Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-03-09T13:27:58Z No. of bitstreams: 1 ALMIR_JOSE_HENKES_TES.pdf: 9938064 bytes, checksum: 8470f9a982c6e56ac07eef34336431ec (MD5) / Approved for entry into archive by Tatiana Lopes (tatiana.lopes@pucrs.br) on 2018-03-13T11:52:50Z (GMT) No. of bitstreams: 1 ALMIR_JOSE_HENKES_TES.pdf: 9938064 bytes, checksum: 8470f9a982c6e56ac07eef34336431ec (MD5) / Made available in DSpace on 2018-03-13T12:00:25Z (GMT). No. of bitstreams: 1 ALMIR_JOSE_HENKES_TES.pdf: 9938064 bytes, checksum: 8470f9a982c6e56ac07eef34336431ec (MD5) Previous issue date: 2017-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This study aimed to evaluate, in vitro, through the fracture strength testing, the influence of a fiberglass post position position, intracanal or horizontally transfixed, inserted in endodontically treated molars with MOD preparations and restored with composite resin and evaluate the fracture pattern after the mechanical test; and evaluate, through the fracture strength testing, the influence of a horizontally transfixed fiberglass post, inserted in endodontically treated molars with MOD cavity preparation and restored with Bulk Fill resins and to evaluate the fracture pattern after the mechanical test. In the first test, fifty extracted healthy molars were embedded in acrylic resin and divided into 5 groups (n = 10): G1(H) - sound; G2(CP) - cavity preparation (MOD) + endodontic treatment (E); G3 (R) - (MOD) + E + Z250 composite resin restoration (RS); G4- (RFP) (MOD) + E + fiberglass post into root canal + RS; G5 (FT) - (MOD) + E + fiberglass post horizontally transfixed + R; In the second test, ninety extracted molars were embedded in acrylic resin and divided into 9 groups (n = 10): G1) Sound (H); G2)cavity preparation (MOD); G3) MOD + root canal treatment (E); G4) E + Bulk fil composite resin (BF); G5) E + Bulk fill flow composite resin (BFF) + Z250 composite resin (250); G6) E + Z250; G7) E + transfixed fiberglass post (TP) + Z250 (Z250P); G8)E +TP+BF (BFP); G9) E + TP + BFF + Z250 (BFFP). The MOD cavity preparations were standardized with 2/3 width of the vestibular-lingual distance, with reference to the tip of the respective cusps, and occlusal-gingival depth of 4 mm, remaining 2 mm above the cement-cementum limit. The root canal treatments were performed in all groups, except for H group. Afterwards, the teeth were submitted to the fracture strength testing in a universal testing machine. After the mechanical test, the teeth were visually inspected to classify the fracture type as: pulp chamber floor (non-recoverable) or cusps (recoverable). Means (Newtons) followed by the same letter do not present statistical difference for ANOVA and Tukey?s test (p> 0.05): and for the first test, group (H) 5558N A; (E) 950N C; (R) 1715N C; (FC) 1723N C; (FT) 2621N B. The predominant pattern of fracture was in cusps, and for the second test, it was (H) 3930N a; (MOD) 957.3N d; (E) 611.2N d; (BF) 1103.3N d; (BFF) 978.3N d; (Z250) 1359.8 d; (Z250P) 2525N b; (BFP) 1891.4N bc; (BFFP) 2031.8N bc. The predominant failure mode was in pulp chamber floor (52.5%). The use of a horizontally transfixed fiberglass post (FT) in the first test showed the best fracture resistance recovery compared to the (E) group. The use of a fiberglass post into root canal, statistically, did not promote higher resistance to fracture (1723N) compared to the group restored with composite resin only (1715N). In the second test, Inserting a fiberglass post horizontally in molars endodontically treated and restoring with composite resins, Bulk Fill or conventional Z250, allowed higher fracture resistance than groups restored without post. The use of a fiberglass