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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Comparação entre métodos de fixação interna utilizadas no tratamento de fraturas do ângulo mandibular = estudo mecânico / Comparison of internal fixation methods in the management of mandibular angle fractures : mechanical study

Lyrio, Mariana Camilo Negreiros, 1980- 06 October 2011 (has links)
Orientadores: Valfrido Antonio Pereira Filho, Marcio de Moraes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T20:34:21Z (GMT). No. of bitstreams: 1 Lyrio_MarianaCamiloNegreiros_D.pdf: 27352279 bytes, checksum: c9fcc8fa65410e2e71a94c3f054de2c6 (MD5) Previous issue date: 2011 / Resumo: Apesar dos diversos tipos de fixação interna existentes ainda não há um consenso quanto ao método de imobilização das fraturas do ângulo mandibular. Além disso, são poucos os estudos sobre a utilização de placas grade ultimamente lançadas no mercado. O presente estudo visou avaliar comparativamente a resistência entre três tipos de fixação interna em réplicas de hemimandíbulas de poliuretano seccionadas na região de ângulo mandibular, simulando uma fratura linear. As formas de fixação incluíram a utilização de placas em forma de grade com e sem barra intermediária e o método descrito por Champy (1978). O objetivo foi definir por meio de análise mecânica a técnica que permitiu maior resistência na fixação deste tipo de fratura. Os testes de carregamento linear vertical foram realizados em amostras de cada grupo estudado (n = 10) utilizando uma unidade de testes mecânicos para registro da carga atingida, nos momentos que o deslocamento vertical alcançou 3 mm e 5 mm. Médias e desvio padrão foram avaliados aplicando-se a Análise de Variância e o teste de Duncan em nível de significância de 5%. Concluiu-se que a técnica de fixação interna para as fraturas de ângulo mandibular descrita por Champy (1976) foi a mais resistente e, que a inclusão de barra vertical intermediária nas placas grade não ofereceu aumento da resistência quando comparadas às placas grade sem barra / Abstract: Although there are several methods of stable fixation, there is no consensus about the treatment of mandibular angle fractures, Also, there are few studies about grid plates recently commercially available. This study compares the resistance of three fixation methods in polyurethane hemimandible replicas. Those were osteotomized at the angle region to simulate a linear fracture. Fixation methods were four-hole 2.0mm grid plates with and without a vertical intermediate bar and 2.0mm four-hole straight plate. The objective was to determine, through mechanical analysis, the fixation method that results in greater resistance to displacement. The hemimandibles were submitted to vertical linear loading in a mechanical test unit for registration of load after displacement of 3 and 5mm. Means and standard deviation were determined. Variance analysis and Ducan's test were applied considering a significance level of 5%. Results showed that the 2.0 four-hole plates, positioned according to the Champy technique, provide greater stability than the grid plates. When a vertical intermediate bar was added to the grid plates, resistance of the system was not increased / Doutorado / Cirurgia e Traumatologia Buco-Maxilo-Faciais / Doutor em Clínica Odontológica
222

Uso da Bota de Unna comparado à bandagem elástica em úlceras venosas: estudo clínico

