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Publications

Publications by CESE

2011

Innovation, risk and proactivity: Are firms following these strategies?

Authors
Duarte, N;

Publication
WSEAS Transactions on Business and Economics

Abstract
In the present paper, management strategies are analysed in order to evaluate the degree of entrepreneurship in firms' management by the use of innovation, risk and proactivity strategies. Since we are dealing with management strategies, it is possible to relate them to the concept of Intrapreneurship. This study was done in a region of northern (Portugal Vale do Sousa) and focus on Industrial and Construction sectors. The region is composed of six concelhos1 in some of which it is possible to identify some industrial districts. In order to get a valid sample, a group of 251 firms were analysed. Each strategy was analysed individually and the results pointed to a lack of culture of entrepreneurship in firms' management. Only Proactivity presented a positive result in firms' management. When grouping the results, it was possible to conclude that the degree of intrapreneurship is very low and firms are surviving (even succeeding) by following conventional (old fashioned) management strategies.

2010

Partner selection in virtual enterprises

Authors
Crispim, JA; de Sousa, JP;

Publication
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH

Abstract
A virtual enterprise (VE) is a temporary organisation that pools member enterprises core competencies and exploits fast changing market opportunities. VEs offer new opportunities to companies operating with a growing number of participants (consumers, vendors, partners and others) in a global business environment. The success of such an organisation is strongly dependent on its composition, and the selection of partners therefore becomes a crucial issue. Partner selection can be viewed as a multi-criteria decision making problem that involves assessing trade-offs between conflicting tangible and intangible criteria, and stating preferences based on incomplete or non-available information. In general, this is a very complex problem due to the large number of alternatives and criteria of different types (quantitative, qualitative and stochastic). In this paper we propose an integrated approach to rank alternative VE configurations using an extension of TOPSIS (a technique for ordering preferences by similarity to an ideal solution) for fuzzy data, improved through the use of a tabu search meta-heuristic. A sensitivity analysis is also presented. Preliminary computational results clearly demonstrate the potential of the approach for practical application.

2010

A multiobjective metaheuristic for a mean-risk multistage capacity investment problem

Authors
Claro, J; de Sousa, JP;

Publication
JOURNAL OF HEURISTICS

Abstract
We propose a multiobjective local search metaheuristic for a mean-risk multistage capacity investment problem with irreversibility, lumpiness and economies of scale in capacity costs. Conditional value-at-risk is considered as a risk measure. Results of a computational study are presented and indicate that the approach is capable of producing high-quality approximations to the efficient sets with a modest computational effort. The best results are achieved with a new hybrid approach, combining Tabu Search and Variable Neighbourhood Search.

2010

A multiobjective metaheuristic for a mean-risk static stochastic knapsack problem

Authors
Claro, J; de Sousa, JP;

Publication
COMPUTATIONAL OPTIMIZATION AND APPLICATIONS

Abstract
In this paper we address two major challenges presented by stochastic discrete optimisation problems: the multiobjective nature of the problems, once risk aversion is incorporated, and the frequent difficulties in computing exactly, or even approximately, the objective function. The latter has often been handled with methods involving sample average approximation, where a random sample is generated so that population parameters may be estimated from sample statistics-usually the expected value is estimated from the sample average. We propose the use of multiobjective metaheuristics to deal with these difficulties, and apply a multiobjective local search metaheuristic to both exact and sample approximation versions of a mean-risk static stochastic knapsack problem. Variance and conditional value-at-risk are considered as risk measures. Results of a computational study are presented, that indicate the approach is capable of producing high-quality approximations to the efficient sets, with a modest computational effort.

2010

Flexible internal logistics based on AGV system's: A case study

Authors
Rocha, LF; Moreira, AP; Azevedo, A;

Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
Automated Guided Vehicles (AGV) are self-driven vehicles used to transport material between workstations in the shop floor without the help of an operator, although they can also be applied in security and exploration. They are widely used in material handling systems and flexible manufacturing systems, where production orders are constantly changing. Today, and due to the constant development of technology, sophisticated machinery is increasingly available, thus enabling manufacturing firms to achieve significant process and setup time reductions. With this development, enterprises are encouraged to leave mass production approaches and start adopting small productions lot sizes, leading to constant changes in the production operation's sequences as well as changes in the factory layout. As a consequence of the development of technology, products started to spend a big percentage of time in the queue line or being transported from one workstation/storage to another. With the introduction of AGVs production process flexibility may increase, which, in many productions processes, is still below the expectations due to the used transportation system (ex: conveyors). At the same time, with the AGVs it is possible, to decrease transportations times and costs. In this article, we will study by means of simulation, the impact of the use of an AGV transportation based system in an industrial coating application. The AGV will be responsible for transporting the parts from the system's entrance to the workstations. With this, flexibility in the production process will increase, which will be reflected in system's productivity. © 2010 IFAC.

2010

Virtual Factory Framework: An innovative approach to support the planning and optimization of the next generation factories

Authors
Azevedo, A; Francisco, RP; Bastos, J; Almeida, A;

Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
Industrial managers are in the expectation that the new generation factories bring more competitiveness to the manufacturing companies through innovative approaches, methods and tools that support the factory planning process. The concept of "factory as a product" perceives the factory as a complex long life product introducing design advantages for factory planning and optimization, seeking to improve quality, reduce ramp-up, product delivery and overall reduce time and costs. In order to attain these objectives, there is an urgent need for an innovative and suitable Virtual Factory Framework to structure the development of new generation factories. © 2010 IFAC.

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