post decreased the occurrence of pulpal chamber floor fractures in endodontically treated molars. / Este estudo teve por objetivo avaliar, in vitro, atrav?s do ensaio de resist?ncia ? fratura, a influ?ncia do posicionamento do pino de fibra de vidro, intracanal ou transfixado horizontalmente, inserido em molares endodonticamente tratados com preparos MOD e restaurados com resina composta, e avaliar o padr?o de fratura ap?s o ensaio mec?nico; e avaliar, in vitro, atrav?s do ensaio de resist?ncia ? fratura, a influ?ncia do pino de fibra de vidro transfixado horizontalmente, inserido em molares endodonticamente tratados com preparos MOD e restaurados com resinas Bulk Fill, e avaliar o padr?o de fratura ap?s o ensaio mec?nico. No primeiro ensaio, cinquenta molares h?gidos extra?dos foram embutidos em resina acr?lica e divididos em 5 grupos (n=10): h?gidos (H); preparo cavit?rio (MOD) + tratamento endod?ntico (E); preparo cavit?rio (MOD) + tratamento endod?ntico + restaura??o com resina composta Z250 (R); preparo cavit?rio (MOD) + tratamento endod?ntico + pino de fibra vidro no conduto + restaura??o com resina composta Z250 (FC); preparo cavit?rio (MOD) + tratamento endod?ntico pino de fibra vidro transfixado + restaura??o com resina composta Z250 (FT). No segundo ensaio, noventa molares h?gidos extra?dos foram inclu?dos em resina acr?lica e divididos em 9 grupos (n=10): G1) H?gidos (H); G2) preparo cavit?rio MOD (MOD); G3) (MOD) + tratamento endod?ntico (E); G4) E + restaura??o com resina Bulk fil (BF); G5) E + Bulk fill Flow + Z250 (BFF); G6) preparo cavit?rio (MOD) + tratamento endod?ntico + restaura??o com resina composta Z250 (Z250); G7) E + pino de vidro transfixado (TP) + Z250 (Z250P); G8) E+ TP + Bulk fill (BFP); G9) E+ TP + Bulk fill Flow + Z250 (BFFP). Os preparos cavit?rios MOD foram padronizados com largura de 2/3 da dist?ncia vest?bulo-lingual, tendo como refer?ncia a ponta das respectivas c?spides, e profundidade ocluso-gengival de 4mm, permanecendo 2mm acima do limite amelocement?rio. Foram realizados tratamentos endod?nticos em todos os grupos, exceto para o grupo dos dentes h?gidos. Ap?s, os dentes foram submetidos ao ensaio de resist?ncia ? fratura em uma m?quina de ensaio universal. Ap?s realiza??o dos ensaios, os dentes foram inspecionados quanto ao tipo de fratura e classificados em: fratura em assoalho pulpar (n?o recuper?vel) ou c?spide (recuper?vel). M?dias seguidas de mesma letra n?o apresentam diferen?a estat?stica para ANOVA e Tukey (p>0,05): sendo para o primeiro ensaio, grupo (H) 5558NA; (E) 950NC; (R) 1715NC; (FC) 1723NC; (FT) 2621NB. O padr?o predominante de fratura foi em c?spide, e para o segundo ensaio, foi (H) 3930Na; (MOD) 957,3Nd; (E) 611,2Nd; (BF)1103,3Nd; (BFF)978,3Nd;(Z250)1359,8d;(Z250P)2525Nb;(BFP)1891,4Nbc;(BFFP) 2031,8Nbc. O padr?o de falha de fratura foi de 52,5% em assoalho da c?mara pulpar. A utiliza??o de um pino de fibra de vidro transfixado horizontalmente (FT) no primeiro ensaio, apresentou o melhor resultado de recupera??o da resist?ncia ? fratura comparado ao grupo (E). A utiliza??o de um pino de fibra de vidro no conduto, estatisticamente, n?o obteve maior resist?ncia ? fratura (1723N) comparado com o grupo restaurado somente com resina composta, (1715N). No segundo ensaio, um pino de fibra de vidro transfixado horizontalmente em cavidades MOD com endodontia e restaurar com resinas compostas Bulk Fill ou convencional Z250, permitiu maiores valores de resist?ncia ? fratura quando comparados ? n?o utiliza??o do pino. O uso do pino de fibra de vidro diminuiu a ocorr?ncia de fraturas de assoalho da c?mara pulpar em molares tratados endodonticamente e restaurados com resinas compostas do tipo Bulk Fill e convencional.