Abreu, Alcione Matos de January 2012 (has links)
Submitted by Fabiana Gonçalves Pinto (benf@ndc.uff.br) on 2015-11-26T18:23:43Z No. of bitstreams: 1 Alcione Matos de Abreu.pdf: 2227189 bytes, checksum: f73eb32bdd92709cccf5f1c0b4627d4d (MD5) / Made available in DSpace on 2015-11-26T18:23:43Z (GMT). No. of bitstreams: 1 Alcione Matos de Abreu.pdf: 2227189 bytes, checksum: f73eb32bdd92709cccf5f1c0b4627d4d (MD5) Previous issue date: 2012 / Universidade Federal Fluminense. Escola de Enfermagem Aurora de Afonso Costa / Este estudo teve os objetivos de avaliar os resultados clínicos e evolutivos do processo de reparo teci-dual em pacientes com úlcera venosa em uso da terapia compressiva inelástica (Bota de Unna) em comparação ao uso da terapia compressiva elástica (atadura elástica); e, analisar se existe variação significativa na área da úlcera ao longo de 13 semanas de tratamento nos dois grupos. Metodologia: Trata-se de um estudo clínico experimental randomizado e controlado, aberto, prospectivo, com abor-dagem quantitativa, realizado em um hospital universitário. A amostra foi de 18 pacientes, acompa-nhados por 13 semanas. Para alocação aleatória foi realizada uma lista através do software Biostat 5.0 que realizou o sorteio dos participantes em um dos grupos, onde metade destes utilizaram como trata-mento para as úlceras venosas a Bota de Unna, e a outra metade a atadura elástica. Todos os voluntá-rios atenderam aos critérios de inclusão. Este estudo foi aprovado pelo Comitê de Ética em Pesquisa da Faculdade de Medicina, sob o protocolo nº 327/2010 e CAAE:0252.0.258-000-10, os termos de consentimento e fotografia encontram-se de acordo com as Resoluções 196/96. A coleta de dados foi realizada durante seis meses, pela enfermeira pesquisadora e por uma bolsista de iniciação científica. Os dados foram analisados no SPSS 14.0 Windows, através de estatística descritiva e inferencial, e apresentados na forma de tabelas, quadros e gráficos. Entre os pesquisados, pôde-se identificar que (61,1%) eram homens e adultos, moradores de Niterói /RJ (66,6%) e com baixo grau de escolaridade (55,5%). Em relação às características clínicas das úlceras, encontrou-se que no grupo B, úlceras mais exsudativas, com maior tempo de evolução e maiores áreas. Já o Grupo A apresentou o maior numero de úlceras com presença no leito com tecido de hipergranulação e ou desvitalizado e destacou-se como a terapia compressiva mais confortável. O uso da Bota de Unna macerou as bordas das úlceras e a Gaze Petrolatum® levou a formação de crostas perilesional. Em relação a redução da área das úlceras venosas, pelo teste de ANOVA de Friedman, observou-se que existe queda significativa, ao nível de 5%, na área da úlcera apenas no grupo B (p < 0,0001) ao longo de todo o tratamento, mas pode-se dizer, que existe uma tendência do grupo A apresentar queda na área da lesão (p = 0,06), após a 5ª consulta. Conclui-se que a Bota de Unna apresentou melhor resultado em úlceras venosas com áreas superiores a 10 cm² e o uso da Gaze Petrolatum® com a atadura elástica em úlceras venosas inferiores a 10 cm². / This study aimed to evaluate clinical and evolutionist results of the process of tissues repairing in pa-tients with venous ulcer using the compressive inelastic (Unna Boot) comparing the usage of compres-sive elastic therapy (elastic bandage) and analyzing if there is a meaningful variation in the ulcer area with 13 weeks of treatment in both groups. Methodology: Concerning in a experimental, randomized and controlled, opened, prospective study with quantitative approach in a College Hospital. A sample of 18 patients was monitoring for 13 weeks. It was achieved a list of two groups in randomized draw by Biostat 5.0 software where half of participants used as therapy Unna Boot in venous ulcer and the other half of them used the elastic bandage one. All volunteers followed the inclusion criteria. This study was approved by The Committee of Ethics in research of Medical College; under the protocol number no 327/2010 and CAAE: 0252.0.258-000-10, terms of authorization and photography are in agreement to the resolutions 196/96. The data collection was done for six months by researcher nurse and a scholarship student of scientific study. Such data were analyzed in SAS 6.11, through descrip-tive and inferential statistic and performed in tables, squares and graphs. Among participants could identify that (61%) were adult male; inhabitants from Niteroi/RJ (66,6%) with a low degree of educa-tion (55,5%). Regarding to the ulcer clinical characteristics in Unna Boot group was found ulcers with more exsudation, with longer evolution time and larger areas. In elastic bandage group, a great number of ulcers with hyper-granulation and or desvitalization tissue on the bed was remarkable as the most comfortable compressive therapy. The usage of Unna Boot softened the ulcer borders and in the Petro-latum® Gaze took as a result a formation of a scab around the lesion. In relation to the reduction of venous ulcer area due to the ANOVA Friedman Test, analyzed that there is a meaningful decrease to the level of 5%, in the ulcer area in group B (p<0,0001) along of all the treatment, but there is a ten-dency of group A in performing a reduction in the affected area after the 5th consultation. Concluding that the Unna Boot performed better/satisfactory results in venous ulcer with area superior to 3.93 in². and the usage of Petrolatum® Gaze with elastic bandage in venous ulcer was inferior to 3.93 in².
223

