Two-stage stochastic mixed-integer linear programming: The conditional scenario approach

In this paper we consider the two-stage stochastic mixed-integer linear programming problem with recourse, which we call the RP problem. A common way to approximate the RP problem, which is usually formulated in terms of scenarios, is to formulate the so-called Expected Value (EV) problem, which only considers the expectation of the random parameters of the RP problem. In this paper we introduce the Conditional Scenario (CS) problem which represents a midpoint between the RP and the EV problems regarding computational tractability and ability to deal with uncertainty. In the theoretical section we have analyzed some useful bounds related to the RP, EV and CS problems. In the numerical example here presented, the CS problem has outperformed both the EV problem in terms of solution quality, and the RP problem with the same number of scenarios as in the CS problem, in terms of solution time.     

Spatial directional robust Benefit of the Doubt approach in presence of undesirable output: An application to Italian waste sector

This paper introduces a new composite indicator method integrating the spatial dependence into the robust directional model in the case of undesirable outputs. The proposed approach is advantageous compared to the traditional and conditional robust Benefit-of-the-Doubt (BoD) models in that it allows to compare the performance of individual units with local cluster of peers. The methodology has been tested on a very detailed database of Italian municipalities for the year 2015 in the municipal solid waste collection and processing sector and confirms the existence of strong local constraints linked to the disposal facilities planned by higher level Authorities.     

An ACE in the hole: Twin family models for applied behavioral genetics research

Many studies investigate the genetic and environmental influences on traits using twin data and ACE models (A = additive genetic effects, C = shared environment effects, E = unshared environment effects). Unfortunately, relying on twins leads to biased results and limits what researchers can study. We introduce twin models and describe their problems. We show how to solve these problems with data from twins and their families, which allow modeling new effects such as the parent-to-child transmission of traits. We illustrate twin family models using extraversion (extroversion) data from the Virginia 30,000 twin family dataset, giving model specifications and code for the program Mplus. We conclude that if researchers are interested in understanding a broad sense of genetic influences on observed variables, traditional twin models are adequate. However, when data from twins and families are available, twin family models offer better and more interesting estimates of genetic and environmental effects.     

Estimating two-stage network Slacks-based inefficiency: An application to Bangladesh banking

This paper studies the performance of nineteen private commercial banks and two government-owned banks in Bangladesh during the period 2005–2008 using a slacks-based inefficiency measure and the directional technology distance function. Performance is measured assuming a black-box production structure and then the black-box is opened and examined using a two stage network production structure. Current period performance in maximizing desirable loans and securities investments and minimizing bad loans depends on how efficiently inputs at one stage of production are transformed into intermediate outputs which are used at a subsequent stage of production. In addition, current period production of the intermediate output is constrained by the amount of non-performing loans that were generated in an earlier period.     

关于农村劳动力流动的政策问题分析

本文主要从政策运行过程讨论农村劳动力流动的政策问题。已有的研究 (杜鹰、白南生等，１９９７；宋洪远、白南生等 ,２００１)表明 ,政策和体制是影响农村劳动力外出与回流的重要因素。我们在调查中也时常听到流动劳动力的抱怨 ,外出期间受到很多不公平的待遇和歧视。要全面深刻揭示农村劳动力外出与回流的现象及其原因 ,就必须对政策问题进行专门的讨论和分析。本文的分析主要是依据２００１年６月对东部发达地区山东威海、江苏常熟等市和同年７月对中部核心地区河南、湖南两省的三县两市 (郾城县、邓州市 ,临澧县、嘉禾县、浏阳市 )的实…     

Managing strategic change: An integrated approach

This paper sets out to identify and discuss an integrated approach to the management of strategic changes. Managing effectiveness, dealing with organizational cultures and managing organizational politics are discussed, focusing upon how to do so in order to encourage risk-taking, creativity and learning and to build self-esteem and performance. Such an approach allows the achievement of major changes in ways which lead to employees developing a fuller understanding of the nature of the business, its problems and its future.     

Hospital productivity measurement: An engineering approach

A model for measuring hospital productivity is proposed, based on the determination of standard inputs per case. From these standards and the number of cases passing through a hospital, total standard inputs can be determined. Division of the standard inputs by the actual inputs provides productivity figures for each kind of input. Standard inputs per class of cases are calculated, through a chain of matrices, from standard inputs per elementary operation. Classification of cases into diagnostic categories, and the validity of assuming a typical average set of treatments for each class, are discussed. A numerical example is presented which demonstrates the proposed approach for calculating manpower productivity in a maternity ward.     

