机械零部件可再制造性评价模型研究与应用

再制造评价作为绿色再制造工程的设计基础,是开展再制造的前提。为了评价机械零部件的可再制造性,判断其是否适合进行再制造,基于层次分析法,提出一种以再制造相对加工指数为目标层的可再制造性评价模型;建立了涵盖技术、经济和环境三个方面的再制造评价指标体系及量化方法,并根据层次分析法确定各评价指标的权重,计算出再制造相对加工指数。以柴油机曲轴为案例,得到再制造相对加工指数为0.70,表明该曲轴可再制造性较好。     

[机械装备再制造]考虑失效特征的废旧零部件再制造成本预测模型研究

分析了废旧零部件失效特征对其再制造成本的影响,建立了一种基于失效特征的废旧零部件再制造成本预测模型,该模型将半监督学习与最小二乘支持向量机回归（LS-SVR）算法相结合,实现了在只有少量已完成再制造的废旧零部件样本和大量未知再制造成本的零部件样本的条件下,对废旧零件再制造成本的预测。该算法加入了k最近邻(kNN)算法,以kNN为辅、LS-SVR为主对未标记的样本进行置信度评估,将各阶段最优未标记样本逐步添加进有标记的样本集中,逐步更新预测模型,能够有效降低噪声,提高模型精度。经案例验证,提出的算法具有良好的回归预测能力和泛化能力。     

考虑失效特征的废旧零部件再制造成本预测模型研究

分析了废旧零部件失效特征对其再制造成本的影响,建立了一种基于失效特征的废旧零部件再制造成本预测模型,该模型将半监督学习与最小二乘支持向量机回归(LS-SVR)算法相结合,实现了在只有少量已完成再制造的废旧零部件样本和大量未知再制造成本的零部件样本的条件下,对废旧零件再制造成本的预测。该算法加入了k最近邻(kNN)算法,以kNN为辅、LS-SVR为主对未标记的样本进行置信度评估,将各阶段最优未标记样本逐步添加进有标记的样本集中,逐步更新预测模型,能够有效降低噪声,提高模型精度。经案例验证,提出的算法具有良好的回归预测能力和泛化能力。     

离心压缩机叶轮主动再制造设计和时机调控方法

针对目前再制造中零部件经常出现的“滞后再制造”或“提前再制造”问题,提出了离心压缩机叶轮主动再制造设计和时机调控方法。选取关键零部件特征结构,结合疲劳寿命理论和叶轮设计基础,建立结构与服役性能的映射模型,实现关键零部件的主动再制造设计。通过优化特征结构参数,改变零部件服役寿命和再制造临界点,并与产品综合性能劣化拐点相匹配,完成零部件主动再制造时机调控。以PCL8L型叶轮为例,基于构建的叶轮特征结构(出口安放角、入口安放角和后缘厚度)与寿命之间的量化关系模型,在当前定期维护需求下,通过理论计算和仿真分析,验证了主动再制造设计和时机调控方法的可行性。     

基于线性回归模型的机电产品再制造费用预测

针对再制造决策者在产品再制造成本发生前无法决策的问题,提出运用线性回归模型,建立产品零部件失效类型信息与产品再制造费用之间的线性关系;基于同类产品零部件失效类型信息以及同类产品再制造费用的统计,对产品的再制造费用进行事前预测,并根据各类零部件的质量属性,对产品再制造的预测费用进行修正,获得相对准确的产品再制造费用预测,并用预测费用与实际费用的相对误差描述再制造费用预测的准确性。     

基于失效模式的曲轴再制造工艺优化方法研究

针对曲轴再制造过程中工艺路线复杂多样的问题,从曲轴的工作状况、材料选择、失效原因和损伤程度等方面进行了研究,提出了基于失效模式的曲轴再制造工艺优化方法。通过故障树分析法分析了曲轴失效的主要原因,用树形图表示出来,从中提取了影响再制造工艺的关键因素作为失效特征;基于实际工作经验给出了失效特征的量化标准,并将量化结果作为选取再制造工艺的主要条件;根据再制造工艺标准剔除了不合理的工艺路线,并将结果用与或图简明表示出来,建立了涵盖经济成本与时间成本的再制造成本函数,对结果数据进行了无量纲化处理,分析比较了简化后的工艺路线,选取了成本最低的路线作为最优再制造工艺路线;选取DB-7020帕萨特汽车废旧曲轴为目标,从磨损、裂纹和变形失效角度进行了分析,应用再制造工艺优化方法获得了可行的再制造工艺路线,并通过再制造成本函数评价得到了最优路线。研究结果表明:再制造工艺优化方法可以解决由于废旧曲轴失效形式和失效程度不同而导致的工艺复杂性问题,能够提高再制造工艺选择的合理性和再制造效率。     

基于TOPSIS的汽车发动机再制造方案综合评价

阐述了我国再制造汽车发动机等零部件产品的现状。针对汽车发动机再制造方案缺乏优化选择的问题,建立以经济性、技术性、资源能源性和环境性为指标的汽车发动机再制造方案评价体系,依据指标属性特征对各个指标的量化方法进行了分析,提出一种基于逼近于理想值的排序方法 (TOPSIS)的汽车发动机再制造方案综合评价方法,并通过实际应用案例,对该评价方法进行验证。     

基于轴心轨迹特征的发动机曲轴再制造性分析方法

运用主动再制造理论对再制造毛坯质量的不确定性进行了分析研究,提出了一种基于轴心轨迹特征的发动机曲轴再制造性分析方法。该方法通过运用不变矩算法提取同一发动机曲轴不同磨损状态下轴心轨迹的特征量,建立特征量与磨损量之间的映射关系,来判断发动机零部件的再制造性,从而实现对任意状态下曲轴磨损的量化。试验结果表明,运用该方法对曲轴磨损量进行识别具有较高的精度,为寻求曲轴服役期内最佳再制造时机提供了较为准确的判别依据,同时为服役期内伴随产品失效的同批次再制造毛坯质量的不确定性控制等问题提供了解决方案。     

复杂产品多粒度再制造性综合评价方法

为提高复杂产品再制造性评价的全面性,根据复杂产品层次性的特点和再制造过程,构建了产品多粒度再制造性评价模型,该模型描述了从产品层到零件层的评价指标和量化方法。给出了粗粒度指标的量化公式,用于产品和组件层的可再制造性评价;针对细粒度指标难以量化的特点,提出了基于层次分析法(AHP)的细粒度评价方法,用于零件层的可再制造性评价。为提高评价效率,提出了逐层递归再制造性综合评价方法。最后,验证了所提方法的可行性与有效性。     

基于失效模式传递网络模型的产品再制造模块化方法

绿色再制造是支持再循环经济的关键技术，而产品模块化可以有效促进再制造，提高产品再利用性。针对绿色再制造的产品模块化问题，提出一种基于失效模式传递网络模型的产品模块化方法。分析产品零部件失效模式，构建了失效模式—循环再利用方式传递网络模型，应用模糊集合理论构造不同层次之间的模糊关系矩阵，通过逐层映射以判析各零部件的循环再利用方式。综合分析零部件间功能—结构的关联关系及再制造特性的关联关系，考虑到产品寿命终结阶段再制造性指标的信息不完整性和模糊性，建立了综合关联矩阵。以零部件功能和结构的关联关系为聚类基础，基于传递闭包的聚类算法，获得不同的零部件聚类方案，建立产品模块化层次结构，以模块独立性和再制造性的最小描述长度为准则，实现模块的合理划分。以永磁减速起动机为例，验证了所提方法的有效性。     

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.     

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.