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Publications

2012

A new clustering algorithm for load profiling based on billing data

Authors
Fidalgo, JN; Matos, MA; Ribeiro, L;

Publication
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
In open energy markets, the settlement process between distribution operators and traders is made on an hourly (or 15 min) basis, while LV consumers' billing data continues to result from monthly energy bills. In order to reconcile these two different realities, load profiling is used as a means to redistribute the consumed energy of each trader's portfolio by hourly intervals, according to recorded consumption patterns. This paper presents a new clustering approach to derive typical load diagrams that can be used in the process. The algorithm uses real load diagrams obtained in measurement campaigns to define classes (in the billing information space) that maximize the compactness of the diagrams in each class. The methodology was developed in a project with EDP Distribution (the Portuguese distribution system operator) and the result was approved by the Regulatory Authority that adopted the proposed profiles for market use.

2012

Impact of environmental factors on the classification of power quality disturbances in grid-connected wind energy systems

Authors
Mohanty, SR; Kishor, N; Ray, PK; Catalao, JPS;

Publication
Proceedings of the IASTED International Conference on Power and Energy Systems, EuroPES 2012

Abstract
This paper presents the effect of environmental factors, such as wind speed change, on the classification of power quality (PQ) disturbances in grid-connected wind energy systems. Initially, based on the selection of suitable features and 3-Dimensional feature plots, the PQ disturbances are classified. Further, the disturbances are accurately classified using S-transform based feature extraction followed by classification by modular probabilistic neural network (MPNN), support vector machines (SVMs) and least square support vector machines (LS-SVMs). Different types of sag and swell disturbances due to the change in load and wind speed are created using MATLAB/Simulink and an experimental prototype setup for the classification problem. The results reveal that S-transform based extracted feature data, when trained with MPNN, SVMs and LS-SVM, can effectively classify the PQ disturbances. The accuracy and reliability of the proposed classifier are also validated on signals with noise content. A comparative study is also carried out to determine the robustness of the techniques used. Finally, conclusions are duly drawn.

2012

Growth trends in boys and girls (10-17 years-old) from autonomous region of Madeira, Portugal between 1996-1998 and 2007-2009

Authors
Sousa, B; Oliveira, BMPM; de Almeida, MDV;

Publication
ANNALS OF HUMAN BIOLOGY

Abstract
Background: Growth trends have never been studied in adolescents of the Autonomous Region of Madeira, Portugal. Aims: To analyse growth trends in weight, height, body mass index (BMI), waist circumference (WC), mid-upper arm circumference (MUAC) and triceps skin-fold thickness (TST) of adolescents (10-17 years old) of the Autonomous Region of Madeira between 1996-1998 and 2007-2009. Subjects and methods: A cross-sectional study was carried out between 2007-2009, including 4314 adolescents, 2237 girls and 2077 boys (10-17 years old). To study secular growth trends, data were compared with a sample from 1996-1998, comparing the means for each anthropometric variable by age and sex using the independent-sample t-test. Results: An average increase was found in weight of 5.8 kg in boys and 6.3 kg in girls; in height of 3.0 cm in boys and 3.7 cm in girls; in BMI of 1.5 kg/m(2) in boys and 1.7 kg/m(2) in girls; in WC a difference of 5.6 cm and 4.9 cm for boys and girls, respectively, and for MUAC a difference of 2.7 cm in boys and 2.0 cm in girls. No differences were found in TST in boys, but in girls an increase of 1.2mm was observed. Conclusions: A general increase in anthropometric measurements, more marked in weight, BMI, WC and MUAC and at younger ages, was observed.

2012

Java JCA/JCE programming in Android with SD smart cards

Authors
Maia, LA; Correia, ME;

Publication
SISTEMAS Y TECNOLOGIAS DE INFORMACION, VOLS 1 AND 2

Abstract
The mobile phone is currently the preferred means by which people can communicate and interact with each other at a distance. Not only that, the smart-phone nowadays constitutes the full embodiment of the truly personal device users carry constantly with them, everywhere. They are therefore the ideal means by which the user can casually and conveniently interact with Information systems. It can also act as a convenient and highly practical storage place for sensitive identity information. Moreover nowadays there is a real urgent need to have in place secure, non-refutable and securely managed identities and communications, with sufficiently strong authentication mechanisms that can assure, among other important properties, strong non-repudiation. In this paper we describe how we have managed to combine the functionalities provided by OpenSC and the University of Graz IAIK java security provider to more easily port java security applications based on the desktop JCA API to the Android platform. This enables us to take advantage of the full extent of the security programming facilities provided by the Java programming language on android devices equipped with smart digital (SD) based smart cards.

2012

Finding interesting contexts for explaining deviations in bus trip duration using distribution rules

Authors
Jorge, AM; Mendes Moreira, J; De Sousa, JF; Soares, C; Azevedo, PJ;

Publication
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Abstract
In this paper we study the deviation of bus trip duration and its causes. Deviations are obtained by comparing scheduled times against actual trip duration and are either delays or early arrivals. We use distribution rules, a kind of association rules that may have continuous distributions on the consequent. Distribution rules allow the systematic identification of particular conditions, which we call contexts, under which the distribution of trip time deviations differs significantly from the overall deviation distribution. After identifying specific causes of delay the bus company operational managers can make adjustments to the timetables increasing punctuality without disrupting the service. © Springer-Verlag Berlin Heidelberg 2012.

2012

A NOVEL FRAMEWORK FOR MODELING VALUE FOR THE CUSTOMER, AN ESSAY ON NEGOTIATION

Authors
Nicola, S; Ferreira, EP; Pinto Ferreira, JJP;

Publication
INTERNATIONAL JOURNAL OF INFORMATION TECHNOLOGY & DECISION MAKING

Abstract
This paper proposes a novel framework for modeling the Value for the Customer, the so-called Conceptual Model for Decomposing Value for the Customer (CMDVC). This conceptual model is first validated through an exploratory case study where the authors validate both the proposed constructs of the model and their relations. In a second step the authors propose a mathematical formulation for the CMDVC as well as a computational method. This has enabled the final quantitative discussion of how the CMDVC can be applied and used in the enterprise environment, and the final validation by the people in the enterprise. Along this research, we were able to con firm that the results of this novel quantitative approach to model the Value for the Customer is consistent with the company's empirical experience. The paper further discusses the merits and limitations of this approach, proposing that the model is likely to bring value to support not only the contract preparation at an Ex-Ante Negotiation Phase, as demonstrated, but also along the actual negotiation process, as finally confirmed by an enterprise testimonial.

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