Multiple-input multiple-output (MIMO) technology, originated in the 1990s, is an emerging and fast growing area of communication research due to the ability to provide diversity as well as transmission degrees-of-freedom. Recent research focus on MIMO systems has shifted from the point-to-point link to the one-to-many multiuser links due to the ever increasing demand for multimedia-intensive services from users. The downlink of a multiuser transmission is called the broadcast channel (BC) and the reverse many-to-one uplink is termed the multiple access channel (MAC). Early studies in the MIMO BC and the MIMO MAC were mostly information-theoretic in nature. In particular, the characterizations of the capacity regions of the two systems were of primary concerns. The information-theoretic results suggest the optimal uplink detection scheme involves successive interference cancellation while successive application of dirty paper coding at the transmitter is optimal in the downlink channels. Over the past few years, after the full characterizations of the capacity regions, several practical precoders had been suggested to realize the benefits of MIMO multiuser transmission. However, linear precoders such as the zero-forcing (ZF) and the MMSE precoders fall short on the achievable capacity despite their simple structure. Nonlinear precoders such as the ZF dirty paper (ZF-DP) and the the MMSE generalized decision feedback equalizer-type (MMSE-GDFE) precoders demonstrated promising performance but suffered from either restriction on the number of antennas at users, i.e. ZF-DP, or high computational load for the transmit filter, i.e. MMSE-GDFE. An novice MMSE feedback precoder (MMSE-FBP) with low computational requirement was proposed and its performance was shown to come very close to the bound suggested by information theory. In this thesis, we undertake investigation of the causes of the capacity inferiority and come to the conclusion that power control is necessary in a multiuser environment. New schemes that address the power control issue are proposed and their performances are evaluated and compared. Adaptive modulation is an effective and powerful technique that can increase the spectral efficiency in a fading environment remarkably. It works by observing the channel variations and adapts the transmission power and/or rate to counteract the instabilities of the channel. This thesis extends the pioneering study of adaptive modulation on single-input single-output (8180) Gaussian channel to the MIMO BC. We explore various combinations of power and rate adaptions and observe their impact on the system performance. In particular, we present analytical and simulation results on the successiveness of adaptive modulation in maximizing multiuser spectral efficiency. Furthermore, empirical research is conducted to validate its effectiveness in optimizing the overall system reliability.

The limiter is a commonly used device in communication receiving systems to remove the amplitude variations of the received signal, but it is usually observed that limiter degrades the envelope detection performance of a single tone. In this thesis, it is demonstrated that the limiter-generated third harmonic can be used to improve the envelope detection performance of a single tone over that of the linearly processed fundamental. Differences in the probability distributions of the limiter-generated harmonics cause differences in their detection probabilities, which lead to differences in the performance of subsequent envelope detection. Comparison of the envelope detection performance of the limiter-generated third harmonic and the input to the limiter shows a maximum detection probability gain of 1.12 and also error probability gain of 2.4 in linear scale, whereas the fundamental harmonic does not show any practically significant gain. The envelope detection performance of the vector sum of the limiter-generated fundamental and third harmonics is also evaluated. This combination provides better performance than do the individual harmonics, especially for a large clipping parameter of the limiter. The combined harmonics shows a maximum detetction probability gain of 1.15 and error probability gain of 14, over that of the envelope detection performance of a tone without limiter. It is also observed that the envelope detection performance of a tone with limiter-generated higher harmonics shows non-monotonic behaviour as functions of either noise or the limiter-clipping parameter, which is a signature of stochastic resonance. The theoretical results from earlier research on the envelope detection of a single tone embedded in additive white Gaussian noise, both with and without a limiter, are presented and shown to match our simulation results. In previous work when a limiter was used in the envelope detection of a single tone, only the envelope of the fundamental harmonic was considered under very specific conditions. By contrast we also take notice of the limiter-generated higher harmonics and obtain improved envelope detection performance in the detection of a single tone.

Thesis (Ph. D.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Includes bibliographical references (p. 10). / "Physics and Mathematics" -t.p. "TID-4500 (15th Ed.)" -t.p.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 150-155).

