Estudo da qualidade de serviço de uma aplicação VoIP em ambientes wireless com handoff

This work deals with experimental studies about VoIP conections into WiFi 802.11b networks with handoff. Indoor and outdoor network experiments are realised to take measurements for the QoS parameters delay, throughput, jitter and packt loss. The performance parameters are obtained through the use of software tools Ekiga, Iperf and Wimanager that assure, respectvely, VoIP conection simulation, trafic network generator and metric parameters acquisition for, throughput, jitter and packt loss. The avarage delay is obtained from the measured throughput and the concept of packt virtual transmition time. The experimental data are validated based on de QoS level for each metric parameter accepted as adequated by the specialized literature

Estudos de algumas ferramentas de coleta e visualização de dados e desempenho de aplicações paralelas no ambiente MPI

The last years have presented an increase in the acceptance and adoption of the parallel processing, as much for scientific computation of high performance as for applications of general intention. This acceptance has been favored mainly for the development of environments with massive parallel processing (MPP - Massively Parallel Processing) and of the distributed computation. A common point between distributed systems and MPPs architectures is the notion of message exchange, that allows the communication between processes. An environment of message exchange consists basically of a communication library that, acting as an extension of the programming languages that allow to the elaboration of applications parallel, such as C, C++ and Fortran. In the development of applications parallel, a basic aspect is on to the analysis of performance of the same ones. Several can be the metric ones used in this analysis: time of execution, efficiency in the use of the processing elements, scalability of the application with respect to the increase in the number of processors or to the increase of the instance of the treat problem. The establishment of models or mechanisms that allow this analysis can be a task sufficiently complicated considering parameters and involved degrees of freedom in the implementation of the parallel application. An joined alternative has been the use of collection tools and visualization of performance data, that allow the user to identify to points of strangulation and sources of inefficiency in an application. For an efficient visualization one becomes necessary to identify and to collect given relative to the execution of the application, stage this called instrumentation. In this work it is presented, initially, a study of the main techniques used in the collection of the performance data, and after that a detailed analysis of the main available tools is made that can be used in architectures parallel of the type to cluster Beowulf with Linux on X86 platform being used libraries of communication based in applications MPI - Message Passing Interface, such as LAM and MPICH. This analysis is validated on applications parallel bars that deal with the problems of the training of neural nets of the type perceptrons using retro-propagation. The gotten conclusions show to the potentiality and easinesses of the analyzed tools.

Roteamento em Redes de Sensores Sem Fios Com Base Em Aprendizagem Por Reforço

The use of wireless sensor and actuator networks in industry has been increasing past few years, bringing multiple benefits compared to wired systems, like network flexibility and manageability. Such networks consists of a possibly large number of small and autonomous sensor and actuator devices with wireless communication capabilities. The data collected by sensors are sent directly or through intermediary nodes along the network to a base station called sink node. The data routing in this environment is an essential matter since it is strictly bounded to the energy efficiency, thus the network lifetime. This work investigates the application of a routing technique based on Reinforcement Learning s Q-Learning algorithm to a wireless sensor network by using an NS-2 simulated environment. Several metrics like energy consumption, data packet delivery rates and delays are used to validate de proposal comparing it with another solutions existing in the literature

Análise de escalabilidade de uma implementação paralela do simulated annealing acoplado

This paper analyzes the performance of a parallel implementation of Coupled Simulated Annealing (CSA) for the unconstrained optimization of continuous variables problems. Parallel processing is an efficient form of information processing with emphasis on exploration of simultaneous events in the execution of software. It arises primarily due to high computational performance demands, and the difficulty in increasing the speed of a single processing core. Despite multicore processors being easily found nowadays, several algorithms are not yet suitable for running on parallel architectures. The algorithm is characterized by a group of Simulated Annealing (SA) optimizers working together on refining the solution. Each SA optimizer runs on a single thread executed by different processors. In the analysis of parallel performance and scalability, these metrics were investigated: the execution time; the speedup of the algorithm with respect to increasing the number of processors; and the efficient use of processing elements with respect to the increasing size of the treated problem. Furthermore, the quality of the final solution was verified. For the study, this paper proposes a parallel version of CSA and its equivalent serial version. Both algorithms were analysed on 14 benchmark functions. For each of these functions, the CSA is evaluated using 2-24 optimizers. The results obtained are shown and discussed observing the analysis of the metrics. The conclusions of the paper characterize the CSA as a good parallel algorithm, both in the quality of the solutions and the parallel scalability and parallel efficiency

