动态光电显微镜刻线瞄准信号的处理方法

研究了激光干涉比长仪的动态光电显微镜刻线瞄准信号的处理方法。分析了基于硬件电路的信号处理方法,及基于高速A/D采样、计算机数据处理的软硬件结合的信号处理方法,分别介绍了这两种方法的系统组成及工作原理。实验证明,前者抗干扰性能差,瞄准精度低;后者实现对刻线信号均匀等距采样,瞄准精度高,在测量速度达3mm/s时,可实现2nm的瞄准分辨率。     

基于高速A／D卡的全波形采集超声自动检测系统

设计了一种全波形采集超声自动检测系统,实现了A,B,C 3种扫描方式且具有记录被检材料上所有检测点超声A扫描波形的功能,支持材料超声检测、评价技术研究.该系统由高速A/D卡、超声检测仪、自动扫描器、运动控制系统和CSCAN软件等组成,作为核心部件的高速A/D卡选用PCI-9820型,负责从超声检测仪采集A扫描波形信号.自动扫描过程中,A/D卡与超声检测仪、运动控制系统之间通过硬件信号实现同步,使A扫描波形数据的采集与被检材料上声传播的渡越时间、预定测量点位置相对应,采集得到的A扫描波形数据通过A/D卡的板载SDRAM及DMA功能异步传输至计算机内存,并由CSCAN软件进一步实现数据压缩、滤波、存储以及不同方式成像等处理.测试结果证明,该系统运行速度快,成像精度高且性能稳定. 更多还原     

USB多路数据采集器

针对目前大多数采集系统无法实现多通道高分辨率采样及携带不方便等情况,提出了一种基于USB的多路数据采集系统的设计方法。系统利用ARM+FPGA+AD7656的系统组合实现16路通道同步信号采样,FPGA用于实现对A/D转换的逻辑控制,通过ARM7处理器对A/D转换数据进行处理,再由USB接口与计算机进行数据通信。测试结果表明,基于FPGA与ARM的多通道数据采集系统结构简单、控制方便、设计成本较低,能够准确快速地对16路信号同时进行采集。     

2m比长仪纳米级高精度刻线自动瞄准系统

阐述了2m比长仪刻线瞄准系统的组成,对其光电显微刻线成像的原理及刻线图像信号进行了分析,根据其刻线信号的特点,研究了其高精度的刻线信号自动处理系统,该系统基于FPGA现场可编程电路技术,实现刻线信号的自动门控触发、自动滤除虚假刻线信号,配合计算机信号自动处理软件可以实现刻线测量的高精度自动瞄准.最后对2m比长仪的瞄准精度进行了测试实验,实验结果表明,测量金属标准线纹尺时,2m比长仪单次测量刻线瞄准精度优于10nm(1σ).     

光纤传感式红外水分测定方法的研究

将光纤传感技术与传统的红外水分测定方法相结合,设计了一种光纤束传感器来实现发射光和接收光的传输.为将接收二极管上的微弱信号送到A/D转换器处理,采用锁定放大原理设计接收信号的调理电路.在不影响测量精度的情况下,能使红外水分测定系统变得更简单、更廉价.     

膜式燃气表气密性检测仪的研制

针对现今出现的越来越多的燃气使用安全问题,介绍了燃气表气密性检测在日常生活中的必要性以及重要意义,并且设计了基于直压法原理的以C8051F350单片机为控制核心的气密性检测仪系统.该系统采用主、副控制板分级控制的形式,在检测时更具有灵活性.同时利用高精度差压变送器测量压力,并通过24位A/D转换器对检测信号进行处理,从而实现对微小信号的捕获和放大.最后通过不确定度分析证实所得实验数据满足要求.     

一种基于PIC16F877的温度显示报警装置的设计与实现

本文使用铂热电阻PT100作为温度测量传感器,采用三线制桥式电路将非电量的温度信号转换为电压信号,并通过集成A/D转换技术的单片机PIC16F877完成数据采集、处理、显示,实现了对温度的精确测量报警.     

基于AD590四路巡检数字温度计的设计

本文介绍了一种可对四路温度进行数字显示的温度巡检仪,其包含:温度信号检测及转换部分、四路巡检部分、A/D转换及数字显示三大部分。该系统的工作原理为:AD590传感器将温度信号转化成电流信号,经放大电路变换成与温度成线性关系的电压信号,再由数字控制电路送到A/D转换器,最后通过数字显示器显示出测量的温度.其测量范围为-55℃~150℃,具有实用性强、可靠性高、测量精度高等特点。     

光栅莫尔条纹细分及辨向方法研究

提出了一些新的基于数字处理技术的莫尔信号细分及辨向方法.单光栅副莫尔条纹采用差值细分方法;双光栅副莫尔条纹采用乘积细分法.将信号进行区间划来实现辨向.实验采用DSP器件内置的高速A/D模块实现数/模转换,利用DSP专用指令实现信号的滤波、细分和辨向.实验结果表明,单光栅副和多光栅副的细分精度分别为3"和0.3".     