Effect of Mineral and Chemical Admixtures on Durability of Cementitious Systems

Tran, Victor 05 November 2015 (has links)
Mineral and chemical admixtures are used today in almost all concrete mixtures to improve concrete fresh and hardened properties, and to enhance concrete durability. In this study, four mineral and four chemical admixtures were investigated: namely, metakaolin (MK), silica fume (SF), Class F fly ash (FA), blast-furnace slag (BFS), two high-range water reducers (SP), water reducer/retarder (WRD), and air-entrainer (AEA). The objective of this study is to assess the effects of commonly used mineral and chemical admixtures on the durability of the cementitious system. Two durability issues were addressed in this study: the potential of the cementitious system to generate heat, and sulfate durability. The properties studied here included heat of hydration (HOH) measurements using isothermal calorimetry, setting properties, compressive strength, and expansion on exposure to a sodium sulfate solution. X-ray diffraction was used to characterize the as-received materials and explain failure trends. The findings of this study indicate that silica fume inclusion sustains superior durability in comparison to the other mineral admixtures considered here. Replacement levels as low as 10% outperformed the other admixtures studied. Fly ash showed improvement in the workability of the mixes, but had the lowest compressive strength results and might pose challenges when the rate of strength gain is critical. However, Class F fly ash mixtures showed better performance than unblended mixtures when exposed to a sulfate source. Metakaolin mixes showed higher heat evolution among all the mixtures studied here. This can potentially lead to durability concerns, especially when temperature rise is a design concern. Blast-furnace slag also improved the workability of the mixes and the later compressive strength, but had mixed performances when examined for sulfate durability.
224

Evaluación de pavimentos rígidos mediante la determinación de correlaciones entre el módulo de rotura a la flexión y la resistencia a la compresión para el Centro Poblado San Cristóbal de Chupán – Huaraz

Robles Sáenz, Randolp Julián, Sánchez Medina, Juan Carlos January 2015 (has links)
La resistencia a flexión y la resistencia a la compresión representan parámetros fundamentales en el correcto desarrollo de los pavimentos rígidos, porque definen la calidad del concreto, principal componente de los pavimentos rígidos, después de cumplir satisfactoriamente su ciclo de fraguado y curado. En nuestro enfoque cuantitativo, el problema principal radica en intentar efectuar ensayos de rotura a la flexión en zonas alejadas, como en el centro poblado San Cristóbal de Chupán, reconociendo que sólo es posible realizarlo en pocos laboratorios a nivel nacional. Por esta razón se determinó, en base a ensayos realizados en laboratorio, un factor de correlación que vincula el Módulo de Rotura a la flexión y la Resistencia a la Compresión, siendo el resultado experimental el factor (k) expresado por la ecuación Mr = (k)*√f’c, que identifica rápidamente resultados del Módulo de Rotura a la flexión, aplicable a proyectos de condiciones similares, ante las altas exigencias del control de calidad en los proyectos de construcción. The flexural strength and the compressive strength are fundamental parameters in the correct development of rigid pavements, because they define the quality of concrete, principal component of rigid pavements, after performing successfully their setting and curing cycle. In our quantitative approach, the principal problem has roots in realizing flexural strength tests in remote rural areas such as San Cristobal de Chupán populated, recognizing could only do it in a few laboratories nationwide. Therefore written, it is determined a correlation factor, based on laboratory tests, what can relating Flexural strength and compressive strength. The experimental result express a factor (k), what is on the equation Mr = (k)*√f'c, which quickly identifies results of Flexural Strength, applicable to projects of similar conditions, to the demands of quality control in construction projects.
225

