模拟与数字调光在公路隧道照明中的应用

本文对在公路隧道照明系统中采用的模拟与数字调光的构成、功能、特性进行分析,可以为其他类似工程在选择调光技术方案时提供借鉴和参考。     

遗传算法在固定货架堆垛机拣选路径优化中的应用

固定货架的拣选路径优化问题是一个典型的TSP问题。以堆垛机拣选路径作为研究目标,通过计算货位点所在的坐标位置产生拣选点。运用基于顺序的遗传基因编码方式编制程序,对拣选路径进行优化。仿真实验和实际应用表明该算法能较快找到最优解,并有效提高系统运行效率。     

Using Simulation and Data Envelopment Analysis to Compare Assembly Line Balancing Solutions

This paper presents a technique for comparing the results of different assembly line balancing strategies by using Data Envelopment Analysis (DEA). Initially, several heuristics--which can be thought of as assembly line balancing strategies--were used to solve seven line-balancing problems. The resulting line balance solutions provided two pieces of information that were of particular interest: the number of workers needed and the amount of equipment needed. These two items were considered inputs for DEA. The different line balance solutions were then used as layouts for simulated production runs. From the simulation experiments, several output performance measures were obtained which were of particular interest and were used as outputs for DEA. The analysis shows that DEA is effective in suggesting which line balancing heuristics are most promising.     

Excel和AutoCAD在方案设计计算中的应用

针对设计《整立吊车方案》的计算需要,将Excel和AutoCAD运用于施工方案的设计中,使用这些工具做计算模拟工作,使施工方案设计工作量大大减少,施工计算的准确性也随之提高,这种应用同样可以适用于其它技术方案计算系统模型。     

Simulation modeling and optimization for ambulance allocation considering spatiotemporal stochastic demand

To ensure a timely response to emergencies, governments are obliged to implement effective ambulance allocation plans. In practice, an emergency medical service (EMS) system works in an uncertain environment, with stochastic demand, response-times, and travel-times. This uncertainty significantly affects ambulance allocation planning. However, few studies in this field adequately consider the effect of spatiotemporal uncertainty in demand, because it is difficult to measure it quantitatively. As a result, few analytic models capture the dynamic nature of an EMS system and, thus, the allocation plans they generate are not efficient in practice. Therefore, this study proposes a simulation-based optimization method for ambulance allocation. A simulation model is constructed to mimic the operational processes of an EMS system, and to evaluate the performance of an ambulance allocation plan in an uncertain environment. Gaussian mixture model clustering is used to derive the uncertain spatial demand. Then, the simulation generates emergency demand based on the obtained spatial distribution. A Gaussian-process-based search algorithm is used together with the simulation model to identify optimal solutions. To validate the proposed method, a case study is conducted using data on emergency patients in the Shanghai Songjiang District. Compared with the current plan adopted in Songjiang, the experimental results demonstrate that the delay time and frequency of the EMS system can be reduced significantly by employing the proposed methods. Furthermore, nearly 41% of the allocation cost can be saved.     

Secure smart grid communications and information integration based on digital watermarking in wireless sensor networks

As more and more wireless sensor nodes and networks are employed to acquire and transmit the state information of power equipment in smart grid, we are in urgent need of some viable security solutions to ensure secure smart grid communications. Conventional information security solutions, such as encryption/decryption, digital signature and so forth, are not applicable to wireless sensor networks in smart grid any longer, where bulk messages need to be exchanged continuously. The reason is that these cryptographic solutions will account for a large portion of the extremely limited resources on sensor nodes. In this article, a security solution based on digital watermarking is adopted to achieve the secure communications for wireless sensor networks in smart grid by data and entity authentications at a low cost of operation. Our solution consists of a secure framework of digital watermarking, and two digital watermarking algorithms based on alternating electric current and time window, respectively. Both watermarking algorithms are composed of watermark generation, embedding and detection. The simulation experiments are provided to verify the correctness and practicability of our watermarking algorithms. Additionally, a new cloud-based architecture for the information integration of smart grid is proposed on the basis of our security solutions.     

Heuristic solution procedures for a mixed-integer programming discriminant model

Mixed-integer programming models for the two-group discriminant problem appear to be more promising, in terms of accuracy, than are linear programming models, but at a substantial computational cost. This paper poses a particular mixed-integer model and suggests heuristics, based on linear programming, for obtaining suboptimal but “good” solutions to it. The heuristics are compared to the mixed-integer model using Monte Carlo simulation with Gaussian data.     

岩土边坡稳定性的遗传算法分析

非线性优化方法主要缺陷在于当边坡土层为非均质复杂条件时,无法保证搜索到安全系数的全局最小解,而只能搜索到局部极小解。基于遗传算法,建立了搜索岩土边坡稳定性分析最小安全系数和滑移面中心坐标与半径的数值方法。问题的可行解在变量搜索区间内搜索,包括滑弧的圆心坐标和半径。数值模拟结果表明,遗传算法搜索到的边坡稳定最小安全系数与理论解是一致的。     

数据网格技术在税务发票管理中的应用研究

税务系统发票数据电子信息分散存放在全国各个省市的服务器数据库中,数据量达到了海量数据,而各省市之间税务发票电子信息却相互隔离,在税务系统内部形成了一个个的税务发票电子信息"孤岛",对于跨地区使用的税务发票的大部分脱离了税务机关的监控;海量的发票数据信息没有得到充分的利用;社会公众缺乏统一的税务发票真假辨别平台,数据网格技术的引入给解决这一问题提供了新的解决方案。论文首先对当前阶段国内外税务系统信息化与发票管理的现状作对比,对税务发票实际管理的现状进行了分析,论述了数据网格技术在税务系统发票管理中应用的现实意义。其次,在研究了目前网格技术理论及成果的基础上,提出构建基于Globus和OGSA-DAI的税务发票网格系统(TIG)。最后论文对进行了异构数据库连接进行了模拟测试。     