Made available in DSpace on 2016-05-17T16:50:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-12. Added 1 bitstream(s) on 2016-05-17T16:54:30Z : No. of bitstreams: 1 000855920.pdf: 373167 bytes, checksum: db4fc619e0ae927d8463d2bfc84a0917 (MD5) / Apresentamos o formalismo de espinores puros da supercorda. Fazemos um estudo sistemático da prescrição para o cálculo de amplitudes em nível árvore nesse formalismo. Discutimos brevemente a supercorda em Ad'S IND 5' x 'S POT. 5' / We present the pure spinor formalism of the superstring. We systematically study the prescription for tree level amplitudes in this formalism. We discuss briefly the superstring in Ad'S IND 5' x 'S POT 5'

Submitted by Beatriz Mendes Tozim null (biatozim@hotmail.com) on 2018-04-03T13:01:20Z No. of bitstreams: 1 defesa doutorado 3.4.18.pdf: 4752539 bytes, checksum: 63bbdb455b4e3467735b5d503b0e38a0 (MD5) / Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2018-04-03T13:21:46Z (GMT) No. of bitstreams: 1 tozim_bm_dr_rcla.pdf: 4689583 bytes, checksum: dceb26a2bb2066d2a1df2f34690b40f3 (MD5) / Made available in DSpace on 2018-04-03T13:21:46Z (GMT). No. of bitstreams: 1 tozim_bm_dr_rcla.pdf: 4689583 bytes, checksum: dceb26a2bb2066d2a1df2f34690b40f3 (MD5) Previous issue date: 2018-03-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A dor lombar (DL) crônica no idoso ocasiona diminuição da resistência e força dos músculos extensores de tronco, flexibilidade, modificações neuromusculares. O exercício terapêutico tem o intuito de manter e ou melhorar as condições físicas ocasionadas pela dor lombar, entre as terapêuticas existe a Protocolo cinesioterapêutico (CIN), que usa exercícios combinados e o método Pilates (MP). OBJETIVO:Analisar o MP e FC na dor, resistência muscular, flexibilidade, força, recrutamento e co-contração dos músculos do tronco de idosas com DL, e comparar com um grupo de ações educativas. MÉTODOS:Participaram do estudo 41 idosas, com DL crônica, divididas em: Grupo Pilates (GP, n=14; 66,71±3,56anos), Grupo CIN (GCIN, n=13; 68,46±4,89anos) e Grupo ações educativas (GAE, n=14; 68,00±4,66anos). A avaliação foi composta pelos testes para: dor (Escala visual analógica), resistência muscular (Teste Biering-Sorensen-TBS), flexibilidade (Sentar e Alcançar, Ângulo Poplíteo), força muscular (FM) e eletromiografia dos músculos tronco (Iliocostal-IL, Multífido- MU, Oblíquo interno- OI). Ao fim da avaliação GP e GCIN realizaram 16 sessões em 8 semanas, e GAE quatro palestras em 8 semanas. A análise estatística usou os testes Shapiro-Wilk, Análise multivariada, analise de Variância Mista e correlação de Pearson (p≤0,05). RESULTADOS: No GP diminuiu a dor (p=0,003), maior resistência muscular (p<0,001) e FM(p=0,003), redução do recrutamento de IL direito durante TBS (p=0,05), co-contração de OI/MU esquerdo (p=0,004), aumento do recrutamento da FM de IL (p<0,001) e MU (p<0,001) direito. O GCIN obteve redução da dor (p=0,014), aumento do tempo de resistência (p=0,003) e FM (p=0,002), e diminuição do recrutamento de IL direito (p=0,008) no TBS e para IL esquerdo na FM (p=0,005). O GAE aumentou co-contração de OI/MU (p=0,02) no TBS e na FM dos músculos IL direito (p=0,007) e esquerdo (p=0,002) e MU direito (p<0,001). CONCLUSÃO: O MP e a FC são importantes na diminuição da dor, aumento do tempo de resistência muscular, FM e redução do recrutamento do IL no TBS de idosos com DL, no teste de FM o IL aumentou o recrutamento. A co-contração diminuiu com o Pilates e aumentou no GAE. / Chronic low back pain (LBP) in the length of the endurance and the strength of the extensor muscles of the trunk, flexibility, neuromuscular modifications. Therapeutic exercise is intended to maintain and improve as