Modern embedded systems complexity, performance and energy efficiency has been increasing steeply the last few years. An explosive growth in demand for wireless communication is observed as well and modern wireless links are expected to deliver bit rates of several gigabits while consuming even less energy. In order to satisfy these needs new technologies emerge and novel design approaches are put into practice. Communication at 60 GHz is such a technology that is able to deliver high bit rates in short range wireless links. A major motivation to use the 60 GHz spectrum is the worldwide availability which makes exploitation economically viable. Moreover, small wavelength of only 5 mm promises high integration due to small antenna component size which is one of the main bottlenecks for reducing the dimensions. However, increased frequency comes with many disadvantages as well. To increase the market potential of such a new technology the chip design needs to be cheap and energy-efficient. Such cost and energy constrains heavily impact the performance and the quality of both the analog and the digital components of the chip. In the current thesis the design possibilities of a component in the digital baseband of the receiver of such a chip are explored. The component under investigation is a Fast Fourier Transform (FFT) that is used for frequency domain equalization. This part of the receiver is used to reduce the effects of multipath in a non line-ofsight communication environment and as this is a common case in wireless communication the FFT block has been identified as one of the 2 most computational intensive components of the receiver in 60 GHz. This is the main reason why we explore possibilities to further decrease the power consumption of the block while maintaining the performance and the quality of service. To achieve this reduction the possibilities of a new design concept are explored. System Scenarios is a new design concept for embedded systems operating in dynamic environments. Wireless communication systems exhibit high dynamism during their operation on highly varying data streams, providing the System Scenarios huge xvi capabilities. The essential idea behind system scenarios is the classification of the application under investigation from a cost perspective during design time. Then, the classification is exploited during run time resulting to an overall improved implementation of the application. To achieve this the application is broken down to run-time situations (RTS) which are distinguishable operation modes of the application. Then RTSs with similar costs are clustered to form system scenarios. Finally for each scenario a different mapping and scheduling of the application is generated. In the case of the current thesis the application is the FFT and the cost perspective is the power consumption of the component. To exploit the RTS clustering in run time different quantization schemes have been produced. These schemes have been generated based on various properties of the data waveforms in the input of the FFT. The thesis explores the potential of the System Scenarios as well as the application of a quantization methodology for the FFT. Different options of the RTS clustering and the quantization of the FFT block are evaluated in order to come up with a more efficient implementation. / Τα σύγχρονα ηλεκτρονικά συστήματα παρέχουν