高频变压器绕组涡流损耗等效因子分析

针对平面磁性元件,利用Dowell模型和有限元方法对绕组涡流损耗等效因子Δ进行研究。分别对单股、多股圆导线和其等截面积正方形导线进行仿真分析,得到当圆导线直径为2~6个集肤深度时,涡流损耗减小显著;当圆导线直径大于6个集肤深度时,涡流损耗趋于平稳。圆导线直径为2~6个集肤深度时,等效因子的值较为理想;圆导线直径大于6个集肤深度时,其值偏低。为了提高设计的精确性应尽量选择直径少于6个集肤深度的圆导线。     

2.5D转接板封装高频互连结构设计、分析与测试

An interposer test vehicle with TSVs(through-silicon vias) and two redistribute layers(RDLs) on the top side for 2.5D integration was fabricated and high-frequency interconnections were designed in the form of coplanar waveguide(CPW) and micro strip line(MSL) structures. The signal transmission structures were modeled and simulated in a 3D EM tool to estimate the S-parameters. The measurements were carried out using the vector network analyzer(VNA). The simulated results of the transmission lines on the surface of the interposer without TSVs showed good agreement with the simulated results, while the transmission structures with TSVs showed significant offset between simulation and test results. The parameters of the transmission structures were changed,and the results were also presented and discussed in this paper.     

AC/DC开关电源建模与仿真研究

文章对全桥型开关电源结构进行分析,对关键元器件的作用、参数计算方法进行阐述.在Multisim仿真软件中搭建整体电路模型,研究改变电路参数对于电路性能的影响,验证开关电源仿真的可行性.针对硬开关产生的开关损耗问题,建立ZVS-移相全桥变换器的简化模型,仿真研究开关管的软开关过程.     

未来航电系统FC互连的拓扑结构研究

简述了航空电子系统互连的发展和光纤通道技术的基本特点;介绍了FC的3种基本拓扑结构：点到点、仲裁环和交换网络;研究了未来航空电子系统互连的关键协议——光纤通道(FC)的拓扑结构。     

紧凑型节能荧光灯高频参数测试系统研制

本文介绍了一种紧凑型节能荧光灯的高频工作特性测试系统。该系统成本低、功能强、具有自动清零、采集并处理数据、输出结果的功能；实验证明它能快速、准确、自动地一次完成荧光灯所有高频工作参数的测量。     

An integral equation method for the evaluation of conductor anddielectric losses in high-frequency interconnects

An integral equation method is developed to solve for the complex propagation constant in multilayer planar structures with an arbitrary number of strip conductors on different levels. Both dielectric losses in the substrate layers and conductor losses in the strips and ground plane are considered. The Green's function included in the integral equation is derived by using a generalized impedance boundary formulation. The microstrip ohmic losses are evaluated by using an equivalent frequency-dependent impedance surface which is derived by solving for the fields inside the conductors. This impedance surface replaces the conducting strips and takes into account the thickness and skin effect of the strips at high frequencies. The effects of various parameters such as frequency, thickness of the lines, and substrate surface roughness on the complex propagation constant are investigated. Results are presented for single strips, coupled lines, and two-level interconnects. Good agreement with data available in the literature is shown     

传感器布置对水轮机振动特征参数影响研究

在水轮机故障诊断中,通常通过在水轮机轴周围布置传感器来获取其振动参数,但传感器的布置位置可能会影响到部分振动特征参数数值,因此研究传感器布置对水轮机振动特征参数的影响有着重要意义.本文拟从数学建模及仿真的角度研究传感器布置对水轮机振动特征参数的影响,以传统旋转误差三点检测方法为指导,建立三点、二点和四点法的主轴旋转数学模型,以扫描点处的相对误差值作为特征参数进行研究,通过对仿真结果的分析比较最终可得到最佳的传感器布置方法.     

