Data center supply chain configuration design: A two-stage decision approach

Data centers are special-purpose facilities that enable customers to perform cloud based real-time online transactions and rigorous computing operations. Service levels of data center facilities are characterized by response time between query and action, which to a large extent depends on data center location and data travel distance. Another aspect of service level is resource up-time availability, which is determined by data center configuration. Data center location and configuration decisions are, therefore, of great significance to ensure uninterrupted operations in customers of manufacturing and service industries relying on cloud-based computing resources. In this study, following a grid-based location approach, we present two mixed integer linear programming models for capacitated single-source data center location-allocation problems. The first model provides optimal locations, capacities and configurations of data centers, and allocation of demands to open facilities when there is no existing facilities in the region. Our second model considers the decision problem of meeting new demand when the existing demand is met by the already opened facilities. We term these newly arrived demand as replication demand, which results either from emergence of new users of existing customers at distant locations in the future, or as a means of increasing data resilience by creating data replication as a backup. To solve the decision problem for meeting primary and replication demand optimally, we propose a two-stage decision algorithm. The algorithm provides optimal locations, capacities and configurations for new data centers, capacity addition decisions to the existing facilities and subsequent allocation of demands. Both models and solution algorithm are implemented using AMPL programming language and solved with CPLEX solver. The models are found to be scalable and capable to provide high quality solutions in reasonable time.     

The location of public services considering the mode of travel

By reason of their generally longer travel times, transit users are not so well-served by many public facilities as are automobile drivers. This paper investigates the implications of this fact for the location of a specific type of service, public child day care. A location-allocation model is employed to determine the most accessible locations for a set of centres in Edmonton, Canada, for users of both modes. Transit is found to be capable of providing only 51% of the accessibility of the automobile, at 2.4 times the average travel time. The argument is advanced that in order to reduce the inequality of service to a minimum, public facilities should be located with the accessibilities of transit users in mind. The optimal systems are compared with Edmonton's present system which is found to be spatially inefficient and quite discriminatory in its inefficiency against transit users. This is attributed to the city's piecemeal planning policy and an inadequate understanding of the notion of accessibility. The paper concludes by recommending improvements which would improve our simple diagnostic model to the level of a useful planning device.     

Improving access to health facilities in Nouna district,Burkina Faso

The Nouna health district in Burkina Faso, has a population of approximately 275,000 people living in 281 villages, and is served by 25 health facilities, as of 2006. For many people, the time and effort required in traveling to a health facility, which may demand a journey of many kilometers over poor roads on foot, is a deterrent to seeking proper medical care. In this study we examine how access to health facilities in Nouna may be improved by considering the configuration of the road network in addition to the locations of the facilities. We model the situation as a facility location–network design problem and draw conclusions about how best to improve the physical access of the health facilities. Our model shows the extent to which access can be improved when the road network is considered along with facility locations, in contrast to facility locations considered alone.     

A multiobjective modeling approach to locating incinerators

The location of hazardous material incineration facilities is an important problem due to the environmental, social, and economic impacts that they impose. The costs associated with the facilities and the risks placed on nearby populations are important concerns as are the distributions of these costs and risks. This paper introduces a mixed-integer, multiobjective programming approach to identify the locations and capacities of such facilities. The approach incorporates a Gaussian dispersion model and a multiobjective optimization model in a GIS-based interactive decision support system that planners can access via the Internet. The proposed approach is demonstrated via a case study in central Portugal where the national government has decided to locate a large facility for the incineration of hazardous industrial waste. Due to intense local and national opposition, construction of the facility has been delayed. The system has been designed so that it can be used by decision makers with no special training in dispersion modeling, multiobjective programming, or GIS.     

探究轨道交通制造业存货采购可追溯性

目前,我国正处于社会主义时代的重要转型期,轨道交通的建设及发展成为了我国制造业中十分重要的行业。存货采购的可追溯性对于该产业的发展有着决定性的影响。因此,文中以轨道交通制造为前提背景,在国内外有成果的基础上,对轨道交通制造业存货采购管理机制进行研究,对其存货的特点、可追溯性系统进行了分析,并对轨道交通制造业可追溯性的实施与实现做出分析,希望能通过文中的分析,对我国轨道交通制造业可追溯性的发展做出绵薄贡献。     

BtoC模式下物流中心的动态选址模型

电子商务是随着计算机网络和通讯技术的迅速发展,特别是互联网的普遍应用而产生的一种全新的运作模式,在电子商务的BtoC模式下,由于顾客需求的不确定性和逆向物流的高频率性,客观上要求建立良好的物流网络。其中选址决定了整个物流网络的结构和规模,影响到物流系统中物流费用和客户服务水平的高低。针对现有的选址模型没有考虑时间变化对选址决策的影响和现实中用户需求的随机性,构建一个双向物流共享物流网络的动态选址模型,并把设施选址和库存决策结合在一起来讨究物流中心选址的最佳决策。     

