With the rapid growth of wireless communications, the demand for the various multimedia services is increasing day by day leading to a deficit in the frequency spectrum resources. To overcome this problem, the concept of cognitive radio technology has been proposed which allows the unlicensed secondary user (SU) to access the licensed spectrum of the primary user (PU), thus improving the spectrum utilization. Cooperative communications is another emerging technology which is capable of overcoming many limitations in wireless systems by increasing reliability and coverage. The transmit and receive diversity techniques such as orthogonal space–time block codes (OSTBCs) and selection combining (SC) in multiple-input multiple-output (MIMO) cognitive amplify and forward relay networks help to reduce the effects of fading, increase reliability and extend radio coverage.   In this thesis, we consider a MIMO cognitive cooperative radio network (CCRN) with multiple relays. The protocol used at the relays is an amplify and forward protocol. At the receiver, the SC technique is applied to combine the signals. Analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of the signal-to-noise ratio (SNR) are derived. On this basis, the performance in terms of outage probability is obtained. Mathematica has been used to generate numerical results from the analytical expressions. The system model is simulated in MATLAB to verify the numerical results. The performance analysis of the system model is hence done in terms of outage probability.

The Feynman path integral formulation of quantum mechanics is a path integral representation for a propagator or probability amplitude in going between two points in space-time. The wave function is expressed in terms of an integral equation from which the Schrodinger equation can be derived. On taking the limit h — 0, the method of stationary phase can be applied and Newton's second law of motion is obtained. Also, the condition the phase vanishes leads to the Hamilton - Jacobi equation. The secondary objective of this paper is to study ways of relating quantum mechanics and classical mechanics. The Ehrenfest theorem is applied to a particle in an electromagnetic field. Expressions are found which are the hermitian Lorentz force operator, the hermitian torque operator, and the hermitian power operator.

Postcards highlight the most invigorating, awesome and memorable aspects of events and places. They serve as mementos to be shared or as a testament to experience, proof that "I was here." While postcards were most widely used at the turn of the 20th century, they are quickly being outmoded by the immediacy of technology. Thanks to digital photography and the world wide web, sharing memories is something that happens almost as quickly as the original event is experienced. The history and function of postcards are not the topics that I will address in this essay. Rather, I will look at how geography and experience influence the formation of memories and illustrate how postcards, in highlighting the most mundane and forgettable aspects of place, can act as a mnemonic device. I will also touch on ideas of the simulacra to explore how the simulation of an event or object can be truer or at least more authentic than the original.

The design and analysis of various distributed space time block coding schemes for cooperative relay networks is considered in this thesis. Rayleigh frequency flat and selective fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing (OFDM) type transmission approach are employed to mitigate synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. A novel detection scheme is then proposed for decode-and-forward and amplify-and-forward networks with closed-loop extended orthogonal coding and closed-loop quasi-orthogonal coding which reduce the computational complexity of the parallel interference cancellation. The near-optimum detector is presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approach and its ability to mitigate synchronization errors.

Master of Science / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Space-time coding (STC) schemes for Multiple Input Multiple Output (MIMO) systems have been an area of active research in the past decade. In this thesis, we propose a novel design of Space-Time Block Codes (STBCs) using Redundant Residue Number System (RRNS) codes, which are ideal for high data rate communication systems. Application of RRNS as a concatenated STC scheme to a MIMO wireless communication system is the main motivation for this work. We have optimized the link between residues and complex constellations by incorporating the “Direct Mapping” scheme, where residues are mapped directly to Gray coded constellations. Knowledge of apriori probabilities of residues is utilized to implement a probability based “Distance-Aware Direct Mapping” (DA) scheme, which uses a set-partitioning approach to map the most probable residues such that they are separated by the maximum possible distance. We have proposed an “Indirect Mapping” scheme, where we convert the residues back to bits before mapping them. We have also proposed an adaptive demapping scheme which utilizes the RRNS code structure to reduce the ML decoding complexity and improve the error performance. We quantify the upper bounds on codeword and bit error probabilities of both Systematic and Non-systematic RRNS-STBC and characterize the achievable coding and diversity gains assuming maximum likelihood decoding (MLD). Simulation results demonstrate that the DA Mapping scheme provides performance gain relative to a Gray coded direct mapping scheme. We show that Systematic RRNS-STBC codes provide superior performance compared to Nonsystematic RRNS-STBC, for the same code parameters, owing to more efficient binary to residue mapping. When compared to other concatenated STBC and Orthogonal STBC (OSTBC) schemes, the proposed system gives better performance at low SNRs.

