Eskom provides 98% of South Africa’s ever increasing electricity demand. The mining sector is a vital contributor to the economy, but also consumes vast amounts of electricity. This sector is responsible for almost 15% of the country’s electricity usage. Mines heavily depend on the supply of cold water and air. Refrigeration systems are therefore constantly operational and can account for 25% of a mine’s electricity costs. The need therefore exists to investigate possible energy savings initiatives. Refrigeration systems are typically used to lower the temperature of water and air. Bulk Air Coolers (BACs) are used to produce cold air. The aim of this study is to investigate possible electricity cost savings in a mine refrigeration system. This can be achieved by enabling equipment to dynamically adapt to changes in their environment. Electricity usage reduction has the greatest financial impact if it occurs during Eskom peak periods. Time-dependent schedules of operation are therefore used to achieve this objective. Due to the lack of such a controller in the mining industry, the focus of this study is a BAC control system. A BAC controller would be able to follow guidelines that could lead to electricity cost savings. It was therefore developed and incorporated in the Real-time Energy Management System (REMS). The BAC controller combines various inputs and constraints to determine the output. An electricity usage reduction during the Eskom evening peak period was consequently achieved. The BAC controller was implemented on three sites. Electrical energy usage during the evening peak period was reduced via the load shifting method. This aids Eskom in their effort to reduce the peak period demand. Air temperature and dam levels were closely monitored during the peak period. If any preset condition was violated, the load shifting was abandoned for that day. It was shown that a total power reduction of 7 MW is possible between the three sites. The electricity savings occurred in the evening peak period. A calculation was made to determine the possible annual savings by using the achieved daily cost savings. The winter months were not included in the calculation. An annual cost saving of R1 166 694.41 is therefore possible without having to reduce output quantities. / MIng(Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

A learning task with thousands of training examples in Support Vector Machine (SVM) demands large amounts of memory and time requirements. SVMlight by Dr. Thorsten Joachims has been implemented in C using a fast optimizing algorithm for handling thousands of such support vectors. SVMlight solves the problem of classification, pattern recognition, regression and learning ranking function. The C code also provides methods for XiAlpha estimation of error rate and precision. Implementing these two methods leads to generalized performance of Support Vector Machine even for computation intensive text classification functions. SVMlight code allows users to define their own kernel functions. The SVMlight software employs an efficient algorithm and minimizes the cost, but it still takes considerable amount of time for computing thousands of support vectors and training examples. This time can be still reduced by parallelizing the code. In our work we refined the SVMlight code by removing unnecessary iterations and rewriting it as cost efficient. Then we parallelized the code individually using two different types, OpenMP and POSIX Threads shared memory parallelism. The code is parallelized for these two methods on Intel’s C compiler for Linux 7.1 using hyper threading technology. The parallelized code is tested for protein structure prediction. Different types of Protein Sequences are tested on these methods by varying the number of training examples and support vectors. The time consumption and speedup are calculated for both OpenMP and Pthreads. Implementation of OpenMP and Pthreads together showed good increase in speedup.

In many algorithms for Orthogonal Frequency Division Multiplexing (OFDM) systems, the channel estimation is one of the most essential factors. In wireless environment, channel is change very fast, and the channel has multipath effect, the channel length is obtained by channel estimation. In this paper, we estimation the channel length and the SNR by virtual carriers (VC) and Singular value decomposition, when channel estimator known the information for channel length, then calculate complicated can be reduced. Besides, we proposed the estimated method at carriers frequency offset effect. Noise variance (or noise power) can improve performance of channel estimator, e.g. MMSE channel estimator, turbo code or power allocation. In this paper, we were estimate noise variance by using the blind method of property of orthogonality of matrix, which is differed from the traditional method of Pilots.

