误差补偿法在凸轮机构测绘中的应用

介绍了凸轮机构反求设计时凸轮数据预处理方法和误差补偿理论。根据引进的凸轮测绘出实际廓线的离散型值点数据,并进行型值点数据预处理,剔除可能存在的"噪声点",并推导出凸轮理论廓线方程。再根据凸轮设计理论,应用数值计算方法求解凸轮机构从动件角位移及角类加速度值。通过将角类加速度与期望角类加速度值进行比较,得出角类加速度误差,进而求得凸轮角位移误差。通过剔除角位移误差,对凸轮理论廓线进行补偿,进而获得更接近原始设计的凸轮实际廓线的离散型值点数据,从而为该类凸轮机构反求设计提供了科学的方法。     

基于多项式拟合的共轭凸轮反求设计

介绍了一种共轭凸轮反求的方法,测绘出凸轮廓面数据,通过Pro/E建立共轭凸轮机构的三维模并进行运动学仿真分析,得到反求前从动件的位移、速度和加速度曲线。将运动曲线进行无量纲化处理,分析出特征参数,并采用有控制条件的多项式运动规律对原来的运动规律进行拟合。最后运用Pro/E对反求后的凸轮进行运动学仿真,并与反求前的凸轮机构进行对比分析,通过仿真和试制,表明这种反求方法可以有效地提高凸轮的传动精度和工作效率。     

基于组件技术的凸轮从动件运动规律反求研究

研究了从CATIA数字模型中获取凸轮轮廓曲线上离散点坐标的方法,并以这些离散点及凸轮机构基本尺寸为依据,提出了反求机构从动件的运动规律的方法。利用CATIA提供的COM功能,结合其自带的V5AutomationAPI函数开发了反求从动件的运动规律算法及程序,并对反求所得结果与理论结果进行了误差分析,研究表明提出方法是准确的和适用的。     

对称性凸轮机构从动件升程廓线多项式运动规律的参数化研究

针对仅考虑边界条件的传统多项式运动规律的最大类速度和最大类加速度偏大的问题,通过研究具有最小加速度的凸轮类位移曲线、一次映射类速度图及二次映射类加速度图,把凸轮机构从动件升程廓线分为两段单凸的样条曲线,在样条边界点上找出影响加速度曲线的敏感参数,并在样条曲线上找到一个控制加速度曲线的敏感控制点,采用数形结合的方法建立对称性凸轮机构从动件升程廓线多项式运动规律参数化模型。通过该模型能获得不同条件下的最优标准位移方程,并以此作为凸轮从动件升程运动规律曲线,设计者只需要根据确定的推程角和升程,便可方便的设计出满足从动件升程加速度最小的凸轮廓线。     

凸轮机构的反求设计

介绍了胶印机离合压凸轮机构反求设计时剔除制造误差的数据分析方法.由凸轮实际廓线测得离散数据,根据凸轮设计理论推导出凸轮理论廓线值.应用数值计算方法,计算凸轮从动件的角位移及类加速度值.将类加速度与期望类加速度值进行比较,得出类加速度误差,进而求得角位移误差.剔除角位移误差后的数据更接近原始设计数据.     

基于遗传程序的凸轮轮廓曲线设计

将凸轮机构从动件的运动规律曲线离散为数据点对,用给定的数据点对与设计曲线的数据点对的距离作为适应度函数,采用遗传程序方法对凸轮理论轮廓线进行拟合.在初始群体产生和群体进化过程中,在通常的小概率变异基础上,引入大概率强制变异算子,改进了群体的适应度.设计实例表明,利用遗传程序方法能较好地拟合凸轮理论轮廓线,并能得到凸轮轮廓曲线的解析函数,实现凸轮轮廓曲线的自动设计.     

单张纸胶印机递纸机构运动规律反求设计

介绍了定心下摆式递纸机构共轭凸轮轮廓数据的反求方法,共轭凸轮机构从动件运动规律的反求设计过程.并对反求结果进行了分析,得出正向设计共轭凸轮机构从动件运动规律的工艺要求.该方法对同类产品的反求设计有一定的参考价值.     

凸轮部件反求设计与分析

基于反求设计的方法,以3次均匀B样条曲线和周期边界条件,建立了凸轮廓线的数学模型.利用数值算法对其进行了曲线拟合和光顺,同时,利用数值仿真方法,反求分析了滑块从动件的位移、速度、加速度响应和凸轮的转角分布规律.     

小波阈值法去噪在凸轮廓线反求中的应用

通过MATLAB小波工具箱函数,选择合适的小波函数和阈值,可以对一维信号进行有效的小波阈值去噪。在凸轮反求过程中所测得的凸轮廓线数据,可以作为两个一维信号进行小波去噪,去噪后得到新的凸轮廓线数据。对比去噪前后凸轮廓线公差带的变化,对去噪前后凸轮运动时的从动件加速度图进行对比分析,发现小波变换对凸轮廓线去噪有着良好的去噪效果,去噪后基本还原了凸轮的原始廓线。     

基于Matlab和UG的发动机配气凸轮的三维建模

根据发动机配气需要,设定了高次多项式配气凸轮的平底从动件升程函数、回程函数和约束条件;编写Matlab的M文件程序求出高次多项式凸轮轮廓曲线、曲线的点数据和生成从动件运动学曲线,并利用从动件运动学曲线分析高次多项式凸轮轮廓的曲线性能。利用UG的曲线生成功能、实体功能获得高精度、曲线光滑连续的高次多项式发动机配气凸轮的三维模型。     

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.