基于USB接口的电力系统参数采集系统设计

随着电力系统的供电质量要求增高，迫切需要实现电力系统参数实时采集，准确地得到电能质量参数，以服务于我国的工农业需求。本文选取谐波参数为采集的对象，采用新型高速A／D转换器ADS7864和低通滤波器提高谐波采集的精度和解决采集过程中的频谱泄漏问题。通过USB技术和LabVIEW实现对50周的谐波采集。     

离散傅里叶变换量化效应的研究

本文研究了DFT谐波分析中A/D转换器量化效应对谐波幅度和相位分析准确度的影响,并导出了误差传递关系式;讨论了在信号、系数(三角函数)量化效应同时存在时的谐波分析误差,并利用微小标准偏差准则研究了如何根据A/D转换器的量化位数来合理选择系数的量化位数,使系数量化引起的谐波分析误差与A/D转换器量化引起的误差相比可以忽略不计,同时又使DFT的计算量最小。结果表明,系数量化位数高于信号量化位数2～4位就已足够。     

ICL7135与单片机接口电路

针对双积分式A／D转换器对信号转换速率的要求不是很高而对转换精度要求很高的特点,分析了双积分式A／D转换器ICL7135与单片机的几种接口电路。对并行与串行两种方式进行说明;并行接口电路中根据占用单片机I／O端口数量的不同给出了9线制接法和改进的6线制接法;在单片机的I／O端口特别紧张的情况下,则可以采用串行接口电路。设计了双积分A／D转换器ICL7135与单片机的几种接口电路,具有简单可行,有效灵活的特点。为从事单片机设计和智能仪表开发研制的人员提供了一定的参考。     

使用A／D、D／A转换器必须考虑的问题

论述了数模、模数接口系统设计的要求，以及在接口系统设计中使用A／D、D／A转换器必须考虑的一些问题。     

高性能卡拉OK变调IC──TW9301

TW9301是单通道变调处理大规模集成电路，其变调范围可从－1800音分至＋1200音分，IC内有用于变调的A／D、D／A转换器和数据RAM。该IC最适合用作卡拉OK变调器，除此之外，还可以用于磁带录音机、电话机、玩具、音响、VTR等。其主要特点如下：·变调步长为100音分，即半个音·片内置有14比特浮点A／D和D／A转换器·内部信号处理的采样频率为16kHz·A／D、D／A转换的采样频率为32kHz·主时钟频率为768kHz（48fs）·可有三种方式控制变调：模拟电压方式；开关脉冲方式；微处理器脉冲方式·＋5V单电源，CMOS电路，封装形式有16脚D…     

D＼A转换器的应用

计算机的输出信号是数字信号,而有的控制原件或执行机构要求提供模拟的输入电流或电压信号,这就需要将计算机输出的数字量转化为模拟量,这个过程的实现由模拟量的输出通道来完成。输出通道的核心部件是数＼模转换器。D＼A转换器的作用是将数字量转化为相应的模拟量。通过研究D＼A转换器的工作原理以及主要的技术指标,以典型D＼A转换器芯片DAC0832为主要研究对象,进而探究D＼A转换器的应用——波形发生器。了解其工作原理以及波形发生所需要的程序。     

机载设备供电电源检测系统的设计

该机载设备供电电源检测系统的信号采集部分由单片机89C51、A／D转换器、电压和电流互感器以及相应的信号调理电路组成，硬件结构紧凑；上位计算机软件采用虚拟仪器软件LabWindows／CVI6．0开发，通过串口通信实现了对电源参数的实时采集和监控，软件功能强大且人机界面友好。该系统实现了飞机检修过程中电源的动态检测和故障定位，具有检测实时、故障诊断准确等特点。     

数据采集系统中A/D转换器的正确选择

A/D转换器是数据采集系统的核心器件,它的技术指标直接影响整个采集系统的精度.本文详细地介绍了A/D转换器的采样率、分辨率和精度三个技术指标,为用户正确选择A/转换器并建立数据采集系统提供参考.     