Arquiteturas eficientes para sensoriamento espectral e classificação automática de modulações usando características cicloestacionárias

The increasing demand for high performance wireless communication systems has shown the inefficiency of the current model of fixed allocation of the radio spectrum. In this context, cognitive radio appears as a more efficient alternative, by providing opportunistic spectrum access, with the maximum bandwidth possible. To ensure these requirements, it is necessary that the transmitter identify opportunities for transmission and the receiver recognizes the parameters defined for the communication signal. The techniques that use cyclostationary analysis can be applied to problems in either spectrum sensing and modulation classification, even in low signal-to-noise ratio (SNR) environments. However, despite the robustness, one of the main disadvantages of cyclostationarity is the high computational cost for calculating its functions. This work proposes efficient architectures for obtaining cyclostationary features to be employed in either spectrum sensing and automatic modulation classification (AMC). In the context of spectrum sensing, a parallelized algorithm for extracting cyclostationary features of communication signals is presented. The performance of this features extractor parallelization is evaluated by speedup and parallel eficiency metrics. The architecture for spectrum sensing is analyzed for several configuration of false alarm probability, SNR levels and observation time for BPSK and QPSK modulations. In the context of AMC, the reduced alpha-profile is proposed as as a cyclostationary signature calculated for a reduced cyclic frequencies set. This signature is validated by a modulation classification architecture based on pattern matching. The architecture for AMC is investigated for correct classification rates of AM, BPSK, QPSK, MSK and FSK modulations, considering several scenarios of observation length and SNR levels. The numerical results of performance obtained in this work show the eficiency of the proposed architectures

Desenvolvimento de métodos construtivos e de novos materiais empregados na confecção de cartuchos de próteses de membros inferiores

The manufacture of prostheses for lower limb amputees (transfemural and transtibial) requires the preparation of a cartridge with appropriate and custom fit to the profile of each patient. The traditional process to the patients, mainly in public hospitals in Brazil, begins with the completion of a form where types of equipment, plugins, measures, levels of amputation etc. are identified. Currently, such work is carried out manually using a common metric tape and caliper of wood to take the measures of the stump, featuring a very rudimentary, and with a high degree of uncertainty geometry of the final product. To address this problem, it was necessary to act in two simultaneously and correlated directions. Originally, it was developed an integrated tool for viewing 3D CAD for transfemoral types of prostheses and transtibial called OrtoCAD I. At the same time, it was necessary to design and build a reader Mechanical equipment (sort of three-dimensional scanner simplified) able to obtain, automatically and with accuracy, the geometric information of either of the stump or the healthy leg. The methodology includes the application of concepts of reverse engineering to computationally generate the representation of the stump and/or the reverse image of the healthy member. The materials used in the manufacturing of prostheses nor always obey to a technical scientific criteria, because, if by one way it meets the criteria of resistance, by the other, it brings serious problems mainly due to excess of weight. This causes to the user various disorders due to lack of conformity. That problem was addressed with the creation of a hybrid composite material for the manufacture of cartridges of prostheses. Using the Reader Fitter and OrtoCAD, the new composite material, which aggregates the mechanical properties of strength and rigidity on important parameters such as low weight and low cost, it can be defined in its better way. Besides, it brings a reduction of up steps in the current processes of manufacturing or even the feasibility of using new processes, in the industries, in order to obtain the prostheses. In this sense, the hybridization of the composite with the combination of natural and synthetic fibers can be a viable solution to the challenges offered above

Adaptação eletrônica de um leitor mecânico de coto, investigação e desenvolvimento de interface CAD

