Wolfe法和Rosen法在给水系统参数估计中的应用研究

为了估计给水系统节点流量和节点水压参数,实时模拟给水系统的运行状态,本文建立了参数估计最小二乘数学模型.该模型是带等式、非负约束的非线性优化问题.利用Wolfe既约梯度法和Rosen投影梯度法求解优化模型,讨论了模型求解步骤,得出了Rosen投影梯度法中投影矩阵的快速计算方法.编制了求解模型的计算机程序,应用于实际给水系统的参数估计,估计的节点水压与实测节点水压的平均误差为1.35m,表明模型及其求解方法是可行的,且Rosen法的速度更快.     

基于Monte Carlo法的结构动力学模型确认

提出一种蒙特卡洛模拟(MCS)与多元回归分析相结合的有限元模型确认方法。采用基于动态响应面法生成的代理模型改进直接MCS,用一种逐步迭代的方式改进代理模型保证模型确认的精度。传统欧氏距离/马氏距离从不同方面描述了两点间距离,然而如果在距离准则中能够同时考虑两者则会更全面。在相关性分析过程中,综合欧氏/马氏距离的特点,采用了一种欧氏/马氏距离相结合的不确定量化方法(距离判别方法),并给出了基于此指标的迭代收敛判断准则。算例仿真结果表明:所提出的有限元模型确认方法和此距离判别方法的使用,能比较大地降低MCS的计算量并能得到满意的模型确认结果,迭代收敛的稳定性和精度都有了提高。     

磁性目标的单点模量测距方法

针对磁偶极子模型,提出了一种基于磁梯度张量信息的模量测距方法.该方法利用磁传感器阵列测量磁性目标的磁感应强度模信号、总梯度模信号和梯度张量模信号,从而求解阵列与目标之间的距离.本文介绍了一种十字型平面磁梯度张量测量系统,并推导了测距求解过程;根据测距模型分析了影响测距精度的因素;仿真与实验结果表明:该方法相比直接反演法,抗噪性能更好,受磁性目标姿态影响更小,更具有实际应用意义.     

多分配枢纽站最大覆盖选址问题

讨论了多分配枢纽站最大覆盖选址问题(MAHMCP),即要求每一条被服务的O-D流能够在规定的时间、费用或距离内从起点任意经过一个或两个枢纽站后到达终点,如何选择个枢纽站以使被服务的O-D流达到最大.由于是强NP困难问题,一般难以在满意时间内求解30个节点规模的问题.通过建立MAHMCP的改进模型,设计了求解该问题的禁忌搜索算法,经过基于澳大利亚邮政(AP)枢纽中心选址数据包计算实验,发现禁忌搜索算法在求解MAHMCP时具有很好的计算效果,并且相比分枝定界算法能够节约大量的计算时间.经计算,这一算法可以用来求解82个节点规模的中国航空枢纽港选址问题.     

考虑不确定性的医疗中心动态选址方法

考虑到医疗需求随时间动态变化而具有不确定性的特征,提出一种医疗中心动态选址方法。在该方法中,首先将选址规划期划分为多个阶段,使用指数平滑法对各阶段的医疗需求进行预测;进一步的,以整个规划期内患者与医疗中心的成本要求为目标,同时考虑医疗中心的容量限制、患者可接受路程距离的限制以及建设医疗中心的投资金额的限制,建立动态选址优化模型;通过使用Matlab求解该线性模型,可得到医疗中心的优化选址方案以及医疗中心与患者之间的分配关系。最后,通过实例分析表明了给出方法的可行性与有效性。     

一类多产品设施选址问题研究

对一类多产品设施选址问题进行了描述,通过分析得出该类设施选址问题可转化为分配问题,从而可通过匈牙利法对该设施选址问题进行简便地求解.最后给出了该类多产品设施选址问题的求解范例.     

