Papers by Keyword: Resistance

Abstract: In this paper, the radiation resistance of GaN and SiC is compared. The effect of the irradiation temperature on the carrier removal rate in both semiconductors during proton irradiation is considered. It was found that in GaN, as well as in SiC, the rate of carrier removal decreases with increasing irradiation temperature. The dependence of the GaN sample resistance on the radiation dose was also calculated based on a model previously proposed to describe a similar dependence for SiC. Based on the experimental data obtained, it is concluded that the processes of radiation compensation in GaN and SiC are similar.

Abstract: In this work, we investigate the static electrical parameters of 1200 V 4H-SiC power diodes with various designs and architectures (Schottky, PiN, and JBS with hexagonal or stripes anode), fabricated on two types of 150 mm substrates (single crystal 4H-SiC reference and 3C-poly silicon carbide based substrates: SmartSiC^TM). I(V) measurements are carried out in both reverse and forward modes to assess the impact of designs and substrates. Non-destructive avalanche mode is reached with similar performance (leakage, V_AV) observed for both substrates (due to identical drift layers and device structures). All diode designs on SmartSiC^TM exhibit a larger current conduction and less resistance in the ohmic regime (compared to bulk), whatever the temperature (up to 200°C). Partitioning model is also proposed for evaluating the substrate contribution on the measured specific resistance and on the observed SmartSiC^TM gains.

Abstract: Graphene–ZnO composite thin film was synthesized using Hummer method and prepared using electrodeposition has good potential for supercapacitors applications. However, times of electrodeposition could influence the capacitive behaviour due to concentration of graphene layer. The cyclic-voltametric, CV and impedance spectroscopy, EIS showed significant data on these studies. Five samples with concentration of graphene from 1 mg/ml to 5 mg/ml was prepared, represent from 0.04, 0.08, 0.12, 0.16 and 0.20 g mass of graphene. Deposition time was selected to 20, 40 and 60 minutes at 5V of fixed deposition voltage. Despite cyclic voltammetry, these five sample also was measured on their conductivity. CV characterizations of GZ4-20 shows the best result in CV curve shape with complete charging discharging process at 2.88E-05 Fg^-1 for specific capacitance at 20 minutes. The EIS characterization of GZ5-40 shows series resistance at 523.220 Ω as the best result in EIS characterization for 40 minutes electrodeposition time. Deposition time of Graphene-Zinc Oxide at 40 minutes prove that the time can influence on electrocatalytic performance. However, it can be good candidate for various micro electrical of capacitor devices.

Abstract: Adhesive joints are essential in modern engineering, offering lightweight, durable and efficient solutions for bonding in industries such as aerospace, automotive, and renewable energy. However, their fatigue performance under cyclic loading remains a critical challenge, shaped by a complex interplay of geometrical, material, environmental, and loading factors. This review explores the mechanisms of fatigue failure, highlighting the importance of joint design, material optimization, and surface preparation in mitigating stress concentrations and enhancing durability. Advances in toughened adhesives, surface treatments, and environmental protection methods are highlighted, along with predictive models ranging from empirical S-N curves to advanced finite element simulations and probabilistic approaches. Despite significant progress, challenges remain in integrating these techniques for real-world applications, particularly under variable loading and harsh environmental conditions. Future research must focus on hybrid methodologies, adaptive materials, and standardized protocols to bridge the gap between laboratory insights and practical implementations. This comprehensive review provides a foundation for improving the fatigue performance of adhesive joints, ensuring their reliability and effectiveness in critical engineering systems.

Abstract: GaN power HEMTs enable the design of power electronic systems with highest efficiencies and reduced size. Despite strong advancements in device reliability, charge carrier trapping is still an important challenge. The applied methodology allows to characterize defects that cause the dynamic R_DS,on in GaN power devices at product level with flexibility in duty cycle, number of pulses and mission profile. A pronounced trapping is observed for lateral GaN-on-Si HEMTs with Schottky p-GaN gate structure at low drain bias and long off-state pulses (> 100 ms). The effect is investigated by fast determination of the on-state resistance R_DS,on under different trap capturing conditions: a) different drain bias b) off-state time and number of cycles c) variation of temperature. The trapping and detrapping effects are characterized and the activation energy is extracted from time constants. An elevated on-state resistance was present for up to 3 hours. The threshold voltage modification due to high drain bias does explain the significant R_DS,on increase.

