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[en] EVALUATION OF THE MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF THE GIRTH WELDING OF AN API 5L X80 STEEL TUBE BY SEMI-AUTOMATIC WELDING PROCESSES WITH GAS SHIELDING / [pt] AVALIAÇÃO DA MICROESTRUTURA E PROPRIEDADES MECÂNICAS DA SOLDAGEM CIRCUNFERENCIAL DO AÇO API 5L X80 POR PROCESSOS DE SOLDAGEM SEMI-AUTOMÁTICOS COM PROTEÇÃO GASOSARICHARD ZACARIAS SANZ DURAND 04 December 2007 (has links)
[pt] O presente trabalho avalia a evolução da microestrutura e
as propriedades
mecânicas devido à influência do aporte de calor exercido
por um procedimento
de soldagem que utilizou sequencialmente dois processos de
soldagem sobre
um tubo de aço API 5L X80, fabricado pelo processo UOE, de
um aço produzido
por laminação controlada sem resfriamento acelerado. A
soldagem foi realizada
em um tubo de 20 de diâmetro nominal e 3/4 de espessura,
fixado na posição
horizontal simulando condições de campo, usando o processo
MAG de curtocircuito
de corrente controlada com gás de proteção CO2 (100%) para
o passe
de raiz e o processo por Arame Tubular com proteção gasosa
Ar - CO2 (80% -
20%) para os demais passes. As propriedades mecânicas
foram avaliadas
segundo os ensaios mecânicos exigidos na norma API 1104,
além dos ensaios
de microdureza Vickers e de impacto Charpy V. As mudanças
microestruturais
na Zona Afetada Termicamente e Material de Solda foram
avaliadas por
microscopia eletrônica de varredura (MEV) e microscopia
óptica. A avaliação
mecânica segundo a norma API 1104 foi reprovada, onde os
resultados dos
ensaios de tração e Nick-Break foram aceitos e o ensaio de
dobramento lateral
um corpo-de-prova apresentou uma trinca superior ao
comprimento máximo
aceitável. Os resultados da microdureza foram aceitáveis e
o resultado do
impacto Charpy V, segundo a norma DNV-OS-F101, para a
temperatura de 0 °C
foi insatisfatório na região do metal de solda dos passes
de acabamento. A
região da ZTA apresentou maior energia de impacto quando
comparado com o
material de base à temperatura de 0 °C, embora com
presença do
microconstituinte A-M. / [en] The present work evaluates the changes in the
microstructural and
mechanical properties of an API 5L X80 steel tube due to
the influence of heat
input exerted during a welding procedure that used two
sequential welding
processes. The tubes were manufactured using the UOE
process, from steel
that was produced by controlled rolling without
accelerated cooling. The welding
was carried out on a 3/4 thick and 20 nominal diameter
pipe, while it was held in
a horizontal position in order to simulate field
conditions, using a controlled short
circuit GMAW process with CO2 (100%) gas shielding for the
root pass and a flux
cored arc welding process with Ar-CO2 (80% - 20%) gas
shielding for the other
passes. The evaluation of the mechanical properties was
done by means of
mechanical tests according to the API 1104 standard, in
addition to the Vickers
microhardness and Charpy V-notch tests. The changes in the
microstructure of
the Heat Affected Zone (HAZ) and the welded metal were
evaluated by means of
scanning electronic microscopy (SEM) and optical
microscopy. The mechanical
evaluation was unsatisfactory according to the API 1104
standard, while the
tensile and Nick-Break test results were acceptable. The
side bend test showed
a crack in a specimen that exceeded the maximum acceptable
value. The
Vickers microhardness results were acceptable and the
Charpy V-notch result,
according to the DNV-OS-F101 standard, at a temperature of
0 °C, was
unsatisfactory in the weld metal region of the over cap.
The HAZ region showed
greater energy of impact absorption compared to the base
metal, at a
temperature of 0 °C, even with existence of the
microconstituent M-A.
