Darbo tikslas - atlikti gęstančių sinusinių signalų modelių klasės įvertinimo metodų lyginamąją analizę, palyginant Kumaresan – Tufts ir DMUSIC metodus. Darbe trumpai aprašyta šių metodų teorinė dalis. Pagrindinis dėmesys skiriamas šių metodų eksperimentiniam palyginimui. Eksperimentams atlikti buvo sukurta grafinė vartotojo sąsaja MATLAB aplinkoje. Aprašyti atlikti eksperimentai skirti, polių tikslumo įvertinimo tyrimui bei slenkstinės SNR nustatymui. Nagrinėjami tiek lėtai gęstantys, tiek greitai gęstantys signalai. Pateikiami skaitinių eksperimentų rezultatai bei programiniai MATLAB kodai. / The aim of this study is the comparative analysis of damped sinusoidal signal model class estimation methods. Two methods – Kumaresan – Tufts and DMUSIC – are compared. Theoretical preliminaries of these methods are described briefly in the work. The main attention is paid to experimental comparison of these methods. In order to conduct experiments, a MATLAB graphical user interface was created. The experiments devoted to investigation of poles estimation accuracy and to determining of the threshold and SNR. Both slowly damped and quickly damped signals are considered. The results of numerical experiments are presented and MATLAB programs are given.

Bacillus cereus (Bc) et Bacillus thuringiensis (Bt) sont deux espèces génétiquement proches. Bc est une bactérie pathogène que peuvent causer des gastro-entérites d’origine aliméntaire. Bt est une bactérie entomopathogène, dont le cycle de vie dans la larve d’insecte est contrôlé par des systèmes de quorum sensing, comme le système Rap/Phr, que régule processus tels que la sporulation, la formation de biofilm et la conjugaison. La présence des ces genès a été identifiée dans les plasmides, et ces eleménts ont été associés à l’adaptation des spécies dans sont niche ecologique. Le but de cette étude est de comprendre le rôle des plasmides dans ces bactéries. Pour la première étude l’insecte larvae, le niche privilegie de Bt, ont été infectées par souches de Bc et Bt, avec un contenu plasmidique diffèrent. Le fitness a été evallué par le comptage de cellules végétatives et spores dans quatre temps. Les souches de Bt et Bc ont été classées dans cinq groups par rapport à sont fitness. Dans ces groups le plasmide a affecté le fitness de la bactérie positive ou négativement. Les résultats ont démontré que les souches du group du B. cereus que reçoivent a pathogène plasmid ne est pas suffisant pour une augmentation effectif de la population bactérienne, i.e., coloniser l’hôte. La deuxième étude a permis caractériser le système rap/phr porté par le plasmide cryptique pHT8_1. Les résultats démontrent que la protéine Rap8 inhibe la sporulation dans la l’insecte. L’activité de cette protéine est inhibée par le peptide de signalisation Phr8. Le système Rap/Phr8_1 a permis les bactéries exercer un strict contrôle sur la sporulation, un processus important pour assurer la survie et la dissémination des bactéries. L’ensemble des résultats de la deuxième étude montrent que les plasmides peuvent fournir avantages pour l’adaptation et evolution de B. thuringiensis dans son niche ecologique, alors que les résultats de la première étude indiqués que les souches de Bc group doivent avoir un contenu génétique approprié pour exhiber un fitness élévé en permettant une optimal multiplication and dissemination de populations bactérienne dans l’insect larvae. / Bacillus cereus (Bc) and Bacillus thuringiensis (Bt) are two closely related species. Bc is a pathogenic species responsible for gastroenteritis by food-borne. Bt is an entomopathogenic bacterium, which the lifecycle in insect larvae is controlled by quorum sensing systems, such as Rap/Phr, which regulates processes such as sporulation, biofilm formation and conjugation. The presence of these genes in plasmids has been described, furthermore, plasmids have been involved in bacterial adaptation to their ecological niche. In order to understand the role of the plasmids to these species, two complementary works were carried out. First, insect larvae, a privileged ecological niche of Bt strains, were infected with Bc and Bt strains harboring different plasmid contents. Their fitness were evaluated by vegetative cells and spore counts at four time points. Bt and Bc strains were classified into five groups according to the bacterial fitness. In these groups, the plasmid affects positively or negatively the bacterial fitness. The results demonstrated that for B. cereus group strains, getting a pathogenicity plasmid is not enough to effectively increase bacterial population, colonizing insect hosts. The second study characterized the rap/phr system encoded by the cryptic plasmid pHT8_1. The Rap8 protein inhibited the sporulation process in insect larvae. This protein was directly inhibited by the active signaling peptide Phr8. The Rap8/Phr8 system may allow the bacteria to exert a tight control of the sporulation process in the host cadaver for optimizing the multiplication, the survival and the dissemination of the bacteria. Thus, the results of the second study showed that the plasmids can provide advantages for the adaptation and the evolution of B. thuringiensis in its ecological niche, while the results of the first study indicate that B. cereus group strains must have a suitable genetic background to display a high fitness allowing optimal multiplication and dissemination of the bacterial population within insect larvae.

