交通方式划分的非集计模型——以蚌埠为例

为研究影响城市交通结构的主要因素,建立出行者属性与个体出行方式选择的合理关系模型.所有的出行者相关属性数据均由统计资料获得,方式选择数据由蚌埠市居民出行调查的数据获得.应用非集计模型来建立个人属性、家庭属性和出行属性与方式选择间的函数关系.建模结果表明:居民出行交通方式选择与个人属性、家庭属性和出行属性之间有较稳定的关系,其随着时间的推移变化甚微.非集计模型所推算的交通方式结构较为精确,可用于交通方式结构的预测.此外,所建模型亦能识别方式分担的主要影响因素,从而实现交通方式结构优化.     

基于预算约束的多产品报童风险模型研究

对条件风险价值(conditional value-at-risk,CVaR)准则下多产品报童模型进行研究.建立了以产品利润的CVaR值之和最大化为目标,具有预算约束的多产品报童模型.根据产品边际预算CVaR值的单调性,采用二分搜索算法对模型进行求解.应用算例分析零售商的预算与风险厌恶程度对最优订购策略的影响,得到结果:随着预算及风险厌恶程度的增加,零售商订购产品的种类增加;零售商的期望收益是风险厌恶程度的减函数.     

应急救援物资车辆运输路线多目标优化

运用运筹学中图论及多目标优化的理论和方法建立应急救援物资车辆最佳运输路线的选择模型,并基于启发式算法求解该模型.从静态网络应急物资车辆运输路线的双目标优化问题入手,设计适合本文模型的算法,并将之推广至含有三个及三个以上优化目标的路线选择问题.引入时间扩展图的概念,将动态网络中的最佳运输路线问题转化为静态网络中的路径选择问题.算法实质是通过构造辅助决策函数实现Dijstra算法的调用,并在辅助函数构成的搜索空间上寻找最优解,是一种快速的、近似的算法.利用随机路网和真实路网测试本文算法,测试结果与本文的理论分析一致,证明本文算法在应急救援物资车辆运输路线的多目标优化问题中可行且有较好的应用效果.      

基于CPN炼钢连铸制造流程的建模与最优调度求解

应用着色Petri网对复杂的多阶段、多产品生产过程的炼钢连铸制造流程进行建模.该模型具有直观的图形表示、方便分析模型性质和仿真模型性能等优点.重点讨论了建模的两个关键问题:通过不同的运输变迁设置不同的看守函数实现路径选择;通过编制单体工序变迁的输入输出函数实现不同产品的不同处理时间.采用发生图验证了模型的有界性约束,并基于发生图提出一个求解最小makespan的最优调度方法.实例应用表明了该方法的有效性.     

多金属矿床边际品位优化与应用

为了有效利用稀缺的地质资源,建立了以净现值(NPV)为目标函数的矿床经济评价模型.采用盈利法计算伴生元素的当量品位,并基于三维数字矿床模型,分别以目标函数最大化和净现值大于0为目标,得出最优边际综合品位和盈亏平衡边际综合品位的计算方法.应用所建立的模型对某铜钼矿的边际品位进行了优化计算,优化结果可为矿山的投资建设和生产规划提供准确的经济分析,并保证资源的最优化利用.     

钢铁企业轧制计划与能源调度协同优化

钢铁企业物质流网络与能量流网络的协同优化是实现钢铁行业高层次系统节能的关键。钢铁企业在不同工况下煤气的富余量以及蒸汽和电力需求量不同，轧制工序(含加热炉)作为电力和煤气消耗大户，轧制计划的改变会影响能量流网络中能源介质的分配和调度。提出了钢铁流程物质流与能量流协同优化方法，在分时电价的条件下，利用启发式规则调度方法对一天内的轧制单元进行合理的排程，然后用线性规划方法以系统运行能源成本最小为目标函数，建立钢铁企业煤气 蒸汽 电力系统不同工况下的耦合优化调度模型。通过LINGO求解出模型的最优解，得到了轧制单元的最优排程以及不同工况下煤气、蒸汽、电力的最优实时生产调度方案，用于指导实际生产。利用S钢厂实际数据进行实例分析，得出的调度方案可实现煤气 蒸汽 电力系统的最优化分配，系统运行的能源成本降低8.54%，验证了模型的有效性。     

