Distributed learning of CNNs on heterogeneous CPU/GPU architectures

Convolutional Neural Networks (CNNs) have shown to be powerful classification tools in tasks that range from check reading to medical diagnosis, reaching close to human perception, and in some cases surpassing it. However, the problems to solve are becoming larger and more complex, which translates to larger CNNs, leading to longer training times that not even the adoption of Graphics Processing Units (GPUs) could keep up to. This problem is partially solved by using more processing units and distributed training methods that are offered by several frameworks dedicated to neural network training. However, these techniques do not take full advantage of the possible parallelization offered by CNNs and the cooperative use of heterogeneous devices with different processing capabilities, clock speeds, memory size, among others. This paper presents a new method for the parallel training of CNNs that can be considered as a particular instantiation of model parallelism, where only the convolutional layer is distributed. In fact, the convolutions processed during training (forward and backward propagation included) represent from $60$-$90$\% of global processing time. The paper analyzes the influence of network size, bandwidth, batch size, number of devices, including their processing capabilities, and other parameters. Results show that this technique is capable of diminishing the training time without affecting the classification performance for both CPUs and GPUs. For the CIFAR-10 dataset, using a CNN with two convolutional layers, and $500$ and $1500$ kernels, respectively, best speedups achieve $3.28\times$ using four CPUs and $2.45\times$ with three GPUs. Modern imaging datasets, larger and more complex than CIFAR-10 will certainly require more than $60$-$90$\% of processing time calculating convolutions, and speedups will tend to increase accordingly

mfEGRA: Multifidelity Efficient Global Reliability Analysis through Active Learning for Failure Boundary Location

This paper develops mfEGRA, a multifidelity active learning method using data-driven adaptively refined surrogates for failure boundary location in reliability analysis. This work addresses the issue of prohibitive cost of reliability analysis using Monte Carlo sampling for expensive-to-evaluate high-fidelity models by using cheaper-to-evaluate approximations of the high-fidelity model. The method builds on the Efficient Global Reliability Analysis (EGRA) method, which is a surrogate-based method that uses adaptive sampling for refining Gaussian process surrogates for failure boundary location using a single-fidelity model. Our method introduces a two-stage adaptive sampling criterion that uses a multifidelity Gaussian process surrogate to leverage multiple information sources with different fidelities. The method combines expected feasibility criterion from EGRA with one-step lookahead information gain to refine the surrogate around the failure boundary. The computational savings from mfEGRA depends on the discrepancy between the different models, and the relative cost of evaluating the different models as compared to the high-fidelity model. We show that accurate estimation of reliability using mfEGRA leads to computational savings of $\sim$46% for an analytic multimodal test problem and 24% for a three-dimensional acoustic horn problem, when compared to single-fidelity EGRA. We also show the effect of using a priori drawn Monte Carlo samples in the implementation for the acoustic horn problem, where mfEGRA leads to computational savings of 45% for the three-dimensional case and 48% for a rarer event four-dimensional case as compared to single-fidelity EGRA

Treatment of complex interfaces for Maxwell's equations with continuous coefficients using the correction function method

We propose a high-order FDTD scheme based on the correction function method (CFM) to treat interfaces with complex geometry without increasing the complexity of the numerical approach for constant coefficients. Correction functions are modeled by a system of PDEs based on Maxwell's equations with interface conditions. To be able to compute approximations of correction functions, a functional that is a square measure of the error associated with the correction functions' system of PDEs is minimized in a divergence-free discrete functional space. Afterward, approximations of correction functions are used to correct a FDTD scheme in the vicinity of an interface where it is needed. We perform a perturbation analysis on the correction functions' system of PDEs. The discrete divergence constraint and the consistency of resulting schemes are studied. Numerical experiments are performed for problems with different geometries of the interface. A second-order convergence is obtained for a second-order FDTD scheme corrected using the CFM. High-order convergence is obtained with a corrected fourth-order FDTD scheme. The discontinuities within solutions are accurately captured without spurious oscillations.Comment: 29 pages, 12 figures, modification of Acknowledgment

A necrópole romana do Casal do Rebolo (Almargem do Bispo, Sintra)

