands for high energy density, high power density, and long lifespan. The energy densities of MBs and MSCs can be improved significantly through adoption of a 2D thick-film electrode design; however, their power densities and lifespans deteriorate with increased electrode thickness. In contrast, 3D architecture electrodes offer remarkable opportunities to simultaneously improve MB and MSC energy density, power density, and lifespan. To date, various 3D architecture electrodes have been designed, fabricated, and investigated for MBs and MSCs. This review provides an update on the principal superiorities of 3D architecture electrodes over 2D thick-film electrodes in the context of improved MB and MSC energy density, power density, and lifespan. In addition, the most recent and representative progress in 3D architecture electrode development for MBs and MSCs is highlighted. Finally, present challenges are discussed and key perspectives for future research in this field are outlined.
Krauß, Benedikt; Link, Dietmar; Stodtmeister, Richard; Nagel, Edgar; Vilser, Walthard; Klee, Sascha;
Modulation of human intraocular pressure using a pneumatic system. - In: Translational Vision Science & Technology, ISSN 2164-2591, Bd. 10 (2021), 14, 4, S. 1-9
Löffelholz, Martin;
[Rezension von: Meyen, Michael, 1967-, Das Erbe sind wir]. - In: Publizistik. - Wiesbaden : VS Verl. für Sozialwiss., 2000- , ISSN: 1862-2569 , ZDB-ID: 2273951-8, ISSN 1862-2569, Bd. 66 (2021), 3/4, S. 673-675
Döring, Nicola; Conde, Melisa;
Sexual health information on social media: a systematic scoping review :
Sexuelle Gesundheitsinformationen in sozialen Medien: ein systematisches Scoping Review. - In: Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz, ISSN 1437-1588, Bd. 64 (2021), 11, S. 1416-1429
Vasconcelos, Beatriz; Fiedler, Patrique; Machts, René; Haueisen, Jens; Fonseca, Carlos;
The Arch electrode: a novel dry electrode concept for improved wearing comfort. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 15 (2021), 748100, S. 1-14
Derkach, Volodymyr; Strelnikov, Dmytro; Winkler, Henrik;
On a class of integral systems. - In: Complex analysis and operator theory, ISSN 1661-8262, Bd. 15 (2021), 6, 103, insges. 39 S.

We study spectral problems for two-dimensional integral system with two given non-decreasing functions R, W on an interval [0, b) which is a generalization of the Krein string. Associated to this system are the maximal linear relation Tmax and the minimal linear relation Tmin in the space L2(dW) which are connected by Tmax=T*min. It is shown that the limit point condition at b for this system is equivalent to the strong limit point condition for the linear relation Tmax. In the limit circle case the Evans-Everitt condition is proved to hold on a subspace T*N of Tmax characterized by the Neumann boundary condition at b. The notion of the principal Titchmarsh-Weyl coefficient of this integral system is introduced. Boundary triple for the linear relation Tmax in the limit point case (and for T*N in the limit circle case) is constructed and it is shown that the corresponding Weyl function coincides with the principal Titchmarsh-Weyl coefficient of the integral system. The notion of the dual integral system is introduced by reversing the order of R and W and the formula relating the principal Titchmarsh-Weyl coefficients of the direct and the dual integral systems is proved. For every integral system with the principal Titchmarsh-Weyl coefficients q a canonical system is constructed so that its Titchmarsh-Weyl coefficient Q is the unwrapping transform of q: Q(z)=zq(z2).
Hurmach, Vasyl V.; Platonov, Maksim O.; Prylutska, Svitlana V.; Scharff, Peter; Prylutskyy, Yuriy I.; Ritter, Uwe;
C60 fullerene against SARS-CoV-2 coronavirus: an in silico insight. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 17748, insges. 12 S.
Im Titel ist "60" tiefgestellt

Based on WHO reports the new SARS-CoV-2 coronavirus is currently widespread all over the world. So far > 162 million cases have been confirmed, including > 3 million deaths. Because of the pandemic still spreading across the globe the accomplishment of computational methods to find new potential mechanisms of virus inhibitions is necessary. According to the fact that C60 fullerene (a sphere-shaped molecule consisting of carbon) has shown inhibitory activity against various protein targets, here the analysis of the potential binding mechanism between SARS-CoV-2 proteins 3CLpro and RdRp with C60 fullerene was done; it has resulted in one and two possible binding mechanisms, respectively. In the case of 3CLpro, C60 fullerene interacts in the catalytic binding pocket. And for RdRp in the first model C60 fullerene blocks RNA synthesis pore and in the second one it prevents binding with Nsp8 co-factor (without this complex formation, RdRp can't perform its initial functions). Then the molecular dynamics simulation confirmed the stability of created complexes. The obtained results might be a basis for other computational studies of 3CLPro and RdRp potential inhibition ways as well as the potential usage of C60 fullerene in the fight against COVID-19 disease.
Blum, Maren-Christina; Hunold, Alexander; Solf, Benjamin; Klee, Sascha;
Ocular direct current stimulation affects retinal ganglion cells. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 17573, insges. 9 S.

Ocular current stimulation (oCS) with weak current intensities (a few mA) has shown positive effects on retinal nerve cells, which indicates that neurodegenerative ocular diseases could be treated with current stimulation of the eye. During oCS, a significant polarity-independent reduction in the characteristic P50 amplitude of a pattern-reversal electroretinogram was found, while no current stimulation effect was found for a full field electroretinogram (ffERG). The ffERG data indicated a trend for a polarity-dependent influence during oCS on the photopic negative response (PhNR) wave, which represents the sum activity of the retinal ganglion cells. Therefore, an ffERG with adjusted parameters for the standardized measurement of the PhNR wave was combined with simultaneous oCS to study the potential effects of direct oCS on cumulative ganglion cell activity. Compared with that measured before oCS, the PhNR amplitude in the cathodal group increased significantly during current stimulation, while in the anodal and sham groups, no effect was visible (α = 0.05, pcathodal = 0.006*). Furthermore, repeated-measures ANOVA revealed a significant difference in PhNR amplitude between the anodal and cathodal groups as well as between the cathodal and sham groups (p* ≤ 0.0167, pcathodal - anodal = 0.002*, pcathodal - sham = 0.011*).
Ley, Sebastian; Sachs, Jürgen; Faenger, Bernd; Hilger, Ingrid; Helbig, Marko;
MNP-enhanced microwave medical imaging by means of pseudo-noise sensing. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 19, 6613, insges. 23 S.
Grätzel, Michael; Sieber, Felix; Schick-Witte, Konstantin; Bergmann, Jean Pierre;
Advances in friction stir welding by separate control of shoulder and probe. - In: Welding in the world, ISSN 1878-6669, Bd. 65 (2021), 10, S. 1931-1941

Friction stir welding (FSW) has developed into a reliable and increasing used industrial joining technology. Various tool configurations can be used for FSW, each of which has advantages and challenges. State-of-the-art FSW employs various tool configurations, including the conventional, the stationary shoulder, and the dual-rotational configuration which is characterized by separate control of shoulder and probe. In this study, an innovative method to combine various tool configurations was developed by a novel FSW spindle stack construction. With an additional servomotor, existing FSW systems can be extended by separate control of shoulder and probe so that varying rotational speeds and rotational directions can be set. This allows enhanced possibilities (a) to adjust frictional heat generation and (b) to apply several tool configurations. The main advantages of this enhanced type of FSW are demonstrated in three ways: increased weld penetration depth, reduction of undesirable machine vibrations, and the combination of varying tool configurations such as stationary shoulder and conventional FSW. The investigations were carried out with 2-mm EN AA 5754 H22 sheets and performed on a robotized FSW setup.
Kronfeld, Klaus-Peter; Ellinger, Thomas; Köhler, Michael;
Micro flow photochemical synthesis of Ca-sensitive fluorescent sensor particles. - In: Engineering in life sciences, ISSN 1618-2863, Bd. 21 (2021), 8/9, S. 518-526

Fluorescence probes have widely been used for detecting and imaging Ca2+-enriched parts of cells but more rarely for quantitative determination of concentrations. In this study we show how this can be achieved by a novel approach using hydrogel particles. In a microfluidic co-flow arrangement spherical droplets were generated from an aqueous solution of acrylamide, N,N'-methylenebisacrylamide crosslinker and photoinitiator and subsequently photo-cured in situ yielding gel particles in a sub millimeter range. These particles were separated, dried under reduced pressure and re-swollen in water containing Rhod-5N tri potassium salt as calcium ion selective fluorescence probe. After that the particles were dried again and stored for further investigations. Upon exposure of dried particles to calcium chloride solutions they swell and take up Ca2+-ions forming a strong fluorescing complex with Rhod-5N. Thus, fluorescence intensity increases with calcium ion concentration. Up to ca. 0.50 mM the enhancement effect is strong and then becomes considerably weaker. The intensity-concentration-dependence is well described by an equation derived from the equilibrium of the formation of a 1:1 Ca2+:Rhod-5N complex. The particles allow for a fast optical determination of Ca2+-concentrations up to 0.50 mM in analyte volumes down to below 10 [my]L.
Manske, Eberhard; Theska, René; Fröhlich, Thomas; Ortlepp, Ingo;
Foreword to the special issue on "Tip- and laser-based 3D nanofabrication in extended macroscopic working areas". - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 131
Kläbe, Steffen; Sattler, Kai-Uwe; Baumann, Stephan;
PatchIndex: exploiting approximate constraints in distributed databases. - In: Distributed and parallel databases, ISSN 1573-7578, Bd. 39 (2021), 3, S. 833-853

Cloud data warehouse systems lower the barrier to access data analytics. These applications often lack a database administrator and integrate data from various sources, potentially leading to data not satisfying strict constraints. Automatic schema optimization in self-managing databases is difficult in these environments without prior data cleaning steps. In this paper, we focus on constraint discovery as a subtask of schema optimization. Perfect constraints might not exist in these unclean datasets due to a small set of values violating the constraints. Therefore, we introduce the concept of a generic PatchIndex structure, which handles exceptions to given constraints and enables database systems to define these approximate constraints. We apply the concept to the environment of distributed databases, providing parallel index creation approaches and optimization techniques for parallel queries using PatchIndexes. Furthermore, we describe heuristics for automatic discovery of PatchIndex candidate columns and prove the performance benefit of using PatchIndexes in our evaluation.
Budzinski, Oliver; Gänßle, Sophia; Lindstädt-Dreusicke, Nadine;
The battle of YouTube, TV and Netflix: an empirical analysis of competition in audiovisual media markets. - In: SN business & economics, ISSN 2662-9399, Bd. 1 (2021), 9, 116, insges. 26 S.

The world of audiovisual online markets is rapidly changing. Not long ago, it was dominated by linear television, transmitted terrestrially, through cable networks or via satellite. Recently, streaming services such as Netflix, YouTube, Amazon Prime and others have emerged as new suppliers of audiovisual content. In this quickly changing industry, competition interrelations between such different formats such as traditional TV, videos on YouTube, and streaming via Netflix are subject to controversy. In particular, doubt is cast on services such as YouTube exerting competitive pressure on services such as Netflix and traditional TV. Based upon a survey with 2920 participants, we provide an empirical analysis of consumption behavior of audiovisual contents. Using descriptive and analytical statistics, including multiple equation models, we show that there are specific areas within audiovisual content markets, where YouTube exerts considerable competitive pressure on both Netflix and classic TV, for instance, through prime time video entertainment. However, our analysis yields differentiated results as we also identify areas, where competition intensity between different service types appear to be low, for instance, through daytime and regarding the intention to shorten waiting time.
Mehler, Alexander; Néel, Nicolas; Voloshina, Elena; Dedkov, Yuriy; Kröger, Jörg;
Second floor of flatland: epitaxial growth of graphene on hexagonal boron nitride. - In: Small, ISSN 1613-6829, Bd. 17 (2021), 36, 2102747, insges. 9 S.

In the studies presented here, the subsequent growth of graphene on hexagonal boron nitride (h-BN) is achieved by the thermal decomposition of molecular precursors and the catalytic assistance of metal substrates. The epitaxial growth of h-BN on Pt(111) is followed by the deposition of a temporary Pt film that acts as a catalyst for the fabrication of the graphene sheet. After intercalation of the intermediate Pt film underneath the boron-nitride mesh, graphene resides on top of h-BN. Scanning tunneling microscopy and density functional calculations reveal that the moiré pattern of the van-der-Waals-coupled double layer is due to the interface of h-BN and Pt(111). While on Pt(111) the graphene honeycomb unit cells uniformly appear as depressions using a clean metal tip for imaging, on h-BN they are arranged in a honeycomb lattice where six protruding unit cells enframe a topographically dark cell. This superstructure is most clearly observed at small probe-surface distances. Spatially resolved inelastic electron tunneling spectroscopy enables the detection of a previously predicted acoustic hybrid phonon of the stacked materials. Its' spectroscopic signature is visible in surface regions where the single graphene sheet on Pt(111) transitions into the top layer of the stacking.
Ilchmann, Achim; Kirchhoff, Jonas;
Differential-algebraic systems are generically controllable and stabilizable. - In: Mathematics of control, signals, and systems, ISSN 1435-568X, Bd. 33 (2021), 3, S. 359-377

We investigate genericity of various controllability and stabilizability concepts of linear, time-invariant differential-algebraic systems. Based on well-known algebraic characterizations of these concepts (see the survey article by Berger and Reis (in: Ilchmann A, Reis T (eds) Surveys in differential-algebraic equations I, Differential-Algebraic Equations Forum, Springer, Berlin, pp 1-61., we use tools from algebraic geometry to characterize genericity of controllability and stabilizability in terms of matrix formats.
Scheidig, Andrea; Schütz, Benjamin; Trinh, Thanh Quang; Vorndran, Alexander; Mayfarth, Anke; Sternitzke, Christian; Röhner, Eric; Groß, Horst-Michael;
Robot-assisted gait self-training: assessing the level achieved. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 18, 6213, insges. 15 S.

This paper presents the technological status of robot-assisted gait self-training under real clinical environment conditions. A successful rehabilitation after surgery in hip endoprosthetics comprises self-training of the lessons taught by physiotherapists. While doing this, immediate feedback to the patient about deviations from the expected physiological gait pattern during training is important. Hence, the Socially Assistive Robot (SAR) developed for this type of training employs task-specific, user-centered navigation and autonomous, real-time gait feature classification techniques to enrich the self-training through companionship and timely corrective feedback. The evaluation of the system took place during user tests in a hospital from the point of view of technical benchmarking, considering the therapists' and patients' point of view with regard to training motivation and from the point of view of initial findings on medical efficacy as a prerequisite from an economic perspective. In this paper, the following research questions were primarily considered: Does the level of technology achieved enable autonomous use in everyday clinical practice? Has the gait pattern of patients who used additional robot-assisted gait self-training for several days been changed or improved compared to patients without this training? How does the use of a SAR-based self-training robot affect the motivation of the patients?
Hirth, Matthias; Seufert, Michael; Lange, Stanislav; Meixner, Markus; Tran-Gia, Phuoc;
Performance evaluation of hybrid crowdsensing and fixed sensor systems for event detection in urban environments. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 17, 5880, insges. 18 S.

Crowdsensing offers a cost-effective way to collect large amounts of environmental sensor data; however, the spatial distribution of crowdsensing sensors can hardly be influenced, as the participants carry the sensors, and, additionally, the quality of the crowdsensed data can vary significantly. Hybrid systems that use mobile users in conjunction with fixed sensors might help to overcome these limitations, as such systems allow assessing the quality of the submitted crowdsensed data and provide sensor values where no crowdsensing data are typically available. In this work, we first used a simulation study to analyze a simple crowdsensing system concerning the detection performance of spatial events to highlight the potential and limitations of a pure crowdsourcing system. The results indicate that even if only a small share of inhabitants participate in crowdsensing, events that have locations correlated with the population density can be easily and quickly detected using such a system. On the contrary, events with uniformly randomly distributed locations are much harder to detect using a simple crowdsensing-based approach. A second evaluation shows that hybrid systems improve the detection probability and time. Finally, we illustrate how to compute the minimum number of fixed sensors for the given detection time thresholds in our exemplary scenario.
Zhang, Yan; Müller, Steffen; Stephan, Benedict; Groß, Horst-Michael; Notni, Gunther;
Point cloud hand-object segmentation using multimodal imaging with thermal and color data for safe robotic object handover. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 16, 5676, insges. 16 S.
Žuraulis, Vidas; Sivilevičius, Henrikas; Šabanovič, Eldar; Ivanov, Valentin; Skrickij, Viktor;
Variability of gravel pavement roughness: an analysis of the impact on vehicle dynamic response and driving comfort. - In: Applied Sciences, ISSN 2076-3417, Bd. 11 (2021), 16, 7582, insges. 18 S.

Gravel pavement has lower construction costs but poorer performance than asphalt surfaces on roads. It also emits dust and deforms under the impact of vehicle loads and ambient air factors; the resulting ripples and ruts constantly deepen, and therefore increase vehicle vibrations and fuel consumption, and reduce safe driving speed and comfort. In this study, existing pavement quality evaluation indexes are analysed, and a methodology for adapting them for roads with gravel pavement is proposed. We report the measured wave depth and length of gravel pavement profile using the straightedge method on a 160 m long road section at three stages of road utilization. The measured pavement elevation was processed according to ISO 8608, and the frequency response of a vehicle was investigated using simulations in MATLAB/Simulink. The international roughness index (IRI) analysis showed that a speed of 30-45 km/h instead of 80 km/h provided the objective results of the IRI calculation on the flexible pavement due to the decreasing velocity of a vehicles unsprung mass on a more deteriorated road pavement state. The influence of the corrugation phenomenon of gravel pavement was explored, identifying specific driving safety and comfort cases. Finally, an increase in the dynamic load coefficient (DLC) at a low speed of 30 km/h on the most deteriorated pavement and a high speed of 90 km/h on the middle-quality pavement demonstrated the demand for timely gravel pavement maintenance and the complicated prediction of a safe driving speed for drivers. The main relevant objectives of this study are the adaptation of a road roughness indicator to gravel pavement, including the evaluation of vehicle dynamic responses at different speeds and pavement deterioration states.
Cretu, Andrea; Mattea, Carlos; Stapf, Siegfried;
Low-field and variable-field NMR relaxation studies of H2O and D2O molecular dynamics in articular cartilage. - In: PLOS ONE, ISSN 1932-6203, Bd. 16 (2021), 8, e0256177, insges. 34 S.
Im Titel ist "2" tiefgestellt
Supreeti, Shraddha; Schienbein, Ralf; Feßer, Patrick; Fern, Florian; Hoffmann, Martin; Sinzinger, Stefan;
Development and implementation of a rotating nanoimprint lithography tool for orthogonal imprinting on edges of curved surfaces. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 175-180

Uniform molding and demolding of structures on highly curved surfaces through conformal contact is a crucial yet often-overlooked aspect of nanoimprint lithography (NIL). This study describes the development of a NIL tool and its integration into a nanopositioning and nanomeasuring machine to achieve high-precision orthogonal molding and demolding for soft ultraviolet-assisted NIL (soft UV-NIL). The process was implemented primarily on the edges of highly curved plano-convex substrates to demonstrate structure uniformity on the edges. High-resolution nanostructures of sub-200-nm lateral dimension and microstructures in the range of tens of microns were imprinted. However, the nanostructures on the edges of the large, curved substrates were difficult to characterize precisely. Therefore, microstructures were used to measure the structure fidelity and were characterized using profilometry, white light interferometry, and confocal laser scanning microscopy. Regardless of the restricted imaging capabilities at high inclinations for high-resolution nanostructures, the scanning electron microscope (SEM) imaging of the structures on top of the lens substrate and at an inclination of 45˚ was performed. The micro and nanostructures were successfully imprinted on the edges of the plano-convex lens at angles of 45˚, 60˚,and 90˚ from the center of rotation of the rotating NIL tool. The method enables precise imprinting at high inclinations, thereby presenting a different approach to soft UV-NIL on curved surfaces.
Prem, Nina; Schale, Florian; Zimmermann, Klaus; Gowda, Darshan Kare; Odenbach, Stefan;
Synthesis and characterization of the properties of thermosensitive elastomers with thermoplastic and magnetic particles for application in soft robotics. - In: Journal of applied polymer science, ISSN 1097-4628, Bd. 138 (2021), 44, 51296, insges. 14 S.

