MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and ser...MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and serious volumetric change,largely hindering its practical applications.展开更多
The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of t...The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of the numerical simulation results of the pantograph-catenary interaction.Firstly,based on experimental data and the finite element method,models of a mass-point frame and reduced pan head were established,which can simulate the rolling and pitching motion characteristics of the dual-strip pan head.The correctness of the finite element numerical simulation of the pantograph-catenary system based on the model was verified through an industry standard and line tests.Then,the variation law of the standard deviation of the contact force(SDCF)in the speed range of 240-450 km/h was studied,and the mechanism of large fluctuation in SDCF was explained from the perspective of pantograph-catenary resonance.Finally,the influence of pan head degree of freedom and low-pass filtering frequency of the contact force time-domain signal on SDCF was studied,and the applicable speed level of the traditional three-mass model and 20 Hz filtering were provided.展开更多
挠曲电效应广泛应用于柔性传感、医疗复健、振动能量收集等领域,然而尚未有研究探讨挠曲形变量对挠曲电响应性能的影响。基于此,以MoS_(2)/PAN复合挠曲电传感薄膜为例,制备MoS_(2)/PAN弯曲传感器,采用X射线衍射仪和扫描电子显微镜对复...挠曲电效应广泛应用于柔性传感、医疗复健、振动能量收集等领域,然而尚未有研究探讨挠曲形变量对挠曲电响应性能的影响。基于此,以MoS_(2)/PAN复合挠曲电传感薄膜为例,制备MoS_(2)/PAN弯曲传感器,采用X射线衍射仪和扫描电子显微镜对复合挠曲电传感薄膜的晶体结构、微观形貌进行表征。在弯曲角度为0.1°、0.5°、1.5°、4°、7°、15°、30°和45°情况下,通过数字源表收集不同弯曲角度下MoS_(2)/PAN弯曲传感器的挠曲响应电压、电流和响应时间,分析挠曲形变量对挠曲电响应性能的影响规律,基于悬臂梁方法测试计算挠曲电系数。结果表明:MoS_(2)/PAN弯曲传感器挠曲电效应显著,挠曲电系数高达1.95 n C/m,当弯曲角度为7°时,MoS_(2)/PAN弯曲传感器获得最优的挠曲电响应,当弯曲角度小于7°时,挠曲电响应随弯曲角度的增大而增大,但是当弯曲角度大于7°时,挠曲电效应减弱。展开更多
针对现有分级多PAN太赫兹无线网络MAC(Medium Access Control)协议中存在的子网形成方案不合理以及私有CTA(Channel Time Allocation)与子网内实际负载不匹配等问题,提出了一种高效低时延的MAC层优化协议.该协议采用基于泛听的按需形成...针对现有分级多PAN太赫兹无线网络MAC(Medium Access Control)协议中存在的子网形成方案不合理以及私有CTA(Channel Time Allocation)与子网内实际负载不匹配等问题,提出了一种高效低时延的MAC层优化协议.该协议采用基于泛听的按需形成子网机制避免了子网分布不均匀以及因子网形成后没有节点加入而造成的私有CTA资源浪费的问题.在子网形成后,子微微网协调器(Piconet Coordinator,PNC)根据子网内实际负载情况自适应选择私有CTA时隙资源优化机制,让有数据传输需求的节点及时将数据发出.仿真结果表明,所提出的方案能有效地降低数据帧平均接入时延,提高吞吐量以及数据帧的传输成功率.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52102088 and 22075026)support from Teli Fellowship,Beijing Institute of Technology,and facility support from Analysis&Testing Center,and Experimental Center of Materials Sciences&Engineering at Beijing Institute of Technology.
文摘MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and serious volumetric change,largely hindering its practical applications.
基金supported by the Major Project of China Railway Co.,Ltd.(Grant No.K2021J004-A)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22020201)。
文摘The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of the numerical simulation results of the pantograph-catenary interaction.Firstly,based on experimental data and the finite element method,models of a mass-point frame and reduced pan head were established,which can simulate the rolling and pitching motion characteristics of the dual-strip pan head.The correctness of the finite element numerical simulation of the pantograph-catenary system based on the model was verified through an industry standard and line tests.Then,the variation law of the standard deviation of the contact force(SDCF)in the speed range of 240-450 km/h was studied,and the mechanism of large fluctuation in SDCF was explained from the perspective of pantograph-catenary resonance.Finally,the influence of pan head degree of freedom and low-pass filtering frequency of the contact force time-domain signal on SDCF was studied,and the applicable speed level of the traditional three-mass model and 20 Hz filtering were provided.
文摘挠曲电效应广泛应用于柔性传感、医疗复健、振动能量收集等领域,然而尚未有研究探讨挠曲形变量对挠曲电响应性能的影响。基于此,以MoS_(2)/PAN复合挠曲电传感薄膜为例,制备MoS_(2)/PAN弯曲传感器,采用X射线衍射仪和扫描电子显微镜对复合挠曲电传感薄膜的晶体结构、微观形貌进行表征。在弯曲角度为0.1°、0.5°、1.5°、4°、7°、15°、30°和45°情况下,通过数字源表收集不同弯曲角度下MoS_(2)/PAN弯曲传感器的挠曲响应电压、电流和响应时间,分析挠曲形变量对挠曲电响应性能的影响规律,基于悬臂梁方法测试计算挠曲电系数。结果表明:MoS_(2)/PAN弯曲传感器挠曲电效应显著,挠曲电系数高达1.95 n C/m,当弯曲角度为7°时,MoS_(2)/PAN弯曲传感器获得最优的挠曲电响应,当弯曲角度小于7°时,挠曲电响应随弯曲角度的增大而增大,但是当弯曲角度大于7°时,挠曲电效应减弱。
