一种压力传感器的频率输出转换接口电路

本文叙述了一种压力传感器的频率输出转换接口电路的特点、组成和工作原理以及调试过程。     

传感器输出信号的线性化处理

在检测装置的组成环节中,往往存在非线性环节,特别是传感器的输出量与被测物理量之间的关系,绝大部分是非线性的.造成非线性的原因主要有二:一是许多传感器的转换原理并非线性,如温度测量,热电阻或热电偶与温度是非线性关系;流量测量,孔板输出的差压信号与流量输入信号之间也是非线性关系;二是采用的测量电路的非线性,例如,测量热电阻用四臂电桥,电阻的变化引起电桥失去平衡,出现的输出电压与电阻之间的关系为非线性.对于这类问题的解决,常规模拟仪表采用的非线性补偿方法,都需要增加若干硬件,如用特别的曲线板,利用二极管、各种集成运算放大器构成非线性补偿电路,采用非线性计数的数字化电路和采用连续线性化A/D转换器等.这些硬件补偿,不但成本高、电路复杂.调试困难,而且精度低、通用性差.在智能仪表中,线性化采用软件方法实现,不必增加特殊的硬件结构,其主要优点有:①充分     

基于ARM的数据采集系统硬件部分实现

本文详细的阐述了基于ARM处理器的数据采集系统硬件部分的设计与实现.整个硬件电路分成两个部分:主控电路部分和数据采集部分.在主控电路部分,我们完成了主芯片设计、存储器电路、串口电路、网络电路的设计.在数据采集部分,我们完成了信号调理电路、滤波器电路、A/D转换电路、D/A转换电路的设计.最后给出了系统硬件调试方法.     

大电路固定极性Reed-Muller逻辑快速转换算法

针对已有的列表技术在极性转换中只能解决中小规模电路的问题,提出一种基于不相交乘积项列表技术的快速转换算法.首先将待处理的逻辑函数表示为不相交乘积项之和形式;然后通过对已有的基于最大项的列表技术进行分析和改进,使得改进后的列表技术可以实现将逻辑函数从不相交乘积项的AND?OR形式向固定极性XNOR?OR形式的Reed-Muller逻辑转化.文中算法用C编程实现,并用MCNC标准电路进行测试.实验结果表明,该算法可以快速实现大电路的极性转换,并且具有运算速度对电路的输入变量数不敏感的特点.     

使用系数矩阵变换极性转换的MPRM电路面积优化

为缩短布尔函数系统混合极性Reed-Muller(mixed-polarity Reed-Muller,MPRM)电路面积优化过程的时间,提出了能在任意极性值的MPRM间进行极性转换的系数矩阵变换方法.使用系数矩阵表示布尔函数系统,通过对系数矩阵进行分隔,使用置换和折叠操作完成MPRM极性转换以加快极性转换速度;在此基础上,给出了适用于较大规模MPRM电路的面积优化算法,其中使用遗传算法进行极性空间搜索,并采用基于最短个体距离的适应度计算方法进一步缩短优化过程中的极性转换时间.实验结果表明,与其他MPRM极性转换方法相比,文中方法能够提高MPRM电路面积优化的速度.     

一种高精度可燃气体检测报警器设计

利用半导体可燃气体传感器MQ-2设计了一种可燃性气体体积分数检测报警器,由可燃性气体传感器、模/数转换电路、单片机、显示电路、声光报警电路等组成.传感器MQ-2将气体体积分数转换为电压信号,送A/D转换电路,转换后的信号送STC89C52单片机,单片机经过处理后控制显示单元显示气体体积分数,同时控制驱动报警电路实现声光报警.实验表明:该检测报警器对异丁烷、甲烷、天然气等可燃性气体检测精度达到了0.01％,具有检测性能稳定、线性度好、电路简单、成本低、小型化、便于调试等特点.     

数字测温电路的差值灵敏度的设计分析

通过对铂温度传感器的测温电路的大量实验和分析研究,提出了数字测温电路中,A/D转换电路差值灵敏度的概念,分析了铂电阻温度电压放大曲线的斜率的线性特点和调试方法,以及数字显示测温电路A/D转换差值灵敏度的测试.研究表明,使铂电阻温度电压放大曲线的斜率值等于A/D转换电路的差值灵敏度,是提高测温电路精度的关键问题,并分析计算了调整斜率的理论根据和具体方法,讨论了数字测温电路中产生测量误差的因素以及提高精度的其他措施.     