The demand for sophisticated wireless applications capable of conveying information content represented in various forms such as voice, data, audio and video is ever increasing. In order to support such applications, either additional wireless spectrum is needed or advanced signal processing techniques must be employed by the next-generation wireless communication systems. An immediate observation that can be made regarding the first option is that radio frequency spectrum is a limited natural resource. Moreover, since existing spectrum allocation policies of several national regulatory agencies such as the Federal Communications Commission (FCC) restrict spectrum access to licensed entities only, it has been identified that most of the licensed spectrum across time and frequency is inefficiently utilized. To facilitate greater spectral efficiency, many national regulatory agencies are considering a paradigm shift towards spectrum allocation by allowing unlicensed users to temporarily borrow unused spectral resources. This concept is referred to a dynamic spectrum access (DSA). Although, several spectrum measurement campaigns have been reported in the published literature for quantitatively assessing the available vacant spectrum, there are certain aspects of spectrum utilization that need a deeper understanding. First, we examine two complementary approaches to the problem of characterizing the usage of licensed bands. In the first approach, a linear mixed-effects based regression model is proposed, where the variations in percentage spectrum occupancy and activity period of the licensed user are described as a function of certain independent regressor variables. The second approach is based on the creation of a geo-location database consisting of the licensed transmitters in a specific geographical region and identifying the coverage areas that affect the available secondary channels. Both of these approaches are based on the energy spectral density data-samples collected across numerous frequency bands in several locations in the United States. We then study the mutual interference effects in a coexistence scenario consisting of licensed and unclicensed users. We numerically evaluate the impact of interference as a function of certain receiver characteristics. Specifically, we consider the unlicensed user to utilize OFDM or NOFDM symbols since the appropriate subcarriers can be turned off to facilitate non- contiguous spectrum utilization. Finally, it has been demonstrated that multiple-input and multiple-output (MIMO) antennas yield significant throughput while requiring no increase in transmit power or required bandwidth. However, the separation of spectrally overlapping signals is a challenging task that involves the estimation of the channel. We provide results concerning channel and symbol estimation in the scenario described above. In particular, we focus on the MIMO-OFDM transmission scheme and derive capacity lower bounds due to imperfect channel estimation.

We study nonlinear least-squares problem that can be transformed to linear problem by change of variables. We derive a general formula for the statistically optimal weights and prove that the resulting linear regression gives an optimal estimate (which satisfies an analogue of the Rao–Cramer lower bound) in the limit of small noise.

The effects of winds and/or waves on ship motions, forces, moments, maneuverability and controllability are investigated with URANS computations. The air/water flow computations employ a semi-coupled approach in which water is not affected by air, but air is computed assuming the free surface as a moving immersed boundary. The exact potential solution of waves/wind problem is modified introducing a logarithmic blending in air, and imposed as boundary and initial conditions. The turbulent air flows over 2D water waves are studied to investigate the effects of waves on incoming wind flow. Ship airwake computations are performed with different wind speeds and directions for static drift and dynamic PMM in calm water, pitch and heave in regular waves, and 6DOF motions in irregular waves simulating hurricane CAMILLE. Ship airwake analyses show that the vortical structures evolve due to ship motions and affect the ship dynamics significantly. Strong hurricane head and following winds affect up to 28% the resistance and 7% the motions. Beam winds have most significant effects causing considerable roll motion and drift forces, affecting the controllability of the ship. A harmonic wave group single run seakeeping procedure is developed, validated and compared with regular wave and transient wave group procedures. The regular wave procedure requires multiple runs, whereas single run procedures obtain the RAOs for a range of frequencies at a fixed speed, assuming linear ship response. The transient wave group procedure provides continuous RAOs, while the harmonic wave group procedure obtains discrete transfer functions, but without focusing. Verification and validation studies are performed for transient wave group procedure. Validation is achieved at the average interval of 9.54 (%D). Comparisons of the procedures show that harmonic wave group is the most efficient, saving 75.8% on the computational cost compared to regular wave procedure. Error values from all procedures are similar at 4 (%D). Harmonic wave group procedure is validated for a wide range of Froude numbers, with satisfactory results. Deterministic wave groups are used for three sisters rogue waves modeling. A 6DOF ship simulation is demonstrated which shows total loss of controllability with extreme ship motions, accelerations and structural loads.

Dans cette thèse, nous étudions divers problèmes statistiques liés à deux modèles paramétriques stochastiques que sont le mouvement brownien fractionnaire (mbf) et le mouvement brownien multifractionnaire (mbm). Le mbf a été introduit en statistique à partir de 1968 pour modéliser des phénomènes autosimilaires (i.e. invariants par changements d'échelle) et des séries chronologiques exhibant une structure de dépendance uniforme qui décroî t de manière hyperbolique avec le temps. Le mbm, apparu beaucoup plus récemment, constitue une extension du mbf au sens où la structure de dépendance peut évoluer au cours du temps : l'autosimilarité n'est alors vérifiée qu'asymptotiquement localement. L'objectif initial de ce travail de recherche a été l'identification de ce dernier modèle. Néanmoins, ce travail a nécessité des connaissances théoriques constituées par un traitement approfondi et pertinent du mbf, tant sur la compréhension des résultats obtenus jusqu'alors que sur leurs extensions.

