Analytical querying with typed linear algebra: integration with MonetDB

Dissertação de mestrado integrado em Informatics EngineeringCurrent digital transformations in society heavily rely on safe, easy-to-use, high-performance data storage and analysis for smart decision taking. This triggered the need for efficient analytical querying solutions and the columnar database model is increasingly regarded as the most efficient model for data organization in large data banks. MonetDB is a pioneer in the column-wise database model and is currently at the forefront of high performance DBMS engine. A Linear Algebra Querying (LAQ) engine, using a columnar database paradigm and strongly inspired on Typed Linear Algebra (TLA), was developed in a former MSc. dissertation, with a prototype Web interface. Performance benchmarking of this engine showed it outperformed conventional referenced DBMS but it failed to beat MonetDB’s performance. This dissertation aims to improve the performance of the LAQ engine by following a different path: instead of a standalone engine, the new approach implements the engine on top of MonetDB extended with RMA (Relational Matrix Algebra) and inspired by the TLA approach. This enables the use of LAQ scripting to replace the main stream relational algebra query language approach given by SQL. Matrix operations commonly used in LAQ/TLA, such as matrix-matrix multiplication, Khatri-Rao product or Hadamard-Schur product, had to be implemented in RMA to shift from the relational algebra paradigm to TLA. A thorough analysis of the MonetDB/RMA showed the need to implement key TLA operators that are not available at the frontend. Such operators were implemented and successfully tested and validated, paving the way to future benchmarking its performance with TPC-H/OLAP queries and consequent fine tuning of the engine.Atualmente, as transformações digitais na sociedade confiam fortemente no armazenamento e na análise de dados seguros, fáceis de usar e de alto desempenho para tomadas de decisão inteligentes. Este facto desencadeou a necessidade de soluções de consultas analíticas eficientes, em que o modelo de bases de dados colunar é cada vez mais considerado o modelo mais eficiente para organização de dados em grandes bancos de dados. MonetDB é um sistema pioneiro no modelo de bases de dados colunar e atualmente está na vanguarda de DBMS’s de alto desempenho. Um motor Linear Algebra Querying (LAQ), que usa o paradigma de bases de dados colunar e fortemente inspirado em Álgebra Linear Tipada (TLA), foi desenvolvido numa antiga dissertação de mestrado em Engenharia Informática. O benchmarking do desempenho deste motor mostrou que supera DBMS tradicionais, mas não conseguiu superar o desempenho do MonetDB. Esta dissertação visa melhorar o desempenho do motor LAQ seguindo um caminho diferente: em vez de um motor autónomo, a nova abordagem implementa o motor sobre o motor do MonetDB estendido com RMA (Álgebra Relacional Matricial) e inspirado na abordagem de TLA. Isto permite o uso de scripts LAQ para substituir a abordagem da linguagem de consulta de álgebra relacional fornecida pelo SQL. Operações de matrizes comumente usadas em LAQ / TLA, como multiplicação de matrizes, produto Khatri-Rao ou produto Hadamard-Schur, tiveram de ser implementadas em RMA para mudar do paradigma da álgebra relacional para TLA. Uma análise completa do MonetDB / RMA mostrou a necessidade de implementar os principais operadores de TLA que não estão disponíveis no front-end. Esses operadores foram implementados, testados e validados com sucesso, abrindo caminho para um futuro benchmarking do seu desempenho com queries TPC-H / OLAP e consequente, ajuste do motor

The Effects of 3D Printing Parameters and Surface Treatments on Convective Heat Transfer Performance

Additive manufacturing technology and applications have quickly expanded in many industries over the last five years. As additive manufacturing is studied and refined, improvements in resolution and strength have helped propel further growth of the industry. This study focuses on an additive manufacturing technology called fused filament fabrication (FFF). FFF involves the extrusion and layer-by-layer deposition of a molten thermoplastic material to create the desired part. One potential new application of fused filament fabrication is the manufacture of heat exchangers and heat sinks. This study focuses on developing baseline experimental data related to convective heat transfer coefficients over surfaces of commonly used polymers in FFF 3d printing while varying printing parameters and surface treatments of the samples. A copper pipe containing two cartridge heaters was placed inside the ABS test samples with two thermocouples placed at the surface of the 3d printed material to measure the surface temperature of the cylinder. The samples were tested inside a wind tunnel to measure the effects of surface roughness and printing parameters on heat transfer over a range of velocities. Samples with different printing parameters were tested first. Parts with layer heights (LH) of 0.1 mm, 0.2 mm and 0.3 mm were printed. As the layer height increases the roughness also increased. Sample 1 of LH = 0.1 mm had a roughness of 9.72 μm and a heat transfer coefficient of 72 W/m2-K and sample 1 of LH = 0.3 mm had a roughness of 28.83 μm and a heat transfer coefficient of 85 W/m2-K, with fans operating at 12V. Surface treatment, such as acetone smoothing, sanding and sanding/acetone-smoothing were performed in other to reduce surface roughness. The acetone smoothing process affected more the samples with smaller layer heights. Sample 1 of LH = 0.2 mm had a roughness reduced to 11.43 μm and a heat transfer coefficient of 71 W/m2-K. Sanding and sanding/acetone-smoothing process recorded the smallest values for roughness, while recording the highest values for heat transfer coefficient. Sanded sample 2 of LH = 0.3 had a heat transfer coefficient of 101 W/m2-K and roughness of 4.35 μm

