Preservation of large tracts of habitat is often recommended for long-term population viability of area-sensitive species. Large tracts may not always be available. Smaller patches, though not able to contain a viable population individually, may contribute to overall regional population viability if within the small patches pairs could successfully reproduce. By definition, area-sensitive species should have a minimum patch size threshold of habitat below which they will not likely reproduce. Two potential causes for positive relationships between patch size and production are inverse relationships between patch size and brood parasitism and patch size and food availability. My objectives were (1) to determine the minimum patch size thresholds of reproductive success for golden-cheeked warblers (Dendroica chrysoparia), black-and-white warblers (Mniotilta varia), and white-eyed vireos (Vireo griseus); (2) to determine whether thresholds for occupancy, territory establishment by males, or pairing success were indicative of thresholds of reproduction; (3) to determine whether the proportion of pairs fledging brown-headed cowbird (Molothrus ater) young was related to patch size, and (4) to determine the affects of patch size on food availability (i.e., arthropod abundance). The Vickery index of reproductive activity was used to determine reproductive activity of each male or pair and to quantify parasitism occurrences. I collected arthropods using branch clipping to assess the relationship between patch size and arthropod abundance. I found minimum patch size thresholds of reproductive success for golden-cheeked and black-and-white warblers, but not for white-eyed vireos. Minimum patch size of reproductive success was between 15 and 20.1 ha. Minimum patch size thresholds for occupancy, territory establishment by males, and pair formation were not consistent with thresholds for reproductive success. I found no relationships between patch size and cowbird parasitism or patch size and arthropod biomass. Conservation practices for target species based on thresholds of occupancy, territory establishment, or pair formation may not address issues of reproduction. The ability to identify thresholds of reproductive success for target species could be useful in conservation and management in multiple ways including setting goals for retention and restoration of a target species’ habitat patch size.

Preservation of large tracts of habitat is often recommended for long-term population viability of area-sensitive species. Large tracts may not always be available. Smaller patches, though not able to contain a viable population individually, may contribute to overall regional population viability if within the small patches pairs could successfully reproduce. By definition, area-sensitive species should have a minimum patch size threshold of habitat below which they will not likely reproduce. Two potential causes for positive relationships between patch size and production are inverse relationships between patch size and brood parasitism and patch size and food availability. My objectives were (1) to determine the minimum patch size thresholds of reproductive success for golden-cheeked warblers (Dendroica chrysoparia), black-and-white warblers (Mniotilta varia), and white-eyed vireos (Vireo griseus); (2) to determine whether thresholds for occupancy, territory establishment by males, or pairing success were indicative of thresholds of reproduction; (3) to determine whether the proportion of pairs fledging brown-headed cowbird (Molothrus ater) young was related to patch size, and (4) to determine the affects of patch size on food availability (i.e., arthropod abundance). The Vickery index of reproductive activity was used to determine reproductive activity of each male or pair and to quantify parasitism occurrences. I collected arthropods using branch clipping to assess the relationship between patch size and arthropod abundance. I found minimum patch size thresholds of reproductive success for golden-cheeked and black-and-white warblers, but not for white-eyed vireos. Minimum patch size of reproductive success was between 15 and 20.1 ha. Minimum patch size thresholds for occupancy, territory establishment by males, and pair formation were not consistent with thresholds for reproductive success. I found no relationships between patch size and cowbird parasitism or patch size and arthropod biomass. Conservation practices for target species based on thresholds of occupancy, territory establishment, or pair formation may not address issues of reproduction. The ability to identify thresholds of reproductive success for target species could be useful in conservation and management in multiple ways including setting goals for retention and restoration of a target species’ habitat patch size.