基于障碍函数内点法的防御武器配系部署建模与智能优化

针对防空任务中我方多平台、多武器、多区域部署带来的防御武器配系难以建模和实时优化难的问题，在考虑敌我双方攻防武器对抗博弈的条件下，提出了一种基于障碍函数内点法的我方防御武器部署优化模型，并综合武器防御效能、防御成本、保卫目标的资产价值等指标对模型进行智能优化解算与分析.首先，建立我方部阵地、防御武器与保卫目标的参数化模型，并建立我方武器对于敌方武器拦截的概率函数与约束条件；然后，将防御武器优化部署问题转化为性能指标函数为凸函数的无约束优化问题；最后，引入障碍函数内点法对其进行快速求解，给出了防御阵地武器部署的最优配置方案.所提方法充分考虑了来袭目标的不同类型、异构特性以及大气层内外防御的多元化火力运用方式；能够在具有混合整数非线性、约束强耦合、变量规模大等特征的防御武器配系场景下快速给出最优配置结果.并且，通过数值仿真验证了在对抗博弈条件下所提部署建模与智能优化方法的有效性与优越性.     

衡钢电弧炉炼钢流程能量的多尺度研究

摘要： 在建立不同铁水比例下的能量平衡与物料平衡的基础上,利用多尺度方法分析研究衡阳华菱钢管有限公司电弧炉炼钢跨尺度全流程能量的状况,主要包括工位级节能技术研究、余热利用技术、工位级间相互的关系与电弧炉炼钢流程集成技术。实现了跨尺度全流程能量的集成,得出最优能耗的冶炼生产模式。     

支持多租约SaaS应用按需服务的负载均衡策略

负载均衡是支持多租约SaaS应用实现可扩展性的关键技术.针对现有的负载均衡策略无法适应多租约SaaS应用按需服务特点的问题,提出了一种支持多租约SaaS应用按需服务的负载均衡策略.基于对租约用户个性化需求的分析,建立了面向租约功能类型的服务器负载模型.面向租约用户非功能需求提出了系统资源预分配规则和算法,并基于系统资源配置方案提出了基于租约用户限制的执行请求分配算法.实验结果表明所提出的负载均衡策略在满足了用户需求的同时有效提高了多租约SaaS应用的整体性能.     

应用需求时间窗的柔性作业车间调度优化模型

为解决拉动式生产模式下准时交货给生产调度带来的困难,提出了一种基于"需求时间窗"的柔性作业车间调度问题优化方法.首先,根据工件的需求时间窗口,构建了一种以工件完工时间平均隶属度最大为目标函数的柔性作业车间调度问题优化模型.然后,针对模型提出并设计了一种基于多阶段混合变异的禁忌搜索算法.为增强算法收敛性,利用"逆序变异"和"基因段交换变异"找到较好的初解,在此基础上利用"基因交换变异"继续搜索优解.最后,通过在某多品种小批量生产车间的应用验证了该方法有效性.     

Construction Congestion Cost (CO3) Traffic Impact and Construction Cost

The Construction Congestion Cost System (CO3) is an integrated set of tools to estimate impact of traffic maintenance contract provisions on congestion, road user cost, and construction cost. Engineers use CO3 to produce realistic budgets and select practical contracting methods that provide an acceptable balance between construction cost and congestion. This paper demonstrates computation of impacts associated with alternative methods of maintaining traffic during construction. The Routes Sheet computes equivalent average vehicle routes for complex diversion routes. The Input Sheet provides for documentation of vehicle and route inputs and computes user cost for individual trips through the work zone, diversions, and cancellations. The Traffic Sheet computes daily traffic impacts and user costs for each construction method. The Construction Sheet computes impact of different construction methods on construction costs. The Impact Sheet summarizes daily impacts and computes total project traffic impacts, road user costs, and construction costs for all alternatives. These tools provide practical information with which engineers select construction methods whose impacts are acceptable.     