Abstract The collective field theory technique provides a method of tackling problems with two N × N matrices in the large N limit. The collective field background from one matrix is first found, then the second matrix is introduced into this background as an impurity. Within the context of the AdS/CFT correspondence, this technique can be used to describe gauge theory states in the BMN limit. This dissertation starts by developing the collective field theory technique, firstly in general variables, then for one matrix, and subsequently for two matrices. It goes on to introduce a Yang-Mills interaction term, where two variable identifications are considered. The first is the more traditional angular momentum eigenstate model. The second is a model that directly uses two of the Higgs scalars. This model has been mentioned in the literature, but has not been considered in great depth. The exact two impurity spectrum is found, and the multi-impurity spectrum is found to first order. The resulting energy values match a spectrum that has been found for giant magnons.

Incoherent scatter radar (ISR) systems allow researchers to peer into the ionosphere via remote sensing of intrinsic plasma parameters. ISR sensors have been used since the 1950s and until the past decade were mainly equipped with a single mechanically steerable antenna. As such, the ability to develop a two or three dimensional picture of the plasma parameters in the ionosphere has been constrained by the relatively slow mechanical steering of the antennas. A newer class of systems using electronically steerable array (ESA) antennas have broken the chains of this constraint, allowing researchers to create 3-D reconstructions of plasma parameters. There have been many studies associated with reconstructing 3-D fields of plasma parameters, but there has not been a systematic analysis into the sampling issues that arise. Also, there has not been a systematic study as to how to reconstruct these plasma parameters in an optimum sense as opposed to just using different forms of interpolation. The research presented here forms a framework that scientists and engineers can use to plan experiments with ESA ISR capabilities and to better analyze the resulting data. This framework attacks the problem of space-time sampling by ESA ISR systems from the point of view of signal processing, simulation and inverse theoretic image reconstruction. We first describe a physics based model of incoherent scatter from the ionospheric plasma, along with processing methods needed to create the plasma parameter measurements. Our approach leads to development of the space-time ambiguity function, forming a theoretical foundation of the forward model for ISR. This forward model is novel in that it takes into account the shape of the antenna beam and scanning method along with integration time to develop the proper statistics for a desired measurement precision. Once the forward model is developed, we present the simulation method behind the Simulator for ISR (SimISR). SimISR uses input plasma parameters over space and time and creates complex voltage samples in a form similar to that produced by a real ISR system. SimISR allows researchers to evaluate different experiment configurations in order to efficiently and accurately sample specific phenomena. We present example simulations using input conditions derived from a multi-fluid ionosphere model and reconstructions using standard interpolation techniques. Lastly, methods are presented to invert the space-time ambiguity function using techniques from image reconstruction literature. These methods are tested using SimISR to quantify accurate plasma parameter reconstruction over a simulated ionospheric region.

Os processos espaço-temporais vêm ganhando destaque nos últimos anos, em razão do aumento de estudos compreendendo variáveis que apresentam interação entre as dimensões espacial e temporal. Com o objetivo de modelar esses processos, Pfeifer e Deutsch (1980a) propuseram uma extensão da classe de modelos univariados de Box-Jenkins, denominada por modelo espaço-temporal autoregressivo de média móvel (STARMA). Essa classe de modelos é utilizada para descrever dados de séries temporais espacialmente localizadas. Os processos passíveis de modelagem via classe de modelos STARMA são caracterizados por observações de variáveis aleatórias, em que os locais a serem incorporados no modelo são fixos no espaço. A dependência entre as n séries temporais é modelada por meio da matriz de ponderação, de modo que os modelos da classe STARMA expressem cada observação no tempo t e na localização i como uma média ponderada de combinações lineares das observações anteriores e a inovação defasada no espaço e no tempo conjuntamente. Dada a nova classe de modelos, os objetivos deste estudo foram apresentar a classe de modelos STARMA, implentar computacionalmente, no software R, rotinas que permitam a análise de dados espaço-temporais, com as rotinas implementadas estabelecer e testar modelos de séries temporais aos dados de temperaturas mínimas médias mensais de 8 estações meteorológicas situadas no Paraná e comparar a classe de modelos STARMA com a classe de modelos univariados proposta por Box e Jenkins (1970). Com este estudo verificou-se que na apresentação da classe de modelos STARMA há complexidade no conceito de ordens de vizinhança e na identificação dos modelos espaço-temporais. Em relação a criação de rotinas responsáveis pelas análises de dados espaço-temporais observou-se dificuldades em sua implementação, principalmente no momento de estimação dos parâmetros. Na comparação da classe de modelos STARMA, multivariada, com a classe de modelos SARIMA, univariada, constatou-se que ambos os modelos se ajustaram de maneira satisfatória aos dados, produzindo previsões acuradas. / Spatio-temporal processes have been highlighted lately, due to the increase of studies approaching variables that present interactions between the spatial and temporal dimensions. In order to model these processes, Pfeifer e Deutsch (1980a) have suggested an extension of the Box-Jenkins univariate model class, named spatio-temporal autoregressive moving-average model (STARMA). This model class is used to describe spatially located time series data. The processes prone to be modeled via the STARMA model class are characterized by observations of random variables, in which the locations to be incorporated in the model are spatially fixed. The dependence between the n time series is modeled through the weighing matrix. So STARMA models express each observation at time t and location i as a weighed mean of linear combinations of the previous observations and the jointly lagged innovation in space and time. Given the new class models, the objectives of this study were to present a class of models STARMA, implentar computationally, in textit R software, routines that allow the analysis of spatio-temporal data with the routines implemented to establish and test models time series data of monthly average minimum temperatures of 8 meteorological stations located in Paraná and compare the class of models STARMA with the class of univariate models proposed by Box e Jenkins (1970). With this study it was found that the presentation of the class of models STARMA no complexity in the concept of ordered neighborhood and identification of spatio-temporal models. Regarding the creation of routines responsible for the analysis of spatio-temporal observed difficulties in its implementation, especially at the time of estimation of parameters. In comparison class STARMA models, multivariate, with the class of SARIMA models, univariate, it was found that both models were adjusted satisfactorily to the data, producing accurate forecasts.

