硬质合金磁饱和测量的高精度数据处理方法

设计并验证了硬质合金磁饱和测量的一种高精度的数据处理方法,包括数字滤波、数字积分、数据拟合、系统调零和补偿等。滤波采用基于窗函数设计的有限长脉冲响应数字滤波器,积分采用复化Newton-Cotes积分算法,数据拟合采用改进的最小二乘法,系统校准采用首次调零和负值补偿方法。与传统硬质合金磁饱和测量的数据处理方法相比,该方法具有处理结果精度高、数据重复性好等特点。     

Automatic Measuring System for a Control of Standard Cells

The automatic measuring system developed in the Electrotechnical Laboratory to monitor standard cells requiring a lot of measurements is described. It is composed of a scanner, an integrating-type digital voltmeter, a programmer or minicomputer, etc., and carries out the data acquisition and processing for a maximum of 200 cells. The difference in EMF of two cells is measured precisely. To reduce the effect of the induced EMF in the scanner, a delay unit is provided, and procedures minimizing errors and evaluating random errors have been adopted. In the on-line version of system, a great part of the data processing is done during the delay and integrating time of digital voltmeter. Applying this system to the measurement of standard cells, a precision of the order of 0.1 ?V has been obtained.     

基于FPGA延迟线插入法的半导体激光测距

为了提高系统的集成度,同时兼顾精度,介绍用FPGA延迟线插入法采实现较高精度的脉冲激光测时、测距的原理和技术途径.FPGA延迟线插入法是在直接计数法的基础上,采用FPGA内部延时单元将时间间隔转化为数字量,经高速锁存器锁存后得到代表延时信息的温度计编码值来实现高分辨率的时间测量.提出了一种实用的高速时钟下(400 MHz)延迟线延时信息的锁存方法,并设计了FPGA时间数字转换电路及其延迟单元时间测量电路.测试结果表明,FPGA延迟线插入法可以将单点时间分辨率提高到80 ps,多次测量可达40 ps,对应距离分辨率为毫米级.将其应用于脉冲激光测距系统,进行了测距实验研究,给出了实验数据和测量误差分析,最终得到±10 cm的测距精度.     

基于虚拟仪器的慢速烤燃系统的设计及应用

为了满足不敏感炸药的发展需求,在GJB 772A-1997及行业内标准烤燃装置的基础上,设计并开发了一套慢速烤燃系统。该系统基于LabVIEW程序的控制软件,由以控制器、数据采集卡、热电偶及数字I/O卡等为主的典型硬件构成。参照美军标MIL-STD-2105D和国内行业标准,对该系统的适用性开展了试验研究;采用RDX基与HMX基两种典型的混合炸药装药进行了慢速烤燃试验。结果表明,该慢速烤燃系统具有广泛的温度适用范围,试验数据拟合相关系数不低于0.999 8,在0.055、0.200、1.000、2.000℃/min和3.000℃/min等几种升温速率条件下,炸药均能实现较高精度的线性升温。与RDX基混合炸药相比,HMX基混合炸药响应程度有所缓和。该慢速烤燃系统满足试验需求,可为研究炸药的热不敏感性提供有效手段。     

Characterization of a CCD-based digital x-ray imaging system for small-animal studies: properties of spatial resolution

A digital x-ray imaging system was designed for small-animal studies. This system is a fiber-optics taper-coupled imaging system with two CCD arrays uniquely jointed. The x-ray source of the system has a small focal spot of 20 microm. This digital imaging system contains specially designed shelves to provide magnification levels, ranging from 1.5x to 5x. The system is characterized in terms of its properties of spatial resolution. An observer-based spatial resolution measurement was conducted with a line-pair target and a sector test pattern. The modulation transfer function of the system, with different magnifications, was studied by use of a 10-microm lead slit. The average resolutions at 50% and 5% modulations at 1x magnification were measured as 3.9 and 8.4 lp/mm, respectively, where lp indicates line pairs. With 5x magnification, the 50% and the 5% modulations provided 13.2- and 29.9-lp/mm, respectively, average spatial resolutions. The measurements showed consistency between the two individual CCD arrays; the difference in resolution between the two CCDs is less than 1%, even at high magnifications.     