Tese de mestrado, Arqueologia, Universidade de Lisboa, Faculdade de Letras, 2012Trabalhos de prospecção realizados na década de 1980 identificaram no Casal do Rebolo (Sintra) materiais que indicavam a ocupação do local durante a Idade do Ferro e época romana. Recentemente, trabalhos de escavação desenvolvidos no local permitiram identificar uma necrópole e algumas estruturas que documentam a existência de uma villa naquele sítio, encontrando-se as duas áreas separadas por uma linha de água. Neste trabalho são apresentados os contextos funerários, como parte principal deste estudo, mas também as principais evidências da parte habitacional. A necrópole foi utilizada provavelmente desde o fim do século II d.C. até ao século IV d.C., coincidindo com uma fase de transição de rituais, com progressivo abandono da incineração e adopção da inumação como ritual principal, situação que está documentado neste conjunto de enterramentos. É também discutida a funcionalidade das estruturas hidráulicas documentadas na necrópole e a sua eventual relação com os contextos funerários. As estruturas e materiais identificados na parte habitacional, designadamente um hipocaustum, a presença de centenas de tesselae fora do seu contexto original, de terra sigillata e de alguns elementos arquitectónicos, apontam para que correspondam à pars urbana da villa, não sendo de excluir a localização das termas naquele local. O estudo de materiais revelou que a villa teve uma ocupação praticamente contemporânea da necrópole.Abstract: Prospecting work carried out in the 1980’s identified materials in Casal do Rebolo (Sintra), which bear witness to the occupation of the site during the Iron Age and the Roman times. The excavation work undertaken in the past few years on that site uncovered a necropolis and some structures that document the existence of a villa on that site. This paper lays down the funerary contexts as main part of this study, but also the main evidence of the habitation part. The necropolis was probably used from the end of the 2nd century AD to the 4th century AD, coinciding with a ritual transition phase, with a gradual abandonment of cremation and the adoption of inhumation as the main ritual, as documented in this set of burials. The functionality of the hydraulic structure documented in the necropolis is also discussed, as well as its eventual connection with the funerary contexts. The structures and materials identified in the habitation part, namely a hipocaustum, the presence of hundreds of tesselae outside their original context, terra sigillata and some architectural elements suggest that they correspond to the pars urbana of the villa; in addition to this, we also have to consider the location of thermal baths on that site. The study of the materials revealed that the occupation of the villa was practically contemporary with the necropolis