Abstract: Ballistics is the science and dynamics of a moving projectile. This field helps to understand the accuracy of different projectiles, from bullets to rockets. Ballistics is based on physics, particularly Newtonian mechanics, and plays an important role in the defense industry, as well as space exploration, sports, and many other areas of life. The study of ballistics is broadly divided into four distinct segments: internal, transitional, external, and terminal ballistics. Each segment provides insight into a particular stage in the projectile's life.External ballistics plays an important role in the study of the movement process of the bullet during its movement, in understanding and optimizing the principle of operation of firearms, artillery and other ballistic systems. Understanding external ballistics is critical in firearms, artillery, archery, and even sports such as golf and baseball. In this article, we will delve into the ins and outs of external ballistics and explore the various factors that affect projectile range.

Abstract: The article presents the results of research focused on the behavior of composites with a matrix based on alkali-activated materials when exposed to extreme temperatures (up to 1200°C). The behavior of the material based on alkali-activated fly ash, blast furnace slag, metakaolin, their mutual combinations respectively was analyzed in detail. The effect of thermal exposure on the properties of the developed materials was assessed by a complex of physical, mechanical and chemical methods. A specific area of research was the examination of the rheological properties of the developed mixtures in the fresh state.

Abstract: The Cluster of Excellence “Centre for Tactile Internet with Human-in-the-Loop (CeTI)” deals with developments and inventions concerning smart devices used in many fields, e.g. industry 4.0, medicine and skill learning. These kind of applications require smart devices, sensors, actors and conductive structures. Textile structures address these applications by meeting requirements such of being flexible, adaptable and wearable. Within this paper, the development of a protective coating for electrically conductive (EC) yarns is captured. These EC yarns are nowadays often used for smart textile applications. One challenge in their application is the integration into textile structures. Often, the handling and use of EC yarns lead on the one hand to damages on the surface of the yarn and on the other hand to reduced electromechanically characteristics. This paper aims to characterize these EC yarns in regard to develop a suitable protective coating based on polypropylene (PP). To achieve this development, an extensive characterization of the EC yarns as well as the protective coating itself is important. The surface free energy (SFE), the topographical and the chemical characteristics are necessary for developing a suitable protective coating. However, the yarns are characterized before and after implementation into the textile structure and furthermore after the coating respectively with the developed finish.

Abstract: The article deals with the influence of crystallization additives on the life of self-compacting concrete (so-called SCC concrete), which are exposed to chemically aggressive environments. The focus is not only on the effect of the crystallization additive on the characteristics of the capillary-pore structure of SCC concrete, but especially long life durability of self-compacting concrete (two years expozition). The effect of individual types of aggressive environment is assessed on the basis of a set of physico-mechanical and physico-chemical analyzes.

Abstract: The article presents the physical-chemical bases and as result – the technological bases of concrete resistance to ultra-low cryogenic (up to-196 °C) technical (engineering) temperatures, which is applied to the reinforced concrete structures of engineering constructions such as storage tanks for liquefied gases (in particular, liquid nitrogen and oxygen with cryogenic temperatures), as well as the enclosing structures of blocks (units) for air separation for various inert gases. The above-mentioned physical and chemical bases of concrete resistance to the ultralow cryogenic technical temperatures are developed, using the results of the analysis of modern ideas (hypotheses and theories) about the mechanism of low negative temperatures exposure on structural lightweight aggregate concrete and normal weight concrete due to the characteristics of their macro-and microstructure. The resistance of structural lightweight aggregate concrete in comparison with equal-strength normal weight concrete to the cyclic exposure of cryogenic temperatures was performed by the authors based on the results of the relevant analytical and experimental investigations. The results of these investigations are considered in the article as a modern scientific basis for the development of the main provisions for the manufacturing technology of structural lightweight aggregate concrete and normal weight concrete with high durability (frost resistance and water resistance) in conditions of cyclic exposure to cryogenic temperatures. The results of changes in strength and deformative characteristics of concrete in the process of cyclic freezing and thawing are accepted as evaluation criteria of the resistance of concrete, manufactured using the above-mentioned technologies, to such temperature exposure.