In this thesis, two-dimensional (2-D) direction-of-arrival (DOA) estimation problem is considered. Usually, DOA estimation is considered in one dimension assuming a fixed elevation angle. While this assumption simplifies the problem, both the azimuth and elevation angles, namely, the 2-D DOA estimates are required in practical scenarios. In this thesis, planar array structures are considered for 2-D DOA estimation. In this context, V-shaped arrays are discussed and some of the important features of these arrays are outlined. A new method for the design of V-shaped arrays is presented for both isotropic and directional beam patterns. The design procedure is simple and can be applied for both uniform and nonuniform V-shaped sensor arrays. Closed form expressions are presented for the V-angle in order to obtain isotropic angle performance. While circular arrays have the isotropic characteristics, V-shaped arrays present certain advantages due to their large aperture for the same number of sensors and inter-sensor distance. The comparison of circular and V-shaped arrays is done by considering the azimuth and elevation Cramer-Rao Bounds (CRB). It is shown that V-shaped and circular arrays have similar characteristics for the sensor position errors while the uniform isotropic (UI) V-array performs better when there is mutual coupling and the sources are correlated. In the literature, there are several techniques for 2-D DOA estimation. Usually, fast algorithms are desired for this purpose since a search in two dimensions is a costly process. These algorithms have a major problem, namely, the pairing of the azimuth-elevation couples for multiple sources. In this thesis, a new fast and effective technique for this purpose is proposed. In this technique, a virtual array output is generated such that when the ESPRIT algorithm is used, the eigenvalues of the rotational transformation matrix have the 2-D angle information in both magnitude and phase. This idea is applied in different scenarios and three methods are presented for these cases. In one case, given an arbitrary array structure, array interpolation is used to generate the appropriate virtual arrays. When the antenna mutual coupling is taken into account, a special type of array structure, such as circular, should be used in order to apply the array interpolation. In general, the array mutual coupling matrix (MCM) should have a symmetric Toeplitz form. It is shown that the 2-D DOA performance of the proposed method approaches to the CRB by using minimum number of antennas in case of mutual coupling. This method does not require the estimation of the mutual coupling coefficients. While this technique is effective, it has problems especially when the number of sources increases. In order to improve the performance, MCM is estimated in the third approach. This new approach performs better, but it cannot be used satisfactorily in case of multipath signals. In this thesis, the proposed idea for fast 2-D DOA estimation is further developed in order to solve the problem when mutual coupling and multipath signals jointly exist. In this case, real arrays with some auxiliary sensors are used to generate a structured mutual coupling matrix. It is shown that the problem can be effectively solved when the array structure has a special form. Specifically, parallel uniform linear arrays (PULA) are employed for this purpose. When auxiliary sensors are used, a symmetric banded Toeplitz MCM is obtained for the PULA. This allows the application of spatial smoothing and ESPRIT algorithm for 2-D DOA estimation. The proposed algorithm uses triplets and presents closed form paired 2-D DOA estimates in case of unknown mutual coupling and multipath signals. Several simulations are done and it is shown that the proposed array structure and the method effectively solve the problem.

