基于近似动态规划的模具项目调度

模具制造工程中普遍存在任务工期不确定,以及多并行项目共享和竞争企业有限资源的情形,目前尚缺乏求解这类项目调度问题的方法。鉴于此,考虑了部分任务工期服从已知离散分布下的模具项目调度问题,基于马尔可夫决策过程理论构建了以总加权拖期成本期望最小为优化目标的数学模型。针对传统随机动态规划在求解大规模问题时面临的维数灾,分别提出了基于经典优先规则、遗传算法和近似动态规划的求解方法。通过随机生成的项目算例验证了所构建模型和方法的有效性。结果表明,所提近似方法能够在耗费较少计算资源的情形下获得可接受的次优或最优解,可用于求解工程实际问题。     

随机环境下模具企业车间负荷控制方法

针对目前难以对模具车间生产进行有效控制的问题,建立了多级车间任务投放控制模型。首先,考虑任务工期和资源需求的不确定性,分析了任务投放策略,构建了负荷中心直接和间接负荷的计算方法;然后,针对负荷过载问题,分析了模具车间生产能力调整策略,进一步建立了外协任务优化选择模型,并设计了混合优化算法进行求解;最后,通过实例分析说明了所提方法的实用性。     

不确定环境下模具群项目计划制定方法

针对模具项目群制造过程的不确定性和资源需求的动态性,建立了基于离散时间Markov的模具制造项目随机演化模型.基于该模型,提出一种分阶段求优的模具项目计划制定方法,将项目群的每一个任务视为一个独立的阶段,以最小化每个阶段的完工时间为目标,利用动态规划方法对每一个阶段的任务求解最优的调度策略.通过仿真算例将该方法与三种启发式算法进行比较分析,结果表明该方法在不确定环境下制定模具项目群项目计划时具有明显的优越性.     

多属性的虚拟企业并行协商项目规划算法

制订基于协商的虚拟企业项目规划不仅要考虑任务时间与工期的可行性,而且要关注费用与资源的优化。 通过分析虚拟企业项目协商规划的工期与费用的不确定性,首先提出了多属性随机项目模型;接着提出了工期- 费用并行协商规划算法,以期望工期费用为优化目标,结合示例解释其计算过程;最后针对模具生产的特点,对 模具虚拟企业的项目进行仿真规划,说明了这一方法的有效性和可靠性。     

具有一般工期与返工的耦合设计任务评审策略分析

为了有效评价具有一般工期与随机返工的耦合设计任务评审策略,基于相型分布和连续时间马尔可夫链构建了项目完工时间概率分布估算解析模型。分析了两种基于平方变异系数的一般分布近似方法,选择其中一种更高效的方法对任务常规工期和返工工期进行近似,将任务执行相位视为虚拟任务进行项目网络转换;利用连续时间马尔可夫链描述转换网络的执行状态转移过程,并利用相型分布计算项目完工时间概率分布。以一类典型模具设计项目为例进行计算实验,分析多种项目环境参数对评审策略表现的影响,并通过模具设计项目案例分析验证了模型和方法的有效性。     

基于改进微粒群算法的模具多项目动态调度

针对模具多项目执行过程中任务拖期导致的调度计划变更,提出了一种启发式动态调度算法.利用改进的微粒群算法构建一个加权工期之和最小的初始调度计划,并基于关键链管理方法对初始调度计划进行合理地缓冲设置.建立了以调度计划变更费用最小为优化目标的启发式动态调度模型,并用改进的微粒群算法进行求解.通过仿真计算分析了算法的町行性与可靠性,并与标准的微粒群算法进行了比较.     

随机生产环境下的模具制造单元资源配置

通过分析模具的生产需求情况,提出了一种模具聚类指标,应用聚类算法构造了几类典型的模具范例.通过资源静态与动态配置手段,提出了一种制造单元资源配置优化策略.针对模具生产的特点,以最小化期望工期费用为优化目标,提出了一种基于资源选择决策模型的改进型蚁群能力平衡算法,并通过生产实例,说明了该方法的可靠性和有效性.     

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.     

基于部件接口矩阵和设计结构矩阵的机电产品研发项目规划方法

研究分布式、多组织参与环境下机电产品研发项目的规划问题，提出了一种基于部件接口矩阵的粗规划和基于设计结构矩阵的细规划相结合的项目规划方法。根据待开发产品的部件接口关系定义接口矩阵，采用接口数量优先的原则进行变换，形成关联部件聚集的接口矩阵，实现项目粗规划；根据任务的时序约束将接口矩阵转换为设计结构矩阵，通过设计结构矩阵下三角化，将任务群分解成独立任务、解耦任务和耦舍任务，实现项目细规划。仿真和案例分析结果表明：在部件的接口关系较为松散的时候，粗规划可以把部件集分解成规模明显减小的独立部件子集；细规划把任务群分解成独立任务、解耦任务和耦合任务后任务子群的规模明显减小。     

多属性虚拟企业部分并行协商项目规划

在虚拟企业环境下,制定基于盟主与合作伙伴协商的项目规划不仅要考虑任务时间与工期的可行性,而且要关注工期费用。在分析虚拟企业项目协商规划的工期与费用的不确定性的基础上,提出了多属性工期一费用随机项目模型,以及工期一费用部分并行协商规划算法,以期望工期费用为优化目标,结合示例阐述其计算过程。最后针对模具生产的特点,对模具虚拟企业的项目进行仿真规划,仿真结果表明了这一方法的有效性和可靠性。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.