基于动态相量法的PWM DC/DC变换器的建模与分析方法

文章从动态相量的概念以及基本性质出发,推导了动态相量法应用于PWM DC/DC变换器建模与分析的数学方法。首先介绍了纹波的计算方法,引入了选择模式分析法对PWM DC/DC变换器动态相量模型进行简化,建立了小信号模型,并以PWM BUCK/BOOST双向DC/DC变换器为例,用MATLAB软件建立了PWM DC/DC变换器的动态相量模型,将之与时域仿真模型进行了比较,验证了该方法的有效性。     

On the avalanche multiplication mechanism in SPICE simulations of high-frequency bipolar transistors with thin basewidths and low breakdown voltages

A very simple subcircuit model for SPICE simulation of bipolar transistors affected by the avalanche multiplication mechanism is presented. The currently available models for bipolar transistors in circuit simulators do not consider this effect, which can lead to serious simulation errors when high-frequency thin basewidths transistors with low and soft breakdown voltages are simulated. The simulated results predicted by SPICE with the proposed subcircuit are compared with the measured data obtained from several transistors with low and soft breakdown voltages and a good agreement is reported.     

Influence of pulsed DC current stress on electromigration results in AlCu interconnections; analysis of thermal and healing effects

Electromigration experiments have been performed on AlCu interconnect structures subjected to unipolar or bipolar current stresses. Activation energy values were similar between AC and DC stress suggesting that the same failure mechanisms occurred in both cases. From 100 Hz to 1 MHz, the results followed an average current model for which the sample is stressed by an efficient current density averaged over the period and Joule heating is taken into account with an original thermal model. The average current model was also verified for bipolar currents and provided very large increase of median time to failure when symmetric signals were considered. Asymmetric signals lead to unipolar electromigration behavior. At 1 Hz, the results tend toward an on time model for which matter diffusion occurred only during the application of the current.     

紧凑型荧光灯高频工作特性研究

利用自行研制的荧光灯高频工作参数测试系统，测试了几种紧凑型荧光灯的高频工作光电参数，阐明了高频电子镇流器的频率、波形对灯的光通、光效、功率因数等光电参数的影响情况，并找出了灯的最佳工作频率，为生产高质量的灯管和电子镇流器提供了理论依据。     

浅析喷嘴对精细线路蚀刻效果的影响

讲述喷嘴对蚀刻0.075mm/0.075mm等精细线路线宽、线距的影响,主要通过新、旧喷嘴的蚀刻效果对比,验证喷嘴对蚀刻效果产生的影响。     

An algorithm for the determination of eddy-current losses and temperatures in a conductor subjected to high-frequency magnetic-flux variations

An algorithm is presented for the determination of temperature at any time and at any interior point of a plane metallic body, given the surface heat flux. Alternatively, given the temperature at a specific point and time in a plane semi-infinite metallic body, with little or no assumed surface heat loss, the surface heat flux can be determined. The technique can be used to estimate open-circuit tooth ripple eddy-current losses in a smooth section of the laminated poles of synchronous machines. It is readily implemented on a programmable calculator.     

CMOS线驱动器输出信号压摆率控制的研究

线驱劝器的输出信号压摆率(slew rate)与信号在传输线上的反射(reflection)、电磁干扰(Electro-Magnetic Interference)密切相关，适当缓的压摆率对抑制信号在传输线上的反射和电磁干扰非常有效。设计了一种新的CMOS线驱劝器输出压摆率控制电路。采用华晶上华0．6μmCMOS工艺模型，对该电路进行了Hspice仿真。结果表明，该电路能很好地控制CMOS线驱劝器的输出压摆率，可获得几十ns到几μs的上升或下降时间。     

湍流谱中高频"泵浦"对激光大气传输影响的数值模拟研究

当湍流不稳定时,在折射率谱的高频端会出现特殊的能量注入而形成狭窄的高频"泵浦(bump)",结构.采用数值模拟的方法研究分析了该高频bump结构的性质及其对激光大气传输的影响.数值模拟结果表明:高频bump的存在使得光强起伏功率谱的高频端出现了尖峰结构并伴有次频成分;随着折射率谱中bump强度的增大,光强起伏功率谱的高频端渐渐偏离-8/3幂律而下降速度减慢;高频bump还使得光束发生扩展,光束有效半径随bump强度的增大而先增大后减小最后趋于一稳定值,光束有效半径随bump宽度的增大而增大,最大的光束有效半径可以达到不存在bump时光束有效半径的数倍.     