L’oxydoréduction de monocouches auto-assemblées (SAMs) de ferrocénylalcanethiolates à la surface d’or (FcRSAu) a été étudiée en temps réel par la spectroscopie de résonance de plasmons de surface couplée avec l’électrochimie (E-SPR). La sensibilité de cette technique permet de déterminer des changements d’épaisseur de couche l’ordre de quelques angström résultant d’un changement de structure de la SAM. Plusieurs études antérieures ont proposé que l’oxydation électrochimique d’une SAM de FcRSAu induit une réorientation moléculaire. L’E-SPR est utilisé pour identifier l’origine de ce changement structurel. D’abord, une calibration du réfractomètre SPR utilisé a été effectuée afin de trouver une équation de conversion du signal SPR obtenu en pixel en angle d’incidence pour que l’on puisse calculer le changement d’épaisseur de monocouche à partir du changement d’angle de résonance avec le modèle de Fresnel. Par la suite, une caractérisation approfondie des SAMs de FcCnSAu (où n = 6, 8, 12, 14) en contact avec du NaClO4 acidifié a été réalisée par électrochimie, éllipsométrie, spectroscopie infrarouge et microscopie à force atomique. Les résultats obtenus montrent que l’augmentation de la longueur des chaînes alkyles donne des SAMs de ferrocènes plus épaisses et moins désordonnées. L’analyse par l’E-SPR de ces SAMs pures montre que le changement d’épaisseur induit par l’électro-oxydation dépend linéairement du nombre de méthylènes sur la chaîne alkyle. En appliquant la déconvolution mathématique aux voltampérogrammes cycliques enregistrés pour les SAM mixtes (FcC12SAu/C11SAu) de différentes compositions, on arrive à la conclusion qu’il y a un redressement des chaînes alkyles dans les domaines des ferrocènes agrégés mais la réorientation des têtes de ferrocène dans les domaines de ferrocènes agrégés ou dispersés ne peut pas être exclue. Enfin, l’effet de l’anion électrolytique sur le changement d’épaisseur de la SAM mesuré par l’E-SPR a été étudié. L’analyse électrochimique montre que la capacité de pairage d’anions avec les ferrocéniums décroit comme suit : PF6- > ClO4- > BF4- > NO3-. Tandis que l’épaisseur de la SAM donnée par le changement d’angle de résonance suit la tendance suivante : NO3- ≥ ClO4- > PF6- ≈ BF4-. Des études plus approfondies seront nécessaire pour clarifier cette tendance observée par E-SPR. / The oxidation and reduction of self-assembled ferrocenylalkanethiolate monolayers formed on gold surfaces (FcRSAu) have been followed in real-time by electrochemical surface plasmon resonance (E-SPR) spectroscopy. Film thickness changes on the order of angstroms resulting from SAM structural changes can be detected by SPR. The electrochemically-induced reorientation of the ferrocenylalkanethiolates has been proposed by several spectroelectrochemistry studies. We have used E-SPR to elucidate the nature of the molecular reorientations. The SPR refractometer was first calibrated to find a pixel to angle equation so that Fresnel modeling could be used to calculate SAM thickness changes from the measured resonance angle changes (Δθmin). SAMs of FcCnSAu (where n = 6, 8, 12, 14) were characterized by electrochemistry, infrared spectroscopy and atomic force microscopy. The results obtained show that an increase in the alkyl chain length gives a thicker and less disordered SAM. Oxidation of the surface-bound ferrocenes to ferroceniums and pairing with ClO4- anions produces a similar change in Δθmin for these SAMs, but the variation in the SAM thickness is linearly dependent on the chain length. Mathematical deconvolution of the cyclic voltammograms of binary SAMs (FcC12SAu/C11SAu) of different compositions was used to separate the contributions of the different ferrocene domains (aggregated vs. isolated ferrocenes). We conclude that the aggregated-ferrocenes undergo a change in the orientation of the alkyl chain orientation. We cannot however exclude that the cyclopentadiene rings also reorient themselves. Anion pairing effect was studied by E-SPR. Our electrochemistry results indicate that the ability of the electrolyte anion to pair with the electrogenereted ferrocenium decreases in the following order: PF6- > ClO4- > BF4- > NO3-. On the other hand, the change in Δθmin does not follow the associated trend observed for the anion pairing capacity but rather NO3- ≥ ClO4- > PF6- ≈ BF4-. We hypothesize that the difference in the uptake water molecules by the oxidized SAM may be the reason for this observation. This hypothesis still needs to be verified.

Secure communication is critical to many applications. To this end, various security goals can be achieved using elliptic/hyperelliptic curve and pairing based cryptography. Polynomial multiplication is used in the underlying operations of these protocols. Therefore, as part of this thesis different recursive algorithms are studied; these algorithms include Karatsuba, Toom, and Bernstein. In this thesis, we investigate algorithms and implementation techniques to improve the performance of the cryptographic protocols. Common factors present in explicit formulae in elliptic curves operations are utilized such that two multiplications are replaced by a single multiplication in a higher field. Moreover, we utilize the idea based on common factor used in elliptic curves and generate new explicit formulae for hyperelliptic curves and pairing. In the case of hyperelliptic curves, the common factor method is applied to the fastest known even characteristic hyperelliptic curve operations, i.e. divisor addition and divisor doubling. Similarly, in pairing we observe the presence of common factors inside the Miller loop of Eta pairing and the theoretical results show significant improvement when applying the idea based on common factor method. This has a great advantage for applications that require higher speed.

