Dissertations / Theses on the topic 'Polar Form'

O estudo dos nÃmeros complexos no ensino mÃdio à caracterizado, quase exclusivamente, pela abordagem algÃbrica deixando a parte geomÃtrica e suas aplicaÃÃes sem uma devida importÃncia. Este trabalho apresenta um estudo sobre nÃmeros complexos bem como algumas de suas aplicaÃÃes tanto da parte algÃbrica, aplicada a polinÃmios, quanto da parte geomÃtrica aplicada em especial à trigonometria. De inÃcio fizemos uma abordagem dos fatos histÃricos desses nÃmeros citando alguns matemÃticos que deram suas contribuiÃÃes acerca desse conjunto complexo. Em seguida à apresentada a parte teÃrica, algÃbrica e geomÃtrica, bem como algumas aplicaÃÃes a trigonometria. Por fim apresentamos a teoria das equaÃÃes algÃbricas quadrÃticas e cÃbicas e a interaÃÃo dessas com os nÃmeros complexos.<br>The study of the complex numbers in the medium teaching is characterized, almost exclusively, for the algebraic approach leaving the geometric part and their applications without a due importance. This work presents a study on complex numbers as well as some of their applications so much of the algebraic part, applied to polynomials, as of the geometric part especially applied to the trigonometry. Of I begin did an approach of the historical facts of those numbers mentioning some mathematical that gave their contributions near of that complex group. Soon afterwards the part theoretical, algebraic and geometric is presented, as well as some applications the trigonometry. Finally we presented the theory of the quadratic and cubic algebraic equations and the interaction of those with the complex numbers.

The present work related to apply hot-melt ink-jet process for imaging at offset lithographic printing form, to utilise a reusable surface for many times and particularly related to validating thermal and ultrasonic erasing processes. This dissertation investigated systematically the role of certain factors towards affecting erasing image area process on print surfaces. Thermal erasing process approved to melt and suck the image area from the surface, the results were adopted by using contact angle measurements and scanning electron microscope. Ultrasonic erasing process permitted to solve the image area by choosing erasing chemistries, influence of selected erasing chemistries on printing surface, and evaluation the process, the results were tested by UV/Vis spectrometer, contact angle, profileometery and visual microscope<br>Der Fortschritt im Bereich von Charakterisierung und Verständnis für Hot-melt Ink Jet Prozesse zur Bebilderung von Offsetdruckform-Zylindern ist ein Ergebnis dieser Forschung. Die Systematik dieser Arbeit basiert auf einem theoretischen Teil, um einen geeigneten Löschprozess auszuwählen. Der Löschprozess hängt von den Eigenschaften des Hot-melt Ink Jet Materials und der genutzten Aluminiumdruckoberfläche ab. Diese werden systematisch im Labormaßstab experimentell untersucht. Der thermische Prozess wurde einerseits durch Benetzbarkeitsprüfungen und anderseites durch Rasterelektronmikroskopaufnahmen bewertet.Der Ultraschallprozess ist ein nasser Löschprozess. Die Untersuchungen wurden in vier Stufen systematisch durchgeführt - Auswahl vom geeigneten Lösungsmitteln - Einflüsse von ausgewählten Lösungsmitteln auf nicht beschichtete und beschichtete Aluminium platten - Evaluation eines Ultraschalllöschprozesses - Validation eines Löschprozesses; zur Bewertung des Löschprozesses wurden mehrere Druckplattenproben bebildert und gelöscht Die Ergebnisse wurden durch UV/Vis Spektrometer, Kontaktwinkel, Profiliometrie und Visuelle Mikroskopie getestet

In the past several decays, lattice codes played an important role in coding theory and information theory. Lattice codes with good performance in communication and source compression have attracted considerable interest. A typical method of constructing good lattice codes is to use existing linear codes. For instance, the famous Barnes-Wall lattices are generated by Reed-Muller (RM) codes, and more recently, the emerging low density Construction-A (LDA) lattices are resulted from low density parity check (LDPC) codes. In this thesis, we develop a new class of lattices, called polar lattices, based on polar codes. The invention of polar codes is considered to be one of the major breakthroughs in coding theory for the past ten years. We show that polar lattices provide explicit solutions for many interesting problems in information theory. For channel coding, we prove that polar lattices are capable of achieving the capacity of the additive white Gaussian noise (AWGN) channel. For the dual side, i.e., source compression, polar lattices can also achieve the rate-distortion bound for the independent and identically distributed (i.i.d.) Gaussian source. Moreover, a combining design of polar lattices for both channel coding and source coding gives us explicit solutions to the Gaussian version of the Wyner-Ziv and Gelfand-Pinsker problems. For physical layer security, we prove that polar lattices are able to approach the secrecy capacity of the Gaussian wiretap channel under the strong secrecy criterion. Two more applications of polar lattices are achieving the capacity of the i.i.d. fading channel and extracting the common information of two joint Gaussian sources. The explicit construction of polar lattices provides us better insights on the study of lattice coding. Many interesting problems of lattice coding, such as AWGN goodness, secrecy-goodness, lattice shaping, and lattice Gaussian distribution will be addressed from the perspective of polar lattices.

Identication systems are ubiquitous, for example, biometric identication systemswith ngerprints and Face IDs, etc. Basically, the identication problemconsists of two steps. The enrollment phase where the user's data are captured,compressed and stored, for example taking the ngerprint or capturing some importantfeatures of your face. In the identication phase, an observation, yourngerprint or your face, is compared with the stored information in the databaseto provide an armative answer. Since the system involves many users, bothstoring and searching for the correct user is challenging.This project aims to implement compression and identication algorithms forthe high dimensional identication system which includes M users. Polar codesare employed to be the main toolbox. Firstly, we implement polar codes for thesource compression and then design corresponding identication mappings. Thesource compression can be seen as the channel decoding of polar codes. In theidentication phase, the observation can be seen as the side information, so wewill consider using Wyner-Ziv coding for polar codes to reconstruct and identify.In the next step, we will implement polar codes for two-layer Wyner-Zivcoding for identication systems. This will enable us to store the compresseddata in separate databases and do the reconstruction in two stages. With theenrollment mapping and identication mapping implemented, we will evaluatethe performance of the designed identication systems, such as identicationerror rate and complexity. Some possible further directions would be to implementmore advanced algorithms such as simplied or fast simplied successivecancellation encoding in source coding and universal decoding in identication.<br>Identieringssystem frekommer verallt, till exempel, biometriska identieringssystemmed ngeravtryck och ansiktsigenknning, etc. Fundamentalt kan problemetbrytas ned i tv faser. Registreringsfasen dr data om anvndaren insamlas, komprimerasoch lagras, till exempel att ta ngeravtryck eller nna viktiga ansiktsdetaljer.I identieringsfasen, jmfrs en observation, ditt ngeravtryck elleransikte, med information som lagrats tidigare fr att ge ett positivt svar. Eftersomsystemet hanterar mnga anvndare r bde lagring och skning efter den rttaanvndaren utmanande.Syftet med detta projekt r att designa och implementera eektiva komprimeringsochidentieringsalgoritmer fr det hgdimensionella Identieringssystemet medM anvndare. Polar codes anvnds som det huvudsakliga verktyget. Frst implementerarvi polar codes fr eektiv kllkomprimering och designar sedan motsvarandeidentieringskartlggning. Kllkomprimering kan ses som kanalavkodningen avpolar codes och I identieringsfasen kan observationen ses som sido-informationen,s vi vervger att anvnda Wyner-Ziv kodning fr polar codes fr att rekonstrueraoch identiera. I nsta steg implementerar vi polar codes fr skra Wyner-Zivproblem. Detta tillter oss att spara komprimerad data i separata databaser ochterskapa med tv steg. Med registreringskarlggning och identieringskartlggningimplementerade utvrderar vi prestandan av de designade identieringssystemenmed metoder som felfrekvens av identieringar och berkningskomplexitet.

Traditional teaching methods are often passive and do not interactively engage students, and this is even more challenging when teaching programming to beginners. In recent years, tech companies such as Google, and academic institutions like MIT, have introduced online learning environments to schools for teaching programming. Most of these learning environments are web-based, interactive, and provide visual feedback. Our project follows these trends and builds on p5.js, a JavaScript library that provides software sketching features and rapid visual feedback to reduce the barrier for learning programming languages. We designed and implemented a new library for drawing geometric patterns using polar coordinate systems, p5.Polar. We then developed a game that incrementally teaches our library to players, and evaluated it with an online user study.

<p> The <i>Cool Robot</i> is a solar powered autonomous robot designed to support summertime science campaigns in the Polar Regions. While the overall design was proven in a previous deployment to Summit Greenland, it lacked the robustness for longer campaigns, and the ergonomics of accessing the interior of the robot were arduous and time consuming. The objectives of this thesis were to 1) redesign the solar panel system for improved performance in wind and rough terrain and for easier assembly and access to inside of the robot chassis, 2) update the power system controls and electronics for reliable and robust operation, 3) update all electrical systems using common, off-the-shelf components, 4) establish a common code base and communication protocol used by other similarly designed robots, 5) provide permanent data logging capability to evaluate mobility and the power system performance, and 6) develop and implement a sensor-based framework for detecting and avoiding dangerous levels of tilt which could result in roll-over. All of these objectives aim to increase the performance reliability of the <i>Cool Robot</i>. The data logging capability allows for collecting data to evaluate performance of the new power system. The reliability of the <i>Cool Robot</i> will be tested during a summer mission to Summit Greenland.</p>

In recent years, the scientific community has expressed interest in the ability to observe global climate indicators such as polar sea ice. Advances in microwave remote sensing technology have allowed a large-scale and detailed study of sea ice characteristics. This thesis provides the analysis and development of sea ice mapping algorithms for the SeaWinds scatterometer. First, an in-depth analysis of the Remund Long (RL) algorithm for SeaWinds is performed. From this study, several improvements are made to the RL algorithm which enhance its performance. In addition, a new method for automated polar sea ice mapping is developed for the SeaWinds instrument. This method is rooted in Bayes decision theory, and incorporates an adaptive model for seasonally fluctuating sea ice and ocean microwave signatures. The new approach is compared to the RL algorithm, to passive microwave data, and to high-resolution SAR imagery for validation.