In the currently rapidly developing field of soft robots, smart materials with controllable properties play the central role. Thermosensitive elastomers are soft, smart materials whose material properties can be controlled by changing their temperature. The aim of this work is to investigate the mechanical properties, to analyze the surface, the inner structure, and the heat transfer within the thermosensitive elastomer materials. This should provide a knowledge base for new combinations, such as a combination of thermosensitive and the well-known magneto sensitive elastomers, in order to realize new applications. Thermoplastic polycaprolactone particles were incorporated into a flexible polydimethylsiloxane matrix to produce thermosensitive elastomer samples. With a low melting point in the range of 58-60˚C, polycaprolactone offers good application potential compared to other thermoplastic materials such as polymethamethylacrylate with a melting point above 160˚C. Test samples of different material compositions and geometries were made to examine temperature-depending material properties. Two useful effects were identified: temperature-dependent change in stiffness and the shape memory effect. In certain examinations, carbonyl iron particles were also included to find out if the two particle systems are compatible with each other and can be combined in the polydimethylsiloxane matrix without disadvantages. Changes in shore hardness before and after the influence of temperature were investigated. Micro computed tomography images and scanning electron microscopy images of the respective samples were also obtained in order to detect the temperature influence on the material internally as well as on the surface of the thermosensitive elastomers in combination with carbonyl iron particles. In order to investigate the heat transfer within the samples, heating tests were carried out and the influence of different particle concentrations of the thermosensitive elastomers with and without carbonyl iron particles was determined. Further work will focus on comprehensive investigations of thermo-magneto-sensitive elastomers, as this will enable the functional integration in the material to be implemented with increased efficiency. By means of the different investigations, the authors see future applications for this class of materials in adaptive sensor and gripper elements in soft robotics.
Zeußel, Lisa; Mai, Patrick; Sharma, Sanjay; Schober, Andreas; Ren, Shizhan; Singh, Sukhdeep;
Colorimetric method for instant detection of lysine and arginine using novel Meldrum's acid-furfural conjugate. - In: ChemistrySelect, ISSN 2365-6549, Bd. 6 (2021), 27, S. 6834-6840

In the past few years Meldrum's acid furfural conjugate (MAFC) have been extensively explored as starting material for the synthesis of photo switchable donor acceptor stenhouse adducts (DASA). Hereby, we have explored the interaction of MAFC with various amino acids. To our surprise, nitrogen rich amino acids like lysine and arginine interact spontaneously with MAFC to give colored adduct immediately, whereas other amino acids, including nitrogen rich histidine, didn't show any coloration. Naked eye detection of lysine in benign solvent make this reagent an attractive new entry to the collection of chemosensors for the colorimetric detection of lysine and arginine. Intense coloration corresponds to the absorption at 514 nm under UV-Vis spectrometer. Lowest concentration of 100 m can be detected with UV-Vis spectrometer. NMR titrations reveals that the appearance of color is due to ring opening of a furfural that leads to the formation of conjugated triene species. Compared to previously reported chemosensors for lysine and arginine, MAFC offers advantages including simple synthesis, easy handling, high speed, low cost, good sensitivity/selectivity.
Ortlepp, Ingo; Fröhlich, Thomas; Füßl, Roland; Reger, Johann; Schäffel, Christoph; Sinzinger, Stefan; Strehle, Steffen; Theska, René; Zentner, Lena; Zöllner, Jens-Peter; Rangelow, Ivo W.; Reinhardt, Carsten; Hausotte, Tino; Cao, Xinrui; Dannberg, Oliver; Fern, Florian; Fischer, David; Gorges, Stephan; Hofmann, Martin; Kirchner, Johannes; Meister, Andreas; Sasiuk, Taras; Schienbein, Ralf; Supreeti, Shraddha; Mohr-Weidenfeller, Laura; Weise, Christoph; Reuter, Christoph; Stauffenberg, Jaqueline; Manske, Eberhard;
Tip- and laser-based 3D nanofabrication in extended macroscopic working areas. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 132-148

The field of optical lithography is subject to intense research and has gained enormous improvement. However, the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies. This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable: custom design and solutions for specific applications will dominate future development (Fritze in: Panning EM, Liddle JA (eds) Novel patterning technologies. International society for optics and photonics. SPIE, Bellingham, 2021. For this reason, new aspects arise for future lithography, which is why enormous effort has been directed to the development of alternative fabrication technologies. Yet, the technologies emerging from this process, which are promising for coping with the current resolution and accuracy challenges, are only demonstrated as a proof-of-concept on a lab scale of several square micrometers. Such scale is not adequate for the requirements of modern lithography; therefore, there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies. Similar challenges arise because of the technical progress in various other fields, realizing new and unique functionalities based on nanoscale effects, e.g., in nanophotonics, quantum computing, energy harvesting, and life sciences. Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks, which are available at the Technische Universität Ilmenau in the form of nanopositioning and nanomeasuring (NPM) machines. With this equipment, the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters.
Bouza, Gemayqzel; Quintana, Ernest; Tammer, Christiane;
A steepest descent method for set optimization problems with set-valued mappings of finite cardinality. - In: Journal of optimization theory and applications, ISSN 1573-2878, Bd. 190 (2021), 3, S. 711-743

In this paper, we study a first-order solution method for a particular class of set optimization problems where the solution concept is given by the set approach. We consider the case in which the set-valued objective mapping is identified by a finite number of continuously differentiable selections. The corresponding set optimization problem is then equivalent to find optimistic solutions to vector optimization problems under uncertainty with a finite uncertainty set. We develop optimality conditions for these types of problems and introduce two concepts of critical points. Furthermore, we propose a descent method and provide a convergence result to points satisfying the optimality conditions previously derived. Some numerical examples illustrating the performance of the method are also discussed. This paper is a modified and polished version of Chapter 5 in the dissertation by Quintana (On set optimization with set relations: a scalarization approach to optimality conditions and algorithms, Martin-Luther-Universität Halle-Wittenberg, 2020).
Prinke, Philipp; Haueisen, Jens; Klee, Sascha; Rizqie, Muhammad Qurhanul; Supriyanto, Eko; König, Karsten; Breunig, Hans Georg; Piatek, Lukasz;
Automatic segmentation of skin cells in multiphoton data using multi-stage merging. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 14534, insges. 19 S.

We propose a novel automatic segmentation algorithm that separates the components of human skin cells from the rest of the tissue in fluorescence data of three-dimensional scans using non-invasive multiphoton tomography. The algorithm encompasses a multi-stage merging on preprocessed superpixel images to ensure independence from a single empirical global threshold. This leads to a high robustness of the segmentation considering the depth-dependent data characteristics, which include variable contrasts and cell sizes. The subsequent classification of cell cytoplasm and nuclei are based on a cell model described by a set of four features. Two novel features, a relationship between outer cell and inner nucleus (OCIN) and a stability index, were derived. The OCIN feature describes the topology of the model, while the stability index indicates segment quality in the multi-stage merging process. These two new features, combined with the local gradient magnitude and compactness, are used for the model-based fuzzy evaluation of the cell segments. We exemplify our approach on an image stack with 200 × 200 × 100 [my]m^3, including the skin layers of the stratum spinosum and the stratum basale of a healthy volunteer. Our image processing pipeline contributes to the fully automated classification of human skin cells in multiphoton data and provides a basis for the detection of skin cancer using non-invasive optical biopsy.
Cao, Jialan; Chande, Charmi; Kalensee, Franziska; Schüler, Tim; Köhler, Michael;
Microfluidically supported characterization of responses of Rhodococcus erythropolis strains isolated from different soils on Cu-, Ni-, and Co-stress. - In: Brazilian journal of microbiology, ISSN 1678-4405, Bd. 52 (2021), 3, S. 1405-1415

We present a new methodological approach for the assessment of the susceptibility of Rhodococcus erythropolis strains from specific sampling sites in response to increasing heavy metal concentration (Cu2+, Ni2+, and Co2+) using the droplet-based microfluid technique. All isolates belong to the species R. erythropolis identified by Sanger sequencing of the 16S rRNA. The tiny step-wise variation of metal concentrations from zero to the lower mM range in 500 nL droplets not only provided accurate data for critical metal ion concentrations but also resulted in a detailed visualization of the concentration-dependent response of bacterial growth and autofluorescence activity. As a result, some of the isolates showed similar characteristics in heavy metal tolerance against Cu2+, Ni2+, and Co2+. However, significantly different heavy metal tolerances were found for other strains. Surprisingly, samples from the surface soil of ancient copper mining areas supplied mostly strains with a moderate sensitivity to Cu2+, Ni2+, and Co2+, but in contrast, a soil sample from an excavation site of a medieval city that had been covered for about eight centuries showed an extremely high tolerance against cobalt ion (up to 36 mM). The differences among the strains not only may be regarded as results of adaptation to the different environmental conditions faced by the strains in nature but also seem to be related to ancient human activities and temporal partial decoupling of soil elements from the surface. This investigation confirmed that microfluidic screening offers empirical characterization of properties from same species which has been isolated from sites known to have different human activities in the past.
Reimann, Jan; Hammer, Stefan; Henckell, Philipp; Rohe, Maximilian; Ali, Yarop; Rauch, Alexander; Hildebrand, Jörg; Bergmann, Jean Pierre;
Directed energy deposition-arc (DED-Arc) and numerical welding simulation as a hybrid data source for future machine learning applications. - In: Applied Sciences, ISSN 2076-3417, Bd. 11 (2021), 15, 7075, insges. 16 S.

This research presents a hybrid approach to generate sample data for future machine learning applications for the prediction of mechanical properties in directed energy deposition-arc (DED-Arc) using the GMAW process. DED-Arc is an additive manufacturing process which offers a cost-effective way to generate 3D metal parts, due to its high deposition rate of up to 8 kg/h. The mechanical properties additively manufactured wall structures made of the filler material G4Si1 (ER70 S-6) are shown in dependency of the t8/5 cooling time. The numerical simulation is used to link the process parameters and geometrical features to a specific t8/5 cooling time. With an input of average welding power, welding speed and geometrical features such as wall thickness, layer height and heat source size a specific temperature field can be calculated for each iteration in the simulated welding process. This novel approach allows to generate large, artificial data sets as training data for machine learning methods by combining experimental results to generate a regression equation based on the experimentally measured t8/5 cooling time. Therefore, using the regression equations in combination with numerically calculated t8/5 cooling times an accurate prediction of the mechanical properties was possible in this research with an error of only 2.6%. Thus, a small set of experimentally generated data set allows to achieve regression equations which enable a precise prediction of mechanical properties. Moreover, the validated numerical welding simulation model was suitable to achieve an accurate calculation of the t8/5 cooling time, with an error of only 0.3%.
Cheng, Yao; Riesmeyer, Michael; Haueisen, Jens; Haardt, Martin;
Using the multi-linear rank-(Lr, Lr, 1) decomposition for the detection of the 200 Hz band activity in somatosensory evoked magnetic fields and somatosensory evoked electrical potentials. - In: IEEE access, ISSN 2169-3536, Bd. 9 (2021), S. 106232-106244
Im Titel ist "r" tiefgestellt
Lauer, Kevin; Brokmann, Geert; Bähr, Mario; Ortlepp, Thomas;
Determination of piezo-resistive coefficient π44 in p-type silicon by comparing simulation and measurement of pressure sensors. - In: AIP Advances, ISSN 2158-3226, Bd. 11 (2021), 8, 085005, insges. 6 S.
Cierpka, Christian; Otto, Henning; Poll, Constanze; Hüther, Jonas; Jeschke, Sebastian; Mäder, Patrick;
SmartPIV: flow velocity estimates by smartphones for education and field studies. - In: Experiments in fluids, ISSN 1432-1114, Bd. 62 (2021), 8, 172, insges. 13 S.

In this paper, a smartphone application is presented that was developed to lower the barrier to introduce particle image velocimetry (PIV) in lab courses. The first benefit is that a PIV system using smartphones and a continuous wave (cw-) laser is much cheaper than a conventional system and thus much more affordable for universities. The second benefit is that the design of the menus follows that of modern camera apps, which are intuitively used. Thus, the system is much less complex and costly than typical systems, and our experience showed that students have much less reservations to work with the system and to try different parameters. Last but not least the app can be applied in the field. The relative uncertainty was shown to be less than 8%, which is reasonable for quick velocity estimates. An analysis of the computational time necessary for the data evaluation showed that with the current implementation the app is capable of providing smooth live display vector fields of the flow. This might further increase the use of modern measurement techniques in industry and education.
Gholamhosseinian, Ashkan; Seitz, Jochen;
Vehicle classification in intelligent transport systems: an overview, methods and software perspective. - In: IEEE open journal of intelligent transportation systems, ISSN 2687-7813, Bd. 2 (2021), S. 173-194
Kriesell, Matthias;
A note on uniquely 10-colorable graphs. - In: Journal of graph theory, ISSN 1097-0118, Bd. 98 (2021), 1, S. 24-26

Hadwiger conjectured that every graph of chromatic number k admits a clique minor of order k. Here we prove for k ≤ 10, that every graph of chromatic number k with a unique k-coloring (up to the color names) admits a clique minor of order k. The proof does not rely on the Four Color Theorem.
Pritzl, Rupert F. J.; Söllner, Fritz;
Rational climate policy - economic demands and political obstacles :
Rationale Klimapolitik - ökonomische Anforderungen und politische Hindernisse. - In: List Forum für Wirtschafts- und Finanzpolitik, ISSN 2364-3943, Bd. 46 (2021), 4, S. 423-449

In der klimapolitischen Debatte stehen meist einzelne Instrumente und Maßnahmen im Vordergrund, wohingegen die Frage der ökonomischen Rationalität der Klimapolitik als solcher häufig vernachlässigt wird. Eine Klimapolitik wäre dann ökonomisch rational, wenn politisch vorgegebene Klimaziele mit geringstmöglichen Kosten realisiert werden würden. Notwendig hierfür ist eine umfassende und einheitliche Bepreisung der Treibhausgasemissionen. Dieser rationalen Klimapolitik wird die aktuelle deutsche und europäische Politik gegenübergestellt, die sich als ineffektiv und ineffizient erweist. Ursächlich hierfür sind die Anreize, denen die politischen Akteure unterliegen und die zu einem Widerspruch zwischen ökonomischer Rationalität und politischer Opportunität führen.
Li, Feitao; Oliva Ramírez, Manuel; Wang, Dong; Schaaf, Peter;
Formation and evolution of Au-SiOx heterostructures: from nanoflowers to nanosprouts. - In: Materials and design, ISSN 1873-4197, Bd. 209 (2021), 109956, insges. 11 S.
Im Titel ist "x" tiefgestellt

This work reports the formation of circular cavities and Au-SiOx nanoflowers after annealing of thin Au film deposited on SiO2/Si substrates, and the transformation of nanoflowers to nanosprouts with increasing the annealing time. Two reference experiments indicate that both H2 and Si are indispensable for the above structures. The formation of cavities can be attributed to the SiO2 layer decomposition and the product, volatile SiO, provides a Si source for the formation of nanoflowers at the early stage. A model is proposed to indicate that SiO gas produced at the Si/SiO2 interface can diffuse to the surface assisted by the defects in the SiO2 layer before the decomposed cavities are exposed. Then the exposing of those cavities introduces another volatile SiO from the active oxidation of Si substrate, provoking a change in the direction of the main Si source, which in turn makes the one nanoparticle of the nanoflower split in two and finally form the nanosprout. The model about the escape of SiO further details SiO2 decomposition process, and the transformation mechanism from nanoflowers to nanosprout sheds light on a feasible nanofabrication method to design tunable size and shape of nanoparticles.
Visaveliya, Nikunjkumar R.; Köhler, Michael;
Softness meets with brightness: dye-doped multifunctional fluorescent polymer particles via microfluidics for labeling. - In: Advanced optical materials, ISSN 2195-1071, Bd. 9 (2021), 13, 2002219, insges. 22 S.