Greedy algorithms for multi-channel sparse recovery

Determe, Jean-François 16 January 2018 (has links)
During the last decade, research has shown compressive sensing (CS) to be a promising theoretical framework for reconstructing high-dimensional sparse signals. Leveraging a sparsity hypothesis, algorithms based on CS reconstruct signals on the basis of a limited set of (often random) measurements. Such algorithms require fewer measurements than conventional techniques to fully reconstruct a sparse signal, thereby saving time and hardware resources. This thesis addresses several challenges. The first is to theoretically understand how some parameters—such as noise variance—affect the performance of simultaneous orthogonal matching pursuit (SOMP), a greedy support recovery algorithm tailored to multiple measurement vector signal models. Chapters 4 and 5 detail novel improvements in understanding the performance of SOMP. Chapter 4 presents analyses of SOMP for noiseless measurements; using those analyses, Chapter 5 extensively studies the performance of SOMP in the noisy case. A second challenge consists in optimally weighting the impact of each measurement vector on the decisions of SOMP. If measurement vectors feature unequal signal-to-noise ratios, properly weighting their impact improves the performance of SOMP. Chapter 6 introduces a novel weighting strategy from which SOMP benefits. The chapter describes the novel weighting strategy, derives theoretically optimal weights for it, and presents both theoretical and numerical evidence that the strategy improves the performance of SOMP. Finally, Chapter 7 deals with the tendency for support recovery algorithms to pick support indices solely for mapping a particular noise realization. To ensure that such algorithms pick all the correct support indices, researchers often make the algorithms pick more support indices than the number strictly required. Chapter 7 presents a support reduction technique, that is, a technique removing from a support the supernumerary indices solely mapping noise. The advantage of the technique, which relies on cross-validation, is that it is universal, in that it makes no assumption regarding the support recovery algorithm generating the support. Theoretical results demonstrate that the technique is reliable. Furthermore, numerical evidence proves that the proposed technique performs similarly to orthogonal matching pursuit with cross-validation (OMP-CV), a state-of-the-art algorithm for support reduction. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
226

Low power real-time data acquisition using compressive sensing

Powers, Linda S., Zhang, Yiming, Chen, Kemeng, Pan, Huiqing, Wu, Wo-Tak, Hall, Peter W., Fairbanks, Jerrie V., Nasibulin, Radik, Roveda, Janet M. 18 May 2017 (has links)
New possibilit ies exist for the development of novel hardware/software platforms havin g fast data acquisition capability with low power requirements. One application is a high speed Adaptive Design for Information (ADI) system that combines the advantages of feature-based data compression, low power nanometer CMOS technology, and stream computing [1]. We have developed a compressive sensing (CS) algorithm which linearly reduces the data at the analog front end, an approach which uses analog designs and computations instead of smaller feature size transistors for higher speed and lower power. A level-crossing sampling approach replaces Nyquist sampling. With an in-memory design, the new compressive sensing based instrumentation performs digitization only when there is enough variation in the input and when the random selection matrix chooses this input.
227

The influence of moulding moisture content on the engineering properties of aggregate-lime-natural pozzolan mixes