Powerful error-correcting codes have enabled a dramatic increase in the bit density on the recording medium of hard-disk drives (HDDs). Error-correcting codes in magnetic recording require a low-complexity decoder and a code design that delivers a target error-rate performance. This dissertation proposes an error-correcting system based on polar codes incorporating a fast, low-complexity, soft-output decoder and a design that is optimized for error-rate performance in the magnetic recording channel. LDPC codes are the state-of-the-art in HDDs, providing the required error-rate performance on high densities at the cost of increased computational complexity of the decoder. Substantial research in LDPC codes has focused on reducing decoder complexity and has resulted in many variants such as quasi-cyclic and convolutional LDPC codes. Polar codes are a recent and important breakthrough in coding theory, as they achieve capacity on a wide spectrum of channels using a low-complexity successive cancellation decoder. Polar codes make a strong case for magnetic recording, because they have low complexity decoders and adequate finite-length error-rate performance. In their current form, polar codes are not feasible for magnetic recording for two reasons. Firstly, there is no low-complexity soft-output decoder available for polar codes that is required for turbo-based equalization of the magnetic recording channel. The only soft-output decoder available to date is a message passing based belief propagation decoder that has very high computational complexity and is not suitable for practical implementations. Secondly, current polar codes are optimized for the AWGN channel only, and may not perform well under turbo-based detector for ISI channels. This thesis delivers a powerful low-complexity error-correcting system based on polar codes for ISI channels. Specifically, we propose a low-complexity soft-output decoder for polar codes that achieves better error-rate performance than the belief propagation decoder for polar codes while drastically reducing the complexity. We further propose a technique for polar code design over ISI channels that outperform codes for the AWGN channel in terms of error rate under the proposed soft-output decoder.

This paper discusses the development of the Polar UDC. It examines some elements of the UDC specific to the Polar context, in particular the geographical auxiliary schedule. Some future plans for the implementation of UDC in a library and also in a museum context are outlined.

Las foliaciones no dicríticas de segundo tipo fueron caracterizadas por Mattei - Salem [Ma-Sa] en término de su multiplicidad y de su unión de separatrices. En este trabajo de tesis, damos otra caracterización a las foliaciones no dicríticas de segundo tipo con el polígono de Newton de la foliación y el de su unión de separatrices. De otro lado, Loray [Lo] enuncia una caracterización para un tipo de foliaciones con singularidades cuspidales que tienen la misma resolución que su unión de separatrices, sin embargo Fernández, Mozo y Neciosup [F-Mo-N] encuentran una impresición en la caracterización debido a que la condición es necesaria pero no suficiente. Lo que hacemos en este trabajo es caracterizar a dicha familia de foliaciones cuando son de segundo tipo y damos condiciones necesarias y suficientes cuando son de tipo curva generalizada en términos de su orden pesado. Finalmente, generalizamos el resultado de García Barroso y Gwozdziewicz [GB-G1] a foliaciones, esto es, descomponemos la curva polar de una foliación curva generalizada asociada a sus raíces aproximadas. Dicha descomposición viene expresada en función del tipo topológico de la separatriz de la foliación.<br>Tesis

In the next era of communications, where heterogeneous, asynchronous and ultra-low latency networks are drawn on the horizon, classical cryptography might be inadequate due to the excessive cost of maintaining a public-key infrastructure and the high computational capacity required in the devices. Moreover, it is becoming increasingly difficult to guarantee that the computational capacity of adversaries would not be able to break the cryptograms. Consequently, information-theoretic security might play an important role in the future development of these systems. The notion of secrecy in this case does not rely on any assumption of the computational power of eavesdroppers, and is based instead on guaranteeing statistical independence between the information message and the observed cryptogram. This is possible by constructing channel codes that exploit the noisy behavior of the channels involved in the communication. Although there has been very substantial research in the last two decades regarding information-theoretic security, little has gone to study and design practical codes for keyless secret communication. In recent years, polar codes have changed the lay of the land because they are the first constructive and provable channel codes that are able to provide reliability and information-theoretic secrecy simultaneously. Additionally, their explicit construction and the low complexity of the encoding/decoding schemes makes them suitable for the new generation of communication systems. The main objective of this dissertation is to provide polar coding schemes that achieve the best known inner-bounds on the capacity regions of different multiuser models over the discrete memoryless broadcast channel. These models not only impose a reliability constraint, but also some sort of information-theoretic secrecy condition in the presence of eavesdroppers. In general, we focus on describing the construction and the encoding/decoding schemes of the the proposed polar code for a particular setting. Then, we analyze the reliability and the secrecy performance of these schemes in order to prove that they are able to achieve these inner-bounds as the blocklength tends to infinity. The first part of the thesis drives the attention to two different models over the degraded broadcast channel that commonly appear in real communication systems. In this models, there are a set of legitimate receivers and a set of eavesdroppers that can be ordered based on the quality of their channels. According to this ordering, different reliability or secrecy constraints apply for each legitimate receiver or eavesdropper respectively. Moreover, we propose practical methods for constructing the polar codes for both models and analyze the performance of the coding schemes by means of simulations. Despite we only evaluate the construction for these two particular settings, the proposed methods are also suitable for any polar coding scheme that must satisfy some reliability and secrecy conditions simultaneously. In the second part of the dissertation we describe and analyze two different polar coding schemes for the general broadcast channel (where channels are not necessarily degraded) with two legitimate receivers and one eavesdropper. We consider a model where a confidential and a non-confidential message must be reliably decoded by both legitimate receivers in presence of an eavesdropper. Despite it is almost immediate to find an inner-bound on the capacity for this model using random coding arguments, how to secretly convey the same confidential message to both legitimate receivers using polar codes is not straightforward. We also analyze the setting where a transmitter wants to send different confidential and non-confidential messages to the corresponding legitimate receivers. We compare two inner-bounds on the capacity of this model, and we design a polar coding scheme that achieves the inner-bound that surely includes the other.<br>La criptografia clàssica o computacional pot suposar certs inconvenients en els sistemes de comunicació de nova generació que es basen en xarxes heterogènies, asíncrones i que requereixen baixa latència. Els motius principals són l'alt cost que suposa mantenir una infraestructura de clau pública i l'elevada capacitat computacional que requereix als dispositius electrònics. A més, cada cop és més difícil garantir que aquesta capacitat computacional dels dispositius adversaris no serà suficient per trencar els criptogrames. Per tant, la seguretat basada en la teoria de la informació pot tenir un rol molt important pel futur desenvolupament d'aquests sistemes. La noció de seguretat en aquest cas no es basa en cap suposició sobre la potència computacional dels adversaris, sinó que consisteix en garantir que el missatge que es vol transmetre i el criptograma enviat pel canal siguin independents estadísticament. Això és possible utilitzant una codificació que aprofita el comportament sorollós del canal involucrat en la comunicació. Malgrat durant les dues darreres dècades la recerca en el camp de la seguretat basada en la teoria de la informació ha estat important, s'han destinat pocs esforços al disseny de codis pràctics per tal de transmetre informació confidencial sense utilitzar claus secretes. Així i tot, en els últims anys, els codis polars, un tipus de codis bloc lineals, han demostrat ser molt útils per tal de transmetre informació sense errors i de forma confidencial des d'un punt de vista de la teoria de la informació. L'objectiu principal d'aquesta tesis és construir esquemes de codificació basats en codis polars que assoleixin la capacitat (o la millor aproximació coneguda) per diferents models sobre el canal de difusió (broadcast channel) amb presència d'adversaris. Aquests models no només imposen restriccions sobre la fiabilitat de la transmissió, sinó que també imposen restriccions sobre la confidencialitat des del punt de vista de la teoria de la informació. En general, per a cada model descriurem un esquema de codificació i després analitzarem el seu rendiment per demostrar que són capaços de transmetre informació de forma fiable i confidencial a la màxima taxa de transmissió possible quan la longitud del codi tendeix a infinit. La primera part d'aquesta tesis centra l'atenció en dos models de comunicació diferents pel canal degradat de difusió que representen molts de sistemes de comunicació reals. En aquests models, hi ha un conjunt de receptors legítims i un conjunt d'adversaris, i els canals de tots ells es poden ordenar en base a la seva qualitat. En base a aquest ordre, s'apliquen condicions de fiabilitat i de seguretat diferents per a cada receptor o adversari, respectivament. També, en aquesta part proposem mètodes pràctics de construcció dels codis polars i analitzem el seu rendiment mitjançant simulacions. Malgrat que només avaluem la construcció per aquests dos models particulars, els mètodes proposats es poden generalitzar per qualsevol esquema de codificació polar que hagi de satisfer condicions de fiabilitat i seguretat de forma simultània. En la segona part es descriuen i s'analitzen dos esquemes de codificació basats en codis polars pel canal de difusió general (on els canals individuals no necessàriament són degradats) compost per dos usuaris legítims i un adversari. Primer, considerem un model en què dos missatges s'han de transmetre de forma fiable als dos receptors de manera que un ha de ser confidencial davant la presència de l'adversari. En segon lloc, considerem un model on el transmissor vol enviar diferents missatges confidencials i no confidencials als dos receptors.

this is master tesis on characterisation and implementation of amplitude path for a polar modulation transmetter, targeted at bluethooth extended data rate ( EDR).bluethooth EDR uses quadrature modulation techniques to obtain higher data rates. these techniques use ampitude an phase modulation of a carrier to increas bitrate without increasing signal bandwidth compared to anly using amplitude or phas modulation. the amplitude path migjt be futher developed by investigating the use of higjer order anti-elaising filters together with group compesation. alternative solutions for the I/V-stage is also an important area of staudy.