Fluorogenic labeling strategies have emerged as powerful tools for in vivo and in vitro imaging applications for diagnostic and theranostic purposes. Free organic chromophores (fluorescent dyes) are bright but rapidly degrade. Inorganic nanoparticles (e.g., quantum dots) are photostable but toxic to biological systems. Alternatively, dye-doped polymer particles are promising for labeling and imaging due to their properties that overcome limitations of photodegradation and toxicity. This progress report, therefore, presents various synthesis techniques for the generation of dye-doped fluorescent polymer particles. Polymer particles are relatively soft compared to inorganic nanoparticles and can be synthesized with characteristics like biocompatibility and stimuli responsiveness. Also, their ability of loading fluorophores through various interactions reveals brightness. Here, a multiscale-multicolor library of bright and soft fluorescent polymer particles is generated hierarchically. Various microfluidic supported strategies have been applied where fluorophores can be linked to polymeric networks noncovalently and covalently in the interior, and at the surface of nanoparticles (60-550 nm). Besides, microfluidic strategies for hydrophilic and hydrophobic fluorescent polymer microparticles (20-800 [my]m) have been performed for systematic tuning in size and color combination. Furthermore, soft and bright particulate assemblies are enabled through interfacial interactions at the intermediate scale (600 nm-3 [my]m) between the nanometer and micrometer lengthscale.
Mäder, Patrick; Boho, David; Rzanny, Michael Carsten; Seeland, Marco; Wittich, Hans Christian; Deggelmann, Alice; Wäldchen, Jana;
The Flora Incognita app - interactive plant species identification. - In: Methods in ecology and evolution, ISSN 2041-210X, Bd. 12 (2021), 7, S. 1335-1342

Being able to identify plant species is an important factor for understanding biodiversity and its change due to natural and anthropogenic drivers. We discuss the freely available Flora Incognita app for Android, iOS and Harmony OS devices that allows users to interactively identify plant species and capture their observations. Specifically developed deep learning algorithms, trained on an extensive repository of plant observations, classify plant images with yet unprecedented accuracy. By using this technology in a context-adaptive and interactive identification process, users are now able to reliably identify plants regardless of their botanical knowledge level. Users benefit from an intuitive interface and supplementary educational materials. The captured observations in combination with their metadata provide a rich resource for researching, monitoring and understanding plant diversity. Mobile applications such as Flora Incognita stimulate the successful interplay of citizen science, conservation and education.
Köcher, Chris;
Reachability problems on reliable and lossy queue automata. - In: Theory of computing systems, ISSN 1433-0490, Bd. 65 (2021), 8, S. 1211-1242

We study the reachability problem for queue automata and lossy queue automata. Concretely, we consider the set of queue contents which are forwards resp. backwards reachable from a given set of queue contents. Here, we prove the preservation of regularity if the queue automaton loops through some special sets of transformation sequences. This is a generalization of the results by Boigelot et al. and Abdulla et al. regarding queue automata looping through a single sequence of transformations. We also prove that our construction is possible in polynomial time.
Köhler, Michael; Beetz, Nancy; Günther, Mike; Möller, Frances; Cao, Jialan;
Extremophiles in soil communities of former copper mining sites of the East Harz region (Germany) reflected by re-analyzed 16S rRNA data. - In: Microorganisms, ISSN 2076-2607, Bd. 9 (2021), 7, 1422, insges. 16 S.

The east and southeast rim of Harz mountains (Germany) are marked by a high density of former copper mining places dating back from the late 20th century to the middle age. A set of 18 soil samples from pre- and early industrial mining places and one sample from an industrial mine dump have been selected for investigation by 16S rRNA and compared with six samples from non-mining areas. Although most of the soil samples from the old mines show pH values around 7, RNA profiling reflects many operational taxonomical units (OTUs) belonging to acidophilic genera. For some of these OTUs, similarities were found with their abundances in the comparative samples, while others show significant differences. In addition to pH-dependent bacteria, thermophilic, psychrophilic, and halophilic types were observed. Among these OTUs, several DNA sequences are related to bacteria which are reported to show the ability to metabolize special substrates. Some OTUs absent in comparative samples from limestone substrates, among them Thaumarchaeota were present in the soil group from ancient mines with pH > 7. In contrast, acidophilic types have been found in a sample from a copper slag deposit, e.g., the polymer degrading bacterium Granulicella and Acidicaldus, which is thermophilic, too. Soil samples of the group of pre-industrial mines supplied some less abundant, interesting OTUs as the polymer-degrading Povalibacter and the halophilic Lewinella and Halobacteriovorax. A particularly high number of bacteria (OTUs) which had not been detected in other samples were found at an industrial copper mine dump, among them many halophilic and psychrophilic types. In summary, the results show that soil samples from the ancient copper mining places contain soil bacterial communities that could be a promising source in the search for microorganisms with valuable metabolic capabilities.
Nozdrenko, Dmytro; Matvienko, Tetiana; Vygovska, Oksana; Bogutska, Kateryna; Motuziuk, Olexandr; Nurishchenko, Natalia; Prylutskyy, Yuriy; Scharff, Peter; Ritter, Uwe;
Protective effect of water-soluble C60 fullerene nanoparticles on the ischemia-reperfusion injury of the muscle soleus in rats. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 22 (2021), 13, 6812, insges. 13 S.
Im Titel ist "60" tiefgestellt

The biomechanical parameters of muscle soleus contraction in rats and their blood biochemical indicators after the intramuscular administration of water-soluble C60 fullerene at doses of 0.5, 1, and 2 mg/kg 1 h before the onset of muscle ischemia were investigated. In particular, changes in the contraction force of the ischemic muscle soleus, the integrated power of the muscle, the time to achieve the maximum force response, the dynamics of fatigue processes, and the parameters of the transition from dentate to smooth tetanus, levels of creatinine, creatine kinase, lactate and lactate dehydrogenase, and parameters of prooxidant-antioxidant balance (thiobarbituric acid reactive substances, hydrogen peroxide, and reduced glutathione and catalase) were analyzed. The positive therapeutic changes in the studied biomechanical and biochemical markers were revealed, which indicate the possibility of using water-soluble C60 fullerenes as effective prophylactic nanoagents to reduce the severity of pathological conditions of the muscular system caused by ischemic damage to skeletal muscles.
Weigert, Florian; Hebenstreit, Roman; Füßl, Roland; Theska, René;
Experimental setup for the investigation of reproducibility of novel tool changing systems in nanofabrication machines. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 181-189

Nanomeasuring machines developed at the Technische Universität Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest uncertainties. Due to the requirements for these processes, a highly reproducible and long-term stable tool changing system is needed. For this purpose, kinematically determined couplings are widely used. The state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application. A theoretical determination of the reproducibility based on analytical or numerical methods is possible, however not in the desired nanometer range. Due to this, a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was developed. First, potential measuring devices are systematically examined and measurement principles were developed out of this. A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further design. As a result, a translatory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be reached. Afterwards, the measurement setup is designed, focusing on the metrological frame and the lift-off device. The developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude, allowing new in-depth investigations of the reproducibility of kinematic couplings.
Straube, Guido; Fischer Calderón, Juan Sebastian; Ortlepp, Ingo; Füßl, Roland; Manske, Eberhard;
A heterodyne interferometer with separated beam paths for high-precision displacement and angular measurements. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 200-207

As standard concepts for precision positioning within a machine reach their limits with increasing measurement volumes, inverse concepts are a promising approach for addressing this problem. The inverse principle entails other limitations, as for high-precision positioning of a sensor head within a large measurement volume, three four-beam interferometers are required in order to measure all necessary translations and rotations of the sensor head and reconstruct the topography of the reference system consisting of fixed mirrors in the x-, y-, and z-directions. We present the principle of a passive heterodyne laser interferometer with consequently separated beam paths for the individual heterodyne frequencies. The beam path design is illustrated and described, as well as the design of the signal-processing and evaluation algorithm, which is implemented using a System-On-a-Chip with an integrated FPGA, CPU, and A/D converters. A streamlined bench-top optical assembly was set up and measurements were carried out to investigate the remaining non-linearities. Additionally, reference measurements with a commercial homodyne interferometer were executed.
Cao, Xinrui; Feßer, Patrick; Sinzinger, Stefan;
Lau effect using LED array for lithography. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 165-174

Illumination with LEDs is of increasing interest in imaging and lithography. In particular, compared to lasers, LEDs are temporally and spatially incoherent, so that speckle effects can be avoided by the application of LEDs. Besides, LED arrays are qualified due to their high optical output power. However, LED arrays have not been widely used for investigating optical effects, e.g., the Lau effect. In this paper, we propose the application of an LED array for realizing the Lau effect by taking into account the influence of the coherence properties of illumination on the Lau effect. Using spatially incoherent illumination with the LED array or a single LED, triangular distributed Lau fringes can be obtained. We apply the obtained Lau fringes in the optical lithography to produce analog structures. Compared to a single LED, the Lau fringes using the LED array have significantly higher intensities. Hence, the exposure time in the lithography process is largely reduced.
Ortlepp, Ingo; Zöllner, Jens-Peter; Rangelow, Ivo W.; Manske, Eberhard;
Heterodyne standing-wave interferometer with improved phase stability. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 190-199

This paper describes a standing-wave interferometer with two laser sources of different wavelengths, diametrically opposed and emitting towards each other. The resulting standing wave has an intensity profile which is moving with a constant velocity, and is directly detected inside the laser beam by two thin and transparent photo sensors. The first sensor is at a fixed position, serving as a phase reference for the second one which is moved along the optical axis, resulting in a frequency shift, proportional to the velocity. The phase difference between both sensors is evaluated for the purpose of interferometric length measurements.
Weigel, Christoph; Phi, Hai Binh; Denissel, Felix Arthur; Hoffmann, Martin; Sinzinger, Stefan; Strehle, Steffen;
Highly anisotropic fluorine-based plasma etching of ultralow expansion glass. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 23 (2021), 6, 2001336, insges. 10 S.

Deep etching of glass and glass ceramics is far more challenging than silicon etching. For thermally insensitive microelectromechanical and microoptical systems, zero-expansion materials such as Zerodur or ultralow expansion (ULE) glass are intriguing. In contrast to Zerodur that exhibits a complex glass network composition, ULE glass consists of only two components, namely, TiO2 and SiO2. This fact is highly beneficial for plasma etching. Herein, a deep fluorine-based etching process for ULE 7972 glass is shown for the first time that yields an etch rate of up to 425 nm min^-1 while still achieving vertical sidewall angles of 87˚. The process offers a selectivity of almost 20 with respect to a nickel hard mask and is overall comparable with fused silica. The chemical surface composition is additionally investigated to elucidate the etching process and the impact of the tool configuration in comparison with previously published etching results achieved in Zerodur. Therefore, deep and narrow trenches can be etched in ULE glass with high anisotropy, which supports a prospective implementation of ULE glass microstructures, for instance, in metrology and miniaturized precision applications.
Isaac, Nishchay A.; Reiprich, Johannes; Schlag, Leslie; Moreira, Pedro H. O.; Baloochi, Mostafa; Raheja, Vishal A.; Hess, Anna-Lena; Centeno, Luis F.; Ecke, Gernot; Pezoldt, Jörg; Jacobs, Heiko O.;
Three-dimensional platinum nanoparticle-based bridges for ammonia gas sensing. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 12551, insges. 9 S.

This study demonstrates the fabrication of self-aligning three-dimensional (3D) platinum bridges for ammonia gas sensing using gas-phase electrodeposition. This deposition scheme can guide charged nanoparticles to predetermined locations on a surface with sub-micrometer resolution. A shutter-free deposition is possible, preventing the use of additional steps for lift-off and improving material yield. This method uses a spark discharge-based platinum nanoparticle source in combination with sequentially biased surface electrodes and charged photoresist patterns on a glass substrate. In this way, the parallel growth of multiple sensing nodes, in this case 3D self-aligning nanoparticle-based bridges, is accomplished. An array containing 360 locally grown bridges made out of 5 nm platinum nanoparticles is fabricated. The high surface-to-volume ratio of the 3D bridge morphology enables fast response and room temperature operated sensing capabilities. The bridges are preconditioned for ˜ 24 h in nitrogen gas before being used for performance testing, ensuring drift-free sensor performance. In this study, platinum bridges are demonstrated to detect ammonia (NH3) with concentrations between 1400 and 100 ppm. The sensing mechanism, response times, cross-sensitivity, selectivity, and sensor stability are discussed. The device showed a sensor response of ˜ 4% at 100 ppm NH3 with a 70% response time of 8 min at room temperature.
Li, Qianwen; Wang, Hang; Tang, Xinfeng; Zhou, Min; Zhao, Huaping; Xu, Yang; Xiao, Wei; Lei, Yong;
Electrical conductivity adjustment for interface capacitive-like storage in sodium-ion battery. - In: Advanced functional materials, ISSN 1616-3028, Bd. 31 (2021), 24, 2101081, insges. 11 S.

Sodium-ion battery (SIB) is significant for grid-scale energy storage. However, a large radius of Na ions raises the difficulties of ion intercalation, hindering the electrochemical performance during fast charge/discharge. Conventional strategies to promote rate performance focus on the optimization of ion diffusion. Improving interface capacitive-like storage by tuning the electrical conductivity of electrodes is also expected to combine the features of the high energy density of batteries and the high power density of capacitors. Inspired by this concept, an oxide-metal sandwich 3D-ordered macroporous architecture (3DOM) stands out as a superior anode candidate for high-rate SIBs. Taking Ni-TiO2 sandwich 3DOM as a proof-of-concept, anatase TiO2 delivers a reversible capacity of 233.3 mAh g^-1 in half-cells and 210.1 mAh g^-1 in full-cells after 100 cycles at 50 mA g^-1. At the high charge/discharge rate of 5000 mA g^-1, 104.4 mAh g^-1 in half-cells and 68 mAh g^-1 in full-cells can also be obtained with satisfying stability. In-depth analysis of electrochemical kinetics evidence that the dominated interface capacitive-like storage enables ultrafast uptaking and releasing of Na-ions. This understanding between electrical conductivity and rate performance of SIBs is expected to guild future design to realize effective energy storage.
Sousa, Marcelo Nogueira de; Sant'Ana, Ricardo; Fernandes, Rigel P.; Duarte, Julio Cesar; Apolinário, José A.; Thomä, Reiner;
Improving the performance of a radio-frequency localization system in adverse outdoor applications. - In: EURASIP journal on wireless communications and networking, ISSN 1687-1499, (2021), 123, S. 1-26

In outdoor RF localization systems, particularly where line of sight can not be guaranteed or where multipath effects are severe, information about the terrain may improve the position estimate's performance. Given the difficulties in obtaining real data, a ray-tracing fingerprint is a viable option. Nevertheless, although presenting good simulation results, the performance of systems trained with simulated features only suffer degradation when employed to process real-life data. This work intends to improve the localization accuracy when using ray-tracing fingerprints and a few field data obtained from an adverse environment where a large number of measurements is not an option. We employ a machine learning (ML) algorithm to explore the multipath information. We selected algorithms random forest and gradient boosting; both considered efficient tools in the literature. In a strict simulation scenario (simulated data for training, validating, and testing), we obtained the same good results found in the literature (error around 2 m). In a real-world system (simulated data for training, real data for validating and testing), both ML algorithms resulted in a mean positioning error around 100 ,m. We have also obtained experimental results for noisy (artificially added Gaussian noise) and mismatched (with a null subset of) features. From the simulations carried out in this work, our study revealed that enhancing the ML model with a few real-world data improves localizations overall performance. From the machine ML algorithms employed herein, we also observed that, under noisy conditions, the random forest algorithm achieved a slightly better result than the gradient boosting algorithm. However, they achieved similar results in a mismatch experiment. This works practical implication is that multipath information, once rejected in old localization techniques, now represents a significant source of information whenever we have prior knowledge to train the ML algorithm.
Nissen, Volker;
The business model data facilitator in consulting :
Das Geschäftsmodell Data Facilitator im Consulting. - In: HMD, ISSN 2198-2775, Bd. 58 (2021), 3, S. 552-564

Mit der Vervielfachung des Datenvolumens und der raschen Weiterentwicklung entsprechender Analysemethoden und Werkzeuge gibt es immer mehr Unternehmen, insbesondere aus dem kleineren Mittelstand, die aufgrund mangelnder Ressourcen und Fähigkeiten nicht in der Lage sind, ihre Datenschätze zu heben und daraus gute Entscheidungen im Hinblick auf ihre Produkte, Prozesse und Geschäftsmodelle abzuleiten. Vor diesem Hintergrund wird im vorliegenden Beitrag ein Data Facilitator Geschäftsmodell für Consultingunternehmen vorgeschlagen. Um nicht im Wettbewerb zurückzufallen, lagern hierin Unternehmen Aufgaben der Datenaufbereitung, Analyse und Interpretation an ein Beratungsunternehmen aus, das sich auf solche Themen spezialisiert hat. Berater erhalten dabei Zugriff auf kritische Datenströme des Kunden, die dann auf regelmäßiger Basis fachkundig, unter Einsatz moderner Analyseinstrumente untersucht werden. Es geht darum, frühzeitig "schwache Signale" für zukünftige kritische Entwicklungen beim Kunden zu erkennen oder Ideen für geschäftliche Verbesserungen zu entwickeln. Dabei werden die Ergebnisse dem Kunden nicht kommentarlos übermittelt, sondern Auffälligkeiten von den Beratern unter Einbringung ihres Fachwissens mit den Kunden diskutiert und interpretiert. Der Kunde trifft dann gegebenenfalls Entscheidungen auf Basis der vorliegenden Datenlage. Da diese Dienstleistung fortlaufend erbracht wird, sind hierfür neue Bezahlmodelle im Consulting sinnvoll, wie z.B. eine monatliche Pauschale. Für eine erfolgreiche Umsetzung des Geschäftsmodells sind in der Praxis eine Reihe von Problemen zu bewältigen, worauf im Beitrag ebenfalls eingegangen wird.
Döring, Nicola; Holz, Christoph;
Alcohol in social media: where is the space for prevention? :
Alkohol in sozialen Medien: wo ist der Platz für Prävention?. - In: Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz, ISSN 1437-1588, Bd. 64 (2021), 6, S. 697-706
Nozdrenko, Dmytro; Abramchuk, Olga; Prylutska, Svitlana; Vygovska, Oksana; Soroca, Vasil; Bogutska, Kateryna; Khrapatyi, Sergii; Prylutskyy, Yuriy; Scharff, Peter; Ritter, Uwe;
Analysis of biomechanical parameters of muscle soleus contraction and blood biochemical parameters in rat with chronic glyphosate intoxication and therapeutic use of C60 fullerene. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 22 (2021), 9, 4977, insges. 11 S.
Im Titel ist "60" tiefgestellt
Wang, Shouzhi; Zhao, Huaping; Lv, Songyang; Jiang, Hehe; Shao, Yongliang; Wu, Yongzhong; Hao, Xiaopeng; Lei, Yong;
Insight into nickel-cobalt oxysulfide nanowires as advanced anode for sodium-ion capacitors. - In: Advanced energy materials, ISSN 1614-6840, Bd. 11 (2021), 18, 2100408, insges. 9 S.