管道泄漏数学模型及测试技术

通过分析建立管道泄漏数学模型,研究泄漏引发的瞬态负压波在管道中的传播过程,编制离线软件模拟管道泄漏事故.在此基础上,运用瞬态负压波法在实验环道上进行泄漏监测实验.实验数据采集系统由HB26S型扩散硅压力传感器和PCI-1800L型A/D采集转换芯片组成,采集设在环道首末端处监测点的压力信号,并以此信号判断泄漏是否发生.运用信号相关处理方法对环道首末端监测点的压力信号进行处理,得到泄漏引发的瞬态负压波传播到环道首末端监测点的时间差,实现漏点的定位.实验结果验证了瞬态负压波泄漏检测方法的有效性和极性相关漏点定位法准确性.     

一句话、一个人和一本书影响了我

Q=你应该从大二就开始了兼职设计工作。当初什么样的机会让你和设计有了实践上的接轨？当时的你最希望从实践中获得的东西是什么？后来到底得到了怎样的收获？A——我初次参与设计兼职工作是在大二时的暑假。一个偶然的机会．有朋友介绍我与其他两位同学与几家展览公司进行一些接触。当时是上海会展行业初步呈现规模、开始发展壮大的时期．有些展示公司由于业务繁忙，需要一些勤奋肯干的兼职学生参与设计，于是就有机会开始了最初的实践。后来也逐渐接触了另几家会展公司,参与了更多的展示设计工作，可以说基本上在大学的设计实践绎聆伞部来自干展示展览设计．     

A Noise-Tolerant Hybrid Model of A Global and A Local Learning Module

Proposed is GLLL2, a hybrid architecture of a global and a local learning module, which learns default and exceptional knowledge respectively from noisy examples. The global learning module, which is a feedforward neural network, captures global trends gradually, while the local learning module stores local exceptions quickly. The latter module distinguishes noise from exceptions, and learns only exceptions, which makes GLLL2 noise-tolerant. The results of experiments show the process in which training examples are formed into default and exceptional knowledge, and demonstrate that the predictive accuracy, the space efficiency, and the training efficiency of GLLL2 is higher than those of each individual module.

     

压电材料中反平面渗透裂纹的解

用复变函数的保角映射法,采用可渗透边界条件,研究了含裂纹的无限大压电材料在平面内电场和反平面荷载作用下的耦合场,得到了精确的解和场强度因子以及能量释放率。结果表明,电场强度在裂尖没有奇异性,应变、应力、电位移具有1/2阶的奇异性,能量释放率总是正的。     

GENERATING A LAYOUT FROM A DESIGN SKELETON

In the past, researchers have proposed several types of design skeletons from which a human designer can generate good facilities layouts. Examples are flow graphs, SLP space relationships, bubble diagrams, planar adjacency graphs, matching based adjacency graphs, centroid locations, and cut trees. In this paper, we introduce a linear programming model which efficiently generates a layout from a graphical representation of any design skeleton. We demonstrate how the model can be used to enhance most design skeleton based layout approaches.     

A GENERALIZED CONCEPT OF A FATIGUE THRESHOLD

Abstract— The conditions for non-propagating LEFM type fatigue cracks were investigated on an Inconel, 617 Alloy in the range of K _max between 10 and 50 MPa m^1/2 under four different types of fatigue loading conditions. In all tests, K _max was held constant during the fatigue cycling prior to determining the non-propagation condition. It was found that with decreasing range of applied K the fatigue tolerance range Δ K _{eff, th} increases. Furthermore, there is slight increase of Δ K _eff,th with decreasing K _max of approximately 20–30% when K _max is decreased from 50 to 10 MPa m^1/2. The results of the four types of tests are considered in respect to the damage in the near-region of the crack front, i.e. increasing K _max increases the damage zone and therefore decreases the fatigue tolerance range Δ K _eff,th.     

A switched-capacitor successive-approximation A/D converter

A switched-capacitor successive-approximation analog-to-digital (A/D) converter that incorporates a serial digital-to-analog (D/A) subconverter for generating the threshold voltage sequence is developed. The conversion process is insensitive to parasitic capacitances and offset voltages of the comparator and operational amplifiers. Error analyses and Spice simulations show that a resolution higher than 11 b, a sampling rate up to 440 ksamples/s with 10-b resolution, and a power consumption less than 60 mW are attainable with monolithic implementation using present CMOS technologies. The required chip area is small because of a low device count. The architecture described is therefore best suited for high-accuracy, medium-speed A/D converters in application-specific integrated circuits (ASICs). A prototype converter breadboarded using discrete components has confirmed the principles of operation     

Linear and Nonlinear A/D, D/A, A/A Conversions Using the Dual-Slope Principle

New methods for precise linear and nonlinear A/D, A/A, and D/A transformations, based on the principle of the dual-slope conversion are proposed. These methods enable multiplication, exponential and logarithmic conversion, determination of nth roots, and the solution of polynomial equations to be performed during the conversion cycle.