: In this thesis, a serially-concatenated coding scheme with a polar code as the outer code and a low density generator matrix (LDGM) code as the inner code is firstly proposed. It is shown that that the proposed scheme provides a method to improve significantly the low convergence of polar codes and the high error floor of LDGM codes while keeping the advantages of both such as the low encoding and decoding complexity. The bit error rate results show that the proposed scheme by reasonable design have the potential to approach a performance close to the capacity limit and avoid error floor effectively. Secondly, a novel transmission protocol based on polar coding is proposed for the degraded half-duplex relay channel. In the proposed protocol, the relay only needs to forward a part of the decoded source message that the destination needs according to the exquisite nested structure of polar codes. It is proved that the scheme can achieve the capacity of the half-duplex relay channel while enjoying low encoding/decoding complexity. By modeling the practical system, we verify that the proposed scheme outperforms the conventional scheme designed by low-density parity-check codes by simulations. Finally, a generalized partial information relaying protocol is proposed for degraded multiple-relay networks with orthogonal receiver components (MRN-ORCs). In such a protocol, each relay node decodes the received source message with the help of partial information from previous nodes and re-encodes part of the decoded message for transmission to satisfy the decoding requirements for the following relay node or the destination node. For the design of polar codes, the nested structures are constructed based on this protocol and the information sets corresponding to the partial messages forwarded are also calculated. It is proved that the proposed scheme achieves the theoretical capacity of the degraded MRN-ORCs while still retains the low-complexity feature of polar codes.

Fabrication of nano-rod and micro-rod array templates and then overgrowth of semi-polar (11-22) and non-polar (11-20) GaN on the templates on sapphire have been performed. Two simple but cost-effective fabrication techniques based on self-organized nano-masks and ultraviolet (UV) photolithography approaches have been developed, respectively. Optimization in the fabrication of non-/semi-polar nano-rod structures and semi-polar micro-rod structures has been systematically performed. The GaN nano-rod and micro-rod arrays with high reproducibility and good uniformity across two inch wafers have been achieved. Metal organic chemical vapour deposition (MOCVD) has been employed to conduct GaN overgrowth on the semi-polar or non-polar GaN nano-rod array templates which are fabricated based on standard semi-polar or non-polar GaN on r-plane (for non-polar) or m-plane (for semi-polar) sapphire prepared using MOCVD. Great improvements in crystal quality for both semi-polar and non-polar GaN have been achieved, which have been confirmed by both x-ray and transmission electron microscopy (TEM) measurements. It has been found that the diameter of nano-rods plays a significant role in reducing dislocation density. With increasing diameter of nano-rods, the dislocation density of the overgrown GaN is reduced. By using the self-organized masks, a quick coalescence with a less than 1 µm thick layer has been achieved, which is much less than those using any conventional overgrowth techniques (typically 10-20 µm). An approach to the fabrication of semi-polar micro-rod GaN array structures has been developed, which is based on the combination of mask design and UV photolithography techniques. A systematic study on the overgrowth of semi-polar GaN on the semi-polar micro-rod GaN array structures have been performed as a function of the diameter of the micro-rods. A further reduction in the dislocation densities and especially basal stacking faults has been achieved compared with that using self-organized nano-mask approach. The mechanism for defect reduction in the GaN overgrown on nano-rod/micro-rod templates has been investigated by detailed TEM studies. The dislocations are either terminated by the SiO2 masks or the residue voids formed due to the large GaN lateral growth rate. The propagation of basal stacking fault can be blocked during the coalescence initiated from the sidewall of the adjacent nano-rods or micro-rods. InGaN/GaN multiple quantum wells (MQWs) have been grown on the semi-polar and non-polar overgrown GaN, respectively. The temperature dependent photoluminescence (PL) measurements demonstrate a significant enhancement in the internal quantum efficiency of InGaN/GaN MQWs grown on the overgrown GaN compared with that grown on as-grown c-plane, non-polar, and semi-polar GaN, respectively, as a result of the huge improvement in crystal quality and elimination or mitigation of the quantum confined Stark effect, which has been confirmed by excitation power dependent PL measurements. InGaN/GaN MQWs with a significant enhancement in indium incorporation have been achieved, demonstrating a major advantage of utilisation of semi-polar GaN for the growth of long wavelength emitters. So far, high optical performance with an emission wavelength of up to 590 nm has been demonstrated.

Sea f una curva plana irreducible con semigrupo (n, m), denotemos por K(n; m) el conjunto de curvas irreducibles topológicamente equivalentes a f, es sabido que el tipo topológico de la polar de una curva g, definida por P(g) = agx + bgy no es constante en el conjunto K(n; m) ver Ejemplo 1, o sea el tipo topológico de la polar no es un invariante topológico de la curva sino un invariente analítico. Sin embargo, Casas Alvero demostro que al menos generícamente el tipo topológico de la polar es constante en K(n; m) y su topología es determinada a partir de n y m. Nosotros daremos una prueba particular de esa a afirmación, describiendo además de modo explicito un abierto U en K(n; m) donde la topología de la polar es constante y bien determinada; además veremos el comportamiento de la polar de algunas curvas que no estan en el conjunto U.<br>Tesis

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 135-145).<br>features, with a deep, hot and rapid cyclone situated directly over each pole, and a rapid jet marking the cyclone boundary at 3° from the pole. Extant theories for the zonal jets preclude the possibility of a jet at such high latitudes. This thesis proposes and tests a moist convective hypothesis for polar cyclone formation. Using purely baroclinic forcing, with statistical characteristics motivated by moist convection observed on Jupiter and Saturn, a robust tendency to form a barotropic polar cyclone is identified. A 2 1/2 layer shallow water model is built to test our hypothesis. An 11-dimensional parameter space is explored to determine the most importance controls on cyclone formation. Two sets of experiments are performed: 1) Barotropic and baroclinic 'storms' are briefly forced and then allowed to freely evolve on the polar beta plane, and 2) Forced-dissipative simulations are run, with periodic and randomly placed storms, until statistical equilibrium is reached. Results confirm the well known tendency of positive vorticity anomalies to self-advect poleward if they are intense enough for nonlinear advection to be significant. Likewise, strong negative vorticity anomalies move equatorward. Simulations span several orders of magnitude of energy density, ranging from weak wave-dominated flows to strong cyclones that experience instabilities. We find that a range of behavior, including what is observed on all four giant planets as well as previous simulation studies, can be expressed by varying only 2 nondimensional control parameters: a second baroclinic deformation radius scaled by the planetary radius, LD2=a; and a total energy parameter Êp that scales with the kinetic+potential energy density of the system at statistical equilibrium. In the context of an idealized model, the difference between Jupiter's and Saturn's polar flow regimes may be explained by their different planetary and deformation radii.<br>by Morgan E. O'Neill.<br>Ph. D.

Nous nous intéressons dans cette thèse à l’optimisation conjointe de forme et d’anisotropie pour les structures surfaciques. Nous nous focalisons dans un premier temps sur l’analyse de ces structures minces modélisées par des coques. Le modèle utilisé pour décrire le comportement mécanique est celui de Naghdi communément utilisé pour les coques modérément épaisses et qui permet de prendre en compte l’effet transverse de déformation. La discrétisation par méthode éléments finis est réalisée avec des éléments Lagrange standards de classe C0. Nous considerons la simulation d’assemblage de coques en utilisant la méthode des éléments finis avec joint (mortier). Cette méthode est flexible, elle est adaptée à l’utilisation de maillages localement raffinés et/ou non-conformes, c'est-à-dire non coïncidents. La deuxième partie se consacre à la définition d’un paramétrage pour la conception optimale de champ d’anisotropie. Notre approche se base sur l’utilisation conjointe du formalisme polaire pour représenter le tenseur d’élasticité et le principe isogéométrique permettant de paramétrer les champs d’anisotropie par des fonctions de type B-splines. La dernière partie est dédiée à l’optimisation conjointe de forme et de propriétés matériaux. Le nombre de paramètres d’optimisation dans l’approche proposée est maîtrisée puisque les paramètres d’optimisation sontles coordonnées des points de contrôle. Nous considérons principalement pour l’optimisation un critère detype compliance<br>This thesis tackles the problem of the shape and anisotropy optimization of shell structures. The first part of this work focuses on the analysis of the shell model. The mechanical behavior of the structure is described using the Naghdi’s shell model which allows to take into account the transverse shear deformation. This model is typically used for shallow shells. We use a standard Lagrange C0 finite elements discretization and we numerically simulate the shell assemblings by means of the mortar technique. This approach enables the application of local refinements and the use of nonconforming mesh discretizations. The second part of this thesis aims at defining an effective parameterization for the optimal design of the shell’s distributed elastic properties. The method adopted is based on the joint use of a polar formalism to represent the elastic tensor and an isogeometric technique for the parameterization of the elastic tensor fields by CAD-based functions such as B-splines. The number of design variables thus only depends on the control points coordinates making the approach numerically manageable. The last part is devoted to the joint optimization of both the material properties and shape of the shell using the structure compliance as objective function

