Waveshapes of continuing currents and properties of M-components in natural positive cloud-to-ground lightning

This work analyses the waveshapes of continuing currents and parameters of M-components in positive cloud-to-ground (CG) flashes through high-speed GPS synchronized videos. The dataset is composed of only long continuing currents (with duration longer than 40 ms) and was selected from more than 800 flashes recorded in Sao Jose dos Campos (45.864 degrees W, 23.215 degrees S) and Uruguaiana (29.806 degrees W, 57.005 degrees S) in Southeast and South of Brazil, respectively, during 2003 to 2007 summers. The videos are compared with data obtained by the Brazilian Lightning Location System (BrasilDAT) in order to determine the polarity of each flash and select only positive cases. There are only two studies of waveshapes of continuing currents in the literature. One is based on direct current measurements of triggered lightning, in which four different types of waveshapes were observed; and the other is based on measurements of luminosity variations in high-speed videos of CG negative lightning, in which besides the four types above mentioned two additional types were observed. The present work is an extension of the latter, using the same method but now applied to obtain the waveshapes of positive CG lightning. As far as the authors know, this is the first report on M-components in positive continuing currents. We also have used the luminosity-versus-time graphs to observe their occurrence and measure some parameters (duration, elapsed time and time between two successive M-components), whose statistics are presented and compared in detail to the data for negative flashes. We have plotted a histogram of the M-components elapsed time over the total duration of the continuing current for positive flashes, which presented an exponential decay (correlation coefficient: 0.83), similar to what has been observed for negative flashes. (C) 2008 Elsevier B.V. All rights reserved.

Desenvolvimento e teste de um modelo estatístico de identificação das proporções de água produzida em zonas de produção de um campo maduro de petróleo

This study investigates the chemical species produced water from the reservoir areas of oil production in the field of Monte Alegre (onshore production) with a proposal of developing a model applied to the identification of the water produced in different zones or groups of zones.Starting from the concentrations of anions and cátions from water produced as input parameters in Linear Discriminate Analysis, it was possible to estimate and compare the model predictions respecting the particularities of their methods in order to ascertain which one would be most appropriate. The methods Resubstitution, Holdout Method and Lachenbruch were used for adjustment and general evaluation of the built models. Of the estimated models for Wells producing water for a single production area, the most suitable method was the "Holdout Method and had a hit rate of 90%. Discriminant functions (CV1, CV2 and CV3) estimated in this model were used to modeling new functions for samples ofartificial mixtures of produced water (producedin our laboratory) and samples of mixtures actualproduced water (water collected inwellsproducingmore thanonezone).The experiment with these mixtures was carried out according to a schedule experimental mixtures simplex type-centroid also was simulated in which the presence of water from steam injectionin these tanks fora part of amostras. Using graphs of two and three dimensions was possible to estimate the proportion of water in the production area

Agraphs: definição, implementação e suas ferramentas

Programs manipulate information. However, information is abstract in nature and needs to be represented, usually by data structures, making it possible to be manipulated. This work presents the AGraphs, a representation and exchange format of the data that uses typed directed graphs with a simulation of hyperedges and hierarchical graphs. Associated to the AGraphs format there is a manipulation library with a simple programming interface, tailored to the language being represented. The AGraphs format in ad-hoc manner was used as representation format in tools developed at UFRN, and, to make it more usable in other tools, an accurate description and the development of support tools was necessary. These accurate description and tools have been developed and are described in this work. This work compares the AGraphs format with other representation and exchange formats (e.g ATerms, GDL, GraphML, GraX, GXL and XML). The main objective this comparison is to capture important characteristics and where the AGraphs concepts can still evolve

Detecção e recuperação de falhas para a máquina de redução de grafos PEWS-AM

Web services are software units that allow access to one or more resources, supporting the deployment of business processes in the Web. They use well-defined interfaces, using web standard protocols, making possible the communication between entities implemented on different platforms. Due to these features, Web services can be integrated as services compositions to form more robust loose coupling applications. Web services are subject to failures, unwanted situations that may compromise the business process partially or completely. Failures can occur both in the design of compositions as in the execution of compositions. As a result, it is essential to create mechanisms to make the implementation of service compositions more robust and to treat failures. Specifically, we propose the support for fault recovery in service compositions described in PEWS language and executed on PEWS-AM, an graph reduction machine. To support recovery failure on PEWS-AM, we extend the PEWS language specification and adapted the rules of translation and reduction of graphs for this machine. These contributions were made both in the model of abstract machine as at the implementation level

