As we all know, the design of solar car focuses on lightweight in order to reduce the energy expenditure. However, the lightweight can induce large vibration, particularly in lower frequencies. The vibration not only ...As we all know, the design of solar car focuses on lightweight in order to reduce the energy expenditure. However, the lightweight can induce large vibration, particularly in lower frequencies. The vibration not only influences the riding comfort but also cause the fatigue breakage. So the dynamic performance of the solar car must also be taken into account. In this paper, the finite element model of a solar car frame is built, and the modal analysis is also performed. Afterwards,the frequency responses of the frame are analyzed under harmonic load. Finally, some modification is performed on this frame by structure optimization procedure.展开更多
Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of bette...Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically展开更多
Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding s...Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding spherical shell(MSSS)with minimal apertures,tailored to meet these requirements.By employing a combination of analytical solutions and finite element analysis(FEA),we achieved superior magnetic shielding while maintaining a compact form factor.The analytical solution for the shielding factor indicated that a four-layer permalloy sphere shell with optimized air gaps was necessary.A numerical analysis model of the MSSS was developed and validated using COMSOL software,confirming the suitability of the air gaps.The size,shape,and orientation of the openings in the perforated sphere shell were meticulously designed and optimized to minimize residual magnetism.The optimal structure was fabricated,resulting in triaxial shielding factors of 47619,52631,and 21739,meeting the anticipated requirements.A comparison of simulation results with experimental tests demonstrated the efficacy of the design methodology.This study has significant implications for ultrasensitive magnetic field detection devices requiring weak magnetic field environments,such as atomic gyroscopes,magnetometers,atomic interferometers,and atomic clocks.展开更多
文摘As we all know, the design of solar car focuses on lightweight in order to reduce the energy expenditure. However, the lightweight can induce large vibration, particularly in lower frequencies. The vibration not only influences the riding comfort but also cause the fatigue breakage. So the dynamic performance of the solar car must also be taken into account. In this paper, the finite element model of a solar car frame is built, and the modal analysis is also performed. Afterwards,the frequency responses of the frame are analyzed under harmonic load. Finally, some modification is performed on this frame by structure optimization procedure.
基金supported by The HongKong Polytechnic University Research Grants(No.1-BB81)grants from National Natural Science Foundation of China,Nos.10872078 and 10832012
文摘Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically
文摘为确定变参数桥梁最优内力,针对第十四届全国大学生结构设计竞赛赛题中的模型进行理论分析与优化,建立单目标线性优化设计数学模型和桥梁结构简化计算模型.采用穷举算法,结合Visual C++编程优化计算,其中包括桥梁主跨跨径的优化、加载点荷载值选择,进行静力分析、结构优化设计和实际模型试验.推导了数值计算公式,提出以弯曲应变能最小为目标的桥梁跨径、荷载加载位置等参数随机优化的方法,寻求在荷载作用下结构的竖向位移和内力的最小值,得到荷载布置方式,反算主跨跨径,利用有限元软件建模分析,并进行试验验证,得到布载方式1为最优布载,P 1~P 8值分别为40、50、120、130、60、70、80、90 N.
基金supported by Hefei National Laboratory,Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0300500 and 2021ZD0300503).
文摘Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding spherical shell(MSSS)with minimal apertures,tailored to meet these requirements.By employing a combination of analytical solutions and finite element analysis(FEA),we achieved superior magnetic shielding while maintaining a compact form factor.The analytical solution for the shielding factor indicated that a four-layer permalloy sphere shell with optimized air gaps was necessary.A numerical analysis model of the MSSS was developed and validated using COMSOL software,confirming the suitability of the air gaps.The size,shape,and orientation of the openings in the perforated sphere shell were meticulously designed and optimized to minimize residual magnetism.The optimal structure was fabricated,resulting in triaxial shielding factors of 47619,52631,and 21739,meeting the anticipated requirements.A comparison of simulation results with experimental tests demonstrated the efficacy of the design methodology.This study has significant implications for ultrasensitive magnetic field detection devices requiring weak magnetic field environments,such as atomic gyroscopes,magnetometers,atomic interferometers,and atomic clocks.
