Symplectic resolutions, Lefschetz property and formality

We introduce a method to resolve a symplectic orbifold into a smooth symplectic manifold. Then we study how the formality and the Lefschetz property of the symplectic resolution are compared with that of the symplectic orbifold. We also study the formality of the symplectic blow-up of a symplectic orbifold along symplectic submanifolds disjoint from the orbifold singularities. This allows us to construct the first example of a simply connected compact symplectic manifold of dimension 8 which satisfies the Lefschetz property but is not formal, therefore giving a counter-example to a conjecture of Babenko and Taimanov.Comment: 21 pages, no figure

Una visió actual a l'estat de la dona en les enginyeries

Aquest article analitza l’efecte del gènere en les vocacions tecnològiques estudiant quins són els factors que provoquen el gran desequilibri entre la presència d’homes i de dones en els estudis tècnics. Es mostren dades estadístiques de la situació actual i la seva evolució i s’expliquen accions realitzades per potenciar la presència de més dones en els estudis tècnics.Peer ReviewedPostprint (published version

On non-formality of a simply-connected symplectic 8-manifold

We show an alternative construction of the first example of a simply-connected compact symplectic non-formal 8-manifold given in arXiv:math/0506449. We also give an alternative proof of its non-formality using higher order Massey products.Comment: 10 pages; to appear in American Institute of Physics Conference Proceedings. Proceedings of the XVI International Fall Workshop on Geometry and Physics, Lisboa 200

Technology-Enhanced Learning (TEL) tools to improve computational thinking skills

The common and easy access to technological devices has led to the rapid inclusion of technology into the learning process. The development of technical skills, as well as the increasing confidence in computer attitudes, seems to be obvious. We therefore propose to go beyond and advocate the use of TEL to provide specific leadership, multi-tasking and other organizational skills, known as computational thinking, as precisely the main contributions provided by TEL. To support this hypothesis, we present two different experiences. The first, based on high-school students, to introduce young people to technology at the same time as they acquire other demanding skills. The second, with undergraduate Computer Science students, is focused on technology itself to enhance and improve computational thinking skills. A comparison is also made between two populations with different digital profiles in their user skills (general in the first case and engineering biased in the second).Peer ReviewedPostprint (author’s final draft

Ambiences: on-the-fly usage of available resources through personal devices

In smart spaces such as smart homes, computation is embedded everywhere: in toys, appliances, or the home’s infrastructure. Most of these devices provide a pool of available resources which the user can take advantage, interacting and creating a friendly environment. The inherent composability of these systems and other unique characteristics such as low-cost energy, simplicity in module programming, and even their small size, make them a suitable candidate for dynamic and adaptive ambient systems. This research work focuses on what is defined as an “ambience”, a space with a user-defined set of computational devices. A smart-home is modeled as a collection of ambiences, where every ambience is capable of providing a pool of available resources to the user. In turn, the user is supposed to carry one or several personal devices able to interact with the ambiences, taking advantage of his inherent mobility. In this way, the whole system can benefit from resources discovered in the spatial proximity. A software architecture is designed, which is based on the implementation of low-cost algorithms able to detect and update the system when changes in an ambience occur. Ambience middleware implementation works in a wide range of architectures and OSs, while showing a negligible overhead in the time to perform the basic output operations.Peer ReviewedPostprint (published version

Strategies of Domain Decomposition to Partition Mesh-Based Applications onto Computational Grids

In this paper, we evaluate strategies of domain decomposition in Grid environment to solve mesh-basedapplications. We compare the balanced distribution strategy with unbalanced distribution strategies. While the former is acommon strategy in homogenous computing environment (e.g. parallel computers), it presents some problems due tocommunication latency in Grid environments. Unbalanced decomposition strategies consist of assigning less workload toprocessors responsible for sending updates outside the host. The results obtained in Grid environments show that unbalanceddistributions strategies improve the expected execution time of mesh-based applications by up to 53%. However, this is not truewhen the number of processors devoted to communication exceeds the number of processors devoted to calculation in thehost. To solve this problem we propose a new unbalanced distribution strategy that improves the expected execution time up to43%. We analyze the influence of the communication patterns on execution times using the Dimemas simulator.Peer ReviewedPostprint (published version

OS paradigms adaptation to fit new architectures

Future architectures and computer systems will be heterogeneous multi-core models, which will improve their performance, resource utilization and energy consumption. Differences between cores mean different binary formats and specific concerns when dealing with applications. The OS also needs to manage the appropriate information to schedule resources to achieve the optimal performance. In this paper we present a first approach in Linux to allow the application to give information to the OS in order to perform the best resource scheduling for the code characteristics (where it has to run). Based on the continuation model of the Mach microkernel and the device drivers of Unix-Linux system, the kernel can continue the execution flow from one core to another (i.e. from PPE to SPE in the Cell BE case). In this way, the OS can anticipate costly actions (for example, loading code or data) or reserve resources depending on task needs. To reach our target, we adapt the operating system as well as modify the application binary to divide its code parts depending on their characteristics and where they have to run. Experimental work has been done for x86 with MMX extension ISA as well as for PPC and Cell BE.Peer ReviewedPostprint (published version

Aplicação da análise dos modos de falha e seus efeitos ao processo de reclamações da empresa Alvecabo

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia de Gestão IndustrialO presente trabalho incide na aplicação da Análise dos Modos de Falha e seus Efeitos (AMFE) ao processo de reclamações da empresa Alvecabo – Construção Civil e Comunicações S.A.. Iniciou-se este estudo com a recolha de dados referente a reclamações efectuadas, no ano de 2008, por clientes à Portugal Telecom, principal cliente da Alvecabo. Numa primeira fase recorreu-se ao Diagrama de Pareto para identificar o conjunto de reclamações que evidenciassem maior impacto para a empresa, ou seja, uma maior percentagem de ocorrências, tendo sido identificadas cinco, num total de 23 reclamações diferentes (doravante denominadas por modos de falha). Para os cinco modos de falha a estudar, verificaram-se, nos dados facultados pela empresa, todas as possíveis causas que lhes deram origem, e definiram-se, para cada modo de falha, as que contribuíam significativamente para a ocorrência dos problemas. Depois de definidos os modos de falha a analisar e respectivas causas que lhes deram origem, procedeu-se à aplicação da Fase de Avaliação da AMFE, através da qual se calculou o Número de Prioridade de Risco (NPR) para cada uma das causas relativas aos problemas em análise. Posteriormente, aplicou-se o Diagrama de Pareto para todas as causas potenciais de falha e respectivos valores de NPR, de modo a ser possível definir quais deveriam ser analisadas, isto é, para quais delas se iria proceder à segunda fase de aplicação da ferramenta, Fase de Reavaliação e Melhoria. Na Fase de Reavaliação e Melhoria da AMFE, definiram-se acções correctivas para as causas que revelaram uma maior contribuição na ocorrência dos problemas, pelo Diagrama de Pareto, e para as causas cujos valores de índice de Ocorrência e Detecção se revelaram mais elevados. Nesta fase seria suposto avaliar a eficácia das acções de correcção recomendadas, de modo a constatar-se ou não a eficiência da AMFE no processo de reclamações da empresa, no entanto não se reuniram as condições necessárias para que o autor deste estudo o pudesse realizar, pelo que a presente Dissertação pretende apenas criar um registo predecessor a uma futura implementação da ferramenta