Due to advances in the manufacturing process of orthopedic prostheses, the need for better quality shape reading techniques (i.e. with less uncertainty) of the residual limb of amputees became a challenge. To overcome these problems means to be able in obtaining accurate geometry information of the limb and, consequently, better manufacturing processes of both transfemural and transtibial prosthetic sockets. The key point for this task is to customize these readings trying to be as faithful as possible to the real profile of each patient. Within this context, firstly two prototype versions (α and β) of a 3D mechanical scanner for reading residual limbs shape based on reverse engineering techniques were designed. Prototype β is an improved version of prototype α, despite remaining working in analogical mode. Both prototypes are capable of producing a CAD representation of the limb via appropriated graphical sheets and were conceived to work purely by mechanical means. The first results were encouraging as they were able to achieve a great decrease concerning the degree of uncertainty of measurements when compared to traditional methods that are very inaccurate and outdated. For instance, it's not unusual to see these archaic methods in action by making use of ordinary home kind measure-tapes for exploring the limb's shape. Although prototype β improved the readings, it still required someone to input the plotted points (i.e. those marked in disk shape graphical sheets) to an academic CAD software called OrtoCAD. This task is performed by manual typing which is time consuming and carries very limited reliability. Furthermore, the number of coordinates obtained from the purely mechanical system is limited to sub-divisions of the graphical sheet (it records a point every 10 degrees with a resolution of one millimeter). These drawbacks were overcome by designing the second release of prototype β in which it was developed an electronic variation of the reading table components now capable of performing an automatic reading (i.e. no human intervention in digital mode). An interface software (i.e. drive) was built to facilitate data transfer. Much better results were obtained meaning less degree of uncertainty (it records a point every 2 degrees with a resolution of 1/10 mm). Additionally, it was proposed an algorithm to convert the CAD geometry, used by OrtoCAD, to an appropriate format and enabling the use of rapid prototyping equipment aiming future automation of the manufacturing process of prosthetic sockets.

Flotação por ar dissolvido para os minerais quartzo e feldspato utilizando coletores catiônicos

The pegmatite rocks in Rio Grande do Norte are responsible for much of the production of industrial minerals like quartz and feldspar. Quartz and feldspar are minerals from pegmatite which may occur in pockets with metric to centimetric dimensions or as millimetric to sub millimetric intergrowths. The correct physical liberation of the mineral of interest, in case of intergrowths, requires an appropriate particle size, acquired by size reduction operations. The method for treating mineral which has a high efficiency fines particles recovery is flotation. The main purpose of the present study is to evaluate the recovery of quartz and potassium feldspar using cationic diamine and quaternary ammonium salt as collectors by means of dissolved air flotation DAF. The tests were performed based on a central composite design 24, by which the influence of process variables was statistically verified: concentration of the quaternary ammonium salt and diamine collectors, pH and conditioning time. The efficiency of flotation was calculated from the removal of turbidity of the solution. Results of maximum flotation efficiency (60%) were found in the level curves, plotted in conditions of low concentrations of collectors (1,0 x 10-5 mol.L-1). These high flotation efficiencies were obtained when operating at pH 4 to 8 with conditioning time ranging from 3 to 5 minutes. Thus, the results showed that the process variables have played important roles in the dissolved air flotation process concerning the flotability of the minerals.

Diagnóstco geoambiental e avaliação de uso e ocupação do campo de dunas da zona especial de interesse turístco II (ZET-II) Natal/RN

The accelerated pressure of use and occupation of Rio Grande do Norte coastline in the last two decades presented the tourism as its main vector, having as a consequence a strong, articulated and growing real estate speculation of this area. In the Natal County there is a Zona Especial de Interesse Turistico II (Special Zone of Tourism Interest II) (ZET-II), consisted of urban beaches with approximately 8.5 km that is an important seashore of the city. The purpose of this research was identification, characterization and assessment of the process of use and occupation of dunes fields emphasizing the role of ZET-II, whereas the specific goals was the analysis of weather, geology and geomorphology, characterization of use and occupation of soil, and elaboration of an environmental diagnosis with identification and description of its mains consequences. The result of this work was the delineation of geologic-geomorphological map of the area with identification of principals units, determining its use and occupation, the measurement of the area already occupied by equipments, besides the description of the environmental impacts on dune fields: devastation, coastline erosion, ocean pollution by sewer and pluvial waters, contamination of groundwater, distribution inadequate of solid residues, landscape degradation, and occupation of seashore through the privatization of public areas. Concluding that the degrading changes occurred in this areas are resulting from the nature of use and urban seashore regulations, which have been diminishing the natural aspect, altering the landscape definitely, compromising the quality of hydro resources and altering its use, privatizing the areas between tides, complicating the population access and obstructing the scenery visualization of dunes and ocean. There is an urgent necessity of improvement of public politics in order to improve the strategies and organization of use and occupation of space urban-coastline