No description available.

<p>The purpose of this study was to develop an analytical model that could be used by the designers of a rotary feeding and cutting system (RFCS) to identify the power demand of the RFCS with limited or no required field or laboratory data. Two separate RFCS were investigated, incorporated with either a low-speed cutting process (LSCP) or a high-speed cutting process (HSCP). The results from the laboratory and field trials were used to create and validate the analytical model.</p> <p>Laboratory tests were completed with the LSCP RFCS and these concluded that counter-knife sharpness, serrations and bevel angle all had significant effects on the specific energy required by the LSCP RFCS when processing cereal straw and alfalfa. The specific energy required by the LSCP RFCS, while processing cereal straw, increased by 0.35 kWâh/tonne (or 96%) when the sharpness of the counter-knives decreased from 0.13 to 0.63 mm (where the sharpness was recorded by the leading-edge-width of the counter-knives). With the same decrease in sharpness, the specific energy required by the LSCP RFCS while processing alfalfa increased by 0.04 kWâh/tonne (or 32%). The specific energy required by the LSCP RFCS while processing cereal straw with sharp counter-knives (counter-knives with a leading edge width of 0.13 mm) increased by 0.11 kWâh/tonne (or 51%) when serrated counter-knives were used instead of un-serrated counter-knives. However, counter-knife serrations did not have a significant effect on the specific energy demand of the LSCP RFCS when sharp counter-knives were used to process alfalfa. The increase in bevel angle from 15 to 90&#x00B0; caused the specific energy required to process cereal straw and alfalfa to approximately triple. The moisture content of alfalfa also had a significant effect on the specific energy required to process alfalfa with the LSCP RFCS. The specific energy demand of the LSCP RFCS was at a maximum when alfalfa at a moisture content of 53% on a wet basis (w.b.) was processed and decreased slightly (approximately 0.04 kWâh/tonne or 10%) when dryer and wetter alfalfa was processed.</p> <p>Field tests were completed with the HSCP RFCS and it was concluded that in general, there was a direct relationship between the specific energy required by the HSCP RFCS and the moisture content of the straw, counter-knife engagement and throughput. Further, it was also concluded that the specific energy requirements of the HSCP RFCS were more sensitive to counter-knife engagement when higher moisture content straw was processed. Depending on the type of chopper used, the specific energy required by the HSCP RFCS increased anywhere from 0.15 to 0.77 kWâh/tonne (or 22 to 61%) when the counter-knife engagement was increased from 0 to 100% (or fully removed to fully engaged). Again, depending on the type of chopper used, when the moisture content of the straw processed by the chopper increased from approximately 7 to 25% w.b. the specific energy required by the chopper increased by 0.14 to 0.96 kWâh/tonne (or 28 to 84%). The effect of throughput on the specific energy demand of the HSCP RFCS was dependent on the type of chopper used. For one of the choppers, an increase in throughput from 10.5 to 13.5 tonne/h caused the specific energy required by the HSCP RFCS to increase by 0.24 kWâh/tonne (or 35%); however for a different chopper, an increase in throughput from 12 to 13 tonne/h caused the specific energy demand of the HSCP RFCS to decrease by 0.16 kWâh/tonne (or 19%).</p> <p>The analytical model was validated using a subset of the data that were collected while employing each cutting device under field conditions and the data collected with the use of a custom-designed material properties test stand. The output of the analytical model fell within the 95% confidence interval of the measured power demand for each of the rotary feeding and cutting systems, and the analytical model was therefore deemed sufficiently accurate.</p> <p>Based on the analytical model, the total power demand of both the LSCP and HSCP rotary feeding and cutting systems was largely attributed to the power required to transport plant material. Further, the power required to transport the plant material along the sides of the counter-knives was much greater than the power required to transport the plant material along the rotor bed and along the leading edge of the tines. Because of the excessive power required to transport plant material along the sides of the counter-knives, three techniques were identified as potential strategies to decrease the power demand of the RFCS. The first technique involved removing half of the tines from the RFCS, and modifying the remaining tines to decrease the amount of plant material that is entrapped between sides of the counter-knives and the tines. The second technique involved coating the inside surface of the tines with a baked Teflon, to decrease the coefficient of friction between the plant material and the RFCS. The third technique involved reshaping the counter-knives, to decrease the surface area over which plant material was transported along the side of the counter-knives. According to the analytical model, employing any of the three techniques would result in the total power demand of the RFCS to decrease by 15 to 26%. </p> <p>For the HSCP RFCS, a stochastic model was developed to identify which of the four choppers tested during field trials would have the best performance when subjected to the same operating conditions. The chopper with the best performance was the WR chopper as its use resulted in the minimum geometric mean length of material exiting the combine harvester while also consuming the least amount of specific energy.</p>

