An exploratory study on the use of threat intelligence sharing platforms in Germany, Austria and Switzerland. - In: ARES 23, (2023), 30, insges. 7 S.
Threat intelligence sharing is a promising solution to enhance knowledge and situational awareness of the rapidly growing number of emerging cyber threats. Accordingly, there are a variety of platforms on the security solutions market that enable the efficient and targeted exchange of threat intelligence across organisations. Unfortunately, very little is known so far about the dissemination and use of these platforms from the end-user perspective. To address this issue, we conducted an exploratory study on the use of threat intelligence sharing platforms in Germany, Austria and Switzerland. For this purpose, we surveyed 69 security and IT experts from large companies, federal authorities and public universities in autumn 2022. Our findings show, among other things, a growing interest in threat intelligence sharing platforms and their value to information security processes.
https://doi.org/10.1145/3600160.3600185
Heat management and tensile strength of 3 mm mixed and matched connections of butt joints of S355J2+N, S460MC and S700MC. - In: ce/papers, ISSN 2509-7075, Bd. 6 (2023), 3/4, S. 1476-1482
High-strength structural steels are beneficial in terms of the sustainability of constructions due to the possible reduction of weight and overall material needs. Nevertheless, high-strength steels have a smaller processing parameter range in regarding the specific heat input and resulting cooling rate. Especially the cooling time t8/5 characterizing the time span to cool down from 800 to 500 ˚C is an important indicator. Single layer butt-welded gas metal arc welding (GMAW) connections of 3 mm plates between normal strength (S355J2+N, S460MC) and high-strength steels (S700MC) as well as matched connections (S460MC, S700MC) are carried out. Hereby, the influence of the energy input, melting rate, joint preparation, filler metal (matching and undermatching) and backing methods are observed. Spatially resolved IR-thermal observation shows variations within the welds of up to 50 % in the cooling time t8/5 depending on those parameters. These fluctuations lead to significant changes of the microstructure within the melting and heat-affected zone. UCI hardness mappings show the softening and microstructural change within these zones. Those soft zones can be the region of failure for butt welded connections as shown by transverse tensile tests with spatially resolved optical strain measurements. The results obtained can be used to define more precise welding procedures of these types of connections and also are used to develop design rules for mixed connections made of normal strength and high-strength steel.
https://doi.org/10.1002/cepa.2265
Automatic camera selection, shot size, and video editing in theater multi-camera recordings. - In: IEEE access, ISSN 2169-3536, Bd. 11 (2023), S. 96673-96692
In a non-professional environment, multi-camera recordings of theater performances or other stage shows are difficult to realize, because amateurs are usually untrained in camera work and in using a vision mixing desk that mixes multiple cameras. This can be remedied by a production process with high-resolution cameras where recordings of image sections from long shots or medium-long shots are manually or automatically cropped in post-production. For this purpose, Gandhi et al. presented a single-camera system (referred to as Gandhi Recording System in the paper) that obtains close-ups from a high-resolution recording from the central perspective. The proposed system in this paper referred to as “Proposed Recording System” extends the method to four perspectives based on a Reference Recording System from professional TV theater recordings from the Ohnsorg Theater. Rules for camera selection, image cropping, and montage are derived from the Reference Recording System in this paper. For this purpose, body and pose recognition software is used and the stage action is reconstructed from the recordings into the stage set. Speakers are recognized by detecting lip movements and speaker changes are identified using audio diarization software. The Proposed Recording System proposed in this paper is practically instantiated on a school theater recording made by laymen using four 4K cameras. An automatic editing script is generated that outputs a montage of a scene. The principles can also be adapted for other recording situations with an audience, such as lectures, interviews, discussions, talk shows, gala events, award ceremonies, and the like. More than 70 % of test persons confirm in an online study the added value of the perspective diversity of four cameras of the Proposed Recording System versus the single-camera method of Gandhi et al.
