基于振弦式传感器的测频系统设计

为了满足大型结构安全监测中振弦式传感器的数据采集需求,提出了一种用等精度测频实现振弦式传感器频率测量的实用方法,并给出了具体的硬件电路,系统硬件分为3部分:激振电路、测振电路、温度补偿电路.应用AT89C52单片机实现等精度测频的原理、实用电路,具有测频范围宽和测量精度高等特点,且应用AT89C52单片机实现激振频率可控.测频系统具有硬件电路简单,激振可靠、激振频率可控,温度补偿可以减小温度对振弦式传感器频率测量的影响,提高测量精度.     

电导率仪的改进

本文介绍一种简便、实有的液体电导率微弱变化测量系统,该系统利用补偿比较的方法测量液体电导率的微弱变化,使其测量精度比现行国产电导率仪的测量精度提高３个数量级,从而解决了液体电导率微弱变化的测量问题。     

抛弃式海水电导率测量电路设计

介绍了一套基于单片机的海水电导率测量系统,是国内正在研究的抛弃式盐温深测量系统中的一部分.在硬件的设计实现过程中,采用了温度补偿、低温漂整流等技术来克服海水温度变化40 ℃对传感器和电路的影响.经实验证明,该系统测量海水电导率的精度达到±0.08 mS/cm.     

一种新型电容式电导率传感器的设计

为解决电导率传感器耐压能力差,难以在地下水、深水井、水库等环境下进行精确检测的问题,设计了一种新型电容式传感器。根据静电比拟原理,建立电导率-电容-压力-温度理论计算模型,并通过实验验证算法模型的准确性。实验结果表明,传感器结构耐压,可承受1.5 MPa的水压,重复性误差小于1%,测量精度在±1%的误差范围内,扩大了电导率传感器的量程范围和应用场合,适用于地下水、深水井等较大压力环境下的电导率测量。     

探空温湿压系统研制

介绍了用于测量大气湿度、温度和气压探空集成传感器系统.利用集成温湿压传感器采集信号,测量采用24位AD精度MCU,借助CC1000将信号调制,MAX2235将信号功率放大无线发送.给出了集成温湿压传感器结构、测量系统的原理、测量系统的硬件框图及关键软件的设计流程.实验结果证明该系统在满足测量精度的条件下,降低了系统的体积和成本.     

制药纯水电导率分析仪表校准

从相关法规对制药用水电导率分析仪器的要求入手,介绍了电导率传感器电极常数的验证和校准、电导率变送器（测量回路）的验证和校准、电导率分析仪器／仪表的系统校准验证。认为利用校准好的电导率标准测量系统、可追溯模拟阻抗器、校准好的标准电导率传感器进行的比对法电导率分析系统校准方式优势凸显,不失为更先进、精确可靠的电导率测量系统校准技术。     

基于电容传感器的数字式飞机燃油油量测量系统的设计

介绍了利用电容传感器测量飞机油箱内油量的原理,给出了基于电容式传感器数字式油量测量系统的详细设计方案,并从理论上定量地分析了该电容传感器主要测量误差,这对提高油量测量系统的测量精度提供了理论依据,阐述了系统软件设计思想.设计的电容传感器具有结构简单、使用方便、精度高等特点.     

高速高精度频率测量系统的CPLD实现

介绍了等精度测频原理,分析了测量误差.在一片CPLD上实现频率测量和数据处理,设计了宽范围、高集成度、高速、高精度和高可靠性的频率测量系统.     

两非正交传感器测量主轴回转精度的误差分离技术研究

提出非正交安置两传感器在线测量主轴回转精度的误差分离技术理论,可同时获得主轴回转误差和工件圆度误差的测量结果。本方法虽然存在原理误差,但具体实施时却有传感器安装调整容易、测试系统简单、成本低廉和便于测量等诸多优点。较现行三传感器法更具有实用性。同时讨论了实际测量保证误差分离精度注意的几个问题。     

纳米测量精度光栅传感器研究综述

概括分析了光栅纳米测量中双光栅测量系统、炫耀光栅测量系统、基于误差修正技术的光栅纳米测量系统、基于二次莫尔条纹原理的纳米光栅测量系统的测量原理。介绍了纳米测量精度光栅传感器研究的关键技术。     

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.     

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。     

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....     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.