基于整体退火遗传算法的低功耗最佳极性搜索

针对n变量逻辑函数在不同极性下所对应的XNOR/OR电路功耗和面积不同的特点,首先用信号概率传递算法和多输入XNOR/OR(同或/或)门的低功耗分解算法建立了XNOR/OR电路的功耗估计模型.在此基础上,将基于列表技术的极性转换算法和整体退火遗传算法相结合,提出了一种针对大规模XNOR/OR电路的低功耗最佳极性搜索算法.对8个较大规模MCNC Benchmark电路测试表明,该算法搜索到的最佳极性所对应的XNOR/OR电路与极性0时的XNOR/OR电路相比,平均节省功耗和面积分别达到了84.4%和65.2%.     

Proteus软件在实践教学中的应用

分析了Proteus软件在实践教学中的可行性和优越性,结合教学实例论述了硬件设计、程序编制及仿真调试的全过程,给出了仿真调试、电路原理图、C51源程序等具有一定实用参考价值的资料。     

高精度加速度传感器信号处理电路的设计

介绍了一种基于AD650的高精度加速度传感器的V/F信号处理电路的设计.通过电压/频率变换的方式来实现A/D变换,使得输入/输出的转换速度和转换精度的调节具有较大的动态范围.AD650作为一种高精度的电压/频率转换器件,其外围电路设计简单,通过适当的电路设计与调试,可以获得4.92×10-4的非线性度和小于0.01Hz/min的零偏稳定性.     

基于CPS-SPWM调制方式的链式STATCOM研究

针对非线性、冲击性负荷给煤矿电网注入了大量无功功率和谐波的问题,研究了基于CPS-SPWM调制方式的链式静止同步补偿器STATCOM;介绍了链式STATCOM主电路结构;针对链式STATCOM调制方式包括单极性CPS-SPWM和双极性CPS-SPWM两种调制方式,采用Matlab仿真分析了基于H桥基本模块和基于级联H桥的单极性CPS-SPWM调制方式与双极性CPS-SPWM调制方式的差别,结果表明,单极性CPS-SPWM调制方式的波形质量明显好于双极性CPS-SPWM调制方式,链式STATCOM应选用单极性CPS-SPWM调制方式;采用Matlab/Simulink平台对不同调制比下的基于单极性CPS-SPWM调制方式的链式STATCOM进行仿真,结果表明,该链式STATCOM具有输出波形好、谐波低、扩展性强等特点。     

Weight decay and resolution effects in feedforward artificialneural networks

Results are presented from a preliminary study on the effects of weight decay and resolution on the performance of typical three-layer, feedforward neural networks. Two types of decay are investigated, unilateral decay toward the most negative weight (unipolar) and bilateral decay toward the median or zero weight value (bipolar), and compared with Gaussian weight perturbations. This analysis is pertinent to the area of VLSI-based network implementations with analog weight storage. The results show that, if weight decay is unavoidable, bipolar decay achieves an order-of-magnitude better performance than unipolar and that the weight resolution required in actual implementations of feedforward, connectionist hardware is higher than predicted by computer simulations of network responses to random or Gaussian weight perturbations.     

ADuC847的一类高精度I/F转换器的设计

设计了基于ADuC847的一类高精度、高输出的I/F转换器。首先,将双极性电流信号转换为双极性差分电压信号;然后ADuC847对该双极性差分电压信号进行A/D采样,通过对采样信号进行数字滤波,获得较稳定的A/D值。接着对零点和满量程进行校正;最后通过数字频率合成算法,由PWM0输出频率信号,而频率的双极性则由74LS00实现。     

双极信息的聚合与分解

信息聚合是信息处理过程中的基本手段,主要讨论若干聚合算子的性态。首先,从广义伴随对的角度讨论了广义聚合算子的性质。从聚合算子 A 出发,给出两种不同的方法,构造了大于(小于)等于 A 的新的聚合算子;其次,对于处理双极信息用到的聚合算子、双极t-模和双极蕴涵做了讨论,得出了这两个双极聚合算子可分解为两个单级聚合算子的条件。在此条件下即清晰可见聚合双极信息时对正信息及负信息的聚合过程。这对提取特定信息具有极其重要的意义。     

