半导体电学特性四探针测试技术的研究现状

四探针法是材料学及半导体行业电学表征较常用的方法,其原理简单,能消除接触电阻影响,具有较高的测试精度.由厚块原理和薄层原理推导出计算公式,并经厚度、边缘效应和测试温度的修正即可得到精确测量值.据测试结构不同,四探针法可分为直线形、方形、范德堡和改进四探针法,其中直线四探针法最为常用,方形四探针多用于微区电阻测量.本文综述了四探针测试技术的基本理论,包括四探针法的分类、原理和修正,并阐述了四探针测试技术在微观领域的发展.     

电能功率现场测量方法的计量性能

在功率测量原理的基础上,讨论了前端加源测值法和后端同步测值法的原理和特点,通过现场电能功率不同测量接入方式下的计量性能试验,并根据试验结果和不确定度的分析评定,指出两种方法的电能功率现场测量的计量差异,验证了两种现场功率测量方法计量性能一致性,对电能功率的现场测量工作具有参考价值。     

基于模态叠加法和直接刚度法的列车-轨道-桥梁耦合系统高效动力分析混合算法

为提高列车-轨道-桥梁耦合系统（Train-Track-Bridge Coupled System,TTBS）动力分析的计算效率,该文基于作者之前提出的TTBS动力分析混合模型,结合模态叠加法和直接刚度法,提出了一种改进的混合方法（Improved Hybrid Method,IHM）。该方法中,列车动力方程通过多刚体动力学方法建立;轨道结构动力方程通过直接刚度法建立以准确求解其高频局部振动响应,桥梁结构动力方程通过模态叠加法建立以降低其自由度数目。列车和轨道结构通过轮轨线性Hertzian接触关系耦合为列车-轨道耦合时变子系统,轨道与桥梁间通过轨-桥相互作用力的平衡迭代实现耦合。首先以朔黄重载铁路32 m简支梁桥现场试验数据验证了该文方法的正确性。然后,以CRH2型高速动车组通过万宁系杆拱桥为例,探究了桥梁振型数量对动力响应指标计算精度的影响规律,最后,对比三种不同的列车-轨道-桥梁耦合系统动力分析方法的计算结果及耗时,结果表明:同样的计算精度下,该文方法具有更高的计算效率。     

Blood flow imaging--A new real-time, 2-D flow imaging technique

This paper presents a new method for the visualization of two-dimensional (2-D) blood flow in ultrasound imaging systems called blood flow imaging (BFI). Conventional methods of color flow imaging (CFI) and power Doppler (PD) techniques are limited as the velocity component transversal to the ultrasound beam cannot be estimated from the received Doppler signal. The BFI relies on the preservation and display of the speckle pattern originating from the blood flow scatterer signal, and it provides qualitative information of the blood flow distribution and movement in any direction of the image. By displaying speckle pattern images acquired with a high frame rate in slow motion, the blood flow movement can be visually tracked from frame to frame. The BFI is easily combined with conventional CFI and PD methods, and the resulting display modes have been shown to have several advantages compared to CFI or PD methods alone. Two different display modes have been implemented: one combining BFI with conventional CFI, and one combining BFI with PD. Initial clinical trials have been performed to assess the clinical usefulness of BFI. The method especially has potential in vascular imaging, but it also shows potential in other clinical applications.     

