随机工时下的多目标柔性作业车间鲁棒调度问题

针对工时不确定条件下的多目标柔性作业车间调度问题,采用2个不确定参数描述随机工时的波动程度和约束条件允许违背程度,将不确定条件下的柔性作业车间调度问题模型转换成确定条件下的鲁棒对等问题模型。在算法设计中采用全局非支配解集保存每代进化过程中产生的非支配解,并选择全局非支配解集中的个体参与变异操作。在交叉和变异操作之后,设计了一种基于变邻域结构的局部搜索策略。最后,运用该算法求解经典基准算例,验证了其有效性。     

加工时间不确定的柔性作业车间鲁棒调度方法

针对中小批量环境下加工时间不确定的柔性作业车间调度问题,采用冗余处理方法构建了以最大完工时间为目标的鲁棒调度模型。为降低算法的搜索规模和提高算法的求解速度,提出了顺序搜索机制,并设计两阶段遗传算法,分阶段获取冗余状态和最优结果。采用某柔性生产线的数据进行正交试验,优化了算法关键参数,并构建了柔性生产线仿真模型,对调度结果的鲁棒性和优化目标性能进行了分析。结果表明,该算法在目标性能和鲁棒性上都显著优于标准遗传算法,能有效处理加工时间不确定的柔性作业车间调度问题。     

订单不确定下双资源约束多装配线鲁棒调度

考虑生产过程中的订单不确定等因素,建立了以最大化交付满意度、最大化装配线平衡率及最小化完工时间跨度为目标的鲁棒调度模型,基于差分进化算法和粒子群算法提出了对模型进行求解的混合优化算法,并通过算例验证了混合优化算法求解该鲁棒调度模型的可行性和有效性。最后综合分析PTCN公司二厂多装配线生产车间的实际生产情况,将所建立的鲁棒调度模型和提出的混合优化算法应用于实际的多装配线生产过程,获得了较优的调度结果。     

鲁棒优化与多智能体协调的电梯群控调度

针对电梯群控调度过程中交通流不确定和优化求解复杂性的问题,提出一种混合鲁棒优化方法和多智能体协调的电梯群控调度方法。分析了电梯群控调度中的交通流不确定问题,建立了解决该不确定问题的电梯调度决策鲁棒优化模型。为了弥补模型求解复杂度过高的不足,进一步提出鲁棒优化和多智能体调度结合的混合调度决策方法。仿真结果表明,该方法能有效改善群控调度的性能,提高群控调度对交通模式的适应性。     

带缓冲时间的不确定性作业车间鲁棒调度研究

对机器故障下的作业车间鲁棒调度问题进行了研究。根据威布尔概率分布函数和故障浴盆曲线将不确定的机器故障转化为定量化的故障区间,建立带缓冲时间的性能鲁棒调度优化模型。用遗传算法求解该模型过程中,确立带缓冲时间的鲁棒解码规则,且交叉片段在整个父代中搜索与片段对等的基因,有利于扩大交叉范围。最后的仿真实验表明,优化模型保证了调度的鲁棒性,提出的改进遗传算法对问题求解的有效性。     

一类已知概率分布下的混合车间鲁棒调度问题研究

为解决一类产品生产需经上游作业车间的零部件加工和下游流水车间的零部件总装的调度问题,在研究生产调度文献的基础上,给出了混合车间调度问题;给出一类已知概率分布下的混合车间鲁棒调度方法,并建立鲁棒调度模型;采用遗传算法求解鲁棒调度模型。最后进行了实证研究,证明所建模型以及遗传算法在求解混合车间调度问题上是有效的。     

机器混合故障下柔性作业车间鲁棒调度方法

柔性作业车间机器在生产过程中时常发生退化故障和突发故障，针对这种混合故障，考虑用预防性维护来防止退化故障，通过插入缓冲时间的方式来吸收突发故障的影响。分别以工序最终完工时间期望值和各工序加工完成时间的延迟总和期望值为质和解的鲁棒性指标，建立柔性作业车间鲁棒性调度优化模型，并设计引入混合故障概率矩阵的改进遗传算法对模型求解，联合决策工序加工顺序、预防性维护位置和缓冲时间位置，同时优化调度方案的鲁棒性。最后通过数值实验与对比分析验证了此鲁棒调度方法能有效应对车间混合故障造成的扰动。     

任务工时不确定的模具车间前摄性调度研究

由于模具生产属于非重复性生产模式,各工序的工时具有很强的随机不确定性,这给模具车间制定合理可行的作业计划带来了一定的困难。针对这一实际问题,提出了一种考虑任务工时不确定性的前摄性车间调度算法。首先,分析了模具精加工环节的两道关键工序对制造系统稳定性的影响,并基于工序的工时不确定特性,建立了任务工时不确定的离散概率模型;然后,以调度方案的稳定度作为优化目标,构建了两阶段流水车间前摄性调度模型,针对该模型,提出了一种变宽集束搜索求解算法;最后,将该算法与定宽集束搜索算法进行对比分析,结果表明该算法能很好地兼顾求解质量和计算时间。     

面向能耗的多工艺路线柔性作业车间分批优化调度模型

合理的调度方案能有效降低柔性作业车间总能耗。针对柔性作业车间中加工工件种类多、单批工件数量大、加工工艺路线柔性大等问题,研究一种面向能耗的多工艺路线柔性作业车间分批优化调度模型。分析柔性作业车间中工件加工过程能耗特性,以车间总能耗最低和完工时间最小为优化目标建立了多工艺路线柔性作业车间分批优化调度模型,并采用多目标模拟退火算法对模型进行优化求解。通过算法优化得到的调度方案与经验调度方案的对比分析,验证了该模型的有效性和实用性。     

不确定环境下再制造加工车间生产调度优化方法

针对再制造加工车间工况兼具随机性与模糊性,采用模糊随机变量表示废旧件加工时间,以描述再制造加工车间工况的双重不确定性;在不确定理论的基础上,建立基于模糊随机机会约束的再制造加工车间生产调度问题模型,并提出求解该问题混合智能优化算法:基于Arena仿真平台应用模糊随机模拟技术产生输入和输出数据,利用粒子群优化算法训练径向基函数神经网络以逼近不确定函数,将训练好的神经网络嵌入至遗传算法中优化再制造加工车间生产调度问题;通过仿真实例验证该混合智能优化算法解决加工时间为模糊随机变量的不确定环境下再制造加工车间生产调度问题的有效性和合理性。     

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.     

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.