突出优势特色创建交通工程品牌专业

交通工程是国民经济的基础产业,是社会发展的桥梁和纽带。石家庄铁道大学是一所专业特色鲜明的学校,交通是其主要学科。交通工程专业更是依托其特有的历史及资源优势,在多年办学的经历中,形成了"以轨道交通为特色,以铁路、公路以及城市交通为主体服务对象,融交通设施规划、设计、建设、运营管理为一体,工管并重、铁公并举"的人才培养体系,并从而形成自己的办学特色。     

The R&D location decision of the firm and “creative” regions—a survey

In the flurry of recent concern about and research on high technology firms and economic development, there is relatively little attention paid to the perspective of firms and their location decisions. This paper surveys the literature on the location of R&D facilities and on attempts to establish regions based on innovation and creativity. The locations of R&D facilities are constrained by the labor market for scientists and engineers. The locational needs of the firm revolve around ensuring both that professional labor will be able to be attracted to its R&D locations, and that communication (especially face-to-face communication) will be facilitated. Given these twin concerns, R&D is likely to locate primarily in large urban regions. The corresponding success of regions which hope to become major areas of spin-off and creativity is likewise constrained by the joint preferences of R&D workers, venture capital investors, and high-tech employers.     

Provisioning health care infrastructure in communities: Empirical evidences from West Bengal,India

We developed a framework to reinvigorate communities in terms of public health care infrastructure provisioning for outpatient needs within the neighborhoods. The health care seeking episode is often influenced by the physical and health care infrastructure availability within the neighborhood, need of the health care seeker as well as personal, household, occupational, and latent perception of the users. This empirical study has been developed for two different groups in West Bengal India, firstly based on location and secondly based on the choice of the health care seeker. In case of resident based approach, we focused on the revisit decision of the rural inhabitants who sometime tend to travel to the regional facilities in urban areas. Facility based approach analyzed the people who were at the regional facilities for health care services. We devised scenarios ascertaining improvisation in service delivery, emergency facility and mobility ease at local public facilities might reduce regional tours and instigate higher utilization of the neighborhood health care facility. We develop integrated choice and latent variable models to incorporate latent perception in choice of scenario for instigating revisit decision. Results showed choice of development scenarios have association with the household structure, social network, locational and infrastructural impedance. This framework lead to two distinct outcomes: (1) method to identify programs, those are essential to by initiate_revisit_to the health care facility (2) perception based assessment of the current mobility and health care infrastructure of the region, which could be instrumental in developing the overall health care infrastructural planning policy as a whole.     

On the exclusion theorem'

This paper examines the locational decision of the firm in a linear space economy under increasing returns to scale and imperfect competition. All intermediate locations are excluded by the firm from its possible location without being adversely affected. This is a stronger result than Sakashita's and Mathur's which require non-increasing returns to scale and perfectness in input markets. In this sense, our paper leads to a more general version of the Exclusion Theorem.     

基于遗传算法和模糊综合评价法物流配送中心选址研究

本文给出了关于配送中心选址的0-1混合整数线性规划模型,该模型要求在一些已知的备选点中选出一定数目的地点作为配送中心;并求出配送网络中的物流量,使配送网络总费用最小.由于这类模型属于NP难问题,为更好的求解此类问题,提出了定量化的遗传算法与定性化的模糊综合评价法相结合来确定配送中心地址的方法.     

Reconfiguring a set of coverage-providing facilities under travel time uncertainty

We study networks of facilities that must provide coverage under conditions of uncertainty with respect to travel times and customer demand. We model this uncertainty through a set of scenarios. Since opening new facilities and/or closing existing ones is often quite expensive, we focus on optimal re-configuration of the network, that is finding a facility set that achieves desired thresholds with respect to expected and minimal coverage, while retaining as many of the existing facilities as possible. We illustrate our model with an example of Toronto Fire Service. We demonstrate that relocating just a few facilities can have the same effect as opening a similar number of new ones. We develop exact and approximate solution approaches and test them with computational experiments. Algorithm based on Tabu Search (with certain novel components) appears to be particularly successful for this problem. We also analyze the multi-objective version of the problem, where the expected and minimum coverage levels are treated as objectives in addition to the objective of maximizing the number of pre-existing facilities in the final location set.     