O problema do Hiker Dice em tabuleiro compacto: um estudo algorítmico

The Hiker Dice was a game recently proposed in a software designed by Mara Kuzmich and Leonardo Goldbarg. In the game a dice is responsible for building a trail on an n x m board. As the dice waits upon a cell on the board, it prints the side that touches the surface. The game shows the Hamiltonian Path Problem Simple Maximum Hiker Dice (Hidi-CHS) in trays Compact Nth , this problem is then characterized by looking for a Hamiltonian Path that maximize the sum of marked sides on the board. The research now related, models the problem through Graphs, and proposes two classes of solution algorithms. The first class, belonging to the exact algorithms, is formed by a backtracking algorithm planed with a return through logical rules and limiting the best found solution. The second class of algorithms is composed by metaheuristics type Evolutionary Computing, Local Ramdomized search and GRASP (Greed Randomized Adaptative Search). Three specific operators for the algorithms were created as follows: restructuring, recombination with two solutions and random greedy constructive.The exact algorithm was teste on 4x4 to 8x8 boards exhausting the possibility of higher computational treatment of cases due to the explosion in processing time. The heuristics algorithms were tested on 5x5 to 14x14 boards. According to the applied methodology for evaluation, the results acheived by the heuristics algorithms suggests a better performance for the GRASP algorithm

Lazer e urbanização: a dinâmica do setor de serviços no litoral de Parnamirim e Nísia Floresta - RN

The research here undertaken analyzes the process of urbanization on the coast of Panamirim - RN and Nísia Floresta - RN, arising from leisure, the main leisure expression was considered the second residence and coastal tourism. The leisure promoted the growth of businesses and public and private services to meet consumer demand in that area, which initially occurred with users of second home, and which also gradually begin to occupy the coastline of these municipalities in 1980 and more recently with the development of tourism in the 1990s until now. To undertake such an analysis, we did the georeferencing about the trade and also public and private services of that coast, characterizing them; evaluated the extent to which services deployed in this area meets the demands of tourists and users of second residence; it was also identified how the centrality of Natal interferes in the expansion of services in these locations. The spatial area of research includes the coastal municipalities of Parnamirim and Nísia Floresta, considering the limits of the census of the Instituto Brasileiro de Geografia e Estatística- IBGE, and about the time frame, it was considered the 1990s to the present day. The methodology consists of: 1. survey and reading of the literature related to the researched topic, serving as the theoretical analysis in the construction of the object studied; 2. collection and organization of secondary data by the IBGE and tourism sectors of the State of Rio Grande do Norte, Natal and main municipalities of the research; 3. Questionnaires and / or interviews with the traders, service providers, tourists, users of second homes, local residents, and government. The analysis of such data collected allowed the preparation of graphs, maps and tables that illustrate the results obtained in the research field, basing so the study. The relevance of the study is shown by the extensive survey data involving agents of the research, including tourists, users of second homes and, above all, the data for the service sector that did not exist in the analyzed area. The study results identified in the area analyzed the emergence of three new centers, arising from the urbanization process from leisure, one of them located in the municipality of Nísia Foresta Beach in Barra de Tabatinga, and two in Parnamirim, more specifically in locality Pium and Beach Pirangi do Norte. It was further observed that, being located in tourist areas, the main feature of these new centers is seasonality

Física estatística aplicada a sistemas sociais através do estudo de redes complexas

In this work a study of social networks based on analysis of family names is presented. A basic approach to the mathematical formalism of graphs is developed and then main theoretical models for complex networks are presented aiming to support the analysis of surnames networks models. These, in turn, are worked so as to be drawn leading quantities, such as aggregation coefficient, minimum average path length and connectivity distribution. Based on these quantities, it can be stated that surnames networks are an example of complex network, showing important features such as preferential attachment and small-world character

Ergodicidade em cadeias de Markov não-homogêneas e cadeias de Markov com transições raras

The central objective of a study Non-Homogeneous Markov Chains is the concept of weak and strong ergodicity. A chain is weak ergodic if the dependence on the initial distribution vanishes with time, and it is strong ergodic if it is weak ergodic and converges in distribution. Most theoretical results on strong ergodicity assume some knowledge of the limit behavior of the stationary distributions. In this work, we collect some general results on weak and strong ergodicity for chains with space enumerable states, and also study the asymptotic behavior of the stationary distributions of a particular type of Markov Chains with finite state space, called Markov Chains with Rare Transitions

O estudo das funções quadráticas e sua relação com o cotidiano

Across the centuries, Mathematics - exact science as it is - has become a determining role in the life of man, which forms to use suprir needs of their daily lives. With this trajectory, is characterized the importance of science as an instrument of recovery not only conteudstica, but also a mathematician to know that leads the apprentice to be a dynamic process of learning ecient, able to find solutions to their real problems. However, it is necessary to understand that mathematical knowledge today requires a new view of those who deal directly with the teaching-learning process, as it is for them - Teachers of Mathematics - desmistificarem the version that mathematics, worked in the classroom, causes difficulties for the understanding of students. On this view, we tried to find this work a methodology that helps students better understand the Quadratic functions and its applications in daily life. Making use of knowledge Ethnomathematics, contextualizing the problems relating to the content and at the same time handling the software GeoGebra, aiming a better view of the behavior of graphs of functions cited