<p>The purpose of this study was to develop an analytical model that could be used by the designers of a rotary feeding and cutting system (RFCS) to identify the power demand of the RFCS with limited or no required field or laboratory data. Two separate RFCS were investigated, incorporated with either a low-speed cutting process (LSCP) or a high-speed cutting process (HSCP). The results from the laboratory and field trials were used to create and validate the analytical model.</p> <p>Laboratory tests were completed with the LSCP RFCS and these concluded that counter-knife sharpness, serrations and bevel angle all had significant effects on the specific energy required by the LSCP RFCS when processing cereal straw and alfalfa. The specific energy required by the LSCP RFCS, while processing cereal straw, increased by 0.35 kWâh/tonne (or 96%) when the sharpness of the counter-knives decreased from 0.13 to 0.63 mm (where the sharpness was recorded by the leading-edge-width of the counter-knives). With the same decrease in sharpness, the specific energy required by the LSCP RFCS while processing alfalfa increased by 0.04 kWâh/tonne (or 32%). The specific energy required by the LSCP RFCS while processing cereal straw with sharp counter-knives (counter-knives with a leading edge width of 0.13 mm) increased by 0.11 kWâh/tonne (or 51%) when serrated counter-knives were used instead of un-serrated counter-knives. However, counter-knife serrations did not have a significant effect on the specific energy demand of the LSCP RFCS when sharp counter-knives were used to process alfalfa. The increase in bevel angle from 15 to 90&#x00B0; caused the specific energy required to process cereal straw and alfalfa to approximately triple. The moisture content of alfalfa also had a significant effect on the specific energy required to process alfalfa with the LSCP RFCS. The specific energy demand of the LSCP RFCS was at a maximum when alfalfa at a moisture content of 53% on a wet basis (w.b.) was processed and decreased slightly (approximately 0.04 kWâh/tonne or 10%) when dryer and wetter alfalfa was processed.</p> <p>Field tests were completed with the HSCP RFCS and it was concluded that in general, there was a direct relationship between the specific energy required by the HSCP RFCS and the moisture content of the straw, counter-knife engagement and throughput. Further, it was also concluded that the specific energy requirements of the HSCP RFCS were more sensitive to counter-knife engagement when higher moisture content straw was processed. Depending on the type of chopper used, the specific energy required by the HSCP RFCS increased anywhere from 0.15 to 0.77 kWâh/tonne (or 22 to 61%) when the counter-knife engagement was increased from 0 to 100% (or fully removed to fully engaged). Again, depending on the type of chopper used, when the moisture content of the straw processed by the chopper increased from approximately 7 to 25% w.b. the specific energy required by the chopper increased by 0.14 to 0.96 kWâh/tonne (or 28 to 84%). The effect of throughput on the specific energy demand of the HSCP RFCS was dependent on the type of chopper used. For one of the choppers, an increase in throughput from 10.5 to 13.5 tonne/h caused the specific energy required by the HSCP RFCS to increase by 0.24 kWâh/tonne (or 35%); however for a different chopper, an increase in throughput from 12 to 13 tonne/h caused the specific energy demand of the HSCP RFCS to decrease by 0.16 kWâh/tonne (or 19%).</p> <p>The analytical model was validated using a subset of the data that were collected while employing each cutting device under field conditions and the data collected with the use of a custom-designed material properties test stand. The output of the analytical model fell within the 95% confidence interval of the measured power demand for each of the rotary feeding and cutting systems, and the analytical model was therefore deemed sufficiently accurate.</p> <p>Based on the analytical model, the total power demand of both the LSCP and HSCP rotary feeding and cutting systems was largely attributed to the power required to transport plant material. Further, the power required to transport the plant material along the sides of the counter-knives was much greater than the power required to transport the plant material along the rotor bed and along the leading edge of the tines. Because of the excessive power required to transport plant material along the sides of the counter-knives, three techniques were identified as potential strategies to decrease the power demand of the RFCS. The first technique involved removing half of the tines from the RFCS, and modifying the remaining tines to decrease the amount of plant material that is entrapped between sides of the counter-knives and the tines. The second technique involved coating the inside surface of the tines with a baked Teflon, to decrease the coefficient of friction between the plant material and the RFCS. The third technique involved reshaping the counter-knives, to decrease the surface area over which plant material was transported along the side of the counter-knives. According to the analytical model, employing any of the three techniques would result in the total power demand of the RFCS to decrease by 15 to 26%. </p> <p>For the HSCP RFCS, a stochastic model was developed to identify which of the four choppers tested during field trials would have the best performance when subjected to the same operating conditions. The chopper with the best performance was the WR chopper as its use resulted in the minimum geometric mean length of material exiting the combine harvester while also consuming the least amount of specific energy.</p>

No description available.