小型微纳米图形电子束曝光制作系统(英文)

为了满足科学实验过程中对制作半导体器件和微纳米结构的需要,同时避免受到昂贵的工业级电子束曝光(electron beam lithography,EBL)机的条件制约,构建了一种基于普通扫描电子显微镜(scanning electron microsco-py,SEM)的桌面级小型电子束曝光系统.建立了以浮点DSP为控制核心的高速图形发生器硬件系统.利用线性计算方法实现了电子束曝光场的增益、旋转和位移的校正算法.在本曝光系统中应用了新型压电陶瓷电机驱动的精密位移台来实现纳米级定位.利用此位移台所具有的纳米定位能力,采用标记追逐法实现了电子束曝光场尺寸和形状的校准.电子束曝光实验结果表明,场拼接及套刻精度误差小于100 nm.为了测试曝光分辨率,在PMMA抗蚀剂上完成了宽度为30 nm的密集线条曝光实验.利用此系统,在负胶SU8和双层PMMA胶表面进行了曝光实验;并通过电子束拼接和套刻工艺实现了氮化物相变存储器微电极的电子束曝光工艺.     

Automated Digital Measurements of CV Curves and Derivatives, and of Capacitance Transients for Semiconductor Evaluation

A system of instruments is presented for automated digital measurements of voltage and/or time dependent capacitances. The system has been designed for the evaluation of semiconductor materials and devices. It is based on a fast capacitance-inverse-to-frequency converter (FCFC), where a direct conversion is obtained with high accuracy, and where the device to be tested can be subject to dc, modulated, and pulsed voltage bias. The output frequency (of the order of 1 MHz) accurately foliows capacitance variations, even if occurring in short times (less than 100 Ms). Biasing circuits, a multichannel scaler, and logic interface circuits complete the system. Stationary and nonstationary CV curves and time variations of capacitances can be accuratety measured. The precision can be improved by averagng over many repetitions of the measurement. Derivatives (first and higher orders) of CV curves can also be directly and accurately measured by using a technique based on voltage modulation and synchronous reversible counting. This feature also makes it possible to obtain accurate measurements of doping profiles in semiconductors. Representative experimental results obtained with the system are shown.     

Real time spectrum analysis

Spectrum analysis in a real time environment is achieved in a recently developed instrument. All incoming pulses are digitized and digital windows set to define up to 50 regions of interest (ROIs). Up to 20 outputs (analog, relay, digital), defined by combining the count rates of ROIs and standard mathematical functions, are recalculated as frequently as once per second. User defined time response and wide range of smoothing functions allow the outputs to be selected according to the measurement requirements. The characteristics of a number of smoothing functions are analyzed and compared. Examples are given of high precision radioactivity measurements in dynamic environments.     

A high accuracy microwave ranging system for industrialapplications

A microwave ranging system that employs a composite frequency modulated continuous wave/continuous wave (FMCW/CW) measurement technique is described. Conventional FMCW radar techniques are employed to find the approximate range of the target. An ambiguous but very accurate set of range solutions is also determined through a CW measurement. The correct, precision CW distance measurement is resolved on the basis of the approximate FMCW solution. An adaptive, spatial digital filtering routine applied to the FMCW radar measurements reduces the influence of clutter, ensuring reliable operation. An X-band prototype system that achieves submillimeter accuracy is described     

Contactless testing of small-module gears

Conclusions Contactless measurements provide the required prerequisites for testing the entire range of gear modules specified by the precision instrument-making standard. The digital instruments for contactless testing can be made up from integrated circuits. The application of the contactless testing method with digital processing and presentation of the measured information will ensure high precision and efficiency for completely automatic measurements.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 29–31, June, 1977.     

