不确定信息的机械产品设计方案评价方法

机械产品设计方案评价中,针对评价指标值具有模糊性、指标权重具有不完全性的问题,引入模糊数据包络分析(DEA),分析模糊DEA在不完全权重信息处理方面存在的不足,提出改进的模糊DEA评价方法。该方法首先将指标值转化为无量纲的梯形模糊数,然后以梯形模糊数为基础,以不完全权重信息为约束,建立只有输出指标且含有偏好信息的模糊DEA模型,最后,基于去模糊化方法,将模糊DEA模型转化为确定性模型并求解。通过实验分析,验证该方法的合理性和可行性。     

模糊数据包络分析法在产品方案评价中的应用

针对传统方法在方案评价时需给出各目标权重的局限,将数据包络分析(DEA)方法引入机械产品方案评价中,针对概念设计方案指标值具有模糊性的特点,在传统C2R模型的基础上,根据模糊数的排序原理,提出了一种新的模糊DEA模型。通过构造评价系统的相对最差方案,作为虚拟方案,建立模糊评价模型,根据模糊数排序原理转化为确定的优化模型来计算各方案的效率评价指数,从而可对包括DEA有效的所有设计方案进行评价排序。实例表明,该模型无须构造α截集,计算简单方便,可用于评价同时具有确定性和模糊性指标值方案的相对有效性,因而具有更广泛的应用范围。     

不完全信息条件下产品方案评价方法

针对指标权重和指标值信息都不完全的方案评价问题,提出了一种基于二次规划的方案决策方法。首先将机械产品方案的评价问题描述为不完全信息条件下的多目标决策问题,然后在对决策矩阵规范化处理的基础上,将不完全指标权重和指标值信息用线性关系式表示并将其视为未知变量构建二次规划模型,经求解得到指标权重和指标值,进而可计算出方案的评价值,选出最优方案。介绍了该方法的基本原理和步骤,最后通过一个机械产品的评价实例证明了方法的实用性和有效性。与其他方法比较,本文的方法简单方便,计算量小,保证了较强的实用性。     

基于二元语义DEMATEL和DEA的多属性群决策方法

传统多属性决策方法通常主观地确定评估指标权重,没有考虑指标间的影响关系;数据包络分析法无需指标权重,但其优化得到的指标权重不能反映客观的指标重要性。针对上述问题,将决策实验与评价试验法和数据包络分析方法相结合,采用决策实验与评价试验法分析指标间的影响关系,确定指标的重要度,从而修正数据包络分析优化得到的指标权重。采用二元语义表达模型处理专家给出的语义评估信息和指标影响关系信息,通过分析专家评估值与其他专家评估值的贴近度确定专家动态权重,并采用结合二元语义决策实验与评估试验法的数据包络分析模型计算候选方案的综合评估值。以某医院传感器医疗设备选择为例,验证了所提方法的有效性。     

基于模糊DEA/AR的知识化制造模式评价和选择方法

考虑知识化制造模式的复杂度,以知识化制造模式为决策单元建立了数据包络分析模型,提出一种用于制造模式相对有效性评价的模糊数据包络-保证域方法。模型中的输入变量和输出变量以三角模糊数表征,采用权重保证域以避免传统非阿基米德无穷小量求解对评价结果的影响,引入α截集计算决策单元模糊有效性的上下界,实现决策单元的相对有效性评价。在此基础上,给出一种基于模糊有效边界值的制造模式相对有效性排序方法,为知识化制造模式选择提供依据。最后,通过试验算例验证了该方法的可行性。     