Submitted by LEDA RIBEIRO NOGUEIRA null (led_nogueira@hotmail.com) on 2016-10-27T18:24:11Z No. of bitstreams: 1 VERSÃO FINAL PARA O REPOSITÓRIO-DISSERTAÇÃO DE MESTRADO.pdf: 2487059 bytes, checksum: 2da98711e0c738f9472b37e4b310b4b0 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-03T18:05:27Z (GMT) No. of bitstreams: 1 nogueira_lr_me_soro.pdf: 2172157 bytes, checksum: a7db0217b115ba75e70b9535773ceedb (MD5) / Made available in DSpace on 2016-11-03T18:05:27Z (GMT). No. of bitstreams: 1 nogueira_lr_me_soro.pdf: 2172157 bytes, checksum: a7db0217b115ba75e70b9535773ceedb (MD5) Previous issue date: 2016-09-02 / Os estudos dos efeitos de agentes tóxicos nos organismos aquáticos são necessários para o estabelecimento de concentrações seguras de exposição, destacando-se o uso para a proteção da vida aquática. Nesse contexto, o pesticida emergente chlorantraniliprole tem sido utilizado desde 2007 em algumas culturas como cana-de-açúcar, arroz, milho, maçã, uva, dentre outras. Poucas informações ecotoxicológicas sobre este pesticida são relatadas na literatura considerando-se sua atuação nos ambientes de águas doces. Diante do exposto, o objetivo deste trabalho foi avaliar os aspectos ecotoxicológicos deste inseticida sobre o organismo-teste Ceriodaphnia dubia por meio de testes de toxicidade aguda, buscando-se obter o valor médio de CE50 (48h) (Concentração que causa efeito em 50% da população em 48h, por meio da análise da imobilidade ou mortalidade) calculado por meio do Software ICPIN e do método de Interpolação Linear, e por meio de testes de toxicidade crônica, buscando-se adquirir os valores de CENO (maior concentração de efeito não observado na reprodução), CEO (menor concentração de efeito observado sobre os aspectos reprodutivos) e VC (valor crônico – média geométrica entre CENO e CEO). Os valores de CENO e CEO foram obtidos utilizando-se o Software BioStat 5.3 e o método de Kruskal-Wallis, a fim de se comparar a significância da redução no número de neonatos em relação ao grupo controle. As soluções-teste foram preparadas, a partir do padrão puro de chlorantraniliprole ( Sigma-Aldrich, 99% de pureza) e solubilizado em acetona. O resultado para a toxicidade aguda com C. dubia foi de 2,9±1,11 µg/L. Os testes de toxicidade crônica revelaram CENO de 0,61±0,33 µg/L, CEO de 0,91±0,49 µg/L e VC foi de 0,74 µg/L. Considerando-se a proteção da vida aquática, recomenda-se, com base na presente pesquisa, uma concentração de 0,74 µg/L do princípio ativo do pesticida chlorantraniliprole, como limite seguro. / Studies of the effects of toxic agents on aquatic organisms are needed to establish safe levels of exposure, especially the use for the protection of aquatic life. In this context, chlorantraniliprole emerging pesticide has been used since 2007 in some crops such as sugarcane, rice, corn, apples, grapes and others. Few ecotoxicological information is reported in the literature considering its performance in freshwater environments. Given the above, the objective of this study was to evaluate the ecotoxicological aspects of this insecticide on the Ceriodaphnia dubia test organism through acute toxicity tests, seeking to obtain the average value of EC50 (48h) (concentration causing effect by 50% population in 48 hours, through the analysis of inhibition of swimming or mortality), and through chronic toxicity tests, searching for acquiring the NOEC values (greater concentration effect not observed in the reproduction ), LOEC (lowest observed effect concentration on the reproductive aspects) and CV (chronic value - geometric mean of NOEC and LOEC). The NOEC and LOEC values were performed using the BioStat 5.3 software and the statistical analysis Kruskal-Wallis test to compare the significance of the reduction in the number of newborns in the control group. The test solutions were prepared from the neat standard chlorantraniliprole (Sigma-Aldrich, 99% purity) and solubilized in acetone. The results for acute toxicity C. dubia were 2.9 ± 1.11 µg / L-1. The chronic toxicity tests revealed NOEC of 0.61 ± 0.33 µg / L-1, LOEC of 0.91 ± 0.49 µg / L-1 and CV was 0.74 µg / L-1. Considering and protection of aquatic life, it is recommended based on this study, a concentration of 0.74 µg / L-1 of the active ingredient of the pesticide chlorantraniliprole as safe limit.

No description available.