对《CD机中运放IC的选用》的异议

作为《音响技术》的忠实读者，我十分关心它的每一期，甚至每一篇文章的内容。这次读了95年第4期的（CD机中运放IC的选用）一文，对几个概念性的问题我有不同看法。干是，我写出来与大家商榷。第一．原文提出，"本人的CD机模拟线路是；I／V变换经二阶无源RC低通滤波器输出。D／A转换器是LC7881。"原文虽没有给出电路图．但我从使用该D／A转换器的众多CD机线路中（如爱特DP－906HR、爱特CD2208HR、镇江江奎电子公司生产的JK－2311等）．发现LC7881并非电流输出型D／A转换器，而是电压输出型。I／V转换由LC7881内部的运放完成…     

高精度A/D转换器AD7711及其在温场测试系统中的应用

本文介绍了24位A／D转换器AD7711的主要特点、结构和工作原理，以及AD7711在温场测试系统数据采集器中的应用。     

杆系结构三维模型图自动生成的算法与应用

利用AutoCAD提供的DXF数据交换功能,提出了一种新的生成算法,将空间斜杆一次性生成,直接读取空间杆系结构的有限元分析数据或优化设计数据,自动生成其三维模型图。文末给出了该算法在空间塔式起重机和空间网架、网壳造型中的应用。     

基于阶跃温度响应的热电偶时间常数测试系统

为了更方便地测试热电偶时间常数,设计了一套热电偶时间常数测试系统,包括工控机、信号调理电路、A/D采集、数据采集处理软件和打印机等。根据热电偶对阶跃温度的响应,提出了一种全新的热电偶时间常数测试方法,设计功能完善的信号调理电路,通过PCL818L数据采集卡将采集的数据送交上位机应用软件进行分析处理,得到所需要的热电偶参数,应用软件提供各类报表输出及数据打印功能。     

测量条件对A/D动态有效位数评价的影响

针对正弦拟合法评价A/D动态有效位数时测量条件对动态有效位数评价带来的误差影响,进行了拟合误差界的搜索研究.选取的条件变量分别是A/D位数、幅度、序列所含波形的周波数、初始相位、直流分量以及序列数据点数.以两两联动的双条件组合方式进行误差界搜索,获得了动态有效位数评价的误差界随不同条件变化而变化的曲线规律,筛分出了显著...     

An Ultrasensitive Silicon Photonic Ion Sensor Enabled by 2D Plasmonic Molybdenum Oxide

Silicon photonics has demonstrated great potential in ultrasensitive biochemical sensing. However, it is challenging for such sensors to detect small ions which are also of great importance in many biochemical processes. A silicon photonic ion sensor enabled by an ionic dopant–driven plasmonic material is introduced here. The sensor consists of a microring resonator (MRR) coupled with a 2D restacked layer of near‐infrared plasmonic molybdenum oxide. When the 2D plasmonic layer interacts with ions from the environment, a strong change in the refractive index results in a shift in the MRR resonance wavelength and simultaneously the alteration of plasmonic absorption leads to the modulation of MRR transmission power, hence generating dual sensing outputs which is unique to other optical ion sensors. Proof‐of‐concept via a pH sensing model is demonstrated, showing up to 7 orders improvement in sensitivity per unit area across the range from 1 to 13 compared to those of other optical pH sensors. This platform offers the unique potential for ultrasensitive and robust measurement of changes in ionic environment, generating new modalities for on‐chip chemical sensors in the micro/nanoscale.     

超声衰减增益补偿电路的设计

医用超声仪器发出的超声波在人体内的传播过程中，能量被人体组织吸收，随着探测深度的增加，超声波能量逐渐衰减，回波信号的动态范围很大，因此要进行声程补偿。文章简要介绍了超声诊断仪器的深度时间增益补偿电路(TGC)的基本原理，即用一定的电压曲线来控制放大器的增益，使不同深度下的超声回波获得不同的放大倍数。文中还提出了一种采用新型电子元器件的数字控制解决方案，能有效减小送入A／D转换器的信号的动态范围。该方案采用新型的高精度、低噪声、增益可变放大器AD604，电路简单，控制信号稳定可靠，能准确地补偿超声波在人体内的衰减，并为控制系统实现高速数字化提供了一个方法。     

Using 0/1 mixed integer linear programming to solve a reliability-centered problem of power plant preventive maintenance scheduling

The problem of power plant preventive maintenance scheduling is studied in this paper. A reliability perspective is considered. This problem consists of ascertaining which generating units must halt production to be examined regularly for safety. It is very important because a failure in a power station may cause a general breakdown in an electric network. The main consequence is that the electricity demand of customers will not be satisfied in such cases. Therefore, reliability is the key point used in the methodology presented. The problem is approached under the operations research perspective as an optimization issue. 0/1 mixed integer linear programming is used to solve the model reached. An application study is included. The model is put to use in a real power plant setting, representative of the Spanish one. The result obtained is a schedule that allows the efficient organization of preventive maintenance over a specific time horizon.     