In this dissertation we consider cooperative communication systems with relay conferencing, where the relays own the capabilities to talk to their counterparts via either wired or wireless out-of-band links. In particular, we focus on the design of conferencing protocols incorporating the half-duplex relaying operations, and study the corresponding capacity upper and lower bounds for some typical channels and networks models, including the diamond relay channels (one source-destination pairs and two relays), large relay networks (one source-destination pairs and N relays), and interference relay channels (two source-destination pairs and two relays). First, for the diamond relay channels, we consider two different relaying schemes, i.e., simultaneous relaying (for which the two relays transmit and receive in the same time slot) and alternative relaying (for which the two relays exchange their transmit and receive modes alternatively over time), for which we obtain the respective achievable rates by using the decode-and-forward (DF), compress-and-forward (CF), and amplify-and-forward (AF) relaying schemes with DF and AF adopted the conferencing schemes. Moreover, we prove some capacity results under some special conditions. Second, we consider the large relay networks, and propose a "p-portion" conferencing scheme, where each relay can talk to the other "p-portion" of the relays. We obtain the DF and AF achievable rates by using the AF conferencing scheme. It is proved that relay conferencing increases the throughput scaling order of the DF relaying scheme from O(log(log(N ))) for the case without conferencing to O(log(N )); for the AF relaying scheme, it achieves the capacity upper bound under some conditions. Finally, we consider the two-hop interference relay channels, and obtain the AF achievable rates by adopting the AF conferencing scheme and two different decoding schemes at the destination, i.e., single-user decoding and joint decoding. For the derived joint source power allocation and relay combining problem, we develop some efficient iterative algorithms to compute the AF achievable rate regions. Moreover, we compare the achievable degree-of-freedom (DoF) performance of these two decoding schemes, and show that single-user decoding with interference cancellation at the relays is optimal.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-04-26T20:00:09Z No. of bitstreams: 1 TahyaraBarbalhoFontoura_DISSERT.pdf: 7478783 bytes, checksum: b6e15d5fd03c19ed46e5a9a91fa42f46 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-29T20:14:41Z (GMT) No. of bitstreams: 1 TahyaraBarbalhoFontoura_DISSERT.pdf: 7478783 bytes, checksum: b6e15d5fd03c19ed46e5a9a91fa42f46 (MD5) / Made available in DSpace on 2016-04-29T20:14:41Z (GMT). No. of bitstreams: 1 TahyaraBarbalhoFontoura_DISSERT.pdf: 7478783 bytes, checksum: b6e15d5fd03c19ed46e5a9a91fa42f46 (MD5) Previous issue date: 2015-02-20 / Nas ?ltimas d?cadas v?rios trabalhos v?m sendo realizados no sentido de compreender o comportamento dos solos com cimenta??o (natural ou artificial) entre as part?culas. As areias, objeto de estudo desse trabalho, geralmente apresentam boa capacidade de suporte. Entretanto, muitas vezes se faz necess?ria a realiza??o de melhoramento do solo, para aumento da capacidade de suporte est?tica ou mesmo de se considerar o efeito da cimenta??o natural que ocorre em algumas areias. Para isso, ? necess?rio que se compreenda o comportamento mec?nico dos solos cimentados. O objetivo geral deste estudo foi descrever o comportamento tens?o - deforma??o - resist?ncia de uma areia origin?ria de Dunas de Natal cimentada artificialmente atrav?s de ensaios de