占座效应的数学建模与统计分析

利用因果图模型及其可识别性理论对占座效应 ,即占座行为对座位使用率的影响进行了建模 .并利用这一模型对实际例子中的占座效应进行了分析 ,最终得出占座行为对实例中座位使用率的影响程度     

武汉市高校间公交线路的最优化设计

对武汉市高校间公交线路进行了设计.首先根据互访人数对25所代表性高校间的距离进行修正,采用聚类分析模型将25所高校划分为3类,分别以到达目的地所经过路程和线路总长度作为学生和公交公司的满意度指标,在每一类别内建立基于学生和公交公司满意度最大化的多目标优化模型,采用线性加权法将其转化为单目标优化模型并采用模拟退火算法进行模型求解.结果表明设计的3条公交线路长度适宜,学生到达目的地所经过路程结果较为合理.     

自适应蚁群算法及其在多约束多目标柔性Job-Shop调度中的应用

实际生产系统的车间作业调度一般是多约束多目标柔性Job-Shop调度,比经典的Job-Shop调度更复杂,存在多约束、多目标、动态柔性、建模复杂等特性.建立了多约束多目标柔性Job-Shop调度模型,提出了一种自适应蚁群算法,采用自适应机制和遗传原理防止算法过早停滞和加快收敛速度.西安航空发动机(集团)有限公司制造单元调度实例表明,提出的自适应蚁群算法是求解多约束多目标柔性Job-Shop调度的有效方法.     

海底管道分布浮力式侧向屈曲控制的多目标优化设计

基于弹性解析模型,提出了大尺度海底管道系统分布浮力式侧向屈曲控制的多目标优化设计策略,以满足管道系统侧向屈曲控制的不同性能要求.采用快速非支配排序遗传算法(NSGA-Ⅱ算法),对某分布浮力式海底管道浮力模块的设计参数及布置位置进行了优化设计,使侧向屈曲的位移和轴力控制达到最佳.算例结果表明,浮力模块的数量并不能对管道侧向屈曲的控制效果产生绝对的影响,通过多目标优化设计方法得到的Pareto最优集,可以为设计人员在海底管道侧向屈曲控制设计中兼顾多个性能需求以及选择更理性的设计方案提供参考.     

多尺度优势模糊目标决策系统的粗糙集、最优尺度选择及约简

多尺度决策系统的知识获取是当今的研究热点之一。然而,在处理实际数据时,多尺度决策系统中的条件属性值之间可能存在优劣关系,决策属性取值可能为模糊数。针对这一类多尺度决策系统的知识获取问题,本文构建了多尺度优势模糊目标粗糙集模型,给出了该模型的最优尺度选择算法,并讨论了获取所有最优尺度约简的分辨矩阵法和获取一个最优尺度约简的简便算法。最后将本文提出的多尺度优势模糊粗糙集模型、最优尺度选择和规则获取算法应用于计算机审计风险评估,得到较为合理的评估规则。     

多类型需求流的截流选址问题研究和算法实现

本文研究了网络上固定的O-D对上存在不同类型的需求流的选址问题。在基本截流模型的基础上提出了多类型需求流多目标截流选址问题的模型,将模型转化为多目标模糊规划问题,运用混合遗传算法求解模型,最后给出了算例,并与分支定界法相比,证明了混合遗传算法可以有效的求解此模型。     

基于改进自助扩容算法的弹药贮存可靠度评估

针对弹药试验数据样本量少时无法直接采用经典统计学方法的问题,介绍了弹药贮存可靠度评估的传统方法和现有自助扩容方法,并针对其不足提出了改进自助扩容算法,增加了自助样本量信息、保证了抽样样本与原始样本特征的一致性、降低了异常值的影响,并对所提算法利用Matlab软件仿真验证.结果表明,所提算法能有效进行贮存可靠度评估,具有显著优越性.该结论可用于弹药小样本数据贮存可靠度评估,为弹药贮存管理提供理论支撑.     