校园超市选址问题

本文就校超市的超市销售计划及重选地址问题做出讨论,根据实际的问题考虑所给的数据和合理的假设以及调查数据,对问题一超市的销售计划,建立了线性规划模型,分别优化得到了超市A与超市B的较优的销售计划,并以此指导超市的进货计划：针对问题二超市的选址问题,我们分别考虑了距宿舍距离、宿舍人数及购买力对超市重建后的销售量的影响,我们采用了类平均法的思想对新建超市选址建立模型,并用此模型求解该问题,得到了一个新建超市的优化地址点：最后对选址模型采用数值逼近法进行了改进。     

Excel规划求解在设施选址中的应用

设施选址对于企业的生产运营非常重要,应采用科学的方法进行选址评价。线性规划常用于复合设施选址的成本因素评价,针对其常用求解方法——表上作业法计算繁琐的问题,提出利用Excel软件进行求解的一种方便快捷、易于操作的实用方法。通过具体选址实例详细阐述了采用该方法对模型求解的具体步骤和结果。     

基于顾客有限理性的自提点选址研究

针对最后一公里配送情形下顾客选择行为是否对自提点选址产生影响,研究了基于顾客有限理性的自提点选址问题。考虑顾客取货距离和自提点的吸引力,重新构造了顾客对自提点的分段效用函数。在此基础上,采用Erlang-B模型描述自提点拥堵情形,并用MNL模型刻画顾客的有限理性行为,构建了基于顾客有限理性的自提点选址模型。运用免疫算法、贪婪取走算法和上升算法求解模型,不同随机算例验证了算法的有效性。最后,通过分析一个小规模的算例,结果显示:顾客有限理性行为影响自提点选址方案,顾客理性程度、自提点处理容量、自提点运营总成本、自提点覆盖距离是自提点选址的重要影响因素。     

竞争环境中的截流选址与设计问题

研究了在竞争环境下同时优化选址和设计决策的截流选址问题。产生于网络路径上的顾客流按一定概率分布来选择各个设施,概率分布由设施服务台数量与偏移原路径距离共同决定。在已有竞争设施存在的情况下,通过选址和设计服务台数量的决策使净收益最大。采用一种带权重的贪婪算法来求解该问题,经过大量计算实验表明该方法求解质量和求解速度都比较理想。     

Joint Identification of Location and Dispersion Effects in Unreplicated Two-Level Factorials

Most procedures that have been proposed to identify dispersion effects in unreplicated factorial designs assume that location effects have been identified correctly. Incorrect identification of location effects may impair subsequent identification of dispersion effects. We develop a method for joint identification of location and dispersion effects that can reliably identify active effects of both types. A normal-based model containing parameters for effects in both the mean and variance is used. Parameters are estimated using maximum likelihood, and subsequent effect selection is done using a specially derived information criterion. An exhaustive search through a limited version of the space of possible models is conducted. Both a single-model output and model averaging are considered. The method is shown to be capable of identifying sensible location-dispersion models that are missed by methods that rely on sequential estimation of location and dispersion effects. Supplementary materials for this article are available online.     

The Treatment of Revenue Generation Effects of Facility Location

Facility location research has paid little attention to the revenue generation aspect of the location decision. However, the choice of facility locations can seriously influence the amount of revenue obtained through its effect on service factors such as delivery time and the compatibility of distribution systems. A discrete multi-facility model that analyzes tradeoffs between revenue implications and conventional cost considerations is presented. In this model, prices realized and quantities demanded are dependent on the selection of facilities to supply each demand center. The model is discussed from the standpoint of its potential application and is shown to have a number of practical advantages over the previous treatment of demand effects of facility location in the literature. This model is formulated as a zero-one linear program, and an exact algorithm for its solution is developed. The new algorithm is shown to be considerably more computationally efficient than a well-known code for zero-one problems. Further, the simplicity and shortness of the code required for this algorithm make it a readily available technique for users of the model. Possible modifications of the model and the algorithm are discussed to indicate the general applicability of this research.     

Numerical methods for optimal control of impressed cathodic protection systems

Some optimal control problems arising from impressed cathodic protection systems are considered. Our objective is to find the location of anodes and the current density on the anodes that yield an optimal potential distribution on the cathode. We present a simple formula for the linear model and a gradient algorithm for the non-linear model. Boundary element methods are employed for the numerical calculation.     