Transition metal oxides have a great potential in sodium-ion capacitors (SICs) due to their pronouncedly higher capacity and low cost. However, their poor conductivity and fragile structure hinder their development. Herein, core-shell-like nickel-cobalt oxysulfide (NCOS) nanowires are synthesized and demonstrated as an advanced SICs anode. The bimetallic oxysulfide with multiple cation valence can promote the sodium ion adsorption and redox reaction, massive defects enable accommodation of the volume change in the sodiation/desodiation process, meanwhile the core-shell-like structure provides abundant channels for fast transfer of sodium ions, thereby synergistically making the NCOS electrode exhibit a high reversible sodium ion storage capacity (1468.5 mAh g^-1 at 0.1 A g^-1) and an excellent cyclability (90.5% capacity retention after 1000 cycles). The in-situ X-ray diffraction analysis unravels the insertion and conversion mechanism for sodium storage in NCOS, and the enhanced capability of NCOS is further verified by the kinetic analysis and theoretical calculations. Finally, SICs consisting of the NCOS anode and a boron-nitrogen co-doped carbon nanotubes cathode deliver an energy density of 205.7 Wh kg^-1, a power density of 22.5 kW kg^-1, and an outstanding cycling lifespan. These results indicate an efficient strategy in designing a high-performance anode for sodium storage based on bimetallic dianion compounds.
Wang, Anni; Gallino, Isabella; Riegler, Sascha Sebastian; Lin, Yi-Ting; Isaac, Nishchay A.; Sauni Camposano, Yesenia Haydee; Matthes, Sebastian; Flock, Dominik; Jacobs, Heiko O.; Yen, Hung-Wei; Schaaf, Peter;
Ultrafast formation of single phase B2 AlCoCrFeNi high entropy alloy films by reactive Ni/Al multilayers as heat source. - In: Materials and design, ISSN 1873-4197, Bd. 206 (2021), 109790, insges. 12 S.

High entropy alloy films of AlCoCrFeNi B2-ordered structure are formed during an ultrafast heating process by reactive Ni/Al multilayers. The self-propagating high-temperature reaction occurring in reactive Ni/Al multilayers after ignition represents an ultrafast heat source which is used for the transformation of a thin films Al/CoFe/CrNi multilayer structure into a single-phase high entropy alloy film. The materials design of the combined multilayers thus determines the phase formation. Conventional rapid thermal annealing transforms the multilayer into a film with multiple equilibrium phases. Ultrafast combustion synthesis produces films with ultrafine-grained single-phase B2-ordered compound alloy. The heating rates during the combustion synthesis are in the order of one million K/s, much higher than those of the rapid thermal annealing, which is about 7 K/s. The results are compared with differential scanning calorimetry experiments with heating rates ranging from about 100 K/s up to 25000 K/s. It is shown that the heating rate clearly determines the phase formation in the multilayers. The rapid kinetics of the combustion prevents long-range diffusion and promotes the run-away transformation. Thus, multilayer combustion synthesis using reactive Ni/Al multilayers as heat source represents a new pathway for the fabrication of single phase high-entropy alloy films.
Mohr-Weidenfeller, Laura; Häcker, Annika-Verena; Reinhardt, Carsten; Manske, Eberhard;
Two-photon direct laser writing beyond the diffraction limit using the nanopositioning and nanomeasuring machine. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 149-155

Since the first realization of two-photon direct laser writing (DLW) in Maruo et al. (Opt Lett 22:132-134, 1997), the manufacturing using direct laser writing techniques spread out in many laboratories all over the world. Photosensitive materials with different material properties open a new field for micro- and nanofabrication. The achievable structuring resolution using this technique is reported to be sub-100 nm (Paz et al. in J. Laser Appl. 24:042004, 2012), while a smallest linewidth of 25 nm could be shown in Tan et al. (Appl Phys Lett 90:071106, 2007). In our approach, the combination of DLW with the nanopositioning and nanomeasuring machine NMM-1 offers an improvement of the technique from the engineering side regarding the ultra-precise positioning (Weidenfeller et al. in Adv Fabr Technol Micro/Nano Opt Photon XI 10544:105440E, 2018). One big benefit besides the high positioning resolution of 0.1 nm is offered by the positioning range of 25 mm × 25 mm × 5 mm (Jäger et al. in Technisches Messen 67:319-323, 2000; Manske et al. in Meas Sci Technol 18:520-527, 2007). Thus, a trans-scale fabrication without any stitching or combination of different positioning systems is necessary. The immense synergy between the highly precise positioning and the DLW is demonstrated by the realization of resist lines and trenches whose center-to-center distance undergoes the modified diffraction limit for two-photon processes. The precise positioning accuracy enables a defined distance between illuminated lines. Hence, with a comparable huge width of the trenches of 1.655 [my]m due to a low effective numerical aperture of 0.16, a resist line of 30 nm between two written trenches could be achieved. Although the interrelationships for achieving such narrow trenches have not yet been clarified, much smaller resist lines and trench widths are possible with this approach in the near future.
Prokhorova, Alexandra; Ley, Sebastian; Helbig, Marko;
Quantitative interpretation of UWB radar images for non-invasive tissue temperature estimation during hyperthermia. - In: Diagnostics, ISSN 2075-4418, Bd. 11 (2021), 5, 818, insges. 16 S.

The knowledge of temperature distribution inside the tissue to be treated is essential for patient safety, workflow and clinical outcomes of thermal therapies. Microwave imaging represents a promising approach for non-invasive tissue temperature monitoring during hyperthermia treatment. In the present paper, a methodology for quantitative non-invasive tissue temperature estimation based on ultra-wideband (UWB) radar imaging in the microwave frequency range is described. The capabilities of the proposed method are demonstrated by experiments with liquid phantoms and three-dimensional (3D) Delay-and-Sum beamforming algorithms. The results of our investigation show that the methodology can be applied for detection and estimation of the temperature induced dielectric properties change.
Gizatullin, Bulat; Papmahl, Eric; Mattea, Carlos; Stapf, Siegfried;
Quantifying crude oil contamination in sand and soil by EPR spectroscopy. - In: Applied magnetic resonance, ISSN 1613-7507, Bd. 52 (2021), 5, S. 633-648

Crude oil frequently contains stable radicals that allow detection by means of EPR spectroscopy. On the other hand, most sands and soils possess significant amounts of iron, manganese or other metallic species that often provide excessively broad EPR signatures combined with well-defined sharp features by quartz defects. In this study, we demonstrate the feasibility to identify oil contamination in natural environments that are subject to oil spillage during production on land, as well as beachside accumulation of marine oil spillage. Straightforward identification of oil is enabled by the radical contributions of asphaltenes, in particular by vanadyl multiplets that are absent from natural soils. This potentially allows for high-throughput soil analysis or the application of mobile EPR scanners.
Wüster, Julian; Bourgin, Yannick; Feßer, Patrick; Behrens, Arne; Sinzinger, Stefan;
Nano-imprinted subwavelength gratings as polarizing beamsplitters. - In: Journal of the European Optical Society, ISSN 1990-2573, Bd. 17 (2021), 4, insges. 13 S.

Polarizing beamsplitters have numerous applications in optical systems, such as systems for freeform surface metrology. They are classically manufactured from birefringent materials or with stacks of dielectric coatings. We present a binary subwavelength-structured form-birefringent diffraction grating, which acts as a polarizing beamsplitter for a wide range of incidence angles -30˚ +30˚. We refine the general design method for such hybrid gratings. We furthermore demonstrate the manufacturing steps with Soft-UV-Nanoimprint-Lithography, as well as the experimental verification, that the structure reliably acts as a polarizing beamsplitter. The experimental results show a contrast in efficiency for TE- and TM-polarization of up to 1:18 in the first order, and 34:1 in the zeroth order. The grating potentially enables us to realize integrated compact optical measurement systems, such as common-path interferometers.
Schienbein, Ralf; Fern, Florian; Theska, René; Supreeti, Shraddha; Füßl, Roland; Manske, Eberhard;
Fundamental investigations in the design of five-axis nanopositioning machines for measurement and fabrication purposes. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 156-164

The majority of nanopositioning and nanomeasuring machines (NPMMs) are based on three independent linear movements in a Cartesian coordinate system. This in combination with the specific nature of sensors and tools limits the addressable part geometries. An enhancement of an NPMM is introduced by the implementation of rotational movements while keeping the precision in the nanometer range. For this purpose, a parameter-based dynamic evaluation system with quantifiable technological parameters has been set up and employed to identify and assess general solution concepts and adequate substructures. Evaluations taken show high potential for three linear movements of the object in combination with two angular movements of the tool. The influence of the additional rotation systems on the existing structure of NPMMs has been investigated further on. Test series on the repeatability of an NPMM enhanced by a chosen combination of a rotary stage and a goniometer setup are realized. As a result of these test series, the necessity of in situ position determination of the tool became very clear. The tool position is measured in situ in relation to a hemispherical reference mirror by three Fabry-Pérot interferometers. FEA optimization has been used to enhance the overall system structure with regard to reproducibility and long-term stability. Results have been experimentally investigated by use of a retroreflector as a tool and the various laser interferometers of the NPMM. The knowledge gained has been formed into general rules for the verification and optimization of design solutions for multiaxial nanopositioning machines.
Kurniawan, Mario; Stich, Michael; Marimon, Mayra; Camargo, Magali K.; Peipmann, Ralf; Hannappel, Thomas; Bund, Andreas;
Electrodeposition of cuprous oxide on a porous copper framework for an improved photoelectrochemical performance. - In: Journal of materials science, ISSN 1573-4803, Bd. 56 (2021), 20, S. 11866-11880
Leben, Leslie; Martínez Pería, Francisco; Philipp, Friedrich; Trunk, Carsten; Winkler, Henrik;
Finite rank perturbations of linear relations and matrix pencils. - In: Complex analysis and operator theory, ISSN 1661-8262, Bd. 15 (2021), 2, 37, insges. 37 S.

We elaborate on the deviation of the Jordan structures of two linear relations that are finite-dimensional perturbations of each other. We compare their number of Jordan chains of length at least n. In the operator case, it was recently proved that the difference of these numbers is independent of n and is at most the defect between the operators. One of the main results of this paper shows that in the case of linear relations this number has to be multiplied by n+1 and that this bound is sharp. The reason for this behavior is the existence of singular chains. We apply our results to one-dimensional perturbations of singular and regular matrix pencils. This is done by representing matrix pencils via linear relations. This technique allows for both proving known results for regular pencils as well as new results for singular ones.
Hesse, David; Hamatschek, Christopher; Augsburg, Klaus; Weigelt, Thomas; Prahst, Alexander; Gramstat, Sebastian;
Testing of alternative disc brakes and friction materials regarding brake wear particle emissions and temperature behavior. - In: Atmosphere, ISSN 2073-4433, Bd. 12 (2021), 4, 436$23

In this study, different disc brakes and friction materials are evaluated with respect to particle emission output and characteristic features are derived. The measurements take place on an inertia dynamometer using a constant volume sampling system. Brake wear particle emission factors of different disc concepts in different sizes are determined and compared, using a grey cast iron disc, a tungsten carbide-coated disc and a carbon ceramic disc. The brakes were tested over a section (trip #10) novel test cycle developed from the database of the worldwide harmonized Light-Duty vehicles Test Procedure (WLTP). First, brake emission factors were determined along the bedding process using a series of trip-10 tests. The tests were performed starting from unconditioned pads, to characterize the evolution of emissions until their stabilization. In addition to number- and mass-related emission factors (PM2.5-PM10), the particle size distribution was determined. Another focus was the evaluation of temperature ranges and the associated challenges in the use of temperature readings in a potential regulation of brake wear particle emissions. The results illustrate the challenges associated with establishing a universal bedding procedure and using disc temperature measurements for the control of a representative braking procedure. Using tungsten carbide coated discs and carbon ceramic discs, emission reduction potentials of up to 70% (PM10) could be demonstrated along the WLTP brake cycle. The reduction potential is primarily the result of the high wear resistance of the disc, but is additionally influenced by the pad composition and the temperature in the friction contact area.
Heydrich, Marius; Ricciardi, Vincenzo; Ivanov, Valentin; Mazzoni, Matteo; Rossi, Alessandro; Buh, Jože; Augsburg, Klaus;
Integrated braking control for electric vehicles with in-wheel propulsion and fully decoupled brake-by-wire system. - In: Vehicles, ISSN 2624-8921, Bd. 3 (2021), 2, S. 145-161
Visaveliya, Nikunjkumar R.; Köhler, Michael;
Hierarchical assemblies of polymer particles through tailored interfaces and controllable interfacial interactions. - In: Advanced functional materials, ISSN 1616-3028, Bd. 31 (2021), 9, 2007407, insges. 22 S.

Hierarchical assembly architectures of functional polymer particles are promising because of their physicochemical and surface properties for multi-labeling and sensing to catalysis and biomedical applications. While polymer nanoparticles' interior is mainly made up of the cross-linked network, their surface can be tailored with soft, flexible, and responsive molecules and macromolecules as potential support for the controlled particulate assemblies. Molecular surfactants and polyelectrolytes as interfacial agents improve the stability of the nanoparticles whereas swellable and soft shell-like cross-linked polymeric layer at the interface can significantly enhance the uptake of guest nano-constituents during assemblies. Besides, layer-by-layer surface-functionalization holds the ability to provide a high variability in assembly architectures of different interfacial properties. Considering these aspects, various assembly architectures of polymer nanoparticles of tunable size, shapes, morphology, and tailored interfaces together with controllable interfacial interactions are constructed here. The microfluidic-mediated platform has been used for the synthesis of constituents polymer nanoparticles of various structural and interfacial properties, and their assemblies are conducted in batch or flow conditions. The assemblies presented in this progress report is divided into three main categories: cross-linked polymeric network's fusion-based self-assembly, electrostatic-driven assemblies, and assembly formed by encapsulating smaller nanoparticles into larger microparticles.
Göring, Steve; Ramachandra Rao, Rakesh Rao; Feiten, Bernhard; Raake, Alexander;
Modular framework and instances of pixel-based video quality models for UHD-1/4K. - In: IEEE access, ISSN 2169-3536, Bd. 9 (2021), S. 31842-31864
Baidiuk, Dmytro; Derkach, Volodymyr; Hassi, Seppo;
Unitary boundary pairs for isometric operators in Pontryagin spaces and generalized coresolvents. - In: Complex analysis and operator theory, ISSN 1661-8262, Bd. 15 (2021), 2, 32, insges. 52 S.
Boeck, Thomas; Sanjari, Seyed Loghman; Becker, Tatiana;
Dynamics of a magnetic pendulum in the presence of an oscillating conducting plate. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 20 (2021), 1, e202000083, insges. 2 S.

A pendulum with an attached permanent magnet moving near a conductor is a typical experiment for the demonstration of electromagnetic braking. When the conductor itself moves, it can transfer energy to the pendulum. We study a simple but exact analytical model where the conductor is a horizontally unbounded flat plate. For this geometry, eddy currents and induced Lorentz force due to the motion of a magnetic dipole are known analytically in the quasistatic limit. A vertical oscillation of such a horizontal plate located beneath the magnet is considered. In this setup, the vertical position of the pendulum is an equilibrium point when the magnetic moment of the magnet is perpendicular to its plane of motion. Depending on the strength of the magnetic dipole moment, the frequency and amplitude of the plate as well as the distance between plate and magnet, the plate oscillation can destabilize the equilibrium. The stability limits for weak electromagnetic coupling are computed analytically using the harmonic balancing method. For stronger coupling, the stability limits are obtained numerically using Floquet analysis. Chaotic motions with finite amplitudes are also found.
Blum, Maren-Christina; Solf, Benjamin; Hunold, Alexander; Klee, Sascha;
Effects of ocular direct current stimulation on full field electroretinogram. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 15 (2021), 606557, S. 1-9
Seeland, Marco; Mäder, Patrick;
Multi-view classification with convolutional neural networks. - In: PLOS ONE, ISSN 1932-6203, Bd. 16 (2021), 1, e0245230, insges. 17 S.
Eichfelder, Gabriele; Warnow, Leo;
Proximity measures based on KKT points for constrained multi-objective optimization. - In: Journal of global optimization, ISSN 1573-2916, Bd. 80 (2021), 1, S. 63-86

An important aspect of optimization algorithms, for instance evolutionary algorithms, are termination criteria that measure the proximity of the found solution to the optimal solution set. A frequently used approach is the numerical verification of necessary optimality conditions such as the Karush-Kuhn-Tucker (KKT) conditions. In this paper, we present a proximity measure which characterizes the violation of the KKT conditions. It can be computed easily and is continuous in every efficient solution. Hence, it can be used as an indicator for the proximity of a certain point to the set of efficient (Edgeworth-Pareto-minimal) solutions and is well suited for algorithmic use due to its continuity properties. This is especially useful within evolutionary algorithms for candidate selection and termination, which we also illustrate numerically for some test problems.
Köhler, Tobias; Grätzel, Michael; Bergmann, Jean Pierre;
Influence of different Ni coatings on the long-term behavior of ultrasonic welded EN AW 1370 cable/EN CW 004A arrestor dissimilar joints. - In: Welding in the world, ISSN 1878-6669, Bd. 65 (2021), 3, S. 429-440

The increasing demand for energy-efficient vehicles requires suitable methods for cost and weight reduction. This can be achieved by the replacement of copper by aluminum, in particular for the on-board power systems. However, the complete substitution is restricted by the mechanical and physical material properties of aluminum as well as challenges in the aluminum copper interface. The challenges concern the corrosion vulnerability and the occurrence of brittle intermetallic compounds (IMC) which can negatively influence the mechanical properties and the electrical conductivity. Therefore, current investigations focus on the one hand on the realization of dissimilar aluminum copper joints by suitable joining technologies, like ultrasonic welding, and on the other hand on the assurance of a sufficient prevention against harmful corrosion effects. In cases where the joint cannot be protected against corrosion by sealing, nickel coatings can be used to protect the joint. In the present study, the influence of electroless, electroplated, and sulfamate nickel coatings was investigated regarding the long-term stability. The joints were performed as industry-related arrester connections, consisting of EN AW 1370 cables and EN CW 004A terminals. The samples were exposed to corrosive as well as electrical, thermal, and mechanical stress tests according to current standards and regulations.
Eichfelder, Gabriele; Klamroth, Kathrin; Niebling, Julia;
Nonconvex constrained optimization by a filtering branch and bound. - In: Journal of global optimization, ISSN 1573-2916, Bd. 80 (2021), 1, S. 31-61