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Exploring the Effects of Crosslinking on the Intervertebral DiscKirking, Bryan 14 March 2013 (has links)
Crosslinking soft tissue has become more common in tissue engineering applications, and recent studies have demonstrated that soft tissue mechanical behavior can be directly altered through crosslinking, but increased understanding of how crosslinking affects intervertebral disc mechanical behavior is needed. In vitro testing of bovine disc and motion segments was used to characterize several important aspects of disc behavior in response to crosslinking after both soaking and injection treatment.
The first study was a comparison of different crosslinkers to determine the effect on tensile properties of disc tissue. Circumferential specimens were taken from bovine annulus and then soak treated with an optimized crosslinking formulation or sham solution. A non-contacting laser micrometer was used to measure cross sectional area, after which tension testing until failure was performed to determine yield strain, yield stress, ultimate stress, peak modulus, and resilience. The crosslinkers were observed to produce different changes in the properties, with the measured properties generally increasing.
The second study used bilateral annular injections to simulate a clinically relevant delivery method. The dose response of the motion segment’s neutral zone stability metrics against injection concentration was mapped. Concentrations of 20 mM and less had no significant effects on the stability metrics. 40mM demonstrated a change in neutral zone stiffness, while at least 80mM was required to significantly affect neutral zone length. Thus, meaningful changes in joint neutral zone stability were demonstrated using clinically relevant injection and chemical formulations.
The third study used combinations of biochemical and accelerated mechanical cyclic loading to degrade gelatin and annulus fibrosus specimens with and without genipin treatment. Genipin crosslinking attenuated changes during cyclic loading to specimen geometry and compliance relative to control samples. Full recovery of genipin treated samples appeared to be hampered, at least partially from continued crosslinking during the accelerated testing.
The fourth study tested the effect of genipin crosslinking to resist interlamellar shearing of the annulus lamella. Using a recently reported test method that shears adjacent lamella, crosslinked specimens were noted to have significantly higher yield force, peak force, and resilience compared to sham treated controls, supporting the hypothesis that crosslinking would increase the load bearing ability of the interface.
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Effect of Geometric Imperfections (Wrinkles) on the Circumferential Strength of a Composite Polymer Liner for Pressure PipesAmpiah, Nancy 09 October 2008 (has links)
The relining of deteriorated gravity flow and pressure pipes with polymeric liners is now popular practice. In the water industry, health concerns and challenges associated with re-opening water services in a lined small diameter pipe have limited the use of liners. Sanexen Environmental Services Inc. in Montreal, Canada, manufactures a cured-in-place liner system which can restore water service connections after lining from within the pipe, using a remote controlled robot.
The installation of the liner within cast iron water pipes can result in the formation of geometric imperfections (wrinkles) as the external diameter of the liner often exceeds the internal diameter of the host pipe. Previous studies have suggested that the wrinkles have a detrimental effect on the structural performance of the liner. In this study, experimental and analytical investigations were conducted to evaluate further the effect of the wrinkles on the circumferential (hoop) strength of the liner.
The experimental investigation involved testing 33-25 mm wide ring samples of the liner with and without wrinkles, using the split-disk test method which is defined by ASTM Standard D2290. The laboratory tests were conducted to examine the effects on the response of the liner of loading rate, cyclic loading, and presence of different wrinkle configurations. A series of two-tailed Mann-Whitney statistical tests were conducted on the obtained test data. The analytical investigation examined the behavior of two of the three types of wrinkles observed in the liner using finite element models. The results from the models were evaluated using the experimental results.
