震实式造型机工作台翻转机构的设计与运动仿真

针对震实式造型机工作台的翻转机构,利用解析法设计了翻转机构为四杆机构。根据四杆机构杆件长度,利用Pro E软件构建机构各构件,并进行虚拟装配,然后进入机构仿真模块对机构进行运动分析和仿真,仿真结果表明此四杆机构能够实现震实式造型机翻转机构的运动要求,并且运动过程中无干涉出现。     

装载机八杆机构工作装置多目标优化与仿真

提出了一种实用性和可操作性较强的八杆机构多目标优化方法.将设计变量矩阵分解为两组耦合度较小的矩阵,提取重要度最高的几个优化目标,把其他优化目标转换成约束条件,建立起八杆机构多目标优化数学模型,同时创建了工作装置多目标优化流程.将该数学模型加载于系统动力学分析软件ADAMS,借助该软件的内建函数,把多目标优化转换成单目标优化,实现了优化过程的函数驱动与函数监测.最终实现了工作装置的快速优化与仿真.     

面向对象的多杆机构多目标多约束优化设计方法

针对工程实际中多杆机构多目标多约束优化设计问题,提出了一种基于Isight与ADAMS集成的面向对象多杆机构的结构优化设计方法。采用面向对象的结构建模方法 ,借助多体动力学仿真软件ADAMS,建立多杆机构仿真参数化模型,实现Isight内置搜索算法解决多杆机构多目标多约束条件下的结构优化问题。以一种六连杆机构的优化设计为例,实验结果表明,能够通过一次建模可以满足不同约束及优化目标下的结构设计参数优化组合。     

采用配重法分析3-PRS并联机床静态平衡

配重法分析3-PRS并联机床的静态平衡问题,验证其优缺点。首先设计了平衡机构,动平台通过平行四边形伸缩机构平衡,其它三杆分别通过三个配重滑轮机构进行平衡。分析了并联机床各运动构件的质心,推导出了驱动杆质心和动平台的质心的方程表达式,通过平衡分析和算例得出,可以实现机床在整个工作空间任意位姿下驱动杆均不需要输出关节力克服机床重力。最后利用ADAMS仿真软件对施加配重的并联机床仿真验证,证明了理论分析是正确,配重法不需要对机床进行维护,并可以完全实现并联机床的静平衡。     

基于广义杆组对多环路三移一转位移输出机构的型综合

基于广义杆组提出了一种对多环路三移一转位移输出机构型综合的新方法。该方法把运动链当成广义杆组逐个添加在输出构件上,进一步扩展了Assar杆组法在空间的应用。分析了单环路到多环路杆组自由度与输出构件自由度和位移参数的关系,得到了添加自由度为0的广义杆组对输出构件自由度和位移参数的变化关系。综合了三移一转位移参数的杆组,建立了交集运算规则。通过组合两个广义杆组综合输出构件自由度为2、3、4单环路机构,再添加自由度为0广义杆组,得到了双环路机构。通过自由度为0广义杆组综合出多环路机构的例证,展现了该方法在空间机构综合方面的全面性和有效性。     

基于ADAMS的3-PTT并联机构运动学和动力学仿真

以3-PTT型并联机构为研究对象，应用ADAMS软件建立了由静平台、动平台、定长杆等构件构成的并联机构虚拟样机模型。详细论述了建模方法、模型的ADAMS描述、仿真过程，并利用该模型对3-PTT并联机构的运动学和动力学进行了仿真，实现了在计算机上仿真分析并联机构的运动和动力性能，为并联机构设计提供了一套有效的分析方法。     

基于改进的杆组邻接矩阵的平面运动链类型自动综合

为了利于计算机自动综合,提出了改进的Assur杆组邻接矩阵的平面运动链类型自动综合。首先针对构件数主动件数和选定的杆组,根据杆组组成理论求出对角线元素以及它们的不同组合,然后归纳了综合方法和步骤,定义了选定杆组邻接矩阵。因为综合法在综合构件的过程中根据杆件数、主动件数及杆组类型这些因素分类细化了运动链,并同时判断同构构型,所以综合过程具有很强的规律性,效率也很高,可以减少后面运动链同构识别与刚性子链识别的计算量,特别是对于计算机自动综合多杆多主动件的平面机构运动链,并成功应用在综合12杆以下的平面机构运动链类型。并且以6构件单主动件机构运动链为例进行了类型综合。     

平面四杆机构综合数值比较法的研究

提出了平面四杆机构综合（包括函数综合、轨迹综合和导引综合等三类基本问题）的数值比较法。在研究了四杆机构的连杆转角曲线和主从动连架杆转角曲线的基本特征后,根据当今计算机的强大的计算、存储、比较、检索与图形能力,对四杆机构综合的三类基本问题提出了相应的转化方法,均可以求出一系列基本满足给定要求的解,而后再根据每类问题提出的约束条件进行优化,得到满意解。利用该软件开发的软件可实现连杆机构综合的自动化与可视化。     

铰链六杆间歇机构综合的数值方法

以机构学知识中的常定曲率圆点曲线和常定曲率圆心曲线为理论基础 ,采用“直线扫描”法综合铰链六杆间歇机构中的基础四杆机构 ,然后用“切线包容”法综合输出二级杆组 ,并讨论了铰链六杆间歇机构的曲柄存在条件。应用该方法 ,编制了一套铰链六杆间歇机构综合的可视化设计软件 ,综合出了具有高质量停歇的铰链六杆间歇机构 ,实现了铰链六杆间歇机构综合的自动化与可视化。该软件不仅设计速度快 ,且对于给定停歇角从 2 5°到 14 0° ,输出摇杆的摆角从 10°到 160°间的任意组合均能得到多个满意的解     

基于Pro/E的并联机床动态仿真

利用Pro/E 软件设计出3-TPT并联机床机构,对各个零件进行建模.利用该软件的结构模块对各个构件进行装配,并对驱动杆添加驱动器,并设置好驱动器的参数.运用机构模块对构件的装配进行仿真,以观察整个机构的实际运动过程.对运动过程所得的结果进行分析,同时检查构件间是否存在干涉,最后生成并联机床运动过程的视频文件.     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.