准双曲面齿轮几何参数计算方法的研究

介绍了求解准双曲面齿轮几何参数的基本原理.通过分析格里森求解方法的计算过程,建立了几何参数的迭代方程.在这些方程基础上,提出了一种几何参数计算的新方法.最后给出一个计算实例对新方法进行了验证说明.     

气体箔片轴承静态工作点求解

气体箔片轴承静态工作点的计算属于典型的弹流耦合问题,需要进行可压缩流体雷诺方程和板壳弹性变形方程的耦合迭代求解。为确定任意给定载荷下气体箔片轴承的静态工作点,提出了一种"二分法搜索+不动点迭代"的求解策略,二分法用于搜索偏心率,不动点迭代用于寻找偏位角。弹流耦合求解中雷诺方程采用基于质量流量守恒的差分法离散进行超松弛迭代求解,顶层箔片采用Kirchhoff薄板模型进行有限元求解,以整周式及三瓦插入式气体箔片轴承为算例进行了求解及分析,结果表明:偏心率、偏位角与文献[2]最大误差分别为6.60%和3.76%,且偏心率的误差随着外载荷的增大会显著减小;相对于刚性表面轴承,柔性表面轴承中的偏位角对偏心率的变化更加敏感。     

基于广义延拓逼近的暂态稳定分析

在求解暂态稳定的问题中给迭代计算一个更好的初值,则能加速网络方程的迭代速度,减少迭代次数.提出了广义延拓算法,并应用于网络方程迭代求解的初值预测,最后通过仿真算例证明了它的有效性.研究结果同时表明,此算法和传统方法相比,能减少计算量,从而节省暂态稳定分析的时间,具有广阔的推广应用前景.     

计入几何非线性时弹性连杆机构动力学方程的求解

当计入几何非线性及刚弹耦合项时，弹性连杆机构的动力学方程是非线性的，本文对这一类型的时变非线性振动方程的求解方法进行了研究，给出了一种实用迭代方法，并用这一方法研究了几何非线性对弹性连杆机构动力学性能的影响，得出了一些有益的结论。     

箔片轴承气弹耦合求解方法

气弹耦合求解是计算箔片动压气体轴承承载性能的有效方法。提出一种简单的箔片动压气体轴承气弹耦合求解方法。该方法以简单弹性基础模型为基础,将气膜厚度控制方程代入Reynolds是方程,获得箔片动压气体轴承气弹耦合控制方程,运用有限差分法结合Newton-Raphson迭代法对气弹耦合控制方程进行求解。计算方法获得的轴承内部压力分布与文献结果吻合很好。该方法的优势在于,省略了除最底层的牛顿迭代之外的其他所有迭代过程,使迭代次数大大减少,从而使计算效率获得提高。     

粘弹性复合结构动力响应数值分析方法

应用有限元方法进行粘弹性复合结构动力学响应分析时，由于粘弹性材料的时 变特性使动力学方程难于求解，本文给出了一种基于模态叠加法及迭代法相结合求 解复合结构动力响应的数值方法。首先利用复合结构的弹性模量系统特征解将复合 结构动力学方程变换为耦合的模态方程，其次采用迭代法求解耦合模态方程。通过 算例表明了该方法具有较高的计算精度及迭代过程具有较好的收敛性。     

球面配流副二维稳态压力场的数值求解方法研究

推导出基于球面坐标系的贴体网格生成方程,在贴体坐标系下利用有限差分法迭代求解雷诺方程,得到了球面配流副的二维稳态压力场,在迭代求解网格生成方程过程中利用平均近似的方法将隐式迭代方程转化为显式方程,大大缩短了求解时间。用球面配流副近似平面配流副进行了压力场计算,计算结果与电模拟法的结果非常接近。应用该方法对液压变压器球面配流副进行了压力场计算,计算结果表明,当相邻油口压力接近时过渡区域的压力场分布不能忽略。     

基于工作空间密度函数的平面冗余机器人的逆运动学求解算法

利用平面冗余机械人的结构参数结合傅里叶变换及卷积定理来构建非线性工作空间密度函数,并用该函数来描述多冗余机器人的工作空间。将工作空间密度函数仿真获得的工作空间与蒙特洛法求得的机器人工作空间进行对比,验证了算法的有效性。以工作空间密度函数为迭代方程,提出一种全新的迭代的算法来求解机器人逆运动学解析解。将该迭代算法与雅可比伪逆矩阵求逆运动学解的迭代算法进行对比,Matlab仿真结果验证了该算法在平面多冗余机械臂逆运动学求解精度及末端执行器位姿确定方面具有优越性。     

评定飞行器全方程控热试验温度数据不确定度的新方法

飞行器全方程控热试验过程中实时测量结构温度,代入气动加热计算方程中运算得到施加热流,反复迭代后,结构温度测量存在的不确定度进一步放大.获得较高精度的不确定度,采用传统的GUM评定方法耗费过高;建立各影响因素与结构温度之间的函数关系几乎不可能完成,无法采用蒙特卡洛方法进行评定.提出了一种评定全方程控热试验温度数据不确定度...     

无油涡旋空压机涡旋型线精度测试工艺研究

针对无油涡旋空压机型线精度要求高和型线质量检测难度大的问题,开展了圆渐开线涡旋盘加工工艺及测试技术研究.首先,采用高精度三坐标仪在涡旋盘同一高度层上采集了若干样点坐标;然后,对涡旋型线方程参数进行了初步估值,选择4个典型样点,并估算了其对应的展开角;接着,采用牛顿迭代法进行了迭代计算,得到了方程精确的待定参数,并计算了...     

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.