The objective of the proposed research is to extend the battery life in cellular handsets by improving the transmitter efficiency. Bandwidth efficient modulation formats, such as W-CDMA, encode much of the information in amplitude modulation. Therefore, linear transmitters must be used so as not to increase transmission errors, and cause interference in adjacent bands. Various engineering trade-offs were examined to find a suitable transmitter architecture for W-CDMA. Dynamic biasing of the transmitter power amplifier (PA) provides a simple way to improve efficiency for applications that require highly linear amplification. The envelope elimination and restoration (EER) PA or EER-based polar-modulated PA is an attractive solution since it has potential to achieve very high efficiency with high linearity. However, the major impediment to EER implementation has been the lack of power-efficient dynamic power supply circuits that can operate with sufficient modulation bandwidth, and simultaneously achieve the required modulation linearity. This work proposes several solutions to this problem. First, a dynamic supply circuit using delta modulation was designed and implemented. An open-loop EER PA with 48% peak efficiency was constructed and tested with a cellular band IS-95 CDMA signal with a bandwidth of 1.25 MHz. The low switching loss by using a delta modulator made the implementation of a wideband dynamic biasing circuit possible. Second, a dynamic supply circuit using dual-phase PWM was designed and implemented to achieve wider bandwidth, lower noise, and higher efficiency. An open-loop EER PA was implemented with the dynamic supply IC. A digital gain compensation scheme was developed to further increase bandwidth and linearity. This enables a dynamic supply circuit with lower switching frequency to have larger usable bandwidth with little increased power consumption. A cellular band W-CDMA voice signal was used to evaluate the performance of the overall PA. The PA achieved 50% efficiency while passing all required spectral specifications of W-CDMA standard. To increase the inherent low dynamic range of an EER PA, a dual-mode power amplifier combining an EER PA and power-level tracking PA was proposed. This work will contribute to the development of high efficiency, small-sized multi-mode linear PAs for battery-operated wireless handheld devices.

I Polar Codes sono la prima classe di codici a correzione d’errore di cui è stato dimostrato il raggiungimento della capacità per ogni canale simmetrico, discreto e senza memoria, grazie ad un nuovo metodo introdotto recentemente, chiamato ”Channel Polarization”. In questa tesi verranno descritti in dettaglio i principali algoritmi di codifica e decodifica. In particolare verranno confrontate le prestazioni dei simulatori sviluppati per il ”Successive Cancellation Decoder” e per il ”Successive Cancellation List Decoder” rispetto ai risultati riportati in letteratura. Al fine di migliorare la distanza minima e di conseguenza le prestazioni, utilizzeremo uno schema concatenato con il polar code come codice interno ed un CRC come codice esterno. Proporremo inoltre una nuova tecnica per analizzare la channel polarization nel caso di trasmissione su canale AWGN che risulta il modello statistico più appropriato per le comunicazioni satellitari e nelle applicazioni deep space. In aggiunta, investigheremo l’importanza di una accurata approssimazione delle funzioni di polarizzazione.

<p>Over the last few years the ship traffic in polar areas have been steadily increasing, especially north of Norway. This is largely due to the growing activity in that area and in northern Russia, mainly from oil and gas exploration and production. All indications suggest that this will continue into the foreseeable future. In this report a satellite based system for broadband communications to the area north of 65 northern latitude is discussed. Possible carrier frequency configurations and their propagation properties is analysed, and it is found that Ka-band, 20/30GHz, will give best performance. Various satellite orbits are then discussed, and a constellation that give continueous coverage and allow for easy handover is designed. It consists of four satellites in Molniya orbits with an eccentricity of approximately 0.72. Each satellite is then operational and quasi-stationary for six hours of every orbit, with two satellites above the coverage area at any time. Solutions for the satellite antennas are considered, and link budgets are presented. Active phased arrays are found to provide the best performance. A total uplink capacity of 1.6 Gbps is teoretically possible with a user terminal output power of 100W, but it is not deemed realizable. Instead a configuration with a total capacity on both uplink and downlink of about 1 Gbps is suggested. At the end of the report a range of issues, related to the realization of the satellite system, requiring future attention is summarized and briefly discussed.</p>

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>PROGRAMA DE EXCELENCIA ACADEMICA<br>Esta dissertação apresenta uma técnica de puncionamento orientada pela polarização para o projeto de códigos polares puncionados. A estratégia de puncionamento proposta consiste em reduzir a matriz geradora relacionando seu índice de linha com o princípio da polarização do canal. Os códigos puncionados construídos com base na polarização do canal são então considerados para a decodificação por cancelamento sucessivos (SC) com os bits perfurados conhecidos tanto no codificador como no decodificador. A Distância de Espectro (SD) e a Distância de Espectro Conjunta (JSD) são então utilizadas para análise de desempenho. Os resultados das simulações mostram que os códigos polares puncionados propostos superam os códigos polares puncionados existentes.<br>This thesis presents a polarization-driven puncturing technique for the design of punctured polar codes. The proposed puncturing strategy consists of reducing the generator matrix by relating its row index based on the channel polarization principle. The punctured codes constructed based on channel polarization are then considered with successive cancellation (SC) decoding and punctured bits known to both the encoder and the decoder. The Spectrum Distance (SD) and the Joint Spectrum Distance (JSD) are then used to performance analysis. Simulation results show that the proposed punctured polar codes outperform existing punctured polar codes.

This thesis reports on the use of buffer gas cooling to produce slow and intense molecular beams, with the aim of creating a source of molecules that can be used to measure the electron electric dipole moment. A beam of Yb is extracted from a buffer gas cell by entrainment in a flow of helium. The beam is characterised and simulations are performed of the helium flow through the cell to better understand the effect this has on the beam characteristics. The velocity of the beam is found to vary between 65 m/s[superscript -1] and 204 m/s[superscript -1] depending on the helium flow through the cell, in agreement with the predictions of the simulations. The temperature of the beam is 2.4 K and the minimum divergence is 12°. The percentage of Yb that is extracted from the cell is ~10%. Sources which use a pulsed valve to produce a supersonic jet are also characterised at cryogenic temperatures. The addition of a thermalisation cell is found to produce beams that are slower, colder and more intense. The peak beam intensity is 4.5×10[superscript 10] molecules per seradian per pulse, the velocity (206 ± 5) m/s and the translational temperature is (12.3 ± 0.5) K. An electric decelerator is used to decelerate a pulse of YbF molecules from 300 m/s[superscript -1] to 276 m/s[superscript -1] by confining them to a travelling trap. Simulations of the molecules in the decelerator show that its acceptance is greater than those demonstrated previously. A detailed understanding of this deceleration is developed. The Franck-Condon factors for the A[superscript 2]Π[subscript 1/2] (v = 0) − X[superscript 2]Σ[superscript +] (v - 0, 1, 2) transition of YbF are measured. The results show that, using three lasers, the molecule could be laser-cooled.

Source coding, originally envisaged by Claude Shannon in 1948 in his landmarkpaper "A Mathematical Theory of Communication" remained impractical forthe most part of the 20th century. However several advances were made incoding theory of which the latest-Polar Codes introduced by Erdal Arikan in2008 is highly promising. Polar Codes have modest encoding and decoding complexities,while providing a construction that directly leads to the fundamentalbounds obtained by Shannon. We are progressing further into the InformationAge, where high resolution videos are streamed over the Internet and variousdevices gather massive amounts of data while connected to each other in communicationnetworks. Hence the practical implication of an ecient and securesource coding scheme is signicant. In this thesis, we implement a source codingproblem called the Common helper in a Wyner-Ziv Network using polarcodes. Additionally the above construction leads to the lossy compression of aBernoulli Source and might provide an insight on how to develop ecient lossysource compression over a more general network.Source coding, originally envisaged by Claude Shannon in 1948 in his landmarkpaper "A Mathematical Theory of Communication" remained impractical forthe most part of the 20th century. However several advances were made incoding theory of which the latest-Polar Codes introduced by Erdal Arikan in2008 is highly promising. Polar Codes have modest encoding and decoding complexities,while providing a construction that directly leads to the fundamentalbounds obtained by Shannon. We are progressing further into the InformationAge, where high resolution videos are streamed over the Internet and variousdevices gather massive amounts of data while connected to each other in communicationnetworks. Hence the practical implication of an ecient and securesource coding scheme is signicant. In this thesis, we implement a source codingproblem called the Common helper in a Wyner-Ziv Network using polarcodes. Additionally the above construction leads to the lossy compression of aBernoulli Source and might provide an insight on how to develop ecient lossysource compression over a more general network.<br>Källkodning, som ursprungligen planerades av Claude Shannon är 1948 i sittlandmärkes paper "A Mathematical Theory of Communication" var opraktiskför det mesta av 1900 talet. Men era framsteg gjordes i kodningsteoridär de senaste Polarkoderna infördes av Erdal Arikan 2008 är mycket lovande.Polära koder har blygsamma kodnings- och avkodningskomplexiteter,samtidigt som de ger en konstruktion som direkt leder till de grundläggandegränserna som erhållits av Shannon. Vi går vidare in i informationsåldern,där videoklipp med hög upplösning streamas över Internet och olika enhetersamlar massiva datamängder medan de är anslutna till varandrar i kommunikationsnät. Därför är den praktiska implikationen av ett effektivt och säkertkällkodningssystem väsentligt. I den här avhandlingen implementerar vi ettkällkodproblem som kallas den gemensamma hjälpen i ett Wyner-Ziv-nätverkmed polarkoder. Dessutom leder ovanstående konstruktion till en förlustfullkomprimering av en Bernoulli-källa och kan ge en inblick i hur man utvecklareffektiv förlustkällkomprimering över ett mer generellt nätverk.

