45 resultados para constraint optimization
                                
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Dissertação para obtenção do Grau de Doutor em Engenharia Química, especialidade de Engenharia Bioquímica
                                
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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e Computadores
                                
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Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Informática, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
                                
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics
                                
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Tese apresentada para obtenção do Grau de Doutor em Engenharia Civil na especialidade de Reabilitação do Património Edificado, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
                                
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
                                
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Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
                                
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Dissertação para obtenção do Grau de Mestre em Biotecnologia
                                
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Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores
                                
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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores
                                
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
                                
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
                                
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Dissertação para obtenção do Grau de Mestre em Engenharia Informática
                                
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Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica
                                
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Breast cancer is the most common cancer among women, being a major public health problem. Worldwide, X-ray mammography is the current gold-standard for medical imaging of breast cancer. However, it has associated some well-known limitations. The false-negative rates, up to 66% in symptomatic women, and the false-positive rates, up to 60%, are a continued source of concern and debate. These drawbacks prompt the development of other imaging techniques for breast cancer detection, in which Digital Breast Tomosynthesis (DBT) is included. DBT is a 3D radiographic technique that reduces the obscuring effect of tissue overlap and appears to address both issues of false-negative and false-positive rates. The 3D images in DBT are only achieved through image reconstruction methods. These methods play an important role in a clinical setting since there is a need to implement a reconstruction process that is both accurate and fast. This dissertation deals with the optimization of iterative algorithms, with parallel computing through an implementation on Graphics Processing Units (GPUs) to make the 3D reconstruction faster using Compute Unified Device Architecture (CUDA). Iterative algorithms have shown to produce the highest quality DBT images, but since they are computationally intensive, their clinical use is currently rejected. These algorithms have the potential to reduce patient dose in DBT scans. A method of integrating CUDA in Interactive Data Language (IDL) is proposed in order to accelerate the DBT image reconstructions. This method has never been attempted before for DBT. In this work the system matrix calculation, the most computationally expensive part of iterative algorithms, is accelerated. A speedup of 1.6 is achieved proving the fact that GPUs can accelerate the IDL implementation.
 
                    