compress?o simples e ensaios de compress?o triaxial drenados. Foi avaliada a influ?ncia do teor de cimento, da umidade de moldagem, do ?ndice de vazios e da tens?o confinante sobre a resist?ncia e verificada a validade do uso do fator vazios/cimento na estimativa da resist?ncia ? compress?o simples, da resist?ncia ao cisalhamento em condi??es drenadas e do comportamento tens?o-deforma??o. As amostras dos ensaios de compress?o simples foram moldadas com diferentes teores de umidade de moldagem (6%, 9% e 12%), diferentes teores de cimento (2,5%; 5,0%; 7,5% e 10%) e ?ndice de vazios de 0,6. Nos ensaios de compress?o triaxial, todas as amostras foram moldadas na umidade de 6%, com tr?s ?ndices de vazios (0,6; 0,7 e 0,8) e quatro teores de cimento (0,0%; 2,5%; 5,0% e 7,5%), sendo rompidas sob diferentes tens?es confinantes (50, 100, 200 e 300 kPa). O agente cimentante utilizado foi o Cimento Portland de Alta resist?ncia inicial resistente aos sulfatos (CP-V ARI ? RS). Concluiu-se que, a resist?ncia a compress?o simples cresce com o aumento do teor de cimento e com a diminui??o da umidade de moldagem. Quanto a resist?ncia ao cisalhamento, verificou-se que esta aumenta com o aumento da quantidade de cimento e com a diminui??o do ?ndice de vazios. Percebeu-se ainda que a varia??o nos valores de ?ngulo de atrito se mostrou praticamente negligenci?vel quando comparado com a varia??o do intercepto coesivo. Por fim, foi verificado que o fator vazios/cimento mostrou-se ser um par?metro muito eficaz e confi?vel na previs?o do comportamento da areia de Natal para dosagem de solo-cimento. / In recent decades a number of studies have been conducted in order to understand the behavior of soil with cementation (natural or artificial) between particles. The sands studied here generally exhibit good bearing capacity. However, it is often necessary to improve the soil to increase static support capacity or even to consider the effect of natural cementing that occurs in some sands. To that end, it is important to understand the mechanical behavior of cemented soils. The general aim of this study was to describe stress-strain-strength behavior of artificially-cemented sand from the Dunes of Natal, Brazil by means of unconfined compression and drained triaxial compression tests. The influence of cement content, molding moisture, void ratio and confining stress on strength was assessed and the validity of using the void/cement factor in estimating unconfined compressive strength, shear strength in drained conditions and stress-strain behavior was determined. Unconfined compression test samples were molded using different molding moisture levels (6%, 9% and 12%), different cement content (2.5%; 5.0%; 7.5% and 10%) and a void ratio of 0.6. In triaxial compression tests, all the samples were molded in 6% moisture with three void ratios (0.6; 0.7 and 0.8) and four cement contents (0.0%; 2.5%; 5.0% and 7.5%), and rupture occurred under different confining stresses (50, 100, 200 and 300 kPa). The cementing agent used was high-early-strength Portland cement, with sulphate resistance (CP-V ARI ? RS). It was concluded that unconfined compressive strength rises with an increase in cement content and a decline in molding moisture. It was found that shear strength increases with a rise in the amount of cement and a decrease in void ratio. It was also observed that the variation in friction angle values was practically negligible when compared to the change in cohesion intercept. Finally, it was found that the void/cement factor was a very effective and reliable parameter for predicting the behavior of Natal Sand in order to determine the soil-cement dosage.

