A MODEL FOR SWITCHING DISPATCHING RULES IN REAL TIME IN A FLEXIBLE MANUFACTURING CELL

We model choice of dispatching rules in real time (system state dependent) as a pattern recognition problem, using a modified version of Data Envelopment Analysis. A data base of system state and performance values is created from extensive simulation, and this data base is used to train the pattern-recognition model. Our results show that the model is very effective in choosing a mix of dispatching rules over a period of time, varying the mix with system objectives, and performing better than the strategy of using fixed rules. We show how “If-Then” decision rules can be created from the model and portrayed in a decision-tree-like diagram. Since such decision rules are based on rigorous mathematical foundations, optimization will be ensured in our approach.     

Vendor managed inventory in tramp shipping

This paper introduces a new problem to the OR community that combines traditional tramp shipping with a vendor managed inventory (VMI) service. Such a service may replace the more traditional contract of affreightment (COA) which for decades has been the standard agreement between a tramp shipping company and a charterer. We present a mathematical formulation describing the routing and scheduling problem faced by a tramp shipping company that offers a VMI service to its customers. The problem is formulated as an arc-flow model, and is then reformulated as a path-flow model which is solved using a hybrid approach that combines branch-and-price with a priori path-generation. To solve larger, and more realistic, instances we present a heuristic path-generation algorithm. Computational experiments show that the heuristic approach is much faster than the exact method, with insignificant reductions in solution quality. Further, we investigate the economic impact of introducing a VMI service, by comparing the results obtained with the new model with results obtained by solving the traditional routing and scheduling problem faced by tramp shipping companies using COA. The computational results show that it is possible to substantially increase supply chain profit and efficiency by replacing the traditional COAs with VMI services.     

A KNOWLEDGE-BASED DSS FOR MANAGERIAL PROBLEM DIAGNOSIS

A knowledge-based system supporting managerial problem diagnosis is described. The system provides the capability to monitor values of selected variables for problem situations. When problems are located, a list of problem symptoms is delivered to a problem processor for structuring and diagnosis. Problem structuring is based on a combination of concepts from expert systems and structural modeling. User assertions about cause-effect relationships between pairs of variables are maintained in a semantic network. Problem diagnosis uses the relationships in the semantic network to construct causation trees, the branches of which represent potential explanations of the problem symptoms. Mathematical models are constructed based on causation-tree branches, and values from the data base are used to test whether the model confirms the diagnosis. If so, the source of the problem has been located and it is then up to the user to resolve the problem. If the model fails to explain the problem, the model apparently is deficient and the user may perform “what if…” type scenarios in attempts to improve the model and search for problem causes. Realistic applications in the accounting and health care areas are discussed.     

Release of maintenance jobs in a decentralized multi-stage production/maintenance system with continuous condition monitoring

Condition-based maintenance is analyzed for multi-stage production with a separate maintenance department. It is assumed that the conditions of the machines deteriorate as a function of multiple production parameters and that the task of maintenance is to keep up predefined operational availabilities of the individual machines. In this context the problem of determining the optimal machine condition that triggers the release of a preventive maintenance job and the problem of scheduling maintenance jobs at the maintenance department arise. Existing approaches to solve these problems either assume a monolithic production/maintenance system or concentrate on a decentralized system in which the information flow and resource transfer do not cause delays. With our paper we aim at (1) deriving a triggering mechanism that is able to cope with relaxed assumptions and at (2) developing specific priority rules for scheduling maintenance jobs. Therefore, in this paper a specific continuous condition monitoring and a suitable information exchange protocol are developed, factors determining the release situation are operationalized, impacts of choosing the triggering conditions are identified and the components of specific priority rules for scheduling maintenance jobs are clearly elaborated. Finally the performance of the resulting solution approach is analyzed by simulations. Thereby, relevant characteristics of the production/maintenance system, the maintenance task and relevant priority rules are varied systematically. This research contributes answers to the questions on how the exchange of local information can be structured, the parameters of condition-based maintenance can be set and on what maintenance-specific priority rules can be applied in case of incomplete information about deterioration in a decentralized multistage production/maintenance system.     