We construct polar codes for binary relay channels with orthogonal receiver components. We show that polar codes achieve the cut-set bound when the channels are symmetric and the relay-destination link supports compress-and-forward relaying based on Slepian-Wolf coding. More generally, we show that a particular version of the compress-and-forward rate is achievable using polar codes for Wyner-Ziv coding. In both cases the block error probability can be bounded as O(2-Nβ) for 0 &lt; β &lt; 1/2 and sufficiently large block length N.<br><p>© 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111207</p>

Autonomous instrumentation is used to collect scientific data in very remote locations, especially in the polar regions. Retrieving data from these instruments is often done by the use of satellite communications or by manual retrieval, the latter often requiring the use of an aircraft. This research focussed on the use of HF radio (i.e frequencies of 3-30MHz) as a cheaper technology for data communications in the polar regions and concentrated on three main areas of work: • the development of a channel simulator for high-latitude HF channels based on work by Warrington, Siddle and Stocker (2006) and using it for performance tests of existing HF modems • work on HF modem waveforms, including Polynomial Cancellation Coding OFDM (PCC-OFDM) and conventional OFDM, to try and create waveforms suitable for the more demanding high-latitude channels • an oblique propagation study using an OFDM waveform between Halley and Rothera stations in Antarctica, a 1600km sub-auroral link run for twelve months close to solar minimum. This work has shown that existing military HF modems (MIL-STD-188-110B) perform reasonably well in all but the most demanding high-latitude HF channels simulated. The oblique propagation study showed that a total annual data volume of around 400MB could be transmitted over the Halley-Rothera link, showing that HF can carry sufficient data to be useful for data retrieval. Data volumes were at their highest in the austral summer, but limited communications were possible year-round.

Polar codes are a new class of forward error-correcting codes recently discovered by Arıkan. They are the first codes with an explicit construction to provably achieve capacity, a theoretical limit governing the transmission of information in the presence of noise, for a wide variety of communication channels. Since polar codes have a very regular construction, they also lend themselves very well to hardware implementations. This thesis presents the design work underlying the development of two generations of hardware decoders for polar codes based upon the successive-cancellation algorithm. Making use of SRAM-based semi-parallel architectures, those designs allow very large polar codes to be implemented on Altera Stratix IV and Stratix V FPGA targets: up to N=2^17 for the first generation, and N=2^21 for the second-generation design. The second-generation decoder also features variable quantization levels to reduce its memory footprint, look-ahead to improve throughput, a redesigned partial-sum encoder based on a novel semi-parallel design for increased scalability, and an overlapped frame loading mechanism allowing full-speed operation of the decoder with a single input buffer.<br>Les codes polaires constituent une nouvelle classe de codes correcteurs d'erreurs sans voie de retour (forward error correction) découverte récemment par Arıkan. Ce sont les premiers codes ayant une construction explicite à atteindre la capacité du canal, une limite théorique s'appliquant à l'envoi d'information sur un canal en présence de bruit, et ce pour de nombreux types de canaux. La construction très régulière des codes polaires simplifie la conception de décodeurs matériels. Ce mémoire présente deux générations de décodeurs matériels pour les codes polaires basés sur l'algorithme d'annulation successive. À l'aide d'une architecture partiellement parallèle s'appuyant sur des mémoires SRAM, ces décodeurs permettent la synthèse de codes polaires très longs. Sur des FPGAs Altera Stratix IV et Stratix V, nous avons pu synthétiser des décodeurs de taille N=2^17 pour la première génération et N=2^21 pour la seconde. Afin d'atteindre cette taille de codes, la seconde génération de décodeurs s'appuie entre autres sur une quantification variable afin de réduire son empreinte mémoire, sur un circuit de génération de sommes partielles novateur, sur une technique de décodage anticipé pour améliorer son débit et sur un chargement chevauché des trames pour atteindre son débit maximal sans registres d'entrée additionnels.

Master of Science<br>Department of Statistics<br>Gary L. Gadbury<br>This report presents an analysis of data resulting from a lipidomics experiment. The experiment sought to determine the changes in the lipidome of big bluestem prairie grass when exposed to stressors. The two stressors were drought (versus a watered condition) and a rust infection (versus no infection), and were whole plot treatments arranged in a 2 by 2 factorial. A split plot treatment factor was the position on a sampled leaf (top half versus bottom half). In addition, samples were analyzed at different times, representing a blocking factor. A total of 110 samples were used and, for each sample, concentrations of 137 lipids were obtained. Many lipids were not detected for certain samples and, in some cases, a lipid was not detected in most samples. Thus, each lipid was analyzed separately using a modeling strategy that involved a combination of mixed effects linear models and a categorical analysis technique, with the latter used for certain lipids to determine if a pattern of observed zeros was associated with the treatment condition(s). In addition, p-values from tests of fixed effects in a mixed effect model were computed three different ways and compared. Results in general show that the drought condition has the greatest effect on the concentrations of certain lipids, followed by the effect of position on the leaf. Of least effect on lipid concentrations was the rust condition.

Linear power amplifiers used to implement the Ultra-Wideband standard must be backed off from optimum power efficiency to meet the standard specifications and the power efficiency suffers. The problem of low efficiency can be mitigated by polar modulation. Digital polar architectures have been employed on numerous wireless standards like GSM, EDGE, and WLAN, where the fractional bandwidths achieved are only about 1%, and the power levels achieved are often in the vicinity of 20 dBm. Can the architecture be employed on wireless standards with low-power and high fractional bandwidth requirements and yet achieve good power efficiency? To answer these question, this thesis studies the application of a digital polar transmitter architecture with parallel amplifier stages for UWB. The concept of the digital transmitter is motivated and inspired by three factors. First, unrelenting advances in the CMOS technology in deep-submicron process and the prevalence of low-cost Digital Signal processing have resulted in the realization of higher level of integration using digitally intensive approaches. Furthermore, the architecture is an evolution of polar modulation, which is known for high power efficiency in other wireless applications. Finally, the architecture is operated as a digital-to-analog converter which circumvents the use of converters in conventional transmitters. Modeling and simulation of the system architecture is performed on the Agilent Advanced Design System Ptolemy simulation platform. First, by studying the envelope signal, we found that envelope clipping results in a reduction in the peak-to-average power ratio which in turn improves the error vector magnitude performance (figure of merit for the study). In addition, we have demonstrated that a resolution of three bits suffices for the digital polar transmitter when envelope clipping is performed. Next, this thesis covers a theoretical derivation for the estimate of the error vector magnitude based on the resolution, quantization and phase noise errors. An analysis on the process variations - which result in gain and delay mismatches - for a digital transmitter architecture with four bits ensues. The above studies allow RF designers to estimate the number of bits required and the amount of distortion that can be tolerated in the system. Next, a study on the circuit implementation was conducted. A DPA that comprises 7 parallel RF amplifiers driven by a constant RF phase-modulated signal and 7 cascode transistors (individually connected in series with the bottom amplifiers) digitally controlled by a 3-bit digitized envelope signal to reconstruct the UWB signal at the output. Through the use of NFET models from the IBM 130-nm technology, our simulation reveals that our DPA is able to achieve an EVM of - 22 dB. The DPA simulations have been performed at 3.432 GHz centre frequency with a channel bandwidth of 528 MHz, which translates to a fractional bandwidth of 15.4%. Drain efficiencies of 13.2/19.5/21.0% have been obtained while delivering -1.9/2.5/5.5 dBm of output power and consuming 5/9/17 mW of power. In addition, we performed a yield analysis on the digital polar amplifier, based on unit-weighted and binary-weighted architecture, when gain variations are introduced in all the individual stages. The dynamic element matching method is also introduced for the unit-weighted digital polar transmitter. Monte Carlo simulations reveal that when the gain of the amplifiers are allowed to vary at a mean of 1 with a standard deviation of 0.2, the binary-weighted architecture obtained a yield of 79%, while the yields of the unit-weighted architectures are in the neighbourhood of 95%. Moreover, the dynamic element matching technique demonstrates an improvement in the yield by approximately 3%. Finally, a hardware implementation for this architecture based on software-defined arbitrary waveform generators is studied. In this section, we demonstrate that the error vector magnitude results obtained with a four-stage binary-weighted digital polar transmitter under ideal combining conditions fulfill the European Computer Manufacturers Association requirements. The proposed experimental setup, believed to be the first ever attempted, confirm the feasibility of a digital polar transmitter architecture for Ultra-Wideband. In addition, we propose a number of power combining techniques suitable for the hardware implementation. Spatial power combining, in particular, shows a high potential for the digital polar transmitter architecture. The above studies demonstrate the feasibility of the digital polar architecture with good power efficiency for a wideband wireless standard with low-power and high fractional bandwidth requirements.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>PROGRAMA DE EXCELENCIA ACADEMICA<br>O problema da predição das estruturas de proteínas (Protein Structure Prediction (PSP)) é um dos desafios mais importantes na biologia molecular. Pelo fato deste problema ser muito difícil, têm sido propostos diferentes modelos simplificados para resolvê-lo. Um dos mais estudados é o modelo, Hidrofóbico-Polar (HP), o modelo HP fornece uma estimativa da energia da proteína com base na soma de interações entre pares de aminoácidos hidrofóbicos (contatos H-H). Entretanto, apesar das simplificações feitas no modelo HP, o problema permanece complexo, pertencendo à classe NP-Difícil. Muitas técnicas têm sido propostas para resolver este problema entre elas, técnicas baseadas em algoritmos genéticos. Em muitos casos, as técnicas baseadas em AG foram usadas com sucesso, mas, no entanto, abordagens utilizando AG muitas vezes não tratam adequadamente as soluções geradas, prejudicando o desempenho da busca. Além disso, mesmo que eles, em alguns casos, consigam atingir o mínimo de energia conhecido para uma conformação, estes modelos não levam em conta a forma da proteína um fator muito importante na hora de obter proteínas mais compactas. Foi desenvolvido um algoritmo genético multiobjetivo para PSP no modelo HP, de modo de avaliar de forma mais eficiente, as conformações produzidas. O modelo utiliza como avaliação uma combinação baseada no número de colisões, número de contatos hidrofóbicos, compactação dos aminoácidos hidrofóbicos e hidrofílicos, obtendo, desta forma estruturas mais naturais e de mínima energia. Os resultados obtidos demonstram a eficiência desse algoritmo na obtenção de estruturas proteicas compactas providenciando indicadores da compactação dos aminoácidos hidrofóbicos e hidrofílicos da proteína.<br>The problem of protein structured prediction (PSP) is one of the most important challenges in molecular biology. Because this problem is very difficult, different simplified models have been proposed to solve it. One of the most studied is the Hydrophobic-Polar model HP this model provides an estimate of the protein energy based on the sum of hydrophobic contacts. However, despite the simplifications made in the HP model, the problem remains complex, belonging to the class of NP-Hard problems. Many techniques have been proposed to solve this problem as genetic algorithms. In many cases the GA techniques have been used successfully, but, however, with GA approaches often do not adequately address the generated solutions, impairing the performance of the search. Furthermore, in some cases would attain the minimum energy for a known conformation, these models do not take care the protein shape, a very important factor to obtain more compact proteins. This work developed a multiobjective genetic algorithm to PSP in HP model evaluating more efficiently, the conformations produced. This model is a combination of assessment based on the collisions numbers, hydrophobic contacts, hydrophobic and hydrophilic core compression, obtaining thus more natural structures with minimum energy. The results demonstrate the efficiency of this algorithm to obtain protein structures indicators providing compact compression of the hydrophobic and hydrophilic core protein.

