不确定环境下模具制造项目群随机调度

为确保模具按时交货,通过分析模具制造项目工期、费用与报酬的不确定性,以及项目返修频繁的特点,建立了基于离散时间马尔可夫链的模具制造项目群随机演化模型,并提出了求解该随机动态规划模型的算法框架.通过启发式策略仿真和Q学习,有效解决了"维数灾难"问题.最后结合示例阐述了该算法的执行过程,及其可行性与可靠性.     

考虑返修的模具剩余工期估计

模具生产过程中充满了不确定性,尤其是返修的工序和次数不确定,使得准确估计和控制模具的生产周期成为一个世界性难题。为了解决这一问题,分别采用考虑返修的串联和混联制造排队系统来描述模具制造过程,在假定订单按先到先服务(First come first served,FCFS)规则进行加工且正常加工和返修时间均服从负指数分布的情况下,分析制造排队系统基于事件的状态转移过程和事件间隔时间,提出了返修强度的概念并将事件间隔时间近似为负指数分布,在此基础上结合独立伽马随机变量之和推导出模具剩余工期的近似数学分布模型。设计计算实例,将不同返修强度和初始状态下的数值计算结果与仿真结果进行对比分析,验证了剩余工期近似模型在不同返修强度环境下均具有良好可靠性。     

带随机返修的模具项目制造成本监视方法研究

模具制造过程的诸多因素导致其项目制造成本难以准确估计,尤其是模具返修成本的不确定性。为此,对带随机返修的模具项目制造成本监视方法进行了研究。首先,分析了造成模具项目成本不确定的诸多因素,并建立了基于返修事件的Markov链项目成本演化模型,考虑了返修成本的不确定性;其次,基于项目实际情况,提出了修正矩阵的方法对返修概率进行修正;最后,开发出了一个用于监视轮胎模具项目成本的系统,并结合实例验证了该模型的有效性和实用性。     

制造协作组织形成过程任务性能参数逆向优化

深入分析了制造协作组织形成过程的市场特性。针对产品制造任务性能参数的优化问题,提出正向优化与逆向优化过程模型,分析双向优化结构的宏观与微观特征。通过探讨可以发现,制造任务优化与制造资源配置是市场协作制造过程中的两个相互影响、密不可分的整体。通过针对逆向优化过程的研究,进行制造任务性能参数逆向优化过程的形式化描述,进一步构建任务参数优化的数学模型,并且运用矢量范数理论对模型的最优解存在性质进行论证。最后,在分析遗传算法的宏观与微观策略的基础上,利用基于实数编码的遗传算法对优化模型进行求解,用实例验证了优化方法与算法的有效性。     

基于产品特征的质量成本研究

传统企业在进行质量成本控制时,往往关注于容易量化的预防鉴定成本,而忽略了制造过程中报废、返修等内、外部故障成本。通过对制造过程中零件报废与返修的成本分析,建立了内部故障成本模型,然后根据产品特征,结合成本模型,分析了关键工序对成本的影响,提出了分层质量控制的思想。     

基于模型集的面向绿色制造工艺规划策略研究

分析了制造过程的输入，输出，揭示了面向绿色制造工艺规划的内涵，建立了面向绿色制造的工艺规划多目标优化决策总体模型，通过对该模型的分解，构造出面向绿色制造的工艺规划模型集，基于研究建立了一种基于模型集的面向绿色制造工艺规划策略，并开发了相应的面向绿色制造工艺规划的应用支持原型系统。     

面向生产制造过程企业伙伴协作研究

如何从盟主企业的主生产计划出发来有效控制合作企业的生产过程,是企业实施动态联盟的关键技术之一。研究面向生产制造过程企业合作伙伴的有效控制问题,基于任务分解与协作层次模型,建立了面向制造过程的多任务多级协作的图论模型,解析了任务节点的划分与控制,通过计算路径长度,确定协作网络中的关键路径,并对协作过程进行评价和决策。     

寿命型设备的预防维修策略研究

为解决寿命型设备在基于可靠度的预防维修下的经济维修策略问题,提出一种基于可靠度和经济性求解维修周期和维修时间策略的方法.基于可靠性理论,用维修度(维修时间的函数)近似描述维修降低的不可靠度比例,以可靠度和维修度服从指数分布为例,引入失效率递增因子和维修率递减因子,建立了设备可靠度与维修周期、维修时间的函数方程.基于该方程,以设备使用寿命内总收益为决策目标.建立了寿命型设备的预防维修周期和维修时间的策略模型.经优化计算得到不同参数下的预防维修策略.结果表明,寿命型设备的预防维修周期和维修时间呈先增长后缩短的趋势,且维修成本越高,维修次数和时间均越少.     

任务负载竞争下制造资源配置的非合作博弈方法

在制造资源配置过程中,针对不同生产设备为了追求任务负载而存在的自由竞争关系,引入博弈论描述设备之间在任务负载上的相互制约关系。提出基于非合作博弈的制造资源优化配置方法,把生产设备映射为非合作博弈制造资源优化配置模型的局中人,建立局中人的策略及其收益函数。利用模糊聚类分析的方法对博弈局中人进行聚类,进行Nash均衡的求解。通过实例与遗传算法、禁忌搜索、粒子群算法进行比较,结果表明基于非合作博弈的制造资源优化配置方法获得的任务负载策略能够保证生产设备总体具有更高的利用率,由此,验证了算法的有效性和正确性。      

面向时序约束任务的协同制造链构建过程研究

为实现制造任务的多企业协作,基于协同制造链的概念建立了时序约束任务有向图模型,系统研究了协同制造链构建过程的数学建模问题,分析了规范型与非规范型协同制造链的构建过程及其特点。通过对协同制造链的不同构建模式的分析,有助于实现多企业间制造任务的协作。     

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...     

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。     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.