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Publicações

2018

An electronic marketplace for airlines

Autores
Reis, L; Rocha, AP; Castro, AJM;

Publicação
Communications in Computer and Information Science

Abstract
In this paper we propose an airline marketplace, modeled as a multi-agent system with an automated negotiation mechanism, where airlines can announce availability of resources (aircraft or aircraft and crew) for lease and other airlines can go there to contract resources to fill gaps in the operation, typically due to disruptions and/or an unexpected increase on the operation. The proposed negotiation occurs in several rounds, where qualitative comments made by the buyer agent on proposals sent by the sellers enables these to learn how to calculate new proposals, using a case-based reasoning methodology. © 2018, Springer International Publishing AG, part of Springer Nature.

2018

Automatic Generation of Disassembly Sequences and Exploded Views from SolidWorks Symbolic Geometric Relationships

Autores
Costa, CM; Veiga, G; Sousa, A; Rocha, L; Oliveira, E; Cardoso, HL; Thomas, U;

Publicação
2018 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS (ICARSC)

Abstract
Planning the optimal assembly and disassembly sequence plays a critical role when optimizing the production, maintenance and recycling of products. For tackling this problem, a recursive branch-and-bound algorithm was developed for finding the optimal disassembly plan. It takes into consideration the traveling distance of a robotic end effector along with a cost penalty when it needs to be changed. The precedences and part decoupling directions are automatically computed in the proposed geometric reasoning engine by analyzing the spatial relationships present in SolidWorks assemblies. For accelerating the optimization process, a best-first search algorithm was implemented for quickly finding an initial disassembly sequence solution that is used as an upper bound for pruning most of the non-optimal tree branches. For speeding up the search further, a caching technique was developed for reusing feasible disassembly operations computed on previous search steps, reducing the computational time by more than 18%. As a final stage, our SolidWorks add-in generates an exploded view animation for allowing intuitive analysis of the best solution found. For testing our approach, the disassembly of two starter motors and a single cylinder engine was performed for assessing the capabilities and time requirements of our algorithms. © 2018 IEEE.

2018

Wine productivity per farm size: A maximum entropy application

Autores
Galindro, A; Santos, M; Santos, C; Marta Costa, A; Matias, J; Cerveira, A;

Publicação
Wine Economics and Policy

Abstract
The size of a farm is one of the factors that influence its productivity, in an ambiguous relationship that is often discussed in the industrial economy. In Portugal, the Demarcated Douro Region (DDR) is characterized by very small farms. Usually, this trend is considered a limitating factor in the profitability of the wine farms. In order to assess the correctness of this sentence, the variation of wine productivity per land size, from 2010 to 2016, was studied in the DDR, considering its three distinctive areas: Baixo Corgo, Cima Corgo and Douro Superior. The farms were categorized in nine different size ranges; as these variables outnumber the available seven observations, the Generalized Maximum Entropy (GME) estimator was used, since it suits the need to solve an ill-conditioned problem. GME was applied with the MATLAB (MATrix LABoratory) software along with the Bootstrap technique. According to the simulations, larger farms (with an area greater than 20 ha) on Douro Superior and Cima Corgo reveal higher marginal productivity given the current state of the region. On the other hand, Baixo Corgo's results suggest that medium-sized farms (with area ranges between 2 and 5 ha) display higher marginal increments to the region wine productivity. © 2018 UniCeSV, University of Florence

2018

Development of a dynamic model for twin hull ASVs

Autores
Pinto, AF; Cruz, NA; Pinto, VH; Ferreira, BM;

Publicação
2018 OCEANS - MTS/IEEE KOBE TECHNO-OCEANS (OTO)

Abstract
This paper presents an overview of a generalized 6 degrees of freedom model for surface vessels and explains how it can be extended for twin hull surface vehicles. The extended model takes into account the hull characteristics (dimensions and location), which are important to improve the accuracy of simulations and the performance of controllers. The method involves the calculation of the submerged volume of each hull, location of each hull's center of buoyancy and restoring forces/ torques due to buoyancy contributions. To evaluate the proposed model, some simulations were performed, using an example of allocation of propulsion system and realistic hydrodynamic coefficients (added mass and damping) and inertial tensors.

2018

Smes’ internationalization in the American continent: A literature review [Internationalisation des pme sur le continent Américain: Revue de la littérature] [Internacionalização de pme no continente Americano: Revisão da literatura] [Internacionalización de pymes en el continente Americano: Revisión de la literatura]

Autores
Ribau, CP; Moreira, AC; Raposo, M;

Publicação
Innovar

Abstract
Considering the pressing interest of the academic community and the business world over the internationalization of Small and Medium-sized Enterprises (smes), this research is aimed to review the empirical literature about smes’ internationalization processes in the American continent, according to information included in the main academic databases. This study makes an in-depth analysis of 39 papers (out of a group of 329) published between 1999 and 2014, contributing to the construction of knowledge and the understanding of research in this field. This work allowed identifying patterns and trends, as well as concluding that smes’ internationalization research is USA-and-Canada-centered and is largely influenced by four main topics: internationalization theories, strategy, performance and international perspectives. According to the results, it is also concluded that research studies have mainly followed a quantitative approach. Conclusions and interpretations of opportunities for future research are important for both the academic community and the business world.

2018

Automated combination of bilateral energy contracts negotiation tactics

Autores
Pinto A.; Pinto T.; Silva F.; Praca I.; Vale Z.; Corchado J.;

Publicação
IEEE Power and Energy Society General Meeting

Abstract
This paper addresses the theme automated bilateral negotiation of energy contracts. In this work, the automatic combination between different negotiation tactics is proposed. This combination is done dynamically throughout the negotiation process, as result from the online assessment that is performed after each proposal and counter-proposal. The proposed method is integrated in a decision support system for bilateral negotiations, called Decision Support for Energy Contracts Negotiations (DECON), which in turn is integrated with the Multi-Agent Simulator of Competitive Electricity Markets (MASCEM). This integration enables testing and validating the proposed methodology in a realistic market negotiation environment. A case study is presented, demonstrating the advantages of the proposed approach.

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