热释电材料电性能自动测量系统的设计

介绍了一种设计热释电材料电性能测量系统的新方法,重点研究了pA级电流放大电路的设计.系统由温度控制和性能参数测量两大部分组成,采用计算机进行控制,利用该测量系统,可以同时得到热释电系数、介电常数和损耗与温度的关系曲线.用所研制的测量系统对掺锑、锰的PZT厚膜材料样品进行了热释电性能测量,给出了有关测量结果.     

动态电流法热释电系数测试系统结构设计

设计了一个热释电系数测试系统,用它来评价热释电材料的性能。系统基于动态电流法原理,由热释电样品加热、温度测量、升降温速度控制、热释电电流测量和测量数据处理5个部分构成。利用系统测得热释电材料样品的热释电系数峰值为1.98×10-7C/(cm2.℃),符合有关文献的报道,表明测试系统的性能良好。     

计算机反馈控制型单串口热释电系数测试系统

对热释电系数测试系统进行了研究,用单串口取代多串口,降低了系统连线的复杂度,提高了系统运行的稳定性;加入计算机控温机制,实现了计算机反馈控制加热炉升温速率,极大地提高了升温曲线的线性度,其线性度达到0.37%,从而消除了加热炉升温滞后性带来的测量误差,提高了测量的准确性.用几种热释电材料对现有系统进行了验证,实验表明新热释电系数测试系统的测试结果与理论数据相符,该系统已经可以较准确测量热释电材料的热释电系数.     

基于串口通信的热释电系数测试系统设计

阐述了一种基于PC机的热释电系数自动测试系统,介绍了利用Delphi7开发的串口通信和数据处理程序,并给出了主要源代码,利用该测量系统可以获得热释电系数与温度的关系曲线.     

退火热处理对钛酸锶钡陶瓷介电性能的影响研究

钛酸锶钡(BST)是钛酸锶(SrTiO3)固溶于钛酸钡(BaTiO3)而形成的固溶体,是一种重要的电子陶瓷材料.本文选择烧结温度为1420℃的BST陶瓷作为研究对象,为挖掘其性能潜力,探索退火热处理时间因素对BST陶瓷介电性能的影响,研究不同退火时间后,BST陶瓷的介电常数、损耗、可调性、击穿强度的影响,研究表明,退火热处理能提高BST陶瓷的可调性、击穿强度,降低其介电常数与损耗.     

压缩气体高压电容器电压系数测量方法

综述了压缩气体高压电容器电压系数测量的国内外研究状况。介绍了基于高压电容器电极结构、参数(如弹性模量)、安装精度等参数的测量估计其电压系数的间接测量法,分析了直接比较法、直流偏压法、双频法、倾斜法、冲击法等设计高压测试电路的方法,在实际工作电压下测试电压系数的直接测量法,其中重点解析了倾斜法。     

直流调速系统计算机辅助设计软件开发

针对直流调速系统的分析与设计,开发了基于VB与MATLAB计算机辅助设计软件,其中VB作为前端开发环境,MATLAB作为后端仿真工具,在软件的实现中,阐述了基于ActiveX的VB与MATLAB混合编程技术,同时就利用SIMULINK实现系统仿真,仿真曲线与文本、图形的显示等关键技术作了必要说明.直流调速系统计算机辅助设计软件的开发对于工程设计具有一定的应用价值.     

各向异性材料光学常数全自动椭偏测仪

本文介绍了一套将光度式旋转检偏器椭偏(RAE)系统同改变环境媒质、改变样品方位角、改变入射角相结合的全部测试过程由计算机控制的椭偏测试系统VMAE。它是通过改变环境媒质、光入射角以及自动改变样品方位角等方法测量多组椭偏参数,得到足够的独立方程,并通过计算机采用三种优化Powell,单纯形,转轴法方法求解多峰值超越方程组以研究光轴垂直、平行于表面的各向异性体、膜材料光学性能。并研制了一套除适用上述方法外还可兼容多波长法、多厚度法等方法的功能全面的模块集成化软件。最后通过比较实验结果与理论值的方法对系统的可靠性进行了验证。     

冲击信号测量系统中下限频率的正确选取

本文通过分析冲击信号测量系统下限频率对三种典型冲击信号测量的影响，得出一组冲击信号脉宽及峰值的测试误差与系统下限频率、信号脉宽之间的关系曲线。同时，本文还给出了一套在给定误差的条件下，正确选取冲击信号测量系统下限频率的方法。关键词：     

计算机辅助实验系统在振动测试教学中的应用

介绍了计算机辅助测试实验系统的组成及工作过程,阐述了计算机辅助实验测试系统对柔性转子轴临界转速的测定原理、方法及步骤,与传统测量方法相比大大提高了测量精度和测量效率.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.