双混合整数目标规划生产经营计划模型及其求解

本文用混合整数目标规划建立了工厂(企业)的生产(经营)计划模型,并将目标单纯形法和分枝定界法相结合给出了一个算法。文中所研制的双混合整数目标规划模型和求解这一模型的计算机软件系统已用于制订某工厂年度和季度生产经营计划。得到的方案为该厂的生产和经营管理提供了科学依据,显著地提高了工厂的经济效益。     

基于人机交互—蚁群算法的港口疏船调度优化

为解决因港口无法正常作业导致大量船舶压港后的疏船调度问题,从同时兼顾船公司和港口方利益出发,建立了船舶平均在港时间最短、额外作业成本最低、生产秩序恢复最快的调度生产多目标优化模型。利用多属性效用理论将多目标转换为单目标,并构建了相应的评价函数,采用改进的蚁群算法并结合人机交互以及邻域搜索方法求解,最后以大连港集装箱码头实际案例进行验证。结果表明,与通常调度方法相比,文中建立的优化模型能够更好地解决疏船问题;对比常规的蚁群算法,改进后的算法搜索效率更高。上述模型和算法为集装箱码头的生产组织调度提供了新的优化思路和方法。     

基于遗传算法的座位优化控制模型

座位优化控制是航空运输界增加利润的有效方法 .基于旅客的需求预测 ,可以利用数学规划模型为不同的航段和票价组合计算座位销售上限或者销售竞价 ,从而达到单个航班收入最大化的目的 .常用的方法可分为确定模型和概率模型 ,但对多航段多舱位的优化问题 ,由于出现了复杂的组合和约束 ,这些模型必须简化 .提出了基于遗传算法的座位优化控制模型 ,并和常用的优化方法进行了仿真对比 .研究结果表明 ,遗传算法应用于座位优化 ,可得到满意的解 ,同时 ,遗传算法简化了复杂的约束关系 ,易于实现 ,具有明显的优势 .     

基于数字仿真的收益管理整合决策

对航空公司收益管理进行机票定价和座位存量分配的整合研究。应用计算机仿真算法动态构造民航收益管理系统中的需求预测模型,并根据航班收益最大化原则,确定价格与座位存量分配,根据需求变化实时调整价格和座位存量。仿真运算结果显示,该算法可以使航空公司不同航班收益比固定价格提高2%以上。     

Modeling of a vehicle seat suspension system with pneumatic spring and viscous dampers

The paper contains physical and mathematical model of the passive system of seat suspension, used in trucks and buses. Spring force in this system is performed by air spring, whereas damping force is generated by two viscous dampers. Based on the experimental research of characteristic parts of the suspension system, the parameters of mathematical model are determined. Both results of computer simulations and experiments are presented as power spectral density of acceleration courses, measured on seat, in comparison with courses measured on excitation platform in laboratory. Transmissibility of real system and its model are also presented in the paper. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stability study of the human body-seat system into an autovehicle

The paper presents the study of the human body, as a mechanical system, seated inside an autovehicle and exposed under the vertical harmonic vibration action during the auto vehicle motion time. The human body may be roughly approximated by a linear lumped parameter at low frequencies and low vibration levels. Therefore, the model has 5 DOFs in translation, where 4 DOFs represents the human body and 1 DOF is for the seat cushion The mechanical model of the human body, in sitting position on the seat cushion of a vehicle seat, consists of four parts: pelvis, upper torso, viscera and head.. The eigenvalues for the human body – seat system and the damping ratio for the system was been calculate. The system stability analysis is given by the existence of a Lyapunov function for the system. The stability of a system can also be characterized by the eigenvalues of the system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Modelling of working machines seat suspension with an air-spring and hydraulic shock-absorber

