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Publications

2015

Sizing and siting static synchronous compensator devices in the Portuguese transmission system for improving system security

Authors
Pereira Barbeiro, PNP; Moreira, C; Keko, H; Teixeira, H; Rosado, N; Moreira, J; Rodrigues, R;

Publication
IET GENERATION TRANSMISSION & DISTRIBUTION

Abstract
This study presents a methodology for siting and sizing static synchronous compensator (STATCOM) devices in the Portuguese transmission system in order to improve system security following severe grid faults. Security issues arise since the Portuguese transmission system incorporates significant levels of wind generation without fault ride through and reactive current injection capabilities during grid faults. As the transmission system operator (TSO) is responsible for assuring system security, the goal of the study is to take advantage of the proved STATCOM ability for injecting reactive current in order to mitigate the disconnection of large amounts of wind farms in case of severe grid faults. The proposed methodology was developed and tested in coordination with the Portuguese TSO and it is based on the formulation of an optimisation problem in order to minimise the installed STATCOM power while ensuring its compliance with the current grid code requirements, namely in what concerns to the system stability and security. Given the discrete and complex nature of the problem, a hybrid approach, combining both a heuristic method and an evolutionary particle swarm optimisation (EPSO) algorithm was developed. Results show the effectiveness of the proposed methodology as well as its robustness regarding the validity of the obtained solutions while facing the most severe operational scenarios.

2015

An integer programming approach for balancing and scheduling in extended manufacturing environment

Authors
Kays, HME; Karim, ANM; Varela, MLR; Santos, AS; Madureira, AM;

Publication
2015 10th Iberian Conference on Information Systems and Technologies, CISTI 2015

Abstract
In the fiercely competitive era induced by expansion of open business archetypes, the managerial aspects of Extended Manufacturing Environments (EMEs) are experiencing growing concerns. There is no scope of leaving a possible operational improvement unexplored. For enhanced operational efficiency and capacity utilization the balancing and scheduling problems of EMEs are, therefore, rightfully considered and an integer programme is proposed in this paper. The model is designed in a spread sheet and solved through What'sBest optimizer. The model capabilities is assessed through a test problem. The results have demonstrated that the model is capable of defining optimized production schedules for EMEs. © 2015 AISTI.

2015

Concurrent Learning of Visual Codebooks and Object Categories in Open-ended Domains

Authors
Oliveira, M; Lopes, LS; Lim, GH; Kasaei, SH; Sappa, AD; Tome, AM;

Publication
2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS)

Abstract
In open-ended domains, robots must continuously learn new object categories. When the training sets are created offline, it is not possible to ensure their representativeness with respect to the object categories and features the system will find when operating online. In the Bag of Words model, visual codebooks are usually constructed from training sets created offline. This might lead to non-discriminative visual words and, as a consequence, to poor recognition performance. This paper proposes a visual object recognition system which concurrently learns in an incremental and online fashion both the visual object category representations as well as the codebook words used to encode them. The codebook is defined using Gaussian Mixture Models which are updated using new object views. The approach contains similarities with the human visual object recognition system: evidence suggests that the development of recognition capabilities occurs on multiple levels and is sustained over large periods of time. Results show that the proposed system with concurrent learning of object categories and codebooks is capable of learning more categories, requiring less examples, and with similar accuracies, when compared to the classical Bag of Words approach using codebooks constructed offline.

2015

Operational Research

Authors
Almeida, JP; Oliveira, JF; Pinto, AA;

Publication
CIM Series in Mathematical Sciences

Abstract

2015

Operations Strategy Frameworks in Manufacturing, Services and Product-Service Systems

Authors
Barbosa, C; Azevedo, A;

Publication
2015 INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND SYSTEMS MANAGEMENT (IESM)

Abstract
Many definitions for operations strategy appear in literature. Yet, after analysing some of these important definitions, there were some common denominators: planning and decision-making. It is through correct operations strategy planning and decisions that organizations achieve competitive edge, and for this reason, the subject is of major importance. In this paper we present a review on operations strategy (OS) in manufacturing, services and product-service organizations. Through the literature analysis we found several differences and fewer similarities between OS in manufacturing and services and also the positioning of product-service systems (PSS) OS, comparing to OS in manufacturing and in services. Our foremost contribution is providing a literature review and an analysis on the content of the OS frameworks.

2015

Providing tools to enable information audit in social networks

Authors
Pinheiro, A; Cappell, C; Maciel, C;

Publication
Communications in Computer and Information Science

Abstract
In the moment that social networks arise as a new source of information, we also started to concern about the information shared in this environment. It is difficult to users of social networks to distinguish the accuracy of the information spreaded. The combination of auditability features and research directions in human-computer interaction area will guide the development of tools for evaluating information. We present prototypes of tools that once available, will allow users to decide about the credibility of information that they access and share. © Springer International Publishing Switzerland 2015.

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