TC4钛合金的超高周疲劳行为及其竞争失效模型构建

针对现有模型对TC4竞争失效预测的不准确性,建立了基于最大应力强度因子的竞争失效模型。在室温以及两种应力比下,针对TC4钛合金进行超高周疲劳试验,通过试验与最弱键竞争失效理论相结合的方法进行评估,研究其超高周疲劳性能。通过对试样断口形貌的观察,可将其失效模式分为如下两类:表面失效以及内部失效。对试样表面缺陷以及内部解理刻面尺寸进行测量,并评估其最大应力强度因子值。进一步通过正态分布得到最大应力强度因子的累计分布函数,基于两参数泊松分布建立了与最大应力强度因子有关的竞争失效模型。通过模型计算结果,可以得出在任一最大应力强度因子下试样发生各种失效模式的概率,且经分析对比,本文中TC4两种疲劳失效模式的失效概率评估结果与试验数据吻合较好,为分析TC4钛合金超高周疲劳状态下的疲劳失效模式提出了新的评估方法。     

Vibration measurement by the time-averaged electronic speckle pattern interferometry methods

Three different image-processing methods based on the time-averaged technique were compared by the electronic speckle pattern interferometry (ESPI) technique for vibration measurement. The three methods are the video-signal-addition method, the video-signal-subtraction method, and the amplitude-fluctuation method. Also, errors introduced by using the zero-order Bessel function directly into the analysis of the fringe pattern were investigated. The video-signal-addition method has been the most generally used ESPI technique for vibration measurement. However, without additional image and/or signal-processing procedures, the fringe pattern obtained directly by the video-signal-addition method is rather difficult to observe. The reason for poor visibility of the experimentally obtained fringe pattern with this method is explained. To increase the fringe pattern's visibility without additional image and/or signal processes, we tried two video-signal-subtraction methods. One of the two methods is the video-signal-subtraction method that has normally been used in the static applications. The other method, called the amplitude-fluctuation method, and its associated theory are reported here.     

Using a Single Toroidal Sample to Determine the Intrinsic Complex Permeability and Permittivity of Mn–Zn Ferrites

Analysis of the principle of the published lumped circuit methods for determination of the intrinsic complex permeability and permittivity of the Mn-Zn ferrites reveals that as long as the electric and the magnetic field distributions in the core(s) in two measurements are different, the two intrinsic values can be determined. Using this principle, we developed a set of general lumped circuit methods based on a toroidal Mn-Zn ferrite core as the measurement sample. We examined two possible different excitation modes: magnetic field excitation and electric field excitation. The two different excitation modes result in significantly different field distributions in the sample. Thus, high accuracy can be guaranteed in principle. For the magnetic field excitation, we present in this paper a general finite-difference method to solve the fields in the core and the impedance of the ferrite core inductor. To avoid the stray capacitance among the coils of the ferrite core winding inductor in the measurement, we made a set of short-ended coaxial test fixtures. We performed experiments to determine the intrinsic complex permeability and permittivity of a Mn-Zn ferrite core up to 10 MHz by using the two general methods and validated the measured intrinsic values experimentally.     

Stress measurement by X–ray diffraction using film techniques

For some X–ray stress measurement applications the photographic film methods may be preferred to diffractometer methods. The principles applied to the former are reviewed and the accuracy and sources of error are examined. The main procedures include the standard 'two exposure' method (including the use of the sin² method), and the use of a relationship depending on the asymmetry of rings at oblique incidence. A number of apparent errors in the literature are explained and resolved. The simplest formula for the second method takes the form =k.δR.
In the most favourable cases the accuracy of stress measurement is of the order of ±30 MN/m² or ±2 ton f/in². Larger errors arise for hardened surfaces with microstresses, and are likely to be larger for the second method. Both methods obviously give the most favourable results when sharp diffraction rings are obtained. However with proper care and appreciation of the factors considered, practically usefulresults are obtained under most circumstances. The treatment is illustrated by particular reference to surface residual stress measurement on steels.     

