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Publicações

Publicações por SYSTEM

2005

Cost efficiency, production and value-added models in the analysis of bank branch performance

Autores
Camanho, AS; Dyson, RG;

Publicação
JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY

Abstract
This paper develops a framework for performance appraisal in the context of a bank branch network. A data envelopment analysis model is advocated that can identify both input and output inefficiencies from a cost minimization perspective. The model is then applied to the analysis of a bank branch network and the production and value-added approaches are deployed jointly to give a comprehensive assessment of bank branch efficiency. The sources of underperformance are identified and their managerial implications are explored.

2005

Cost efficiency measurement with price uncertainty: a DEA application to bank branch assessments

Autores
Camanho, AS; Dyson, RG;

Publicação
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
This paper enhances cost efficiency measurement methods to account for different scenarios relating to input price information. These consist of situations where prices are known exactly at each decision making unit (DMU) and situations with incomplete price information. The main contribution of this paper consists of the development of a method for the estimation of upper and lower bounds for the cost efficiency (CE) measure in situations of price uncertainty, where only the maximal and minimal bounds of input prices can be estimated for each DMU. The bounds of the CE measure are obtained from assessments in the light of the most favourable price scenario (optimistic perspective) and the least favourable price scenario (pessimistic perspective). The assessments under price uncertainty are based on extensions to the Data Envelopment Analysis (DEA) model that incorporate weight restrictions of the form of input cone assurance regions. The applicability of the models developed is illustrated in the context of the analysis of bank branch performance. The results obtained in the case study showed that the DEA models can provide robust estimates of cost efficiency even in situations of price uncertainty.

2005

Generating dynamic higher-order Markov models in web usage mining

Autores
Borges, J; Levene, M;

Publicação
KNOWLEDGE DISCOVERY IN DATABASES: PKDD 2005

Abstract
Markov models have been widely used for modelling users' web navigation behaviour. In previous work we have presented a dynamic clustering-based Markov model that accurately represents second-order transition probabilities given by a collection of navigation sessions. Herein, we propose a generalisation of the method that takes into account higher-order conditional probabilities. The method makes use of the state cloning concept together with a clustering technique to separate the navigation paths that reveal differences in the conditional probabilities. We report on experiments conducted with three real world data sets. The results show that some pages require a long history to understand the users choice of link, while others require only a short history. We also show that the number of additional states induced by the method can be controlled through a probability threshold parameter.

2005

A multi-attribute ranking solutions confirmation procedure

Autores
Cardoso, DM; De Sousa, JF;

Publicação
ANNALS OF OPERATIONS RESEARCH

Abstract
Ranking problems arise from the knowledge of several binary relations defined on a set of alternatives, which we intend to rank. In a previous work, the authors introduced a tool to confirm the solutions of multi-attribute ranking problems as linear extensions of a weighted sum of preference relations. An extension of this technique allows the recognition of critical preference pairs of alternatives, which are often caused by inconsistencies. Herein, a confirmation procedure is introduced and applied to confirm the results obtained by a multi-attribute decision methodology on a tender for the supply of buses to the Porto Public Transport Operator.

2005

Preface

Autores
Feliz Teixeira, JM; Carvalho Brito, AES;

Publicação
2005 European Simulation and Modelling Conference, ESM 2005 - Proceedings

Abstract

2005

Comparing a standard and a naive stock refill policies by means of simulation

Autores
Feliz Teixeira, JM; Brito, AESC;

Publicação
Modelling and Simulation 2005

Abstract
In this paper will be compared, by means of a next event dynamic simulation, two different stock refill policies applied to the same in-lined one-product Supply Chain. The first method is the Japanese method usually known as KANBAN(1) (similar to the "Two Bins" method, in terms of dynamics), and the second is a naive method named by the authors the "BanKan" for the reasons that will be explained later in this text. The surprising results obtained show an obvious operational advantage of the naive method, at least under the conditions of the present Supply Chain design and configuration. This method does not make use of any criteria dependent on the actual stock level at the facility, and it was also observed that the materials flow through the Supply Chain as in a "river without dams", and with extremely low local inventory, as it was defended by Taiichi Ohno, the father of just-in-time (JIT) systems, in the 1980s.

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