大型超市选址影响因素的实证研究——以杭州市为例

本文主要探讨大型超市选址的影响因素及其对经营绩效的作用,基于杭州市区31个超市调查数据和模型分析,实证研究了人口因素、竞争因素、交通因素、商圈因素和自身条件对超市选址及经营绩效的影响,主要发现超市服务人口数、购买力的人口因素对超市选址决策和经营绩效影响最大;公交资源、超市规模、集客源数量、商圈繁荣度对超市经营绩效有显著正相关。     

Improving accessibility to rural health services: The maximal covering network improvement problem

Accessibility to health facilities is a critical factor in effective health treatment for people in rural areas of lesser-developed countries. In many areas accessibility is diminished by the lack of all-weather roads, making access subject to weather conditions. Location-allocation models have been used to prescribe optimal configurations of health facilities in order to maximize accessibility, but these models are based on the assumption that the underlying transport network is static and always available. Essentially, past work has ignored the potential impacts of improvements to the transport system in modeling access. In this paper we propose a model that treats the opposite side of the location/transport equation; that is, a model that treats existing facility locations as fixed and improves health service accessibility by upgrading links of the transport network to all-weather roads. This new model, called the Maximal Covering Network Improvement Problem (MC-NIP) is formulated as an integer-linear programming problem. An application of the MC-NIP model to the Suhum District of Ghana is presented, which shows that even a modest level of road improvement can lead to substantial increases in all-season access to health service.     

物流系统设施区位模型研究

本文系统介绍了以降低成本与提高服务效率为目标的传统物流系统设施区位模型即运输成本最小化模型与服务效率模型的发展与特点。作者认为确定性模型向不确定性模型演化是运输成本最小化模型发展的总趋势，服务效率模型包括以建设成本最小化为目标的完全覆盖模型和最大覆盖模型两类：在此基础上，介绍了近年来在供应链环境影响下发展而来的考虑库存成本与各级企业利益协调的库存-选址区位模型。     

Location choice for direct foreign investment in new hospitals in China by using ANP and TOPSIS

This study models location choices for foreign direct investments in new hospitals in China as an multi-criteria decision-making (MCDM) problem and designs develops a multidirectional relationship decision model combines the techniques of analytic network process (ANP) and technique for order performance based on similarity to the ideal solution (TOPSIS). This study discusses applying ANP to the relative weighting of multiple assessment criteria. The TOPSIS approach is employed to rank 15 counties without the Zhoushan of China’s Yangtze River Delta (YRD) region in terms of their overall performance under the decision model. To illustrate how the proposed approach is applied to the problem of selecting locations for new hospitals in China an empirical study of a real case is performed. This study demonstrates the effectiveness and feasibility of the proposed assessment procedure.     

基于层次分析法的战时后勤设施选址研究

分析战场环境下军事后勤设施选址决策的影响因素,构造选址评价指标体系的层次结构模型。基于层次分析法和群体决策理论,提出一种定性与定量相结合的战时后勤设施选址决策方法。并给出算例,演示具体的选址过程。研究表明运用层次分析法进行战时军事后勤设施选址,是合理、可行的,能够提高后勤设施选址决策的有效性和可靠性。     

Incorporating activity space and trip chaining into facility siting for accessibility maximization

Location models have been widely used to support locational decisions for various service provision. One common objective of location models has been to ensure maximal accessibility of sited facilities to demand populations. Accessibility evaluation in location models often assumes that trips originate from fixed locations (usually home) and are single purpose. These assumptions contradict the empirical evidence that suggests trips also commonly originate from non-home locations and may involve multiple stops. In this study, a new multi-objective location model is developed that extents the classic p-median problem (PMP) to account for a more realistic assessment of accessibility. Based on the individual accessibility assessment, notions of trip chaining and activity space are incorporated into the model development. In addition to fixed home locations, stops along chained trips are allowed for potential service site visits, and activity space is introduced as an additional dimension to evaluate accessibility of alternative opportunities. The effectiveness of the new model is demonstrated using an application in Tucson, AZ.     

Location in a congested city

This paper analyzes optimal location decisions in a city where both residential and employment locations are endogenously determined. A model is constructed which includes both traffic congestion among commuters and colocational externalities among firms. The model establishes that if location tax of the kind discussed by Koopmans and Beckman is imposed on both residential and employee locations, the private decisions of households and firms will produce an optimal pattern of location.     

Social enterprise factory location and allocation model: Small scale manufacturing for East Africa

The manufacturing location decision for social enterprises that work in the context of sustainable development is rarely based on a quantitative, analytical process. As a result, decisions may be far from profit-maximizing. Location and allocation optimization models have the potential to improve decisions and thus enable such enterprises to scale up their business as well as their impact. We develop and explain a single-period single-factory model, and also a two-echelon location and allocation model, to provide enterprises with information about optimal factory locations, and with future demand allocations and capacity-changing decision information. We apply the models to a company that manufactures and distributes solar cookers in East Africa. Our results illustrate that quantitative location and allocation models can significantly affect social enterprises by improving profitability. The case study shows strong cost-reduction potential of local manufacturing in developing countries due to high transportation costs for small production volumes. We discuss this model-recommended decision by weighing it against associated opportunities and risks. This paper aims to enable and encourage social and sustainability-oriented manufacturing enterprises to apply operations research methods in their strategic factory location decision-making.