<p>Navigation is about knowing your own position, orientation and velocity relative to some geographic entities. The sensor fusion considered in this thesis combines data from a dead reckoning system, inertial navigation system (INS), and measurements of the ground elevation. The very fast dynamics of aircraft navigation makes it difficult to estimate the true states. Instead the algorithm studied will estimate the errors of the INS and compensate for them. A height database is used along with the measurements. The height database is highly non-linear why a Rao-Blackwellized particle filter is used for the sensor fusion. This integrated navigation system only uses data from its own sensors and from the height database, which means that it is independent of information from outside the aircraft. </p><p>This report will describe the algorithm and illustrate the theory used. The main purpose is to evaluate the algorithm using real flight data, why the result chapter is the most important.</p>

<p>Periodic signal modeling plays an important role in different fields. The unifying theme of this thesis is using nonlinear techniques to model periodic signals. The suggested techniques utilize the user pre-knowledge about the signal waveform. This gives these techniques an advantage as compared to others that do not consider such priors.</p><p>The technique of Part I relies on the fact that a sine wave that is passed through a static nonlinear function produces a harmonic spectrum of overtones. Consequently, the estimated signal model can be parameterized as a known periodic function (with unknown frequency) in cascade with an unknown static nonlinearity. The unknown frequency and the parameters of the static nonlinearity are estimated simultaneously using the recursive prediction error method (RPEM). A treatment of the local convergence properties of the RPEM is provided. Also, an adaptive grid point algorithm is introduced to estimate the unknown frequency and the parameters of the static nonlinearity in a number of adaptively estimated grid points. This gives the RPEM more freedom to select the grid points and hence reduces modeling errors.</p><p>Limit cycle oscillations problem are encountered in many applications. Therefore, mathematical modeling of limit cycles becomes an essential topic that helps to better understand and/or to avoid limit cycle oscillations in different fields. In Part II, a second-order nonlinear ODE is used to model the periodic signal as a limit cycle oscillation. The right hand side of the ODE model is parameterized using a polynomial function in the states, and then discretized to allow for the implementation of different identification algorithms. Hence, it is possible to obtain highly accurate models by only estimating a few parameters.</p><p>In Part III, different user aspects for the two nonlinear approaches of the thesis are discussed. Finally, topics for future research are presented. </p>

Periodic signal modeling plays an important role in different fields. The unifying theme of this thesis is using nonlinear techniques to model periodic signals. The suggested techniques utilize the user pre-knowledge about the signal waveform. This gives these techniques an advantage as compared to others that do not consider such priors. The technique of Part I relies on the fact that a sine wave that is passed through a static nonlinear function produces a harmonic spectrum of overtones. Consequently, the estimated signal model can be parameterized as a known periodic function (with unknown frequency) in cascade with an unknown static nonlinearity. The unknown frequency and the parameters of the static nonlinearity are estimated simultaneously using the recursive prediction error method (RPEM). A treatment of the local convergence properties of the RPEM is provided. Also, an adaptive grid point algorithm is introduced to estimate the unknown frequency and the parameters of the static nonlinearity in a number of adaptively estimated grid points. This gives the RPEM more freedom to select the grid points and hence reduces modeling errors. Limit cycle oscillations problem are encountered in many applications. Therefore, mathematical modeling of limit cycles becomes an essential topic that helps to better understand and/or to avoid limit cycle oscillations in different fields. In Part II, a second-order nonlinear ODE is used to model the periodic signal as a limit cycle oscillation. The right hand side of the ODE model is parameterized using a polynomial function in the states, and then discretized to allow for the implementation of different identification algorithms. Hence, it is possible to obtain highly accurate models by only estimating a few parameters. In Part III, different user aspects for the two nonlinear approaches of the thesis are discussed. Finally, topics for future research are presented.

Navigation is about knowing your own position, orientation and velocity relative to some geographic entities. The sensor fusion considered in this thesis combines data from a dead reckoning system, inertial navigation system (INS), and measurements of the ground elevation. The very fast dynamics of aircraft navigation makes it difficult to estimate the true states. Instead the algorithm studied will estimate the errors of the INS and compensate for them. A height database is used along with the measurements. The height database is highly non-linear why a Rao-Blackwellized particle filter is used for the sensor fusion. This integrated navigation system only uses data from its own sensors and from the height database, which means that it is independent of information from outside the aircraft. This report will describe the algorithm and illustrate the theory used. The main purpose is to evaluate the algorithm using real flight data, why the result chapter is the most important.