As Noites Mussetianas na Lírica Castroalvina

Ce mémoire de master a comme objectif étudier l influence du recueil Les Nuits d Alfred de Musset dans la poésie de Castro Alves. Nous allons procéder à une analyse textuelle des poèmes A volta da primavera , Murmúrios da tarde et Adeus à partir de la transposition des thèmes traités par le poète français dans La nuit d août , La nuit de mai et La nuit d octobre . A traves l intertextualité manifestée par des épigraphes de ces poèmes mussetiens, nous trouvons des ressemblances et dissemblances éventuelles qui assurent d un rapport entre ces deux auteurs. Le lyrisme romantique d orientation mélancolique établit des liens entre des poètes qui ont un concep cyclique du sentiment amoureux: de la naissance à la mort, et de celle-ci à la renaissance. La femme, qui se trouve liée aux événements naturels, change le paysage, sa présence étant une raison raison de joie et son absence, une souffrance. La nature évoquée et ses saisons servent de décor vivant aux penchants d états d esprit parmi les amants. Alors, nous verront dans le premier poème castroalvino l euphorie des noces printanières; La mélancolie éprouvée au déclin du jour et ses soupirs évanescents dans le deuxième poème; et dans le dernier, le deuil fermé d un amant qui resiste à accomplir le deuil de l objet d amour

Iracema: a alegoria da mãe genti(o)l

A abordagem da visão da literatura nacional dentro do contexto cultural brasileiro da segunda metade do século XIX e do posicionamento crítico de José de Alencar fez, de sua produção romanesca, especialmente a indianista, representada aqui por sua obra Iracema, um símbolo do conjunto de intenções nacionalistas que invadiu a alma e o coração de todo o povo, no que diz respeito ao sentimento de brasilidade , condizente com a estética romântica da qual faz parte seu autor. Seu posicionamento, quer seja crítico ou artístico, faz de Alencar o maior polemista em defesa da liberdade cultural e literária do Brasil, enquanto alguém bem consciente de sua função social, e por que não dizer, crítica, identificando a metalinguagem como um diferencial fomentador de uma teorização de poética na defesa de sua ficção, abrindo caminho, assim, para a pesquisa da poética explícita na sua produção artística. A referida análise buscará, a partir de uma análise estrutural das partes formais que o compõem esteticamente, como também de uma compreensão temática dos ditos e interditos utilizados pelo narrador alencariano na composição de seu discurso, identificar Iracema enquanto um romance que disputa o título de obra fundacional do Brasil. Para isso se faz necessário empreender uma abordagem do como e do quanto os elementos da Natureza, num romance romântico que tem a Natureza enquanto uma de suas temáticas mais significativas, podem constituir e interferir na percepção e construção de um personagem, que é todo Natureza, e no meio natural em que ele vive; até mesmo ser, por causa disso, o elemento mais representativo dessa nação que se deseja criar, trazendo para o cenário cultural brasileiro do século XIX uma versão de instituição baseada no revigoramento da memória da cultura selvagem. Faz-se lícito também animar forças da natureza e da terra-paisagem que poderiam ser tidas, apenas, como exóticas, mas que na obra em questão funcionam como protagonistas, mesmo fantasmas, de um pacto social e político que, mesmo quando rompe, recusa-se em deixar romper, mergulhando no espaço romanesco da magnitude das águas ou na frieza tumular da terra. Tomar-se-á, também, como ponto de estudo, a análise da fusão da experiência histórica com a experiência ficcional, observando o imbricamento de um discurso no outro, como também as fronteiras que se estabelecem a partir dessa tentativa; tomando o erotismo e a alegoria como pontos de convergência na obra em questão. Por meio da verificação de uma relação que se constrói a partir da solidão, da memória e do esquecimento em que acabam por mergulhar todos os seus personagens, que são, por vezes, tragados em algum dilúvio bíblico da purificação, dentro de um projeto audacioso de invenção de uma nação, que se quer de identidade cultural, e também política, mas que termina condenado ao silêncio, não gozando de liberdade em relação ao espaço a que pertence e, no entanto representa, só cabendo a eles regressarem para dentro da terra-mãe, ou se submeterem a um ritual de profunda aculturação, verificar-se-á, através desse discurso historicamente construído, o ideário de uma nação que se almejava projetar. O conflito de Iracema, personagem protagonista de sua obra homônima, a negação e a perda de si mesma, de tudo aquilo que poderia representar a sua identidade social e cultural, e, conseqüentemente, a morte e a vida dessa mãe genti(o)l, simbolizam a vida e a arte de um povo que, passando pelos embates da colonização, através de seus artistas rebeldes e românticos da Independência, que ilustraram, em grande síntese, a visão através da qual o homem do Novo Mundo foi vislumbrado, rabiscou a imagem da americanidade pelo discurso da História

O mercado imobiliário e a reinvenção da Ribeira, Natal - RN: verticalizar para renovar?