https://doi.org/10.1109/ACCESS.2023.3311256
Comparison of fiber interferometric sensor with a commercial interferometer for a Kibble balance velocity calibration. - In: Measurement science and technology, ISSN 1361-6501, Bd. 34 (2023), 12, 125017, S. 1-10
This article presents a fiber interferometric sensor (FIS) for measuring the velocity amplitude of an oscillatory vibrating object, with a focus on velocity mode measurement in applications using the Kibble balance principle. The sensor uses the range-resolved interferometry method to measure the displacement of the moving object and employs a multi-harmonic sine-fit algorithm to estimate the displacement amplitude and frequency, thereby determining the velocity amplitude. This article provides a comprehensive explanation of the experimental setup and the measurement techniques employed, as well as a detailed analysis of the uncertainty budget, with the performance validation of the FIS benchmarked against a commercial interferometer within a Kibble balance setup. The velocity amplitude of a coil of the Kibble balance, oscillating with an approx. amplitude of 20 μm and a frequency of 0.25 Hz, was measured using the sensor and found to be 31.282 31 μm s^−1 with a relative deviation of −1.9 ppm compared to a commercial interferometer. The high performance of the FIS, especially with regard to non-linearity errors, and the small size of the measuring head enable universality of integration into a wide variety of measurement systems, also including the use as general-purpose vibration and displacement sensor.
https://doi.org/10.1088/1361-6501/acf2b7
Microwave angiography by ultra-wideband sounding: a preliminary investigation. - In: Diagnostics, ISSN 2075-4418, Bd. 13 (2023), 18, 2950, S. 1-17
Angiography is a very informative method for physicians such as cardiologists, neurologists and neuroscientists. The current modalities experience some shortages, e.g., ultrasound is very operator dependent. The computerized tomography (CT) and magnetic resonance (MR) angiography are very expensive and near infrared spectroscopy cannot capture the deep arteries. Microwave technology has the potential to address some of these issues while compromising between operator dependency, cost, speed, penetration depth and resolution. This paper studies the feasibility of microwave signals for monitoring of arteries. To this aim, a homogenous phantom mimicking body tissue is built. Four elastic tubes simulate arteries and a mechanical system creates pulsations in these arteries. A multiple input multiple output (MIMO) array of ultra-wideband (UWB) transmitters and receivers illuminates the phantom and captures the reflected signals over the desired observation time period. Since we are only interested in the imaging of dynamic parts, i.e., arteries, the static clutters can be suppressed easily by background subtraction method. To obtain a fast image of arteries, which are pulsating with the heartbeat rate, we calculate the Fourier transform of each channel of the MIMO system over the observation time and apply delay and sum (DAS) beamforming method on the heartbeat rate aligned spectral component. The results show that the lateral and longitudinal images and motion mode (M-mode) time series of different points of phantom have the potential to be used for diagnosis.
https://doi.org/10.3390/diagnostics13182950
Investigation on the influence of process parameters on the mechanical properties of extruded bio-based and biodegradable continuous fiber-reinforced thermoplastic sheets. - In: Polymers, ISSN 2073-4360, Bd. 15 (2023), 18, 3830, S. 1-14
The use of bio-based and biodegradable matrix materials in fiber-reinforced polymers (FRPs) is an approach to reduce the consumption of fossil resources and the amount of polymer waste. This study aims to assess the influence of the process parameters on the resulting mechanical properties of extruded bio-based and biodegradable continuous fiber-reinforced thermoplastics (CFRTPs) in the form of sheets. Therefore, the impregnation temperature during the production of PLA/flax fiber composites is varied between 220 ˚C and 280 ˚C, and the consolidation pressure, between 50 bar and 90 bar. A design of experiments approach is used. Fiber contents of 28.8% to 34.8% and void contents of 6.8% to 15.5% are determined for the composites by optical measurements. To assess the mechanical properties, tensile tests are performed. Using the evaluation software Minitab, a strong negative influence of the consolidation pressure on the tensile modulus and the tensile strength is observed. Increasing the pressure from 50 bar to 90 bar results in a reduction in the tensile modulus of 50.7% and a reduction in the tensile strength of 54.8%, respectively. It is assumed that this is due to fibers being damaged by the external force exerted onto the materials during the consolidation process in the calender. The influence of the impregnation temperature on the mechanical properties cannot be verified.
https://doi.org/10.3390/polym15183830
Ultrathin hematite-hercynite films for future unassisted solar water splitting. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. 8 (2023), 22, 2300655, S. 1-10
Photoelectrochemical (PEC) water splitting requires stable, efficient, and cost-effective photoelectrodes to enable future large-scale solar hydrogen production. Ultrathin hematite-hercynite photoanodes that meet all these criteria in an excellent way is presented here. Hematite-hercynite photoelectrodes are synthesized in a self-forming manner by thermal oxidation of iron-aluminum alloy films and characterized with regard to water splitting applications. Photoanodes fabricated from 17 wt.% Al at 493 ˚C for 8 h and 685 ˚C for 5 min exhibit, for instance, a photocurrent density of 1.24 and 1.53 mA cm−2 at 1.23 V versus RHE, respectively, as well as superior light absorption in the visible range of the solar spectrum. The PEC performance improvement in comparison to pure hematite thin film electrodes is first achieved by adjusting the aluminum concentration with an optimum range of 12-17 wt.% and second by optimizing the annealing conditions. The resulting photocurrent densities are about a factor of three higher than those obtained from electrodes synthesized from pure iron thin films using the same synthesis conditions. Finally, it is shown that ultrathin hematite-hercynite photoelectrodes enable even unassisted solar water splitting in a NaOH (1 m) electrolyte with a maximum solar-to-hydrogen conversion efficiency of 0.78%.