Construction Congestion Cost (CO3) Basic Model

The Construction Congestion Cost System (CO3) is an integrated set of tools to estimate impact of traffic maintenance contract provisions on congestion, road user cost, and construction cost. CO3 produces realistic budgets and selects practical contracting methods that provide an acceptable balance between construction cost and congestion. This paper describes the underlying CO3 model of traffic demand, delay, and user cost, particularly the methods by which CO3 calculates traffic backup and delay, diverted and canceled trips, and road user cost. It provides examples that illustrate the CO3 model and methods. CO3 models the common characteristic of construction work zones by which road capacity can vary from hour to hour as lanes close and open and work conditions change. Traffic demand also varies with time of day, and drivers may divert to an alternate route or cancel trips because of delays caused by construction. CO3 estimates traffic delay due to traffic congestion as a function of demand and capacity, and it estimates traffic cancellations and diversions as functions of traffic delay.     

Multiobjective Transportation Planning for Waste Hauling

In the transportation planning for some industrial wastes, in addition to hauling cost, environmental impact must frequently be considered. A notable example is transporting waste soil generated by major construction projects. Adequate transportation planning is particularly important for construction in a metropolitan area. In this study, we present a novel two-phase approach to address the multiple-criteria decision problem. The first phase applies the fuzzy analytic hierarchy process to obtain a “composite impedance” for each road sector where transportation costs, environmental impact, and traffic congestion are considered in the evaluation. The second phase employs fuzzy mathematical programming to find the optimal transportation network based on the fuzzy impedance. An illustrative example is provided for the transportation planning for waste soil of the Kaohsiung mass rapid transit system construction project. The optimal solutions using the proposed approach are compared with the solutions using the conventional shortest-path approach where minimizing the transportation cost is the only objective.     

Minimizing Construction-Related Hazards in Airport Expansion Projects

Airport expansion projects often require the presence and movement of construction labor and equipment near critical airport traffic areas. This close proximity between construction activities and airport operations needs to be carefully considered during the planning of construction site layouts in order to minimize and eliminate all potential construction-related hazards to aviation safety. This paper presents the development of a multiobjective optimization model for planning airport construction site layouts that is capable of minimizing construction-related hazards and minimizing site layout costs, simultaneously. The model incorporates newly developed optimization functions and metrics that enable: (1) maximizing the control of hazardous construction debris near airport traffic areas; (2) minimizing site layout costs including the travel cost of construction resources and the cost of debris control measures on airport sites; and (3) satisfying all operational safety constraints required by the federal aviation administration as well as other practical site layout constraints. The model is implemented using a multiobjective genetic algorithm and an application example is analyzed to demonstrate the use of the model and its capabilities in optimizing construction site layouts in airport expansion projects.     

Traffic congestion, Type A behavior, and stress.

Conducted a quasiexperimental study to assess the effects of routine exposure to traffic congestion on the mood, physiology, and task performance of automobile commuters. Traffic congestion was conceptualized as an environmental stressor that impedes one's movement between 2 or more points. 61 male and 39 female industrial employees were assigned to low-, medium-, or high-impedance groups on the basis of the distance and duration of their commute and were classified as either Type A or Type B on the Jenkins Activity Survey, a measure of coronary-prone behavior. As expected, subjective reports of traffic congestion and annoyance were greater among high- and medium-impedance commuters than among low-impedance individuals. Also, commuting distance, commuting time, travel speed, and number of months enroute were significantly correlated with systolic and diastolic blood pressure. Contrary to prediction, medium-impedance A's and high-impedance B's exhibited the highest levels of systolic blood pressure and the lowest levels of frustration tolerance among all experimental groups. Results are discussed in terms of the degree of congruity between commuters' expectancies and experiences of travel constraints. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimizing Airport Construction Site Layouts to Minimize Wildlife Hazards

