静电悬浮转子微陀螺微位移信号检测系统的设计

为实现对悬浮转子微陀螺转子五自由度的测量,提出了一种频分复用的微位移检测原理,主要介绍了多频率信号发生器,前置放大器,锁相放大器组成的测试系统,设计了一种基于DDS技术的多频率信号发生器和基于锁相放大原理的解调电路。实验和分析结果表明,该电路能实现多自由度微位移检测,设计的多频率信号发生器的频率分辨率能达到0．005821Hz,相位分辨率可以达到0．006rad,检测轴向灵敏度为1．34V／μm,检测径向灵敏度为0．092V／μm,测量电路的轴向位移分辨率为0．45nm,径向位移分辨率为6．6nm,转角的分辨率为0．25μrad,位移检测电路的分辨率,灵敏度和测量范围能够满足静电悬浮转子微陀螺的控制需要。     

磁轴承用电涡流位移传感器串扰产生及抑制方法研究

针对磁悬浮控制力矩陀螺(CMG)对位移传感器的特殊性能指标要求,设计了一种五自由度电涡流位移传感器系统,将径向探头和测量电路进行了集成一体化设计,对探头之间串扰产生的原因进行了理论分析,并提出在原有振荡电路上增加调整电容,通过调节调整电容值提高探头之间串扰频率使其无法通过后续滤波的方法抑制串扰,提高了转子的位移检测精度。实验结果表明,实现了转子在0～30000r/min范围内的稳定悬浮,悬浮精度小于20μm,满足了磁悬浮CMG电磁轴承对转子位移高精度检测的需求。     

高精度位移传感器线性度标定方法研究

针对光学系统中光学元件的高精度位移调节和检测问题,提出一种非接触电容位移传感器的线性度标定方法,搭建了一个运动轴、测量轴和传感轴三轴共线的标定平台,从测量原理上消除阿贝误差。介绍了标定平台的组成和标定方法的原理,采用对称平行四边形机构实现微位移调节,基于柔度矩阵法分析了调节机构的输出柔度和行程。试验结果表明,机构的柔度为13.585μm/N,运动行程为543.4μm,分辨率约为10 nm。经过标定补偿计算,传感器的线性度由0.047 14%提高至0.004 84%。该线性度标定方法精度高,标定后的传感器满足精密位移调节机构使用要求。     

球面间隙大范围测量的建模与线性化研究

有源静电悬浮轴承通过检测电极与转子间构成的球面间隙电容以得到转子位移。在转子起支时，要能实现球面间隙的大范围线性测量，本文重点推导了球面电容与球面间隙的非线性关系，提出了采用软件非线性校正的方法实现球面间隙大规范测量的线性化，使转子位移的线性测量范围可以达到标称间隙的66％，满足了静电轴承起支过程的要求。     

高精度电容式位移传感器关键技术的研究

研制了一种高精度电容式位移传感器,详细介绍了该传感器的基本工作原理和提高传感器精度的关键技术,对电容传感器的具体电路进行模块化设计;分析影响传感器精度与稳定性的因素,采用完全等电位屏蔽技术,对正弦激励电路、参考电容、传感器测头、电源进行技术改进,最后对电容传感器进行系统标定。实验证明:该传感器测量范围为±5~±40μm,测量分辨率<10 nm,测量精度<20 nm.     

电容检测型微机械陀螺的信号检测电路

微弱输出信号的检测技术是微机械陀螺研制中的关键技术之一.提出了一种适用于电容检测型微机械陀螺的信号检测电路并分析了其对噪声的抑制能力.此电路用积分电路检测微小电容变化量,并进一步采用开关相敏解调电路对信号全波检测,能检测到aF量级的电容变化,可以实现陀螺0.05(°)/s的分辨率.     

磁悬浮转子微陀螺中转子微加工方法的研究

微陀螺是微小卫星、微飞行器等装备中不可缺少的惯性器件，磁悬浮转子陀螺能克服机械支承和定位的摩擦，使之可以达到普通陀螺的精度要求。本文介绍了磁悬浮转子微陀螺的基本原理，根据产生电涡流、保持稳定悬浮和旋转的需求，对转子进行了设计，对比研究了溅射、蒸镀、冲压等三种加工微转子的方法，悬浮试验证明冲压铝箔法制备的转子能够满足微陀螺的要求。     

电容式位移传感器的线性度标定与不确定度评定

由于光刻投影物镜装调中电容传感器的线性度指标不能够满足位移调节精度的需求,本文提出了一种提高电容传感器测量线性度的方法。该方法采用压电驱动器提供位移进给;采用高精度激光测长干涉仪校准电容传感器的线性度,提供位移反馈以保证运动控制精度。采用高阶曲线拟合方法得到拟合系数对传感器线性度进行在线标定;对标定实验中的环境、安装、机构以及控制等进行不确定度分析与评定以保证电容传感器的线性度测量精度;最后进行电容传感器线性度的标定实验。实验结果表明:本文提出的线性度标定方法能够减小各误差项对于测量结果的影响,标定后传感器线性度由0.047 14%提高至0.004 84%,近一个数量级,并且线性度重复性较高,重复性偏差为0.38nm,全行程内线性度的合成不确定度为5.70nm,能够满足光刻物镜中位移控制精度的需求。     

片状转子磁悬浮控制系统的研究

转子轴向尺寸大幅缩小后形状趋于片状,轴向转动惯量与径向转动惯量之比增大,称为片状转子。片状转子磁悬浮轴承系统因陀螺效应而存在耦合,随着转子转速的升高,耦合现象也随之加强。针对片状转子的数学模型,基于交叉反馈算法,推算了轴向三控制点间的交叉反馈系数,对系统进行Simulink仿真,仿真结果表明以此算法为基础开发的控制系统能够完全消除因陀螺效应产生的耦合作用。实验对比了分散控制系统和交叉反馈解耦控制系统下控制电流和位移的幅值。交叉反馈控制系统下的控制电流和位移有明显减小。     

微机械陀螺检测接口建模及前置放大器优化

为了进一步提高微机械陀螺的极限分辨率,建立了基于SOI工艺的微机械陀螺的检测接口模型,并设计了与之相匹配的前置接口放大器.首先,根据陀螺表头的实际结构建立了微机械陀螺表头的RC集总参数模型和微机械陀螺检测接口的噪声模型,分析了检测接口主导噪声源及提高极限分辨率的措施.然后,在跨阻式前置放大器的基础上设计了改进的与检测接口匹配的T型前置放大器.实验结果表明:相比于跨阻式前置放大器,采用改进的T型前置放大器的等效噪声输入电流由1.18 pA/√Hz降低至0.27 pA/√Hz,对应的电容极限分辨率可达到0.62 aF/√Hz.结果显示,采用与检测接口匹配的T型前置放大器提高了微机械陀螺的极限分辨率.     

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.