Ressonância ferromagnética de filmes finos de ferrite de zinco

Mestrado em Engenharia FísicaEste projeto teve como objetivo o estudo de filmes finos de ZnFe2O4 (ZFO) crescidos por deposição por laser pulsado (PLD). As ferrites são muito sensíveis às condições de crescimento, e, por isso, é que apresentam uma variedade de propriedades em função do modo como são crescidas (microestrutura). Filmes finos de ferrites têm motivado vários estudos teóricos e experimentais devido a novas propriedades elétricas, óticas e magnéticas, bem como a aplicações destes materiais à microeletrónica, magneto-ótica e spintrónica. As amostras foram crescidas por (PLD) sob específicas condições (pressão parcial de oxigénio, aquecimento, temperatura dos substratos), em substratos de r-safira, de SrTiO3 (001),e de SrRuO3/SrTiO3(001). Medidas de ressonância ferromagnética (FMR) foram usadas para o estudo do comportamento magnético de várias séries de filmes finos de ZFO com diferentes orientações das amostras relativamente ao campo magnético externo. Dados da magnetização estática num SQUID, dados de difração de raios-X (DRX) e de energia de dispersão de raios-x (EDX) obtidos nas mesmas amostras foram analisadas em conjunto com os espectros de FMR com o intuito de atingir uma interpretação de confiança. As medidas de FMR foram realizadas no intervalo de temperaturas entre 5 K e 420K a uma frequência de aproximadamente 9.4 GHz (banda X de micro-ondas) em campos magnéticos até aos 1.5T, num espectrómetro ESP 300E da Bruker equipado com crióstatos de fluxo de azoto e hélio. Os espectros foram obtidos para rotações do campo magnético aplicado dentro do plano e fora do plano dos filmes. A análise das dependências angulares dos espectros de FMR foi efetuada no âmbito do formalismo de Smith-Beljers. Praticamente todos os filmes exibiram a razão quase estequiométrica Zn/Fe e a presença de ordem magnética, mesmo que a fase de ferrite de zinco com a estrutura de espinela não foi detetada nas amostras crescidas a temperaturas de substrato inferiores a Tsub = 1000K. Também foi constatado que a qualidade cristalina depende fortemente da pressão parcial de oxigénio durante a deposição dos filmes. Filmes de ZnxFe3−xO4 monofásicas e com textura pronunciada foram obtidos em substratos de SrTiO3 para PO2 = 210–3 mbar e Tsub = 1000 K. Medições de FMR revelaram a existência, nestes filmes, de anisotropia cúbica. Os valores de magnetização efetiva e parâmetro de anisotropia cúbica (4πMeff ≈ 3.0kOe e K1c = –1.5104 erg/cm3) foram obtidos através de uma análise detalhada dos espectros de FMR. Mesmo que nenhuma estrutura cristalina pudesse ser atribuída aos filmes crescidos a Tsub < 1000 K, ondas de spin bem resolvidas foram detetadas num destes a temperaturas criogénicas. O respetivo parâmetro de rigidez (~810–8 erg/cm) é cinco vezes menor do que o valor previamente relatado na literatura para filmes de ZFO. A largura de linha é em todos os casos bastante grande, indicando heterogeneidades internas. Na maioria das amostras, ressonâncias adicionais foram observadas que podem resultar de: modos superficiais, ondas de spin e ou da presença de fases magnéticas diferentes.The object of this study have been ZnFe2O4 (ZFO) thin films grown by pulsed laser deposition (PLD). The ferrites are extremely sensible to the growth conditions, so that they represent a variety of properties as a function of the growth conditions (microstructure). Ferrite thin films have motivated a lot of theoretical and experimental studies owing to novel electric, optical and magnetic properties and possible applications in microelectronics, magnetooptics and spintronics. The samples were grown by pulsed laser deposition (PLD) under specific conditions (partial oxygen pressure, heating) on r-sapphire and (001) SrTiO3 substrates, with and without SrRuO3 buffer layers. For the study of the magnetic behavior of various series of ZFO thin films, ferromagnetic resonance (FMR) measurements as a function of the temperature and sample orientation with respect to the external magnetic field have been performed. Static magnetization data measured in a SQUID magnetometer, energy-dispersive X-ray spectrometry results and x-ray diffraction (XRD) curves obtained on the same samples have been analyzed together with the FMR spectra in order to obtain the most full and reliable interpretation of the results. FMR spectra were measured in the X-band (f ≈ 9.4 GHz) at temperatures from 5 to 420K on a Bruker ESP 300E EPR spectrometer equipped with a helium and a nitrogen continuous flow cryostats. Azimuthal (in-plane) and polar (out-of-plane) angular dependences of the FMR spectra for sample rotation in external magnetic field up to 1.5 T have been measured. The analysis of the angular dependences of the spectra have been performed in the framework of the Smith-Beljers formalism. A zinc ferrite spinel phase has been found only in the samples grown at Tsub = 1000K. Nevertheless, almost all samples exhibited a stoichiometric Zn/Fe ratio and magnetic (non-paramagnetic) ordering, even when the spinel phase was absent in film. The quality of the zinc ferrite films was found to be strongly dependent on the oxygen partial pressure during the deposition. Increasing of the oxygen pressure during the deposition efficiently removes second phases like iron and zinc oxides from the film. Monophase, highly textured zinc ferrite films have been grown on (001) SrTiO3 substrates at PO2 = 210–3 mbar and Tsub = 1000 K. FMR conducted on these films has revealed a fourfold cubic magnetic anisotropy with 4πMeff ≈ 3.0 kOe e K1c = –1.5104 erg/cm3. Though no crystalline structure could be found in the samples grown at Tsub < 1000 K, well-resolved spin wave spectra have been detected in one of them at cryogenic temperatures. The respective stiffness parameter (~810–8 erg/cm) is at least five times smaller than the value reported formerly in zinc-ferrite films. The FMR line width is in all cases pretty large, indicating internal heterogeneities in the films. In most of the samples, additional resonances were detected, possibly due to surface modes, spin waves and the presence of different magnetic phases