For the purpose of this paper, an exemplary seat suspension system is modelled and simulated numerically. The system consists of a shear guidance mechanism of a suspended seat, an air-spring, a hydraulic shock-absorber and end-stop buffers. As results of computer simulations, the power spectral densities of acceleration and the transmissibility functions of seat suspension are evaluated with respect to results measured experimentally. The verification of simulation model is performed in the basis of Seat Effective Amplitude Transmissibility factor (SEAT) and the maximum relative displacement of suspension system. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Active control of working machines seat suspension aimed at health protection against vibration

The paper presents the model and simulation of passive and active earth-moving machines seat suspension. The object of the simulation is the visco-elastic passive seat suspension with an air-spring, hydraulic shock-absorber and scissors guidance mechanism. Passive seat suspension amplifies the vibration amplitude at low frequency range of excitation signal (the resonance effect). In order to help the working machines operators against vibration, the active system with different control strategies is elaborated. Active system improves significantly the behavior of the seat suspension at low frequency excitation, with the most effectiveness obtained for the resonance frequency. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Neural network control of seat vibrations of a non-linear full vehicle model using PMSM

In this paper, the dynamic behaviour of a non-linear eight degrees of freedom vehicle model having active suspensions and passenger seat using Permanent Magnet Synchronous Motor (PMSM) controlled by a Neural Network (NN) controller is examined. A robust NN structure is established by using principle design data from the Matlab diagrams of system functions. In the NN structure, Fast Back-Propagation Algorithm (FBA) is employed. The user inputs a set of 16 variables while the output from the NN consists of f₁–f₁₆ non-linear functions. Further, the PMSM controller is also determined using the same NN structure. Various tests of the NN structure demonstrated that the model is able to give highly sensitive outputs for vibration condition, even using a more restricted input data set. The non-linearity occurs due to dry friction on the dampers. The vehicle body and the passenger seat using PMSM are fully controlled at the same time. The time responses of the non-linear vehicle model due to road disturbance and the frequency responses are obtained. Finally, uncontrolled and controlled cases are compared. It is seen that seat vibrations of a non-linear full vehicle model are controlled by a NN-based system with almost zero error between desired and achieved outputs.     

An efficient computational approach for railway booking problems

This paper deals with the determination of seat allocations for a rail booking system. It is assumed that demand for each trip in the network can be divided into two segments, namely a full fare segment and a discounted fare segment. A constrained nonlinear integer programming model is formulated to deal with this problem. The purpose of this paper is to develop an efficient heuristic approach to develop the booking limits for all ticket types in the railway network. The solutions obtained by the heuristic approach are compared with those found by the Lingo software and the DICOPT solver. Numerical results show that the proposed heuristic approach only require a small number of CPU time to obtain superior solutions.     

一种基于在线优化的排队系统分配策略

优化医院的病床分配可以有效地提高医院的管理水平.基于层次分析法建立了一套医院病床分配的评价体系,通过模拟多服务台的排队模型计算其综合评价指数.再以每天不同疾病对床位的优先级作为决策变量,引入虚拟函数f表示决策变量到综合评价指数的映射关系,对函数通过Matlab模拟及在线优化,从而确定使综合评价指数更高的改进分配方案.最后,以某眼科医院的实际数据,验证了模型和模拟策略的有效性.     

An option-based revenue management procedure for strategic airline alliances

An airline has to decide whether to accept an incoming customer request for a seat in the airplane or to reject it in hope that another customer will request the seat later at a higher price. Capacity control, as one of the instruments of revenue management, gives a solution to this decision problem. In the presence of strategic alliances capacity control changes. For the case of two airlines in the alliance and a single flight leg we propose an option-based capacity control process. The determination of booking limits for capacity control is done with real options. A simulation model is introduced to evaluate the booking process of the partner airlines within the strategic alliance, considering the option-based procedure. In an iterative process the booking limits are improved with simulation-based optimization. The results of the option-based procedure will be compared with the results of the simulation-based optimization, the results of a first-come-first-served (FCFS) approach and ex post optimal solutions.