Distributed architecture of an adaptive positioning servo

A distributed computer architecture which offers high precision and high-speed computing capabilities that are needed when complex system identification and controller adaptation algorithms are implemented in real time. The distributed implementation offers high immunity against external disturbances. An elevator control application is considered. However, the principles presented are applicable to different types of industrial automation problems. The individual computer units in this system are programmable VLSI signal processors (e.g. TMS-320C25). All the precision-sensitive computations are performed using simulated single-precision floating-point arithmetic (IEEE Standard 754). This is possible because of the high speed of the signal processor and low sampling rate (i.e. ⩽100 Hz) of the entire positioning servo. The communication between the master controller and the slave units is coordinated by a simple communication protocol that utilizes a prediction-type transmission error correction principle     

基于时幅转换插入法的脉冲激光测距

针对传统脉冲激光测距直接计数法精度低的问题,本文介绍用时幅转换插入法来提高脉冲激光测距时间测量分辨率和测距精度的原理和技术途径.提出了时幅转换电路设计中的几个关键问题.在脉冲激光测距实验平中对设计的时幅转换电路进行了性能测试实验.结果表明,时幅转换插入法将时间测量分辨率由10 ns 提高到20ps ,测距精度由1.5 m 提高到5 cm .最后分析了影响脉冲激光测距精度的误差因素.     

Characterizing an Image Intensifier in a Full-Field Range Imaging System

We are developing a high precision full-field range imaging system. An integral component in this system is an image intensifier, which is modulated at frequencies up to 100 MHz. The range measurement precision is dictated by the image intensifier performance, in particular, the achievable modulation frequency, modulation depth, and waveform shape. By characterizing the image intensifier response, undesirable effects can be observed and quantified with regards to the consequence on the resulting range measurements, and the optimal operating conditions can be selected to minimize these disturbances.      

闭环光纤陀螺数字控制器的设计与仿真

数字闭环光纤陀螺可以看作一个数字控制系统,根据陀螺工作原理推导出系统离散传递函数。为消除稳态误差及改善零偏稳定性,数字控制器中加入积分环节和滑动平均滤波器,并引入PID 控制算法改善系统动态特性。根轨迹分析表明,控制器增益过大将引起系统不稳定。仿真结果显示,加入综合所得数字控制器,可以满足陀螺实际应用需要。     

Digital Photoelasticity: Principles, Practice and Potential

The enormously enhanced power of photoelasticity resulting from adoption of digital technologies is highlighted and discussed. An overview of the principal techniques of digital fringe processing is provided within a single theoretical framework. The practical application of the new technologies using both conventional instruments and novel optical devices is discussed. Experiments involving more 1 × 10⁶ quantitative fringe order measurements are possible and practical on a routine basis using the current technology. Products based on this research are beginning to appear on the market so that many new application areas are opening up for photoelasticity, such as dynamic events, real‐time fatigue crack analysis, monitoring polarisation changes at a microscopic level in materials; detailed validation of numerical simulations, particularly of complex geometry and loading; and in‐service monitoring using reflection photoelasticity of damage in both homogeneous and heterogeneous materials, such as composites.     

变结构PID在微机械陀螺仪闭环驱动电路中的应用

为满足微机械陀螺仪(MMG)闭环驱动电路起振快速、无超调且稳态精度高等要求,提出了一种基于FPGA的数字化变结构PID控制器,并以其为核心构建了微机械陀螺仪的数字化闭环驱动电路.通过构造以控制误差为自变量的比例增益、积分增益和微分增益函数,使变结构PID的结构和参数能够根据瞬时误差的变化而变化,以提高闭环驱动电路的性能.针对某型微机械陀螺仪敏感结构参数,进行了SIMULINK仿真,仿真结果表明以变结构PID为核心的闭环驱动电路是可行的.起振实验结果表明,经典PID构成的闭环驱动电路,其检测电压的幅值超调量达到了75%,稳定时间为2 s;采用变结构PID控制器后闭环驱动检测电压的幅值无超调且稳定时间为0.7 s;1 h的稳定性实验表明,采用经典PID时检测电压幅值的长期稳定性为2.73×10-5V,采用变结构PID时其稳定性为2.68×10-5V,证明变结构PID可以兼顾系统在快速性、超调量和稳态精度等方面的要求.     