Construction operations in airport expansion projects often attract wildlife species to critical airport traffic areas leading to an increase in the risk of wildlife–aircraft collision accidents. Airport operators and construction planners need to carefully consider and minimize these wildlife hazards during the planning of construction site layouts in order to comply with Federal Aviation Administration recommendations. This paper presents the development of an advanced optimization model for planning airport construction site layouts that is capable of minimizing the hazards of wildlife attractants and minimizing the site layout costs, simultaneously. The model incorporates newly developed concepts and performance criteria that enable (1) quantifying, controlling, and minimizing the hazards of construction-related wildlife attractants near airport traffic areas; and (2) minimizing the travel cost of construction resources and the cost of devices installed to control wildlife on airport construction sites, while complying with all relevant aviation safety constraints. The model is developed using a multiobjective genetic algorithm and an application example is analyzed to demonstrate the use of the model in optimizing airport construction site layouts and its unique capability of generating optimal trade-offs between wildlife control and site layout costs.     

Effect of Common Cause Failures on Indirect Costs

Next generation bridge management systems will take into consideration multiple hazard scenarios and not only traffic loading and structural deterioration as they do now. The indirect costs used in these bridge management systems to determine optimal management strategies vary according to the hazard scenarios considered. The difference depends on whether or not the bridge failures are due to a common cause, such as a single flood or earthquake, or due to load events that may be considered statistically unrelated, such as truck loads. To illustrate the effect of common cause bridge failures on indirect costs, two examples are presented that treat the failures first as if they are due to statistically independent loading events and then as if they are due to a common cause. To examine the effect of bridge failures on indirect costs of the system, estimation is performed at the network level. The first example, on a simple network, shows the indirect cost estimate for all of the network condition states. The second example, on a complex network, shows the difference in the possible reduction of total indirect costs with a single bridge intervention as well as the change in intervention sequence. The main conclusions are that total indirect costs and optimal intervention sequences differ depending on whether or not bridge failures are due to a common cause, and that the largest changes in indirect cost estimation occur when simultaneously failed bridges affect the method of indirect cost incurrence.     

Sample Average Approximation Technique for Flexible Network Design Problem

Finding an optimal investment strategy to use scarce resources efficiently is challenging, since the transportation network parameters such as demand, capacity, and travel cost are uncertain. Sequencing investments over time can give flexibility to the planner so as to change, delay, or even abandon the future investment based on system realization. This paper presents a stochastic mathematical program with equilibrium constraints (STOCH-MPEC) formulation for a multistage network design problem, flexible network design problem (FNDP), accounting for demand stochasticity and demand elasticity. STOCH-MPEC problems can be computationally intractable, if the number of scenarios is large and/or the study network is large-scale. To reduce the associated complexity of FNDP, we develop a sample average approximate method (SAA) to efficiently solve the flexible network design problem. We implement the SAA on a test network and compare the performance of SAA with different sample sizes. We show that SAA can produce solutions that are close to the true solutions with considerably fewer scenarios and hence can be a viable computational technique for the stochastic network design problem.     

Approximation Techniques for Transportation Network Design Problem under Demand Uncertainty

Conventional transportation network design problems treat origin-destination (OD) demand as fixed, which may not be true in reality. Some recent studies model fluctuations in OD demand by considering the first and the second moment of the system travel time, resulting in stochastic and robust network design models, respectively. Both of these models need to solve the traffic equilibrium problem for a large number of demand samples and are therefore computationally intensive. In this paper, three efficient solution-approximation approaches are identified for addressing demand uncertainty by solving for a small sample size, reducing the computational effort without much compromise on the solution quality. The application and the performance of these alternative approaches are reported. The results from this study will help in deciding suitable approximation techniques for network design under demand uncertainty.     

浅谈建设工程清单计价与定额计价的差别和有效结合

本文通过对工程量两种计价方式的对照分析,阐明了市场经济条件下工程造价人员应将两种计价方式有效结合,灵活应用,以保证企业有能力参加市场竞争,合理确定工程造价。