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Publicações

2016

Spot sale of uncommitted LNG from Middle East: Japan or the UK?

Autores
Nikhalat Jahromi, H; Bell, MGH; Fontes, DBMM; Cochrane, RA; Angeloudis, P;

Publicação
ENERGY POLICY

Abstract
The importance of liquefied natural gas (LNG) is rising as demand for it grows rapidly and steadily due to growth in energy demand, the transition to a low carbon economy and the longer distances over which natural gas is now traded. Given its importance, this work proposes an optimization model that assists to decide on when and where LNG should be delivered by coordinating tanker type, assignment and routing, inventory management, contract obligations, arbitrage and uncommitted LNG. The model maximizes the profit mainly by taking advantage of price differences between different markets. The contributions of this work are twofold. First, following the analysis of expenses and revenues, a new mixed integer programming model for LNG liquefaction and shipping is proposed from a corporate finance perspective. Furthermore, a solution approach for it is implemented and tested. Second, the model is used to derive a short term trade policy for the Middle Eastern LNG producers regarding the spot sale of their uncommitted product to Japan or to the UK, namely to: dispatch to whichever market has the higher current spot price, regardless of the variability of the transport expenses.

2016

Bin packing and related problems: General arc-flow formulation with graph compression

Autores
Brandao, F; Pedroso, JP;

Publicação
COMPUTERS & OPERATIONS RESEARCH

Abstract
We present an exact method, based on an arc-flow formulation with side constraints, for solving bin packing and cutting stock problems-including multi-constraint variants-by simply representing all the patterns in a very compact graph. Our method includes a graph compression algorithm that usually reduces the size of the underlying graph substantially without weakening the model. Our formulation is equivalent to Gilmore and Gomory's, thus providing a very strong linear relaxation. However, instead of using column-generation in an iterative process, the method constructs a graph, where paths from the source to the target node represent every valid packing pattern. The same method, without any problem-specific parameterization, was used to solve a large variety of instances from several different cutting and packing problems. In this paper, we deal with vector packing, bin packing, cutting stock, cardinality constrained bin packing, cutting stock with cutting knife limitation, bin packing with conflicts, and other problems. We report computational results obtained with many benchmark test datasets, some of them showing a large advantage of this formulation with respect to the traditional ones.

2016

Analysis and Visualisation of Crowd-sourced Tourism Data

Autores
Leal, F; Dias, JM; Malheiro, B; Burguillo, JC;

Publicação
C3S2E

Abstract
The tourist behaviour has changed significantly over the last decades due to technological advancement (e.g., ubiquitous access to the Web) and Web 2.0 approaches (e.g., Crowdsourcing). Tourism Crowdsourcing includes experience sharing in the form of ratings and reviews (evaluation-based), pages (wiki-based), likes, posts, images or videos (social-network-based). The main contribution of this paper is a tourist-centred off-line and on-line analysis, using hotel ratings and reviews, to discover and present relevant trends and patterns to tourists and businesses. On the one hand, online, we provide a list of the top ten hotels, according to the user query, ordered by the overall rating, price and the ratio between the positive and negative Word Clouds reviews. On the other hand, off-line, we apply Multiple Linear Regression to identify the most relevant ratings that influence the hotel overall rating, and generate hotel clusters based on these ratings.

2016

ERP Selection using an AHP-based Decision Support System

Autores
Cruz Cunha, MM; Silva, JP; Goncalves, JJ; Fernandes, JA; Avila, PS;

Publicação
INFORMATION RESOURCES MANAGEMENT JOURNAL

Abstract
Selecting the best desirable Enterprise Resources Planning (ERP) system has been a critical problem for organizations for a long time, as the failure on the selection process may have a highly negative impact in terms of costs and market share of a company. It is one of the most important decision making issues covering both qualitative and quantitative factors for organization. Multiple-criteria decision-making has been proved to be a useful approach to analyze these conflicting qualitative and quantitative factors. Literature offers proposals and approaches to handle this kind of problem; Analytic Hierarchy Process (AHP) has been applied successfully in most cases of software packages selection problems. This paper proposes an AHP model for the selection of an ERP system. The model's set of criteria was extracted from the literature review and validated by Portuguese organizations. This model can be applied in the ERP system selection using a software application that is under development. This software application eases the application of the AHP process to the selection of ERP packages and will provide input from real-world cases that will allow updating and refining the model.

2016

ACADEMIC ENTREPRENEURSHIP IN LIFE SCIENCES: THE CASE OF A MODERATE INNOVATOR COUNTRY

Autores
Teixeira, AAC; Nogueira, J;

Publicação
JOURNAL OF DEVELOPMENTAL ENTREPRENEURSHIP

Abstract
The commercialization of research done by universities and research institutes is seen as a key element of entrepreneurship, justifying a better understanding of the entrepreneurial process within those institutions. Despite efforts in recent decades, there remains a widespread ignorance about who are the individuals with a greater vocation for research and marketing of knowledge. Focusing on a relatively unexplored context - the field of life sciences in a moderate innovator country, Portugal - this study adds new empirical evidence to the precedents of academic entrepreneurship. The results, based on 247 responses, evidence that entrepreneurship (including patent production, consultancy work and creation of start-up companies) is still very incipient. The econometric analysis of the "Index of entrepreneurial activity," shows that: (1) the phenomenon of academic entrepreneurship is within everyone's reach, but embraced by very few; and (2) academic entrepreneurship feeds on the exchange of knowledge and resources among universities and research institutes and their socio-economic environment. Thus, to increase academic entrepreneurship in life science in Portugal, the mechanisms to facilitate the interactions between universities and the business community must be strengthened, promoting the development of business clusters with the integration of the academic world, which will enable the transformation of knowledge into market products and services.

2016

Issues in number entry user interface styles: Recommendations for mitigation

Autores
Thimbleby, Harold; Oladimeji, Patrick; Masci, Paolo; Curzon, Paul;

Publicação
EAI Endorsed Trans. Creative Technologies

Abstract

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