This doctoral study mainly considers the Wind Energy resource and focuses on the electromagnetic aspects of generators for direct drive solutions in this field. Despite the strong employing by many constructor of geared technology in Wind Turbines Generators, a transmission/gear box reduces both, eciency and reliability: the losses due to the transmission potentially compromise the sustainability of the electromechanical system. A better solution is the multipolar low speed direct drive train. Permanent magnet machines offer compactness and the absence of brushes with respect to traditional machines. Material in the armature can be saved using fractional slot windings. This type of machine exhibits many advantages such as short end windings, high slot fill factor, high efficiency and power density together with electrical redundancy, which allows the modularization of the active part and fault-tolerance capabilities. However, space harmonics of the magneto-motive force (MMF) in fractional slot windings lead to considerable rotor losses. The computation of these losses according to standard procedures (e.g. Steinmetz equation or models for massive body within homogeneous field) is not satisfactory. The MMF harmonics move asynchronously with respect to the rotor, inducing currents in any conductive rotor parts, e.g. the metallic iron yoke which supports the magnetic poles and the rare earth permanent magnets (PMs), acting on their working temperature which is strictly related to the performance of PMs. The reduction of the residual ux density causes a decrease both in the back electromotive force (EMF) and in the electromagnetic torque. The reduction of the magnetic eld increases the risk of an irreversible demagnetization of the PMs. The MMF space harmonic amplitude and frequency depend on the particular combination of number of slots and poles. The amount of such losses increases dramatically with the size of the machine becoming a crucial aspect in the design of a large diameter (v 2 - 3m) multipolar direct drive generators with PMs. A proper selection of the winding of the machine,fixing the number of slot and poles represents an improvement in the sustainability of the electromechanical conversion process: losses are limited and a higher eciency is achieved. If efficiency is better even less active material is wasted. This part of the doctoral study has been accomplished at the Electric Drives Laboratory at the Department of Industrial Engineering of the University of Padova during a partnership with Leitwind A.G.(in Sterzing, Italy), which operates in the Wind Energy Market. The aim is to design a large diameter generator (v 4m), which will be employed in the prototype of a 3 MW wind turbine. The will of Leitwind to implement a method to predict rotor losses in large machines with permanent magnet and fractional slot windings is the key basic point to be solved. The existing LW15C generator for LTW77 (1.5 MW rated power) wind turbine is analyzed by means of analytical relations and finite elements: it represents the starting point of this study. A method to calculate rotor losses due to the high harmonic contents of the fractional slot winding is applied. Such estimated losses are then compared with the results of experimental test benches with "full-scale" prototypes. The same study is then repeated on SFA motor (500 kW rated), employed in ropeways transport in Leitner A.G. plants. Both Leitner and Leitwind belong to the Leitner Technologies Group. Test bench results are finally compared with the values from the analysis. Starting from both the experience on LW15C generator and SFA motor the design of LW30A prototype generator for Leitwind 3MW wind turbine is chosen. Dierent topologies of PM machines with fractional slot winding are then investigated and compared with the switching ux configuration (SFPM), both with rare earths and ferrite PMs. The possibility to integrate a huge magnet quantity in the armature of the SFPM machine and the ux concentration principle can lead to a cost eective solution which must be carefully evaluated without considering the performance of the machine only. The structure of the rotor is robust and simple, like in classical reluctance machines. The robustness against PMs demagnetization is a crucial point to investigate. To extend the scenario of renewable energy, the wave energy resource is brie y overviewed and some topologies for linear direct drive generator in this field are investigated. In order to increase the thrust density the possibility of employing a double-sided structure is analyzed. The employing of ferrite PMs is also considered: despite their low energy with respect to rare earth magnets they have a lower impact on environment and human health. The extraction process of ferrite is similar to the iron one, while rare earths must be separated from radio elements. Main contributions of the thesis To the knowledge of the author, the contributions of this thesis for the upcoming researchers in electrical machines for renewable energy eld are: • The application of straight lined model and of the current sheet method to calculate rotor losses in large direct drive permanent magnet machines. The results of the test bench activity on real machines are then described and compared with the prediction. • Selection of number of slots and poles for fractional winding direct drive large generators. • Comparison of the switching ux machine with other well known machine topologies, including demagnetization behavior and ferrite PMs, more sustainable than rare earth ones. • Investigation on dierent linear modules topologies for wave energy, including double side switching ux topology. Outline of the thesis Chapter 1 provides an overview on renewable energy conversion field and presents the company Leitwind A.G. Chapter 2 describes the analysis and modeling of the LW15C generator for 1.5 MW wind turbine. Then a similar study has been performed for the SFA motor for ropeways applications. Both analytical and finite elements model have been developed/implemented and are compared to the results of experimental test bench activities. The same models are applied to the analysis of the new LW30A generator. Chapter 3 faces the topic of rotor losses in order to model them with the straight lined model and the current sheet method. The rotor losses computation is considered and described. Predicted values are compared with the test bench ones. Chapter 4 establishes a scaling law for rotor losses in fractional slot PM machines. Chapter 5 provides the selection of the number of slots and poles to design the new LW30A generator for 3.0 MW wind turbine. The validity of the Index of Rotor Losses obtained from the straight lined model is investigated and applied. Chapter 6 describes the comparison of fractional winding machine with a small switching ux permanent magnet machine, both with rare earth and ferrite PMs. The demagnetization behavior of the different machine topologies is analyzed. Chapter 7 considers linear drives for Wave energy conversion with different topologies, including the double side switching flux machine<br>Questo lavoro di dottorato considera principalmente la Risorsa Eolica e si focalizza sulle caratteristiche elettromagnetiche dei generatori a presa diretta per questa applicazione. Malgrado molti Costruttori di turbine eoliche usino congurazioni comprendenti il moltiplicatore di giri, la presenza di quest'organo di trasmissione causa una perdita di ecienza del sistema elettromeccanico che va a comprometterne la sostenibilità. Una soluzione multipolare a bassa velocita di rotazione e presa diretta tra generatore e pale della turbina e quindi adottata. Si sceglie l'utilizzo del magnete permanente grazie alla sua compattezza e all'assenza di spazzole in paragone alle soluzioni di macchina sincrona tradizionale. L'avvolgimento frazionario e adottato per risparmiare materiale nell'avvolgimento di armatura della macchina. Questo tipo di congurazione presenta evidenti vantaggi come la lunghezza ridotta delle testate, il buon fattore di riempimento delle cave, elevati rendimento e fattore di potenza. Essa si presta inoltre a soluzioni circuitalmente ridondanti che consentono una struttura modulare della parte attiva, con la capacita di tollerare i guasti. D'altro canto, le armoniche spaziali della forza magneto motrice (MMF) dovuta all'avvolgimento frazionario causano perdite nel rotore di entita notevole. I metodi tradizionali di calcolo delle perdite (formula di Steinmetz o modelli di corpi solidi in campo magnetico uniforme) non forniscono risultati soddisfacenti per queste perdite. La forza magneto motrice risulta non sincrona con il rotore della macchina, con conseguente indursi di correnti parassite in ogni parte conduttrice del rotore, come nel giogo metallico che sorregge i poli magnetici e nei magneti stessi (terre rare). Le perdite nei magneti ne causano il riscaldamento, con conseguente calo delle prestazioni della macchina. La riduzione del campo dei magneti dovuta all'aumento di temperatura aumenta il rischio di smagnetizzazione irreversibile. L'ampiezza delle armoniche spaziali di forza magneto motrice e la loro frequenza vista dal rotore dipendono dalla particolare combinazione cave{poli dell'avvolgimento scelto. L'entita di queste perdite cresce notevolmente con l'aumentare delle dimensioni della macchina, divenendo un aspetto cruciale nella progettazione di macchine multipolari a presa diretta di grande diametro (. 2m) con magnete permanente. Una scelta adeguata del rapporto cave{poli dell'avvolgimento, signica un notevole miglioramento della sostenibilita del processo di conversione elettromeccanica: le perdite vengono ridotte e il rendimento migliora. Se il rendimento migliora, signica che meno materiale e stato sprecato. Questa parte del lavoro di tesi si e svolta presso il Laboratorio di Azionamenti Elettrici nel Dipartimento di Ingegneria Industriale dell'Universita di Padova nell'ambito di un contratto di ricerca voluto da Leitwind SpA (VIpiteno, Italia). Leitwind e un costruttore di turbine eoliche. Lo scopo e progettare un generatore di grande diametro (v 4m) per il prototipo di turbina eolica da 3 MW. Compresa l'importanza del fenomeno delle perdite rotoriche, la volonta di Leitwind e svilupparne calcolo per scegliere l'avvolgimento della nuova macchina. Il generatore Leitwind esitente, denominato LW15C, per la turbina LTW77 (potenza nominale 1.5 MW) e analizzato sia con modelli analitici che con gli elementi niti. Questo generatore e la base di partenza di questo studio. Viene applicato un metodo per il calcolo delle perdite rotoriche indotte dall'elevato contenuto armonico dell'avvolgimento frazionario. Le perdite cos ottenute sono confrontate con i risultati dell'attivita del banco prova su macchine reali. Con lo stesso approccio si studia e si modella il motore diretto per trazione funiviaria SFA (500 kW di potenza nominale) negli impianti Leitner. Leitner e Leitwind appartengono al Gruppo Leitner Technologies. I risultati del banco prova sono confrontati con i valori calcolati. La progettazione del nuovo generatore LW30A e sviluppata a partire dai modelli creati per il generatore LW15C e il motore diretto SFA. Vengono poi studiate dierenti topologie di macchina a magnete permanente con avvolgimento frazionario per confrontarle con la congurazione switching ux (SFPM). Lo studio prende in considerazione sia magneti di terre rare, che di ferrite. La possibilità di integrare una notevole quantita di magnete nella parte di armatura della macchina SFPM e il principio di concentrazione di usso portano ad una soluzione con un buon rapporto costi prestazioni, che pero deve essere valutata non solo da un punto di vista di prestazioni. La struttura del rotore di questa macchina e semplice e robusta, come per le macchine a riluttanza. Il comportamento della topologia SFPM a smagnetizzazione dei magneti permanenti risulta un punto cruciale da indagare. Per allargare lo studio ad un'altra Fonte Rinnovabile, l'energia da moto ondoso e brevemente descritta e vengono confrontate alcune topologie di generatori lineari per questa applicazione. Uno struttura a doppio statore viene studiata con l'intento di massimizzare la spinta sulla parte mobile. Si considera inoltre l'utilizzo dei magneti in ferrite: malgrado il loro basso prodotto di energia rispetto ai magneti in terre rare, essi risultano meni nocivi per l'ambiente e la salute dell'uomo: il processo di estrazione delle terre rare coinvolge infatti elementi radioattivi, mentre l'estrazione della ferrite e in tutto simile a quella del ferro. Contributi principali della tesi I principali contributi di questo lavoro di tesi alla ricerca futura nell'ambito delle energie rinnovabili si possono cos sintetizzare: • L'applicazione del modello a strati e del metodo dei punti corrente nel calcolo delle perdite rotoriche di macchine elettriche a presa diretta di grande diametro, con magneti permanenti. I risultati dell'attivita sperimentale su banco prova di grosse macchine reali sono confrontati con i valori calcolati. • La scelta del numero di poli e di cave nella progettazione di macchine a presa diretta di grande diametro, con avvolgimento frazionario. • Confronto della macchina switching ux con topologie di macchina note, comprendendo la smagnetizzazione del magnete e l'utilizzo della ferrite, materiale più sostenibile delle terre rare. • Studio di diverse topologie di generatore lineare per generazione da moto ondoso, includendo la topologia switching ux a doppio statore. Struttura della tesi Capitolo 1 : presenta una breve panoramica sull'energia rinnovabile eolica e da moto ondoso e descrive l'azienda Leitwind SpA. Capitolo 2 : descrive la modellazione e l'analisi delle macchine studiate, sia con metodi analitici che con gli elementi niti: sono inclusi i risultati dell'attivita sul banco prova. I modelli, sviluppati sul generatore LW15 e sul motore SFA sono poi applicati al nuovo generatore LW30A. Capitolo 3 : aronta la tematica del calcolo delle perdite rotoriche, sviluppando il modello a strati e il metodo dei punti corrente. Viene descritto il calcolo delle perdite rotoriche. Si aronta la validazione dei metodi di calcolo al banco prova. Capitolo 4 : ricava una legge di scala per le perdite rotoriche per macchine a magnete permanente ad avvolgimento frazionario. Capitolo 5 : presenta la scelta del rapporto cave{poli nel progetto del nuovo generatore LW30A per la turbina da 3.0 MW LTW 101. Viene investigata la possibilità di applicare l'Indice delle Perdite Rotoriche, ricavato dal modello a strati. Capitolo 6 : confronta diverse topologie di macchine ad avvolgimento frazionario con la congurazione switching ux, sia con terre rare che con ferrite. Si aronta il fenomeno della smagnetizzazione sulle diverse topologie di macchina. Capitolo 7 : prende in considerazione topologie di macchina lineare per conversione da moto ondoso. Include la congurazione switchng ux a doppio statore