In this thesis we improve and extend an algebraic technique pioneered by M. Gaudin. The technique is based on an infinite dimensional Lie algebra and a related family of mutually commuting Hamiltonians. In order to find energy eigenvalues of such Hamiltonians one has to solve the equations of Bethe ansatz. However, in most cases analytical solutions are not available. In this study we examine a special case for which analytical solutions of Bethe ansatz equations are not needed. Instead, some special properties of these equations are utilized to evaluate the energy eigenvalues. We use this method to find exact expressions for the energy eigenvalues of a class of interacting boson models. In addition to that, we also introduce a q-deformation of the algebra of Gaudin. This deformation leads us to another family of mutually commuting Hamiltonians which we diagonalize using algebraic Bethe ansatz technique. The motivation for this deformation comes from a relationship between Gaudin algebra and a spin extension of the integrable model of F. Calogero. Observing this relation, we then consider a well known periodic version of Calogero&#039 / s model which is due to B. Sutherland. The search for a Gaudin-like algebraic structure which is in a similar relationship with the spin extension of Sutherland&#039 / s model naturally leads to the above mentioned q-deformation of Gaudin algebra. The deformation parameter q and the periodicity d of the Sutherland model are related by the formula q=i{pi}/d.

Made available in DSpace on 2015-03-26T13:45:33Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1007963 bytes, checksum: 8fb51039076c92104d50598359cf19d8 (MD5) Previous issue date: 2011-02-24 / This work has as main objective the study of side-pairing patterns for hyperbolic polygons with 12g−6 edges and angles 2π/3 generated by trivalent graphs, in the case when the quotient of the hyperbolic plane by a Fuchsian group Γ (generated by the side-pairing of the polygon), H2/Γ , is a closed surface of genus g, g ≥ 2. So we did a study in case of g = 2, based on [10] and for the case of g = 3, based on [17]. In this work, we deduce two ways to get closed paths in the trivalent graphs cited in [10] and [17] and we contribute with exemples and results for cases of g > 3. Moreover, we find generalizations for some of these side-pairing patterns. / Este trabalho tem como objetivo principal o estudo de emparelhamentos de arestas para polígonos hiperbólicos com 12g − 6 arestas e ângulos iguais a 2π/3 gerados por meio de grafos trivalentes, no caso em que o quociente do plano hiperbólico por um grupo Fuchsiano Γ (gerado pelo emparelhamento do polígono), H2/Γ , é uma superfície fechada de gênero g, g ≥ 2. Assim, fizemos um estudo para o caso de g = 2 baseado em [10] e para o caso de g = 3, baseado em [17]. Neste trabalho, nós deduzimos duas formas de obter os caminhos fechados nos grafos trivalentes citados em [10] e [17] e contribuímos com exemplos e resultados para casos em que g > 3. Além disso, encontramos generalizações para alguns desses emparelhamentos de arestas.

Ce travail de thèse porte sur les propriétés de stabilité des tourbillons hélicoïdaux, structures que l'on retrouve notamment dans le sillage des rotors d'hélicoptères et d'éoliennes.Dans une première partie, le développement spatio-temporel de l'instabilité d'appariement est caractérisé à l'aide d'un code numérique pseudo-spectral pour une allée infinie d'anneaux tourbillonnaires. On montre que ce modèle axisymétrique d'écoulement est en effet une bonne approximation du système hélicoïdal dans la limite des grands rayons et petits pas d’hélice. Dans ces conditions, et en utilisant un adimensionnement judicieux, on obtient également que le résultat théorique pour le taux de croissance spatio-temporel obtenu pour une double allée de tourbillons ponctuels s’avère être une bonne prédiction pour le cas hélicoïdal.Dans une seconde partie, on décrit comment un ou plusieurs tourbillons hélicoïdaux ont pu être générés de façon très peu perturbée à l’aide de modèles réduits de rotors dans le canal hydrodynamique du laboratoire. Grâce à l’introduction de perturbations d’amplitudes et de fréquences soigneusement contrôlées, le taux de croissance de l’instabilité d’appariement a pu être mesuré et comparé aux résultats théoriques. L’évolution non linéaire de ces perturbations ainsi que d’autres modes instables, à plus petites longueurs d’onde, ont également pu être observés expérimentalement pour la première fois.Enfin, ces résultats ont été appliqués au cas des rotors d’hélicoptères pour la prédiction du régime de Vortex Ring State (VRS) et à la transition vers la turbulence du sillage des éoliennes. / This thesis is devoted to the stability properties of helical vortices, which are of interest for applications such as helicopter and wind turbine wakes.In a first part, the spatio-temporal development of the pairing instability is characterised for an infinite array of vortex rings, using a pseudo-spectral numerical code. We show that this axisymmetric flow model is indeed a good approximation of the helical system in the limit of large helix radius and small pitch. Under these assumptions, and by using appropriate dimensionless variables, we also show that the theoretical result concerning the spatio-temporal growth rate for a double row of point vortices represents a good prediction for the helical case.In a second part, we describe how one or several helical vortices were generated in a carefully controlled way using small-scale rotor models in the water channel of the laboratory. Introducing perturbations with well-defined amplitudes and frequencies, the growth rate of the pairing instability could be measured experimentally and compared to theoretical predictions. The non-linear evolution of these perturbations, as well as other unstable modes of smaller wavelengths, were also observed experimentally for the first time.Finally, these results were applied to helicopter wakes for the prediction of the Vortex Ring State (VRS) regime and to the transition to turbulence in wind turbine wakes.