O transporte de contêineres é um serviço essencial no transporte global, apresentando uma rápida taxa de crescimento na sua utilização quando comparado com outros modos de transporte convencionais. Nesse contexto, o problema de roteirização de cargas de contêineres e o problema de reposicionamento de contêineres vazios são altamente correlacionados, sugerindo a necessidade de uma formulação conjunta adaptada para otimizar o sistema. Esta tese apresenta uma nova sistemática para seleção de cargas, alocação de cargas e reposicionamento de contêineres vazios em apoio às decisões operacionais no gerenciamento do transporte de contêineres por companhia de transporte regular em modal marítimo. O modelo proposto possibilita selecionar cargas e decidir por alternativas de rotas, além de reposicionar os contêineres vazios. O modelo integrado visa maximizar a margem de contribuição no transporte de contêineres para uma demanda fixa de múltiplos tipos de contêineres por uma rede de transporte em um horizonte de tempo particular, como uma rede espaço-tempo em um modelo de rede de fluxo máximo com restrições adicionais de alocação de requisições de cargas em caminhos nas rotas conhecidas. Foram criadas instâncias consistentes com a realidade considerando diferentes demandas fixas e estoques de contêineres. Os resultados mostram a flexibilidade e aplicabilidade do modelo para solucionar este problema de decisão complexo. / Container shipping is an essential service in global trade, presenting a fast-growing rate of utilization when compared to other conventional shipping modes. In this context, the cargo container routeing and empty repositioning container problems considering maritime liner companies are highly related, suggesting the need for a joint formulation tailored to optimize the system. This Thesis proposes a novel approach for cargoes acceptance in routes and empty container repositioning in support to decisions in the container transporting management by liner shipping companies in maritime transport modal. The proposed model decides by cargo acceptance or rejection to transport in known routes, in addition to reposition the empty containers. The integrated model maximises the contribution margin for fixed demand of multiples types of containers by a transport network in a particular season as a space-time network based on a max-flow network model with additional constraints of cargoes requisitions allocation in fixed route paths. We defined instances consistent with reality considering different fixed demands and inventory of containers. The results show the flexibility and applicability of this model to solve this complex decision problem.

A partir da constatação da existência da propriedade do espaço e tempo próprio de vida dos objetos na Natureza, defenderemos a tese da produção de espaço humano e da paisagem como sendo uma imagem e representação de espaço. Com a apropriação da propriedade do espaço e tempo próprio de vida dos objetos que o homem produz um espaço no qual vive e se reproduz, assim como representa este mesmo espaço através da paisagem. Este espaço produzido pelo homem denominamos Espaço Humanizado, já a paisagem, que representa este espaço, denominamos Paisagem Humanizada. A partir desta tese faremos algumas reflexões sobre paisagem como imagem e representação da produção de espaço através do estudo das paisagens pintadas nas iconografias, relatadas em viagens e memórias de viajantes, naturalistas e habitantes que durante a primeira metade dos séculos XIX estiveram ou viveram na cidade de São Paulo.. Nessa abordagem priorizaremos o aspecto do trabalho humano escravo indígena e negros africanos, do modo de habitar e conviver na cidade e da análise das pinturas de paisagem como documento histórico / This work deals with the humanization of space and landscape. This humanization results from the human appropriation of the space and time attributes of the objects which support the human space, where humans live and reproduce themselves. Besides, we discuss the urbanization of Sao Paulo between the centuries XVIII and XIX. The approach emphasizes the aspects related to human labor, architecture and production apparatus