Made available in DSpace on 2014-12-17T14:55:31Z (GMT). No. of bitstreams: 1 JoseMB_capa_ate_pag12.pdf: 7494669 bytes, checksum: 353155cd86e106a661e9f32c5ead7aba (MD5) Previous issue date: 2002-06-21 / ln this work the implementation of the SOM (Self Organizing Maps) algorithm or Kohonen neural network is presented in the form of hierarchical structures, applied to the compression of images. The main objective of this approach is to develop an Hierarchical SOM algorithm with static structure and another one with dynamic structure to generate codebooks (books of codes) in the process of the image Vector Quantization (VQ), reducing the time of processing and obtaining a good rate of compression of images with a minimum degradation of the quality in relation to the original image. Both self-organizing neural networks developed here, were denominated HSOM, for static case, and DHSOM, for the dynamic case. ln the first form, the hierarchical structure is previously defined and in the later this structure grows in an automatic way in agreement with heuristic rules that explore the data of the training group without use of external parameters. For the network, the heuristic mIes determine the dynamics of growth, the pruning of ramifications criteria, the flexibility and the size of children maps. The LBO (Linde-Buzo-Oray) algorithm or K-means, one ofthe more used algorithms to develop codebook for Vector Quantization, was used together with the algorithm of Kohonen in its basic form, that is, not hierarchical, as a reference to compare the performance of the algorithms here proposed. A performance analysis between the two hierarchical structures is also accomplished in this work. The efficiency of the proposed processing is verified by the reduction in the complexity computational compared to the traditional algorithms, as well as, through the quantitative analysis of the images reconstructed in function of the parameters: (PSNR) peak signal-to-noise ratio and (MSE) medium squared error / Neste trabalho ? apresentada a implementa??o do algoritmo SOM (Self Organizing Maps) ou rede neural de Kohonen na forma de estruturas hier?rquicas, aplicadas ? compress?o de imagens. O objetivo desta abordagem ? desenvolver um algoritmo SOM Hier?rquico com estrutura est?tica e um outro com estrutura din?mica para gerar codebooks (livros de c?digos) no processo de Quantiza??o Vetorial (VQ) da imagem; reduzindo o tempo de processamento e obtendo uma boa taxa de compress?o de imagens com um comprometimento m?nimo da qualidade em rela??o ? imagem original. As duas redes neurais auto-organiz?veis aqui desenvolvidas, foram denominadas de HSOM, para caso est?tico e de DHSOM, para caso din?mico. Na primeira, a estrutura hier?rquica ? previamente definida e na segunda essa estrutura se desenvolve de forma autom?tica de acordo com regras heur?sticas propostas neste trabalho, que exploram os dados do conjunto de treinamento sem que haja necessidade de utiliza??o de par?metros externos. As regras heur?sticas determinam a din?mica de crescimento da rede, o crit?rio de poda de ramifica??es da rede, a flexibilidade da rede e o tamanho dos mapas filhos.O algoritmo LBG (Linde-Buzo-Gray) ou K-means, um dos mais utilizado para desenvolver codebooks para quantiza??o vetorial, serviu justamente com o algoritmo de Kohonen na sua forma b?sica, isto ?, n?o hier?rquica, como refer?ncia para comparar o desempenho dos algoritmos aqui propostos. Uma an?lise de desempenho entre as duas estruturas hier?rquicas ? tamb?m realizada neste trabalho. A efici?ncia do processamento proposto ? verificada pela redu??o na complexidade computacional em rela??o aos algoritmos tradicionais, bem como, atrav?s das an?lises quantitativas das imagens reconstru?das em fun??o dos par?metros: (PSNR) rela??o sinal-ru?do de pico e (MSE) erro m?dio quadr?tico

Next-generation wireless communication systems will need to contend with many active mobile devices, each of which will require a very high data rate. To cope with this growing demand, network deployments are becoming denser, leading to higher interference between active users. Conventional architectures aim to mitigate this interference through careful design of signaling and scheduling protocols. Unfortunately, these methods become less effective as the device density increases. One promising option is to enable cellular basestations (i.e., cell towers) to jointly process their received signals for decoding users’ data packets as well as to jointly encode their data packets to the users. This joint processing architecture is often enabled by a cloud radio access network that links the basestations to a central processing unit via dedicated connections. One of the main contributions of this thesis is a novel end-to-end communications architecture for cloud radio access networks as well as a detailed comparison to prior approaches, both via theoretical bounds and numerical simulations. Recent work has that the following