基于三角模糊数灰色关联理论的多层次综合评价模型研究

针对利用灰色关联法对多层次综合评价模型的最优设计方案选择时,设计方案的指标中存在模糊指标的问题,提出了基于三角模糊数灰色关联理论的多层次综合评价模型。将三角模糊数引入灰色关联法对多个产品设计方案的选择中,首先根据模糊指标和三角模糊数的对应关系,把设计方案中的模糊指标转变为对应的三角模糊数,进而针对传统的灰色关联系数的求解公式,推导出基于三角模糊数的灰色关联系数求解公式,然后利用三角模糊数运算规则和三角模糊数排序方法,以及推导的三角模糊数灰色关联系数公式,得出方案的最终模糊关联度系数,最后通过对方案最终的模糊关联度系数的比较得出最优方案。该方法把模糊的描述转化为最终的模糊关联度系数,整个过程保留了模糊的性质,解决了利用灰色关联理论对多层次综合评价模型的方案选择中存在模糊指标的问题,最后通过一个算例说明了利用该方法求解最优方案的过程,结果表明:该方法针对复杂的、多层次的、有模糊信息的问题,有较好的可操作性和现实一致性。     

基于模糊增强DEA和改进FMEA的制造技术选择方法

制造技术/设备选择是典型的多属性决策问题,针对AHP等方法确定评价指标权重具有的主观性,采用数据包络分析(DEA)方法评价制造技术。针对传统DEA模型处理不确定性信息能力差以及没有考虑指标权重范围的问题,提出基于模糊期望值法的模糊增强DEA模型。考虑到DEA模型适合将决策单元进行分类,同时制造技术需要进行风险评估的问题,提出采用改进故障模式与影响分析(FMEA)方法对筛选出的高效率制造技术进行风险评估,最终得到优选的制造技术。改进FMEA方法基于模糊数和灰色关联分析方法,考虑故障成本和维修难度以及各风险因子的权重,避免了传统将风险因子简单相乘的缺陷。以某半导体制造企业的晶圆切割制造设备选择为例,验证了所提方法的有效性。     

产品设计方案择优的语言群决策方法研究

针对产品设计方案择优过程中评价信息具有的主观性和不确定性问题,以及现有产品设计方案择优存在的不足,提出了一种基于二元语义信息公理的语言型多属性产品设计方案择优方法。该方法将各专家语言评价信息转化为二元语义形式并使用二元语义信息集结算子分别得到了产品设计方案群组二元语义决策矩阵和群组二元语义指标权重向量,确定了产品设计方案指标主、客观组合权重向量;依据信息公理思想分别计算了各产品设计方案的二元语义信息量并确定最优产品设计方案。研究结果表明,该方法能够避免语言型评价信息转换与集结造成的信息损失,对产品设计方案指标进行组合赋权能够全面反映主观和客观程度,产品设计方案决策过程计算简单、准确有效,具有潜在实用价值。     

权重信息不完全的产品绿色度综合评价方法

针对现有的产品绿色度评价方法不能处理不完全权重信息的不足，提出基于数据包络分析理论的绿色度评价方法。该方法首先对评价指标进行规范化处理，使规范化后的数据越大越好；其次建立只有输出指标且含有偏好信息的DEA模型，最后，利用交叉效率，建立交叉效率矩阵，并以平均交叉效率作为产品绿色度的量化指标。实验结果表明，该方法不仅能够处理区间数、序关系等形式的不完全权重信息，也能够处理完全确定及完全不确定权重信息的绿色度评价问题，且具有较好的鲁棒性、可操作性。     

基于平衡权重和改进TOPSIS的航空发动机装配任务优先度评价方法

为解决装配任务优先度定性评价效果差、多因素协调困难等问题,提出一种基于平衡权重和改进逼近理想解排序的装配任务优先度评价方法。依据任务属性的关联支配关系建立了综合评价层次模型,给出了指标量化方法;分别采用梯形模糊标度粗糙层次分析法、变异系数法确定主客观权重,建立主客观权重贡献趋于均衡的权重平衡模型以组合赋权;用Kullback-Leibler散度替代欧氏距离的改进逼近理想解排序来对评价对象的加权指标值进行评价并排序。通过实例应用验证了该方法的正确性和可行性。     

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.     

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.     

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.