στους χρήστες έναν καθημερινά αυξανόμενο αριθμό υπηρεσιών και λειτουργιών. Η ζήτηση τς αγοράς για ϕθηνές, αξιόπιστες και ϕορητές ηλεκτρονικές συ- σκευές ωθεί τα όρια του σχεδιασμού των ενσωματωμένων συστημάτων σε νέες ανεξερεύνητες περιοχές. Η ϕορητότητα απαιτεί την αϕαίρεση όλων των καλωδίων είτε για μετάδοση δεδομένων είτε για ενέργεια. Για να επιτευχθεί αυτό, η ασύρματη επικοινωνία σε υψηλό ρυθμό μετάδοσης είναι επιθυμητή χωρίς να θυσιαστεί η υψηλή ενεργειακή απο- δοτικότητα που καθιστά την συσκευή αυτόνομη από το ενεργειακό δίκτυο για μεγάλες χρονικές περιόδους. Η συνεχής αύξηση στις προδιαγραϕές των σύγχρονων ενσωματομένων συστημάτων έχει οδηγήσει στην χρήση καινοτόμων ιδεών, προσεγγίσεων και τεχνολογιών. Μια νέα τεχνολογία που υπόσχεται υψηλή ολοκλήρωση και υψηλό ρυθμό μετάδοσης δεδομένων στις ασύρματες ζεύξεις είναι η επικοινωνία στα 60 GHz. Μια νέα προσέγγιση σχεδιασμού για ενσωματομένα συστήματα υπόσχεται αποτελεσματική εκμετάλευση του δυναμισμού που μπορεί να παρουσιάζει ένα σύστημα. Τα ασύρματα συστήματα επικοινωνίας λειτουργούν τυπικά σε πολύ δυναμικά περιβάλλοντα. Τα Σενάρια συστήματος έχουν μεγάλες δυνατότητες για να βελτιώσουν την αποτελεσματικότητα της υλοποίησης των ψηϕιακών βάσεων τέτοιων συστημάτων. Στην παρούσα διπλωματική εξερευνούμε της δυνατότητες της αρχιτεκτονικής του FFT που βρίσκεται στην πλευρά του δέκτη ενός πομποδέκτη στα 60 GHz. Ο FFT είναι μέρος της εξίσωσης στο πεδίο της συχνότητας που χρησιμοποιείται για να μειώσει της επιδράσεις του ϕαινομένου multipath. Χρησιμοποιώντας Σενάρια Συστήματος προσπαθούμε να καταλήξουμε με μια πιο προσαρμοστική και συνεπώς πιο ενεργειακά αποδοτική υλοποίηση του μετασχηματισμού. Η εϕαρμογή των Σεναρίων Συστήματος χρησιμοποιώντας δεδομένα ως παράμετρο είναι μια καινοτόμα προσέγγιση και σε αυτή την διπλωματική εργασία ελέγχουμε την επιτευξιμότητα της. Για να επιτύχουμε κάτι τέτοιο πρέπει να μπορούμε να παράγουμε πολλαπλά διαϕορετικά σχέδια κβαντοποίησης του μετασχηματισμού σε αποδεκτά χρονικά διαστήματα. Οι παρούσες μέθοδοι κβαντοποίησης δεν μπορούν ακόμα να παρέχουν τέτοια δυνατότητα. Έτσι βασιζόμενοι στην επέκταση μια υπάρχουσας μεθοδολογίας προτείνουμε μια ολοκληρωμένη μεθοδολογία που μπορεί να παράγει σχέδια κβαντοποίησης μεγάλων στοιχείων υλικού όπως ο FFT.

Στο πεδίο των ασύρματων επικοινωνιών της τάξης των 60 GHz που αντιστοιχούν σε ρυθμούς μετάδοσης multi-gigabits ανά δευτερόλεπτο, οι σύγχρονες υλοποιήσεις βασίζονται στα ιδιαίτερα προσαρμοζόμενα ASICs, ανάλογα με τις ανάγκες της εφαρμογής. Απαιτούνται γενικώς υψηλές ταχύτητες επεξεργασίας σε συνδυασμό με χαμηλή κατανάλωση ενέργειας. Ωστόσο, για να υποστηριχθούν διαφορετικά πρότυπα με μεγάλη διαφοροποίηση τρόπων χρήσης, είναι ιδιαίτερα επιθυμητές λύσεις αρχιτεκτονικής που μπορούν να προγραμματιστούν και να ρυθμιστούν έτσι ώστε αυξάνοντας το δυνατό αγοραστικό κοινό, να μειωθεί το κόστος επεξεργασίας ανά chip. Στις μέρες μας, τα ASIPs (Application-Specific Instruction-set Processors) δεν είναι εφικτά λόγων των υψηλότατων απαιτήσεων απόδοσης/ενέργειας. Ωστόσο, το κενό που υπάρχει με τα ASICs μπορεί κατά μεγάλο μέρος να γεφυρωθεί ή και να εξαλειφθεί, εισάγοντας και χρησιμοποιώντας ποιο δυναμική συμπεριφορά στην ψηφιακή front-end λειτουργικότητα. Για να επιτευχθεί αυτό, απαιτούνται καινοτομίες στην πλευρά της αρχιτεκτονικής του επεξεργαστή και ειδικότερα στον τρόπο που οι αλγόριθμοι αντιστοιχίζονται σε αυτές τις απαιτήσεις. Ξεκινώντας από