Thesis (Ph.D.)--Boston University<br>The family of nitride semiconductors has had a profound influence on the development of optoelectronics for a large variety of applications. However, as of yet there are no native substrates commercially available that are grown by liquid phase methods as with Si and GaAs. As a result, the majority of electronic and optoelectronic devices are grown heteroepitaxially on sapphire and SiC. This PhD research addresses both the development of polar and nonpolar GaN and AIN templates by Hydride Vapor Phase Epitaxy (HVPE) on sapphire and SiC substrates, as well as the growth and characterization of optoelectronic devices on these templates by molecular beam epitaxy (MBE). Polar and non-polar GaN templates have been grown in a vertical HVPE reactor on the C- and R-planes of sapphire respectively. The growth conditions have been optimized to allow the formation for thick (50µm) GaN templates without cracks. These templates were characterized structurally by studying their surface morphologies by SEM and AFM, and their structure through XRD and TEM. The polar C-plane GaN templates were found to be atomically smooth. However, the surface morphology of the non-polar GaN films grown on the R-plane of sapphire were found to have a facetted surface morphology, with the facets intersecting at 120° angles. This surface morphology reflects an equilibrium growth, since the A-plane of GaN grows faster than the M-planes of GaN due to the lower atomic density of the plane. For the development of deep-UV optoelectronics, it is required to grow AIGaN quantum wells on AIN templates. However, since AIN is a high melting point material, such templates have to be grown at higher temperatures, close to half the melting point of the material (1500 °C). As these temperatures cannot be easily obtained by traditional furnace heating, an HVPE reactor has been designed to heat the substrate inductively to these temperatures. This apparatus has been used to grow high-quality, transparent AIN films with a screw dislocation density of 10^6 cm^-2 on sapphire repeatedly. On such templates, both lnGaN- and AIGaN-based quantum wells (QWs) and quantum dots (QDs) were formed by MBE and were characterized. lnGaN/GaN and AIGaN/AIN QWs were grown on the non-polar GaN templates and found to emit at near green and deep UV respectively with internal quantum efficiency (IQE) close to 90%. The lnGaN GaN QWs and QDs have been investigated to understand the influence of plasmonic nanoparticles on the efficiency of corresponding green LEOS.

