基于iSIGHT的鼓式制动器多目标优化设计

以鼓式制动器效能因素最大和制动鼓体积最小为目标,对鼓式制动器进行多目标优化设计,利用iSIGHT集成的多目标优化遗传算法,得到多目标优化问题的Pareto最优解集,再利用Pareto最优解集专用后处理工具EDM,找到最合适的折衷解.     

基于非支配排序遗传算法的变速器多目标优化设计

以某新型货车变速器为研究对象,基于多目标遗传算法和有限元法,建立其多目标优化模型,包括优化数学模型和参数化的有限元模型,以多学科优化软件iSIGHT为平台,集成有限元软件ANSYS,使用基于Pareto最优概念的非支配排序遗传算法,寻求变速器在最小体积、最大传动总重合度和最小中心距目标下的最优结构设计方案,并获得了问题的Pareto最优解集.文中提出的分析方法能够有效地解决复杂结构的多参数多目标优化问题.     

Pareto多目标遗传算法及其在机械健壮设计中的应用

在机械或结构的优化设计中 ,普遍存在约束的作用 ,且最优解往往位于可行域的边界上。由于外界环境的变化或人为因素造成设计变量扰动 ,可能使设计成为不可行。本文提出了一种的基于设计变量敏感性的健壮性设计方法 ,并提出了一种用 Pareto遗传算法来实施的带约束的多目标优化方法以求解健壮性问题。 Pareto遗传算法可得到 Pareto最优解集 ,从中可选出满足设计需要的解。本文提出的算法包括 5个基本算子 :选择、变异、交叉、小生境技术、Pareto集合过滤器。文中用算例说明该方法的应用     

基于Pareto遗传算法功率分流式无级变速器齿轮系多目标优化设计

以某功率分流式无级变速器为研究对象,在变速器结构已确定的情况下,并保证齿轮强度的基础下,对功率分流式无级变速器建立以速比范围最大、体积最小和轴中心距最短的齿轮系多目标优化数学模型,将Pareto最优解概念与遗传算法相结合,应用Matlab优化工具箱进行联合优化计算,获得了该问题的最优解集,结果表明,文中提出的方法能够有效地解决多参数多目标的优化问题。     

基于多目标遗传算法的直升机总体参数优化设计

应用多目标优化问题中Pareto最优解集的概念,提出了一种基于多目标遗传算法的直升机总体参数优化设计方法。算法引入了个体的序和密度的概念,改进了变异操作算子,使用精英策略,确保能够搜索到具有较高贴近性、均匀性和完整性的Pareto解集。以UH-1H直升机为优化算例的计算结果表明:多目标遗传算法适用于解决多目标优化问题,能够改善Pareto解的质量和均匀性分布。     

响应面和多目标遗传算法结合的副车架优化

为实现副车架设计过程中,质量和第一阶模态频率同时达到最优,在模态分析和三种工况副车架强度分析的基础上,首先应用Hyperworks进行了副车架参数化,建立了11个厚度尺寸变量。然后应用试验设计分析方法对尺寸变量进行筛选,去掉了3个对质量、最大应力和第一阶模态频率影响都不显著的因子,将基于移动最小二乘法构建响应面近似模型引入到副车架优化设计的复杂系统中。最后,基于副车架近似模型利用多目标遗传算法进行多目标优化,获得了副车架质量和第一阶模态频率的Pareto最优解。研究结果表明:通过获得的Pareto最优解的边界,可以指导副车架优化设计,将大幅缩减产品开发周期、降低产品开发成本。     

超薄平板塑件注射成型质量多目标优化

将翘曲度、平面度、尺寸精度作为超薄平板塑件质量管控目标,基于Kriging方法建立了各质量目标与工艺变量之间的数学模型,并采用NSGA-II(非支配排序遗传算法II)遗传算法获得质量多目标的Pareto解集,然后通过Vague评估方法,在Pareto解集寻求满足设计要求的最优解,实现了超薄塑件成形质量的多目标优化。将优化过程应用于超薄导光板生产实践,大幅度提高了产品成型精度,增强了生产过程的稳健性,证实了优化过程的正确性与有效性,为超薄塑件的生产实践提供了可靠的理论方法。     

火炮身管-反后坐装置集成优化设计方法研究

为减小火炮发射时的后坐阻力,同时减小火炮身管质量,以节制杆结构参数、身管结构参数和内弹道装药参数为设计变量,以身管刚度、强度、寿命、弹丸初速等为约束,建立火炮身管-反后坐装置集成优化设计模型,并采用两种优化方法进行优化,再比较其结果。首先,采用加权组合法将两个目标函数归一为单个目标,应用模拟退火算法进行优化设计,优化后,后坐阻力减小53%,身管质量减小28%。其次,基于Pareto最优理论,采用遗传算法进行优化设计,获得了Pareto最优解集,给设计者提供了更多优化方案;根据工程经验,选取一组优化解,结果发现,对比原设计,后坐阻力减小504%,身管质量减小98%。研究表明,基于Pareto最优理论和遗传算法可以获得更好的优化方案。该研究提供的集成优化模型和算法为火炮身管-反后坐装置一体化设计提供了新方法。
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基于iSIGHT平台的主轴箱多目标优化设计

针对工程实际中复杂的多目标优化设计问题,常遇到性能目标与设计变量之间不具有显式的函数关系式,难以直接运用优化方法进行设计计算,因此提出基于i SIGHT平台的多目标集成优化设计方法。以主轴箱多目标优化设计问题为例,在i SIGHT平台上集成ANSYS软件并进行建模和分析,采用响应面法构建近似模型,利用邻域培植遗传算法获得多目标优化问题的Pareto最优解集,根据工程实际的不同需求,从中选出最合适的优化方案。     

基于多目标遗传算法的贝塞尔超声变幅杆优化设计方法研究

为设计满足蜂窝复合材料加工要求的高性能超声变幅杆,提出了一种基于多目标遗传算法的超声变幅杆优化设计方法。以变幅杆的结构参数为设计变量,以谐振频率和放大系数为优化设计目标,建立了贝塞尔超声变幅杆的数学优化模型。通过在遗传算法中调用ANSYS仿真软件,对变幅杆进行了建模和动力学分析,获得了计算目标函数所需的参数,采用多目标遗传算法求出了Pareto最优解集,在所求出的Pareto最优解集中选择了一组最符合设计要求的解作为超声变幅杆的设计参数。为验证设计的有效性,对所设计的变幅杆进行了性能测试并对蜂窝复合材料进行了试切实验。实验结果表明：通过该优化设计方法得到的变幅杆放大倍数为7.66,较优化设计前提高了29%,且工作频率更接近于设计频率。通过仿真分析和性能实验,验证了该方法的有效性和可靠性,试切实验结果表明所设计的变幅杆满足加工要求,工艺效果好。     

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.