The state of the art in machine learning of Boolean functions is to learn a hypothesis h, which is similar to a target hypothesis f, using a training sample of size N and a family of a priori models in a given hypothesis set H, such that h must belong to some model in this family. An important characteristic in learning is that h should also predict outcome values of f for previously unseen data, so the learning algorithm should minimize the generalization error which is the discrepancy measure between outcome values of f and h. The method proposed in this thesis learns family of models compatible with training samples of size N. Taking into account that generalizations are performed through equivalence classes in the Boolean function domain, the search space for finding the correct model is the projection of H in all possible partitions of the domain. This projection can be seen as a model lattice which is anti-isomorphic to the partition lattice and also has the property that for every chain in the lattice there exists a relation order given by the VC dimension of the models. Hence, we propose a model selector that uses the model lattice for selecting the best model with VC dimension compatible to a training sample of size N, which is closely related to the classical sample complexity theorem. Moreover, this model selector generalizes a set of learning methods in the literature (i.e, it unifies methods such as: the feature selection problem, multiresolution representation and decision tree representation) using models generated from a subset of partitions of the partition space. Furthermore, considering as measure associated to the models the estimated error of the learned hypothesis, the chains in the lattice present the so-called U-curve phenomenon. Therefore, we can use U-curve search algorithms in the model lattice to select the best models and, consequently, the corresponding VC dimension. However, this new generation of learning algorithms requires an increment of computational power. In order to face this problem, we introduce a stochastic U-curve algorithm to work on bigger lattices. Stochastic search algorithms do not guarantee finding optimal solutions, but maximize the mean quality of the solution for a given amount of computational power. The contribution of this thesis advances both the state of the art in machine learning theory and in practical problem solutions in learning. / O estado da arte em aprendizado de funções Booleanas é aprender uma hipótese h, que é similar a uma hipótese objetivo f, a partir de uma amostra de tamanho N e uma família de modelos a priori em um dado conjunto de hipóteses H, tal que h deve pertencer a algum modelo nesta família. Uma característica importante no aprendizado é que h deve também predizer resultados de f para elementos que não aparecem no conjunto de treinamento, então o algoritmo de aprendizado deve minimizar o erro de generalização, o qual mede a discrepância entre os resultados de f e h. O método proposto nesta tese aprende uma família de modelos compatíveis com um conjunto de treinamento de tamanho N. Tomando em consideração que as generalizações são realizadas através de classes de equivalência no domínio da função Booleana, o espaço de busca para encontrar um modelo apropriado é a projeção de H em todas as possíveis partições do domínio. Esta projeção pode ser vista como um reticulado de modelos que é anti-isomórfica ao reticulado de partições e também tem a propriedade que para cada cadeia no reticulado existe uma relação de ordem dada pela dimensão VC dos modelos. Portanto, propomos um seletor de modelos que usa o reticulado de modelos para selecionar o melhor modelo com dimensão VC compatível ao conjunto de treinamento de tamanho N, o qual é intimamente relacionado ao teorema clássico de complexidade da amostra. Além disso, este seletor de modelos generaliza um conjunto de métodos de aprendizado na literatura (i.e, ele unifica métodos tais como: o problema de seleção de características, a representação multiresolução e a representação por árvores de decisão) usando modelos gerados por um subconjunto de partições do espaço de partições. Ademais, considerando como medida associada aos modelos o erro de estimação da hipótese aprendida, as cadeias no reticulado apresentam o fenômeno chamado U-curve. Portanto, podemos usar algoritmos de busca $U$-curve no reticulado de modelos para selecionar os melhores modelos, consequentemente, a correspondente dimensão VC. No entanto, esta nova geração de algoritmos de aprendizado requerem um incremento de poder computacional. Para enfrentar este problema, introduzimos o algoritmo Stochastic $U$-curve para trabalhar em reticulados maiores. Algoritmos de busca estocásticos não garantem encontrar soluções ótimas, mas maximizam a qualidade média das soluções para uma determinada quantidade de poder computacional. A contribuição desta tese avança ambos o estado da arte na teoria de aprendizado de máquina e soluções a problemas práticos em aprendizado.