Uma colônia de formigas para o caminho mais curto multiobjetivo

Multi-objective combinatorial optimization problems have peculiar characteristics that require optimization methods to adapt for this context. Since many of these problems are NP-Hard, the use of metaheuristics has grown over the last years. Particularly, many different approaches using Ant Colony Optimization (ACO) have been proposed. In this work, an ACO is proposed for the Multi-objective Shortest Path Problem, and is compared to two other optimizers found in the literature. A set of 18 instances from two distinct types of graphs are used, as well as a specific multiobjective performance assessment methodology. Initial experiments showed that the proposed algorithm is able to generate better approximation sets than the other optimizers for all instances. In the second part of this work, an experimental analysis is conducted, using several different multiobjective ACO proposals recently published and the same instances used in the first part. Results show each type of instance benefits a particular type of instance benefits a particular algorithmic approach. A new metaphor for the development of multiobjective ACOs is, then, proposed. Usually, ants share the same characteristics and only few works address multi-species approaches. This works proposes an approach where multi-species ants compete for food resources. Each specie has its own search strategy and different species do not access pheromone information of each other. As in nature, the successful ant populations are allowed to grow, whereas unsuccessful ones shrink. The approach introduced here shows to be able to inherit the behavior of strategies that are successful for different types of problems. Results of computational experiments are reported and show that the proposed approach is able to produce significantly better approximation sets than other methods

Estudo in vivo e in vitro com e sem termociclagem, da resistência ao cisalhamento de braquetes colados com fonte de luz halógena

OBJETIVO: avaliar a resistência de braquetes metálicos colados em dentes humanos com resina polimerizada com luz halógena por meio de ensaios mecânicos de cisalhamento. METODOLOGIA: para este estudo foram realizados ensaios in vivo com dinamômetro portátil digital e in vitro com máquina de ensaios mecânicos universal com e sem termociclagem, complementado pelo Índice de Adesivo Remanescente (IAR). Braquetes Edgewise Standard (Abzil) foram colados utilizando adesivo Transbond Plus Self Etching Primer (SEP) e Resina Transbond XT. Foram formados 3 grupos com 10 dentes em cada um deles. No GI os braquetes foram colados nos segundos pré-molares dos pacientes. Nos GII e GIII utilizaram-se primeiros pré-molares extraídos por motivos ortodônticos. Os ensaios mecânicos do GI foram realizados 24 horas após a polimerização diretamente na boca dos pacientes com dinamômetro portátil digital. No GII os corpos-de-prova foram armazenados em água destilada e levados à estufa a 37ºC durante 24 horas e, posteriormente, submetidos à termociclagem, com 1000 ciclos a 5 e 55ºC. No GIII os corpos-de-prova foram armazenados em água destilada em temperatura ambiente por 24 horas e posteriormente submetidos aos ensaios mecânicos. RESULTADOS: os valores médios da resistência ao cisalhamento em Megapascal foram de: GI = 4,39; GII = 7,11 e GIII = 7,35. Após a descolagem foram realizadas fotografias das áreas de colagem, tanto dos dentes submetidos a testes in vivo quanto in vitro e ampliadas 5x para facilitar a visualização. As imagens obtidas foram analisadas, classificadas de acordo com o IAR e, por meio de gráficos de dispersão, foi verificada a relação entre a resistência ao cisalhamento e este índice. CONCLUSÃO: a média dos ensaios mecânicos realizados in vivo foi estatisticamente menor em relação aos ensaios in vitro. Não houve diferenças na resistência ao cisalhamento in vitro entre o grupo termociclado e o não-termociclado. Não houve relação entre tensão de ruptura e tipo de falha.

Stretched-exponential behavior and random walks on diluted hypercubic lattices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uma caracterização de grafos imersíveis

Este trabalho é motivado pelo resultado de Berge, que é uma generalização do teorema de Tutte o qual expressamos na forma: Dado o grafo G de ordem |V(G)| eni(G) o número de arestas em um emparelhamento máximo, existe um conjunto X de vértices de G tal que |V(G)|+|X| - ômega(G\X) - 2n(G)=0, onde ômega(G\X) é o número de componentes de ordem ímpar de G\X. Tal expressão chamamos a equação de Tutte-Berge associada de G, e escrevemos simplesmente T(G; X)=0. Os grafos podem ser classificados a partir das soluções da equação de Tutte-Berge. Um grafo G é chamado imersível se, e somente se, T(G; X)=0 possui pelo menos um conjunto solução não vazio de vértices, e G é denominado não imersível se, e somente se, o conjunto vazio é a única solução de T(G; X)=0. O resultado principal deste artigo é a caracterização de grafos imersíveis pelos conjuntos antifatores completos, além disso, provamos que os grafos fatoráveis estão contidos na classe dos imersíveis.

Scalar field theory at finite temperature in D=2+1

We discuss the phi(6) theory defined in D=2+1-dimensional space-time and assume that the system is in equilibrium with a thermal bath at temperature beta(-1). We use the 1/N expansion and the method of the composite operator (Cornwall, Jackiw, and Tomboulis) for summing a large set of Feynman graphs. We demonstrate explicitly the Coleman-Mermin-Wagner theorem at finite temperature.

Scalar field theory at finite temperature in D=2+1

We discuss the phi(6) theory defined in D = 2 + 1-dimensional space-time and assume that the system is in equilibrium with a thermal bath at temperature beta(-1). We use the 1/N expansion and the method of composite operator (CJT) for summing a large set of Feynman graphs. We demonstrate explicitly the Coleman-Mermin-Wagner theorem at finite temperature.