Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 31-32).

The topic of this thesis is occupancy mapping for mobile robots, with an emphasis on a novel method for continuous occupancy mapping using Gaussian processes. In the new method, spatial correlation is accounted for in a natural way, and an a priori discretization of the area to be mapped is not necessary as within most other common methods. The main contribution of this thesis is the construction of a Gaussian process library for C++, and the use of this library to implement the continuous occupancy mapping algorithm. The continuous occupancy mapping is evaluated using both simulated and real world experimental data. The main result is that the method, in its current form, is not fit for online operations due to its computational complexity. By using approximations and ad hoc solutions, the method can be run in real time on a mobile robot, though not without losing many of its benefits.

Aquesta tesi tracta l'estudi de protocols de comunicació quàntica amb sistemes devariable continua (CV). Els sistemes de CV són aquells descrits per coordenades canòniques conjugades $x$ i $p$ dotades amb un espai de Hilbert de dimensió infinita. Una classe especial de sistemes CV són, els anomenats estats Gaussians.Contràriament als sistemes discrets, els estats Gaussians entrellaçats no es podendestil·lar només amb operacions Gaussianes. No obstant va ser mostrat que, és possible extreure bits clàssics perfectament correlacionats per establir claus secretes aleatòries. Apropiadament modifiquem el protocol usant entrellaçament Gaussià bipartit per assolir la distribució de claus quàntiques de manera eficient i realista. Descrivim i demostrem la seguretat en front de diversos possibles atacs enla comunicació, detallant els recursos necessaris. També hem considerat un protocol tripartit simple conegut com Acord Bizantí. És un vell protocol de comunicació clàssica en el què els participants (amb possibles traïdors entre ells)només podem comunicar-se en parelles, mentre intenten arribar a una decisiócomú. Clàssicament hi ha un límit en el nombre màxim de traïdors que poden estar involucrats dins el joc. No obstant, una solució quàntica existeix. Mostrem aquestasolució dins els CV usant estats entrellaçats Gaussians multipartits i operacionsGaussianes. A més, mostrem sota quines premisses, entrellaçament contingut als estats, soroll, detectors ineficients, el nostre protocol és eficient i aplicable amb tecnologia actual. És conegut que tot i que el seu rol excepcional dins els estats CV, de fet, els estats Gaussians no són sempre els millors candidats per desenvolupar tasquesd'informació quàntica. Així, ataquem el problema de la quantificació de correlacions(clàssiques i/o quàntiques) entre dos modes CV (Gaussians i no Gaussians).Proposem definir les correlacions entre dos modes com el màxim numero de bits correlacionats extrets a través de mesures locals en les quadratures de cadamode. En els estats Gaussians, on l'entrellaçament és accessible a través de la seva matriu de covariança la nostra quantificació majoritza l'entrellaçament, reduint¬se a un monotó d'entrellaçament per estats purs. Per estats no Gaussians, com estats fotònics de Bell, estats foto-substrets i mescles d'estats Gaussians, la correlació de bits en quadratures mostra ser també una funció monòtona amb la negativitat. Aquesta quantificació dóna una operacional i factible manera de mesurar l'entrellaçament no Gaussià en experiments actuals mitjançant detecció homodine directa i sense necessitar una tomografia completa de l'estat amb lamateixa dificultat que si es tractes d'estats Gaussians. Finalment ens hem focalitzat amb col·lectivitats atòmiques descrites com CV. L'entrellaçament induït per la mesura entre dos col·lectivitats atòmiques macroscòpiques va ser reportat experimentalment al 2001. Allà, la interacció entreun únic pols làser apropant-se a través de dos col·lectivitats atòmiques separades espacialment combinat amb una mesura projectiva final en la llum permetia la creació d'entrellaçament EPR pur entre les dues col·lectivitats. Mostrem com generar, manipular i detectar entrellaçament mesoscopic entre un nombre arbitraride col·lectivitats a través d'una interfície llum-matèria quàntica no demolidora. Lanostra proposta s'extén d'una manera no trivial per entrellaçament multipartit (GHZ ide tipus clúster) sense la necessitat de camps magnètics locals. A més mostrem sorprenentment que, donat el caràcter irreversible de la mesura, la interacció de la col·lectivitat atòmica amb un segon feix de llum pot modificar e inclús revertir la acció d'entrellaçament del primer deixant la col·lectivitat en un estat separable. / This thesis deals with the study of quantum communication protocols with Continuous Variable (CV) systems. CV systems are those described by canonical conjugated coordinates $x$ and $p$ endowed with infinite dimensional Hilbertspaces, thus involving a complex mathematical structure. A special class of CVstates, are the so-called Gaussian states. We present a protocol that permits toextract quantum keys from entangled Gaussian states. Differently from discretesystems, Gaussian entangled states cannot be distilled with Gaussian operations only. However it was already shown, that it is still possible to extract perfectly correlated classical bits to establish secret random keys. We properly modify theprotocol using bipartite Gaussian entanglement to perform quantum key distribution in an efficient and realistic way. We describe and demonstrate security in front of different possible attacks on the communication, detailing the resources demanded. We also consider a simple 3-partite protocol known as Byzantine Agreement. It is anold classical communication problem in which parties (with possible traitors amongthem) can only communicate pairwise, while trying to reach a common decision. Classically, there is a bound in the maximal number of possible traitors that can be involved in the game. Nevertheless, a quantum solution exist. We show that solution within CV using multipartite entangled Gaussian states and Gaussian operations. Furthermore, we show under which premises concerning entanglement content of the state, noise, inefficient homodyne detectors, our protocol is efficient and applicable with present technology. It is known that in spite of their exceptional role within the space of all CV states, in fact, Gaussian states are not always the best candidates to perform quantum information tasks. Thus, we tackle the problem of quantification of correlations (quantum and/or classical) between two CV modes (Gaussian and non-Gaussian). We propose to define correlations between the two modes as the maximal number of correlated bits extracted via local quadrature measurements on each mode. On Gaussian states, where entanglement is accessible via their covariance matrix ourquantification majorizes entanglement, reducing to an entanglement monotone for pure states. For non-Gaussian states, such as photonic Bell states, photon subtracted states and mixtures of Gaussian states, the bit quadrature correlationsare shown to be also a monotonic function of the negativity. This quantification yields a feasible, operational way to measure non-Gaussian entanglement in currentexperiments by means of direct homodyne detection, without needing a complete state tomography with the same complexity as if dealing with Gaussian states. Finally we focus to atomic ensembles described as CV. Measurement induced entanglement between two macroscopical atomic samples was reported experimentally in 2001. There, the interaction between a single laser pulsepropagating through two spatially separated atomic samples combined with a final projective measurement on the light led to the creation of pure EPR entanglement between the two samples. We show how to generate, manipulate and detect mesoscopic entanglement between an arbitrary number of atomic samples through a quantum non-demolition matter-light interface. Our proposal extends in a non-trivialway for multipartite entanglement (GHZ and cluster-like) without needing local magnetic fields. Moreover, we show quite surprisingly that given the irreversiblecharacter of a measurement, the interaction of the atomic sample with a secondpulse light can modify and even reverse the entangling action of the first one leavingthe samples in a separable state.

