Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

Publications by CEGI

2015

Self-organising socio-technical description in service systems for supporting smart user decisions in public transport

Authors
Dragoicea, M; Falcao e Cunha, JFE; Patrascu, M;

Publication
EXPERT SYSTEMS WITH APPLICATIONS

Abstract
This paper describes an exploration towards the transposition of service science principles into design guidelines. This aims at capturing value co-creation service interactions embedding customer experience in service design and delivery activities. The new Socio-Technical Systems Engineering (STSE) process is proposed to guide improved design, and it is exemplified with a new real time service that provides integrated information for trip planning in a city. The STSE process supports a high level visual modelling approach assisted by model execution and simulation tools. From a service engineering perspective, the outcomes of this process are artefacts that automatically support consistency among design steps and effective integration of customer experience and stakeholder requirements through iterative cycles related to service design. The application of the STSE process in the design of an exploratory case study of a real time information and travel planning service is validated through simulation using an executable representation of requirements. It can be executed over more complex transport service offerings, with different resource allocation algorithms, or different public transport planning services over a sample of real users requesting information. Results of such a simulation are beneficial for the users, for the service providers, and for the authorities managing public transport in city or metropolitan areas.

2015

A nonparametric methodology for evaluating convergence in a multi-input multi-output setting

Authors
Horta, IM; Camanho, AS;

Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
This paper presents a novel nonparametric methodology to evaluate convergence in an industry, considering a multi-input multi-output setting for the assessment of total factor productivity. In particular, we develop two new indexes to evaluate sigma-convergence and beta-convergence that can be computed using nonparametric techniques such as Data Envelopment Analysis. The methodology developed is particularly useful to enhance productivity assessments based on the Malmquist index. The methodology is applied to a real world context, consisting of a sample of Portuguese construction companies that operated in the sector between 2008 and 2010. The empirical results show that Portuguese companies tended to converge, both in the sense of a and beta, in all construction activity segments in the aftermath of the financial crisis.

2015

Measurement of input-specific productivity growth with an application to the construction industry in Spain and Portugal

Authors
Kapelko, M; Horta, IM; Camanho, AS; Lansink, AO;

Publication
INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS

Abstract
Decision making in companies requires an assessment of the efficiency and productivity of individual inputs to provide insights into the scope for improvement of inputs' use. This paper estimates an input-specific Luenberger productivity growth indicator that can be decomposed to identify the contributions of input-specific technological change, technical efficiency change and scale efficiency change. These components for a specific input sum up to the aggregated indicators which are then compared with the traditional Luenberger indicator. The application focuses on panel data of Spanish and Portuguese construction firms over the period 2002-2011, accounting for three inputs: materials, labor and capital. The results show that aggregated productivity change and its components computed from the input-specific productivity indicator are different from those obtained using a traditional approach. The results also indicate that productivity change is negative for labor and capital for construction firms in both Spain and Portugal, while productivity change of materials is positive for Portugal and negative for Spain. Productivity decline is worse for capital in the Spanish construction firms, and for labor in Portugal.

2015

Eco-efficiency assessment at firm level: An application to the mining sector

Authors
Oliveira, R; Camanho, A; Zanella, A;

Publication
Operations Research and Big Data: IO2015-XVII Congress of Portuguese Association of Operational Research (APDIO)

Abstract
Assessing firms' Eco-efficiency is important to ensure they succeed in creating wealth without compromising the needs of future generations. This work aims to extend the Eco-efficiency concept by including in the assessment new features related to environmental benefits. Eco-efficiency is evaluated using a DEA model specified with a Directional Distance Function. The new methodology proposed in this paper is illustrated with an application to world-class mining companies, whose results and managerial implications are discussed.

2015

Assessing Technical and Economic Efficiency of the Artisanal Dredge Fleet in the Portuguese West Coast

Authors
Oliveira, MM; Camanho, AS; Gaspar, MB;

Publication
OPERATIONAL RESEARCH

Abstract
The bivalve dredge fleet is by far the most extensively studied fleet among the Portuguese artisanal segment. It is considered one of the most important artisanal fisheries, essentially due to the number of fishermen and vessels involved and to the high volume and value of the catches. The present study aimed to explore the efficiency of the dredge fleets that operated in the west coast of Portugal between 2006 and 2012. The methodology was based on the use of data envelopment analysis to assess vessels' efficiency. The inputs considered included the number of days at sea, a biomass stock indicator, and the characteristics of the vessels (power, length and tonnage). The annual fishing quota per vessel was also included in the model as a contextual factor. In the technical efficiency analysis, the outputs were defined by the weight of captures for three different bivalve species. Using data on the prices of each species in the wholesale market, revenue efficiency was also estimated to complement the technical efficiency analysis. The results allowed to gain insights concerning the performance of both Northwest and Southwest fleets, considering both technical and economic aspects of the fishery. It was also possible to identify the benchmark vessels, whose practices should be followed by the other vessels of the fleet.

2015

The phycotoxins' impact on the revenue of the Portuguese artisanal dredge fleet

Authors
Oliveira, MM; Camanho, AS; Gaspar, MB;

Publication
MARINE POLICY

Abstract
The bivalve dredge fleet, considered as one of the most important artisanal fleets due to the high value of the catches, is by far the most extensively studied among the Portuguese artisanal segment. Acknowledging the growing presence of marine phycotoxins in the waters, the present study explores their impact on the revenue of the fleet that operates along the coast of mainland Portugal. The results obtained using stochastic frontier analysis models enlighten the harmful impact of algae blooms on the activity of the artisanal dredge fleets. In particular, it was observed that in the Algarve region, where the frequency and the intensity of these episodes is higher, the sustainability of the dredge fishing activity is seriously compromised by the phycotoxins.

  • 126
  • 193