基于可变精度粗糙集的新兴技术企业信用风险识别

针对新兴技术企业信用风险评估的必要性和现有评估方法仅局限于财务指标且指标之间高度相关的缺点,借鉴了可变精度粗糙集（VPRS）模型具有噪声数据的强适应能力和强抗干扰能力的优点,提出了一类基于VPRS的新兴技术企业信用风险识别方法,并用已上市的部分新兴技术企业对其进行实证检验,检验结果表明了该方法具有较好的识别能力。该方法首先运用VPRS理论的最新研究成果,并借助于粗糙集分析软件ROSETYA,对由训练样本组成的数据关系表进行数据补缺、离散化及属性的β约简等处理,从而导出识别规则,形成识别规则库;然后集成二叉树构建一类新兴技术企业信用风险识别方法;最后用测试样本对方法的识别精度进行检验。     

基于用户规模的双边平台适应性动态定价策略研究

鉴于交叉网络效应导致用户加入双边平台的效用随用户规模动态变化,提出根据用户规模进行适应性动态定价的策略思想,并运用数值计算方法对该定价策略的效果进行深入研究。首先,引入平台动态竞争建模方法,构建了包含用户规模的双边平台适应性动态定价模型;接着,根据数值计算结果对动态定价与静态定价的效果进行比较;最后,考察了平台竞争主要参数的变化对动态定价策略效果的影响。研究表明：（1）动态定价显著优于静态定价,模型主要参数的取值变动不会改变动态定价具有相对优势这个定性结论;（2）提升服务质量或改变基准用户数不会明显增加动态定价的相对优势,但强交叉网络效应或前瞻性用户都会增强动态定价的相对优势。研究结果有助于平台企业管理者更好地制定平台定价策略。     

Operations research from the viewpoint of general systems theory

This paper examines the operations research process from the viewpoint of General Systems Theory. The components of the OR process and the relations between them are critically examined. The five components are: (1) the “reality” of the problem situation, (2) the conceptual model of the problem situation, (3) the scientific model of the conceptual model, (4) the solution to the scientific model, and (5) the implementation of the solution. The paper argues that we have sub-optimized both our knowledge (study) and our application of the OR process. That is, there have been extremely few studies and applications of OR which have concerned themselves with OR from a whole systems point of view. The paper argues that without a whole systems perspective OR can neither be understood nor effectively applied.     

An integrated approach for manpower planning in the service sector

The manpower planning problem receives considerable attention by the management of service organizations because they are typically labor intensive. Not only must optimal staff sizes be determined over an extended horizon, but optimal staff schedules which assign labor to tours of duty and specific tasks, given the available staff size, must also be found. Adding to the complexity arising from the interrelatedness of the staff-sizing and staff-scheduling problems is the existence of the conflicting multiple objectives of minimizing costs and maximizing customer service. The few methodologies reported in the literature which treat the complete manpower planning problem as stated above have several shortcomings. Some techniques place a severe strain on computational capabilities. Also, these methods confound the specification of the goal levels with the analysis of the relative goal weightings. Often the specification of the desired goal levels is made at a different level in the organizational hierarchy than the specification of the relative importance of the various goals. This paper suggests an approach which overcomes these shortcomings. The methodology utilizes a simulation model with an imbedded heuristic procedure for the staff-scheduling problem to identify realistic aggregate staff-size goals to be used in a multiple-objective staff-sizing model. The methodology is applied to the manpower planning problem of a large sectional center post office and the managerial benefits are discussed.     

大宗物资集中采购的调运计划研究

大宗物资调运问题是一个受多因素影响的复杂问题,一般来讲,其调运数量大、地域跨度大、时间紧。如何协调供需以及运输能力,保证物资采购部门的经济利益是本文所要研究的问题。本文首先给出了大宗物资集中采购的调运模式,然后针对采购部门在大宗物资调运过程中遇到的困难,为采购部门提出了以获取数量折扣、准时采购、降低库存成本和协调运输能力为准则的调运计划模型。数值计算表明应用本文所建模型编制调运计划能够达到降低采购费用、协调运输能力的目的,为大宗物资调运计划的编制提供了一种较为有效的方法。     

Capital budgeting and lagrangian relaxation: A case study

This paper presents a new approach to the classical multiyear capital budgeting problem. Three basic operational principles, arising out of an actual implementation of such a model, are specifically addressed in this approach. These principles are: (1) all budgets except that of the first year possess a degree of flexibility; (2) the user favours a series of near optimal solutions to a single optimal solution; and (3) an effective low cost procedure for dealing with large problems is required. Using the particular example of capital budgeting in the area of highway maintenance, an algorithm is developed and computational results for a variety of problem sizes are presented.     

