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 localization’s 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 work’s 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.
https://doi.org/10.1186/s13638-021-02001-6
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.
https://doi.org/10.1365/s40702-021-00723-1
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
https://doi.org/10.1007/s00103-021-03335-8
Study on friction in automotive shock absorbers, part 2: Validation of friction simulations via novel single friction point test rigs. - In: Vehicles, ISSN 2624-8921, Bd. 3 (2021), 2, S. 197-211
https://doi.org/10.3390/vehicles3020013
Study on friction in automotive shock absorbers, part 1: Friction simulation using a dynamic friction model in the contact zone of an FEM model. - In: Vehicles, ISSN 2624-8921, Bd. 3 (2021), 2, S. 212-232
https://doi.org/10.3390/vehicles3020014
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, S. 1-11
https://doi.org/10.3390/ijms22094977
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.
https://doi.org/10.1002/aenm.202100408
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.
https://doi.org/10.1016/j.matdes.2021.109790
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.
https://doi.org/10.1007/s41871-021-00100-y
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.
https://doi.org/10.3390/diagnostics11050818