基于光盘数据系统和圆分度全息技术的激光栅角位移测量装置

本文研究基于光盘数据系统的角位移测量装置.硬件方面,研究如何依赖光盘系统的自动寻迹和激光聚焦而不是依赖昂贵的精密机械加工和微调来实现精密定位.软件方面,研究如何利用光盘极大的数据存储能力和各种压缩、纠错、编码技术来将已有的各种误差分离、误差抵消和误差衰减技术融合在一起而形成可以不断补充完善的圆分度多信息融合技术(其极限就是圆分度全息技术).而硬件和软件结合在一起,就构成一种基于现有成熟技术的新型圆分度测量系统--激光栅角位移传感器及系统.     

今年最流行的科技新产品

全息存储光盘：传统光学存储将所有信息存储在光盘表面，通过激光进行数据读取；而全息存储却利用了整个磁盘的所有空间。最新研制的全息存储光盘的单牒容量已经达到传统DVD的200倍。     

数控机床空间定位精度的测量与补偿

本文介绍一种使用美国光动公司的激光多谱勒位移测量仪，对数控机床进行空间误差检测的激光矢量测量新方法。该方法可以方便而快速地检测出机床的空间定位精度，包括3个定位误差、6个直线度误差和3个垂直度误差；同时还可以根据测量的空间定位误差数据生成误差补偿的代码，进而可以对其进行空间定位误差的补偿，大幅度提高了数控机床加工精度。     

采用柔性铰链实现多光盘的定位与夹紧

为适应光信息存储高密度,高容量,高速度和集成化的要求,提出一种新的单轴多盘光存储集成化方案,并设计了一种与之相适应的光盘定位与夹紧机构。该机构采用柔性铰链作为弹性元件,实现光盘的可靠定位与夹紧,具有结构紧凑,定位精度高,无间隙,无磨损,可靠性高等优点。理论分析和计算表明,能够满足光盘定位与夹紧的要求,采用该结构制作完成的原理样机,可在5000r/min的转速下平稳运转,光盘定位可靠,运行平稳,基本满足光学头信息读写的要求。     

线结构光测头的误差补偿

提出了一种线结构光测头误差检测和补偿方法。通过对线结构光测头测量精度的误差来源进行系统分析,确定测量过程中光平面倾斜和光条宽度的变化是产生测量误差的主要因素。提出了倾斜误差的检测方法并设计了检测装置,利用改进的BP神经网络模型实现了倾斜误差的补偿。实验证明,该方法能在很大程度上提高线结构光测头测量数据的精度,补偿后的误差接近光平面倾斜角度为零时的误差。     

基于参考轨迹修正的机床进给误差动态补偿研究

针对机床伺服进给系统的跟踪精度问题,对线性伺服动力学补偿器和闭环伺服控制系统进行了研究,提出了一种新的动态误差补偿方案,该方法通过修正参考轨迹,对伺服动力学和摩擦干扰引起的定位误差进行了预补偿.首先,对参考轨迹的速度和加速度曲线进行了调制,实现了精确跟踪;然后,根据预滤波器状态,对参考位置曲线进行了修正,从而消除了象限...     

转台定位误差谐波函数计算方法研究

为了保障转台定位误差谐波补偿准确性,针对一种谐波误差函数计算方法开展研究。 首先分析了转台定位误差谐波补 偿方法,阐述了基于坐标旋转数字计算方法(CORDIC)的谐波误差函数计算原理可行性;针对算法原理误差进行分析,分别建 立了与迭代次数 n、数据位宽 b 的量化模型,明确了算法在谐波补偿值计算过程的总量化误差;根据计算精度要求对 n 和 b 取值 进行设计,在现场可编程门阵列(FPGA)中实现谐波误差函数计算并进行实时误差补偿。 以谐波误差函数理论值为参考,仿真 证明了计算方法的有效性;以自制电路板为实验平台,证明了计算方法的总量化误差模型正确性;搭建转台测试平台验证定位 误差补偿效果,实验结果证明采用本文提出的谐波误差函数计算方法进行补偿,使转台定位精度由 29. 0"提高至 5. 3" 。     

微机辅助定位误差补偿方法

本文介绍一种微机辅助误差补偿方法。在该方法中,预先用双频激光干涉仪测出机床和仪器的定位误差,根据实测误差数据确定补偿点,并建立误差修正表存入微机,利用计算机的硬件和软件技术进行误差补偿。该方法的效果在感应同步器数显装置和MK 9027A 型CNC 光学曲线磨床上得到了验证。理论分析和试验结果表明,微机辅助误差补偿技术,可用来大幅度提高机床和仪器的定位精度。     

数控机床定位误差补偿策略研究

针对数控机床的定位误差,本文分析了定位误差的产生原因和补偿方式,并提出了一种区间分割补偿策略,对定位误差进行软件补偿。利用该补偿方法进行了误差补偿实验,实验结果表明该误差补偿策略原理正确、效果显著。     

水平式光电望远镜目标定位误差的预测

为了确定水平式光电望远镜的各主要误差对观测精度的影响,提高望远镜的指向精度,对它的目标定位误差进行了分析。针对水平式望远镜的结构特点,通过分析从被测目标到望远镜相面产生目标定位误差的光、机、电等各种误差因素,建立了水平式望远镜目标定位测量方程。应用蒙特卡罗法进行误差仿真,预测出水平式望远镜的目标定位误差,并对各误差的敏感性进行了分析。选取敏感性高的误差项建立误差补偿模型,对实拍星体误差进行补偿实验,结果表明:补偿后经轴转角误差标准差从66.4″降低到3.3″,下降了95%;纬轴转角误差标准差从49.4″降低到5.6″,下降了89%。所用方法和模型能够对主要误差进行分析和预测,可为水平式光电望远镜的总体设计提供参考。     

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.     

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....     

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。     

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.