παλαιότερα πειράματα που έδειξαν ότι η ιδέα αυτή είναι εφικτή, τα αντιπροσωπευτικά αλγοριθμικά τμήματα (με βάση κυρίως τον FFT) θα αντιστοιχηθούν στην επιλεγμένη αρχιτεκτονική ASIP για εφαρμογές στα 60 GHz. Σε αυτά τα πλαίσια, θα εφαρμοστεί η μεθοδολογία του διαγράμματος ροής εκτιμήσεων υψηλής κλίμακας (high level estimations flowchart). Πιο συγκεκριμένα, αρχικά θα αποκτηθεί μια πιο ακριβής καταγραφή του λειτουργικού κόστους της αλυσίδας φορτίου δεδομένων του ψηφιακού μέρους του δέκτη που υλοποιεί το πρότυπο επικοινωνιών στα 60 GHz. Στη συνέχεια θα κβαντιστούν οι πιο πολύπλοκοι, λειτουργικά, πυρήνες της αλυσίδας, όπως θα προκύψει από το προηγούμενο βήμα και τελικά οι πυρήνες αυτοί θα αντιστοιχηθούν σε αναδιαμορφώσιμα αρχιτεκτονικά μοντέλα. Η εργασία θα επικεντρωθεί στον FFT, που αναμένεται να έχει τη μέγιστη λειτουργική πολυπλοκότητα και θα προταθεί μια διαφορετική προσέγγιση για τον τρόπο προσπέλασης των δεδομένων και των συντελεστών στην SRAM και το register file, με στόχο την ελάττωση της κατανάλωσης ενέργειας του πυρήνα αυτού. Τέλος, θα παρατεθεί μια συγκριτική μελέτη των σχημάτων πρόσβασης που θα ερευνηθούν. Με αυτόν τον τρόπο μπορούν να ποσοτικοποιηθούν τα συνολικά κέρδη της έρευνάς μας. / In the domain of multi-gigabits per second wireless 60 GHz communication transceivers and beyond, today's implementations are all based on heavily customized application-specific integrated circuits (ASICs). The basic motivation for this customization is the extremely high processing speeds that are required, in combination with the need for low energy consumption. However, to support different standards and highly varying usage modes, more programmable or configurable architecture solutions are strongly desirable to increase the potential market volume and in this way to reduce the per-chip processing costs. Today these application-specific instruction set processors or ASIPs are not feasible due to the too high performance/energy requirements. Nevertheless, we believe that by introducing and exploiting more dynamic behavior in the digital front-end functionality, the performance/energy gap with the ASICs can be largely bridged and potentially even fully overcome. In order to achieve this, innovations are required on the processor architecture side and especially on the way algorithms are mapped to those architectures. In this thesis, we will start from earlier experiments which have shown the viability of the above concept. Τhe representative algorithmic blocks (mainly FFT oriented) will be mapped onto reconfigurable hardware based on ASIP architectures for 60 GHz applications. In this way we can quantify the overall gains and check how far the approach can be extended to exploit all the available dynamism using the concept of scenario clustering. In this context, we will follow the steps of the high level estimations flowchart methodology. In particular, we will obtain a more accurate account of the operational complexity of the digital base-band payload chain kernels, quantize the most complex of them and then map them in reconfigurable architectures. Especially for the FFT kernel, that is expected to show the highest complexity, we will implement a different approach in the accessing of the data and coefficients that intends to limit the energy usage of the kernel. For this purpose, we will end this work with a comparative study of different schemes explored.