the possibilities are caused by LBP, among which there is a kinesiotherapeutic exercise (KT), which uses combined exercise, and Pilates Method (PM). OBJECTIVE: To analyze PM and KT in pain, muscular endurance, flexibility, strength, recruitment and co-contraction of the trunk muscles of elderly women with LBP, and compare with a group educational actions. METHODS:41 elderly women with chronic LBP were divided into: Pilates Group (PG, n = 14, 66.71 ± 3.56 years), KT Group (KTG, n = 13, 68.46 ± 4.89 years) and Group educational actions (EAG, n = 14; 68,00 ± 4,66 years). The tests was evaluated for: pain (Visual Scale Analogy), muscle endurance (Biering-Sorensen test-BST), flexibility (sitting and reaching, popliteal angle), muscle strength (MS) and electromyography of the trunk muscles ( Iliocostal-IL,Multifido- MU, Internal Oblique - OI). The PG and KTG evaluation were performed 8 weeks with16 session, and EAG 8 weeks with 4 lesion. A statistical analysis used the Shapiro-Wilk tests, Multivariate Analysis, Analysis of Variance and Pearson's Key (p≤0.05). RESULTS:PG decreased pain (p = 0.003), higher muscle endurance (p <0.001) and MS (p = 0.003), reduction of right IL recruitment during BST (p = 0.05), IO/MU co-contraction (p = 0.004), increased recruitment of IL FM (p <0.001) and right MU (p <0.001). KTG achieved a reduction in pain (p = 0.014), increased endurance (p = 0.003) and MS (p = 0.002), and decreased recruitment of right IL (p = 0.008) in BST and IL (p = 0.005). EAG increased the co-contraction of OI/MU (p = 0.02) in BST, right (p = 0.007) and left (p = 0.002) IL and right MU (p <0.001) in MS. CONCLUSION: PM and KT are important in reduction pain, increasing muscle strength and endurance, and reduction IL activation in BST, increase MU and IL activation in MS. Cocontraction decreased with PM and increased in EA. / CNPQ: 475806/2013-1

Pure Yang-Mills amplitudes with all external gluons carrying positive helicity, known as all-plus amplitudes, have an especially simple structure. The tree amplitudes vanish and, up to at least two loops, the loop-level amplitudes are related to those of N = 4 super-Yang-Mills (SYM) theory. This makes all-plus amplitudes a useful testing ground for new methods of simplifing more general classes of amplitudes. In this thesis we consider three new approaches, focusing on the structure before integration. We begin with the planar (leading-colour) sector. A D-dimensional local-integrand presentation, based on four-dimensional local integrands developed for N = 4 SYM, is developed. This allows us to compute the planar six-gluon, two-loop all-plus amplitude. Its soft structure is understood before integration, and we also perform checks on collinear limits. We then proceed to consider subleading-colour structures. A multi-peripheral colour decomposition is used to find colour factors based on underlying tree-level amplitudes via generalised unitarity cuts. This allows us to find the integrand of the full-colour, two-loop, five-gluon all-plus amplitude. Tree-level BCJ relations, satisfied by amplitudes appearing in the cuts, allow us to deduce all the necessary non-planar information for the full-colour amplitude from known planar data. Finally, we consider representations satisfying colour-kinematics duality. We discuss obstacles to finding such numerators in the context of the same five-gluon amplitude at two loops. The obstacles are overcome by adding loop momentum to our numerators to accommodate tension between the values of certain cuts and the symmetries of certain diagrams. Control over the size of our ansatz is maintained by identifying a highly constraining, but desirable, symmetry property of our master numerator.

