分立型电压电流探头的原位标定

利用分立型电压、电流探头和数字示波器测量脉冲射频功率存在探头相位标定的问题,造成难以精确测量脉冲射频功率,特别是脉冲射频放电初始击穿段的功率。文中研究了影响探头相位标定的因素,获得了分立型电压、电流探头相位校正因子。经过比较,测量的脉冲射频功率与光电倍增管记录的放电辉光变化规律基本一致,证实了标定后的分立型电压、电流探头可以用于脉冲射频功率精确测量。     

分散控制系统的电磁兼容性设计

从分散型控制系统的特性以及使用的环境看，干扰种类主要包括静电放电、射频电磁场辐射、电快速瞬变脉冲群、浪涌(冲击)、射频场感应的传导骚扰、工频磁场、短时中断和电压变化七类．站在设计的角度，如何避免这些骚扰源的干扰，下面是我们的一些经验。     

振荡冲击电压下局部放电检测系统研究

为了研究振荡冲击电压下局部放电现象,设计了振荡冲击波形发生器,根据等效电路模型,推导出波形参数表达式;制作了一款专门用于冲击电压下局部放电脉冲测量的高频电流传感器,研究了线圈匝数和积分电阻对其频率特性的影响,利用函数发生器和方波电压源测试校准了传感器实际动态响应;在此基础上建立了一套局部放电脉冲测量系统,并对针板电极实验模型在振荡冲击电压下的局部放电信号进行测量.试验结果表明,该测量系统能够有效抑制源干扰,提取局部放电脉冲,为进一步研究振荡冲击电压下局部放电特征和机理提供重要价值.     

显示仪表应用中的干扰分析

１序言显示仪表在工业生产或试验现场中使用时的条件常常是很复杂的。被测量的参数往往被转换成微弱的低电平电压信号，并经过长距离传输到显示仪表，因此除有用的信号外，由于各种原因，经常会有一些与被测信号无关的电流或电压存在，这种无夫的电流或电压称为“干扰”。热噪声、温度效应、化学效应、振动等都可能给测量带来影响，它将歪曲测量的结果，严重时甚至会使仪表完全不能工作。２于扰的形式根据仪表输入端于扰的作用方式，可分为串模于扰和共模干扰。如图１所示，串模干扰（又称常态干扰、横向干扰、差模干扰）是叠加在被测信号上…     

PCI-9846高速数字化仪在电火花放电特性测试中的应用

针对电火花放电间隙状态变化特性的检测与分析等问题,利用凌华PCI-9846四通道高速数字化仪建立了测量系统,讨论了电火花加工放电间隙放电特性测量方案,测量了不同加工状态下放电间隙两端的电压波形和电流波形,分析了空载、正常火花放电、过渡电弧放电和短路等不同加工状态下的电压波形特征及其特征参数。研究结果表明,正常火花放电、过渡电弧放电和短路等不同加工状态下间隙电压的阈值范围不同,且与加工电流有关;在设计伺服控制器时,应根据电源电压、加工电流、工件材料等来动态修正电压阈值。     

组合式电子互感器的理论和实验研究

基于反射式偏振干涉原理和模间干涉原理，研制出一种新型的可同时测量母线上的电流和电压的组合式互感器。这种互感器绝缘结构简单，电压测量与电流测量间无相互干扰，为消除外界干扰、提高系统的测量精度提供了理论根据。     

电力输电线电流,电压的组合式光学测量

通过接地电容将输电线的电压转换为电流，在一个绝缘瓷套内可实现输电线电流、电压的组合式光学测量。对电流的测量，我们研制了一种双环路结构光学电流传感头，使灵敏度提高了一倍。对电压的间接测量，提出了采用频率分离的比较测量方案，可以消除外界干扰的影响。对这两种测量方案进行了模拟实验。     

伺服放大器的研究与改进

本文介绍的伺服放大器采用集成触发器与双向可控硅构成零电流交流开关,具有制造工艺简单、维修方便、射频干扰小和可靠性高等优点。文中对目前大量使用的电动执行器中的伺放电路进行了分析,介绍了改进电路的工作原理。     

串联电池组监测系统

介绍一个以51系列单片机为控制核心的串联电池组监测系统。重点是使用差分放大器解决对串联电池组进行电压测量时的共地问题和使用数字式温度测量芯片进行比较精确的温度测量。系统简单经济，经过试验，在要求的电压和温度指标下，能可靠、准确地对串联电池组进行监测。     

电火花加工单脉冲放电通道直径扩展规律研究

电火花加工的加工表面是由一系列的脉冲放电凹坑叠加而成的,因此研究单脉冲放电通道直径的扩展规律,对研究电火花加工的工艺规律以及加工表面质量预测等具有非常重要的意义。研究脉冲放电通道的形成与扩展机理,讨论电压、极值电流、脉宽等放电参数对放电通道直径扩展的影响,并根据理论推导建立了单脉冲放电通道直径扩展的数学模型。以煤油作为电介质工作液开展了单脉冲放电试验,使用超景深显微镜对单脉冲放电凹坑的直径进行了测量,并把测量得到的单脉冲放电直径数据代入建立的数学模型进行回归求解。回归公式的计算值与试验测量得到的单脉冲直径数据吻合度较高。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.