No description available.

Modeling of electromagnetic wave propagation in terms of Gaussian beams (GBs) has been considered in recent years. The incident radiation is expanded in terms of GBs by means of the point matching method. The simultaneous equations can be solved directly to produce excitation coefficients that generate the approximate pattern of a known antenna. Two different types of antenna patterns have been approximated in terms of GBs: a truncated antenna pattern and a hyperbolic antenna pattern. The influence of the Gaussian beam parameters on the approximation process is clarified.

The thesis illustrates a DSP-based speaker recognition system . In order to make the modular within the representation floating-point, we simplify the algorithm. This speaker recognition system is including hardware setting and implementation of speaker algorithm. The DSP chip is float arithmetic DSP(ADSP-21161 of ADI SHARK Series) , the algorithm of speaker recognition is gaussian mixture model. According to result of experiments, the speaker recognition of DSP can gain good recognition and speed efficiency.

The thesis illustrates the development of DSP-based systems-¡§DSP Based Face Characteristic Extraction and Identity Recognition System¡¨.The principal system consists of three major subsystems and two kinds of structure of recognition algorithms.Three major subsystems are Image Acquisition System.Image Preprocessing System,and face characteristic extraction individually.Two kinds of structure are Competitive Neural Network and Gaussian mixture model respectively In actual proving,we adopt colored half-length face image alone only face image,and simulate on PC.In order to acquire the characteristic parameter with the different parts to the people faces , and then achieve the purpose that the identity discerns.Finally implant it to DSP .Shown by the experimental result,this system can really reach the anticipative goal,and gain good recognition and efficiency.

Ambient noise generated by surface random processes is the primary contribution to the noise-field energy in the intermediate frequency band, and thus is important in many applications of underwater sound. In this study, the noise field is analyzed with respect to the effects of random source spectrum, waveguide structure of the water column, and seabed stratification upon the noise-field intensity as well as spatial correlation. Based upon a noise-generation model due to continuous random sources, incorporating several analytical models for seabed stratification, a formulation may then be derived to facilitate the numerical implementation. Many results shall be generated and analyzed. In this study considers the noise field generated by surface random processes in an oceanic environment with a sediment layer possessing a continuously varying density and sound-speed profile. This model closely resembles the oceanic waveguide environment and therefore enables the simulation of surface noise generation. Many results of the noise field were generated, including the noise intensity distribution, vertical and horizontal correlations. It is demonstrated that the noise intensity may be affected by the stratification mainly through the continuous spectrum, in that the continuous spectrum is equally important as the normal modes in the present analysis. Moreover, the results for the correlations show that the noise field in the horizontal direction becomes more coherent when the noise sources are more correlated, while in the vertical direction, the results tend to reverse. The horizontal correlations of the noise field due to surface random sources with non-isotropic power spectrum, such as nonisotropic Gaussian and Pierson-Moskowitz, were generated and analyzed.

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Ambient noise generated by surface random processes is the primary contribution to the noise-field energy in the intermediate frequency band, and thus is important in many applications of underwater sound. In this study, the noise field is analyzed with respect to the effects of random source spectrum, waveguide structure of the water column, and seabed stratifica¬tion upon the noise-field intensity as well as spatial correlation. Based upon a noise-generation model due to continuous random sources, incorporating several analytical models for seabed stratification, a formulation may then be derived to facilitate the numerical implementation. Many results shall be generated and analyzed. In this study considers the noise field generated by wave in an oceanic environment with a sediment layer possessing a constant density and sound-speed profile. This model closely resembles the oceanic waveguide environment and therefore enables the simulation of surface noise generation. Many results of the noise field were generated, in¬cluding the noise intensity distribution, vertical and horizontal correlations. It is demonstrated that the noise intensity may be affected by the strat¬ification mainly through the continuous spectrum, in that the continuous spectrum is equally important as the normal modes in the present analysis. Moreover, the results for the correlations show that the noise field in the horizontal direction becomes more coherent when the noise sources are more correlated, while in the vertical direction, the results tend to reverse. The horizontal correlations of the noise field due to surface random sources with non-isotropic power spectrum, such as non-isotropic Gaussian and, were generated and analyzed.