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Publications

2015

An FPGA Framework for Genetic Algorithms: Solving the Minimum Energy Broadcast Problem

Authors
dos Santos, PV; Alves, JC; Ferreira, JC;

Publication
2015 EUROMICRO CONFERENCE ON DIGITAL SYSTEM DESIGN (DSD)

Abstract
Solving complex optimization problems with genetic algorithms (GAs) with custom computing architectures is a way to improve the execution time of this metaheuristic, which is known to consume considerable amounts of time to converge to final solutions. In this work, we present a scalable computing array architecture to accelerate the execution of cellular GAs (cGAs), a variant of genetic algorithms which can conveniently exploit the coarse- grain parallelism afforded by custom parallel processing. The proposed architecture targets Xilinx FPGAs and is used as an auxiliary processor of an embedded CPU (MicroBlaze). To handle different optimization problems, a high- level synthesis (HLS) design flow is proposed where the problem- dependent operations are specified in C++ and synthesised to custom hardware, thus requiring a minimum knowledge of digital design for FPGAs. The minimum energy broadcast (MEB) problem in wireless ad hoc networks is used as a case study. An existing software implementation of a GA to solve this problem is ported to the proposed computing array to demonstrate its effectiveness and the HLS- based design flow. Implementation results in a Virtex- 6 FPGA show significant speedups, while finding solutions with improved quality.

2015

Measures in Sectorization Problems

Authors
Rodrigues, AM; Ferreira, JS;

Publication
Studies in Big Data

Abstract
Sectorization means dividing a whole into parts (sectors), a procedure that occurs in many contexts and applications, usually to achieve some goal or to facilitate an activity. The objective may be a better organization or simplification of a large problem into smaller sub-problems. Examples of applications are political districting and sales territory division. When designing/comparing sectors some characteristics such as contiguity, equilibrium and compactness are usually considered. This paper presents and describes new generic measures and proposes a new measure, desirability, connected with the idea of preference. © 2015, Springer International Publishing Switzerland.

2015

IMC 2015: Proceedings of the International Management Conference

Authors
Au-Yong-Oliveira, Manuel; Moreira, António Carrizo; Ferreira, João José Pinto; Gonçalves, Ramiro;

Publication

Abstract
Articles successfully submitted to and presented at IMC 2015: The International Management Conference

2015

Generalized Extraction of Real-Time Parameters for Homogeneous Synchronous Dataflow Graphs

Authors
Ali, HI; Akesson, B; Pinho, LM;

Publication
23RD EUROMICRO INTERNATIONAL CONFERENCE ON PARALLEL, DISTRIBUTED, AND NETWORK-BASED PROCESSING (PDP 2015)

Abstract
Many embedded multi-core systems incorporate both dataflow applications with timing constraints and traditional real-time applications. Applying real-time scheduling techniques on such systems provides real-time guarantees that all running applications will execute safely without violating their deadlines. However, to apply traditional real-time scheduling techniques on such mixed systems, a unified model to represent both types of applications running on the system is required. Several earlier works have addressed this problem and solutions have been proposed that address acyclic graphs, implicit-deadline models or are able to extract timing parameters considering specific scheduling algorithms. In this paper, we present an algorithm for extracting real-time parameters (offsets, deadlines and periods) that are independent of the schedulability analysis, other applications running in the system, and the specific platform. The proposed algorithm: 1) enables applying traditional real-time schedulers and analysis techniques on cyclic or acyclic Homogeneous Synchronous Dataflow (HSDF) applications with periodic sources, 2) captures overlapping iterations, which is a main characteristic of the execution of dataflow applications, 3) provides a method to assign offsets and individual deadlines for HSDF actors, and 4) is compatible with widely used deadline assignment techniques, such as NORM and PURE. The paper proves the correctness of the proposed algorithm through formal proofs and examples.

2015

Evaluating Software Engineers' Acceptance of a Technique and Tool for Web Usability Inspection

Authors
Rivero Cabrejos, LJE; Rizzo Vincenzi, AM; Maldonado, JC; Conte, T;

Publication
SEKE

Abstract
Usability is related to software quality, improving its ability to be understood, operated and attractive to users. We proposed the Design Usability Evaluation (DUE) technologies to allow identifying usability problems earlier in the development of Web applications, through the inspection of mockups. While we found that the DUE technique and tool were effective and efficient in the identification of usability problems, we saw the need to investigate their acceptance in practitioners' work environment. This paper reports the results from a study evaluating the acceptance of the DUE technologies from the point of view of software engineers. We asked questions based on the indicators from the Technology Acceptance Model and identified that a majority of the software engineers who participated in the study: (a) found the DUE technologies useful and easy to use for supporting the usability inspection process; and (b) would regularly use the DUE technologies for future inspections in their job. Nevertheless, the practitioners indicated that the technique should be refined in order to reduce the ambiguity and repetition of some of its items, while the tool should become more intuitive.

2015

Special Issue Robtica 2014

Authors
Lau, N; Moreira, AP; Ventura, R; Faria, BM;

Publication
JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS

Abstract

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