Broadband DRA with uniform angular dependent delay for indoor localization. - In: IEEE access, ISSN 2169-3536, Bd. 12 (2024), S. 63644-63654
Estimating the Time Difference of Arrival (TDoA), is a simple yet reliable technique to accurately perform an indoor monostatic localization. To implement TDoA estimation, one approach is to utilize a broadband radar system equipped with multiple receiving antenna elements. To obtain the Time of Arrival (ToA) at each antenna element, the round-trip time is required. However, the round-trip time does not only consist of the propagation delay in free space but the propagation delay within the antenna as well. To perform the localization precisely, it is desired that an antenna element introduces a uniform delay in all directions. To this end, a compact rectangular dielectric resonator antenna is designed for the operating frequency of 6.5 GHz with a fractional bandwidth of 20%. Al2O3 with a dielectric constant of 9.8 is used for the substrate as well as the dielectric resonator. The antenna is designed to provide a high correlation between the input and the output pulses. To investigate the correlation, the antenna is excited with a modulated Gaussian pulse and the radiated pulses are studied. The antenna possesses an excellent behavior in terms of pulse preservation for the upper hemisphere. Therefore, when incoming pulses from the same distance but different directions impinge on the antenna, they reach the port of the antenna at a similar time. It is shown that this feature of the proposed antenna allows the utilization of TDoA estimation without the need for a calibration step. The characteristics of the antenna are verified by simulation and measurement.
https://doi.org/10.1109/ACCESS.2024.3395124
An experiment on the press coverage of child sexual abuse: can readers differentiate between good and bad reporting?. - In: Mass communication & society, ISSN 1532-7825, Bd. 0 (2024), 0, S. 1-23
News reporting on child sexual abuse (CSA) plays an important role in educating the public and fighting sexual violence, according to the public interest model of normative media theory. Bad reporting, however, is widespread and hinders a solution-oriented approach. Against this backdrop, the current study investigated which normative and subjective criteria are used by readers when they assess the quality of CSA newspaper reporting (RQ1). Furthermore, it was tested if readers can differentiate between good and bad CSA reporting quality (RQ2) and if their personal involvement in the topic - concerning victimization, exposure to CSA reporting, CSA knowledge - influences assessments of journalistic quality (RQ3). An experimental online study with a national quota sample of N = 2724 adults (18–65 years; Mage = 44.1; 52.5% women) from Germany was conducted in 2020. The study is preregistered and further materials are shared on osf.io. It turned out that readers mostly used the normative criteria to assess CSA reporting quality that are suggested by the academic literature (RQ1). Readers were able to differentiate between CSA reporting with high versus low journalistic quality (RQ2) - irrespective of their own CSA victimization (RQ3). Readers rated bad reporting as mediocre, though, indicating potential unawareness of certain quality issues.
https://doi.org/10.1080/15205436.2024.2335344
Research in brief: how prevalent is rough sex? Results from a national online sample of adults in Germany. - In: Perspectives on sexual and reproductive health, ISSN 1931-2393, Bd. 0 (2024), 0, S. 1-8
Background: Rough sex refers to consensual sexual activities that incorporate playful aggression, such as hair pulling, spanking, or choking. It is relevant in the context of sexual health as it can enhance sexual arousal, pleasure, and intimacy among consenting partners. However, it can also be associated with consent violations, discomfort, and injuries ranging from mild to severe or even fatal. The prevalence of rough sex in Germany is widely unknown. Our study aims to establish, for the first time, the overall age-related and gender-related prevalence rates of active and passive rough sex involvement among adults in Germany. Methods: A national online sample of 1101 adults from Germany, aged 18-69 years (50% men, 49% women, 1% gender-diverse individuals) gave informed consent and reported on their lifetime engagement in rough sex in active and passive roles. We recruited participants through a professional panel provider for a multi-themed sexual health survey. Data analysis was conducted using R, with 95% confidence intervals of prevalence rates computed to answer the research questions. Results: Lifetime prevalence of rough sex involvement was 29%. Adults below the age of 40 reported higher rates of involvement (up to 43%) than people over 40 (up to 26%). Men reported predominantly active role involvement and women reported primarily passive role involvement. Discussion: Results show that rough sex is common. Sexual health professionals, educators, and researchers should be prepared to guide current and aspiring practitioners of rough sex, helping them understand potential benefits, risks, and age- and gender-related differences.
