This work provides a comprehensive review of the utilization of the Finite Element Analysis (FEA) in optimizing current density distribution within the Electrical Contact Interfaces (ECIs) of Electromagnetic Railguns (EMRs). Mastery over the current density distribution at ECIs is crucial for boosting the operational efficiency and longevity of EMRs. FEA is instrumental in identifying and rectifying issues stemming from non-uniform current density distributions, which can result in severe problems like local overheating, material degradation, increased friction wear, and a decline in launch capabilities. This review delineates the pivotal factors affecting current density at ECIs, including the Velocity Skin Effect (VSE), Current Skin Effect (CSE), Proximity Effect (PE), input current, contact pressure, and contact resistance. It then explores recent advancements on the FEA-driven optimizations of material and structures, which have markedly enhanced performance of EMRs. Challenges in applying FEA—such as the complexity of modeling multi-field interactions, computational demands, and ensuring simulation reliability—are also addressed, with recent innovations offering promising solutions. This work concludes by underlining the indispensable contribution of FEA to the progressive development of EMRs, spotlighting its vital role in spearheading future innovations through the fusion of cutting-edge methodologies and interdisciplinary collaborations.

The Taylor–Quinney coefficient (TQC) is a critical parameter quantifying the thermal conversion of plastic work during deformation in metallic crystals. This review provides a comprehensive summary of recent advances in TQC research, spanning experimental, theoretical, and computational perspectives. The fundamental principles of the TQC are introduced, emphasizing its thermodynamic background and dependence on microstructural features. Experimental studies demonstrate how the strain rate, temperature, and microstructure influence the TQC, with advanced techniques such as infrared thermography and high-speed imaging enabling precise measurements under dynamic conditions. Theoretical models, including internal variable frameworks and nonequilibrium thermodynamics, offer insights into the energy distribution mechanisms and provide predictive capabilities across diverse loading scenarios. Computational simulations, using methods like finite element analysis and molecular dynamics, reveal multiscale thermal conversion mechanisms and the role of dislocation motion and localized heat accumulation in governing TQC values. Challenges and opportunities for TQC research are highlighted, including the need for multiscale modeling, the exploration of complex stress states, and applications under extreme environments. Future directions should focus on integrating advanced experimental techniques and computational models to optimize material design and performance. This review aims to deepen the understanding of the TQC and its implications for energy dissipation and material reliability in high-performance applications.

Silicon photonic integration has gained great success in many application fields owing to the excellent optical device properties and complementary metal-oxide semiconductor (CMOS) compatibility. Realizing monolithic integration of III-V lasers and silicon photonic components on single silicon wafer is recognized as a long-standing obstacle for ultra-dense photonic integration, which can provide considerable economical, energy efficient and foundry-scalable on-chip light sources, that has not been reported yet. Here, we demonstrate embedded InAs/GaAs quantum dot (QD) lasers directly grown on trenched silicon-on-insulator (SOI) substrate, enabling monolithic integration with butt-coupled silicon waveguides. By utilizing the patterned grating structures inside pre-defined SOI trenches and unique epitaxial method via molecular beam epitaxy (MBE), high-performance embedded InAs QD lasers with out-coupled silicon waveguide are achieved on such template. By resolving the epitaxy and fabrication challenges in such monolithic integrated architecture, embedded III-V lasers on SOI with continuous-wave lasing up to 85 oC are obtained. The maximum output power of 6.8 mW can be measured from the end tip of the butt-coupled silicon waveguides, with estimated coupling efficiency of approximately -7.35 dB. The results presented here provide a scalable and low-cost epitaxial method for realization of on-chip light sources directly coupling to the silicon photonic components for future high-density photonic integration.

High speed and high efficiency photodetectors are the key components in optical transmission, optical sensing and optical processing systems. Except performance requirements, cost control is also an aspect that must be considered in the current technological development. Therefore, silicon-based high-speed and high-efficiency chip level photodetectors that can be monolithic integrated with very large-scale CMOS integrated circuits have become the focus of research. SOI structure provides performance improvement for silicon-based HPT. We demonstrate a SOI-based SiGe Heterojunction Phototransistor which has greater light absorption compared with Si-based HPT. The influence of SOI structure on absorption and collector current of SiGe heterojunction phototransistor (HPT) are simulated and analyzed in this paper. When the optical power is 10mw, the collector current in SOI-based HPT reported in this paper can reach 4.6mA with 5.83% of light absorption calculated, while the collector current in Si-based HPT is 3.35mA with 4.48% of light absorption calculated under 940nm wavelength. The peak responsivity with SOI structure exhibits 2.82A/W which is enhanced by 12.8% than that of Si-based HPT.