The real estate dynamic originates new spatial forms, which can determine new uses and new places. We tried to analyze this work, the spatial transformations in the Ribeira district, Natal / RN, due to the advancement of the housing market that is gradually transforming the landscape with the introduction of new types of housing, especially by verticalization. The verticalization of the neighborhood occurs almost at once, changing the local landscape. Notwithstanding this process, given the rapid growth of Natal in the last two decades and the strategic location of the neighborhood, it is pertinent to note that, if not the process of vertical integration, perhaps the neighborhood had been at the mercy of other urban interventions and other approach the real estate market. The research used as instruments interviews with actors who work in the property market in the town and representatives of organizations that have implemented major legislation in the area, the Instituto de Patrimônio Histórico e Artístico Nacional (IPHAN) and the Secretaria de Meio Ambiente e Urbanismo (SEMURB) as well as photographs on the area, in order to verify this new configuration that has been consolidated in the district. To support the theoretical discussion, there was a documentary and bibliographical research. In this way, the object of study of this search sees the uniqueness of urban renewal in the district of Ribeira and its relationship with the historic preservation laws and incentives for residential occupation in the neighborhood, especially regarding the vertical building

Estudo de sistemas complexos com interações de longo alcance : percolação, redes e tráfego

In this thesis we investigate physical problems which present a high degree of complexity using tools and models of Statistical Mechanics. We give a special attention to systems with long-range interactions, such as one-dimensional long-range bondpercolation, complex networks without metric and vehicular traffic. The flux in linear chain (percolation) with bond between first neighbor only happens if pc = 1, but when we consider long-range interactions , the situation is completely different, i.e., the transitions between the percolating phase and non-percolating phase happens for pc < 1. This kind of transition happens even when the system is diluted ( dilution of sites ). Some of these effects are investigated in this work, for example, the extensivity of the system, the relation between critical properties and the dilution, etc. In particular we show that the dilution does not change the universality of the system. In another work, we analyze the implications of using a power law quality distribution for vertices in the growth dynamics of a network studied by Bianconi and Barabási. It incorporates in the preferential attachment the different ability (fitness) of the nodes to compete for links. Finally, we study the vehicular traffic on road networks when it is submitted to an increasing flux of cars. In this way, we develop two models which enable the analysis of the total flux on each road as well as the flux leaving the system and the behavior of the total number of congested roads

Diagnóstico geoambiental com uso do geoprocessamento visando a determinação de potencialidades de uso do solo para a área estuarina do Rio Curimataú - Canguaretama(RN)

The activities developed in the coastal zone always arise the researchers interest, mainly when it is developed in fragile ecological areas, not observing the sustenable development laws. In this context, the analysis presented developed around the estuary of Curimatau river, located in the Eastern coast of Rio Grande do Norte state, integrates information provided by high resolution images of orbital remote sensing (IKONOS II, dated of July of 2003) and images of not-orbital remote sensing (Air photographs of DPU, dated of March of 1997) in a multitemporary perspective, diagnosising patterns of use and occupation, evaluating the main area´s impacts, together with the estuarian region fisiograph of Curimatau river. The use of high resolution images consequently allowed generates a precision cartography, facilitating the quantification of the evolution of the landscape and supporting decisions. Was possible yet, the definition of use areas, conservation areas and preservation areas; that were inserted in the concept of Potentialities: a fundamental element to management of vulnerable areas of the natural point of view. The information provided during the research had been stored in an Enviromental Georreferenced Data Base, constructed under the optics of Geographical Information Systems (GIS), that they facilitate the environment management Through fast access to information. The results were satisfactory, because permits the quantification of evolution of the landscape and the mapping. Beyond the geoenviromental diagnosis, was possible develop maps and matrixes that support the Rio Grande do Norte state costal Management.

A construção da natureza saudável: Natal 14900-1930

The Brazilian city of Natal, located between river, sea and dunes, rises up as a peculiar, unique landscape. A landscape made by the junction of what we can call two natures, the first one most known as "native" and the other properly recognized as antr6pica. This landscape has been changing throughout the time as a result of human working activities. In this process of landscape changing, some influent people such as medicine doctors, people from govemment, and also technicians took place and gave their contributions based on hygiene and salubrity principles, since the early years of xx century. They intended to bring up to the Natal s citzens a legacy of new concept of healthier life, as free as possible from pathogenic agents