串并联衰退系统的多目标预防性维护优化建模

以多设备串并联衰退系统为研究对象,通过引入失效率调整因子,整合优化维护成本率和设备可用度,建立了一种设备层的单设备动态预防性维护的多目标决策模型。在此基础上,给出了多设备串并联系统成组维护的优化建模,提出了系统层的非周期预防性维护规划的优化方法。在模型中提出维修时间窗的概念,为降低系统层总维护成本,根据维修时间窗对逻辑串联设备组的维护作业进行作业合并,并对逻辑并联设备组的维护作业进行作业分离。数值实例结果表明,与各设备独立进行预防性维护相比,该建模方法更经济,可为多设备串并联系统的维护决策提供有力的支持。     

一种基于设备运行的预防性维护与生产批量联合决策模型

为了最小化生产与维护总成本,以有限产能批量问题为基础,建立了生产批量与预防性维护的联合决策模型。为体现生产与维护之间的关联性,采用基于设备运行的预防性维护策略,以准确评估不同生产负荷对设备状态的影响。为解决维护周期小于一个生产周期的情况,假设一个生产周期内可进行多次预防性维护。采用Lingo对该非线性的联合模型进行求解,算例表明:与采用基于时间间隔维护策略的建模方法相比,所提模型在不同设备负荷水平和维护周期条件下可有效避免设备过度维护和维护不足的问题,降低生产与维护的综合成本,并使平均维护成本接近最优值。     

基于系统可靠性的生产与维护计划联合决策

为准确构建生产系统中批量生产与设备维护之间的关联关系,以并行机系统产能受限批量计划问题为基础,提出并引入基于系统可靠性的预防性维护策略与成组维护策略,建立了以生产与维护总成本最小化为目标的生产计划与预防性维护联合决策模型,从而在保证系统生产效益的前提下优化系统的维护频率、减少系统中生产与维护的总成本。模型的求解采用基于产能约束松弛的拉格朗日松弛算法框架,并设计了基于移动平滑方法的构造启发式算法,以获得问题的可行解并协同优化系统生产和维护计划。数值实验表明,该模型能充分发挥并行机的协调能力,有效避免设备过度维护问题,从而降低生产与维护总成本,所设计的算法具有较好的求解性能。     

带缓冲区的三设备串行生产系统动态机会维护策略研究

以采用周定周期预防维护技术并带有中间缓存区的三设备串行生产系统为研究对象,基于机会结余和组成本理论,运用动态规划方法,在组合优化的基础上,建立一种基于设备可靠性的三设备串行系统动态机会维护策略及决策优化模型.该模型克服了在当前生产系统中设备只有短期信息可用,而导致预防性维护计划制定的灵活性不足这一问题.数值试验结果表明,该模型能在控制维护成本的基础上提供有效的维护调度方案,为企业的设备维护管理决策问题提供了一种新的解决思路.     

基于可靠度限制的排污泵系统预防性维护建模

为了使预防性维护模型更符合实际情况,假设每次预防性维护后排污泵系统的失效老化速率减缓,在此前提下,提出了基于可靠度限制的预防性维护建模方法。利用排污泵系统可靠性限制的预防性维护策略,建立了寻找最佳预防性维护次数与最佳预防性维护周期的方法。为了验证建模方法的有效性,进行了威布尔分布实例的仿真实验,结果表明提出的建模方法是可行和有效的。     

基于Markov过程的两级污水排放系统的预防性维护建模

为了提高两级污水排放系统的可靠性,将故障率较大的污水泵构建成冷备子系统,运用Markov过程建立了系统的预防性维护模型。以最大化系统可用度为目标,求解了各级设备的最佳预防性维护频率,进而分析了系统的稳态概率及状态间的转移概率,并采用策略迭代算法求得最佳维护策略。实验结果表明,所提出的建模方法与求解方法对研究多机系统的可靠性问题是有效、实用的。     

质量驱动的两设备串行再制造系统预防维护

针对再制造环境下的两设备串行系统，集成正常产品流与回收产品流，构建产品质量与设备质量部件衰退的交互作用模型，进而引入回收产品数量变化导致的设备生产率变化对设备衰退的影响机制，建立质量驱动下集成可变生产率的设备故障率模型，在此基础上提出基于成本节约的串行生产系统动态机会维护策略并进行决策建模。算例分析表明，该模型能够有效降低系统的维护成本，其可为再制造企业的维护管理提供技术支持。     

多设备串行系统预防性维护的动态决策优化研究

串行系统是目前工业界非常善盘的一种生产系统,而合理的预防性维护是保证串行系统可靠性的重要手段之一.本研究旨在探讨串行系统的整体预防维护策略及优化方法.通过采用动态规划方法,以及对设备维护成本、停机成本和惩罚成本的定义,建立了一种多设备串行系统预防性维护的动态决策优化模型.并以满足威布尔分布的三设备串行系统为例,给出了详细的决策步骤和优化站果.仿真结果显示,该模型满足设奋只有短期信息可用的实际操作特点,可为多设备串行系统预防性维护计划的制定提供有力的支持.     

带缓冲区的设备预防性维护优化建模

为提高设备的可靠性,提出带缓冲区的设备预防性维护优化建模方法。找出设备预防性维护的最优维护时刻点,以维护时刻点作为随机变量建立期望成本模型。在此基础上,构造求解最优维护点的演化算法,同时给出相对应的优化计算流程。通过多参数的敏感性分析确定了最优维护时刻点与相关参数间的相互关系,结果表明所提建模方法是有效且实用的。     

产能导向的三设备混联系统预防维护决策

为提高制造系统产能,建立了一种基于三设备混联制造系统产能失效率的预防维护模型。基于通用生成函数,综合考虑三设备串并混联制造系统中各设备的失效率、产能配比和配置型式,构建系统产能失效率模型,进而以最大化产能导向的混联系统开动率为目标,建立融合设备失效率阈值、系统产能失效率阈值和机会维护阈值的系统机会维护策略与决策模型。算例分析表明,该维护模型可量化解析因设备失效而影响系统产能的内在机理,有效保障系统产能。     

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.