基于VXI总线的新型AWG的设计

基于VXI总线的任意波形发生器是随着计算机技术和微电子技术在测试仪器中的应用而形成和发展起来的一类新型测试仪器。任意波形发生器的价值在于它能真正产生任意波形。文中提出了一种新型的任意波形发生器结构，介绍了基于VXI总线C尺寸任意波形发生器设计的全过程，开发了VXI总线寄存器基接口、用DDS技术设计了功能电路、开发了AWG的软面板、应用控制程序和仪器驱动器，所设计的任意波形发生器的特点是：高速、模块化、方便的波形输入以及和VXI资源相结合。该任意波形发生器模块已应用于模块化雷达自动测试设备中，能提供测试系统所需要的任何波形激励信号。     

基于PC总线的任意波形发生器设计

本文讨论了基于PC总线的任意波形发生器的系统设计方法。给出了PC总线任意波形发生器的系统结构形式，简要地介绍了仪器驱动程序和任意波形产生方法．这对于同类问题研究具有借鉴意义．     

HP33120A函数/任意波发生器的计算机控制

针对HP33120A函数/任意波形发生器测量功能扩展,本文介绍了运用GPIB接口和虚拟仪器编程语言LabVIEW设计开发的HP33120A计算机控制软件.该软件支持用户绘制、编辑、存储并输出任意波形,同时实现了台式仪器网络共享.     

计算机与可编程仪器的串行通信

介绍基于VXIplug&play和SCPI的仪器通信架构 ,着重阐述了应用编程框架层的各组成部分的特点和功能 ,并以惠普公司HP3 3 12 0A函数 /任意波形发生器为例介绍了仪器的VisualBASIC串行通信     

智能仪器程控接口配置方法

本文以Agilent公司生产的33500系列函数/任意波形发生器为例,介绍了其GPIB、USB和LAN三种程控接口仪器前面板配置过程及利用其SCPI命令实现配置的方法。该方法对充分发挥其程控功能和程序设计者具有很高参考借鉴价值。     

仪器和相关产品动态

PXI 5124数字化仪/PXI 5422任意波形发生器 2003年8月,NI推出了100MS/s的混合信号测试平台,这 是一套具有同步和存储结构(SynchronizationandMemoryCore, SMC)的模拟和数字仪器。日前,NI又推出了新款PXI 5124数 字化仪和PXI 5422任意波形发生器。它们扩展了SMC结构, 采样率加     

基于单片机的数字合成波形发生器

本文以AD公司的AD9857直接数字合成芯片为核心,设计了一种结构简便性能优良的数字合成波形发生器。文中主要对微机控制的任意波形发生器的软硬件设计进行了相应的研究,该数字合成波形发生器以INTEL公司的高性能单片机AT89C52作为控制器,利用了AD9857的DAC模式组成任意波产生的电路,在硬件电路的设计中使用可编程门阵列器件对一些特殊的电路进行了设计。该任意波形发生器不仅能产生正弦波,方波,三角波等常用的标准信号,还可根据用户的需要生成任意波形。     

基于GPIB总线的任意波形信号发生器自动测试系统设计

本文介绍基于GPIB总线的任意波形信号发生器自动测试系统的设计,详细阐述系统的硬件组成和软件设计。该系统采用Microsoft最新的Visual Studio.NET(VS)平台,实现对任意波形发生器的实时测量控制、测量结果处理以及数据库设计等,从而大大提高任意波形发生器的测试精度和测试效率。经使用验证,可用于实际测试中。     

基于LabVIEW快捷键应用研究

针对在LabVIEW开发环境中,利用快捷键设计满足用户要求、操作效率更高的程序问题,以控制33220A函数任意波形发生器为例,对利用控件属性自定义快捷键、事件结构实现快捷键的应用进行了研究,对程序设计者提高软件开发效率、增加应用程序人性化设计,具有重要的参考借鉴价值。     

基于高阶∑-Δ调制的任意波形发生器

高信噪比、高精度的校准激励信号源是设备自校准、电子测量及系统辨识等应用中所必须具备的.结合过采样技术,设计并实际研制了一种新型的任意波形发生器.该架构采用高阶∑-△调制技术,能有效降低实现系统工作频段内高信噪比性能所需的转换器位数及过采样率,改善硬件电路设计的复杂度.实际测量结果表明:当任意波形发生器中的调制后信号的数据字长与数模转换器组件的实际使用位数仅为8位时,即可以在有用频带内产生理想14位精度的高准确度的校准或测试信号.     

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.