Multilateration with the wide-angle airborne laser ranging system: positioning precision and atmospheric effects

Numerical simulations based on previously validated models for the wide-angle airborne laser ranging system are used here for assessing the precision in coordinate estimates of ground-based cube-corner retroreflectors (CCR's). It is shown that the precision can be optimized to first order as a function of instrument performance, number of laser shots (LS's), and network size. Laser beam divergence, aircraft altitude, and CCR density are only second-order parameters, provided that the number of echoes per LS is greater than 20. Thus precision in the vertical is ~1 mm, with a signal-to-noise ratio of 50 at nadir, a 10-km altitude, a 20 degrees beam divergence, and ~5 x 10(3) measurements. Scintillation and fair-weather cumulus clouds usually have negligible influence on the estimates. Laser biases and path delay are compensated for by adjustment of aircraft offsets. The predominant atmospheric effect is with mesoscale nonuniform horizontal temperature gradients, which might lead to biases near 0.5 mm.     

A 100 A, 100 kHz transconductance amplifier

A high-current, wide-band transconductance amplifier is described that provides an unprecedented level of output current at high frequencies with exceptional stability. It is capable of converting a signal voltage applied to its input into a ground-referenced output rms current up to 100 A over a frequency range from DC to 100 kHz with a useable frequency extending to 1 MHz. The amplifier has a 1000-W output capability ±10 V of compliance, and can deliver up to 400 A of pulsed peak-to-peak current. The amplifier design is based on the principle of paralleling a number of precision bipolar voltage-to-current converters. The design incorporates a unique ranging system controlled by opto-isolated switches, which permit a full-scale range from 5 A to 100 A. The design considerations for maintaining wide bandwidth, high output impedance, and unconditional stability for all loads are discussed     

CMOS Monolithic Metal–Oxide Gas Sensor Microsystems

This paper presents two mixed-signal monolithic gas sensor microsystems fabricated in standard 0.8-$muhbox m$CMOS technology combined with post-CMOS micromachining to form the microhotplates. The on-chip microhotplates provide very high temperatures (between 200$^circ$C and 400$^circ$C), which are necessary for the normal operation of metal–oxide sensing layers. The first microsystem has a single-ended architecture comprising a microhotplate (diameter of 300$muhbox m$) and a digital proportional-integral-derivative (PID) microhotplate temperature controller. The second microsystem has a fully-differential architecture comprising an array of three microhotplates (diameter of 100$muhbox m$) and three digital PID microhotplate temperature controllers (one controller per microhotplate). The on-chip digital PID temperature controllers can accurately adjust the microhotplate temperatures up to 400$^circ$C with a resolution of 2$^circ$C. Further, both microsystems feature on-chip logarithmic converters for the readout of the metal–oxide resistors (which cover a measurement range between 1$hbox kOmega$and 10$hbox MOmega$), 10-bit A/D converters, anti-aliasing filters, 10-bit D/A converters,$I ^2 C$serial interfaces, and bulk-chip temperature sensors. Carbon monoxide (CO) concentrations in the sub-parts-per-million (ppm) range are detectable, and a resolution of 0.2 ppm CO has been achieved.     

Pid数字化控制在箱式炉中的应用

介绍了采用Pid数字化温度控制仪表及双向可控硅的开关对箱式电阻炉的电气控制系统进行技术改造,整个电气控制系统构成由Pid数字化温度控制系统、箱式炉主电源、超温报警系统以及工作温度时间打印系统等组成。Pid数字化温度控制仪表采用了ALTEC公司PC900型温度智能控制器,阐述了系统功能及工作原理。