Dans cette thèse, nous étudions des problèmes de transversaux d'un point de vue tant algorithmique que combinatoire. Etant donné un hypergraphe, un transversal est un ensemble de sommets qui touche toutes les hyperarêtes. Un packing est un ensemble d'hyperarêtes deux à deux disjointes. Alors que la taille minimale d'un transversal est au moins égale à la taille maximale d'un packing on ne peut pas dans le cas général borner la taille minimale d'un transversal par une fonction du packing maximal. Dans un premier temps, un état de l'art rappelle les différentes conditions qui assurent l'existence de bornes supérieures sur la taille des transversaux, en particulier en fonction de la taille d'un packing. La plupart d'entre elles sont valables lorsque la VC-dimension de Vapnik-Chervonenkis de l'hypergraphe, est bornée. L'originalité de la thèse consiste à utiliser ces outils d'hypergraphes pour obtenir des résultats sur des problèmes de graphes. Nous prouvons notamment une conjecture de coloration de Scott dans le cas des graphes sans-triangle maximaux; ensuite, nous généralisons un résultat de Chepoi, Estellon et Vaxès traitant de domination à grande distance; enfin nous nous attaquons à une conjecture de Yannakakis sur la séparation des cliques et des stables d'un graphe.Dans un second temps, nous étudions les transversaux d'un point de vue algorithmique. On se concentre plus particulièrement sur les problèmes de séparation de graphe où on cherche des transversaux à un ensemble de chemin. En combinant des outils de connexité, les séparateurs importants et le théorème de Dilworth, nous obtenons un algorithme FPT pour le problème Multicut paramétré par la taille de la solution. / In this manuscript we study hitting sets both from a combinatorial and from an algorithmic point of view. A hitting set is a subset of vertices of a hypergraph which intersects all the hyperedges. A packing is a subset of pairwise disjoint hyperedges. In the general case, there is no function linking the minimum size of a hitting set and a maximum size of a packing.The first part of this thesis is devoted to present upper bounds on the size of hitting sets, in particular this upper bounds are expressed in the size of the maximum packing. Most of them are satisfied when the dimension of Vapnik-Chervonenkis of the hypergraph is bounded. The originality of this thesis consists in using these hypergraph tools in order to obtain several results on graph problems. First we prove that a conjecture of Scott holds for maximal triangle-free graphs. Then we generalize a result of Chepoi, Estellon and Vaxès on dominating sets at large distance. We finally study a conjecture of Yannakakis and prove that it holds for several graph subclasses using VC-dimension.The second part of this thesis explores algorithmic aspects of hitting sets. More precisely we focus on parameterized complexity of graph separation problems where we are looking for hitting sets of a set of paths. Combining connectivity tools, important separator technique and Dilworth's theorem, we design an FPT algorithm for the Multicut problem parameterized by the size of the solution.

O sucesso alcançado pela indústria de Private Equity e Venture Capital (PE/VC) no fomento ao empreendedorismo e na dinamização do setor empresarial norte-americano encorajou diversos países a importar este modelo vencedor de intermediação financeira. Este trabalho busca analisar como as empresas de PE/VC realizam suas avaliações de potenciais investimentos e tomam suas decisões de investimento através da identificação junto à literatura das principais variáveis utilizadas e a verificação de como as mesmas se manifestam nas empresas pesquisadas. Na pesquisa sobre o perfil da indústria de PE/VC mineira podemos citar três fatores que nos permitem prever grande crescimento e desenvolvimento da mesma: i) existência de uma rede que contempla todos os ciclos do processo de investimento; ii) a grande presença de empresas atuando nos estágios iniciais do ciclo de investimento; e iii) boa margem de sucesso nos investimentos. Como principal conclusão da pesquisa do como as empresas pesquisadas avaliam possíveis investimentos, podemos citar o fato das empresas pesquisadas focarem muito mais os fatores intangíveis como a equipe, a estratégia e o mercado potencial do que os fatores tangíveis como os aspectos financeiros, tamanho de mercado já existente e planos de negócios. / The outstanding success achieved by Private Equity and Venture Capital (PE/VC) in fostering the U.S. enterprising sector has encouraged several countries to import this winner financial model. The objective of this work is to analyze how the PE/VC Companies make the analysis of the potential investment in PE/VC and take the investment decision through the identification in the literature of the most important variables and the verification of how it works in the analyzed organizations. In the study of the profile of the industry of PE/VC from Minas Gerais, Brazil, we can identify three factors that allows to foresee a great growth and development of this industry: i) existence of a net that contemplates all the cycles of the investment process; ii) the great presence of companies acting in the initial periods of training of the investment cycle; and iii) good percentage of success in the investments. As main conclusion of the study of the evaluation variables we can quote the fact of the searched organizations focus much more in the intangible factors as the team, strategy and potential market than in the tangible ones as the financial aspects, the size of the actual market and the business plans.

