26 resultados para Parallel programming (computer)
em Repositório Científico do Instituto Politécnico de Lisboa - Portugal
Resumo:
A novel high throughput and scalable unified architecture for the computation of the transform operations in video codecs for advanced standards is presented in this paper. This structure can be used as a hardware accelerator in modern embedded systems to efficiently compute all the two-dimensional 4 x 4 and 2 x 2 transforms of the H.264/AVC standard. Moreover, its highly flexible design and hardware efficiency allows it to be easily scaled in terms of performance and hardware cost to meet the specific requirements of any given video coding application. Experimental results obtained using a Xilinx Virtex-5 FPGA demonstrated the superior performance and hardware efficiency levels provided by the proposed structure, which presents a throughput per unit of area relatively higher than other similar recently published designs targeting the H.264/AVC standard. Such results also showed that, when integrated in a multi-core embedded system, this architecture provides speedup factors of about 120x concerning pure software implementations of the transform algorithms, therefore allowing the computation, in real-time, of all the above mentioned transforms for Ultra High Definition Video (UHDV) sequences (4,320 x 7,680 @ 30 fps).
Resumo:
Hyperspectral imaging has become one of the main topics in remote sensing applications, which comprise hundreds of spectral bands at different (almost contiguous) wavelength channels over the same area generating large data volumes comprising several GBs per flight. This high spectral resolution can be used for object detection and for discriminate between different objects based on their spectral characteristics. One of the main problems involved in hyperspectral analysis is the presence of mixed pixels, which arise when the spacial resolution of the sensor is not able to separate spectrally distinct materials. Spectral unmixing is one of the most important task for hyperspectral data exploitation. However, the unmixing algorithms can be computationally very expensive, and even high power consuming, which compromises the use in applications under on-board constraints. In recent years, graphics processing units (GPUs) have evolved into highly parallel and programmable systems. Specifically, several hyperspectral imaging algorithms have shown to be able to benefit from this hardware taking advantage of the extremely high floating-point processing performance, compact size, huge memory bandwidth, and relatively low cost of these units, which make them appealing for onboard data processing. In this paper, we propose a parallel implementation of an augmented Lagragian based method for unsupervised hyperspectral linear unmixing on GPUs using CUDA. The method called simplex identification via split augmented Lagrangian (SISAL) aims to identify the endmembers of a scene, i.e., is able to unmix hyperspectral data sets in which the pure pixel assumption is violated. The efficient implementation of SISAL method presented in this work exploits the GPU architecture at low level, using shared memory and coalesced accesses to memory.
Resumo:
In this paper, we develop a fast implementation of an hyperspectral coded aperture (HYCA) algorithm on different platforms using OpenCL, an open standard for parallel programing on heterogeneous systems, which includes a wide variety of devices, from dense multicore systems from major manufactures such as Intel or ARM to new accelerators such as graphics processing units (GPUs), field programmable gate arrays (FPGAs), the Intel Xeon Phi and other custom devices. Our proposed implementation of HYCA significantly reduces its computational cost. Our experiments have been conducted using simulated data and reveal considerable acceleration factors. This kind of implementations with the same descriptive language on different architectures are very important in order to really calibrate the possibility of using heterogeneous platforms for efficient hyperspectral imaging processing in real remote sensing missions.
Resumo:
Este Trabalho refere-se ao Projecto de Execuo de Fundaes e Estruturas de uma Ponte Rodoviria em beto armado pr-esforado, realizado no mbito do Trabalho Final de Mestrado em Engenharia Civil Especializao em Estruturas, do Instituto Superior de Engenharia de Lisboa. O Projecto de Execuo composto de Peas Escritas e Peas Desenhadas. Nas Peas Escritas esto includos: Memria Justificativa e Descritiva; Clculos Justificativos e Anexos. A ponte composta por dois tabuleiros paralelos com 10,28m de largura cada um e afastados entre si de 0,10m. A obra constituda de 8 tramos; os tramos correntes com 31m de comprimento e os tramos extremos com 25 e 20m de comprimento, perfazendo um comprimento total de 231m. A obra foi parcialmente isolada dos sismos pela introduo, em todos os pilares, de aparelhos de apoio de elevado amortecimento ssmico do tipo HDRB (High Damping Rubber Bearings). Encontram-se particularmente discriminadas e detalhadas neste projecto as seguintes situaes: - Clculo do Pr-esforo e respectivas perdas; - Aco das sobrecargas rodovirias; - Diferena de comportamento da obra na entrada em servio e no longo prazo; - Anlise ssmica e do isolamento ssmico; - Estudo dos efeitos diferidos: retraco e fluncia. Tendo as abordagens de clculo e as verificaes de segurana seguido a regulamentao nacional em vigor, nomeadamente RSA e REBAP, foi no entanto feita uma aproximao s regras do Capacity Design previstas no EC8, em que se privilegia a actuao do projectista sobre o comportamento da estrutura, procurando uma resposta no linear da mesma, visando garantir que: - A rotura no ocorrer nos elementos de fundao; - Nos pilares a dissipao de energia se faz atravs de rtulas plsticas, evitando-se roturas associadas a esforos transversos. A aplicao destas regras neste Projecto demonstrou haver um agravamento substancial na definio dos esforos a que devem resistir alguns dos componentes da estrutura, designadamente os pilares e as fundaes, originando solues de seces de beto e armaduras bem mais exigentes do que aqueles que resultariam da simples verificao de segurana, pela comparao entre esforos actuante e esforos resistentes seco a seco, imposta pela actual regulamentao nacional.