A major difficulty in optimization with nonconvex constraints is to find feasible solutions. As simple examples show, the [alpha]BB-algorithm for single-objective optimization may fail to compute feasible solutions even though this algorithm is a popular method in global optimization. In this work, we introduce a filtering approach motivated by a multiobjective reformulation of the constrained optimization problem. Moreover, the multiobjective reformulation enables to identify the trade-off between constraint satisfaction and objective value which is also reflected in the quality guarantee. Numerical tests validate that we indeed can find feasible and often optimal solutions where the classical single-objective [alpha]BB method fails, i.e., it terminates without ever finding a feasible solution.
Prinz, Sebastian; Thomann, Jana; Eichfelder, Gabriele; Boeck, Thomas; Schumacher, Jörg;
Expensive multi-objective optimization of electromagnetic mixing in a liquid metal. - In: Optimization and engineering, ISSN 1573-2924, Bd. 22 (2021), 2, S. 1065-1089

This paper presents a novel trust-region method for the optimization of multiple expensive functions. We apply this method to a biobjective optimization problem in fluid mechanics, the optimal mixing of particles in a flow in a closed container. The three-dimensional time-dependent flows are driven by Lorentz forces that are generated by an oscillating permanent magnet located underneath the rectangular vessel. The rectangular magnet provides a spatially non-uniform magnetic field that is known analytically. The magnet oscillation creates a steady mean flow (steady streaming) similar to those observed from oscillating rigid bodies. In the optimization problem, randomly distributed mass-less particles are advected by the flow to achieve a homogeneous distribution (objective function 1) while keeping the work done to move the permanent magnet minimal (objective function 2). A single evaluation of these two objective functions may take more than two hours. For that reason, to save computational time, the proposed method uses interpolation models on trust-regions for finding descent directions. We show that, even for our significantly simplified model problem, the mixing patterns vary significantly with the control parameters, which justifies the use of improved optimization techniques and their further development.
Schorr, Philipp; Li, Enrique Roberto Carrillo; Kaufhold, Tobias; Hernández, Jorge Antonio Rodríguez; Zentner, Lena; Zimmermann, Klaus; Böhm, Valter;
Kinematic analysis of a rolling tensegrity structure with spatially curved members. - In: Meccanica, ISSN 1572-9648, Bd. 56 (2021), 4, S. 953-961

In this work, a tensegrity structure with spatially curved members is applied as rolling locomotion system. The actuation of the structure allows a variation of the originally cylindrical shape to a conical shape. Moreover, the structure is equipped with internal movable masses to control the position of the center of mass of the structure. To control the locomotion system a reliable actuation strategy is required. Therefore, the kinematics of the system considering the nonholonomic constraints are derived in this paper. Based on the resulting insight in the locomotion behavior a feasible actuation strategy is designed to control the trajectory of the system. To verify this approach kinematic analyses are evaluated numerically. The simulation data confirm the path following due to an appropriate shape change of the tensegrity structure. Thus, this system enables a two-dimensional rolling locomotion.
Söllner, Fritz;
[Rezension von: Rindermann, Heiner, 1966-, Cognitive capitalism]. - In: Public choice. - Dordrecht [u.a.] : Springer Science + Business Media B.V., 1966- , ISSN: 1573-7101 , ZDB-ID: 1475723-0, ISSN 1573-7101, Bd. 187 (2021), 3/4, S. 527-531
Xu, Rui; Du, Lei; Adekoya, David; Zhang, Gaixia; Zhang, Shanqing; Sun, Shuhui; Lei, Yong;
Well-defined nanostructures for electrochemical energy conversion and storage. - In: Advanced energy materials, ISSN 1614-6840, Bd. 11 (2021), 15, 2001537, insges. 53 S.

Electrochemical energy conversion and storage play crucial roles in meeting the increasing demand for renewable, portable, and affordable power supplies for society. The rapid development of nanostructured materials provides an alternative route by virtue of their unique and promising effects emerging at nanoscale. In addition to finding advanced materials, structure design and engineering of electrodes improves the electrochemical performance and the resultant commercial competitivity. Regarding the structural engineering, controlling the geometrical parameters (i.e., size, shape, hetero-architecture, and spatial arrangement) of nanostructures and thus forming well-defined nanostructure (WDN) electrodes have been the central aspects of investigations and practical applications. This review discusses the fundamental aspects and concept of WDNs for energy conversion and storage, with a strong emphasis on illuminating the relationship between the structural characteristics and the resultant electrochemical superiorities. Key strategies for actualizing well-defined features in nanostructures are summarized. Electrocatalysis and photoelectrocatalysis (for energy conversion) as well as metal-ion batteries and supercapacitors (for energy storage) are selected to illustrate the superiorities of WDNs in electrochemical reactions and charge carrier transportation. Finally, conclusions and perspectives regarding future research, development, and applications of WDNs are discussed.
Schweser, Thomas; Stiebitz, Michael;
Partitions of hypergraphs under variable degeneracy constraints. - In: Journal of graph theory, ISSN 1097-0118, Bd. 96 (2021), 1, S. 7-33
Song, Xinya; Cai, Hui; Jiang, Teng; Sennewald, Tom; Kircheis, Jan; Schlegel, Steffen; Noris Martinez, Leonel; Benzetta, Youcef; Westermann, Dirk;
Research on performance of real-time simulation based on inverter-dominated power grid. - In: IEEE access, ISSN 2169-3536, Bd. 9 (2021), S. 1137-1153
Hunold, Alexander; Machts, René; Haueisen, Jens;
Head phantoms for bioelectromagnetic applications: a material study. - In: Biomedical engineering online, ISSN 1475-925X, Bd. 19 (2020), 87, S. 1-14

Assessments of source reconstruction procedures in electroencephalography and computations of transcranial electrical stimulation profiles require verification and validation with the help of ground truth configurations as implemented by physical head phantoms. For these phantoms, synthetic materials are needed, which are mechanically and electrochemically stable and possess conductivity values similar to the modeled human head tissues. Three-compartment head models comprise a scalp layer with a conductivity range of 0.137 S/m to 2.1 S/m, a skull layer with conductivity values between 0.066 S/m and 0.00275 S/m, and an intracranial volume with an often-used average conductivity value of 0.33 S/m. To establish a realistically shaped physical head phantom with a well-defined volume conduction configuration, we here characterize the electrical conductivity of synthetic materials for modeling head compartments. We analyzed agarose hydrogel, gypsum, and sodium chloride (NaCl) solution as surrogate materials for scalp, skull, and intracranial volume. We measured the impedance of all materials when immersed in NaCl solution using a four-electrode setup. The measured impedance values were used to calculate the electrical conductivity values of each material. Further, the conductivities in the longitudinal and transverse directions of reed sticks immersed in NaCl solution were measured to test their suitability for mimicking the anisotropic conductivity of white matter tracts.
Budzinski, Oliver; Gänßle, Sophia; Stöhr, Annika;
The proposal of a 10th amendment of German competition law: interventionism or laissez-faire? :
Der Entwurf zur 10. GWB Novelle: Interventionismus oder Laissez-faire?. - In: List Forum für Wirtschafts- und Finanzpolitik, ISSN 2364-3943, Bd. 46 (2020), 2, S. 157-184
Rochyadi-Reetz, Mira; Budiono, Olivia Deskarina; Wolling, Jens;
Regularity of a crisis: media framing of the 2015 transboundary haze issue in Indonesia, Singapore, and Malaysia. - In: Jurnal Komunikasi, ISSN 0128-1496, Bd. 36 (2020), 2, S. 415-433
Richtiger Name des Verfassers: Olivia Deskarina Budiono

The problem of the haze caused by huge forest fires persists as an annual transboundary problem for Indonesia and the rest of Southeast Asia. In 2015, the problem was worse than ever before, affecting many countries in the Association of Southeast Asian Nations (ASEAN) and causing respiratory ailments for more than half a million Indonesians. This study explores the media framing of the haze problem in Indonesia from June to December 2015. Using Entmans framing approach, it investigates how media outlets from Indonesia, Malaysia, and Singapore covered the crisis. Articles from six online media outlets published in these three countries were analysed. Using cluster analysis, this research identified three frames as follows: (1) crisis frame, (2) immediate action frame, and (3) regular problem frame. The first cluster/frame consists of articles giving high salience to all problems and causes of the forest fires provoking the haze. In contrast, the second frame mostly ignores causes and problems and focuses almost exclusively on the need for immediate action. The third frame, which represents more than 60% of the articles, covers the haze problem as a regular issue without emphasizing prominently either the different aspects of the problem itself or its causes and solutions. Further results show that the media in Singapore and Malaysia used the crisis frame more often than the media in Indonesia.
Boeck, Thomas; Sanjari, Seyed Loghman; Becker, Tatiana;
Parametric instability of a magnetic pendulum in the presence of a vibrating conducting plate. - In: Nonlinear dynamics, ISSN 1573-269X, Bd. 102 (2020), 4, S. 2039-2056

A pendulum with an attached permanent magnet swinging in the vicinity of a conductor is a typical experiment for the demonstration of electromagnetic braking and Lenz law of induction. When the conductor itself moves, it can transfer energy to the pendulum. An exact analytical model of such an electromagnetic interaction is possible for a flat conducting plate. The eddy currents induced in the plate by a moving magnetic dipole and the resulting force and torque are known analytically in the quasistatic limit, i.e., when the magnetic diffusivity is sufficiently high to ensure an equilibrium of magnetic field advection and diffusion. This allows us to study a simple pendulum with a magnetic dipole moment in the presence of a horizontal plate oscillating in vertical direction. Equilibrium of the pendulum in the vertical position can be realized in three cases considered, i.e., when the magnetic moment is parallel to the rotation axis, or otherwise, its projection onto the plane of motion is either horizontal or vertical. The stability problem is described by a differential equation of Mathieu type with a damping term. Instability is only possible when the vibration amplitude and the distance between plate and magnet satisfy certain constraints related to the simultaneous excitation and damping effects of the plate. The nonlinear motion is studied numerically for the case when the magnetic moment and rotation axis are parallel. Chaotic behavior is found when the eigenfrequency is sufficiently small compared to the excitation frequency. The plate oscillation typically has a stabilizing effect on the inverted pendulum.
Angermeier, Sebastian; Karcher, Christian;
Model-based condenser fan speed optimization of vapor compression systems. - In: Energies, ISSN 1996-1073, Volume 13 (2020), issue 22, 6012, Seite 1-26

Vapor compression systems (VCS) cover a wide range of applications and consume large amounts of energy. In this context, previous research identified the optimization of the condenser fans speed as a promising measure to improve the energy efficiency of VCS. The present paper introduces a steady-state modeling approach of an air-cooled VCS to predict the ideal condenser fan speed. The model consists of a hybrid characterization of the main components of a VCS and the optimization problem is formulated as minimizing the total energy consumption by respectively adjusting the condenser fan and compressor speed. In contrast to optimization strategies found in the literature, the proposed model does not relay on algorithms, but provides a single optimization term to predict the ideal fan speed. A detailed experimental validation demonstrates the feasibility of the model approach and further suggests that the ideal condenser fan speed can be calculated with sufficient precision, assuming constant evaporating pressure, compressor efficiency, subcooling, and superheating, respectively. In addition, a control strategy based on the developed model is presented, which is able to drive the VCS to its optimal operation. Therefore, the study provides a crucial input for set-point optimization and steady-state modeling of air-cooled vapor compression systems.
Chehreh, Abootorab; Grätzel, Michael; Bergmann, Jean Pierre; Walther, Frank;
Fatigue behavior of conventional and stationary shoulder friction stir welded EN AW-5754 aluminum alloy using load increase method. - In: Metals, ISSN 2075-4701, Bd. 10 (2020), 11, 1510, insges. 11 S.
Zhang, Chen; Gebhart, Ingo; Kühmstedt, Peter; Rosenberger, Maik; Notni, Gunther;
Enhanced contactless vital sign estimation from real-time multimodal 3D image data. - In: Journal of imaging, ISSN 2313-433X, Volume 6 (2020), issue 11, 123, Seite 1-15
Glombiewski, Nikolaus; Götze, Philipp; Körber, Michael; Morgen, Andreas; Seeger, Bernhard;
Designing an event store for a modern three-layer storage hierarchy. - In: Datenbank-Spektrum, ISSN 1610-1995, Bd. 20 (2020), 3, S. 211-222

Event stores face the difficult challenge of continuously ingesting massive temporal data streams while satisfying demanding query and recovery requirements. Many of todays systems deal with multiple hardware-based trade-offs. For instance, long-term storage solutions balance keeping data in cheap secondary media (SSDs, HDDs) and performance-oriented main-memory caches. As an alternative, in-memory systems focus on performance, while sacrificing monetary costs, and, to some degree, recovery guarantees. The advent of persistent memory (PMem) led to a multitude of novel research proposals aiming to alleviate those trade-offs in various fields. So far, however, there is no proposal for a PMem-powered specialized event store.
Xu, Rui; Wen, Liaoyong; Wang, Zhijie; Zhao, Huaping; Mu, Guannan; Zeng, Zhiqiang; Zhou, Min; Bohm, Sebastian; Zhang, Huanming; Wu, Yuhan; Runge, Erich; Lei, Yong;
Programmable multiple plasmonic resonances of nanoparticle superlattice for enhancing photoelectrochemical activity. - In: Advanced functional materials, ISSN 1616-3028, Bd. 30 (2020), 48, 2005170, insges. 10 S.
Schricker, Klaus; Alhomsi, Mohammad; Bergmann, Jean Pierre;
Thermal efficiency in laser-assisted joining of polymer-metal composites. - In: Materials, ISSN 1996-1944, Bd. 13 (2020), 21, 4875, insges. 16 S.
Raake, Alexander; Borer, Silvio; Satti, Shahid M.; Gustafsson, Jörgen; Ramachandra Rao, Rakesh Rao; Medagli, Stefano; List, Peter; Göring, Steve; Lindero, David; Robitza, Werner; Heikkilä, Gunnar; Broom, Simon; Schmidmer, Christian; Feiten, Bernhard; Wüstenhagen, Ulf; Wittmann, Thomas; Obermann, Matthias; Bitto, Roland;
Multi-model standard for bitstream-, pixel-based and hybrid video quality assessment of UHD/4K: ITU-T P.1204. - In: IEEE access, ISSN 2169-3536, Bd. 8 (2020), S. 193020-193049
Zhang, Qingcheng; Zhao, Junping; Wu, Yechao; Li, Jun; Jin, Huile; Zhao, Shiqiang; Chai, Lulu; Wang, Yahui; Lei, Yong; Wang, Shun;
Rapid and controllable synthesis of nanocrystallized nickel-cobalt boride electrode materials via a mircoimpinging stream reaction for high performance supercapacitors. - In: Small, ISSN 1613-6829, Bd. 16 (2020), 39, 2003342, insges. 13 S.

Nickel-cobalt borides (denoted as NCBs) have been considered as a promising candidate for aqueous supercapacitors due to their high capacitive performances. However, most reported NCBs are amorphous that results in slow electron transfer and even structure collapse during cycling. In this work, a nanocrystallized NCBs-based supercapacitor is successfully designed via a facile and practical microimpinging stream reactor (MISR) technique, composed of a nanocrystallized NCB core to facilitate the charge transfer, and a tightly contacted Ni-Co borates/metaborates (NCBi) shell which is helpful for OH^- adsorption. These merits endow NCBNCBi a large specific capacity of 966 C g^-1 (capacitance of 2415 F g^-1) at 1 A g^-1 and good rate capability (633.2 C g^-1 at 30 A g^-1), as well as a very high energy density of 74.3 Wh kg^-1 in an asymmetric supercapacitor device. More interestingly, it is found that a gradual in situ conversion of core NCBs to nanocrystallized Ni-Co (oxy)-hydroxides inwardly takes place during the cycles, which continuously offers large specific capacity due to more electron transfer in the redox reaction processes. Meanwhile, the electron deficient state of boron in metal-borates shells can make it easier to accept electrons and thus promote ionic conduction.
Angermeier, Sebastian; Ketterer, Jonas; Karcher, Christian;
Liquid-based battery temperature control of electric buses. - In: Energies, ISSN 1996-1073, Volume 13 (2020), issue 19, 4990, Seite 1-20

Previous research identified that battery temperature control is critical to the safety, lifetime, and performance of electric vehicles. In this paper, the liquid-based battery temperature control of electric buses is investigated subject to heat transfer behavior and control strategy. Therefore, a new transient calculation method is proposed to simulate the thermal behavior of a coolant-cooled battery system. The method is based on the system identification technique and combines the advantage of low computational effort and high accuracy. In detail, four transfer functions are extracted by a thermo-hydraulic 3D simulation model comprising 12 prismatic lithium nickel manganese cobalt oxide (NMC) cells, housing, arrestors, and a cooling plate. The transfer functions describe the relationship between heat generation, cell temperature, and coolant temperature. A vehicle model calculates the power consumption of an electric bus and thus provides the input for the transient calculation. Furthermore, a cell temperature control strategy is developed with respect to the constraints of a refrigerant-based battery cooling unit. The data obtained from the simulation demonstrate the high thermal inertia of the system and suggest sufficient control of the battery temperature using a quasi-stationary cooling strategy. Thereby, the study reveals a crucial design input for battery cooling systems in terms of heat transfer behavior and control strategy.
Solf, Benjamin; Schramm, Stefan; Blum, Maren-Christina; Klee, Sascha;
The influence of the stimulus design on the harmonic components of the steady-state visual evoked potential. - In: Frontiers in human neuroscience, ISSN 1662-5161, Bd. 14 (2020), 343, insges. 11 S.
Weidner, Florian; Broll, Wolfgang;
Stereoscopic 3D dashboards : an investigation of performance, workload, and gaze behavior during take-overs in semi-autonomous driving. - In: Personal and ubiquitous computing, ISSN 1617-4917, (2020), insges. 23 S.
Published: 25 August 2020

When operating a conditionally automated vehicle, humans occasionally have to take over control. If the driver is out of the loop, a certain amount of time is necessary to gain situation awareness. This work evaluates the potential of stereoscopic 3D (S3D) dashboards for presenting smart S3D take-over-requests (TORs) to support situation assessment. In a driving simulator study with a 4 × 2 between-within design, we presented 3 smart TORs showing the current traffic situation and a baseline TOR in 2D and S3D to 52 participants doing the n-back task. We further investigate if non-standard locations affect the results. Take-over performance indicates that participants looked at and processed the TORs' visual information and by that, could perform more safe take-overs. S3D warnings in general, as well as warnings appearing at the participants focus of attention and warnings at the instrument cluster, performed best. We conclude that visual warnings, presented on an S3D dashboard, can be a valid option to support take-over while not increasing workload. We further discuss participants gaze behavior in the context of visual warnings for automotive user interfaces.
Lasch, Robert; Oukid, Ismail; Dementiev, Roman; May, Norman; Demirsoy, Suleyman S.; Sattler, Kai-Uwe;
Faster & strong: string dictionary compression using sampling and fast vectorized decompression. - In: The VLDB journal, ISSN 0949-877X, Bd. 29 (2020), 6, S. 1263-1285