我国工业电力用户价值画像模型构建与应用研究

在新型冠状病毒感染肺炎疫情对我国电力市场造成巨大冲击的宏观背景下,为进一步提升我国供电企业营销服务资源配置效能,最大化撬动供电企业的综合效益,笔者开展了我国工业电力用户价值画像模型研究。本文对电力用户价值进行了分析和定义,从安全稳定价值(S)、经济效益价值(E)、契约信用价值(C)与有序用电价值(O)四个维度,构建了我国工业电力用户价值评级SECO指标模型,并集成智能算法中的RST(粗糙集理论)与数据挖掘技术中的PAM(围绕中心点切割聚类算法),构造了一种半监督自动化用户价值识别、预测与特征展示模型,模型包括基于RST的指标体系设计、基于Gower相异度系数与PAM的用户价值评级,以及基于用户画像的价值特征展示三大模块。其中,为增强聚类分析结果的科学性与可靠性,采用霍普金斯统计量进行聚类趋势判断,利用间隔统计量输出理论最佳聚类数目,运用轮廓系数评估模型效果与识别误判样本。以我国南方电网公司下属某供电企业电力用户数据进行模型测试与应用研究,得到具有较高解释性与区分度的用户细分方案,表明本模型是一套可行有效的用户价值评级与特征可视化工具。     

The planning of a department store

A town or village attracts people from its hinterland to purchase goods by virtue of the amount and variety of goods on offer. Similarly, a department store attracts customers away from cempetitors by means of displays, staff expertise, stock holdings and numerous other parameters. The store is generally free to manipulate these parameters subject to certain restrictions; the manipulation will have a direct affect on the ultimate profitability of the store. This paper describes some current research that is being carried out in conjunction with a department store group. The ultimate aim is to link the corporate planning of the group and each store to detailed socioeconomic data describing the population. Some aspects of the problem have been investigated in depth, some are currently being discussed and some have not been considered at all as yet. The latest position will be reported and hopefully some feedback will be engendered.     

Interactive Multiple Objective Decision Support for Sales Force Sizing and Deployment*

An interactive decision aid is introduced for the deployment of two sales resources: salespeople and sales support staff. The aid consists of a normative sales resource allocation model with five objectives and an interactive multiple objective programming solution procedure. The specific decision problem addressed involves the assignment of salespeople and sales support people to customer accounts and the allocation of the time they spend on these accounts. The authors contribute to the existing sales resource modeling literature by dealing with the deployment of two sales resources and interactively solving this problem with respect to five short-run and long-run objectives of the firm. This approach differs from existing sales force modeling efforts in which the solution is found noninteractively by optimizing a single sales resource model with respect to a single objective, often short-run sales. An application of the decision aid to the deployment problem of an industrial sales force manager is presented. Furthermore, useful extensions of the basic sales resource allocation model are discussed.     

The planning of cycle trips in the province of East Flanders

Traditional route planners assist in finding the shortest or fastest route from one place to another. This paper presents a novel approach to path finding in a directed graph, namely a target distance, motivated by the problem that a recreational cyclist deals with when searching a nice route of a certain length. The problem is defined as a variant of the arc orienteering problem (AOP), a new combinatorial optimisation problem in which the score of a route in a directed graph has to be maximised by visiting arcs, while each arc can be visited at most once and the total cost of the route should not exceed a predefined cost. The contribution of this paper is threefold: (1) a mathematical model of the AOP is provided, (2) a metaheuristic method that solves AOP instances to near optimality in 1 s of execution time, is proposed and evaluated, and (3) two real-life applications of the method are presented. An on-line cycle route planning application offers personalised cycle routes based on user preferences, and an SMS service provides cyclists “in the field” with routes on demand.     