https://doi.org/10.1111/psrh.12267
Dynamic characterization of Fiber Bragg Grating temperature sensors. - In: Experimental thermal and fluid science, Bd. 156 (2024), 111222, S. 1-10
To reliably characterize fast dynamic heat transfer mechanisms, fast-response temperature sensors are crucial, including knowledge about the temporal response. In this paper, the dynamic behavior of a Fiber Bragg Grating temperature sensor is investigated and compared to different types of fast-response thermocouples using two different experimental dynamic characterization methods. A temperature step is generated by either plunging the sensor into a fluid or exposing it to a fluid droplet at different temperatures. The step response is evaluated to determine the sensor response time. Calibration runs are performed for a silica-based 0.1 mm FBG sensor, as well as for 0.16 mm and 0.8 mm exposed tip and 0.25 mm sheathed tip type K thermocouples. Water, glycerin, oil and GaInSn were used to cover a broad range of applications regarding different thermal diffusivities and viscosities. The FBG sensor showed the shortest response times compared to the thermocouples, ranging from 60 ms in oil down to 3 ms in liquid metal, which is 20% up to 70% faster compared to a 0.25 mm sheathed tip type K thermocouple. Additional plunging calibration runs of the FBG sensor were performed in a ternary nitrate molten salt mixture (HITEC) to determine its overall and dynamic behavior in corrosive fluids at elevated temperatures. It turns out that the FBG sensor is not affected by the molten salt and shows similar response times to those measured in water. Regarding the characterization methods, both techniques show reproducible results, even though the droplet method is inapplicable for sensors with higher heat capacity or lower thermal conductivity than the calibration fluid. Furthermore, splashing effects for fluids with low viscosity reduce the reliability of the droplet method. The results also show that a dynamic characterization is indispensable for temperature measurements with high temporal resolution because the response time depends on the sensor size and the heat transfer coefficient between sensor and surrounding, which in turn depends on the sensor type, fluid properties and the flow parameters.
https://doi.org/10.1016/j.expthermflusci.2024.111222
Recent progress in transition metal based catalysts and mechanism analysis for alcohol electrooxidation reactions. - In: Green chemistry, ISSN 1463-9270, Bd. 0 (2024), 0, insges. 17 S.
In order to address energy and environmental challenges effectively, there is a need to promote renewable energy-driven electrochemical conversion technologies, particularly electrosynthesis. Electrosynthesis has the potential to convert abundant molecules into valuable chemicals and fuels. However, the widespread adoption of electrosynthesis is often hindered by the slow oxygen evolution reaction (OER). To overcome this limitation, we can employ the more efficient alcohol electrooxidation reaction (AOR), utilizing renewable biomass-derived alcohols as an alternative to OER for producing high-value chemicals. Consequently, the development of efficient AOR catalysts, in conjunction with cathodic reduction reactions (hydrogen evolution, oxygen, and nitrogen electroreduction, etc.), is crucial for sustainable and environmentally-friendly advancements. A thorough understanding of AOR mechanisms is essential for catalyst design and can be achieved through the utilization of in situ characterization techniques and density functional theory (DFT) calculations. This review summarizes recent progress in AOR catalysts, with a particular focus on the electrooxidation of monohydric alcohols, polyols, and associated studies on reaction mechanisms. Additionally, the review identifies key factors impeding AOR development and provides insights into future prospects.
https://doi.org/10.1039/D4GC00227J
Sustainable harnessing of waste polycarbonate for synthesizing activated furans to generate Stenhouse adducts on polymer surface. - In: Chemistry, ISSN 1861-471X, Bd. 0 (2024), 0, e202400369, insges. 21 S.
Plastics are versatile materials, offering lightweight, durable, and affordable solutions across various industries. However, their non-degradable nature poses challenges by end of their life. This study presented an innovative carbonyl extraction method to utilize waste poly(bisphenol A carbonate) (PC) as reaction precursor to synthesis of activated furan as precursor for photoswitchable Stenhouse adducts. This innovative chemical strategy not only generated N,N’-functionalized barbiturates but also provided an eco-friendly and cost-effective alternative to traditional synthesis methods. The method presented hereby not only promotes sustainability by repurposing waste polycarbonate as carbonyl equivalent under green conditions but also yielded reusable bisphenol A (BPA). Furthermore, the derived activated furans exhibited their functionality by forming colored donor-acceptor Stenhouse adducts (DASAs) on aminated polymer surfaces. This work demonstrated a transition from a linear plastics economy toward a circular one, highlighting the potential of plastic waste as a resource for creating materials with improved properties.
https://doi.org/10.1002/asia.202400369
Influence of increasing density of microstructures on the self-propagating reaction of Al/Ni reactive nanoscale multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, insges. 21 S.
