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Publicações

Publicações por CRAS

2014

MOVIMENTOS DE VERTENTE NO NORTE DE PORTUGAL: IMPORTÂNCIA DO COMPORTAMENTO HIDROLÓGICO DAS FORMAÇÕES SUPERFICIAIS

Autores
Bateira, CVdM; Soares, LMPM; Rodrigues, DMM; Moura, RMM; Teixeira, MAdC; Santos, MSM;

Publicação
RBG - Revista Brasileira de Geomorfologia

Abstract

2014

Investigating Landfill Contamination by Visualizing Geophysical Data

Autores
Goncalves, V; Dias, P; Fontoura, MJ; Moura, R; Santos, BS;

Publicação
IEEE COMPUTER GRAPHICS AND APPLICATIONS

Abstract
Geophysical experts aimed to establish a method to identify contamination by landfill leakage without chemically analyzing subsoil samples, which is time-consuming and expensive. To that end, researchers developed a software package that let the experts create 3D visualizations of geophysical data acquired around the landfill and apply statistical analysis to detect anomalous values. The data used, electrical resistivity, are typically sparse. So, the application employs kriging to interpolate the data and provide a volumetric representation of the subsoil resistivity. To avoid invalid conclusions, the visualization also represents uncertainty. The application enabled the experts to better understand the phenomenon and to develop and validate their method. Their evaluation of the application indicated that it helped them throughout the method's development and significantly eased their workload. © 2014 IEEE.

2014

High Data Rate Acoustic Modem for Underwater Aplications

Autores
Martins, MS; Pinto, N; Carmo, JP; Cabral, J;

Publicação
2014 International Telecommunications Symposium (ITS)

Abstract
The development of an underwater wireless communication systems is becoming a research and a technological priority due to the increasing demand for exploring the potential of oceans in fields such as pharmaceutics, oil, minerals, environmental and biodiversity. However, underwater wireless communications still fail to ensure high data-rate connections which support real time applications. In this work a low power high data-rate acoustic modem is presented, based on a piezoelectric poly (vinylidene fluoride) polymer as a transducer and a Xilinx Field Programmable Gate Array (FPGA) that can be programmed to work with different types of modulations. The system has been validated by the implementation of a full duplex point-to-point communication at 1 Mbps using On-Off Keying (OOK) modulation with a 1 MHz single carrier and it represents a major advance in the state of the art and a breakthrough in underwater acoustic communications, being the first to show the possibility to achieve data rates up to 1Mbps. It was successfully tested with a 1 Mbps rate, achieving a 3x10(-3) Bit Error Rate (BER) using just 1.4 mu W of power consumption per bit.

2014

Development of a 1 Mbps Low Power Acoustic Modem for Underwater Communications

Autores
Martins, MS; Pinto, N; Rocha, G; Cabral, J; Laceros Mendez, SL;

Publicação
2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)

Abstract
Underwater wireless communication systems are becoming a priority in terms of research and technological development due to the increasing demand for exploring the oceans in areas such as pharmaceutical, oil, minerals, environmental and biodiversity. This demand is increasing exponentially with the need for high data rate and near-real-time communications. In this work an underwater low power acoustic modem to operate over tens of meters, achieving a maximum data rate of 1 Mbps, is presented. This solution allows for reprogramming the digital signal processing block enabling the use of different types of digital modulations in order to improve the modem's performance. The system is based on a poly(vinylidene fluoride) PVDF ultrasonic emitter transducer which is capable of sending high quality signals needed for digital modulations with high symbol rates per carrier period. BPSK, BFSK and OOK modulations have been tested. The results registered were 3x10(-3) BER with 1 Mbps OOK, 2.3x10-5 with 512 kbps and 1x10-8 with 256 kbps.

2013

Development of an Unmanned Capsule for LargeScale Maritime Search and Rescue

Autores
Matos, A; Silva, E; Cruz, N; Alves, JC; Almeida, D; Pinto, M; Martins, A; Almeida, J; Machado, D;

Publicação
2013 OCEANS - SAN DIEGO

Abstract
This paper describes the development and testing of a robotic capsule for search and rescue operations at sea. This capsule is able to operate autonomously or remotely controlled, is transported and deployed by a larger USV into a determined disaster area and is used to carry a life raft and inflate it close to survivors in large-scale maritime disasters. The ultimate goal of this development is to endow search and rescue teams with tools that extend their operational capability in scenarios with adverse atmospheric or maritime conditions.

2013

A FRAMEWORK FOR HARDWARE CELLULAR GENETIC ALGORITHMS: AN APPLICATION TO SPECTRUM ALLOCATION IN COGNITIVE RADIO

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

Publicação
2013 23RD INTERNATIONAL CONFERENCE ON FIELD PROGRAMMABLE LOGIC AND APPLICATIONS (FPL 2013) PROCEEDINGS

Abstract
The genetic algorithm (GA) is an optimization metaheuristic that relies on the evolution of a set of solutions (population) according to genetically inspired transformations. In the variant of this technique called cellular GA, the evolution is done separately for subgroups of solutions. This paper describes a hardware framework capable of efficiently supporting custom accelerators for this metaheuristic. This approach builds a regular array of problem-specific processing elements (PEs), which perform the genetic evolution, connected to shared memories holding the local subpopulations. To assist the design of the custom PEs, a methodology based on highlevel synthesis from C++ descriptions is used. The proposed architecture was applied to a spectrum allocation problem in cognitive radio networks. For an array of 5x5 PEs in a Virtex-6 FPGA, the results show a minimum speedup of 22x compared to a software version running on a PC and a speedup near 2000x over a MicroBlaze soft processor.

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