芯片表面形貌检测方法及系统研制

传统检测方法由于测量范围小、测量时间长,不能满足在线、在机和大幅面的检测需求,本文提出了一种白光扫描干涉和原子力显微测量相结合的芯片表面形貌测量方法。在分析了白光扫描干涉测量技术和原子力显微测量技术特点的基础上,构建了两种方法互补的测量方案：首先采用白光扫描干涉测量技术对芯片进行大范围快速扫描,再通过原子力显微测量技术对关键区域进行精细扫描检测。基于此进行了测量系统的硬件设计与集成,测试结果表明,该系统能够在毫米级检测范围内实现纳米级表面形貌的精确测量。     

纳米粒子粒径的测量研究

采用X射线衍射法(谢乐法)与透射电子显微镜法(TEM法)对纳米粒子粒径的测量进行了研究。结果表明,该两种方法都可用于纳米粒子粒径的的测量与表征,且两者的测量结果相当一致;纳米粒子实际平均粒径似应在两种方法测定结果之间。     

Looking into details of atom kinetics in intermetallics

Information on the atom jump processes during the establishment and destruction of long-range order can be gained from measurement of residual electrical resistivity (REST). By its nature this very sensitive method yields an integral signal, so theoretical efforts are mandatory to properly understand how the single atom jumps work together in generating it. As a valuable approach we report on Monte Carlo simulations of atom kinetics which process the individual jumps into macroscopic configurational changes. In order to create a more reliable quantitative basis for individual jump frequencies we propose ab initio calculations of defect energies and migration profiles, a method which has become increasingly accessible in recent years. When experimental investigation is enlightened by combining these two theoretical methods, we expect deep insight into the hierarchy of atomic movement during changes of the ordered state. First steps towards such an ideal program are discussed. An outlook is given how the theoretical methods described offer structural and kinetic information on various scales and in different systems.     

轴系扭矩测量方法与发展趋势

扭矩是反映轴系传动装置输出功率和评价其工作特性的主要技术指标,通过实时监测输出扭矩可为机械动力设备的可靠运行、故障诊断、安全维护提供有效保障,开展轴系扭矩测量方法研究具有重要意义。本文基于传递法的两大类扭矩测量原理,详细分析了当今研究较为广泛的几种应力(应变)检测型、扭转角检测型扭矩测量方法和传感器结构的工作原理、特点以及存在的问题。结合轴系传动装置自身的特点与发展,认为今后轴系扭矩测量方法应在应变片测量工艺改进、非接触式测量、特殊尺寸轴上测量、数据处理方法和可计量性设计几方面开展进一步研究。     

基于相关函数矩阵及卷积神经网络的结构健康监测研究

环境激励下利用时域振动响应构建的内积矩阵是结构健康监测中一种较好的结构特征参数。为了提升结构健康监测方法的识别准确率,构建内积矩阵时往往需要较多的振动响应测点,这将直接影响方法的工程实用性。该文基于时域振动响应的相关性分析理论,将内积矩阵扩展到了相关函数矩阵,实现从少量的振动响应测点中获取更多的结构健康特征信息,以降低结构健康监测方法对测点数量的需求。进一步结合卷积神经网络优异的数据特征提取能力,以相关函数矩阵为输入、结构健康状态为输出,提出了基于相关函数矩阵及卷积神经网络的结构健康监测方法。典型航空加筋壁板螺栓松动监测的实验研究结果表明,仅采用结构上任意2个测点的时域振动响应,该文方法针对螺栓松动位置的识别准确率可达99%以上。     

A linguistic risk prioritization approach for failure mode and effects analysis: A case study of medical product development

Failure mode and effects analysis (FMEA) is a widely used risk management technique for identifying the potential failures from a system, design, or process and determining the most serious ones for risk reduction. Nonetheless, the traditional FMEA method has been criticized for having many deficiencies. Further, in the real world, FMEA team members are usually bounded rationality, and thus, their psychological behaviors should be considered. In response, this study presents a novel risk priority model for FMEA by using interval two‐tuple linguistic variables and an integrated multicriteria decision‐making (MCDM) method. The interval two‐tuple linguistic variables are used to capture FMEA team members' diverse assessments on the risk of failure modes and the weights of risk factors. An integrated MCDM method based on regret theory and TODIM (an acronym in Portuguese for interactive MCDM) is developed to prioritize failure modes taking experts' psychological behaviors into account. Finally, an illustrative example regarding medical product development is included to verify the feasibility and effectiveness of the proposed FMEA. By comparing with other existing methods, the proposed linguistic FMEA approach is shown to be more advantageous in ranking failure modes under the uncertain and complex environment.     

