浅析珠状热敏电阻在高空探空仪中的应用

在理解原型数字式珠状热敏电阻温度传感器电路设计思想的基础上,本文设计了满足高空探空仪需求的单项数字式珠状热敏电阻温度传感器电路,通过试验分析获取已选定的热敏电阻元件的传感特性数学公式及变换电路的变换特性数学公式,提出了单项数字式珠状热敏电阻温度传感器测温计算方法。     

用于光气动探测的微流量传感器

针对气体红外吸收的气动探测应用,设计了基于MEMS技术的Sandwich结构硅基微流量传感器.在1 mm2面积内制备了阻值约1.6 kΩ的蛇形Pt薄膜作为加热及测温电阻,其电阻-温度系数(TCR)约2.2×10-3/℃.Pt薄膜采用4 μm厚氮化硅悬梁作支撑,在125℃工作温度下功耗约44 mW.研究了Pt薄膜电阻对的间距以及工作温度对微流量传感器性能的影响,并将其用于CO2气体检测.在0～1 mL/min的测试范围内,该微流量传感器输出信号与气体流量成线性关系,理论检测下限约8.5 μL/min,可用于气体红外吸收的气动探测.     

探空温度传感器的太阳辐射误差修正方法研究

由于太阳辐射的影响,探空温度传感器高空测量时的辐射误差可达3 K量级。为提高传感器测量精度,提出一种太阳辐射误差修正方法。首先通过计算流体动力学(CFD)方法计算珠状热敏电阻的太阳辐射误差,然后采用准牛顿法(BFGS)拟合仿真数据并得到太阳辐射误差修正方程,最后通过低气压风洞和太阳模拟器实验平台对修正方程的准确性进行验证。实验结果表明,在太阳高度角和海拔高度范围分别为0°～60°和10～32 km时,珠状热敏电阻辐射误差修正值与实验测量值之间差值的平均值为0.124 K,均方根误差为0.083 K,验证了辐射误差修正方法的可行性。     

高精确度数字温度测控仪的研制

在众多测温系统中，测温元件通常选用热敏电阻、半导体测温二极管以及集成模拟温度传感器等。中间环节由低通滤波、多路切换、信号放大、模数转换等几部分组成。由于以上各类温度传感器及其他器件的互换性较差，温漂和非线性误差较大，因此，整个测温系统的测量误差也随之增大。同时，由于中间环节较多，系统的抗干扰性能也不理想，测量精确度相对较低。随着对环境的检测与控制的要求越来越高，以及各种精密技术(如纳米技术)的飞速发展，研发具有测量精确度高、使用简单、不易受环境干扰等特点的数字式温度传感器势在必行。     

基于GA-BP神经网络温度补偿的红外温度传感器设计

为减少环境温度对红外测温的影响,并提高测量精度,提出了一种基于热电堆与热敏电阻的红外探头、Cortex-M3 ARM处理器及高精度低噪声测量电路的红外温度传感器。利用梯度下降法建立红外探头的输出电压、环境温度和目标温度的BP神经网络模型,用遗传算法对其初始权值和阈值进行优化,并将基于该模型的算法嵌入ARM处理器,求出目标温度。该红外温度传感器实现了对物体温度-10～+50℃范围的测量,平均绝对误差为0.033℃,均方根误差为0.035℃。     

基于生物组织体内温度测量的微型点温仪设计

生物组织体内部温度测量是研究组织热损伤的关键技术,本文介绍一种基于微型热电偶的联机测温系统,该系统采用集成温度传感器AD590和数值计算进行热电偶冷端温度补偿,同时进行软件非线性校正,实现温度的采集、处理、显示和存储,便于温度实时监测、数据回放和分析。温度传感器采用K型铠装热电偶(ф0.5mm),测温范围为0-600℃,响应时间<0.3s,AD590灵敏度为1μA/K。采样频率可调,实验时采用10Hz的采样频率,实验结果显示在26-98℃范围内误差绝对值<0.7℃。该电路无需精确的线性和增益调节、结构简单、调节方便,适合于瞬间和长期温度跟踪,具有较高的稳定性和测量精度,是一种实用的温度跟踪、分析和联机系统。     

一种宽线性测温电路

本文介绍的宽线性测温电路系由积分振荡器与一对热敏电阻组合构成。它能在-45～+5°C,-5～+45℃温度区间线性工作,最佳线性度可优于0.02℃。该电路结构简单,调节方便,适用于水文、气象、医疗、粮仓等测温领域。     

基于光纤光栅的小热惯量温度场监测实验

为了研究温度传感器测量小热惯量温度场的准确性和即时性,对2ml沸水分别利用水银温度计、热电偶和金属管封装的光纤光栅温度传感器进行测温,所测温度的值分别为94.0℃、95.0℃和98.6℃,三者的响应时间分别为10.0s、8.5s、2.5s。可见,小体积金属管封装的光纤光栅温度传感器测量精度高,响应速度快。并对不同封装工艺的光纤光栅温度传感器的传感特性进行比较,结果表明,对于小热惯量温度场的监测,传感器的封装方式应采用小内径金属管封装方式。     

一种基于FX2N的NTC线性化设计

NTC热敏电阻具有灵敏度高、体积小等优点,广泛应用于各类温度测量场合,但由于其高度非线性,在实际应用中需要进行线性化处理。本文针对需要采用NTC热敏电阻测温的PLC控制系统,提出一种恒压源测温方案。分析并设计硬件方案,利用MATLAB离线分段拟合线性表达式,拟合曲线表明系统拟合度很高。文中根据拟合后的线性表达式,利用FX2N实现温度的测量,并在0℃～100℃范围内进行了标定校准,测温误差小于0.2℃。     

新型高温热敏电阻

研制稳定的高温热敏电阻是复杂的任务,其解决的难度随着热敏电阻工作温度增高的程度而增长。下面引证供在600～1000℃下工作之用的新型热敏电阻的数据。热敏电阻的结构系统示于图1。敏感元件用直径近于1mm装有铂电极3的半导体小珠2制成。电极3电焊到比较粗的(直径0.4mm)用耐热合金595制成的金属引线4上。由高频瓷制成的双通路的陶瓷管1作为热敏电阻的外壳,它的长度原则上可以在任何所需要的范围内变化。半导体小珠置于管子一端的槽或者孔     

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.     

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.