Resumo:
O presente trabalho teve como principal objectivo o desenvolvimento de um analisador de vibraes de dois canais baseado em computador, para a realizao de diagnstico no mbito do controlo de condio de mquinas. Foi desenvolvida uma aplicao num computador comum, no software LabVIEW, que atravs de transdutores de acelerao do tipo MEMS conectados via USB, faz a recolha de dados de vibrao e procede ao seu processamento e apresentao ao utilizador. As ferramentas utilizadas para o processamento de dados so ferramentas comuns encontradas em vrios analisadores de vibraes disponveis no mercado. Estas podem ser: grficos de espectro de frequncia, sinal no tempo, cascata ou valores de nvel global de vibrao, entre outras. Apesar do analisador desenvolvido no apresentar inovao nas ferramentas de anlise adoptadas, este pretende ser distinguido pelo baixo custo, simplicidade e carcter didctico. Este trabalho vem evidenciar as vantagens, desvantagens e potencialidades de um analisador desta natureza. So tiradas algumas concluses quanto sua capacidade de diagnstico de avarias, capacidades como ferramenta didctica, sensores utilizados e linguagem de programao escolhida. Como concluses principais, o trabalho revela que os sensores escolhidos no so os indicados para efectuar o diagnstico de avarias em ambiente industrial, contudo so ideais para tornar este analisador numa boa ferramenta didctica e de treino.
Resumo:
O trabalho que se apresenta incide sobre o estudo aerodinmico das ps de uma turbina elica de pequeno porte, com vista simplificao geomtrica, de forma a que estas sejam baratas e de fcil concepo. A teoria da quantidade de movimento do elemento de p (BEMT), que o modelo de referncia para o projecto e anlise aerodinmica das ps das turbinas elicas, foi utilizada neste trabalho de forma a projectar e analisar aerodinamicamente as ps da turbina. Sendo assim, desenvolveu-se um programa computacional em MATLAB, denominado de Turbina, de forma a implementar a teoria BEM. Introduzindo os dados dos parmetros de projecto no programa (potncia requerida, o nmero de ps, velocidade do vento, a TSR e o tipo de perfil alar), obtm-se os parmetros geomtricos das ps (distribuio da corda ao longo da envergadura, o raio da p e a distribuio da toro da p), os parmetros aerodinmicos e de desempenho. Uma p ideal foi calculada e de seguida foi modificada de forma a obter-se uma p simples e menos carregada aerodinamicamente. Introduzidas as modificaes na geometria da p ideal, obtiveram-se duas configuraes distintas. Uma configurao linear, onde a distribuio da corda e do ngulo de toro se tornam lineares, e outra configurao bi-linear, onde a distribuio da corda continua linear mas o ngulo de toro se torna bi-linear, isto , a p composta por dois troos onde cada troo apresenta uma distribuio linear do ngulo de toro geomtrica. As concluses demonstram que a configurao bi-linear uma boa alternativa a configurao ideal, apresentando uma reduo do desempenho do rotor de 2.8% para um aumento do raio da p em 1.41%, para se obter a mesma potncia da configurao ideal. A anlise aos perfis alares, utilizados neste trabalho, foi efectuada a partir dos programas comerciais ICEM e FLUENT. De forma a automatizar a anlise de CFD, trs programas foram desenvolvidos utilizando a linguagem de programao C. Os programas so denominados de Malha2D, Calcula_Coeficientes e Plot_Graficos. Finalmente, um estudo paramtrico foi feito de forma a avaliar a influncias das variveis de projecto no desempenho geral da turbina.
Resumo:
This paper is on the problem of short-term hydro, scheduling, particularly concerning head-dependent cascaded hydro systems. We propose a novel mixed-integer quadratic programming approach, considering not only head-dependency, but also discontinuous operating regions and discharge ramping constraints. Thus, an enhanced short-term hydro scheduling is provided due to the more realistic modeling presented in this paper. Numerical results from two case studies, based on Portuguese cascaded hydro systems, illustrate the proficiency of the proposed approach.
Resumo:
Liver steatosis is a common disease usually associated with social and genetic factors. Early detection and quantification is important since it can evolve to cirrhosis. In this paper, a new computer-aided diagnosis (CAD) system for steatosis classification, in a local and global basis, is presented. Bayes factor is computed from objective ultrasound textural features extracted from the liver parenchyma. The goal is to develop a CAD screening tool, to help in the steatosis detection. Results showed an accuracy of 93.33%, with a sensitivity of 94.59% and specificity of 92.11%, using the Bayes classifier. The proposed CAD system is a suitable graphical display for steatosis classification.