误差综合测量的数字化码检仪

介绍了码检仪采用模拟量测量方式的原理、组成及存在的问题；提出了码检仪的数字化途径，原理和所有光栅检测参数的数字化测量，并对数字化测量进行了误差分析。通过对两种测量方式的比较，对数字化测量存在的问题提出了解决办法。     

运用WA-Delphi的钢铁企业经营效率评价方法

进行经营效率评价时充分考虑到定量分析和定性分析两个方面,把二者有机结合起来设置效率评价的相应指标,并在已有的绩效评价方法基础上,建立了一种新的采用权重分配的德尔菲法和数据包络分析相结合的评价方法。实证研究结果表明该模型对企业运行效率的评价是有效和可靠的。     

Precision ranger for measuring large mechanical components

We present a precision laser ranger system for the measurement of large manufactured components and structures. The system was developed based on a beat-wave interferometry principle. The light source of this system is a frequency-stabilized laser with a frequency stability of 1 x 10(-7) (in open air) or 10(-8) (in the laboratory). The laser operates in two longitudinal modes, and the two modes are generated in common resonator; therefore the two beams are naturally coaxial. The precision ranger system does not need a long guide or any heavy machinery. In this system an adaptive filter and a wavelet-transform program are used to improve the measurement accuracy. The system described here has a measuring range of 0-20 m and a measuring uncertainty of 30 microm/10 m.     

Power system energy analysis incorporating comprehensive load characteristics

The energy function method developed so far assumes that the active load is constant. However, most of the actual load is voltage dependent, which hinders the application of the energy analysis method to the actual power system. On the other hand, the fast development of measurement techniques, especially the wide area measurement systems (WAMS) applied widely in worldwide power system nowadays, presses for the on-line transient stability analysis tools based on the system measurements. The voltage-dependent load into the energy analysis of power system transient stability is discussed. The effect of the comprehensive load characteristics on the system energy is discussed and a WAMS-based energy indicator on the system stability status is proposed. The indicator is easy to be calculated and thus real-time in the operation centre is monitored. The proposed method does not rely on any specific load model, and various load characteristics on different buses can be considered. Simulations on two test systems verify the effectiveness of the proposed method.     

Solderability and its measurement

The ease with which molten solder wets and spreads on the appropriate metallic surfaces of electronic component assemblies during the manufacturing process is referred to broadly as the solderability of the component or printed circuit board. Two needs are evident: a traceable solderability measurement method giving reproducible data that predict process performance, and an agreed level of solderability which, for a given manufacturing process, will deliver an acceptably robust solder joint. This paper describes briefly present understanding of the mechanisms that govern solderability and the measurement methods most likely to prove acceptable to the electronics assembly industry     

Response analysis of Van der Pol oscillator subjected to harmonic and random excitations

The response of the Van der Pol oscillator subjected to combined harmonic and random excitations is investigated by a technique combining two excellent methods, namely the stochastic averaging method and the equivalent linearization method. The original equation is averaged by the stochastic averaging method at first. Then the resulting nonlinear averaged equations are linearized by the equivalent linearization method so that the equations obtained can be solved exactly by the technique of auxiliary function. The mean square response of the Van der Pol oscillator is computed algebraically and compared to the ones obtained by numerical simulation and by technique combining methods of stochastic averaging and equivalent non-linearization. The results show that the proposed technique gives a good prediction on mean square responses of the Van der Pol oscillator. In addition, the proposed technique can be applied to other nonlinear systems for it does not require any special conditions, and it can be improved by advanced optimization criteria of the equivalent linearization method.