The increasing number of portable devices, such as Smart phones, laptops, tablets etc, has certainly pushed up the market of wireless communication systems. These high performance devices need to comply with the strict requirements in terms of energy consumption. Battery capacity progress is relatively slower compared with the technological evolution of devices. Therefore, energy consumption issues can be solved when innovations are introduced in the processor design and architecture side. This thesis focuses on the word-length optimization for algorithms that run on wireless receivers with multiple antennas (MIMO). The study was made for the signal’s quantization. Earlier experiments have shown that the signal conversion from floating–point to fixed–point representation requires unaffordable Bit-Error-Rate (BER) simulations that may last for hours or even for days. During this thesis, a new divide-and-conquer method has been developed. It faces the ‘quantization problem’ hierarchically by grouping signals and exploiting the correlation between quantization error and Gaussian additive noise. BER simulations were limited by involving noise simulations. This method was successfully applied to a highly adaptive digital signal processing (DSP) algorithm, improving the total simulation time up to 84%. / Η αυξανόμενος αριθμός των κινητών συσκευών, όπως τα Smart phones, laptops, tablets κλπ, έχει εκτοξεύσει υψηλά την αγορά των ασύρματων συσκευών επικοινωνίας. Αυτές οι συσκευές υψηλής τεχνολογίας πρέπει να συμμορφώνονται με τις αυστηρές απαιτήσεις στα πλαίσια της κατανάλωσης ενέργειας. Η πρόοδος της αύξησης της χωρητικότητας της μπαταρίας χαρακτηρίζεται σχετικά αργή συγκρινόμενη με την τεχνολογική εξέλιξη των συσκευών. Ως εκ τούτου, θέματα που αφορούν στην κατανάλωση ενέργειας αντιμετωπίζονται όταν πραγματοποιούνται καινοτομίες στον τομέα της σχεδίασης και αρχιτεκτονικής επεξεργαστών. Η παρούσα διατριβή εστιάζει στην βελτιστοποίηση των μηκών λέξεων (word-length optimization) για αλγορίθμους που τρέχουν σε ασύρματους δέκτες με πολλαπλές κεραίες (MIMO). Η μελέτη αφορά στην κβαντοποίηση σημάτων (signal quantization). Προηγούμενα πειράματα έδειξαν ότι η μετατροπή των σημάτων άπειρης ακρίβειας (floating-point) σε πεπερασμένης (fixed-point) απαιτεί χρονοβόρες Bit-Error-Rate (BER) προσομοιώσεις που μπορεί να διαρκέσουν πολλές ώρες ή ακόμη και ημέρες. Κατά την διάρκεια της διπλωματικής εργασίας, αναπτύχθηκε μία νέα divide-and-conquer μέθοδος. Αντιμετωπίζει το πρόβλημα της κβαντοποίησης ιεραρχικά ομαδοποιώντας τα σήματα και εκμεταλλεύοντας την συσχέτιση του σφάλματος κβαντοποίσης (quantization error) και του προσθετικού Γκαουσιανού θορύβου (AWGN). Οι BER προσoμοιώσεις περιορίστηκαν περιλαμβάνοντας προσομοιώσεις θορύβου (noise simulations). Αυτή η μέθοδος εφαρμόστηκε επιτυχώς σε πολύπλοκο αλγόριθμο υψηλής προσαρμοστικότητας για DSP, βελτιώνοντας τον συνολικό χρόνο προσομοίωσης έως και 84%.

No description available.

Postulamos una estructura sintáctica unitaria para las construcciones con verbos parasintéticos de los tipos a-…-ar y en-…-ar mediante cuatro hipótesis: ambos esquemas verbales tienen una estructura sintáctica básica común en relación con Sv y SV, cuyos núcleos son CAUSE y BECOME, respectivamente; la diferencia entre ambos radica en que, dentro de la escala de afectación (Beavers 2011), en relación con a-…-ar, se especifica (composicionalmente) el estado resultante del tema, mientras que, en relación con en-…-ar, ello no tiene lugar. Proponemos que la afectación es un operador ubicado en una proyección externa a Sv, el cual cuantiza el evento determinando la especificidad del estado resultante para el objeto;y la forma morfológica del operador es a- o en- en caso de que su valor seapositivo o negativo respectivamente. / I postulate an unitary syntactic structure for constructions with a-…-ar and en-…-ar parasynthetic verbs through four hypothesis: both patterns have a common basic syntactic structure regarding vP and VP, whose heads are CAUSE and BECOME,  respectively; the difference between the patterns lies on, within a scale of affectedness (Beavers 2011), the fact that a-…-ar assigns (compositionally) a result state to the theme, while this does not happen with en-…-ar. I claim that affectedness is a binary operator located higher than vP that quantizes the event determining the specificity of the result state for the object; and the morphological form of the operator is a- (if its value is positive) or en- (if its value is negative).

