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Publications

2015

Stochastic Modeling of Multienergy Carriers Dependencies in Smart Local Networks With Distributed Energy Resources

Authors
Neyestani, N; Yazdani Damavandi, M; Shafie Khah, M; Chicco, G; Catalao, JPS;

Publication
IEEE TRANSACTIONS ON SMART GRID

Abstract
In a multienergy system, there are different types of dependencies among the energy carriers. Internal dependencies refer to possible changes in the energy source in the presence of energy converters and storage, and are managed by the system operator through the control strategies applied to the equipment. External dependencies (EDs) are due to the choice of the energy supply according to customer preferences when alternative solutions are available. This paper introduces a new model of EDs within a multigeneration representation based on energy hubs. EDs are addressed through a stochastic model in order to take into account the possible uncertainty in the customers' decisions. This model is then used to introduce carrier-based demand response (DR) in which the user participates in DR programs aimed at promoting the shifting among different energy sources by preserving the service provided to the end users. The results obtained from the new model in deterministic and stochastic cases indicate the appropriateness and usefulness of the proposed approach.

2015

AN APPLICATION OF THE LEAN PRODUCTION TOOL STANDARD WORK

Authors
Braganca, S; Costa, E;

Publication
JURNAL TEKNOLOGI

Abstract
Standard Work is a very useful tool of the Lean Production paradigm to specify standards and to establish the best methods and sequences for each process and for each worker, helping to reduce wastes. Despite its usefulness, this tool is often underused, neglected and misunderstood. Apart from that, there is a lack of literature about Standard Work. It is possible to find many papers on Lean Production in general and on some Lean tools, but there are few that focus on or describe in detail this particular tool. The main purpose of this paper is to prove the validity and show the importance and the applicability of Standard Work. The main aspects and ideas to understand this tool are described, as well as the benefits of applying it in a real world manufacturing environment. In this paper, an application example is given on a production unit of an elevators company, following the Action-Research methodology. The main findings are that Standard Work is effectively a good tool to normalize work procedures, allowing increased flexibility and production, and decreased wastes and assembly errors.

2015

Speech Features for Discriminating Stress Using Branch and Bound Wrapper Search

Authors
Juliao, M; Silva, J; Aguiar, A; Moniz, H; Batista, F;

Publication
LANGUAGES, APPLICATIONS AND TECHNOLOGIES, SLATE 2015

Abstract
Stress detection from speech is a less explored field than Automatic Emotion Recognition and it is still not clear which features are better stress discriminants. The project VOCE aims at doing speech classification as stressed or not-stressed in real-time, using acoustic-prosodic features only. We therefore look for the best discriminating feature subsets from a set of 6125 features extracted with openSMILE toolkit plus 160 Teager Energy Operator (TEO) features. We use a Mutual Information (MI) filter and a branch and bound wrapper heuristic with an SVM classifier to perform feature selection. Since many feature sets are selected, we analyse them in terms of chosen features and classifier performance concerning also true positive and false positive rates. The results show that the best feature types for our application case are Audio Spectral, MFCC, PCM and TEO. We reached results as high as 70.4% for generalisation accuracy.

2015

A Pitch-Depth Bottom Following Controller for AUVs using Eigenstructure Assignment

Authors
Melo, J; Matos, A;

Publication
IFAC PAPERSONLINE

Abstract
This paper addresses the problem of bottom following by the MARES Autonomous Underwater Vehicle, and presents derivation of a controller able to cope with the peculiarities of such problem. In specific, the main requirement for the controller is the existence of no overshoot both in the depth and pitch outputs of the system. The existence of such time-domain requirements motivates the use of Eigenstructure Assignment techniques in the formulation of the controller. Simulation results obtained with a dynamic model of the MARES AUV are presented and discussed, indicating the validity of the proposed approach.

2015

Are Rankings of Financial Analysts Useful to Investors?

Authors
Aiguzhinov, A; Serra, AP; Soares, C;

Publication
SSRN Electronic Journal

Abstract

2015

Some notes and comments on the efficient use of information in repeated games with Poisson signals

Authors
Osório, A;

Publication
Operations Research Letters

Abstract
In the present paper we characterize the optimal use of Poisson signals to establish incentives in the "bad" and "good" news models of Abreu et al. (1991). In the former, for small time intervals the signals' quality is high and we observe a "selective" use of information; otherwise there is a "mass" use. In the latter, for small time intervals the signals' quality is low and we observe a "fine" use of information; otherwise there is a "non-selective" use.

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