Olekambainei, Arip-Kituyan Emmanuel 09 June 2005 (has links)
The current trends in the road transport sector show a growth in axle loads as well as vehicle numbers on all types of roads in highly industrialised countries as well as in developing countries. This increase in axle loads and numbers has forced road agencies to amend their design standards adopting designs that provide roads with higher load bearing capacity. However, the rapid depletion of natural road construction gravel, as well as strict environmental conservation laws have resulted in many agencies in-charge of road construction and maintenance to resort to use of alternative materials that will be economically feasible and environmental friendly. The use of natural pozzolans for stabilising pavement layers fulfils this requirement. This research study was performed with the aim of evaluating the engineering properties of aggregate-lime-natural pozzolan (ALP) mixtures at varying compaction degrees of saturation and to compare them with conventional cement-stabilized aggregates. Two types of pozzolans found in Tanzania were used. The laboratory investigation was carried out in two parts, namely a pilot investigation where the strength behaviour with time, shrinkage and CBR were determined at three degrees of saturation for a washed river sand specimen followed by the main investigation using two different types of sands at four varying degrees of saturation. The study showed that the compaction degree of saturation for ALP mixes plays an important role in their tensile and compressive strengths development regardless of their optimum moisture contents. The ratio between tensile and compressive strengths for ALP mixes was also found to closely obey the relation given by Fulton (2001) for concrete. The ALP mixes were also observed to develop their strength similar to cement mixes with the formation of tobermorite crystals with the additional of water and appropriate activator. Both pozzolan mixes developed significant tensile and compressive strength after 28 days of curing similar to cement mixes. High CBR values for the two ALP mixes were obtained in mixes moulded at degrees of saturation lower than that corresponding to their optimum. Similarly, the shrinkage of the mixes was found to decrease with a decrease in the degrees of saturation. The CBR and shrinkage of the ALP mixes were found to show similar trend to that of the control cement mixes. The ALP mixes showed no significant strength loss with an increase in the fines content in unwashed sand mix in comparison with that of washed sand mixes. No significant strength loss was observed in the ALP mixes as in the control cement mixes at all moulding degrees of saturation. Finally the study concluded that the ALP mixes could be used in stabilization of pavement layers. However, care must be taken in deciding the compaction degrees of saturation as the specifications used in conventional cement stabilization does not necessarily yield desirable strength development in ALP mixes. / Dissertation (MEng (Transportation))--University of Pretoria, 2006. / Civil Engineering / unrestricted
228

Existencia e unicidade de solução fraca global das equações de Navier-Stokes em uma dimensão para fluidos isentropicos compressiveis com a viscosidade dependente da densidade / On global weak solutions to ID compressible isentropic Navier-Stokes equações with density-dependent viscosity

Teixeira, Edson José, 1984- 14 August 2018 (has links)
Orientador: Marcelo Martins dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatística e Computação Científica / Made available in DSpace on 2018-08-14T14:51:49Z (GMT). No. of bitstreams: 1 Teixeira_EdsonJose_M.pdf: 638751 bytes, checksum: 1d26a9bbc1ee3ba6c4ee45e29c14c45e (MD5) Previous issue date: 2009 / Resumo: Este trabalho consiste de uma exposição detalhada do resultado provado no artigo "Global weak solutions to 1D compressible isentropic Navier-Stokes equations with density-dependent viscosity" de S. Jiang, Z. P. Xin e P. Zhang (Methods Appl. Anal. - 2005), sobre a existência e unicidade de solução fraca para o sistema de Navier-Stokes unidimensional de um fluido isentrópico compressível com viscosidade dependente da densidade e com fronteira livre em coordenadas lagrangianas, ?t +?2ux = 0 0 < x < 1, t > 0 ut + (P(?))x = (?µ (?)ux)x 0 < x < 1, t > 0 onde ?, u; P(?) e µ(?) são a densidade, velocidade, pressão e viscosidade do fluido, e exigiremos que este fluido satisfaça a condição de fronteira (-P(?) + (?µ(?)ux)= 0. Trataremos do caso particular onde consideramos P(?) = A ?? e µ( ?) = B?a; onde A, B > 0,? > 1 e 0 < a < 1 são constantes. Acrescentaremos uma condicão inicial (?0,u0). / Abstract: The present work makes a well-detailed exposition about the main results given in the paper "Global weak solutions to 1D compressible isentropic Navier-Stokes equations with densitydependent viscosity" by S. Jiang, Z. P. Xin and P. Zhang (Methods Appl. Anal. - 2005). The problem in this paper has a free boundary but in lagrangian coordinates the equations are the following, ?t +?2ux = 0 0 < x < 1, t > 0 ut + (P(?))x = (?µ (?)ux)x 0 < x < 1, t > 0 and the boundary becomes the fixed points x = 0 and x = 1; Here ?, u; P(?) and µ(?) are, respectively, the density, velocity, pressure and the viscosity of the fluid. The boundary condition, at x = 0 and x = 1, is given by (-P(?) + (?µ(?)ux)= 0. Although the pressure and viscosity may have more general forms, to be more specific, the authors consider only the special case P(?) = A ?? e µ( ?) = B?a, with A; B > 0,? > 1 and 0 <a< 1 being constants. An initial condition (?0,u0) is also given at time t = 0. / Mestrado / Analise, Equações Diferenciais Parciais / Mestre em Matemática
229