Surface structuring methods are crucial in semiconductor manufacturing, as they enable the creation of intricate structures on the semiconductor surface, influencing the material’s electrical, mechanical, and chemical properties. This study employs one such structuring method known as reactive ion etching to create black Si structures on silicon substrates. After thermal oxidation, their influence on the reaction of Al/Ni nanoscale multilayers is. For this purpose, various densities of thermally oxidized black Si structures are investigated. It reveals distinct reactive behaviors without corresponding differences in energy release during differential scanning calorimetry measurements. Higher oxidized black Si structure densities result in elevated temperatures and faster reaction propagation, showing fewer defects and reduced layer connections in cross-sectional analyses. The properties of the reactive multilayers on high structure density show the same performance as a reaction on flat thermal SiO2, causing delamination when exceeding 23 structures per µm2. Conversely, lower structure density ensures attachment of reactive multilayers to the substrate due to an increased number of defects, acting as predetermined breaking points for the AlNi alloy. By establishing the adhesion between the reacted multilayer and the substrate, surface structuring could lead to a potential increase in bond strength when using reactive multilayers for bonding.
https://doi.org/10.1002/adem.202302225
Tailoring the reaction path: external crack initiation in reactive Al/Ni multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2302271, S. 1-6
The influence of intentionally externally induced cracks in reactive Al/Ni multilayer systems is investigated. These cracks affect the reaction dynamics and enable tailoring of the reaction path and the overall velocity of the reaction front. The influence of layer variations onto mechanical crack formation and resulting reaction behavior are investigated. High-speed camera imaging shows the meandering propagation of the reaction front along the crack paths. Therefore, the mechanical cracking process significantly changes the total velocity of the reaction front and thus offers a possibility to control the self-propagating high-temperature synthesis process. It is shown that the phase formation remains unaffected despite the applied strains and cracks. This favorable stability in phase formation ensures predictability and provides insight into the adaptation of RMS for precision applications in joints. The results expand the understanding of mechanical cracking as a tool to influence high-temperature synthesis in reactive multilayer coatings and provide an opportunity to expand the range of applications.
https://doi.org/10.1002/adem.202302271
Influence of metal surface structures on composite formation during polymer-metal-joining based on reactive Al/Ni multilayer foil. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, insges. 34 S.
Progressive developments in the field of lightweight construction and engineering demand continuous substitution of metals with suitable polymers. However, the combination of dissimilar materials results in a multitude of challenges based on different chemical and physical material properties. Reactive multilayer systems offer a promising joining method for flexible and low-distortion joining of dissimilar joining partners with an energy source introduced directly into the joining zone. Within this publication, hybrid lap joints between semi-crystalline polyamide 6 and surface-structured austenitic steel X5CrNi18-10 (EN 1.4301) were joined using reactive Al/Ni multilayer foils of the type Indium-NanoFoil®. Main objective is to examine possibilities of influencing crack initiation in the foil plane by variation of joining pressure and different metal surface structures with regard to geometry, density and orientation. Thus, the position of foil cracks is superimposed onto the metal structure and associated filling with molten plastic is improved. Consequently, characterisation of occurring crack positions as function of joining pressure and metal structure, analysis of the composite in terms of structural filling and joint strength as well as possible causes of crack initiation are evaluated.
https://doi.org/10.1002/adem.202302254
A novel method for preparation of Al-Ni reactive coatings by incorporation of Ni nanoparticles into an Al matrix fabricated by electrodeposition in AlCl3:1-eethyl-3-methylimidazolium chloride (1.5:1) ionic liquid containing Ni nanoparticles. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2302217, S. 1-17
Al/Ni reactive coatings are fabricated via electrochemical deposition (ECD) at different applied voltages for reactive bonding application. AlCl3:1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) (1.5:1) ionic liquid electrolyte is used as source of Al, whereas Ni is in the bath and incorporated into final coatings as nanoparticles (NPs). Scanning electron microscopy and Auger electron spectroscopy reveal a homogeneous Ni particle dispersion, as well as a high amount of particle incorporation into the Al matrix. A maximum of 37 wt% (22 at%) of Ni is detected via atomic absorption spectroscopy in the Al/Ni coating deposited at −0.1 V from an electrolyte containing 20 g L−1 of Ni NPs. Previous literature show that for bonding application an ideal concentration is around 50 at% of Ni and 50 at% Al. However, this is achieved using high vacuum, time-consuming processes, and costly techniques like evaporation and magnetron sputtering. The ECD used in this work represents a more cost-efficient approach which is not reported up to date for the aforementioned application. The reactivity of the coatings is confirmed by Differential scanning calorimetry. Herein, an exothermic reaction is detected upon the mixing of Al and Ni occurring at high temperatures.
https://doi.org/10.1002/adem.202302217