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Publicações

2013

Using roles to model crosscutting concerns

Autores
Barbosa, FS; Aguiar, A;

Publicação
AOSD

Abstract
In object oriented languages the problem of crosscutting concerns, due to limitations in the composition mechanisms, is recurrent. In order to reduce this problem we propose to use roles as a way of composing classes that extends the Object Oriented approach and can be used to model crosscutting concerns. To support our approach we developed a role language that extends Java, while being compatible with existing virtual machines. As validation we conducted a case study using three open source systems. We identified crosscutting concerns in the systems and then modeled them using our role approach. Results show that roles are a viable option for modeling crosscutting concerns. Copyright © 2013 ACM.

2013

Assessing child well-being through a new multidimensional child-based weighting scheme index: An empirical estimation for Portugal

Autores
Fernandes, L; Mendes, A; Teixeira, A;

Publicação
JOURNAL OF SOCIO-ECONOMICS

Abstract
Assessing child well-being through composite summary indexes is one of the most recent developments regarding child well-being measurement. Using a new index that takes into account the children's own perspectives, this paper presents empirical evidence on the main determinants of overall child wellbeing. Econometric estimations, based on a sample of 1246 children enrolled in the 3rd-6th grades of schools located in the Northern region of Portugal, convey two main results: (1) the parents' educational background and professional status, in particular, an unemployed father, are the most important factors affecting child well-being and (2) children from households with double or foreign nationality are worse off than those with Portuguese nationality. These results support the positive role of policies targeting the qualifications and employment opportunities for parents, as well as the need for inclusive policies for immigrant households as a way to improve their children's well-being.

2013

ADAPTIVE SINUSOIDAL MODELING OF PERCUSSIVE MUSICAL INSTRUMENT SOUNDS

Autores
Caetano, M; Kafentzis, GP; Mouchtaris, A; Stylianou, Y;

Publicação
2013 PROCEEDINGS OF THE 21ST EUROPEAN SIGNAL PROCESSING CONFERENCE (EUSIPCO)

Abstract
Percussive musical instrument sounds figure among the most challenging to model using sinusoids particularly due to the characteristic attack that features a sharp onset and transients. Attack transients present a highly nonstationary inharmonic behaviour that is very difficult to model with traditional sinusoidal models which use slowly varying sinusoids, commonly introducing an artifact known as pre-echo. In this work we use an adaptive sinusoidal model dubbed eaQHM to model percussive sounds from musical instruments such as plucked strings or percussion and investigate how eaQHM handles the sharp onsets and the nonstationary inharmonic nature of the attack transients. We show that adaptation renders a virtually perceptually identical sinusoidal representation of percussive sounds from different musical instruments, improving the Signal to Reconstruction Error Ratio (SRER) obtained with a traditional sinusoidal model. The result of a listening test revealed that the percussive sounds modeled with eaQHM were considered perceptually closer to the original sounds than their traditional-sinusoidal-modeled counterparts. Most listeners reported that they used the attack as cue.

2013

Multi Objective Optimization of Coordinated Scheduling of Cranes and Vehicles at Container Terminals

Autores
Homayouni, SM; Tang, SH;

Publicação
MATHEMATICAL PROBLEMS IN ENGINEERING

Abstract
According to previous researches, automated guided vehicles and quay cranes in container terminals have a high potential synergy. In this paper, a mixed integer programming model is formulated to optimize the coordinated scheduling of cranes and vehicles in container terminals. Objectives of the model are to minimize total traveling time of the vehicles and delays in tasks of cranes. A genetic algorithm is developed to solve the problem in reasonable computational time. The most appropriate control parameters for the proposed genetic algorithm are investigated in a medium size numerical test case. It is shown that balanced crossover and mutation rates have the best performance in finding a near optimal solution for the problem. Then, ten small size test cases are solved to evaluate the performance of the proposed optimization methods. The results show the applicability of the genetic algorithm since it can find near optimal solutions, precisely and accurately.

2013

Scheduling Parallel Real-Time Tasks using a Fixed-Priority Work-Stealing Algorithm on Multiprocessors

Autores
Maia, C; Nogueira, L; Pinho, LM;

Publicação
2018 8TH IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL EMBEDDED SYSTEMS (SIES)

Abstract
This paper proposes a model for scheduling parallel real-time tasks. The proposed model uses a work-stealing approach to schedule real-time parallel task sets at runtime, where each job may present a nested fork-join structure, generate an arbitrary number of parallel jobs, and each parallel job inherits the timing properties of the job that spawns it.

2013

Multimethodology in Metaheuristics

Autores
Ferreira, JS;

Publicação
JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY

Abstract
As a combination of different methodologies or parts of methodologies, Multimethodology is becoming more frequent in OR practice. This paper contributes with a new proposal and a new field of application: the employment of Multimethodology in problem solving with Metaheuristics (Mh). A convenient selection of soft and hard methods will be considered, from Soft OR, Creativity and Metaheuristics, such as Strategic Choice Approach, SWOT Analysis and Divergent and Convergent thinking. Formulating the 'right' optimisation problem, choosing a method based on Mh and accomplishing an effective implementation is an imprecise decision-making process, which may require skills and ideas that are beyond the ordinary boundaries of Mh practice. The relevance and success of Mh have been well-known for decades, but some open questions concerning choice and implementation strategies, for instance, still remain. If these questions are not adequately answered, they may lose credibility in the long term. The quality of solutions and computational times are not the only criteria used to analyse Mh, nor are they the most important. Very often, the effectiveness of an approach has to be evaluated from the perspective of modelling and practical problem solving. This paper investigates the advantages of Multimethodology and, furthermore, it sketches a framework for a coherent and comprehensive comparison of Mh and recommends a dynamic guiding tool for their implementation.

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