Ces travaux de thèse se concentrent sur l'étude des attaques par canaux cachés et les implications sur les mesures à prendre pour un concepteur de circuits sécurisés. Nous nous intéressons d'abord aux différentes attaques par canaux cachés en proposant une amélioration pour un type d'attaque générique particulièrement intéressante : l'attaque par analyse d'information mutuelle. Nous étudions l'effet des différentes techniques d'estimation d'entropie sur les résultats de l'attaque. Nous proposons l'utilisation de fonctions B-splines comme estimateurs étant donné qu'elles sont bien adaptées à notre scénario d'attaques par canaux cachés. Nous étudions aussi l'impact que peut avoir ce type d'attaques sur un cryptosystème symétrique connu, l'Advanced Encryption Standard (AES), en proposant une contre-mesure basée sur la structure algébrique de l'AES. L'opération principale de la majorité des systèmes ECC est la multiplication scalaire qui consiste à additionner un certain nombre de fois un point de courbe elliptique avec lui-même. Dans une deuxième partie, nous nous intéressons à la sécurisation de cette opération. Nous proposons un algorithme de multiplication scalaire à la fois efficace et résistant face aux principales attaques par canaux cachés. Nous étudions enfin les couplages, une construction mathématique basée sur les courbes elliptiques, qui possède des propriétés intéressantes pour la création de nouveaux protocoles cryptographiques. Nous évaluons finalement la résistance aux attaques par canaux cachés de ces constructions. / This thesis focuses on the study of side-channel attacks as well as their consequences on the secure implementation of cryptographic algorithms. We first analyze different side-channel attacks and we propose an improvement of a particularly interesting generic attack: the mutual information analysis. We study the effect of state of the art entropy estimation techniques on the results of the attack. We propose the use of B-spline funtions as estimators as they are well suited to the side-channel attack scenario. We also investigate the consequences of this kind of attack on a well known symmetric cryptosystem, the Advanced Encryption Standard (AES), and we propose a countermeasure based on the algebraic structure of AES. The main operation of ECC is the scalar multiplication that consists of adding an elliptic curve point to itself a certain number of times. In the second part, we investigate how to secure this operation. We propose a scalar multiplication algorithm that is both efficient and secure against main side-channel attacks. We then study pairings, a mathematical construction based on elliptic curves. Pairings have many interesting properties that allow the creation of new cryptographic protocols. We finally evaluate the side-channel resistance of pairings.

Disertační práce se zabývá kryptografickými protokoly poskytující ochranu soukromí, které jsou určeny pro zabezpečení komunikačních a informačních systémů tvořících heterogenní sítě. Práce se zaměřuje především na možnosti využití nekonvenčních kryptografických prostředků, které poskytují rozšířené bezpečnostní požadavky, jako je například ochrana soukromí uživatelů komunikačního systému. V práci je stanovena výpočetní náročnost kryptografických a matematických primitiv na různých zařízeních, které se podílí na zabezpečení heterogenní sítě. Hlavní cíle práce se zaměřují na návrh pokročilých kryptografických protokolů poskytujících ochranu soukromí. V práci jsou navrženy celkově tři protokoly, které využívají skupinových podpisů založených na bilineárním párování pro zajištění ochrany soukromí uživatelů. Tyto navržené protokoly zajišťují ochranu soukromí a nepopiratelnost po celou dobu datové komunikace spolu s autentizací a integritou přenášených zpráv. Pro navýšení výkonnosti navržených protokolů je využito optimalizačních technik, např. dávkového ověřování, tak aby protokoly byly praktické i pro heterogenní sítě.