String dictionaries constitute a large portion of the memory footprint of database applications. While strong string dictionary compression algorithms exist, these come with impractical access and compression times. Therefore, lightweight algorithms such as front coding (PFC) are favored in practice. This paper endeavors to make strong string dictionary compression practical. We focus on Re-Pair Front Coding (RPFC), a grammar-based compression algorithm, since it consistently offers better compression ratios than other algorithms in the literature. To accelerate compression times, we propose block-based RPFC (BRPFC) which consists in independently compressing small blocks of the dictionary. For further accelerated compression times especially on large string dictionaries, we also propose an alternative version of BRPFC that uses sampling to speed up compression. Moreover, to accelerate access times, we devise a vectorized access method, using Intel® Advanced Vector Extensions 512 (Intel® AVX-512). Our experimental evaluation shows that sampled BRPFC offers compression times up to 190 × faster than RPFC, and random string lookups 2.3 × faster than RPFC on average. These results move our modified RPFC into a practical range for use in database systems because the overhead of Re-Pair-based compression for access times can be reduced by 2 ×.
Al-Sayeh, Hani; Hagedorn, Stefan; Sattler, Kai-Uwe;
A gray-box modeling methodology for runtime prediction of Apache Spark jobs. - In: Distributed and parallel databases, ISSN 1573-7578, Bd. 38 (2020), 4, S. 819-839

Apache Spark jobs are often characterized by processing huge data sets and, therefore, require runtimes in the range of minutes to hours. Thus, being able to predict the runtime of such jobs would be useful not only to know when the job will finish, but also for scheduling purposes, to estimate monetary costs for cloud deployment, or to determine an appropriate cluster configuration, such as the number of nodes. However, predicting Spark job runtimes is much more challenging than for standard database queries: cluster configuration and parameters have a significant performance impact and jobs usually contain a lot of user-defined code making it difficult to estimate cardinalities and execution costs. In this paper, we present a gray-box modeling methodology for runtime prediction of Apache Spark jobs. Our approach comprises two steps: first, a white-box model for predicting the cardinalities of the input RDDs of each operator is built based on prior knowledge about the behavior and application parameters such as applied filters data, number of iterations, etc. In the second step, a black-box model for each task constructed by monitoring runtime metrics while varying allocated resources and input RDD cardinalities is used. We further show how to use this gray-box approach not only for predicting the runtime of a given job, but also as part of a decision model for reusing intermediate cached results of Spark jobs. Our methodology is validated with experimental evaluation showing a highly accurate prediction of the actual job runtime and a performance improvement if intermediate results can be reused.
Stöhr, Annika; Budzinski, Oliver; Jasper, Jörg;
The New E.ON on the German electricity market - competitive impact of the innogy acquisition :
Die Neue E.ON auf dem deutschen Strommarkt - wettbewerbliche Auswirkungen der innogy-Übernahme. - In: List Forum für Wirtschafts- und Finanzpolitik, ISSN 2364-3943, Bd. 45 (2020), 3, S. 295-317

Der Deal der beiden größten deutschen Energielieferanten RWE und E.ON zum Tausch verschiedener Geschäftseinheiten, welcher Mitte September 2019 genehmigt wurde, wird den deutschen Energiemarkt wesentlich umstrukturieren und sowohl im Bereich Erzeugung als auch im Vertrieb zu jeweils einem dominanten Wettbewerber führen. E.ON wird dabei durch die Übernahme der innogy Geschäfte im Bereich des klassischen Energievertriebs und der Ladeinfrastruktur für Elektrofahrzeuge wesentliche Wettbewerbsvorteile erhalten. Dazu zählt unter anderem der Zugang zu einer Vielzahl an Messstellen und damit Datensätzen im Bereich des Haushalts- und Geschäftskundenvertriebs. Die Auswertung und Nutzung dieser Datensätze eröffnet dem zusammengeschlossenen Unternehmen neue Geschäftsfelder, aber auch Möglichkeiten die dominante Stellung auf dem Markt zu missbrauchen. Dieser Beitrag widmet sich den potenziellen Auswirkungen der innogy-Übernahme durch E.ON in den Bereichen klassischer Vertrieb und EMobilität, in welchen die angesprochenen Aspekte der Datenökonomik eine wesentliche Rolle spielen. Des Weiteren werden die Auswirkungen der Marktumstrukturierung auf den Konzessionsmarkt betrachtet und die politökonomische Dimension des Zusammenschlusses erläutert. Wir schließen mit einer Kurzanalyse der Erlaubnisentscheidung und der damit verbundenen Auflagen und kommen zu dem Schluss, dass diese nicht geeignet sind, die erheblichen anti-kompetitiven Auswirkungen des Zusammenschlusses einzudämmen oder zu verhindern.
Zhang, Chenglin; Xu, Yang; He, Kaiming; Dong, Yulian; Zhao, Huaping; Medenbach, Lukas; Wu, Yuhan; Balducci, Andrea; Hannappel, Thomas; Lei, Yong;
Polyimide@Ketjenblack composite: a porous organic cathode for fast rechargeable potassium-ion batteries. - In: Small, ISSN 1613-6829, Bd. 16 (2020), 38, 2002953, insges. 8 S.

Potassium-ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium-ion batteries. Here, a porous organic PolyimideKetjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g^-1 at 100 mA g^-1), high rate capability (125 and 105 mAh g^-1 at 1000 and 5000 mA g^-1), and long cycling stability (76% capacity retention at 2000 mA g^-1 over 1000 cycles). The domination of fast capacitive-like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization. Moreover, a renewable and low-cost full cell is demonstrated with superior rate behavior (106 mAh g^-1 at 3200 mA g^-1). This work proposes a strategy to design polymer electrodes for high-performance organic PIBs.
Gruia, Violeta-Tincuta; Ispas, Adriana; Efimov, Igor; Bund, Andreas;
Cation exchange behavior during the redox switching of poly (3,4-ethylenedioxythiophene) films. - In: Journal of solid state electrochemistry, ISSN 1433-0768, Bd. 24 (2020), 11/12, S. 3231-3244

Poly (3,4-ethylenedioxythiophene), PEDOT, films were synthesized at room temperature by potentiodynamic and potentiostatic step deposition in aqueous solutions containing EDOT monomer and LiClO4. In some solutions, the effect of small amounts of sodium dodecylsulfate, SDS, on the polymerization rate of EDOT and on the stiffness of the obtained PEDOT film was studied. The obtained PEDOT films were transferred in aqueous solutions containing cations with different molar mass, such as H+, Li+, Na+, K+, and Cs+. The apparent molar masses of the exchanged species during potentiodynamic experiments were determined by in situ microgravimetry. These measurements underlined the importance of the electrolyte chosen for electropolymerization process. It is known that SDS anions can be trapped inside the polymer layer during electropolymerization, providing them with a cation exchange behavior. However, even if the PEDOT films were deposited from an electrolyte without SDS, they still acted as cation exchangers.
Semper, Sebastian; Döbereiner, Michael; Pawar, Sankalp; Landmann, Markus; Del Galdo, Giovanni;
eadf: representation of far-field antenna responses in Python. - In: SoftwareX, ISSN 2352-7110, Bd. 12 (2020), 100583, S. 1-6
Kuznietsova, Halyna; Dziubenko, Natalia; Herheliuk, Tetiana; Prylutskyy, Yuriy; Täuscher, Eric; Ritter, Uwe; Scharff, Peter;
Water-soluble pristine C60 fullerene inhibits liver alterations associated with hepatocellular carcinoma in rat. - In: Pharmaceutics, ISSN 1999-4923, Volume 12 (2020), issue 9, 794, Seite 1-20
Richtiger Name des Verfassers: Eric Täuscher
Schweitzer, Dietrich; Haueisen, Jens; Brauer, Jakob Lauritz; Hammer, Martin; Klemm, Matthias;
Comparison of algorithms to suppress artifacts from the natural lens in fluorescence lifetime imaging ophthalmoscopy (FLIO). - In: Biomedical optics express, ISSN 2156-7085, Bd. 11 (2020), 10, S. 5586-5602
Schricker, Klaus; Ganß, Martin; Könke, Carsten; Bergmann, Jean Pierre;
Feasibility study of using integrated fiber optical sensors to monitor laser-assisted metal-polymer joining. - In: Welding in the world, ISSN 1878-6669, Bd. 64 (2020), 9, S. 1565-1578

The possibilities and challenges of using fiber optical sensors to monitor the laser-assisted joining of metal-polymer joints have been described in this article. Fundamental investigation proves the basic suitability of the measuring method for this application and studies the effect of essential influencing variables of the joining process - e.g., the clamping force - on the resulting sensor signals. In addition, the strain state (because of the process temperature and shrinkage of the polymer) of the parts to be joined can be traced as a function of the joining partners, the process parameters, and the material thicknesses. It is shown that the fiber optical method is suitable for process monitoring directly in the joining zone of metal-polymer hybrids and providing a tool for detailed strain measurements in the joint zone during subsequent component testing.
Köhler, Michael; Beetz, Nancy; Günther, Mike; Möller, Frances; Schüler, Tim; Cao, Jialan;
Microbial community types and signature-like soil bacterial patterns from fortified prehistoric hills of Thuringia (Germany). - In: Community ecology, ISSN 1588-2756, Bd. 21 (2020), 2, S. 107-120

16S rRNA profiling has been applied for the investigation of bacterial communities of surface soil samples from forest-covered areas of ten prehistorical ramparts from different parts of Thuringia. Besides the majority bacterial types that are present in all samples, there could be identified bacteria that are highly abundant in some places and absent or low abundant in others. These differences are mainly related to the acidity of substrate and distinguish the communities of lime stone hills from soils of sand/quartzite and basalt hills. Minority components of bacterial communities show partially large differences that cannot be explained by the pH of the soil or incidental effects, only. They reflect certain relations between the communities of different places and could be regarded as a kind of signature-like patterns. Such relations had also been found in a comparison of the data from ramparts with formerly studied 16S rRNA profiling from an iron-age burial field. The observations are supporting the idea that a part of the components of bacterial communities from soil samples reflect their ecological history and can be understood as the "ecological memory" of a place. Probably such memory effects can date back to prehistoric times and might assist in future interpretations of archaeological findings on the prehistoric use of a place, on the one hand. On the other hand, the genetic profiling of soils of prehistoric places contributes to the evaluation of anthropogenic effects on the development of local soil bacterial diversity.
Halm, Cynthia; Otto, Andreas; Stark, Tilman; Schaaf, Peter;
Ultrasonic excitation during press-fit joining of electrical contacts. - In: The international journal of advanced manufacturing technology, ISSN 1433-3015, Bd. 109 (2020), 7/8, S. 2215-2220
Budzinski, Oliver; Grebel, Thomas; Wolling, Jens; Zhang, Xijie;
Drivers of article processing charges in open access. - In: Scientometrics, ISSN 1588-2861, Bd. 124 (2020), 3, S. 2185-2206
Döring, Nicola; Mohseni, Rohangis; Walter, Roberto;
Design, use, and effects of sex dolls and sex robots: scoping review. - In: Journal of medical internet research, ISSN 1438-8871, Vol. 22 (2020), no. 7, e18551, p. 1-28
Bang-Jensen, Jørgen; Bellitto, Thomas; Schweser, Thomas; Stiebitz, Michael;
On DP-coloring of digraphs. - In: Journal of graph theory, ISSN 1097-0118, Bd. 95 (2020), 1, S. 76-98
Jaziri, Nesrine; Boughamoura, Ayda; Müller, Jens; Mezghani, Brahim; Tounsi, Fares; Ismail, Mohammed;
A comprehensive review of thermoelectric generators: technologies and common applications. - In: Energy reports, ISSN 2352-4847, Bd. 6 (2020), S. 264-287
Damanik, Ferdinandus Sarjanadi; Lange, Günther;
Influence of MWCNT coated nickel on the foaming behavior of MWCNT coated nickel reinforced AlMg4Si8 foam by powder metallurgy process. - In: Metals, ISSN 2075-4701, Bd. 10 (2020), 7, 955, insges. 9 S.

This research studies the effect of multi-wall carbon nanotube (MWCNT) coated nickel to foaming time on the foam expansion and the distribution of pore sizes MWCNT reinforced AlMg4Si8 foam composite by powder metallurgy process. To control interface reactivity and wettability between MWCNT and the metal matrix, nickel coating is carried out on the MWCNT surface. Significantly, different foaming behavior of the MWCNT coated nickel reinforced AlMg4Si8 was studied with a foaming time variation of 8 and 9 min. Digital images generated by the imaging system are used with the MATLAB R2017a algorithm to determine the porosity of the surface and the pore area of aluminum foam efficiently. The results can have important implications for processing MWCNT coated nickel reinforced aluminum alloy composites.
Wang, Hongmei; Xiong, Jie; Cheng, Xing; Chen, Ge; Kups, Thomas; Wang, Dong; Schaaf, Peter;
Hydrogen-nitrogen plasma assisted synthesis of titanium dioxide with enhanced performance as anode for sodium ion batteries. - In: Scientific reports, ISSN 2045-2322, Bd. 10 (2020), 11817, insges. 12 S.
Blum, Maren-Christina; Hunold, Alexander; Solf, Benjamin; Klee, Sascha;
The effects of an ocular direct electrical stimulation on pattern-reversal electroretinogram. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 14 (2020), 588, S. 1-9
Pezoldt, Jörg; Cimalla, Volker;
Imprinting the polytype structure of silicon carbide by rapid thermal processing. - In: Crystals, ISSN 2073-4352, Volume 10 (2020), issue 6, 523, 21 Seiten
Du Puits, Ronald; Bruecker, Christoph;
Fluctuations of the wall shear stress vector in a large-scale natural convection cell. - In: AIP Advances, ISSN 2158-3226, Bd. 10 (2020), 7, 075105, insges. 10 S.
Gierth, Maximilian; Henckell, Philipp; Ali, Yarop; Scholl, Jonas; Bergmann, Jean Pierre;
Wire arc additive manufacturing (WAAM) of aluminium alloy AlMg5Mn with energy-reduced gas metal arc welding (GMAW). - In: Materials, ISSN 1996-1944, Bd. 13 (2020), 12, 2671, insges. 22 S.
Cao, Jialan; Richter, Felix; Kastl, Michael; Erdmann, Jonny; Burgold, Christian; Dittrich, David; Schneider, Steffen; Köhler, Michael; Groß, Gregor Alexander;
Droplet-based screening for the investigation of microbial nonlinear dose-response characteristics system, background, and examples. - In: Micromachines, ISSN 2072-666X, Bd. 11 (2020), 6, 577, insges. 19 S.
Adekitan, Aderibigbe Israel;
A new definition of voltage unbalance using supply phase shift. - In: Journal of control, automation and electrical systems, ISSN 2195-3899, Bd. 31 (2020), 3, S. 718-725
Cretu, Andrea; Mattea, Carlos; Stapf, Siegfried; Ardelean, Ioan;
The effect of silica fume and organosilane addition on the porosity of cement paste. - In: Molecules, ISSN 1420-3049, Volume 25 (2020), issue 8, 1762, Seite 1-9
Henckell, Philipp; Gierth, Maximilian; Ali, Yarop; Reimann, Jan; Bergmann, Jean Pierre;
Reduction of energy input in wire arc additive manufacturing (WAAM) with gas metal arc welding (GMAW). - In: Materials, ISSN 1996-1944, Bd. 13 (2020), 11, 2491, insges. 18 S.
Dutz, Silvio; Buske, Norbert; Landers, Joachim; Gräfe, Christine; Wende, Heiko; Clement, Joachim H.;
Biocompatible magnetic fluids of Co-doped iron oxide nanoparticles with tunable magnetic properties. - In: Nanomaterials, ISSN 2079-4991, Volume 10 (2020), issue 6, 1019, Seite 1-19
Kielpinski, Mark; Walther, Oliver; Cao, Jialan; Henkel, Thomas; Köhler, Michael; Groß, Gregor Alexander;
Microfluidic chamber design for controlled droplet expansion and coalescence. - In: Micromachines, ISSN 2072-666X, Bd. 11 (2020), 4, 394, insges. 16 S.
Naskovska, Kristina; Lau, Stephan; Korobkov, Alexey A.; Haueisen, Jens; Haardt, Martin;
Coupled CP decomposition of simultaneous MEG-EEG signals for differentiating oscillators during photic driving. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 14 (2020), 261, S. 1-18
Weise, Konstantin; Poßner, Lucas; Müller, Erik; Gast, Richard; Knösche, Thomas R.;
Pygpc: a sensitivity and uncertainty analysis toolbox for Python. - In: SoftwareX, ISSN 2352-7110, Bd. 11 (2020), 100450, S. 1-6
Moller, Sebastian; Resagk, Christian; Cierpka, Christian;
On the application of neural networks for temperature field measurements using thermochromic liquid crystals. - In: Experiments in fluids, ISSN 1432-1114, Bd. 61 (2020), 4, 111, insges. 21 S.

