基于逆向工程的混合建模技术研究

基于逆向工程的混合建模是目前应用较为广泛的逆向建模方法。简要介绍了以软件Geomagic Studio和SolidWorks为平台的混合建模的一般流程,通过对由不同几何特征曲面组成的模型进行混合建模为例,详细介绍了基于点云的逆向建模,并对逆向建模得到的NURBS曲面进行正向建模最终得到产品的CAD实体模型。实例表明混合建模能融合正向设计与逆向建模的优势,具有较高的建模效率以及参数化修改功能,为复杂模型的逆向设计提供了一种新的解决方法。     

基于形态分析法的逆向参数化建模

近年来,随着逆向工程的发展,逆向参数化建模在产品创新设计中起着越来越重要的作用。通过对形态分析法进行分析、改进,以实现与逆向参数化建模相结合,提出基于形态分析法的逆向参数化建模方法,并详细介绍了这种逆向参数化建模方法的优势及其一般流程。以逆向参数化建模软件Geomagic Design X为平台,通过对电热水器控制板进行基于形态分析的逆向参数化建模及误差分析,验证了该建模方法的优势,为产品的逆向创新设计提供了一种有效的建模方法。     

基于逆向建模元素的个体化医疗器械设计

逆向工程中的参数化建模方法是逆向建模研究的重要方向之一。通过对目前广泛应用的逆向参数化建模方法进行分析,提出了基于逆向建模元素的产品模型设计,将功能分析和形态分析相结合,用于提取建模元素,建立基于功能-形态-参数模型的建模方法,并详细介绍了这种建模方法的优势及其一般流程。同时以逆向参数化建模软件Geomagic Design X为平台,通过典型医疗器械实例的参数化建模验证了该建模方法的优势,为个体化医疗器械逆向建模提供了一种更加有效的建模方法。     

基于三角曲面的逆向工程CAD建模方法

根据目前逆向工程CAD建模中存在的问题，提出一种基于三角Bezier曲面模型初始表达的跨平台产品逆向工程CAD建模策略，既能利用三角Bezier曲面的优势，又能有效地与通用CAD软件集成。对涉及产品逆向建模方案、数字化测量规划、实际建模过程和再创新设计等具体内容进行了详细阐述，并结合具体实例说明了该方法的可行性和有效性。     

逆向工程中的参数化建模技术及应用

逆向参数化建模方法是在逆向工程的基础上,加入参数化技术形成的一种新的建模方法,该方法不仅有利于提取原始设计信息,重建更为精确的CAD模型;而且易于实现模型的参数化修改,推动产品的创新设计。简要介绍了逆向工程的概念和逆向参数化建模方法,以汽车后视镜为例,利用Geomagic Studio软件对扫描点云进行处理,拟合出特征识别后的初始曲面。通过参数转换功能把初始曲面导入Solidworks中进行编辑,最后得到汽车后视镜的参数化模型。实践表明这为反求模型的参数化建模提供了一种切实可行的方法。     

基于逆向工程技术的汽车橡胶密封条模具的再设计

逆向工程技术是模具制造业进行模具设计制造体系的一种新手段。提出了结合逆向工程专用软件与商用CAD/CAM UG软件进行汽车橡胶密封条挤压模具再设计的流程,并分析了某侧窗模具零件再设计的特点,详细论述了该模具由初始设计制造—试用修模—逆向重新建模的再设计过程。实践结果表明采用逆向工程技术,提高了零件再设计效率,满足了产品的精度要求。为模具再设计实现高精度、高效率、低成本提供了指导意义,具有较高的应用价值。     

基于设计知识重用的逆向产品创新

逆向建模技术在产品创新设计中起着越来越重要的作用。通过功能分析与形态分析相结合,获取逆向建模所需知识,然后以逆向建模方法创建基于功能-形态-参数的新产品模型,实现了基于设计知识重用的逆向产品创新设计。以Geomagic Studio逆向建模软件和Solid Works软件为平台,通过对手臂夹板进行基于设计知识重用的逆向产品创新,验证了该方法的优势,为产品的逆向创新提供了一种有效的设计方法。     

复杂曲面类模型的逆向建模技术的研究

为了缩短零件的开发周期,用逆向工程建模和创新已经成为一种越来越受欢迎的方法。逆向工程在没有零件CAD文件的情况下,能够迅速重新构建现有经典的设计并开发新设计。以游戏手柄为例,从原始点云数据采集、点云数据的编辑、逆向建模(CAD模型的重构)以及产品CAD模型的质量分析四个方面介绍复杂曲面类模型的逆向建模过程。     

基于Pro/SCAN-TOOLS的鼠标逆向工程设计的应用研究

逆向工程是三维数字化设计与快速原型制造大趋势下的一项先进设计技术,是吸收引进先进技术的重要技术手段。以电脑鼠标为例,阐述利用Pro/E逆向模块及其逆向建模原理进行复杂型面产品逆向工程设计的方法和过程。     

基于CMM和光学扫描的集成测量与混合建模

针对现阶段复杂零件在逆向测量与建模上的不足,提出了一种基于CMM和光学扫描的集成测量与混合建模的技术。对复杂的零件,首先将其表面划分为规则特征和非规则特征,分别对其应用两种三维测量技术获取产品表面数据,然后各自进行建模,再将两部分模型坐标系对齐,利用布尔原理进行裁剪,最终得到产品的CAD实体模型。通过此方法对复杂零件实现了集成测量和混合建模。实验结果表明,该方法可以提高复杂零件在集成测量下的逆向设计的效率和质量。     

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.