Le Disjoncteur Différentiel Résiduel (DDR) doit garantir la continuité de service ce qui signifie qu'aucun défaut autre que ceux pouvant mettre l'utilisateur en danger ne doivent faire déclencher le produit pour éviter soit des désagréments (non alimentation du congélateur) soit une perte financière (non exploitation d'une installation photovoltaïque).La fonction mesure est composée de :- Un tore pour la mesure du courant résiduel, il réalise naturellement la somme des courants entrant et sortant de l'installation- Une plaquette de mise en forme (filtrage)- Un actionneur, le relais polarisé qui fixe le seuil du dispositif (par sa puissance de déclenchement et fournit une énergie mécanique pour mettre l'installation hors tension.Ces déclenchements non désirés proviennent des défauts de la chaine de mesure. Nous pouvons en citer 3 principales causes :- Courant de fuite à la terre trop important (perturbation réseau mode commun)- Champs magnétiques rayonnés (courant passant dans le primaire du tore)- Equilibrage du tore (mode différentiel) (courant passant dans le primaire du tore)Les surtensions atmosphériques étant considérées comme étant les perturbations les plus critiques, les travaux faits durant cette thèse reposent sur ce phénomène. Toute la problématique est basée sur la manière avec laquelle le disjoncteur différentiel répond face à ces perturbations. Une bonne compréhension de sa réaction dans de tels cas s'avère nécessaire. Les objectifs visés par cette étude sont de :- Trouver un modèle temporel du phénomène de foudre- Mettre en évidence les différentes phases de fonctionnement engendré lors de la réponse d'un DDR à un coup de foudre- Etablir un modèle comportemental du DDR adapté à chaque phase- Mettre en évidence la cause des déclenchements intempestifs- Proposer des solutions permettant a nos produits de ne pas déclencher de façon intempestives et fiabiliser ainsi leur fonctionnement- Diminuer par conséquent les retours clients / The Residual Current Device (RCD) must ensure the continuity of service which means that no default other than those that can put the user at risk should make the product trigger, to avoid any inconvenience (freezer not supplied) or a financial loss (non-operation of a photovoltaic). The measurement function is made up of:- A torus for measuring the residual current, it naturally carries the sum of currents entering and exiting the installation- A plate shaping (filtering)- An actuator, the polarized relay which sets the threshold of the device (through its power of initiation) and provides mechanical energy to turn off power supply.These false triggering are caused by defaults initiated among the measurement chain. We can cite three main reasons:- Residual current too high (over-voltages on electrical network by common mode)- Radiated Magnetic Fields (current through the primary circuit of the torus)- Balancing the torus (differential mode) (current through the primary circuit of the torus)As the atmospheric over-voltages are considered to be the most critical disturbances, they will appear as the principal subject of this thesis. The main issue is the behavior of the RCD facing a lightning stroke. So, a well understanding of the manner that it will respond in such situations is necessary. The objectives of this study are to:- Establish a temporal model of lightning stroke- Highlight the different working phases in front of a lightning stroke- Establish a RCD's behavioral model adapted to every phase- Highlight the causes of unwanted triggers- Propose solutions enabling our products to not trigger by default and so improve the reliability of their functioning- Reduce customer returns

O objetivo deste estudo foi comparar as adaptações neuromusculares e morfológicas de treinamentos de força realizados com amplitudes parcial e total de movimento nos músculos flexores de cotovelo e extensores de joelho. Participaram do estudo 41 voluntários do sexo masculino destreinados em força (23,78 ± 3,27 anos), divididos em três grupos: PS-TI (Parcial Superior – Total Inferior; n=14), TS-PI (Total Superior – Parcial Inferior; n=16) e GC (Grupo Controle; n=11). O grupo PS-TI realizou o treinamento de flexão de cotovelo em amplitude parcial (40°- 90°) e de extensão de joelho em amplitude total (90° - 0°). O grupo TS-PI realizou o treinamento de flexão de cotovelo em amplitude total (0° - 120°) e de extensão de joelho em amplitude parcial (60° - 30°). Os sujeitos treinaram duas vezes por semana por um período de 12 semanas. O GC não realizou o treinamento. Antes e após o período de treinamento, os sujeitos foram avaliados em parâmetros relacionados à força muscular dinâmica, resistência muscular, pico de torque isocinético, pico de torque isométrico em diferentes ângulos, ativação muscular dinâmica e isométrica em diferentes ângulos e hipertrofia muscular. Para a força muscular dinâmica, avaliada pelo teste de uma repetição máxima (1RM), o grupo TS-PI teve