电机绕组绝缘阻值在线监测系统的设计

由多台仪表(数字兆欧表)通过RS-485总线与上位机PC机构成整个在线监控系统,上位PC机中的组态软件在线远程监控下位仪表自动测量烘干炉中电机绕组的绝缘阻值,并自动记录,存储、显示和打印数据.针对电机绕组的热态绝缘阻值较小,容易击穿的特点,自主研发一种具有通信功能的低压智能兆欧表;简述了监控系统的硬件框架组成;下位仪表的硬件设计、软件设计以及与上位机通信驱动程序的编写,并给出相应的流程图.     

兆欧表对绝缘电阻的自动化测量

兆欧表对绝缘电阻的自动化测量哈尔滨针织厂丁凤林，郑锦屏兆欧表是主要电工测量工具之一．广泛应用在电器安装、工厂维修以及教学科研等部门。在对电器产品质量考核进行绝缘电阻测量时．一般都使用兆欧表。兆欧表按供电方式不同主要可分为三类：手摇发电机式、干电池式和...     

DMG2671系列数字兆欧表

DMG2671数字兆欧表(CPA90E112-42、专利号91112625·X)取代了传统的绝缘电阻摇表,适用于测量通信、电力电缆线路、各种变压     

嵌入式控制的智能型数字兆欧表

随着电子技术及嵌入式技术的不断发展,传统手摇式兆欧表被智能型兆欧表所取代已是大势所趋。本文介绍一种用嵌入式实现的数字式电子兆欧表,它具有测量精度高、测量范围宽、数据处理能力强、显示直观稳定美观等优点。该方案对提高兆欧表的智能性、便携性,有一定的参考价值。     

兆欧表标度牌自动分选仪

介绍利用图像传感器检测兆欧表的一些特征值,通过微处理机自动检测、处理讯号,然后送往PC机,由PC机自动分选出适合该兆欧表的标度牌.     

基于ICL7135的智能型兆欧表的研制

随着电子技术和单片机技术的不断发展，传统的手摇式兆欧表被智能型兆欧表所取代已是大势所趋。本文介绍了基于ICL7135的智能型兆欧表的结构、功能及其实现技术。     

兆欧表的调修拾零

兆欧表的调修拾零山东省滨州地区计量测试检定所（２５６６１８）王燕兆欧表是电力部门、厂矿企业目前测量绝缘电阻不可缺少的主要仪器之一。兆欧表的准确与否直接影响线路、设备及人身的安全，为了保证兆欧表的准确性，必须学会兆欧表的维修，现就其常见故障介绍如下。（...     

排除感应电影响的兆欧表改造

目前在感应电较为强烈的变电场内,无法完成对设备进行绝缘电阻测量的试验,同时会损坏测量仪器兆欧表,甚至给绝缘电阻试验带来风险。基于上述情况,对常规兆欧表进行了相关研究,通过抗感应电改造,很大程度上解决了由于感应电强烈所造成的无法测量绝缘电阻的问题。     

ZC－7兆欧表检修技巧

ＺＣ－７兆欧表检修技巧ＺＣ－７兆欧表是最常用的电工仪表之一，从对该表的检修校准实践看，它的一些简易故障往往由于操作者拆装不当而扩大，为此提供几例检修小经验供初学者参考。１机械与电气故障的简易判别拿到一块兆欧表后，如果进行开路和短路试验，仪表指示不正常...     

数字现场工艺纪律管理系统

介绍了利用ASP.NET技术开发一套基于B/S模式的数字现场工艺纪律管理系统的方法,实现了对现场工艺纪律的数字化和动态化管理。同时对系统的体系结构、功能特点和技术难点进行了介绍。     

Surface electrode switching of a 16-electrode wireless EIT system using RF-based digital data transmission scheme with 8 channel encoder/decoder ICs

A Radio Frequency (RF) based digital data transmission scheme with 8 channel encoder/decoder ICs is proposed for surface electrode switching of a 16-electrode wireless Electrical Impedance Tomography (EIT) system. A RF based wireless digital data transmission module (WDDTM) is developed and the electrode switching of a EIT system is studied by analyzing the boundary data collected and the resistivity images of practical phantoms. An analog multiplexers based electrode switching module (ESM) is developed with analog multiplexers and switched with parallel digital data transmitted by a wireless transmitter/receiver (T_x/R_x) module working with radio frequency technology. Parallel digital bits are generated using NI USB 6251 card working in LabVIEW platform and sent to transmission module to transmit the digital data to the receiver end. The transmitter/receiver module developed is properly interfaced with the personal computer (PC) and practical phantoms through the ESM and USB based DAQ system respectively. It is observed that the digital bits required for multiplexer operation are sequentially generated by the digital output (D/O) ports of the DAQ card. Parallel to serial and serial to parallel conversion of digital data are suitably done by encoder and decoder ICs. Wireless digital data transmission module successfully transmitted and received the parallel data required for switching the current and voltage electrodes wirelessly. 1 mA, 50 kHz sinusoidal constant current is injected at the phantom boundary using common ground current injection protocol and the boundary potentials developed at the voltage electrodes are measured. Resistivity images of the practical phantoms are reconstructed from boundary data using EIDORS. Boundary data and the resistivity images reconstructed from the surface potentials are studied to assess the wireless digital data transmission system. Boundary data profiles of the practical phantom with different configurations show that the multiplexers are operating in the required sequence for common ground current injection protocol. The voltage peaks obtained at the proper positions in the boundary data profiles proved the sequential operation of multiplexers and successful wireless transmission of digital bits. Reconstructed images and their image parameters proved that the boundary data are successfully acquired by the DAQ system which in turn again indicates a sequential and proper operation of multiplexers as well as the successful wireless transmission of digital bits. Hence the developed RF based wireless digital data transmission module (WDDTM) is found suitable for transmitting digital bits required for electrode switching in wireless EIT data acquisition system.     