https://doi.org/10.1002/admt.202300655
Gel adsorbed redox mediators tempo as integrated solid-state cathode for ultra-long life quasi-solid-state Na-air battery. - In: Advanced energy materials, ISSN 1614-6840, Bd. 13 (2023), 42, 2302325, S. 1-10
In metal-air batteries, the integrated solid-state cathode is considered a promising design because it can solve the problem of high interfacial resistance of conventional solid-state cathodes. However, solid discharge products cannot be efficiently decomposed in an integrated solid-state cathode, resulting in batteries that are unable to operate for long periods of time. Herein, an integrated solid-state cathode (Gel-Tempo cathode) of sodium-air batteries (SABs) capable of promoting efficient decomposition of discharge product Na2O2 is designed. The Gel-Tempo cathode is synthesized by cationic-π interaction of redox mediator 2,2,6,6-tetramethyl-1-piperidinyloxy (Tempo) and ionic liquid with carbon nanotubes. The Gel-Tempo cathode serves multiple functions as a redox mediator, flame retardancy, and high stability to air. In quasi-solid-state SABs, the Gel-Tempo cathode reduces overpotential to 1.15 V and improves coulomb efficiency to 84.5% (at a limited discharge capacity of 3000 mAh g−1) compared to gel cathodes. Experiments and density functional theory calculations indicate that Tempo significantly reduces the Gibbs free energy in the decomposition reaction of Na2O2, and high Tempo content is more conducive to enhancing the decomposition kinetics of Na2O2 and hence resulting in an ultra-long cycle life (1746 h). This work is crucial to promote practical applications of SABs, providing guidelines for functionalization design of integrated solid-state cathodes for metal-air batteries.
https://doi.org/10.1002/aenm.202302325
Cooperative memory management for table and temporary data. - In: 1st Workshop on Simplicity in Management of Data, (2023), 2, insges. 5 S.
The traditional paradigm for managing memory in database management systems (DBMS) treats memory used for caching table data and memory for temporary data as separate entities. This leads to inefficient utilization of the available memory capacity for mixed workloads. With memory being a significant factor in the costs of operating a DBMS, utilizing memory as efficiently as possible is highly desirable. As an alternative to the traditional paradigm, we propose managing the entire available memory in a cooperative manner to achieve better memory utilization and consequently higher cost-effectiveness for DBMSs. Initial experimental evaluation of cooperative memory management using a prototype implementation shows promising results and leads to several interesting further research directions.
https://doi.org/10.1145/3596225.3596230
Understanding the formation of “false friends” (hidden lack of fusion defects) in laser beam welding by means of high-speed synchrotron X-ray imaging. - In: Welding in the world, ISSN 1878-6669, Bd. 67 (2023), 11, S. 2557-2570
This paper provides a fundamental understanding of “false friend” formation, i.e., hidden defects associated with lack of fusion, using an experimental setup that allowed an insight into the processing zone based on high-speed synchrotron X-ray imaging. The setup enabled the welding of a lap joint of AISI 304 high-alloy steel sheets (X5CrNi18-10/1.4301), with the ability to adjust different gap heights between top and bottom sheet (up to 0.20 mm) and to acquire high-speed X-ray images at 100 kHz simultaneously with the welding process. On this basis, a time-resolved description of the “false friend” formation can be provided by visualizing the interaction between keyhole and melt pool during laser welding and solidification processes within the gap area. The bridgeability of the gap was limited due to the gap height and insufficient melt supply leading to the solidification of the bridge. The distance between the solidified bridge and the keyhole increased with time, while the keyhole and melt pool dynamics initiated the formation of new melt bridges whose stability was defined by melt flow conditions, surface tension, and gap heights. The alternating formation and solidification of melt bridges resulted in entrapped areas of lacking fusion within the weld, i.e., “false friends.” Finally, based on the results of this study, a model concept is presented that concludes the main mechanisms of “false friend” formation.
https://doi.org/10.1007/s40194-023-01581-9