Routing cost optimization in Multi Overlay Robust Networks

In the present work we solve the problem of data flow routing in Multi-Overlay Robust Networks (MORN) while aiming to minimize its routing cost. This kind of networks are typically IP/MPLS Data Network deployed over an SDH/DWDM transport infrastructure. Through the IP/MPLSMulti-Layer Data Network different kinds of services having a wide variety of quality of service requirements are delivered. Those services are being transported by an SDH/DWDM Transport Network which has different transport capacities. In this network, routing cost depends not only on the assigned transport capacity but also in the technology that it uses. Our problem seeks not only to route data flows through Data and Transport Networks but also to optimize routing costs and the reliability of the network. The inputs of our problem are the topology of the Data and Transport networks as well as the budget that the network operator has in order to improve its network routing costs and reliability. We will assume that the operator can only use that budget for installing new links between existing transport nodes. The output of the problem is the data flow routing in the Data and Transport Networks and its associated cost. Routing in the Transport Network is calculated not only in the nominal scenario - when all the Transport Network links are up and running - but also in each single transport link failure case.En el presente trabajo se resuelve el problema de rutear flujos de datos en una Red Multi- Capa Robusta (MORN por sus siglas en inglés), mientras que se trata de minimizar el costo asociado a su ruteo. Este tipo de redes son generalmente redes de datos IP/MPLS desplegadas sobre una infraestructura de transporte SDH/DWDM. Sobre la red de datos IP/MPLS se cursan distintos servicios con diferentes requerimientos de calidad de servicio (QoS). Los servicios de la Red de Datos son transportados por la red SDH/DWDM la cual tiene distintas capacidades de transporte. En éste tipo de redes el costo asociado al transporte depende no solo de la capacidad asignada para el transporte sino que también depende de la tecncología utilizada para transportar dicha capacidad. En el problema no sólo se busca enrutar flujos de datos a través de las Redes de Datos y Transporte sino que también se busca optimizar los costos de ruteo y la confiabilidad de la red. Como punto de partida, el problema toma como información la topología de las Redes de Datos y Transporte así como cierto presupuesto que el operador de la red posee para poder mejorar los costos de ruteo y la confiabilidad de su red. Asumiremos que dicho presupuesto solo puede ser utilizado para instalar nuevos enlaces entre los nodos existentes en la Red de Transporte. La salida del problema es el ruteo de los flujos de datos tanto en la Red de Datos como en la de Transporte, así como el costo asociado a dicho ruteo. El ruteo en la Red de Transporte se calcula no solo en el escenario nominal - cuando todos los enlaces de la Red de Transporte están funcionales - sino que también en cada escenario de falla simple en sus enlaces

Consistent Gravitationally-Coupled Spin-2 Field Theory

Inspired by the translational gauge structure of teleparallel gravity, the theory for a fundamental massless spin-2 field is constructed. Accordingly, instead of being represented by a symmetric second-rank tensor, the fundamental spin-2 field is assumed to be represented by a spacetime (world) vector field assuming values in the Lie algebra of the translation group. The flat-space theory naturally emerges in the Fierz formalism and is found to be equivalent to the usual metric-based theory. However, the gravitationally coupled theory, with gravitation itself described by teleparallel gravity, is shown not to present the consistency problems of the spin-2 theory constructed on the basis of general relativity.Comment: 16 pages, no figures. V2: Presentation changes, including addition of a new sub-section, aiming at clarifying the text; version accepted for publication in Class. Quantum Grav

Diluted planar ferromagnets: nonlinear excitations on a non-simply connected manifold

We study the behavior of magnetic vortices on a two-dimensional support manifold being not simply connected. It is done by considering the continuum approach of the XY-model on a plane with two disks removed from it. We argue that an effective attractive interaction between the two disks may exist due to the presence of a vortex. The results can be applied to diluted planar ferromagnets with easy-plane anisotropy, where the disks can be seen as nonmagnetic impurities. Simulations are also used to test the predictions of the continuum limit.Comment: 5 pages, 6 figure

Earning the Keys to the Kingdom: Students’ Language Awareness, Identity and Representations of English-Speaking Others

The present linguistic reality involves finding ways of communication in the globalized environment, where people move all around the world in order to find work, learn, or share experiences. One issue arising from English language teaching is that it has mainly overlooked teaching culture across the curriculum, thus allowing the increase of negative attitudes and stereotypes. This paper is set out to determine to what extent English language teaching (ELT) materials demonstrate the traits of the English-speaking Other, it what ways children are accessing the target ‘Kingdom’, and which are the best teaching strategies to provide them with the keys to the target world. Anchoring our perspective in CLIL and the 4 Cs, this study looks at ways of developing cutting-edge syllabi to develop intercultural awareness and preventing stereotypes. Findings from the application of the syllabi and resulting from an analysis of the cultural content of two internationally distributed ELT textbooks are reported. The present research put in evidence that cultural aspects are practically absent from the analyzed textbooks, thus lacking a key dimension in English Language Teaching and Education. Therefore, some recommendations for future textbook writers and EFL classroom practice are suggested

INNOVATION AND THE WARLIKE PHENOMENON

O presente artigo busca mostrar as conexões entre a história do fenômeno bélico, ou simplesmente história da guerra, com a discussão sobre a inovação. Neste sentido, o artigo pretende mostrar algumas evoluções técnicas e tecnológicas e quais foram seus impactos nas guerras e na própria história humana. Dividiu-se a discussão em três momentos. No primeiro deles apresentou-se os elementos teóricos mais relevantes da guerra à luz dos trabalhos de Clausewitz. Em um segundo momento, tratou-se brevemente da evolução do fenômeno bélico ao longo da história humana, com foco em algumas transformações técnicas e tecnológicas de fins do século XIX e início do século XX. A I Guerra Mundial foi objeto de análise em uma maior profundidade. Em um terceiro momento, foi discutido como as inovações analisadas se relacionam com as categorias propostas por Tidd, Bessant e Pavit.