复杂产品多学科虚拟样机元建模框架

为实现复杂产品虚拟样机中各类多学科异构模型的有效重用和集成,以制造领域广泛存在的复杂产品为对象,讨论了复杂产品虚拟样机的多学科特点及其对传统建模仿真理论带来的挑战;结合元对象机制和面向组件的建模思想,提出了一种新的面向复杂产品多学科虚拟样机的元建模框架,并对框架中各抽象层次模型规范(元元模型、元模型和系统高层模型)进行了形式化定义和语义讨论.在起落架多学科虚拟样机应用实例中,基于元建模框架中的系统高层模型进行了产品的统一建模描述,实现了复杂产品中多学科异构模型的更高层次抽象和集成重用,验证了元建模框架的有效性.     

复杂产品虚拟样机本体元数据建模方法与应用

为了构建复杂产品虚拟样机统一模型,更好实现信息交换、共享、互操作及模型重用,结合元建模理论和本体,提出一种基于本体元数据模型的虚拟样机信息建模方法。根据产品本体元数据概念模型,并结合虚拟样机过程、产品、资源、知识在本体元数据模型中语义关联关系,构建虚拟样机本体元模型。最后以虚拟样机元数据模型EXPRESS描述,说明了该方法具体应用过程。     

机械产品虚拟样机本体元模型转换方法

为有效支持机械产品虚拟样机统一模型转换仿真及优化模型,基于元模型转换理论,构建虚拟样机EXPRESS本体设计元模型,分析基于设计元模型接口语句与变量型转换规则的学科元模型转换方法。最后以某发动机曲轴飞轮组元模型为例,转换并实例化虚拟样机运动仿真模型和有限元模型,证明了该方法的正确性、有效性与实用性。     

面向复杂机电系统虚拟样机技术研究综述

为了使复杂机电系统虚拟样机替代物理样机并提高复杂机电产品设计的质量和效率,综述了复杂机电系统虚拟样机若干关键支撑技术的研究进展和目前存在的问题,主要包括虚拟样机定义、建模技术、多领域仿真、多学科设计优化、系统集成方法以及模型管理,探讨了复杂机电系统虚拟样机技术及其发展方向。为复杂机电系统虚拟样机设计奠定了研究基础。     

面向复杂产品的可重构虚拟样机技术研究

针对复杂产品基于已有知识实现快速设计问题,对产品设计、分析仿真和协同优化过程中模型和知识的重用进行了深入分析,提出了支持新产品开发的可重构虚拟样机构建方法.通过对复杂产品虚拟样机技术分析,研究了可重构虚拟样机的构建过程和建模方法,建立了可重构虚拟样机的基本类图、活动图和映射关系图;在新产品设计过程中参数驱动可重构虚拟样机模型,实现新产品的快速设计和分析及优化.最后,以锤式破碎机主轴为例,实现了可重构虚拟样机的应用,证明了该技术对复杂产品的快速设计具有重要意义.     

基于知识的虚拟设计研究

研究了虚拟制造的体系结构和虚拟设计的模型问题，提出了层次化建模思想及元模型、机构模型、产品模型的概念，将整个虚拟设计模型分为元模型、机构模型和产品模型，建立了三个模型的结构，并给出基于知识的虚拟设计的建模方法和装配模型。     

虚拟样机多学科协同设计与仿真平台实现技术

在分析产品协同开发平台的功能框架以及主要协同模式的基础上，深入研究了虚拟样机多学科协同设计与仿真平台的分布式计算模型，及其协同运行管理、协同产品开发资源库管理、分布数据的协同交互管理与系统实现技术。基于COM／DCOM的建模与仿真工具协同、支持仿真联邦管理的数据库设计和CORBA的应用实现技术，开发了原型系统。该系统支持Internet网络环境下各种建模与仿真工具跨平台、分布交互与异构集成，可有效支持复杂产品虚拟样机的协同开发。     

复杂产品多学科虚拟样机顶层建模语言研究

为了在复杂产品虚拟样机开发过程的不同阶段,以及在工具和部门之间更加准确地描述系统的顶层模型,提出了一种描述多学科虚拟样机顶层系统结构、行为和内部相互关系的系统顶层建模语言。在顶层建模语言中,把系统模型划分为静态结构模型和动态行为模型。为了顶层建模语言的扩展,定义了顶层建模的统一建模语言特征;采用基于可扩展标记语言的数据交换格式,规范顶层建模在不同工具间的信息传递;顶层建模语言遵从模型驱动体系结构的思想,从面向编程平台、通信平台和工具平台映射成为模型的实现。简要介绍了顶层建模语言的实现工具——顶层建模集成开发环境。最后,给出了计算机生成的武装兵力系统的例子,说明了顶层建模语言对复杂产品虚拟样机建模的有效性。     

面向多学科协同开发领域的集成建模方法

为实现复杂产品研发过程中不同学科的信息共享,消除系统集成、协同仿真和系统优化的障碍,提出了基于本体元模型的数字化样机构建方法.分析了基于本体元模型的多领域集成建模的可行性,利用统一建模语言的扩展模型构建了本体的元模型核心包;基于本体理论分析了复杂产品协同开发领域的概念及其关系,构建了多学科协同领域信息集成框架;基于本体元模型建立了涵盖产品定义信息、研发方法信息和研发流程信息的数字化样机模型,支持产品在研发过程中的多抽象层次演化、多粒度层次分解和多学科协调优化,控制复杂产品的整个研发过程.以有源相控雷达为例对所提方法进行了说明.     

复杂产品虚拟样机学科模型的CAD/CAE一体化研究

为有效地解决复杂产品虚拟样机各学科CAD/CAE信息的交换与共享,提高产品开发质量和效率,提出基于STEP标准、元建模理论和MBD模型描述学科模型的方法。研究了学科模型的CAD/CAE信息联动过程及其变化规律对CAD/CAE一体化的影响,提出了基于历史和非基于历史的混合建模方法,并搭建了学科模型的CAD/CAE信息自动同步联动机制。以某汽车自动变速器行星齿轮机构、液力变矩器以及电控单元的CAD/CAE一体化建模为例,说明了元建模方法搭建基于STEP不同学科模型的CAD/CAE信息同步联动在复杂产品建模中的应用,验证了学科模型设计信息与仿真分析信息同步联动的正确性、有效性与实用性。     

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.     

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....     

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.