基于质量功能展开和证据理论的复杂装备维修可达性综合评价

为克服已有的维修可达性定义不能反映复杂装备的缺点.提出了复杂装备维修可达性的概念,在此基础上构建了可达性的综合评价方法.首先,采用质量功能展丌分析可达性要求,以及可达性具体要求和技术措施之间的关系,建立各组成部分的评价指标体系;然后.依据质量功能展开、证据理论等计算出各组成部分的评价等级;最后,综合考虑各组成部分的重要度及维修频率,获得复杂装备的维修可达性评价等级.通过实际案例研究,验证了该方法的可行性.     

维修性可达性设计中的人体手臂控制

可达性是机械产品维修性的主要指标,在设计阶段对产品进行可达性分析是维修性设计的重要内容。通过虚拟人手臂的维修动作仿真,结合碰撞检测对产品的可达性进行分析。采用D-H法建立了手臂简化运动学模型;基于粒子群算法对手臂姿态进行逆解运算;最后对Delmia进行二次开发,实现对人体手臂的运动控制,并对拆卸曲轴螺钉这一具体维修任务进行仿真验证,取得良好效果,证明本文方法的有效性。     

激光快速成型技术在工业设计中的应用与前景

传统的工业生产手段已不能满足市场的需求,快速成型技术的出现很好地迎合了工业设计的发展需求,它能够快速转化设计思想,是制造技术领域的革命性发展,而激光快速成型技术更是其中的重要组成部分,基于此,对激光快速成型技术进行了深入的研究和分析。     

3D打印在快速熔模精密铸造技术中的应用

针对3D打印技术在熔模精密铸造行业的应用现状问题,对快速熔模精密铸造技术的工艺原理及国内发展概况进行了研究,分别重点研究了基于光固化成型技术、选择性激光烧结技术及熔融沉积成型技术的快速熔模精密铸造技术的国内研究现状,并深入剖析了这三种技术各自的优势与不足。其中,基于光固化成型技术的快速熔模精密铸造技术主要存在型壳易胀裂技术难题;基于选择性激光烧结技术的快速熔模精密铸造技术虽可有效克服型壳易胀裂技术难题,但存在原型零件强度不高、易翘曲变形等问题;而基于熔融沉积成型技术的快速熔模精密铸造技术则因原型尺寸精度较低、表面质量较差导致其实用性较低。研究结果表明,目前该三种快速铸造技术都还存在各自的技术瓶颈,这在很大程度上限制了其推广应用。     

射流电铸快速成型系统研究

将射流电铸与快速成型技术有机结合起来,发展了一种直接快速成型金属零件的新方法--射流电铸快速成型技术,并分析了其成型原理与系统结构组成特点.基于Windows平台,采用NC嵌入PC的结构模式构建了其计算机控制系统,对该控制系统的软硬件组成、结构和功能特点进行了分析和研究,并用研制开发的射流电铸快速成型设备直接快速成型了具有良好形状和尺寸精度的金属铜零件.     

基于快速成型的快速模具制造工艺分析

介绍了基于快速成型的快速模具制造技术的工艺原理、分类、成型方法、技术特点以及与传统成型方式的区别。从模具的寿命,模具的制作成本,模具的生产周期等方面对几种典型快速模具制造技术系统进行了比较和归纳。分析了快速模具制造技术面临的关键问题,展望了基于快速成型原理的快速模具制造的应用前景。     

应用快速成型技术进行新产品开发

分析市场需求的变化与对新产品开发的新要求,提出基于快速成型技术的新产品开发一般流程,并以喷雾器的开发为例进行实例研究.总结了应用快速成型技术进行新产品开发的优越性.表明在新产品开发中运用快速成型技术能够完全适合市场变化对新产品开发提出的新要求,并且具有很大的实用价值。     

快速模具系统工艺特点与分析

采用传统的模具加工方法,制造周期长且成本高。快速成型配合传统制模技术不仅适合单件小批的模具快速制造,而且能适应各种复杂程度的模具快速制造。介绍了基于快速成型技术的快速模具制造技术工艺原理、分类、成型方法及其技术特点以及与传统成形方式的区别。从模具的寿命,模具的制作成本,模具的生产周期等方面对几种典型快速模具制造技术系统进行了比较和归纳。分析了快速模具制造技术面临的关键问题,展望了基于快速成型原理的快速模具制造的应用前景。     

装备维修可达性综合评价方法研究

针对现有装备维修可达性评价方法的不足,构建了维修可达性评价指标体系,研究了在虚拟仿真环境中的单个指标评价方法,利用指标关联度和有向图构建了评价关联矩阵,基于矩阵积和式提出了维修可达性综合评价模型.以装备的动力系统为实例进行了方法验证,结果表明该方法对于实现在装备数字样机设计过程中,同步开展装备维修性评价工作具有重要参考价值.     

快速成型技术在新产品开发中的应用

分析了市场需求的变化对新产品开发提出的新要求，介绍了基于快速成型技术的新产品开发一般流程．并以喷雾器的开发为例进行了实例研究。表明在新产品开发中运用快速成型技术，能够缩短开发周期，降低开发成本，提高制造精度。     

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.