SOUZA, Francisco Emmanoel Andrade de. Superpartícula de Brink-Schwarz. 2015. 41 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-04-09T19:14:41Z No. of bitstreams: 1 2015_dis_feasouza.pdf: 334413 bytes, checksum: 0cdd802691e14a640eef8c0a3aa12b7c (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-04-10T20:46:16Z (GMT) No. of bitstreams: 1 2015_dis_feasouza.pdf: 334413 bytes, checksum: 0cdd802691e14a640eef8c0a3aa12b7c (MD5) / Made available in DSpace on 2015-04-10T20:46:16Z (GMT). No. of bitstreams: 1 2015_dis_feasouza.pdf: 334413 bytes, checksum: 0cdd802691e14a640eef8c0a3aa12b7c (MD5) Previous issue date: 2015 / In this work, the pseudo-classical formulation of relativistic and non-relativistic Brinck-Schwarz superparticle is presented. Such a formulation has a portion represented by Grassmann variables that describe the degrees of freedom of spin. During the formulation of the theory, we use the theory of constraints to allow quantization of the system and also we constructed a Lagrangian representing Grassmannian systems. Such a system is invariant under supersymmetry and reparameterizations. The Dirac equation appears as a constrainst of theory. / Neste trabalho, a formulação pseudo-clássica da superpartícula de Brinck-Schwarz relativística e não-relativística é apresentada. Tal formulação possui uma parte representada por variáveis de Grassmann que descrevem os graus de liberdade de spin. Durante a formulação da teoria, utilizou-se a teoria dos vínculos para possibilitar a quantização do sistema e foi construída também uma Lagrangeana que represente sistemas Grassmannianos. Tal sistema é invariante sob supersimetria e reparametrização. A equação de Dirac surge como um vínculo da teoria.

Massive multiple-input multiple-output is a promising technique for the next generation of wireless communication systems which addresses most of the critical challenges associated with concurrent relaying systems, such as digital signal processing complexity, long processing delay, and low latency wireless communications. However, the deployment of conventional fully digital beamforming methods, dedicates one radio frequency (RF) chain to each antenna, is not viable enough due to the high fabrication/implementation cost and power consumption. In this thesis, we envision to address this critical issue by reducing the number of RF chains in a viable analog/digital configuration paradigm which is usually referred to hybrid structure. From another viewpoint, the development of fifth generation enabling technologies brings new challenges to the design of power amplifiers (PAs). In particular, there is a strong demand for low-cost, nonlinear PAs which, however, introduce nonlinear distortions. On the other hand, contemporary expensive PAs show great power efficiency in their nonlinear region. Inspired by this trade-off between nonlinearity distortions and efficiency, finding an optimal operating point is highly desirable, and this is the second key contribution of this thesis.