This study presents an investigation regarding the applicability of neural networks for temperature measurements using thermochromic liquid crystals (TLCs) and discusses advantages as well as disadvantages of common calibration approaches. For the characterization of the measurement technique, the dependency of the color of the TLCs on the temperature as well as on the observation angle and, therefore, on the position within the field of view of a color camera is analyzed in detail. In order to consider the influence of the position within the field of view on the color, neural networks are applied for the calibration of the temperature measurements. In particular, the focus of this study is on analysis of the error of temperature measurement for different network configurations as well as training methods, yielding a mean absolute deviation and a mean standard deviation in the range of 0.1 K for instantaneous measurements. On the basis of a comparison of this standard deviation to that of two further calibration approaches, it is shown that neural networks are suited for temperature measurements via the color of TLCs. Finally, the applicability of this measurement technique is illustrated at an exemplary temperature measurement in a horizontal plane of a Rayleigh-Bénard cell with large aspect ratio, which clearly shows the emergence of convective flow patterns by means of the temperature field.
Kostochka, Alexandr V.; Stiebitz, Michael;
The minimum number of edges in 4-critical digraphs of given order. - In: Graphs and combinatorics, ISSN 1435-5914, Bd. 36 (2020), 3, S. 703-718
Kröger, Jörg; Néel, Nicolas; Wehling, Tim O.; Brandbyge, Mads;
Local probes of graphene lattice dynamics. - In: Small Methods, ISSN 2366-9608, Volume 4 (2020), issue 5, 1900817, 18 Seiten
Ghoshal, Sushanta; Mattea, Carlos; Denner, Paul; Stapf, Siegfried;
Effect of initial conformation on the starch biopolymer film formation studied by NMR. - In: Molecules, ISSN 1420-3049, Volume 25 (2020), issue 5, 1227, Seite 1-17
Heinemann, David; Dutz, Silvio; Knabner, Steffen; Haueisen, Jens; Baumgarten, Daniel;
Camera calibration and orientation for PCB jet printing inspection. - In: SN applied sciences, ISSN 2523-3971, Bd. 2 (2020), 3, 322, insges. 14 S.
Kronfeld, Klaus-Peter; Ellinger, Thomas; Köhler, Michael;
Microfluidically prepared sensor particles for determination of chloride by fluorescence quenching of matrix-embedded lucigenin. - In: SN applied sciences, ISSN 2523-3971, Bd. 2 (2020), 3, 366, insges. 8 S.
Stauffenberg, Jaqueline; Durstewitz, Steve; Hofmann, Martin; Ivanov, Tzvetan; Holz, Mathias; Ehrhardt, Waleed; Riegel, Wolf-Ulrich; Zöllner, Jens-Peter; Manske, Eberhard; Rangelow, Ivo W.;
Determination of the mixing ratio of a flowing gas mixture with self-actuated microcantilevers. - In: Journal of sensors and sensor systems, ISSN 2194-878X, Bd. 9 (2020), 1, S. 71-78
Leimbach, Martin; Tschaar, Christoph; Schmidt, Udo; Bund, Andreas;
Low-frequency pulse plating for tailoring the optical appearance of chromium layers for decorative applications. - In: Journal of applied electrochemistry, ISSN 1572-8838, Bd. 50 (2020), 4, S. 489-499
Yan, Chengzhan; Zhao, Huaping; Li, Jun; Jin, Huile; Liu, Long; Wu, Wanyi; Wang, Jichang; Lei, Yong; Wang, Shun;
Mild-temperature solution-assisted encapsulation of phosphorus into ZIF-8 derived porous carbon as lithium-ion battery anode. - In: Small, ISSN 1613-6829, Bd. 16 (2020), 11, 1907141, insges. 7 S.
Krey, Maximilian; Hähnlein, Bernd; Tonisch, Katja; Krischok, Stefan; Töpfer, Hannes;
Automated parameter extraction of ScAlN MEMS devices using an extended Euler-Bernoulli beam theory. - In: Sensors, ISSN 1424-8220, Bd. 20 (2020), 4, 1001, insges. 19 S.
Müller, Steffen; Wengefeld, Tim; Trinh, Thanh Quang; Aganian, Dustin; Eisenbach, Markus; Groß, Horst-Michael;
A multi-modal person perception framework for socially interactive mobile service robots. - In: Sensors, ISSN 1424-8220, Bd. 20 (2020), 3, 722, insges. 18 S.
Bach, Norbert; Galvin, Peter;
A third dimension in the mirror? How senior managers design products and organizations. - In: Strategic change, ISSN 1099-1697, Bd. 29 (2020), 1, S. 25-33
Janke, Mario; Kuschke, Tobias; Mäder, Patrick;
A definition-by-example approach and visual language for activity patterns in engineering disciplines. - In: PLOS ONE, ISSN 1932-6203, Bd. 15 (2020), 1, e0226877, insges. 28 S.
Sauerteig, Philipp; Worthmann, Karl;
Towards multiobjective optimization and control of smart grids. - In: Optimal control, applications and methods, ISSN 1099-1514, Bd. 41 (2020), 1, S. 128-145
Böttcher, René; Ispas, Adriana; Bund, Andreas;
Anodic dissolution of aluminum and anodic passivation in [EMIm]Cl-based ionic liquids. - In: Electrochemistry communications, ISSN 1873-1902, Bd. 115 (2020), 106720, S. 1-6
Zeidis, Igor; Zimmermann, Klaus;
Dynamics of a four-wheeled mobile robot with Mecanum wheels. - In: ZAMM, ISSN 1521-4001, Volume 99 (2019), issue 12, e201900173, 22 Seiten
Editor's choice
Dupleich, Diego; Müller, Robert; Landmann, Markus; Shinwasusin, Ek-Amorn; Saito, Kentaro; Takada, Jun-ichi; Luo, Jian; Thomä, Reiner; Del Galdo, Giovanni;
Multi-band propagation and radio channel characterization in street canyon scenarios for 5G and beyond. - In: IEEE access, ISSN 2169-3536, Bd. 7 (2019), S. 160385-160396
Freitag, Stefanie; Hunold, Alexander; Klemm, Matthias; Klee, Sascha; Link, Dietmar; Nagel, Edgar; Haueisen, Jens;
Pulsed electrical stimulation of the human eye enhances retinal vessel reaction to flickering light. - In: Frontiers in human neuroscience, ISSN 1662-5161, Bd. 13 (2019), 371, insges. 11 S.
Machts, René; Hunold, Alexander; Drebenstedt, Christian; Rock, Michael; Leu, Carsten; Haueisen, Jens;
Measurement and analysis of partial lightning currents in a head phantom. - In: PLOS ONE, ISSN 1932-6203, Bd. 14 (2019), 9, e0223133, insges. 22 S.
Köhler, Michael; Kluitmann, Jonas; Knauer, Andrea;
Metal nano networks by potential-controlled in situ assembling of gold/silver nanoparticles. - In: ChemistryOpen, ISSN 2191-1363, Bd. 8 (2019), 12, S. 1369-1374
Scharff, Moritz; Schorr, Philipp; Becker, Tatiana; Resagk, Christian; Alencastre Miranda, Jorge H.; Behn, Carsten;
An artificial vibrissa-like sensor for detection of flows. - In: Sensors, ISSN 1424-8220, Bd. 19 (2019), 18, 3892, insges. 16 S.

In nature, there are several examples of sophisticated sensory systems to sense flows, e.g., the vibrissae of mammals. Seals can detect the flow of their prey, and rats are able to perceive the flow of surrounding air. The vibrissae are arranged around muzzle of an animal. A vibrissa consists of two major components: a shaft (infector) and a follicle-sinus complex (receptor), whereby the base of the shaft is supported by the follicle-sinus complex. The vibrissa shaft collects and transmits stimuli, e.g., flows, while the follicle-sinus complex transduces them for further processing. Beside detecting flows, the animals can also recognize the size of an object or determine the surface texture. Here, the combination of these functionalities in a single sensory system serves as paragon for artificial tactile sensors. The detection of flows becomes important regarding the measurement of flow characteristics, e.g., velocity, as well as the influence of the sensor during the scanning of objects. These aspects are closely related to each other, but, how can the characteristics of flow be represented by the signals at the base of a vibrissa shaft or by an artificial vibrissa-like sensor respectively? In this work, the structure of a natural vibrissa shaft is simplified to a slender, cylindrical/tapered elastic beam. The model is analyzed in simulation and experiment in order to identify the necessary observables to evaluate flows based on the quasi-static large deflection of the sensor shaft inside a steady, non-uniform, laminar, in-compressible flow.
Kirchhoff, Michael; Kerling, Philipp; Streitferdt, Detlef; Fengler, Wolfgang;
A real-time capable dynamic partial reconfiguration system for an application-specific soft-core processor. - In: International journal of reconfigurable computing, ISSN 1687-7209, Volume 2019, article ID 4723838, 14 pages
Rochyadi-Reetz, Mira; Arlt, Dorothee; Wolling, Jens; Bräuer, Marco;
Explaining the media's framing of renewable energies: an international comparison. - In: Frontiers in Environmental Science, ISSN 2296-665X, Volume 7 (2019), article 119, Seite 1-12
Kaltwasser, Masha; Schmidt, Udo; Lösing, Lars; Biswas, Shantonu; Stauden, Thomas; Bund, Andreas; Jacobs, Heiko O.;
Fluidic self-assembly on electroplated multilayer solder bumps with tailored transformation imprinted melting points. - In: Scientific reports, ISSN 2045-2322, Bd. 9 (2019), 11325, insges. 8 S.
Graichen, Uwe; Eichardt, Roland; Haueisen, Jens;
SpharaPy: a Python toolbox for spatial harmonic analysis of non-uniformly sampled data. - In: SoftwareX, ISSN 2352-7110, Bd. 10 (2019), 100289, S. 1-7
Cao, Hao; Hopfgarten, Siegbert; Ostfeld, Avi; Salomons, Elad; Li, Pu;
Simultaneous sensor placement and pressure reducing valve localization for pressure control of water distribution systems. - In: Water, ISSN 2073-4441, Volume 11 (2019), issue 7, 1352, Seite 1-18
Podkurkov, Ivan; Zhang, Jianshu; Nadeev, Adel Firadovich; Haardt, Martin;
Efficient multidimensional wideband parameter estimation for OFDM based joint radar and communication systems. - In: IEEE access, ISSN 2169-3536, Bd. 7 (2019), S. 112792-112808
Singh, Jasmeet; Stephan, Ralf; Hein, Matthias;
Low-profile penta-band automotive patch antenna using horizontal stacking and corner feeding. - In: IEEE access, ISSN 2169-3536, Bd. 7 (2019), S. 74198-74205
Rath, Michael; Mäder, Patrick;
The SEOSS 33 dataset - requirements, bug reports, code history, and trace links for entire projects. - In: Data in Brief, ISSN 2352-3409, Volume 25 (2019), article 104005, Seite 1-12
Thomann, Jana; Eichfelder, Gabriele;
Numerical results for the multiobjective trust region algorithm MHT. - In: Data in Brief, ISSN 2352-3409, Volume 25 (2019), article 104103, Seite 1-18
Häfner, Stephan; Käske, Martin; Thomä, Reiner;
On calibration and direction finding with uniform circular arrays. - In: International journal of antennas and propagation, ISSN 1687-5877, (2019), Article ID 1523469, Seite 1-12
Lenk, Leonhard; Mitschunas, Beate; Sinzinger, Stefan;
Zoom systems with tunable lenses and linear lens movements. - In: Journal of the European Optical Society, ISSN 1990-2573, Bd. 15 (2019), 9, insges. 10 S.

Background: Classical zoom lenses are based on movements of sub-modules along the optical axis. Generally, a constant image plane position requires at least one nonlinear sub-module movement. This nonlinearity poses a challenge for the mechanical implementation. Tuneable lenses can change their focal length without moving along the optical axis. This offers the possibility of small system lengths. Since the focal range of tuneable lenses with significant aperture diameters is still limited, the use of tuneable optics in zoom lenses is usually restricted to miniaturized applications. Methods: To solve the challenge of the nonlinear movement in classical zoom lenses and the limitations of tuneable lenses for macroscopic applications we propose a combination of both concepts. The resulting 'Hybrid Zoom Lens' involves linear movements of sub modules as well as changing the focal length of a tuneable lens. The movements of the sub-modules and the focal length tuning of the lens are already determined by the collinear layout of the zoom lens. Therefore, we focus on collinear considerations and develop a method that allows a targeted choice of specific collinear layouts for our 'Hybrid zoom lenses'. Results: Based on examples and an experimental setup we demonstrate the feasibility of our approach. We apply the proposed method to examples of classical zoom lenses and zoom lenses based exclusively on tuneable lenses. Thereby we are able to show possible advantages of our 'Hybrid zoom lenses' over these widespread system types. Conclusions: We demonstrate important collinear considerations for the integration of tuneable lenses into a zoom lens. We show that the combination of classical zoom lens concepts with tuneable lenses offers the possibility to reach smaller system lengths for macroscopic zoom lenses while requiring only a small focal tuning range of the tuneable lens.
Henckell, Philipp; Ali, Yarop; Metz, Andreas; Bergmann, Jean Pierre; Reimann, Jan;
In situ production of titanium aluminides during wire arc additive manufacturing with hot-wire assisted GMAW process. - In: Metals, ISSN 2075-4701, Bd. 9 (2019), 5, 578, insges. 13 S.
Augustin, Silke; Fröhlich, Thomas;
Temperature dependence of dynamic parameters of contact thermometers. - In: Sensors, ISSN 1424-8220, Bd. 19 (2019), 10, 2299, insges. 9 S.
Link, Steffen; Ivanov, Svetlozar; Dimitrova, Anna; Krischok, Stefan; Bund, Andreas;
Electrochemical deposition of silicon from a sulfolane-based electrolyte: effect of applied potential. - In: Electrochemistry communications, ISSN 1873-1902, Bd. 103 (2019), S. 7-11
Ley, Sebastian; Schilling, Susanne; Fiser, Ondrej; Vrba, Jan; Sachs, Jürgen; Helbig, Marko;
Ultra-wideband temperature dependent dielectric spectroscopy of porcine tissue and blood in the microwave frequency range. - In: Sensors, ISSN 1424-8220, Bd. 19 (2019), 7, 1707, insges. 21 S.
Solf, Benjamin; Schramm, Stefan; Link, Dietmar; Klee, Sascha;
Objective measurement of forward-scattered light in the human eye: an electrophysiological approach. - In: PLOS ONE, ISSN 1932-6203, Bd. 14 (2019), 4, e0214850, insges. 14 S.
Linß, Sebastian; Henning, Stefan; Zentner, Lena;
Modeling and design of flexure hinge-based compliant mechanisms. - In: Kinematics, (2019), S. 1-24

A compliant mechanism gains its mobility fully or partially from the compliance of its elastically deformable parts rather than from conventional joints. Due to many advantages, in particular the smooth and repeatable motion, monolithic mechanisms with notch flexure hinges are state of the art in numerous precision engineering applications with required positioning accuracies in the low micrometer range. However, the deformation and especially motion behavior are complex and depend on the notch geometry. This complicates both the accurate modeling and purposeful design. Therefore, the chapter provides a survey of different methods for the general and simplified modeling of the elasto-kinematic properties of flexure hinges and compliant mechanisms for four hinge contours. Based on non-linear analytical calculations and FEM simulations, several guidelines like design graphs, design equations, design tools or a geometric scaling approach are presented. The obtained results are analytically and simulatively verified and show a good correlation. Using the example of a path-generating mechanism, it will be demonstrated that the suggested angle-based method for synthesizing a compliant mechanism with individually shaped hinges can be used to design high-precise and large-stroke compliant mechanisms. The approaches can be used for the accelerated synthesis of planar and spatial flexure hinge-based compliant mechanisms.
Berger, Priscila; Wolling, Jens;
They need more than technology-equipped schools: teachers' practice of fostering students' digital protective skills. - In: Media and communication, ISSN 2183-2439, Bd. 7 (2019), 2, S. 137-147
Berlt, Philipp; Jäger, Lisa; Schwind, Andreas; Wollenschläger, Frank; Bornkessel, Christian; Hein, Matthias;
Over-the-air testing of automotive antennas and wireless links in the installed state on the basis of LTE downlink communication parameters. - In: Advances in science, technology and engineering systems journal, ISSN 2415-6698, Bd. 4 (2019), 1, S. 282-291
Sewalkar, Parag; Seitz, Jochen;
Vehicle-to-Pedestrian communication for vulnerable road users: survey, design considerations, and challenges. - In: Sensors, ISSN 1424-8220, Bd. 19 (2019), 2, 358, insges. 18 S.
Klemm, Matthias; Sauer, Lydia; Klee, Sascha; Link, Dietmar; Peters, Sven; Hammer, Martin; Schweitzer, Dietrich; Haueisen, Jens;
Bleaching effects and fluorescence lifetime imaging ophthalmoscopy. - In: Biomedical optics express, ISSN 2156-7085, Bd. 10 (2019), 3, S. 1446-1461
Seeland, Marco; Rzanny, Michael Carsten; Boho, David; Wäldchen, Jana; Mäder, Patrick;
Image-based classification of plant genus and family for trained and untrained plant species. - In: BMC bioinformatics, ISSN 1471-2105, Bd. 20 (2019), (3. Jan.), Article 4, insges. 13 S.
Wuttke, Heinz-Dietrich; Parkhomenko, Anzhelika; Tulenkov, Artem; Tabunshchyk, Galyna; Parkhomenko, Andriy; Henke, Karsten;
The remote experimentation as the practical-oriented basis of inclusive engineering education. - In: International journal of online and biomedical engineering, ISSN 2626-8493, Bd. 15 (2019), 5, S. 4-17
Henning, Stefan; Linß, Sebastian; Zentner, Lena;
detasFLEX - a computational design tool for the analysis of various notch flexure hinges based on non-linear modeling. - In: Mechanical sciences, ISSN 2191-916X, Bd. 9 (2018), 2, S. 389-404