incrementos de 1RM de flexão de cotovelo (29,37%) maiores que PS-TI (18,42%) (p<0,001). Ainda, o grupo PS-TI teve incrementos de 1RM de extensão de joelho (25,69%) maiores que TS-PI (15,06%) (p=0,038). A resistência muscular, avaliada pelo teste de 60% de 1RM absoluto, mostrou, para a flexão de cotovelo e extensão de joelho, que o grupo que treinou em amplitude total realizou um número maior de repetições do que o que treinou em amplitude parcial o exercício avaliado. Não foram encontradas diferenças nos incrementos de picos de torque isocinético e isométrico em diferentes ângulos entre os grupos PS-TI e TS-PI na flexão de cotovelo e extensão de joelho. Não foram encontrados incrementos significativos de ativação muscular, avaliada durante os testes isocinéticos e isométricos em diferentes ângulos. Foram encontrados incrementos significativos de hipertrofia, avaliada pela espessura muscular, nos músculos flexores de cotovelo, sem diferença entre os grupos PS-TI e TS-PI. Quanto à espessura muscular nos extensores de joelho, o grupo PS-TI teve maiores incrementos quando comparado a TS-PI no somatório de todos os músculos extensores de joelho (6,74% vs. 5,02%) (p=0,001) e no somatório de três diferentes pontos avaliados no músculo vasto lateral (5,20% vs 3,37%) (p=0,033). Assim, todas as diferenças encontradas neste estudo foram a favor do treinamento em amplitude total de movimento, ainda que o grupo que treinou o exercício em amplitude parcial de movimento tenha treinado com cargas significativamente mais elevadas durante todo período de treinamento (PS-TI: 47,94% mais elevada na flexão de cotovelo; TS-PI: 61,32% mais elevada na extensão de joelho). Dessa forma, pode-se concluir que o treinamento de força em amplitude total de movimento causa melhores adaptações neuromusculares e morfológicas, sendo mais efetivo para incrementos de força, resistência e hipertrofia muscular de flexores de cotovelo e extensores de joelho em homens jovens. / The purpose of this investigation was to compare neural and morphological adaptations of a partial range of motion versus a full range of motion strength training in the elbow flexors and knee extensors. Forty-one untrained men (23.78 ± 3.27 years) were divided into three groups: PU-FL (Partial Upper – Full Lower; n=14), FU-PL (Full Upper – Partial Lower; n=16) and CG (Control Group; n=11). The PU-FL group during the training performed elbow flexion with partial range of motion (40° - 90°) and performed knee extension with full range of motion (90° - 0°). The FU-PL group during the training performed elbow flexion with full range of motion (0° - 120°) and performed knee extensor with partial range of motion (60° - 30°). The subjects trained two times per week during 12 weeks. The CG did not train. Before and after training period, subjects were evaluated in parameters related to dynamic muscle strength, muscle endurance, isokinetic peak torque, isometric peak torque at different angles, dynamic and isometric (at different angles) muscle activation and muscle hypertrophy. For the dynamic muscle strength, evaluated by one repetition maximum (1RM) test, the increase in 1RM of the elbow flexion for the FU-PL group (29.37%) was greater than PU-FL group (18.42%) (p<0.001). Moreover, the increase in 1RM of the knee extension for the PU-FL group (25.69%) was greater than FU-PL (15.06%) (p=0.038). The muscle endurance, evaluated by 60% of 1RM test with absolute load in the elbow flexion and knee extension, showed the group that trained the exercise with full range of motion performed a greater number of repetitions than those trained the evaluated exercise with partial range of motion. No differences were observed between PU-FL and FU-PL groups for the increase for isokinetic or isometrics, at different angles, peaks torque in elbow flexion and knee extension. No significant findings were observed for muscle activation measured during isokinetic and isometrics tests. There were significant increases on muscle hypertrophy, evaluated by muscle thickness, of the elbow flexors, but no difference were observed between PU-FL and FU-PL groups. For the muscle thickness of the knee extensors, the increase for the PU-FL group was greater than FU-PL group at sum of all knee extensors muscles (6.74% vs. 5.02%) (p=0.001) and at sum of three different points evaluated in the vastus lateralis muscle (5.20% vs. 3.37%) (p=0.033). Thereby, all the differences found in this investigation were in favor of full range of motion training, despite the group that trained with partial range of motion have been used higher loads throughout the training period (PU-FL: 47.94% higher in elbow flexion; FU-PL: 61.32% higher in knee extension). Thus, we can conclude that strength training with full range of motion causes better neural and morphological adaptations, being more effective for increase in strength, endurance and muscle hypertrophy in the elbow flexors and knee extensors of the young men.