Submitted by Anderson Nogueira (andsogueira@hotmail.com) on 2016-03-08T21:06:11Z No. of bitstreams: 1 Tese-Anderson.pdf: 1337697 bytes, checksum: 95996aacf55769a399e7a2c11a2a1e5f (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-09T18:28:05Z (GMT) No. of bitstreams: 1 nogueira_aa_dr_ift.pdf: 1337697 bytes, checksum: 95996aacf55769a399e7a2c11a2a1e5f (MD5) / Made available in DSpace on 2016-03-09T18:28:05Z (GMT). No. of bitstreams: 1 nogueira_aa_dr_ift.pdf: 1337697 bytes, checksum: 95996aacf55769a399e7a2c11a2a1e5f (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho tem como objetivo explorar a dinâmica quântica de interação entre partículas escalares e vetoriais e estudar o equilíbrio termodinâmico dessas partículas no ensemble gran-canônico. A dinâmica de interação, escrita em uma linguagem covariante entre o campo de matéria (escalar) e o campo intermediador de interação (vetorial), apresenta uma simetria de calibre local, U(1) no caso quântico e SO(4) no equilíbrio termodinâmico. Sendo assim dividimos o trabalho em dois setores. No primeiro setor analisamos sistematicamente a interação quântica entre partículas escalares (mésons) e partículas vetoriais (fótons) no contexto da eletrodinâmica quântica escalar generalizada de Duffin-Kemmer-Petiau (GSDKP). Para isso quantizamos a teoria, utilizando uma abordagem funcional. Construímos a estrutura Hamiltoniana do sistema seguindo a metodologia de Dirac, o procedimento de Faddeev-Senjanovic para obter a amplitude de transição no calibre de Coulomb generalizado e o método de Faddeev-Popov-DeWitt para escrever a amplitude de transição anterior de maneira covariante na condição de calibre no-mixing. Daí, escrevendo o funcional gerador via Schwinger, as equações de Schwinger-Dyson (SD) e as identidades de Ward-Takahashi (WT) são obtidas. Como introdução à análise das correções radiativas, fizemos um cálculo quantitativo para ver os tipos de divergências superficiais (ultravioleta) que poderiam aparecer na teoria. Depois apresentamos um cálculo explícito das primeiras correções radiativas (1-laço) associadas ao propagador do fóton, propagador do méson, vértice e, estudamos a função de 4 pontos (fóton-fóton) utilizando o método de regularização dimensional, em que a simetria de calibre é manifesta. Como veremos, uma consequência do estudo é que a álgebra de DKP assegura o funcionamento das identidades de WT nas primeiras correções radiativas proibindo certas divergências no ultravioleta. Com o conhecimento das divergências no ultravioleta (UV) e no infravermelho (IV) abordadas nas correções radiativas, estabelecemos o Programa de Renormalização multiplicativo para esta teoria na camada de massa. O fato do propagador do campo escalar possuir uma nova estrutura divergente na massa de Podolsky nos levou a analisar as correções radiativas a 2-laços. Do propagador do fóton definimos o tensor de polarização e com este, de maneira fenomenológica, analisando o comportamento assintótico das funções de Green para altos momentos, abordamos a dependência da constante de estrutura com a escala de energia. No segundo setor estudamos o Formalismo de Matsubara-Fradkin (MF) para descrever campos em equilíbrio termodinâmico. Para isso foi necessário construir as equações em equilíbrio termodinâmico que descrevessem o setor escalar e vetorial e a posteriori extrair a função de partição. Ao construir o setor vetorial, percebemos o surgimento e a importância dos campos fantasmas e sua conexão com a simetria de Bechi-Rouet-Stora-Tyutin (BRST). No caso da escolha de calibre covariante no-mixing, foi necessário contornar o surgimento de uma estrutura pseudo-diferencial. Analisando a função de partição associada aos fótons livres de Podolsky via método dos parâmetros fictícios, percebemos o fato da simetria BRST assegurar que a função de partição não depende das escolhas covariantes ao fixarmos o calibre. As condições de Lorenz, no-mixing e Lorenz generalizado são amarradas pela simetria BRST e esse fato está contido em uma afirmação geral em teorias de calibre a temperatura