A novel computational design tool to calculate the elasto-kinematic flexure hinge properties is presented. Four hinge contours are implemented. It is shown, that FEM results correlate well with the analytical design tool results. For a given deflection angle of 10˚ and a corner-filleted contour, the deviations of the bending stiffness are between 0.1 % and 9.4 %. The design tool can be beneficial for the accelerated and systematic synthesis of compliant mechanisms with optimized flexure hinges.
Krug, Silvia; Aumüller, Matthias; Seitz, Jochen;
Hybrid scheme to enable DTN routing protocols to efficiently exploit stable MANET contacts. - In: EURASIP journal on wireless communications and networking, ISSN 1687-1499, (2018), 237, S. 1-13
Sousa, Marcelo Nogueira de; Thomä, Reiner;
Enhancement of localization systems in NLOS urban scenario with multipath ray tracing fingerprints and machine learning. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 11, 4073, insges. 30 S.
Mattern, Anne; Sandig, Romy; Joos, Alexander; Löwa, Norbert; Kosch, Olaf; Weidner, Andreas; Wells, James; Wiekhorst, Frank; Dutz, Silvio;
Magnetic nanoparticle-gel materials for development of joint phantoms for MPI and MRI. - In: International journal on magnetic particle imaging, ISSN 2365-9033, Vol. 4 (2018), no. 2, article ID 1811001, Seite 1-5
Bartsch, Heike; Peipmann, Ralf; Klett, Maren; Brauer, Dana; Schober, Andreas; Müller, Jens;
PEDOT coated thick film electrodes for in situ detection of cell adhesion in cell cultures. - In: Biosensors, ISSN 2079-6374, Bd. 8 (2018), 4, 105, insges. 13 S.
Shirichian, Mehdi; Chamaani, Somayyeh; Akbarpour, Alireza; Del Galdo, Giovanni;
Analysis and design of broadband simultaneous wireless information and power transfer (SWIPT) system considering rectifier effect. - In: Energies, ISSN 1996-1073, Bd. 11 (2018), 9, 2387, insges. 18 S.
Steidl, Matthias; Wu, Mingjian; Peh, Katharina; Kleinschmidt, Peter; Spiecker, Erdmann; Hannappel, Thomas;
Impact of N incorporation on VLS growth of GaP(N) nanowires utilizing UDMH. - In: Nanoscale research letters, ISSN 1556-276X, Bd. 13 (2018), Article 417, insges. 9 S.
Bartsch, Heike; Grieseler, Rolf; Mánuel, Jose; Pezoldt, Jörg; Müller, Jens;
Magnetron sputtered AlN layers on LTCC multilayer and silicon substrates. - In: Coatings, ISSN 2079-6412, Bd. 8 (2018), 8, 289, insges. 19 S.
Rieger, Steffen; Klee, Sascha; Baumgarten, Daniel;
Experimental characterization and correlation of Mayer waves in retinal vessel diameter and arterial blood pressure. - In: Frontiers in physiology, ISSN 1664-042X, Bd. 9 (2018), Article 892, insges. 12 S.
Stegner, Johannes; Gropp, Sebastian; Podoskin, Dmitry; Stehr, Uwe; Hoffmann, Martin; Hein, Matthias;
An analytical temperature-dependent design model for contour-mode MEMS resonators and oscillators verified by measurements. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 7, 2159, insges. 21 S.
Sachs, Jürgen; Ley, Sebastian; Just, Thomas; Chamaani, Somayyeh; Helbig, Marko;
Differential ultra-wideband microwave imaging: principle application challenges. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 7, 2136, insges. 32 S.
Wittich, Hans Christian; Seeland, Marco; Wäldchen, Jana; Rzanny, Michael Carsten; Mäder, Patrick;
Recommending plant taxa for supporting on-site species identification. - In: BMC bioinformatics, ISSN 1471-2105, Bd. 19 (2018), (30. Mai), Article 190, insges. 17 S.
Pandey, Ambrish; Scheel, Janet D.; Schumacher, Jörg;
Turbulent superstructures in Rayleigh-Bénard convection. - In: Nature Communications, ISSN 2041-1723, Bd. 9 (2018), 2118, insges. 11 S.
Singh, Sukhdeep; Mai, Patrick; Borowiec, Justyna; Zhang, Yixin; Lei, Yong; Schober, Andreas;
Donor-acceptor Stenhouse adduct-grafted polycarbonate surfaces: selectivity of the reaction for secondary amine on surface. - In: Royal Society Open Science, ISSN 2054-5703, Bd. 5 (2018), 7, 180207, insges. 7 S.
Wunder, Sophia; Hunold, Alexander; Fiedler, Patrique; Schlegelmilch, Falk; Schellhorn, Klaus; Haueisen, Jens;
Novel bifunctional cap for simultaneous electroencephalography and transcranial electrical stimulation. - In: Scientific reports, ISSN 2045-2322, Bd. 8 (2018), 7259, insges. 11 S.
Silge, Martin; Sattel, Thomas;
Design of contactlessly powered and piezoelectrically actuated tools for non-resonant vibration assisted milling. - In: Actuators, ISSN 2076-0825, Bd. 7 (2018), 2, 19, insges. 17 S.
Bartsch, Heike; Baca, Martin; Fernekorn, Uta; Müller, Jens; Schober, Andreas; Witte, Hartmut;
Functionalized thick film impedance sensors for use in in vitro cell culture. - In: Biosensors, ISSN 2079-6374, Bd. 8 (2018), 2, 37, insges. 9 S.
Wang, Dong; Schaaf, Peter;
Plasmonic nanosponges. - In: Advances in Physics: X, ISSN 2374-6149, Bd. 3 (2018), 1, Article: 1456361, insges. 19 S.

Gold nanosponges, or nanoporous gold nanoparticles, possess a percolated nanoporous structure over the entire nanoparticles. The optical and plasmonic properties of gold nanosponges and its related hybrid nanosponges are very fascinating due to the unique structural feature, and are controllable and tuneable in a large scope by changing the structural parameters like pore/ligament size, porosity, particle size, particles form, and hybrid structure. The nanosponges show the strong polarization dependence and multiple resonances behavior. Besides, the nanosponges exhibit a significantly higher local field enhancement than the solid nanoparticles. Strong nonlinear optical properties are confirmed by their high-order photoemission behavior, whereby long-lived plasmon modes are also clearly observed. All this is very important and relevant for the applications in enhanced Raman scattering, fluorescence manipulation, sensing, and nonlinear photonics.
Michaels, Anne; Grüning, Michael;
The impact of corporate identity on corporate social responsibility disclosure. - In: International journal of corporate social responsibility, ISSN 2366-0074, Bd. 3 (2018), 3, S. 1-13

Corporate social responsibility (CSR) is of increasing importance for the long-term success of corporations. Extending existing literature this paper explores corporate identity as important determinant for CSR disclosure. The relationship was examined based on 498 German companies that provided English language CSR reports and responded to a company survey measuring CSR-oriented corporate identity. CSR disclosure has been analyzed with an automated content analysis technique using artificial intelligence. Results indicate that value chain and future-oriented dimensions, which were more pronounced in mature CSR concepts, foster CSR disclosure, while introversive corporate identity dimensions that were strong in low level CSR concepts hinder the release of CSR information. The paper shows that a tradition of social responsibility and values results into a low perceived need for legitimacy and outwards communication. The findings support the view that that a combination of voluntary disclosure theory and legitimacy theory is necessary to explain the drivers and constraints of CSR disclosure.
Schreiber, Viktor; Ivanov, Valentin; Augsburg, Klaus; Noack, Matti; Shyrokau, Barys; Sandu, Corina; Schalk Els, Pieter;
Shared and distributed X-in-the-Loop tests for automotive systems: feasibility study. - In: IEEE access, ISSN 2169-3536, Bd. 6 (2018), S. 4017-4026
Ricciardi, Vincenzo; Augsburg, Klaus; Gramstat, Sebastian; Schreiber, Viktor; Ivanov, Valentin;
Survey on modelling and techniques for friction estimation in automotive brakes. - In: Applied Sciences, ISSN 2076-3417, Bd. 7 (2017), 9, p873, insges. 23 S.
Henke, Karsten; Fäth, Tobias; Hutschenreuter, René; Wuttke, Heinz-Dietrich;
Gift - an integrated development and training system for finite state machine based approaches. - In: International journal of online engineering, ISSN 1861-2121, Bd. 13 (2017), 8, S. 147-162
Pöschl, Sandra;
Virtual reality training for public speaking - a QUEST-VR framework validation. - In: Frontiers in ICT, ISSN 2297-198X, Bd. 4 (2017), Article 13 (19. Jun.), insges. 13 S.
Néel, Nicolas; Kröger, Jörg;
Template effect of the graphene Moiré lattice on phthalocyanine assembly. - In: Molecules, ISSN 1420-3049, Volume 22 (2017), issue 5, 731, Seite 1-9
Mohagheghi, Erfan; Gabash, Aouss; Li, Pu;
A framework for real-time optimal power flow under wind energy penetration. - In: Energies, ISSN 1996-1073, Bd. 10 (2017), 4, 535, insges. 28 S.
Ejaz, Waqas; Bräuer, Marco; Wolling, Jens;
Subjective evaluation of media content as a moderator of media effects on European identity: mere exposure and the hostile media phenomenon. - In: Media and communication, ISSN 2183-2439, Bd. 5 (2017), 2, S. 41-52

This paper posits that the concept of European identity is an important indicator of the legitimacy of the European Union (EU). It further assumes that the exposure to EU related media content can influence the feeling of European identity. In order to verify this assumption, we combined the mere-exposure-theory and the hostile media phenomenon. We assume that these theoretical concepts could help to understand the influence of media on peoples levels of attachment to the EU. Regression analyses are performed on secondary data that were collected in a Eurobarometer survey in 2013. Our findings revealed that media exposure affected the respondents' identification with Europe, as well as the modifications of this effect based on their assessments of EU media coverage. The results of the current study not only validate assumptions about the mere-exposure effects on identity but also confirm the theoretical assumption that perceived hostility reduces such effects, whereas exposure to information that is perceived as neutral promotes the effects of media exposure on the feeling of European identity.
Linß, Sebastian; Schorr, Philipp; Zentner, Lena;
General design equations for the rotational stiffness, maximal angular deflection and rotational precision of various notch flexure hinges. - In: Mechanical sciences, ISSN 2191-916X, Bd. 8 (2017), 1, S. 29-49

Notch flexure hinges are often used as revolute joints in high-precise compliant mechanisms, but their contour-dependent deformation and motion behaviour is currently difficult to predict. This paper presents general design equations for the calculation of the rotational stiffness, maximal angular elastic deflection and rotational precision of various notch flexure hinges in dependence of the geometric hinge parameters. The novel equations are obtained on the basis of a non-linear analytical model for a moment and a transverse force loaded beam with a variable contour height. Four flexure hinge contours are investigated, the semi-circular, the corner-filleted, the elliptical, and the recently introduced bi-quadratic polynomial contour. Depending on the contour, the error of the calculated results is in the range of less than 2 % to less than 16 % for the suggested parameter range compared with the analytical solution. Finite elements method (FEM) and experimental results correlate well with the predictions based on the comparatively simple and concise design equations.
Seeland, Marco; Rzanny, Michael Carsten; Alaqraa, Nedal; Wäldchen, Jana; Mäder, Patrick;
Plant species classification using flower images - a comparative study of local feature representations. - In: PLOS ONE, ISSN 1932-6203, Bd. 12 (2017), 2, e0170629, insges. 29 S.
Dutz, Silvio; Hayden, Mike E.; Häfeli, Urs O.;
Fractionation of magnetic microspheres in a microfluidic spiral: interplay between magnetic and hydrodynamic forces. - In: PLOS ONE, ISSN 1932-6203, Bd. 12 (2017), 1, e0169919, insges. 24 S.
Aksjonov, Andrei; Augsburg, Klaus; Vodovozov, Valerij;
Design and simulation of the robust ABS and ESP fuzzy logic controller on the complex braking maneuvers. - In: Applied Sciences, ISSN 2076-3417, Bd. 6 (2016), 12, 382, insges. 18 S.
Schricker, Klaus; Stambke, Martin; Bergmann, Jean Pierre; Bräutigam, Kevin;
Laser-based joining of thermoplastics to metals: influence of varied ambient conditions on joint performance and microstructure. - In: International journal of polymer science, ISSN 1687-9430, (2016), Article ID 5301081, insges. 9 S.

Laser-based joining of thermoplastics to metals shows a great potential for functional design especially in terms of lightweight constructions. In the joining process, the joining speed and the energy per unit length, respectively, show an influence on time-temperature profiles measured in the joining zone. The time-temperature profile affects the joining zone and consequently the joint behavior in mechanical testing. In the current investigation, the joining zone was characterized by the melting layer. Moreover, the mechanical properties of the joint by tensile shear testing and the fracture mode were investigated. Based on the results obtained, three sets of joining speeds/energies per unit length with different mechanical behaviors were selected for further investigations under varied ambient conditions. Thereby, the influence of outdoor weathering as well as aging above the glass transition temperature of the plastic part on the joints performance was compared with the nonaged joints.
Hotz, Thomas; Kelma, Florian; Wieditz, Johannes;
Non-asymptotic confidence sets for circular means. - In: Entropy, ISSN 1099-4300, Bd. 18 (2016), 10, 375, S. 1-13
Salchow, Christina; Strohmeier, Daniel; Klee, Sascha; Jannek, Dunja; Schiecke, Karin; Witte, Herbert; Nehorai, Arye; Haueisen, Jens;
Rod driven frequency entrainment and resonance phenomena. - In: Frontiers in human neuroscience, ISSN 1662-5161, Bd. 10 (2016), 413, insges. 12 S.
Mansoor, Arfan; Streitferdt, Detlef; Hanif, Muhammad Kashif;
Goal model integration for tailoring product line development processes. - In: International Journal of Advanced Computer Science and Applications, ISSN 2156-5570, Bd. 7 (2016), 7, S. 618-623
Klemm, Matthias; Blum, Johannes; Link, Dietmar; Hammer, Martin; Haueisen, Jens; Schweitzer, Dietrich;
Combination of confocal principle and aperture stop separation improves suppression of crystalline lens fluorescence in an eye model. - In: Biomedical optics express, ISSN 2156-7085, Bd. 7 (2016), 9, S. 3198-3210
Lau, Stephan; Petkovi´c, Bojana; Haueisen, Jens;
Optimal magnetic sensor vests for cardiac source imaging. - In: Sensors, ISSN 1424-8220, Bd. 16 (2016), 6, 754, insges. 17 S.
Lau, Stephan; Güllmar, Daniel; Flemming, Lars; Grayden, David B.; Cook, Mark J.; Wolters, Carsten H.; Haueisen, Jens;
Skull defects in finite element head models for source reconstruction from magnetoencephalography signals. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 10 (2016), 141, S. 1-15
Herz, Andreas; Franz, Anna; Theska, Felix; Hentschel, Martin; Kups, Thomas; Wang, Dong; Schaaf, Peter;
Solid-state dewetting of single- and bilayer Au-W thin films: unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution. - In: AIP Advances, ISSN 2158-3226, Bd. 6 (2016), 3, 035109, insges. 10 S.
Füßl, Franz Felix; Streitferdt, Detlef; Shang, Weijia; Triebel, Anne;
Introducing a method for modeling knowledge bases in expert systems using the example of large software development projects. - In: International Journal of Advanced Computer Science and Applications, ISSN 2156-5570, Bd. 6.2015, 12, Paper 1, S. 1-7

Goal of this paper is to develop a meta-model, which provides the basis for developing highly scalable artificial intelligence systems that should be able to make autonomously decisions based on different dynamic and specific influences. An artificial neural network builds the entry point for developing a multi-layered human readable model that serves as knowledge base and can be used for further investigations in deductive and inductive reasoning. A graph-theoretical consideration gives a detailed view into the model structure. In addition to it the model is introduced using the example of large software development projects. The integration of Constraints and Deductive Reasoning Element Pruning are illustrated, which are required for executing deductive reasoning efficiently.
Li, Pu; Vu, Quoc Dong
A simple method for identifying parameter correlations in partially observed linear dynamic models. - In: BMC systems biology, ISSN 1752-0509, Bd. 9.2015, 92 (14. Dez.), insges. 14 S.
Füßl, Franz Felix; Streitferdt, Detlef; Triebel, Anne
Modeling knowledge bases for automated decision making systems - a literature review. - In: International Journal of Advanced Computer Science and Applications, ISSN 2156-5570, Bd. 6 (2015), 9, S. 185-189
Ivanov, Valentin; Savitski, Dzmitry;
Systematization of integrated motion control of ground vehicles. - In: IEEE access, ISSN 2169-3536, Bd. 3 (2015), S. 2080-2099
Rothenberger, Liane; Müller, Kathrin;
Kategorisierung der von der Europäischen Union aufgelisteten terroristischen Gruppen gemäß ihrer Motive :
Categorizing terrorist entities listed by the European Union, according to terrorist groups' underlying motives. - In: Conflict & communication online, ISSN 1618-0747, Bd. 14 (2015), 2, S. 1-14

States and international organizations have compiled lists of a great variety of terrorist groups. The current European Union list includes 44 entities. This study analyzes the underlying motives of the terrorist organizations named in this list. In order to understand the groups' motivations and consequently be able to advise on methods of countering them with communication strategies, we employ a three-item typology provided by Waldmann (2001). The results show that only five of the 44 groups were religiously motivated to commit terrorism. Most of the groups (n=20) had nationalist-separatist motives, and 19 groups displayed social-revolutionary motives. Based on the respective motives, differing counter-terrorism strategies are proposed, e.g., developing rhetorical counter-narratives that address and reduce the groups' motivational and identity-generating characteristics.
Mansoor, Arfan; Streitferdt, Detlef; Füßl, Franz-Felix
Alternatives selection using GORE based on fuzzy numbers and TOPSIS. - In: Journal of software engineering and applications, ISSN 1945-3124, Bd. 8 (2015), 7, S. 346-359
Mansoor, Arfan; Streitferdt, Detlef; Füßl, Franz-Felix
Fuzzy based evaluation of software quality using quality models and goal models. - In: International Journal of Advanced Computer Science and Applications, ISSN 2156-5570, Bd. 6 (2015), 9, S. 265-273
Klemm, Matthias; Schweitzer, Dietrich; Peters, Sven; Sauer, Lydia; Hammer, Martin; Haueisen, Jens;
FLIMX: a software package to determine and analyze the fluorescence lifetime in time-resolved fluorescence data from the human eye. - In: PLOS ONE, ISSN 1932-6203, Bd. 10 (2015), 7, e0131640, insges. 28 S.
Wuttke, Heinz-Dietrich; Hamann, Marcus; Henke, Karsten;
Integration of remote and virtual laboratories in the educational process. - In: International journal of online engineering, ISSN 1861-2121, Bd. 11 (2015), 3, S. 62-67
This article is an extended and modified version of a paper presented at the International Conference on Remote Engineering & Virtual Instrumentation (REV2015), held in Bangkok, Thailand, 25 - 28 February 2015.
Hager, Markus; Seitz, Jochen; Waas, Thomas;
Literature survey on recent progress in inter-vehicle communication simulations. - In: Journal of Transportation Technologies, ISSN 2160-0481, Bd. 5 (2015), 3, S. 159-168
Weidner, Andreas; Gräfe, Christine; Lühe, Moritz; Remmer, Hilke; Clement, Joachim H.; Eberbeck, Dietmar; Ludwig, Frank; Müller, Robert; Schacher, Felix H.; Dutz, Silvio
Preparation of core-shell hybrid materials by producing a protein corona around magnetic nanoparticles. - In: Nanoscale research letters, ISSN 1556-276X, Bd. 10.2015, 1, Article 282, insges. 11 S.
Graichen, Uwe; Eichardt, Roland; Fiedler, Patrique; Strohmeier, Daniel; Zanow, Frank; Haueisen, Jens;
SPHARA - a generalized spatial Fourier analysis for multi-sensor systems with non-uniformly arranged sensors: application to EEG. - In: PLOS ONE, ISSN 1932-6203, Bd. 10 (2015), 4, e0121741, insges. 22 S.
Lauer, Kevin; Möller, Christian; Schulze, Dirk; Ahrens, Carsten
Identification of photoluminescence P line in indium doped silicon as In Si -Si i defect. - In: AIP Advances, ISSN 2158-3226, Bd. 5 (2015), 1, 017101, insges. 11 S.