Resumo:
International Conference with Peer Review 2012 IEEE International Conference in Geoscience and Remote Sensing Symposium (IGARSS), 22-27 July 2012, Munich, Germany
Resumo:
Dissertao para obteno do grau de Mestre em Engenharia Electrotcnica Ramo Automao e Electrnica Industrial
Avaliao da caracterizao de leses em mamografia com recurso a sistemas CAD (Computer-Aided Diagnosis)
Resumo:
Os sistemas Computer-Aided Diagnosis (CAD) auxiliam a deteo e diferenciao de leses benignas e malignas, aumentando a performance no diagnstico do cancro da mama. As leses da mama esto fortemente correlacionadas com a forma do contorno: leses benignas apresentam contornos regulares, enquanto as leses malignas tendem a apresentar contornos irregulares. Desta forma, a utilizao de medidas quantitativas, como a dimenso fractal (DF), pode ajudar na caracterizao dos contornos regulares ou irregulares de uma leso. O principal objetivo deste estudo verificar se a utilizao concomitante de 2 (ou mais) medidas de DF uma tradicionalmente utilizada, a qual foi designada por DF de contorno; outra proposta por ns, designada por DF de rea e ainda 3 medidas obtidas a partir destas, por operaes de dilatao/eroso e por normalizao de uma das medidas anteriores, melhoram a capacidade de caracterizao de acordo com a escala BIRADS (Breast Imaging Reporting and Data System) e o tipo de leso. As medidas de DF (DF contorno e DF rea) foram calculadas atravs da aplicao do mtodo box-counting, diretamente em imagens de leses segmentadas e aps a aplicao de um algoritmo de dilatao/eroso. A ltima medida baseia-se na diferena normalizada entre as duas medidas DF de rea antes e aps a aplicao do algoritmo de dilatao/eroso. Os resultados demonstram que a medida DF de contorno uma ferramenta til na diferenciao de leses, de acordo com a escala BIRADS e o tipo de leso; no entanto, em algumas situaes, ocorrem alguns erros. O uso combinado desta medida com as quatro medidas propostas pode melhorar a classificao das leses.
Resumo:
The study of biosignals has had a transforming role in multiple aspects of our society, which go well beyond the health sciences domains to which they were traditionally associated with. While biomedical engineering is a classical discipline where the topic is amply covered, today biosignals are a matter of interest for students, researchers and hobbyists in areas including computer science, informatics, electrical engineering, among others. Regardless of the context, the use of biosignals in experimental activities and practical projects is heavily bounded by the cost, and limited access to adequate support materials. In this paper we present an accessible, albeit versatile toolkit, composed of low-cost hardware and software, which was created to reinforce the engagement of different people in the field of biosignals. The hardware consists of a modular wireless biosignal acquisition system that can be used to support classroom activities, interface with other devices, or perform rapid prototyping of end-user applications. The software comprehends a set of programming APIs, a biosignal processing toolbox, and a framework for real time data acquisition and postprocessing. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
Resumo:
This paper is on the maximization of total profit in a day-ahead market for a price-taker producer needing a short-term scheduling for wind power plants coordination with concentrated solar power plants, having thermal energy storage systems. The optimization approach proposed for the maximization of profit is a mixed-integer linear programming problem. The approach considers not only transmission grid constraints, but also technical operating constraints on both wind and concentrated solar power plants. Then, an improved short-term scheduling coordination is provided due to the more accurate modelling presented in this paper. Computer simulation results based on data for the Iberian wind and concentrated solar power plants illustrate the coordination benefits and show the effectiveness of the approach.
Resumo:
This letter presents a new parallel method for hyperspectral unmixing composed by the efficient combination of two popular methods: vertex component analysis (VCA) and sparse unmixing by variable splitting and augmented Lagrangian (SUNSAL). First, VCA extracts the endmember signatures, and then, SUNSAL is used to estimate the abundance fractions. Both techniques are highly parallelizable, which significantly reduces the computing time. A design for the commodity graphics processing units of the two methods is presented and evaluated. Experimental results obtained for simulated and real hyperspectral data sets reveal speedups up to 100 times, which grants real-time response required by many remotely sensed hyperspectral applications.
Resumo:
Physical computing has spun a true global revolution in the way in which the digital interfaces with the real world. From bicycle jackets with turn signal lights to twitter-controlled christmas trees, the Do-it-Yourself (DiY) hardware movement has been driving endless innovations and stimulating an age of creative engineering. This ongoing (r)evolution has been led by popular electronics platforms such as the Arduino, the Lilypad, or the Raspberry Pi, however, these are not designed taking into account the specific requirements of biosignal acquisition. To date, the physiological computing community has been severely lacking a parallel to that found in the DiY electronics realm, especially in what concerns suitable hardware frameworks. In this paper, we build on previous work developed within our group, focusing on an all-in-one, low-cost, and modular biosignal acquisition hardware platform, that makes it quicker and easier to build biomedical devices. We describe the main design considerations, experimental evaluation and circuit characterization results, together with the results from a usability study performed with volunteers from multiple target user groups, namely health sciences and electrical, biomedical, and computer engineering. Copyright 2014 SCITEPRESS - Science and Technology Publications. All rights reserved.