基于数字孪生的卫星总装过程管控系统

为解决卫星总装过程实时管控和分析预测的难题,提出一种基于数字孪生的卫星总装过程管控系统,建立了系统体系结构,研究了面向总装过程管控的产品与车间孪生建模、数据物联采集与虚实精准映射、数字孪生驱动的总装过程实时管控与分析预测、孪生数据多维度组织管理等关键技术。该系统以孪生模型和实时数据为驱动,基于产品关键特征和车间关键要素,将模型与数据进行有效融合,实现了总装过程的实时管控,并为生产决策提供支持。通过在卫星总装车间部署运行的应用效果,验证了该系统的有效性和可行性。     

基于数字孪生的生产车间运行状态在线预测

针对数字孪生车间的在线预测难题,提出一种实时数据驱动的数字孪生车间运行状态在线预测方法。分析了车间数字孪生体的内涵和运行机制,构建了基于车间数字孪生体的仿真预测框架,阐述了基于事件调度法的仿真运行逻辑,建立了数字孪生车间输入特性、样本生成、事件处理逻辑之间的关系,融合实时数据实现了基于持续瞬态仿真的车间在线预测。设计并开发了面向数字孪生车间的运行状态在线仿真系统,通过实例验证了该方法的可行性和有效性。     

基于数字孪生的数控设备互联互通及可视化

全球制造业正在向着智能化、规模化的方向快速发展,但是数控设备之间存在数据接口不统一、设备数据交互困难、现场设备状态监测成本较高等难题。现提出一种基于数字孪生的数控设备互联互通及可视化技术,首先利用三维激光扫描技术构建车间数控设备数字孪生模型,通过OPC UA通讯构架读取数控设备的实时运行数据,并转化格式后存入数据库作为指导虚拟现实引擎的源数据,使用Unity数据驱动引擎去驱动数字孪生模型,从而实现物理模型与数字孪生模型的同步运动。最后,对车间数控设备的生产过程进行了数字孪生技术的实现,验证了所提方案的有效性和正确性,为面向互联互通的数字孪生数控设备提供了技术支持。     

基于数据网格的远程教育系统

数据密集型计算的飞速发展以及数据量的迅速膨胀对信息处理能力的要求越来越高,在这种情况下,数据网格应运而生.它可以满足分布异构的海量信息高效处理的应用需求,广泛应用到地球科学、高能物理学、医学、协同制造与设计等领域,数字人即是其中之一.将数字人与远程教育相结合,建立一个局域网环境下的远程教育实验系统,借助于数字人模型,可实现授课、实习、讨论、检查与辅导等多种功能.其中基于网格思想的海量数据管理系统,为数字人海量数据集提供了高效、安全、透明的数据存取与访问机制.最后通过一个运行实例显示了本系统的正确性与可行性     

容栅数显尺与智能手机的无线连接

提出一种将容栅数显尺与智能手机无线连接组成轻便数据采集系统的方法,同时给出将容栅数显值转换为手机蓝牙信号的容栅-蓝牙接口方案。模拟测试结果表明,该系统可实现数显值的自动采集、处理与存储,具有体积小、重量轻、耗电低等优点,与PC机有线数据采集系统相比具有更大的推广应用价值。     

并行数字下变频中的NCO实现研究

受数字信号处理器件处理速度的制约,宽带数字中频处理带宽、滤波器性能等重要指标难以提高。硬件实现时FPGA(field programmable gate array)无法提供与采样率相匹配的数据处理速度直接对原始采样数据下变频,将多相结构应用到传统的数字下变频运算中。推导了应用于数字下变频多相结构的多路NCO(numerically controlled oscillator)数字本振信号数学表达式,并讨论了在FPGA中实现多路NCO时相关参数的选取原则。MATLAB仿真结果及硬件平台验证了采用多路NCO本振信号实现数字下变频的正确性。     

数显量具多通道数据采集系统的研制

介绍基于容栅式数显量具的多通道数据采集系统的开发与应用。着重介绍了系统原理以及软、硬件设计。该系统可以自动判别表以及卡尺等不同类型的容栅式数显量具产品,同时可容纳多通道量具测量的实时数据采集,并且可以将量具的测量数据传送到计算机,通过计算机上的接收软件对接收到的数据进行数据分析、统计等。     

Application of Modified Digital Halftoning Techniques to Data Hiding in Personalized Stamps

The objective of this research is to embed information in personalized stamps by modified digital halftoning techniques. The displaced and deformed halftone dots are used to encode data in the personalized stamps. Hidden information can be retrieved by either an optical decoder or digital image processing techniques.The results show that personalized stamps with value-added features like data hiding or digital watermarking can be successfully implemented.     

A simple point cloud data reduction method based on Akima spline interpolation for digital copying manufacture

Point cloud data acquisition is the first key step in digital copying manufacture. In order to reduce extremely dense acquired data while maintaining data accuracy, this paper presents a simple and practical on-line point cloud data reduction method for digital copying manufacture, which is based on Akima spline interpolation. The basic idea of this method is similar to sketch painting: Outline the broad contour of the curve first and then revise local details until the interpolated curve satisfies the required accuracy. In this method, Akima spline interpolation is adopted to connect acquired points for CNC machining in digital copying process. It obtains a smaller data reduction ratio and a smoother machined surface than conventional methods. Experimental results indicate that the proposed Akima reduction method is able to eliminate redundant data effectively under different required accuracy. The reduction performance of this method is superior to equal ATCD reduction method obviously under the same required accuracy. The proposed method can be used in the real-time data acquisition process of digital copying manufacture to replace traditional methods.