Point‐of‐Dispensing Location and Capacity Optimization via a Decision Support System

Dispensing of mass prophylaxis can be critical to public health during emergency situations and involves complex decisions that must be made in a short period of time. This study presents a model and solution approach for optimizing point‐of‐dispensing (POD) location and capacity decisions. This approach is part of a decision support system designed to help officials prepare for and respond to public health emergencies. The model selects PODs from a candidate set and suggests how to staff each POD so that average travel and waiting times are minimized. A genetic algorithm (GA) quickly solves the problem based on travel and queuing approximations (QAs) and it has the ability to relax soft constraints when the dispensing goals cannot be met. We show that the proposed approach returns solutions comparable with other systems and it is able to evaluate alternative courses of action when the resources are not sufficient to meet the performance targets.     

基于意外度的关联规则深层知识发现及应用研究

为了弥补传统关联规则挖掘产生大量冗余规则、难以直接用于决策支持的不足,本文提出了一种基于用户已有知识的规则意外度评价方法,并在此基础上设计了基于意外度的深层关联规则挖掘算法。算法的优点在于能够将用户已知的规则作为领域知识加入到数据挖掘过程从而有效过滤和已知规则相近的冗余规则,并且可以将新得到的规则加入知识库中实现知识的积累和重用。最后本文采用一个商场数据验证了该算法的有效性,并且对具有回馈模式的关联规则在商品促销中的作用进行了分析。     

Personal computing and support services

This paper reports the results obtained from a field study of 173 US companies which have implemented personal computing in the past five years. The study establishes the relationship between (i) the support services provided by the MIS department and its control over the PC acquisition process and (ii) and degree of information system (IS) management concerns with personal computing problems such as user training and user experience and the existence of selected organizational programs and policies for personal computing. This study provides empirical evidence concerning the above relationships by formulating and testing three propositions.     

The status of the systems approach

This paper is an assessment of the attempts by Ackoff, Beer and Churchman to provide a justification for the claim that OR is a science. These writers tackle the problem using the philosophies of positivism, pragmatism and conventionalism/idealism in an attempt to build an ideal scientific methodology for OR. The conclusions reached are that no such methodology can exist and that philosophy confuses rather than clarifies the nature of OR as a science. The weakness of the philosophical approach to some of the problems faced by OR is demonstrated through a discussion of Ackoff and Emery's analysis ‘On Purposeful Systems’. An outline is given of an alternative framework through which the problems of practising OR can more fruitfully be viewed.     

Concepts,Theory, and Techniques DISTRIBUTED COMPUTER SYSTEM DESIGN: A MULTICRITERIA DECISION-MAKING METHODOLOGY*

The design of distributed computer systems (DCSs) requires compromise among several conflicting objectives. For instance, high system availability conflicts with low cost which in turn conflicts with quick response time. This paper presents an approach, based on multi-criteria decision-making techniques, to arrive at a good design in this multiobjective environment. An interactive procedure is developed to support the decision making of system designers. Starting from an initial solution, the procedure presents a sequence of non-dominated vectors to designers, allowing them to explore systematically alternative possibilities on the path to a final design. The model user has control over trade-offs among different design objectives. This paper focuses on the details of the mathematical model used to provide decision support. Accordingly, a formulation of DCS design as a multicriteria decision problem is developed. The exchange search heuristic used to generate nondominated solutions also is presented. We argue that multicriteria models provide a more realistic formulation of the DCS design problem than the single-criterion models used widely in the literature. While obtaining a clear definition of design objectives (single or multiple) is an important activity, by explicitly acknowledging the trade-offs among multiple objectives in the design process, our methodology is more likely to produce a better overall design than methods addressing a single criterion in isolation.     

Effects of the implementation of information technology on employees' strain and job satisfaction: a context-dependent approach

The effects on staff of the implementation of new office information technology were investigated in ten companies in Vienna using a longitudinal design. Strain and satisfaction of 331 employees (implementation sample: n = 212; control sample: n = 119) were measured at five points in time over a period of 22 months. The study is based on a context-dependent approach. Personal factors (individual differences, external load) were assessed by questionnaires, and situational factors (job design, implementation content and implementation context) by objective measures. The impact of these factors on employees' strain responses was tested using structural equation modelling (SEM). While the implementation of new technology as such made no significant contribution to the explanation of strain variables, a reasonable model fit was achieved when implementation characteristics were taken into account. The data suggest that negative effects of implementations must be expected if (1) adaptational demands do not include the enhancement of employee qualifications, (2) character-based user interfaces are not replaced, and (3) employees have few or no opportunities to participate in the implementation process.