An exact semidefinite programming approach for the max-mean dispersion problem

This paper proposes an exact algorithm for the Max-Mean dispersion problem (\(Max-Mean DP\)), an NP-Hard combinatorial optimization problem whose aim is to select the subset of a set such that the average distance between elements is maximized. The problem admits a natural non-convex quadratic fractional formulation from which a semidefinite programming (SDP) relaxation can be derived. This relaxation can be tightened by means of a cutting plane algorithm which iteratively adds the most violated triangular inequalities. The proposed approach embeds the SDP relaxation and the cutting plane algorithm into a branch and bound framework to solve \(Max-Mean DP\) instances to optimality. Computational experiments show that the proposed method is able to solve to optimality in reasonable time instances with up to 100 elements, outperforming other alternative approaches.     

An integrated approach for the electronic contract manufacturer selection problem

In the global competitive environment, lead companies have to outsource their manufacturing to electronic contract manufacturers (ECM) in order to reduce operational cost and capture higher profit. Thus, the process of selecting contract manufacturers to be strategic partners is important for these companies. For this reason, this paper proposes an integrated approach for the electronic contract manufacturer selection problem, combining the voting method and the goal programming (GP) model to take into account quantitative factors involved in the selection process, which is applied to a real-world ECM selection problem encountered by a leading provider of complete broadband access solutions. Results of the case study indicate that the voting method can acquire the rating information quickly from manufacturing managers based on suitable evaluating criteria. The rating information simultaneously incorporates ECMs' performance scores as a weight for each ECM. A production planner can easily employ the GP model and ECMs’ weight information to effectively assign demand quantities to ECMs. Therefore, the integrated approach is a practical and useful tool for solving the contract manufacturer selection problem.     

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.     

An approach to the impaired physician

The 1988 California Administrative Code requiring all acute care medical staffs to provide assistance to impaired physicians has not resulted in an increase in the annual census in the Medical Board of California Diversion Program. In part, this lack of an increase is due to the failure of some hospitals to form physician aid committees and to the poor functioning of such committees in other hospitals. The common reasons for these deficiencies are that the medical staff leadership does not think there are any impaired physicians on staff and that they don't know what the committee would do if it were formed. This attitude demonstrates a lack of appreciation for the prevalence of impaired physicians and the tremendous amount of work required (establishing policies and procedures) to identify and help them. This article discusses the prevalence of the impaired physician, the types of impaired physicians, a "cookbook" approach to managing these physicians, and the success of intervention.     

Implementation of JIT purchasing: An integrated approach

This article addresses the necessity of integration between buyer and supplier for effective implementation of the JIT system. An integrated lot-splitting model of facilitating multiple shipments in small lots is developed and compared with the existing approach in a simple JIT environment, single-buyer-single-supplier, under deterministic conditions for a single product. It is shown that the optimal policy adopted by the integrated approach can provide a strong and consistent cost-minimizing effect for both buyer and supplier over the existing approach.     

An analytic approach for planning computerized office systems

The increasing demand for timely business information as well as the need to improve the effectiveness of administrative operations are forcing managements to consider installing automated office systems. These systems provide text word processing capabilities, information management and communication options. Their planning and evaluation process considers decision issues that are, at times, in conflict with each other. This paper presents a decision framework for the planning and evaluation of computerized office systems. Attention is focused, in particular, on the selection and the integration of word processing systems in the broader context of future office developments. It evolved from several real acquisition cases where such systems had to be planned, evaluated and selected.     

Assessing opportunities for diversification—An analytical approach

This article demonstrates a system for the selection of industry sectors for diversification. It provides an analytical method for assessing both the attractiveness of an opportunity area as an investment and the extent to which it will match a company's current operations and their strengths and weaknesses, and describes how the system has been used in practice by a large consumer goods company.     

Development of engineering managers: An alternative approach

A persistent problem existing in many technical organizations is the effective development of engineering managers. The authors discuss the problem, typical approaches currently used in attempts to resolve it, and then offer an alternative approach. The suggested strategy entails standard, formal training methods coupled with provision of informal opportunities within the organization. While formal training provides the essential building blocks of managerial knowledge, it is suggested that informal opportunities allow the potential manager to put this knowledge to trial use in a variety of situations. The benefit for the engineer is a better understanding of the material learned and how it may be practically applied. The benefit for the organization is the realization and utilization of potentially untapped human resources.