Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-12-02T16:31:53Z No. of bitstreams: 2 Tese - Divânia Dias da Silva França - 2016.pdf: 6690310 bytes, checksum: d6296e6724c1e38111bd12b6d97a4f46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-12-13T15:29:33Z (GMT) No. of bitstreams: 2 Tese - Divânia Dias da Silva França - 2016.pdf: 6690310 bytes, checksum: d6296e6724c1e38111bd12b6d97a4f46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-13T15:29:33Z (GMT). No. of bitstreams: 2 Tese - Divânia Dias da Silva França - 2016.pdf: 6690310 bytes, checksum: d6296e6724c1e38111bd12b6d97a4f46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-06-29 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Infection by human immunodeficiency virus (HIV) is a serious global public health problem. An estimated 78 million people have been infected. The burden of this infection is concentrated in high vulnerability groups, such as drug users. The objective of this study was to analyze the serological, epidemiological, and molecular profile of HIV infection in institutionalized crack users in Goiania, a large city in Central Brazil. This is an observational, analytical, cross-sectional study conducted among crack users in treatment in a mental health referral facilityin Midwestern Brazil. From August 2012 to April 2013, 600 crack users were recruited. All were interviewed and tested for HIV by enzyme-linked immunosorbent assay (ELISA). The samples that tested positive for anti-HIV1 were subjected to detection of HIV RNA by RT-PCR and genotyped by sequencing. Of the total enrolled participants: about half came from outside the city (50.3%), were predominantly male (84.5%), young (median: 30 years), had low education (8.4 years of school), were self-declared mixed race (61.5%), single (66.5%) and religious (74.3%). Nearly three-quarters were not formally employed, and 20.3% reported a history of life on the street in the last 180 days. Of the total, 2.8% (95% CI: 1.7 – 4.4%) were anti-HIV1 positive, ranging from 2.2% (95% CI 1.2 – 3.9) in men and 6.5% (95% CI 3.2 – 14.2) in women (p = 0.04). Logistic regression analysis revealed that history of sexual intercourse with a carrier of HIV (adjusted OR: 12.60; p = 0.001) and history of life on the street (adjusted OR: 4.43; p = 0.025) were predictors of HIV- 1. The variables: history of sexually transmitted infections (adjusted OR: 3.24; p = 0.057), not using a condom (adjusted OR: 2.84; p = 0.088) and consumption of more than 10 rocks/portions of crack daily (adjusted OR: 2.81; p = 0.085) were marginally associated with HIV infection. In 12 of 17 HIV-1 samples, subtype identification was possible with subtype B being detected in eight samples (66.7%), F1 and C in one sampleeach (8.3%), and recombinant BF in two samples (16.7%). These results highlight the need for effective strategies to prevent HIV infection in crack users, with an emphasis on health education, implementation of harm reduction measures and control of sexually transmitted diseases. / A infecção pelo vírus da imunodeficiência humana (HIV) é um grave problema de saúde pública mundial. Estima-se que 78 milhões de pessoas já se infectaram pelo HIV. A carga dessa infecção está concentrada em grupos com elevada vulnerabilidade, como usuários de drogas. O objetivo do presente estudo foi analisar o perfil soroepidemiológico e molecular da infecção pelo HIV em usuários de crack institucionalizados em Goiânia-GO. Trata-se de um estudo observacional, analítico, de corte transversal realizado com usuários de crack em tratamento em uma instituição de referência em saúde mental da Região Centro-Oeste do Brasil. No período de agosto de 2012 a abril de 2013, foram recrutados 600 usuários de crack. Todos foram entrevistados e testados para anti-HIV pelo ensaio imunoenzimático (ELISA). As amostras que apresentaram positividade para anti-HIV foram submetidas à detecção do RNA-HIV por RT-PCR e genotipadas por sequenciamento. Do total dos indivíduos recrutados, 50,3% eram procedentes de outros munícipios, predominantemente do sexo masculino (84,5%), jovens (mediana: 30 anos), de baixa escolaridade (média: 8,4 anos de estudo), se autodeclaram de cor parda (61,5%), solteiros (66,5%) e possuíam alguma religião (74,3%). Quase três quartos não desenvolviam suas atividades laborais no mercado formal de trabalho, e 20,3% relataram antecedentes de vida na rua nos últimos 180 dias. Do total, 2,8% (IC 95%: 1,7 – 4,4%) foram anti-HIV positivos, variando de 2,2% (IC 95%: 1,2 – 3,9) em homens e 6,5% (IC 95%: 3,2 – 14,2) em mulheres (p=0,04). Análise de regressão logística revelou que história de relação sexual com portador (a) do HIV (OR ajustado: 12,60; p= 0,001) e antecedente de vida na rua (OR ajustado: 4,43; p= 0,025) foram preditores da infecção pelo HIV. As variáveis: história de infecções sexualmente transmissíveis (OR ajustado: 3,24; p= 0,057), não adesão ao uso de preservativo (OR ajustado: 2,84; p= 0,088) e consumo de mais de 10 pedras/porções de crack diariamente (OR ajustado: 2,81; p= 0,085) foram marginalmente associadas à infecção pelo HIV. Em 12/17 amostras anti-HIV-1 foi possível a identificação subtípica, sendo detectados os subtipos B em oito amostras (66,7%), F1 e C em uma amostra cada (8,3%) e o recombinante BF em duas amostras (16,7%). Os resultados evidenciam a necessidade de estratégias efetivas de prevenção da infecção pelo HIV em usuários de crack institucionalizados, com ênfase em educação em saúde, implementação de medidas de redução de danos e controle de infecções de transmissão sexual.