高频喷射呼吸机高浓度给氧引起兔肺泡损伤的组织学研究

使用高频喷射呼吸机经鼻腔给家兔供氧，氧浓度大于９０％。分别按６、１２、２４小时组给氧，处死动物，取肺进行组织学及超微结构观察、设对照组动物供氧含量为４０％，时间２４小时。结果表明对照组无病变；６小时组肺泡气－血屏障层中细胞膜发生损伤，且微饮泡消失；１２小时组肺泡扩张，肺泡壁断裂；２４小时组光镜可见肺水肿，电镜可见高电子密度复盖层在气－血屏障层之上。说明高浓度给氧的病变随时间延长而加重。     

不同传输环境下MIMO信道的空间相关性的研究

基于宏小区及微小区MIMO信道模型,比较了MIMO信道在两种传输环境中的空间相关特性,通过数值分析方法得到了两类信道空间相关性随发送端、接收端天线阵列的分布而变化的特征曲线,并分析比较了信道参数,即到达角的角度扩展,对空间相关性的影响。在此基础上,讨论了空间相关系数对系统功率有效性和频带有效性的影响,找到了在不同传输环境下,影响系统BER性能的空间相关系数的门限。     

Impact of DC components in transport current and external magnetic field on hysteresis losses in an HTS tape

The high-temperature superconductor (HTS) development is presently intensive, and one can expect that HTSs will be used in different electric devices in the future. In some of these devices, e.g., a magnetostrictive actuator, the conductor will be exposed to both ac and dc transport currents and external magnetic fields. One of the most important parameters in the design of electric devices is the power loss. It is, therefore, of importance to develop models that are able to predict the power loss in devices based on HTSs. In this paper, we present an experimental characterization of the hysteresis losses in an HTS tape exposed to ac or dc transport currents in combination with external magnetic fields. The experimental results are compared to some existing models based on the critical state model. The power loss was measured on a multifilamentary Bi-2223 tape at constant temperature (70 K) and frequency (50 Hz).     

强激光大气传输非线性热畸变效应的解析分析

高功率激光在大气中传输时产生的非线性热畸变效应对激光的传输形成严重的限制,使光束质量严重下降,到达靶面的光强远低于初始光强。文中分析了非线性热畸变形成的物理机制,从光波大气中传输的标量波动方程以及流体动力学方程组出发,对稳态和瞬态的各种非线性热畸变现象进行了分析,给出了非线性热畸变效应与激光参数的相关性,获得了较为满意的结果。     

Effects of Mg additions on the electromigration behavior of Al thin film conductors

Aluminum thin film conductors containing Mg alloying additions have been tested for electromigration failure by formation of electrically open circuits. The test conditions were either 2 × 10⁶ A/cm² or 4 × 10⁶ A/cm² for the current density, and either 175 or 225°C for the temperature. The median lifetimes were found to increase with increasing Mg concentrations up to the highest concentration tested, about 6%. With polycrystalline films the maximum increase in lifetime resulting from Mg additions corresponds to a factor of about 100, as compared to pure Al films. This is about equal to previously reported results obtained with Cu additions. The increase in lifetime has been shown to result from a decrease in the rate of grain boundary diffusion for the Al atoms. Magnesium atoms diffuse at approximately the same rate as Al atoms. Thus the mechanism of failure formation in Al films containing Mg is thought to be different than in Al-Cu films, where Cu atoms diffuse faster than Al atoms and failure ensues upon local Cu depletion.