Using density functional theory (DFT) we demonstrate that the adsorption of large cations such as potassium or cesium facilitates the epitaxial growth of polar LaAlO₃ (LAO) on SrTiO₃ (STO). The low ionization potential of K favors efficient electron transfer to the STO conduction band and results in a 2D electron gas which exactly compensates for the diverging potential with increasing layer thickness. For large cations like K or Cs, DFT total energy considerations show that they remain adsorbed on the LAO surface and do not enter substitutionally into LAO. These results suggest a novel scheme for growing clean LAO/STO interface systems, and polar systems in general, by performing the growth process in the presence of large, low ionization potential alkali metal ions.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate

Trimethylamine-n-oxide (TMAO) is a metabolite found in plasma/serum in humans. Elevated levels of TMAO have been associated with several types of heart disease. It’s therefore of interest to make a simple analytical method to analyse TMAO and other metabolites that are degraded to TMAO, including betaine. In this study, the goal was to develop a method for the sample preparation and analysis of these compounds in human plasma. Sample preparation was performed with an Ostro 96-well method for sample clean-up. The analysis was performed by ultraperformance liquid chromatography – hydrophilic interaction liquid chromatography – tandem masspectrometry (UPLC-HILIC-MS/MS) in multiple reaction monitoring (MRM)-mode using electrospray ionization in positive mode (ESI+)-mode as the ion source. The analytes eluted under five minutes and were all baseline separated in the chromatogram. TMAO and betaine were quantified in quality control (QC) plasma samples using external calibration. Concentration of TMAO ranged from 132 ng/mL – 253 ng/mL and 1025-2084 ng/mL for betaine. Due to the lack of isotopically labelled standards for TMAO and betaine, valine-d8 was tested as an internal standard for the extraction; however, it was not a suitable option due to the low recovery obtained (5-34%) and the low response in ESI+. The recovery needs to be investigated further using isotopically labelled TMAO or betaine. Overall, the developed UPLC-HILIC-MS/MS method was found to be suitable for analysis of TMAO and betaine in human plasma. Further development and validation is required before application to samples from clinical studies.

Airlines use the polar routes because for some flights the shortest route (the great circle) takes them over the polar regions. However, a lack of VHF ground stations over the oceans and within polar regions means that aircraft have to rely on long-range HF communications via the ionosphere. The ionosphere is affected by space weather more intensively in the high latitude regions. In severe space weather conditions, ionospheric HF communications become impossible, and aircraft have to be re-routed to lower latitudes. This increases the flight time, cost, passenger and flight loadings and impact on the environment. The research reported in this thesis designs a model of HF propagation that can provide nowcasting (and forecasting) to advice airlines of the likely quality of HF communications. The model consists of electron density profile, ray-tracing, and signal loss and antenna gain considerations. An electron density model partially comprises a background ionosphere, and the work presented in this thesis contributes by proposing an assimilative model based on the International Reference Ionosphere (IRI). This is then perturbed by ionospheric structures that occur within the high latitudes regions. Ionospheric absorption is then applied, and the gain at both antennas (transmitter and receiver) included. Finally, maps of signal coverage are generated for a specific date, time and frequency. Assessment of IRI model was discussed through comparisons of the prediction with the standard IRI model. Comparisons revealed improvements in foF2 using IRI. The predicted HF signal characteristics have been compared with the observations. The model shows an ability to yield results with good agreement with the observations. Features were reproduced through the model for two periods: one showing the influence of an absorption event, and the other experienced much off great circle propagation. A method of using the output of the nowcast model has been introduced with examples.

The North Polar Layered Deposits (NPLD) of Mars contain a complex stratigraphy that has been suggested to retain a record of past eccentricity- and obliquity-forced climate changes. The surface accumulation rate in the current climate can be constrained by the crater retention age. We scale NPLD crater diameters to account for icy target strength and compare surface age using a new production function for recent small impacts on Mars to the previously used model of Hartmann (2005). Our results indicate that ice is accumulating in these craters several times faster than previously thought, with a 100m diameter crater being completely infilled within centuries. Craters appear to have a diameter-dependent lifetime, but the data also permit a complete resurfacing of the NPLD at similar to 1.5 ka.

The aim of this thesis was to synthesize a functionalized polar conjugated polythiophene that could be (3D-) printed into form-stable structures for bio-interfacing. The material design rationale aimed for a water-processable polymer that had the capability of electronic and ionic conduction, by using a thiophene backbone and oligoethylene side chains. Functionalization of the oligoethylene side chains with carboxylate groups created a polyanion, which allowed for a bio-inspired approach to combine printability and form-stability through formation of complex coacervates. The synthesis of the conjugated monomer and polymer was optimized to provide a more sustainable and material efficient synthesis route. Combined structural analysis with 1H-NMR, FT-IR and UV-vis revealed successful synthesis of the target polymer. Spectro electrochemistry revealed that the polymer was optically and electrochemically active in both the protected and deprotected form. The obtained material is processable from water, and initial tests revealed that crosslinking can be achieved through formation of acid dimers, ionic crosslinks with Ca2+ ions and complex coacervation with a polycation.<br><p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

The present work related to apply hot-melt ink-jet process for imaging at offset lithographic printing form, to utilise a reusable surface for many times and particularly related to validating thermal and ultrasonic erasing processes. This dissertation investigated systematically the role of certain factors towards affecting erasing image area process on print surfaces. Thermal erasing process approved to melt and suck the image area from the surface, the results were adopted by using contact angle measurements and scanning electron microscope. Ultrasonic erasing process permitted to solve the image area by choosing erasing chemistries, influence of selected erasing chemistries on printing surface, and evaluation the process, the results were tested by UV/Vis spectrometer, contact angle, profileometery and visual microscope.<br>Der Fortschritt im Bereich von Charakterisierung und Verständnis für Hot-melt Ink Jet Prozesse zur Bebilderung von Offsetdruckform-Zylindern ist ein Ergebnis dieser Forschung. Die Systematik dieser Arbeit basiert auf einem theoretischen Teil, um einen geeigneten Löschprozess auszuwählen. Der Löschprozess hängt von den Eigenschaften des Hot-melt Ink Jet Materials und der genutzten Aluminiumdruckoberfläche ab. Diese werden systematisch im Labormaßstab experimentell untersucht. Der thermische Prozess wurde einerseits durch Benetzbarkeitsprüfungen und anderseites durch Rasterelektronmikroskopaufnahmen bewertet.Der Ultraschallprozess ist ein nasser Löschprozess. Die Untersuchungen wurden in vier Stufen systematisch durchgeführt - Auswahl vom geeigneten Lösungsmitteln - Einflüsse von ausgewählten Lösungsmitteln auf nicht beschichtete und beschichtete Aluminium platten - Evaluation eines Ultraschalllöschprozesses - Validation eines Löschprozesses; zur Bewertung des Löschprozesses wurden mehrere Druckplattenproben bebildert und gelöscht Die Ergebnisse wurden durch UV/Vis Spektrometer, Kontaktwinkel, Profiliometrie und Visuelle Mikroskopie getestet.

碩士<br>國立臺灣大學<br>漁業科學研究所<br>99<br>The common carp (Cyprinus carpio) required to maintain physiologic and metabolic capabilities when temperature of their habitat varies over a large temperature range 5 °C to 35 °C. At this broad range of temperature, ATP production in energy demanding cells is an important criterion to maintain the common carp. Creatine kinase is an important energy homeostasis enzyme. Muscle-specific creatine kinase (M-CK) catalyses the reversible reaction that converts phosphocreatine and ADP to creatine and ATP and thus provides ATP for muscle contraction. Previously, three common carp CK isoforms (M1-, M2- and M3-CK) were cloned. M1-CK has been suggested to have evolved to become the only CK that functions over the ranges of intracellular pH and body temperature variation that occurs in the common carp. The primary structures of RM-CK (M-CK of homeothermal rabbit) and carp M1-CK share 86% identity. By comparing the differences between RM-CK and M1-CK, and with RM-CK cDNA as template, RM-CK G268N show higher specific activity than wild type at pH 8.0 at 10 °C. This result suggests N268 residue plays an important role in conferring the appropriate 3D structure to M1-CK to function at low temperature. Therefore, we mutated 268 residues to aspartic acid, lysine or leucine and examined their properties. The mutants with polar side chain at residue 268 had higher activity and could maintain their function at low temperature. From the thermal stability, the polar mutants were more stable than non-polar mutants. Examining the structure surface of these mutants, when residue 268 was hydrophilic, it could connect nearby hydrophilic residues to form continuous hydrophilic region. This hydrophilic region could hydrogen bond with water, which then stabilizes the enzyme and results in maintaining activity at low temperature.

Wireless communications are developing quickly. The search for higher data rates is pushing the integration of wideband code-division multiple access (WCDMA) into Global System for Mobile Communications (GSM) and Enhanced Data Rates for GSM Evolution (EDGE) networks. A critical part of the wireless device is the radio transceiver which consists of a receiver and a transmitter. Wireless receivers typically depend on low-intermediate frequency (IF) and direct conversion architectures that convert the received signal directly to baseband frequencies. Wireless transmitters usually employ one of two popular architectures, direct up conversion or polar modulation.It is important to develop a transmitter with a high efficiency and linearity, and with a low system complexity. So, one of the greatest solution is the use of a polar transmitter. A polar transmitter is mainly constituted by two blocks which one is responsible for the phase modulator and the other one for the amplitude modulator. The aim of this dissertation is building a phase modulator for a polar transmitter. This modulator cannot be fully digitally because those architectures have a great power consumption due to the use of multiplexers with a significative number of inputs. Based on this, we decided to follow a mixed signal approach. This modulator is composed by three main blocks: a phase interpolator, a phase signal divider and a sign bit. The crucial cell of this project is the phase interpolator, which is responsible for performing the final RF phase modulation. It receives two digital differential orthogonal signals, thus those signals define which quadrant of unit-circle will be performed. Also, it receives a baseband signal which will select the output phase in the desired quadrant. To select the desired quadrant to perform it was developed a sign bit cell which is responsible for select the input signals of the interpolator. To obtain those four input RF signals it was used a frequency signal divider composed by latches which receive a signal with a frequency two times greater than the required. A high performance phase modulator must have a low phase noise , which implies an increase of power consumption. Based on this, the goal of this project was achieved a great phase resolution with a better power consumption without damaging the output phase per quadrant.In this project, it was achieved a 5-bit resolution, per quadrant, for 360uW power consumption.