Analysis of mismatch effects among A/D converters in atime-interleaved waveform digitizer

High-speed A/D conversion can be achieved by employing a parallel array of M A/D converters interleaved in time, each working at 1/Mth of the sampling rate. Theoretically, the resolution of the structure is given by the resolution of the A/D converters in the array (subconverters). In practice, however, mismatches among the subconverters lead to a decrease in the resolution. The effect of such mismatches is analyzed in terms of a signal-to-noise ratio defined as the ratio between the energy of the input analog signal and the energy of the error signal due exclusively to these mismatches. The analysis shows that the distortion is comparable to that generated by nonuniform sample timing in the analog demultiplexer when converting a single high-speed signal into several low-speed sampled-and-held signals. The results of the analysis can be used to specify the degree of precision to be achieved in an actual monolithic implementation     

Built-in self-test design of current-mode algorithmicanalog-to-digital converters

Analog MOS circuits are becoming increasingly sophisticated in terms of checking and correcting themselves. Self-correcting, self-compensating, or self-calibrating techniques has been employed in analog-to-digital (A/D) converters to eliminate errors caused by offset and low frequency noise, and to cancel the error effect. However, the self-compensating/calibration techniques may no longer work properly in the presence of faulty switching elements. This paper presents the fault behaviors and test generation of a current-mode algorithmic A/D converter, where the single stuck-at faults in the switching elements of the converter are assumes. The converter requires only two test currents to achieve a full testability. Due to the simplicity of generating test currents and the expected outputs, a simple built-in self-test (BIST) structure is proposed. Two extra pins for test enable signal and error indicator are needed. Results show that the full self-testability of the BIST structure is achieved with a low pin/hardware overhead, and the use of expensive test equipment is not necessary     

A greatest common divisor approach to blind super-resolution reconstruction of images

An algorithm for blind super-resolution reconstruction of a single image from multiple degraded observations is developed. The algorithm depends on estimating the 2D greatest common divisor (GCD) between each observation and a combinational image generated by a weighted averaging process of the available observations. The purpose of generating this combinational image is to obtain a new image with a higher signal to noise ratio, and a blurring operator that is co-prime with all the blurring operators of the available observations. The 2D GCD is then estimated between the new image and each observation and thus the effect of noise on the estimation process is reduced. The results of each 2D GCD process are fused to form a single reconstructed image, which is then interpolated subject to local regularization to form a high-resolution (HR) image. Results show that the proposed algorithm succeeds in estimating an HR image from noisy blurred observations in the case of relatively co-prime unknown blurring operators.     

石膏的直写成型：可打印石膏浆料的研制

石膏是雕像、建筑和铸造模具(合金和陶瓷)的常用材料。采用直写成型(Direct Ink Writing, DIW)打印石膏可避免其他3D打印技术(如Binder Jetting, PBBJ等)中存在水化反应不充分等问题, 获得高强度3D打印石膏。为了延缓水化反应获得充足的打印操作时间, 本研究通过添加缓凝剂和增稠剂, 研制了一种适用于直写成型的石膏浆料, 并打印了多种石膏三维结构(如蜘蛛网和木材堆积结构等)。结果表明, 质量分数为0.6%柠檬酸(Citric Acid, CA)的缓凝效果最好, 极大地减少了石膏流动性的经时损失。质量分数为0.3%羟丙基甲基纤维素(Hydroxypropyl Methylcellulose, HPMC)的增稠效果最好, 使石膏浆料具有良好的打印性能。CA的选择性吸附使得石膏晶体定向生长, 延长水化反应时间, 但一定程度降低石膏强度。HPMC加速石膏浆料中絮凝结构形成, 导致其粘度和剪切弹性模量升高。直写成型3D石膏件的抗压强度约为20 MPa, 远高于PBBJ等方法制备的石膏件的抗压强度。