high-level approach has numerous advantages: each basestation quantizes its observed signal and sends it to the central processing unit for decoding, which in turn generates signals for the basestations to transmit, and sends them quantized versions. This thesis follows an integer-forcing approach that uses the fact that, if codewords are drawn from a linear codebook, then their integer-linear combinations are themselves codewords. Overall, this architecture requires integer-forcing channel coding from the users to the central processing unit and back, which handles interference between the users’ codewords, as well as integer-forcing source coding from the basestations to the central processing unit and back, which handles correlations between the basestations’ analog signals. Prior work on integer-forcing has proposed and analyzed channel coding strategies as well as a source coding strategy for the basestations to the central processing unit, and this thesis proposes a source coding strategy for the other direction. Iterative algorithms are developed to optimize the parameters of the proposed architecture, which involve real-valued beamforming and equalization matrices and integer-valued coefficient matrices in a quadratic objective. Beyond the cloud radio setting, it is argued that the integer-forcing approach is a promising framework for interference alignment between multiple transmitter-receiver pairs. In this scenario, the goal is to align the interfering data streams so that, from the perspective of each receiver, there seems to be only a signal receiver. Integer-forcing interference alignment accomplishes this objective by having each receiver recover two linear combinations that can then be solved for the desired signal and the sum of the interference. Finally, this thesis investigates the impact of channel coherence on the integer-forcing strategy via numerical simulations.

Made available in DSpace on 2014-12-17T14:56:22Z (GMT). No. of bitstreams: 1 DiegoMG.pdf: 1982662 bytes, checksum: e489eb42e914d358aaeb197489ceb5e4 (MD5) Previous issue date: 2006-01-05 / There has been an increasing tendency on the use of selective image compression, since several applications make use of digital images and the loss of information in certain regions is not allowed in some cases. However, there are applications in which these images are captured and stored automatically making it impossible to the user to select the regions of interest to be compressed in a lossless manner. A possible solution for this matter would be the automatic selection of these regions, a very difficult problem to solve in general cases. Nevertheless, it is possible to use intelligent techniques to detect these regions in specific cases. This work proposes a selective color image compression method in which regions of interest, previously chosen, are compressed in a lossless manner. This method uses the wavelet transform to decorrelate the pixels of the image, competitive neural network to make a vectorial quantization, mathematical morphology, and Huffman adaptive coding. There are two options for automatic detection in addition to the manual one: a method of texture segmentation, in which the highest frequency texture is selected to be the region of interest, and a new face detection method where the region of the face will be lossless compressed. The results show that both can be successfully used with the compression method, giving the map of the region of interest as an input / A compress?o seletiva de imagens tende a ser cada vez mais utilizada, visto que diversas aplica??es fazem uso de imagens digitais que em alguns casos n?o permitem perdas de informa??es em certas regi?es. Por?m, existem aplica??es nas quais essas imagens s?o capturadas e armazenadas automaticamente, impossibilitando a um usu?rio indicar as regi?es da imagem que devem ser comprimidas sem perdas. Uma solu??o para esse problema seria a detec??o autom?tica das regi?es de interesse, um problema muito dif?cil de ser resolvido em casos gerais. Em certos casos, no entanto, pode-se utilizar t?cnicas inteligentes para detectar essas regi?es. Esta disserta??o apresenta um compressor seletivo de imagens coloridas onde as regi?es de interesse, previamente fornecidas, s?o comprimidas totalmente sem perdas. Este m?todo faz uso da transformada wavelet para descorrelacionar os pixels da imagem, de uma rede neural competitiva para realizar uma quantiza??o vetorial, da morfologia matem?tica e do c?digo adaptativo de Huffman. Al?m da op??o da sele??o manual das regi?es de interesse, existem duas op??es de detec??o autom?tica: um m?todo de segmenta??o de texturas, onde a textura com maior freq??ncia ? selecionada para ser a regi?o de interesse, e um novo m?todo de detec??o de faces onde a regi?o da face ? comprimida sem perdas. Os resultados mostram que ambos os m?todos podem ser utilizados com o algoritmo de compress?o, fornecendo a este o mapa de regi?o de interesse