NiFe/Cu多层膜的结构与层间耦合效应

用直流磁控溅射方法在玻璃基片上制备了[Ni_(80)Fe_(20)/Cu]_(20)多层膜,其中采用了靶表磁场强度不同的靶腔沉积铜层,利用X射线衍射和振动样品磁强计对Cu(100nm)/[Ni_(80)Fe_(20)(0.9nm)/Cu(tCu)]_(20)两个系列样品的结构和磁性进行了表征。靶表磁场较弱时沉积的多层膜具有良好的层间耦合振荡行为,而靶表磁场较强时制备的多层膜没有出现反铁磁耦合。依据上述事实,我们推测靶表磁场强度的不同会影响Ni Fe/Cu界面扩散,进而对多层膜样品的磁性产生影响。用靶表磁场较弱的靶腔沉积中间层铜能够有效减小界面互溶程度,改善镍铁与铜的成层质量。而靶表磁场较强的靶腔溅射出的铜原子具有较高能量,在界面处扩散并与镍铁层互溶,破坏了层状结构。     

Bi/Pt底层对Co/Ni多层膜反常霍尔效应的影响

采用直流磁控溅射法在玻璃基片上制备了一系列分别以Pt和Bi/Pt为底层的Co/Ni多层膜样品。通过研究Bi的厚度、周期层数、周期层中的Co和Ni的厚度以及退火温度对样品反常霍尔效应的影响,最终获得了霍尔效应最强、良好的霍尔曲线矩形度,同时具有良好的垂直各向异性的最佳样品Bi(1nm)/Pt(5nm)/[Co(0.3nm)Ni(0.5nm)]1/Co(0.3nm)/Pt(1nm)。实验表明,退火处理有利于增强反常霍尔效应。     

A novel simulation of AC magnetic contactor based on electromagnetic transients program

This paper proposes a new simulation approach for the AC magnetic contactor using the electromagnetic transients program (EMTP). The duality transformation technique is applied to convert a magnetic model into an electrical model. The great advantages of the proposed model are its capability of being directly simulated with other electrical components using EMTP and, therefore, its minimum level of complexity. To enhance the precision of the proposed model, the saturation of magnetic core and the fringing flux effects are taken into account. The performance and accuracy of the proposed model are verified by comparing them with those from finite element method (FEM) simulations and experiments. The results confirm that the proposed model has very good performance and the technique can be further applied to other magnetic components. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

电力物联网边缘计算终端业务时序逻辑与计算负荷建模方法

文中提出了一种边缘计算终端业务的时序逻辑与计算负荷建模方法.首先,提出了业务的时序逻辑图和边缘计算终端架构,构建了业务的计算负荷模型.然后,采用提出的计算负荷曲线生成算法获得业务的计算负荷时序曲线.最后,基于所生成的曲线对终端的计算资源进行配置,并分析了时序逻辑和终端架构对计算资源配置的影响.仿真结果表明,所提出方法可...     

配电物联网云边协同系统计算资源双目标优化配置方法

云边协同系统能够支持计算资源弹性扩展,适应配电物联网技术的需求。针对云边协同系统的计算资源配置问题,刻画了云边协同系统的计算资源,建立了计算业务模型,提出了批量计算业务的业务超时系数以对系统效果进行定量评价。基于上述模型,以最小化云边协同系统开销和最小化业务超时系数为目标,建立了考虑云边互动的计算资源优化配置双目标规划模型,并采用改进差分进化算法得到帕累托前沿。基于仿真算例讨论了不同双目标处理方法、通信质量、并发业务规模等对所提计算资源配置方法的影响。     

物联网背景下应用于光伏发电的边缘计算设备关键技术研究及应用

随着大数据、云计算、人工智能、5G等技术的快速发展,万物互联时代加速到来,网络边缘设备的数量和数据量都呈现快速增长态势.在此趋势下,边缘计算因具有靠近数据源、实时性好、时延短、响应快等特征,成为物联网发展的核心技术之一.基于此,介绍了边缘计算的基本概念及体系架构,探讨了边缘计算设备的关键技术;深入分析了边缘计算设备在光...     

Pr层厚度对纳米级Fe/Pr/Cu多层膜巨磁阻的影响

采用直流磁控溅射法制备Fe/Pr/Cu系列多层膜,在超高真空中进行热处理,测量了系列样品的结构和磁电阻。结果表明:退火温度为275℃的薄膜样品具有较好的层状结构和周期性。多层膜的层间耦合性质随Pr层的厚度增加而发生变化,巨磁电阻(GMR)效应随Pr层的厚度增加而减小。讨论了稀土Pr及Pr层的厚度对巨磁电阻效应的影响。     

Quantifying magnetic nanoparticles in non-steady flow by MRI

OBJECTIVE: This work compares the measured [Formula: see text] of magnetic nanoparticles to their corresponding theoretical values in both gel phantoms and dynamic water flows on the basis of the static dephasing theory. MATERIALS AND METHODS: The magnetic moment of a nanoparticle solution was measured by a magnetometer. The [Formula: see text] of the nanoparticle solution doped in a gel phantom was measured at both 1.5 and 4.7 T. A total of 12 non-steady state flow experiments with different nanoparticle concentrations were conducted. The [Formula: see text] at each time point was measured. RESULTS: The theoretical [Formula: see text] on the basis of the magnetization of nanoparticles measured by the magnetometer agree within 11% of MRI measurements in the gel phantom study, a significant improvement from previous work. In dynamic flow experiments, the total [Formula: see text] calculated from each experiment agrees within 15% of the theoretical [Formula: see text] for 10 of the 12 cases. The MRI phase values are also reasonably predicted by the theory. The diffusion effect does not seem to contribute significantly. CONCLUSIONS: Under certain situations with known [Formula: see text] , the static dephasing theory can be used to quantify the susceptibility or concentration of nanoparticles in either a static or dynamic flow environment at a given time point. This approach may be applied to in vivo studies.     

换流站交流场3/2接线中开关联锁跳闸逻辑设计与实现方法

为了解决换流站中开关联锁存在的问题,提出一种换流站中开关联锁逻辑设计与实现方法。利用中开关电流互感器二次电流作为启动量,结合两侧边开关在不同的运行方式,对中开关联锁逻辑进行智能化判断。考虑了与换流变或大组交流滤波器配串的交流线路在各种故障运行工况时的中开关动作逻辑,具备自适应运行方式的能力。仿真分析结果表明,该方法能适应大容量交直流系统各种运行工况,实现了对开关单跳、偷跳等涉及中开关联锁跳闸运行工况的智能化判断。     

电动汽车车用低压无刷直流电机控制系统设计

根据以无刷直流电机为驱动电机的电动车工作原理,基于MCU 79F9211芯片设计了电动车用低压无刷直流电机控制系统,并给出详细的系统硬件电路和软件设计方法。采用二相导通星形三相六状态的方法控制无刷直流电机,即易于实现又具有良好的性能,得到速度跟随性能良好的驱动系统。在MATLAB/Simulink环境下仿真得出合适的速度环与电流环调节参数,仿真结果验证该系统具有良好的性能。