Inverse problem methodology and finite elements in theidentification of cracks, sources, materials, and their geometry ininaccessible locations

Inverse problem methodology is extended, through the more difficult geometric differentiation of finite-element matrices, to identify the location, material, and value of unknown sources within an inaccessible region using exterior measurements. This is done through the definition of an object function that vanishes at its minimum when the externally measured electric field matches the electric field given by an assumed configuration that is optimized to match measurements. The method is demonstrated by identifying the shape, permittivity, charge, and location of an electrostatic source through exterior measurement. The procedure is then extended to eddy current problems for the identification of the location and shape of cracks in metallic structures. An example demonstrates that when dealing with eddy current problems the least squares object function used by others has multiple local minima so that gradient methods have to be combined with search methods to identify the one absolute minimum. Procedures are also given for handling situations with no cracks and overdescribed cracks     

基于DEA/PEG的供应商绩效评价及选择方法研究

运用数据包络分析/绩效博弈法对供应商的绩效进行了评价,在综合考虑绩效、能力、区位及需求等因素的基础上建立了供应商选择的整数规划模型.最后通过实例对该方法进行了详细说明,从而提高了供应商评价及选择的可靠性.     

考虑温度梯度的模态应变能法海洋平台损伤检测研究

针对导管架式海洋平台,研究了海水温度梯度对结构整体损伤检测方法之一的模态应变能法的影响。以一个导管架平台为模型,考虑温度对钢材弹性模量的影响,建立了该平台在模拟的海水温度梯度下的有限元模型。通过使用模态应变能法对该模型进行损伤检测,总结了温度梯度对基于模态应变能法的海洋平台损伤检测的影响规律。结果表明温度梯度会使该方法损伤定位能力变弱,对结构冗余度越大的构件影响越大;同时会使损伤程度识别精度降低,构件结构冗余度越大、损伤程度越小,影响越大。     

The Plant Location and Technology Acquisition Problem

This paper presents an analytical approach for simultaneous optimization of the plant location, capacity acquisition and technology selection decisions in a multi-product environment. The proposed approach can be useful when there is considerable interaction between these structural decisions e.g., in global manufacturing companies. We present a formal definition of the plant location and technology acquisition problem and provide a mathematical model. We describe the analytical properties of the model, which lead to the development of a solution algorithm. Progressive piecewise linear underestimation constitutes the backbone of our solution algorithm. The arising subproblems are amenable to a dual-based approach. We report on a set of experiments that improved our understanding of the interaction among facility design decisions and showed that the computational performance of the proposed solution procedure is quite satisfactory.     

An Examination of Various Methods of Minimising Strain Gradients in 3D Embedded Strain Gauge Analysis

This paper is a review of different methods used to reduce the effect of strain gradients in experimental models with 3D embedded strain gauged transducers. A detailed analysis of various methods used in relation to research carried out on a prosthetic hip implant is investigated. The methods to reduce these gradient effects detail the importance of the selection of the most suitable 3D transducer pattern and establishing the locations on the model where strain gradients are least problematic. It is also shown that the use of large‐scale models helps minimise the effect a gradient may have on data. Another way of avoiding strain gradients is to use axisymmetric models and embed the gauges at the same radius in the model but at a different angular orientation from the central axis. The strain gradient across the 3D embedded strain gauge transducer can be reduced using the methods described here so that significant errors in the final tensor do not materialise.     

模糊优选理论在废旧危险品销毁场址选择中的应用

结合我军大批废旧危险品亟待销毁处理的实际,针对国内销毁场址选择经验缺乏的现状,利用模糊优选理论的评价方法,依据现行的弹药作业区安全技术规范,创建了废旧危险品销毁场址选择的评估模型.提取出10个评价指标作为场址选择依据,采用两两比较法确定各指标的权重,然后运用评估模型对某部废旧危险品销毁场3个备选场址进行综合评价,选择出最优的建设地点.通过工程实践和建成后的应用效果,证明了该模型可以有效地对废旧危险品销毁场地进行评价,对销毁场工程建设有一定的参考价值.     

Fuzzy Multi-Criteria Decision Making for Solar Power Plant Location Selection

Vietnam is one of Southeast Asian countries with a rapid GDP growth rate, ranging from 6.5% to 7% annually, leading to an average increase in energy demand of 11% per year. This demand creates many new opportunities in the energy industry, especially renewable energy, to ensure sustainable development in the future for the country with applications of solar energy growing at the present, and other opportunities to expand in the future. In Vietnam, thanks to favorable weather, climate, terrain characteristics and many preferential support policies, there are many great opportunities in the field of solar energy exploitation and application. Location selection is an important problem in all renewable energy projects. Therefore, the author proposed a fuzzy Multi-criteria Decision-Making Model (MCDM) model for solar power plant location selection in this study, and as a result, location 5 is the optimal solution. The contribution of this study is to propose a MCDM for solar power plant location selection in Vietnam under fuzzy environmental conditions.