Optimization of breast tomosynthesis image reconstruction using parallel computing

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.

Improvement of Lipton’s business model through wholesalers and traditional supermarkets channel

Field Lab in Entrepreneurial Innovative Ventures

Numerical modelling of compound channel flow

Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/64337/2009 ; projects PTDC/ECM/70652/2006, PTDC/ECM/117660/2010 and RECI/ECM-HID/0371/2012

A public transport bus assignment problem: parallel metaheuristics assessment

Combinatorial Optimization Problems occur in a wide variety of contexts and generally are NP-hard problems. At a corporate level solving this problems is of great importance since they contribute to the optimization of operational costs. In this thesis we propose to solve the Public Transport Bus Assignment problem considering an heterogeneous fleet and line exchanges, a variant of the Multi-Depot Vehicle Scheduling Problem in which additional constraints are enforced to model a real life scenario. The number of constraints involved and the large number of variables makes impracticable solving to optimality using complete search techniques. Therefore, we explore metaheuristics, that sacrifice optimality to produce solutions in feasible time. More concretely, we focus on the development of algorithms based on a sophisticated metaheuristic, Ant-Colony Optimization (ACO), which is based on a stochastic learning mechanism. For complex problems with a considerable number of constraints, sophisticated metaheuristics may fail to produce quality solutions in a reasonable amount of time. Thus, we developed parallel shared-memory (SM) synchronous ACO algorithms, however, synchronism originates the straggler problem. Therefore, we proposed three SM asynchronous algorithms that break the original algorithm semantics and differ on the degree of concurrency allowed while manipulating the learned information. Our results show that our sequential ACO algorithms produced better solutions than a Restarts metaheuristic, the ACO algorithms were able to learn and better solutions were achieved by increasing the amount of cooperation (number of search agents). Regarding parallel algorithms, our asynchronous ACO algorithms outperformed synchronous ones in terms of speedup and solution quality, achieving speedups of 17.6x. The cooperation scheme imposed by asynchronism also achieved a better learning rate than the original one.

How can Biotherm grow in the selective skincare channel in Portugal?

Branding Lab

Consulting project for Câmara Municipal de Cascais street vending in Portugal- creation and development of a new sales channel

Field lab: Consulting lab

Omni-channel retail strategies in the luxury world

It’s impossible to neglect the changes that internet and e-commerce caused in the retail sector, by increasing customers’ expectations and forcing retailers to adapt the business to the new digital era. Internet is characterized by the increase in accessibility to everyone, which can be good or not so. For instance, luxury products rely on the sense of exclusivity, instead of being accessible to everyone. Hence, internet represents a challenge for luxury brands once, although they are able to provide a fullness service to their customers, they need to maintain the exclusiveness in which luxury is sustained. Consequently, the appearance of omni-channel was more than a challenge for the luxury sector, in particular, given the need to provide a full integrated experience through different channels. The aim of this dissertation is to find out how important is omni-channel, even in the luxury industry, and how it’s actually implemented based on the case of one of the most successful companies on luxury fashion e-commerce industry – Farfetch. Even though the company started in London, its founder is a Portuguese entrepreneur, and it’s in Portugal where most of its employees work, divided in two offices – Guimarães e Porto. Therefore, a literature review was written on relevant concepts and ideas about luxury, e-commerce and the different channels’ approaches. There were formulated five propositions that were after discussed according to the information gathered about the company and its strategies. In the end, it was possible to identify which propositions are in accordance with theory and which are not, as well as understand which are the most important strategies and trends about omni-channel in the luxury fashion e-commerce sector.

How can digital help biotherm growing in the Portuguese selective skincare channel?

Branding Lab