MEMS矢量水听器的温度特性及其补偿方法研究

文中以MEMS矢量水听器为研究对象,分析其温度特性,采用BP神经网络方法进行温度补偿。海水的温度范围为-2~30℃,在该范围内对水听器的温度特性进行测试。测试结果表明:随着温度的变化,MEMS矢量水听器产生温度漂移,使其灵敏度发生浮动,这样严重制约了水听器的测量精度和应用范围。采用BP神经网络算法对水听器进行温度补偿,将水听器测量电压值和实时温度进行数据融合,削弱了环境温度的影响。补偿后,水听器的温度漂移显著降低,不同工作温度下的灵敏度曲线高度重合,灵敏度浮动不超过2 d B。     

基于温度补偿的甲烷检测系统设计与实现

由于现场农田环境的复杂多变性,红外甲烷传感器所测数据的准确性和稳定性受外界环境温度影响较大,因而由温度造成的浓度测量偏差需要补偿。分析温度对浓度测量的影响,采用温度、浓度控制单一变量法,对同一浓度甲烷标准气体在不同温度下作标定实验,研究红外甲烷传感器输出值随温度变化关系,得到补偿温度影响率,结合补偿数据处理算法得到补偿值。针对不同浓度的甲烷气体,进行温度特性实验和温度补偿数据处理,实验结果表明:温度补偿前最大测量误差为0.2%,经补偿后,甲烷浓度测量值随温度变化较小,误差范围为0~0.02%。补偿后传感器稳定性和准确性得到改善,能检测0~5%浓度甲烷气体,检测精度可达40×10-6,满足对CH4气体实时监测需求。     

基于环境温度反馈的卡塞格林望远镜自动调焦

为了在望远镜设备探测过程中实时调节由环境温度变化引起的光学系统组合焦距偏离,建立了温度与成像焦点位置调节的对应关系。通过理论计算得出卡塞格林望远镜系统组合焦距变化与温度变化的关系,利用步入式可编程高低温箱设计了温度实验,得出系统单位温度焦点位置的变化量,并在实际工作环境下进行了二次标定,得出望远镜设备的离焦量为-0.14 mm/℃。最后,结合理论实验设计了一种基于环境温度反馈的望远镜自动调焦装置,应用于设备外场观测实验,得出自动调焦装置使用前后望远镜系统的成像信噪比。实验结果表明,离焦量与温度变化量具有相关性,调焦装置使用后所成图像的均方根误差由5.056降低为0.729,成像信噪比由41.09提高到49.50。环境温度反馈的自动调焦技术有利于望远镜设备更好地捕捉观测目标,抑制背景噪声,提高信号采集的精确度与参数测量的准确度,增强了外场探测对环境温度变化的适应能力。     

压阻式压力传感器温度误差的数字补偿技术

压力传感器性能易受温度变化的影响,产生零点温度漂移和灵敏度温度漂移,从而增加了测量结果的误差.根据压阻式压力传感器温度误差分析,提出了基于MAX1457芯片的数字补偿技术,对温度误差进行补偿,并运用到多个压阻式压力传感器上,在特定的温度允许下进行补偿.结果表明该种方法补偿精度高、稳定性好,有效地抑制了温度漂移.     

基于ATmega16的压力传感器温度补偿智能化设计

针对硅压阻式压力传感器的温度漂移现象,提出了一种压力传感器温度补偿智能化的设计方法。该设计以ATm ega16为核心芯片,以CS5532为模数转换器,整个电路选用低温漂的元件,并且在软件补偿中采用二次曲面法。实验温度范围为-30~55℃,经过反复实验,得出智能传感器在不同温度下最大测量误差为0.29%的结论。实验结果表明:此智能化的设计可以很好地补偿压力传感器的温度漂移,提高传感器的性能及测量准确度。     

常温下硅微谐振加速度计零偏稳定性的提高

考虑环境温度会影响硅微谐振加速度计(MSRA)的测量精度,本文研究了谐振梁的频率漂移及抑制方法以便提高其在常温下的零偏稳定性。针对结构热膨胀导致的应力进行了建模仿真,并根据仿真结果优化设计了一种低热应力的双端固支梁的结构来降低热膨胀系数不匹配带来的频率漂移。实验测得新结构的单梁谐振频率的温度系数从典型结构的约30Hz/℃降为-1.5Hz/℃,与仿真结果-1.14Hz/℃基本一致。为了进一步提高该加速度计的零偏稳定性,设计了一种高精度测温电路用来补偿温漂,该电路测温灵敏度为96.25mV/℃,测量噪声约为0.000 2℃。实验结果表明,采用优化后的结构结合线性温度补偿的方法,可使该硅微谐振加速度计的1h零偏稳定性在常温下达到10μg以下,比改进前实验室获得的52μg水平提升了80%,满足了高精度加速度测量的要求。     

基于BP神经网络的霍尔式金属浮子流量计温度补偿方法

在恒温实验装置上,对霍尔式金属浮子流量计的温度漂移进行了实验研究.研究了温度对金属浮子流量计的敏感元件(霍尔元件)的影响.在实验的基础上,提出一种基于BP神经网络的霍尔式金属浮子流量计温度补偿算法,并与多项式的拟合结果进行对比.通过仿真比较,证明该方法具有较高的补偿精度,适合于补偿环境温度对霍尔式金属浮子流量计的影响.     

液压缸行程测量系统的零点漂移补偿

在以活塞杆为标尺的液压缸行程测量实验中发现,受传动间隙、活塞杆表面加工质量及环境温度等因素的影响,测量系统的输入信号常伴有零点漂移。这导致细分辨向电路输出脉冲间隔发生变化,影响测量结果准确性。本文提出了使用数字式零漂补偿技术,采用递推平均滤波算法与极值平均算法对零漂信号进行纠正。同时使用单片机PIC16F876对该算法予以实现。     

基于32位∑-ΔADC的高精度测温系统设计及误差分析

为了满足反应量热仪中对样品温度的高精度检测要求,以32位∑-Δ型模数转换器AD7177-2为核心,设计了基于阻值比较法的铂电阻高精度测温系统,采用电流激励换向技术,消除电路中存在的寄生热电动势及系统漂移对测量的影响;提出了基于阻值标定的共模误差修正方法,提高了测温准确性。实验结果表明:系统在-100～500℃范围内,修正后的测温误差由0.28℃减小至0.01℃,不同环境下的测温精密度优于±0.001℃,满足反应量热仪的测温精度需求。     

图像式路基沉降监测系统的温度补偿方法

为减小图像式路基沉降监测系统中温度变化对测量结果的影响,通过对其核心设备—CMOS 工业相机的温度漂移进行 研究,提出一种针对该监测系统的温度补偿方法。 首先,分析说明了温度变化会对监测系统测量精度造成影响;然后,建立漂移 参数补偿模型并设置实验进行验证。 漂移参数补偿模型使相机的像点误差从 1. 0~ 2. 5 pixel 降低到 0. 1~ 0. 4 pixel,验证了该模 型的正确性;同时设置对比实验,与系统辨识的方法相比,两种方案补偿效果接近,但提出的补偿方法过程简单,更具实用性;最 后,提出路基沉降监测系统的温度补偿方法并验证。 结果表明,该方法能够提高监测系统测量精度。 所提补偿方法,对于提高 图像式路基沉降监测系统的测量精度具有重要意义。     

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.     

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....     

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。     

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.