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Elastic-plastic finite element analyses were performed to predict the crack opening level profiles in semi-elliptical surface cracks. A script was written to use the commercial finite element code ANSYS to predict opening levels in cracked geometries. The functionality of the scripts was verified by comparing predicted opening levels in two and three-dimensional center-cracked geometries to experimental results. In addition, a parameter study was performed in which various aspects of the modeling routine were modified. This included a mesh refinement study as well as a study into the effect of a strain hardening material. The main focus of the current research, however, is to compare finite element predicted opening levels with published opening levels determined experimentally. Due to the complexities and long run-times involved with these models, no attempt was made at growing the cracks from initial length to final length. Instead, discrete crack lengths at which experimental opening levels were published were instead used. Also, no attempt was made to predict the crack aspect ratio evolution. The finite element predicted opening levels were in all cases significantly lower than those reported experimentally, however, similar trends in both crack opening level profile along the crack front, and opening level variations with crack growth were shown.

For the characterization of crack advance in mechanical components and specimens under monotonic and fatigue loading, many engineering approaches use the assumption that the plastic deformation at the crack tip is isotropic. There are situations when this assumption is not correct, and the modeling efforts require additional correction factors that account for this simplification. The goal of this work is to study two cases where the plastic anisotropy at the crack tip is predominant and influences the magnitude crack-tip parameters, which in turn determine the amount of crack advance under applied loading. At the microstructural level, the small crack issue it is a long-standing problem in the fatigue community. Most of the small crack models consider that the plastic deformation at the crack tip is isotropic. The proposed approached for analyzing small crack growth is to perform finite element simulation of small cracks growing in a material that is assigned single crystal plastic properties. The nature of the plastic deformation of the material at the crack tip in the intra-granular regions could be accurately described and used for modeling small crack growth. By employing finite element analyses for stationary and growing cracks, the main characteristics of the plastic deformation at the crack tip, such as plastic zone sizes and shapes, crack-tip opening displacements, crack-tip opening stresses, are quantified and crack growth rates are determined. Ultimately, by using this crystal plasticity model calibrated for different microstructures, important time and financial resources for real experiments for the study of small cracks can be spared by employing finite element simulations. At macroscale, it is widely known that the manufacturing processes for aluminum alloys results in highly anisotropic microstructures, known as textures. The plastic behavior of these types of materials is far from isotropic and even the use of classical anisotropic yield criteria, such as that on Hill (Hill, 1950), is far from producing accurate results for describing the plastic deformation. Two of these anisotropic yield functions are implemented into finite element code ANSYS and stationary cracks are studied in a wide variety of textures. Significant variations of the plastic deformation at the crack due to the anisotropy are revealed.

Many components of existing civil infrastructure systems, such as road pavement, bridges, and buildings, are suffered from rapid aging, which require enormous nation's resources from federal and state agencies to inspect and maintain them. Crack is one of important material and structural defects, which must be inspected not only for good maintenance of civil infrastructure with a high quality of safety and serviceability, but also for the opportunity to provide early warning against failure. Conventional human visual inspection is still considered as the primary inspection method. However, it is well established that human visual inspection is subjective and often inaccurate. In order to improve current manual visual inspection for crack detection and evaluation of civil infrastructure, this study explores the application of computer vision techniques as a non-destructive evaluation and testing (NDE&T) method for automated crack detection and quantification for different civil infrastructures. In this study, computer vision-based algorithms were developed and evaluated to deal with different situations of field inspection that inspectors could face with in crack detection and quantification. The depth, the distance between camera and object, is a necessary extrinsic parameter that has to be measured to quantify crack size since other parameters, such as focal length, resolution, and camera sensor size are intrinsic, which are usually known by camera manufacturers. Thus, computer vision techniques were evaluated with different crack inspection applications with constant and variable depths. For the fixed-depth applications, computer vision techniques were applied to two field studies, including 1) automated crack detection and quantification for road pavement using the Laser Road Imaging System (LRIS), and 2) automated crack detection on bridge cables surfaces, using a cable inspection robot. For the various-depth applications, two field studies were conducted, including 3) automated crack recognition and width measurement of concrete bridges' cracks using a high-magnification telescopic lens, and 4) automated crack quantification and depth estimation using wearable glasses with stereovision cameras. From the realistic field applications of computer vision techniques, a novel self-adaptive image-processing algorithm was developed using a series of morphological transformations to connect fragmented crack pixels in digital images. The crack-defragmentation algorithm was evaluated with road pavement images. The results showed that the accuracy of automated crack detection, associated with artificial neural network classifier, was significantly improved by reducing both false positive and false negative. Using up to six crack features, including area, length, orientation, texture, intensity, and wheel-path location, crack detection accuracy was evaluated to find the optimal sets of crack features. Lab and field test results of different inspection applications show that proposed compute vision-based crack detection and quantification algorithms can detect and quantify cracks from different structures' surface and depth. Some guidelines of applying computer vision techniques are also suggested for each crack inspection application.

A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens was performed using the finite element code ABAQUS. A three-dimensional crack propagation procedure based on the crack tip opening angle (CTOA) was developed using Python. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the non-reinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement. The amount of load transfer is linked to strains experienced by the reinforcement ahead of the crack tip. / Master of Science

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