finita, atribuída ao trabalho de Tyutin, de que a física não depende das escolhas de calibre, covariantes ou não, devido a simetria BRST. Por fim, com a funções de partição em mãos, construímos as equações de Schwinger-Dyson-Fradkin (SDF) e as identidades de Ward-Takahashi-Fradkin (WTF) em equilíbrio termodinâmico. / This work has as aim to explore the quantum dynamics of interaction between scalar and vectorial particles and to study the thermodynamic equilibrium of these particles in the gran-canonical ensemble. The dynamics of interaction, written in a covariance language, between the matter field (scalar) and the field that intermediate the interaction (vectorial) exhibit a local gauge symmetry, U(1) in a quantum case and SO(4) in a thermodynamic equilibrium. Therefore we divided the work into two sections. In the first section we analyze systematically the quantum interaction between the scalar particles (mesons) and vectorial particles (photons) in the context of the generalized scalar Duffin-Kemmer-Petiau quantum electrodynamics (GSDKP). For this we use the functional approach to quantize the theory. We built the hamiltonian structure by the Dirac methodology, utilize the Faddeev-Senjanovic procedure to obtain the transition amplitude in the generalized Coulomb gauge and the Faadeev-Popov-DeWitt method to write the covariant form of the previously amplitude in the no-mixing gauge condition. Then writing the functional generator by Schwinger, the Schwinger-Dyson (SD) equations and the Ward-Takahashi (WT) identities are obtained. As an introductory analysis to the first radiative corrections we make a quantitative calculus to see the types of ultraviolet (UV) superficial divergences that appear in the theory. After this we show an explicit calculation of the first radiative corrections (1-loop) associated with the photon propagator, meson propagator, vertex and the 4 point function (photon-photon) utilizing the dimensional regularization method, where the gauge symmetry is manifest. As we will see one of the consequences of the study is that the DKP algebra ensures the functioning of the WT identities in the first radiative corrections prohibiting certain UV divergences. With the knowledge of the UV divergences and de infrared (IR) addressed in the radiative corrections we established the multiplicative renormalization procedure to this theory in the mass shell. The fact that the meson propagator has a new divergence structure in terms of the Podolsky mass took us to analyze the radiative correction at 2-loops. With the photon propagator we define the polarization tensor and in a phenomenological manner, analyzing the asymptotic behavior of Green's functions for higher momentum, we derive the dependence of the structure constant by the scale of energy. In the second section we study the Matsubara-Fradkin (MF) formalism to describe fields in thermodynamical equilibrium. For this it was necessary to construct the equations in thermodynamic equilibrium that describe the scalar sector and vectorial sector and then extract the partition function. When we construct the vectorial sector we realize the emergence and the importance of the ghost fields and their connection to the Bechi-Rouet-Stora-Tyutin (BRST) symmetry. In the case of the no-mixing gauge condition was necessary to contour a pseudo-differential structure. Analyzing the free partition function associated with the free Podolsky photons by the method of fictitious parameters we realize that the BRST symmetry ensures that it does not depend of the covariant choices when we fix de gauge. The Lorenz condition, no-mixing and generalized Lorenz are tied by the BRST symmetry and this fact is contained in a general statement in gauge theories at finite temperature, assigned by Tyutin work, that the physics doesn't depend of the gauge choices, covariant or not, due to BRST symmetry. Lastly, with the partition function in hands, we construct the Schwinger-Dyson-Fradkin (SDF) and the Ward-Takahashi-Fradkin (WTF) in thermodynamic equilibrium.