O sucesso alcançado pela indústria de Private Equity e Venture Capital (PE/VC) no fomento ao empreendedorismo e na dinamização do setor empresarial norte-americano encorajou diversos países a importar este modelo vencedor de intermediação financeira. Este trabalho busca analisar como as empresas de PE/VC realizam suas avaliações de potenciais investimentos e tomam suas decisões de investimento através da identificação junto à literatura das principais variáveis utilizadas e a verificação de como as mesmas se manifestam nas empresas pesquisadas. Na pesquisa sobre o perfil da indústria de PE/VC mineira podemos citar três fatores que nos permitem prever grande crescimento e desenvolvimento da mesma: i) existência de uma rede que contempla todos os ciclos do processo de investimento; ii) a grande presença de empresas atuando nos estágios iniciais do ciclo de investimento; e iii) boa margem de sucesso nos investimentos. Como principal conclusão da pesquisa do como as empresas pesquisadas avaliam possíveis investimentos, podemos citar o fato das empresas pesquisadas focarem muito mais os fatores intangíveis como a equipe, a estratégia e o mercado potencial do que os fatores tangíveis como os aspectos financeiros, tamanho de mercado já existente e planos de negócios. / The outstanding success achieved by Private Equity and Venture Capital (PE/VC) in fostering the U.S. enterprising sector has encouraged several countries to import this winner financial model. The objective of this work is to analyze how the PE/VC Companies make the analysis of the potential investment in PE/VC and take the investment decision through the identification in the literature of the most important variables and the verification of how it works in the analyzed organizations. In the study of the profile of the industry of PE/VC from Minas Gerais, Brazil, we can identify three factors that allows to foresee a great growth and development of this industry: i) existence of a net that contemplates all the cycles of the investment process; ii) the great presence of companies acting in the initial periods of training of the investment cycle; and iii) good percentage of success in the investments. As main conclusion of the study of the evaluation variables we can quote the fact of the searched organizations focus much more in the intangible factors as the team, strategy and potential market than in the tangible ones as the financial aspects, the size of the actual market and the business plans.

O sucesso alcançado pela indústria de Private Equity e Venture Capital (PE/VC) no fomento ao empreendedorismo e na dinamização do setor empresarial norte-americano encorajou diversos países a importar este modelo vencedor de intermediação financeira. Este trabalho busca analisar como as empresas de PE/VC realizam suas avaliações de potenciais investimentos e tomam suas decisões de investimento através da identificação junto à literatura das principais variáveis utilizadas e a verificação de como as mesmas se manifestam nas empresas pesquisadas. Na pesquisa sobre o perfil da indústria de PE/VC mineira podemos citar três fatores que nos permitem prever grande crescimento e desenvolvimento da mesma: i) existência de uma rede que contempla todos os ciclos do processo de investimento; ii) a grande presença de empresas atuando nos estágios iniciais do ciclo de investimento; e iii) boa margem de sucesso nos investimentos. Como principal conclusão da pesquisa do como as empresas pesquisadas avaliam possíveis investimentos, podemos citar o fato das empresas pesquisadas focarem muito mais os fatores intangíveis como a equipe, a estratégia e o mercado potencial do que os fatores tangíveis como os aspectos financeiros, tamanho de mercado já existente e planos de negócios. / The outstanding success achieved by Private Equity and Venture Capital (PE/VC) in fostering the U.S. enterprising sector has encouraged several countries to import this winner financial model. The objective of this work is to analyze how the PE/VC Companies make the analysis of the potential investment in PE/VC and take the investment decision through the identification in the literature of the most important variables and the verification of how it works in the analyzed organizations. In the study of the profile of the industry of PE/VC from Minas Gerais, Brazil, we can identify three factors that allows to foresee a great growth and development of this industry: i) existence of a net that contemplates all the cycles of the investment process; ii) the great presence of companies acting in the initial periods of training of the investment cycle; and iii) good percentage of success in the investments. As main conclusion of the study of the evaluation variables we can quote the fact of the searched organizations focus much more in the intangible factors as the team, strategy and potential market than in the tangible ones as the financial aspects, the size of the actual market and the business plans.