Equity research - VWS Wind Systems A/S

Mestrado Bolonha em FinançasEste relatório contém uma avaliação da Vestas Wind Systems A/S, preparado como Projeto Final de Mestrado em Finanças do ISEG. Este Relatório de Avaliação segue o formato recomendado pelo CFA Institute (Pinto, Henry, Robinson, and Stowe, 2010). O presente estudo foi organizado considerando informação publicamente disponível a 26 de outubro de 2018, de acordo com diversas fontes, entre as quais relatórios de contas anuais, Thomson Reuters, e Bloomberg L.P. Deste modo, quaisquer eventualidades ocorridas após esta data não são consideradas no relatório. O preço-alvo foi alcançado com recurso ao método do Valor Económico Acrescentado, com complemento ao método de avaliação relativa dos múltiplos. Com um preço-alvo obtido de €65.00 e um potencial de valorização de 18.26% face ao atual de €54.96, a nossa recomendação final para a Vestas Wind Systems é de "Compra", e a nossa avaliação de risco é de médio risco para VWS.This report is a valuation of Vestas Wind Systems A/S, prepared as a Masters' of Finance Final Work Project at ISEG. This Equity Research follows the recommended format by the CFA Institute (Pinto, Henry, Robinson, and Stowe, 2010). This study was conducted considering publicly available data on October 26th, 2018 accordingly to diverse sources, such as company reports, Thomson Reuters, and Bloomberg L.P.. Hence, any events or circumstances occurring after this date were not taken into account in this report. The target price was achieved based on the Economic Value Added Method, complemented with the relative valuation approach of Comparables. With a price target of €65.00 for YE18, representing an upside potential of 18.26% from the current price of €54.96, our final recommendation for Vestas Wind Systems A/S stands for "Buy", and our risk assessment estimates a medium risk for VWS.info:eu-repo/semantics/publishedVersio

Case study: the power of Hoshin Kanri

The purpose of this Work Project is to provide insight into one of the pillars of Lean through a real case-study on one of Logoplaste’s factories in Kansas City, USA. Some of the topics that will be covered are Lean management, Lean accounting, and Hoshin Kanri tools, which address problems faced by companies in the manufacturing sector. This paper presents how Hoshin Kanri affected in a positive way Logoplaste’s profit and serves as an example to organizations that wish to adopt this strategic planning methodology

North and South, the Journey and the Return.

Asplund não foi o último nem foi o primeiro arquiteto nórdico a viajar para Sul. Na realidade, os territórios e as diferentes culturas que aconteceram no Mediterrâneo - seja na península de Itália, ou da Grécia, passando pelo norte de África -, esse Sul com mais de mil anos de história, foi o “destino” para grande parte dos homens (e mulheres) de cultura, arquitetos ou não, do Norte e do Centro da Europa. Esta viagem, conhecida como a Grand Tour, era vista, desde finais do século XVIII, como um tempo único de passagem, entre o tempo de formação e o tempo da vida que se lhe seguirá. Era o momento de passar da escolástica e da condição restrita de jovem aprendiz e estudante, para entender que só “ir” e ver o mundo com alguma maturidade seria o caminho de perceber o outro, o significado da sua Cultura, dos seus lugares, ou dos seus costumes, para então chegar à condição de “cidadão do mundo”.Asplund was neither the last nor the first Nordic architect to travel to the South. Indeed, the territories and the different cultures that have existed in the Mediterranean - whether in the Italian peninsula or in Greece, including North Africa, that South with over a thousand years of history, was the "destination" for most men (and women) of culture, architects or not, from Northern and Central Europe. This trip, known as the Grand Tour, was perceived, from the end of the eighteenth century, as a unique time of passage between the education period and the period of life that would ensue. It was the time to move from scholasticism and the restricted condition of being a young apprentice and student and to realize that "moving" and seeing the world with some maturity would be paramount to perceive the other, the meaning of his Culture, places and customs, and then reach the status of "citizen of the world"