物流人才培养存在的问题与对策

物流作为＂第三利润源泉＂对经济发展影响的作用越来越大,然而物流人才的缺乏成为物流业发展的颈瓶。用归纳法对物流人才培养方面存在的问题进行分析,并在此基础上提出了在制定切实可行的物流人才培养规划,构建特色鲜明的物流人才培养体系,实施中高层次的＂物流英才培养计划＂,改善大学物流人才培养办学条件,加强校企联合办学培养复合型物流人才等方面采取对策。     

库存系统仿真技术及应用

对库存仿真系统的理论和应用进行研究,介绍了我们开发的专用于库存系统仿真的软件ISim(Invertory System Simulation Software Package),举例说明了仿真系统在库存控制中的应用。     

Economic incentives and the demand for accounting information: Perspectives from medieval English finance

In this paper we examine similarities that medieval English finance bears to modern systems of national finance. First, the medieval system afforded economic incentives which invited potential abuse by self-interested parties; second, while proposed solutions to such abuses were both administrative and fiscal, the fiscal monitoring solutions were largely accounting in nature. We discuss several of the medieval abuses and their accounting-based solutions instituted from, roughly, A.D. 1200 to 1375. We conclude that many of the economic factors and competing relationships of constituent groups are remarkably similar in principle and application to today’s environment. By gaining a perspective on their historical bases, we can gain a richer understanding of current practices.     

基于FDS与Pathfinder的学生食堂火灾与人员疏散研究

为有效避免食堂火灾的发生,应用火灾模拟软件FDS和人员疏散模拟软件Pathfinder,建立模型对某学生食堂火灾进行数值仿真分析。根据模拟试验所得结果和数据,分析学生食堂发生火灾时烟气运动、温度的分布和能见度的的变化规律以及人员疏散情况。研究结果表明,该模型能够有效模拟分析学生食堂火灾情况;规范并完善食堂后勤管理和私人承包制度,合理设置报警及消防系统将能有效的预防食堂火灾的发生。     

基于仿真的备件消耗预测方法研究

针对目前装备备件消耗预测遇到的问题,文章提出基于仿真的备件消耗预测方法。首先分析了装备维修保障系统的结构和运行规律,在此基础上建立了面向仿真的装备维修保障模型,包括装备使用任务模型、装备系统模型、维修保障系统模型、使用与维修保障活动模型。借助SIMLOX仿真平台,结合案例想定对上述模型进行了仿真实现,得到备件消耗的品种和数量。     

城市新区规划仿真模型系统分析方法研究

通过应用系统动力学建立城市新区规划系统仿真模型,已成为新区规划的一种重要手段。从分析构建仿真模型过程中通常所采用的系统分析方法入手,阐明了该方法的一些不足之处,提出了一种改进型的分析方法,即系统反馈环分析方法,探讨了该方法的机理和可行性,并结合天津滨海新区空港加工区的案例,论述了该方法对仿真模型系统结构和行为模式的分析过程。     

Statistical aspects of simulation: an updated survey*

Abstract Practical statistical techniques for the design and analysis of simulation experiments are presented. These techniques are relevant in both discrete and continuous, deterministic and stochastic simulation. To generalize and interpret the simulation output the analyst can use regression analysis. This analysis allows for interactions among factors. Actually the regression model provides either a first-order or a second-order approximation to the complicated simulation model. To decide which system variants (parameter combinations) should be simulated, the analyst may apply experimental design theory. This theory makes the exploration of the simulated system much more efficient and more thorough. In the preliminary phase of the simulation experimentation special screening designs can be used to investigate hundreds of factors in relatively few runs. In stochastic simulation additional problems arise. There are several approaches for determining how to initialize a simulation run and how long to continue that run. These approaches result in a confidence interval for the estimated response. Both steady-state and transient behavior are examined. Special variance reduction techniques are briefly discussed; the use of common random numbers (identical seeds) is discussed in more detail.     

多点配送中心选址及求解蚁群算法

将多点配送中心选址问题(multi-distribution center location problem,MDLP)映射为扩展K-TSP过程并设计了改进的蚁群算法。为提高算法的求解性能,在蚂蚁的选择规则里加入了代价引导函数,使用2-opt策略优化可行解并优化了信息素的更新方式。仿真算例及算法对比表明,模型和算法可以有效地表达和求解MDLP。     

电子商务专业师资与实践教学环节存在问题对策研究

本文分析了高校电子商务专业人才培养现状,并结合西安翻译学院目前自身的办学条件,深刻剖析了电子商务专业人才培养过程中在师资力量方面存在专职教师年轻、经验少,而经验丰富的兼职教师又在不断减少、青年教师缺乏到企业锻炼、缺少对外交流等问题;在实验性教学、电子商务模拟实验室、校内实训条件、跨院合作方面、校企合作方面等存在的问题,并给出了相应的解决方案和对策。     

基于Flexsim的医药配送中心仿真应用研究

医药物流系统相对于其他物流系统而言具有一定的特殊性．医药配送中心的规划是一个复杂的系统工程,用传统的数理工具往往无法预测其规划过程中出现的各种瓶颈。Fiexsim作为针对离散物流系统进行建模和仿真的软件平台．是配送中心仿真研究的理想选择。文中以一个医药配送中心规划为例．对其规划流程和各个详细步骤进行了研究,并通过F1exsim软件仿真．为配送中心系统的规划改进提供决策的依据。