Made available in DSpace on 2014-06-11T19:32:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-06Bitstream added on 2014-06-13T19:47:10Z : No. of bitstreams: 1 echevarria_cat_me_ift.pdf: 657711 bytes, checksum: d365934122a9e19d3c69fab3a408cda4 (MD5) / Primeiramente apresenta-se uma breve descrição das teorias de primeira quantização covariante da corda bosônica, supercorda RNS e GS. Também apresentamos a descrição topológica da supercorda. Em seguida , fazemos uma introdução à teoria clássica de campos da corda bosônica aberta formulado por Witten. Depois, consideramos a toeria clássica de campo de supercorda aberta que usa as variáveis RNS. Discutimos o problema da divergência que surge em termos de contato relacionados com picture. O formalismo topológico permite construir uma ação para teoria de campos de supercorda que é do tipo WZW. Esta ação resolve o problema da divergência. Este fato é verificado com cálculo explícito da amplitude de espalhamento para quatro estados externos na camada da massa. Seguidamente, discutimos as branas não BPS, condensação do táquion e construimos os vértices com projeção GSO negativo para o táquion e o férmion não massivo usando variáveis híbridas. Finalmente incluimos o setor GSO (-) da supercorda numa ação generalizada do tipo WZW. / Firstly we present a brief description of the covariant first quantized theories of string, RNS and GS superstring. Also we present a topological description of the superstring. Then we give an introduction to the classical open string field theory formulated by Witten. After that we cosnider the classical open superstring field theory using the RNS variables, we discuss the problem of the divergence that appears in contact terms that is related with picture. The topological formalism allow us to construct an action for the open superstring field theory which is WZW-like. This action solves the divergence problem, and we verify this fact by explicit computation of the scttering amplitude for four external on-shell states. Next, we discuss nonBPS D-branes, tachyon condensation and construct the GSO negative projected vertices for the tachyona and the massless fermion using hybrid variables. Finally we include the GSO (-) sector of the superstring in a generalized WZW-like action.

L'essor des nouvelles technologies de télécommunication et de conception des capteurs a fait apparaître un nouveau domaine du traitement du signal : les réseaux de capteurs. Une application clé de ce nouveau domaine est l'estimation à distance : les capteurs acquièrent de l'information et la transmettent à un point distant où l'estimation est faite. Pour relever les nouveaux défis apportés par cette nouvelle approche (contraintes d'énergie, de bande et de complexité), la quantification des mesures est une solution. Ce contexte nous amène à étudier l'estimation à partir de mesures quantifiées. Nous nous concentrons principalement sur le problème d'estimation d'un paramètre de centrage scalaire. Le paramètre est considéré soit constant, soit variable dans le temps et modélisé par un processus de Wiener lent. Nous présentons des algorithmes d'estimation pour résoudre ce problème et, en se basant sur l'analyse de performance, nous montrons l'importance de l'adaptativité de la dynamique de quantification pour l'obtention d'une performance optimale. Nous proposons un schéma adaptatif de faible complexité qui, conjointement, estime le paramètre et met à jour les seuils du quantifieur. L'estimateur atteint de cette façon la performance asymptotique optimale. Avec 4 ou 5 bits de résolution, nous montrons que la performance optimale pour la quantification uniforme est très proche des performances d'estimation à partir de mesures continues. Finalement, nous proposons une approche à haute résolution pour obtenir les seuils de quantification non-uniformes optimaux ainsi qu'une approximation analytique des performances d'estimation. / With recent advances in sensing and communication technology, sensor networks have emerged as a new field in signal processing. One of the applications of his new field is remote estimation, where the sensors gather information and send it to some distant point where estimation is carried out. For overcoming the new design challenges brought by this approach (constrained energy, bandwidth and complexity), quantization of the measurements can be considered. Based on this context, we study the problem of estimation based on quantized measurements. We focus mainly on the scalar location parameter estimation problem, the parameter is considered to be either constant or varying according to a slow Wiener process model. We present estimation algorithms to solve this problem and, based on performance analysis, we show the importance of quantizer range adaptiveness for obtaining optimal performance. We propose a low complexity adaptive scheme that jointly estimates the parameter and updates the quantizer thresholds, achieving in this way asymptotically optimal performance. With only 4 or 5 bits of resolution, the asymptotically optimal performance for uniform quantization is shown to be very close to the continuous measurement estimation performance. Finally, we propose a high resolution approach to obtain an approximation of the optimal nonuniform quantization thresholds for parameter estimation and also to obtain an analytical approximation of the estimation performance based on quantized measurements.