智能酸度转换器的设计

设计一种智能型酸度测试仪表(简称pH计).具体介绍了酸度计的设计原理及硬件构成.转换器采用高阻差动放大电路测量酸度电极信号,单片机内核作实时处理,液晶数码管显示.同时印刷电路板上加绝缘环以消除线路板绝缘电阻对放大电路输入阻抗的影响,通过软件校正电极偏差,并具有上下限报警功能.仪表具有体积小、可靠性高、测量精度高,便于现场使用、操作性好等特点,因此具有很大的经济和实用价值.     

基于PIC单片机的pH测试仪

设计了一种酸碱浓度(pH)测试仪,介绍了测量仪的设计原理、硬件电路及软件设计.选用高精度差动放大器INA116放大复合电极输出的微弱电压信号、抑制现场干扰及复合电极的高内阻影响.为满足测量精度,对温度信号进行了有效补偿并通过软件校正电极偏差.PIC单片机进行实时处理.测试仪具有两点标定、自动温度补偿等功能.测试结果表明:测试仪能准确地测量溶液的pH值,满足设计要求.具有精度高、稳定性好、操作便捷等优点,应用前景广阔.     

一种铂电阻温度传感器的优化设计

基于航天工业中温度信号的测量,研制了一种高测量精度的铂电阻温度传感器。设计采用恒流源微电流驱动三线制铂电阻经不平衡电桥获得理想电压,实现了去除自身线阻和减小自热效应;提高了测量精度。通过差分放大电路、反馈电路和压控电压源二阶低通滤波电路有效地改善了铂电阻的线性度,减小外界干扰信号对测量系统的影响。测量结果表明,在-40~60℃的变温环境中测量-20~450℃温度误差小于0.5℃。     

差动结构电涡流式液位传感器性能改进与应用

为满足超薄快速铸轧机对熔铝液位精确测量的要求 ,对原有的用于钢水液位检测的差动结构电涡流式液位传感器进行了改进。传感器为发射接受式 ,1个发射线圈 ,两个接受线圈。由于采用差动结构 ,减小了环境、温度等因素对系统的影响 ,前置电路中核心部分采用反馈放大电路。通过对前置电路关键参数进行优化 ,提高了传感器示值稳定度 ;采用曲线拟合法处理输出信号提高了传感器的测量精度。测量结果表明 ,改进后的差动结构电涡流传感器在 89mm量程范围内精度达到± 0 .12mm ,稳定度为 0 .5 2 %。     

在线黏度测量中的温度特性研究及其补偿

对一类智能应变黏度传感器的工作原理进行了阐述,解析了影响该传感器温度特性的因素.系统基于温度补偿和差分放大电路的集成实现传感器零漂温度校正,采用DS18B20-PAR单总线温度传感器进行温度测量和基于BP算法的神经网络进行温度补偿和校正,使得黏度传感器的输出信号为测量信号的单值函数,消除了温度的影响,试验结果证实提高了测量精度.     

激光调阻机多档测量误差的软件自适应校正

为了减小激光调阻机测量系统的多档测量误差对阻值修调精度的影响,提出了一种基于有源单臂电桥测量原理自适应地校正激光调阻机多档测量误差的方法.通过测量和标定高精度标准电阻的测量误差,自适应地获取校正激光调阻机多档测量误差的系列修正值,进而用系列修正值对所有待修调电阻的阻值测量误差进行校正,达到进一步减小系统测量误差的目的.实践证明,在测量硬件电路保证高稳定性、微小波动性测量的前提下,应用该方法可使测量系统的精度指标达到:低阻区(R<100Ω)为±0.5‰;中阻区为±0.2‰;高阻区(R≥1MΩ)为±2‰.     

高精度铂电阻测温仪的设计与实现

提出了基于四线制恒流源驱动和恒流换向技术的高精度温度测量方案,挑选性能优异的铂电阻Pt100作为温度传感器,与参考电阻串联后由恒流源驱动,然后采集信号经过调理放大,通过单片机自动校正和控制,并内嵌ITS-90国际温标计算公式,以此实现高精度温度测量。实验结果表明,该方案较好实现了消除引线电阻和非线性的影响,提高了测量精度,温度测量误差小于0．01℃。系统性能稳定。     

基于RBF神经网络的湿度传感器建模方法

针对高分子湿度传感器的测量精度易受温度影响的问题，提出了湿度硬件测量电路，建立了高分子湿度传感器的数学模型。此硬件测量电路的湿度传感器选用IH3605，温度传感器选用AD590。此数学模型采用RBF神经网络，利用在线测量的温湿度信号值，应用带遗忘因子的梯度下降算法进行网络参数的调整，同时给出了建模步骤。实际结果表明，该模型的误差小于0．5％RH，具有较高的精度。     

基于K型热电偶数据拟合的温度测量系统设计

针对K型热电偶测温的特性结合虚拟仪器技术,本文设计了一种具有高精度的温度测量系统。利用温度传感器AD592完成K型热电偶冷端自动补偿,仪用放大器完成对热电偶输出信号进行放大以满足数据采集卡对输入信号的要求,同时采用LabVIEW软件完成曲线拟合。测试结果表明,系统具有测量精度高、可靠性高、使用灵活等特点,当被测温度范围在10～180℃之间,测量的绝对误差小于±0.5℃,可广泛使用于要求较高精度温度测量的领域。     

电容式位移传感器转换电路的设计

介绍一种用于动平衡分析仪差动电容式位移传感器信号转移电路。利用差动测量技术，将电振动引起的微小电容变化量转化成交流电压信号。电路由差动放大电路、正弦信号发生器、模拟乘法器和二阶低通滤波器组成，该电路线路简单、集成度高、便于调试。通过电压转换电路可以将－10～＋10V的输出电压转变成为0～5V的电压，便于带有A／D转化电路的单片机系统直接进行A／D转换，简化了电路设计。实验表明该转换电路具有较好的线性和抗干扰性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.