A Relationship Between the Strengths of Type N Cubic Mortar Specimens and In-Situ Mortar

Reynolds, Michael Scott 01 May 2019 (has links)
The compressive strength of mortar is typically determined using the American Societyfor Testing and Materials (ASTM) standard method using 2 inch cubes which are compressed tillfailure. There is however a disparity between the compressive strengths of mortar cubes, and insitumortar. This disparity is a result of the differences in thickness, aspect ratio, curingconditions, water content, and confinement between mortar cubes and mortar joints. While thesedifferences lead to mortar joints being stronger than mortar cubes, a relationship between theirstrengths is desired.Two less-common mortar strength tests were used to determine more accurately thecompressive strength of in-situ mortar. The results of both tests were compared to the results ofASTM standard compressive testing with mortars of the same water content. The first was theDouble Punch test which involves the use of two metal punches that compress either side of athin mortar sample till failure. The Double Punch test is more difficult to perform than theASTM standard compression test, but was useful because it simulates the confinement that insitumortar will experience. The Double Punch test was also used with mortar specimens ofvarying thickness to determine a relationship between specimen thickness and compressivestrength. The second test used was the Helix Pullout test. This test is performed by insertingmetal helical screws into a mortar joint, and pulling from the joint while restricting rotation. Themaximum load used to extract the Helix is recorded as the Pullout Load, and is used to find thecompressive strength by use of a calibration curve. This test was used on a masonry wall paneland mortar cubes were also made with the same mortar for compressive testing.The tested mortar exhibited decreased compressive strength with increased water content.The mortar also decreased in strength with increasing specimen thickness. Mortar joints wereshown to be significantly stronger than mortar cubes based on factors of specimen thickness andconfinement by an average factor of at least 2.40. Although results are affected by punchdiameter, the Double Punch test was shown to be a consistent and reliable means of estimatingmortar compressive strength. The Helix Pullout test exhibited wide variation, and wasdetermined to be primarily useful for qualitative comparison as opposed to quantitativedetermination of strength.
230

Building Constraints, Geometric Invariants and Interpretability in Deep Learning: Applications in Computational Imaging and Vision

January 2019 (has links)
abstract: Over the last decade, deep neural networks also known as deep learning, combined with large databases and specialized hardware for computation, have made major strides in important areas such as computer vision, computational imaging and natural language processing. However, such frameworks currently suffer from some drawbacks. For example, it is generally not clear how the architectures are to be designed for different applications, or how the neural networks behave under different input perturbations and it is not easy to make the internal representations and parameters more interpretable. In this dissertation, I propose building constraints into feature maps, parameters and and design of algorithms involving neural networks for applications in low-level vision problems such as compressive imaging and multi-spectral image fusion, and high-level inference problems including activity and face recognition. Depending on the application, such constraints can be used to design architectures which are invariant/robust to certain nuisance factors, more efficient and, in some cases, more interpretable. Through extensive experiments on real-world datasets, I demonstrate these advantages of the proposed methods over conventional frameworks. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

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