基于双极偏好控制的多目标粒子群优化算法

考虑双极偏好信息对粒子群的控制作用,提出一种使用双极偏好——正偏好和负偏好引导粒子群向 Pareto 前沿偏好区域进化的方法．根据TOPSIS 决策法思想,将外部种群粒子与正负偏好点的相对贴近度排序作为 外部种群管理和全局最优解更新策略;根据贴近度值确定解集的分布度;选取6 种不同类型的多目标测试函数进行 算法模拟,从世代距离、空间测度和超体积测度3 个指标与基于单极偏好的多目标粒子算法进行性能比较．结果显 示,基于双极偏好控制的多目标粒子群算法的收敛性和综合性能更优秀．     

一种新颖的Π型双极性D/A转换器的设计

在分析通用双极性输出D/A转换器的基础上,给出了Π型电阻网络单元及串联电阻计算方法,提出了一种全新的Π型双极性输出D/A转换器,该电阻网络电阻个数少、阻值选取方便,有重要的理论及应用价值。     

Wafer-level testing with a membrane probe

The authors describe a proprietary membrane probe card that addresses the needs of testing VLSI devices at the wafer level. The membrane probe allows the testing of devices with a high pin count at operating speed, while allowing a complete package test at the wafer level. The concepts and structure of the probe are examined, and its performance is demonstrated by time-domain and frequency-domain measurements of the typical electrical characteristics of a VLSI digital probe that accesses 272 pads at a pitch of 110 μm. Applications to a bipolar ECL (emitter-coupled logic) flash A/D (analog-to-digital) converter, a bipolar ECL D/A converter, an application-specific CMOS IC, an NMOS VLSI central processing unit, and area-array solder bumps are presented     

An integrated optical position-sensitive detector with digital output and error correction

An integrated optical position-sensitive detector (PSD) with digital output is presented. A novel interpolating analog-to-digital converter which is based on a sigma-delta converter, is applied to perform three operations simultaneously. These are: calculation of the relative position cancellation of errors, both optical and electrical; generation of a microprocessor-compatible digital output. The realized smart sensor is integrated in a standard bipolar IC process, and measures 6.5 mm × 2.5 mm.     

Artificial intelligence approach to classify unipolar and bipolar depressive disorders

Machine learning approaches for medical decision-making processes are valuable when both high classification accuracy and less feature requirements are satisfied. Artificial neural networks (ANNs) successfully meet the first goal with its adaptive engine, while nature-inspired algorithms are focusing on the feature selection (FS) process in order to eliminate less informative and less discriminant features. Besides engineering applications of ANN and FS algorithms, medical informatics is another emerging field using similar methods for medical data processing. Classification of psychiatric disorders is one of the major focus of medical informatics using artificial intelligence approaches. Being one of the most debilitating psychiatric diseases, bipolar disorder (BD) is frequently misdiagnosed as unipolar disorder (UD), leading to suboptimal treatment and poor outcomes. Thus, discriminating UD and BD at earlier stages of illness could therefore help to facilitate efficient and specific treatment. The use of quantitative electroencephalography (EEG) cordance as a biomarker has greatly enhanced the clinical utility of EEG in psychiatric and neurological subjects. In this context, the paper puts forward a study using two-step hybridized methodology: particle swarm optimization (PSO) algorithm for FS process and ANN for training process. The noteworthy performance of ANN–PSO approach stated that it is possible to discriminate 31 bipolar and 58 unipolar subjects using selected features from alpha and theta frequency bands with 89.89 % overall classification accuracy.     

An application of PSO technique for harmonic elimination in a PWM inverter

Harmonic elimination problem in PWM inverter is treated as an optimization problem and solved using particle swarm optimization (PSO) technique. The derived equation for computation of total harmonic distortion (THD) of the output voltage of PWM inverter is used as the objective function in the PSO algorithm. The objective function is minimized to contribute the minimum THD in the voltage waveform and the corresponding switching angles are computed. The method is applied to investigate the switching patterns of both unipolar and bipolar case. While minimizing the objective function, the individual selected harmonics like 5th, 7th, 11th and 13th can be controlled within the allowable limits by incorporating the constraints in the PSO algorithm. The results of the unipolar case using five switching angles are compared with that of a recently reported work and it is observed that the proposed method is effective in reducing the voltage THD in a wide range of modulation index. The simulated results are also validated through suitable experiments.