This study confirmed that the wrinkles were a source of weakness in the liner as failure was initiated at the wrinkle in all the test samples. It also showed that their presence may or may not result in a reduction in the ultimate hoop tensile capacity of the liner depending on wrinkle pattern. The loading rate had no significant effect on the first cracking load of the resin within the wrinkle. However, lower ultimate hoop tensile capacities were observed at very slow loading rates. Under the 50-year cyclic loading, the resin within the wrinkle was susceptible to cracking while the jackets of the wrinkle remained intact. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-09-16 22:38:10.234
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[en] CIRCUMFERENTIAL WELDING OF API 5L X80 PIPE USING MANUAL AND SEMI-AUTOMATIC PROCESS / [pt] SOLDAGEM CIRCUNFERENCIAL DE TUBO API 5L X80 EMPREGANDO PROCESSOS MANUAL / SEMI-AUTOMÁTICOPERCY MARCO ANTONIO SAAVEDRA PINTO 30 October 2006 (has links)
[pt] O presente estudo faz parte de um projeto relacionado ao
estudo de
aplicação de tubos de aço API 5L Grau X80 fabricados no
Brasil e destinados
para a montagem de tubulações para o transporte de gás.
Objetiva-se avaliar os
parâmetros de soldagem empregados na execução da soldagem
circunferencial
combinando os processos de eletrodo revestido, para a
execução do passe de raiz
e passe quente, e arame tubular autoprotegido para a
execução dos passes de
enchimento e acabamento. Os resultados obtidos indicam que
embora o material
utilizado, tanto metal de solda como metal de base estejam
atendendo aos
requisitos básicos de tenacidade e resistência, em acordo
com as normas, a
qualificação do procedimento é dependente do desempenho
dos soldadores.
Existe portanto, a necessidade de habilitação técnica mais
ampla quanto a
formação de profissionais nesta área, excedendo assim o
escopo do presente
estudo cujo objetivo foi estudar e caracterizar a solda
circunferencial. As
propriedades mecânicas foram avaliadas mediante ensaios de
dureza, tração,
dobramento, ensaios nick-break e tenacidade mediante
ensaios de impacto
Charpy. A caracterização da junta soldada foi realizada,
utilizando-se
microscopia ótica e microscopia eletrônica de varredura.
Embora o
procedimento empregado não tenha sido qualificado pela
norma API 1104, em
função da execução do procedimento, os valores de
resistência mecânica obtidos
foram aceitáveis e a caracterização microestrutural e
mecânica da junta
comprova a não ocorrência de microestruturas frágeis, seja
no metal de solda ou
na ZTA. / [en] The current work is part of a larger project to study the
application of API
5L X80 steel tubes, produced in Brazil, in gas pipeline
fabrication. The objective
of this work is to evaluate the effects of the process
parameters used when
performing a circumferential welding technique which
combines the utilization
of coated electrodes for the root and hot passes, while
exploiting self-shielded
flux cored arc welding for the filling and finishing
passes. The results obtained
indicate that, though the material studied, both filler
metal and the base alloy,
meet the basic toughness and strength specifications of
the relevant standards,
the final overall quality of the joint is very dependent
on the skill of the welders.
Although there is a necessity to guarantee an adequate
level of training for these
professionals for such tasks, that would be beyond the
scope of then present
work, as it aims to emphasize the characterization of the
circumferential weld
itself. The mechanical properties were evaluated using
hardness measurements,
bend testing, nick-break tests and toughness was evaluated
by Charpy notchimpact
tests. The metallographic characterization of the girth
weld joint was
undertaken by means of optical and scanning electron
microscopy. Though the
specific methodology applied has not been qualified by the
API 1104 Standard,
as such, the strength values obtained were of acceptable
levels and an analysis of
the joint`s microstructure and overall mechanical
properties confirm that no
typical fragile structures or phases were present either
in the weld metal or the
heat affected zone.
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Circumferential Three-Dimensional Profiling with Specular Micro-Texture Photometry for Dark ObjectsSong, Mengyu 26 June 2020 (has links)
This dissertation proposes a novel approach to achieve circumferential three-dimensional (3D) profiling for dark objects by investigating specular micro-texture photometry. A small patch of a target surface in micro-texture level yields different appearance under different illumination. This photometric property can be used to reconstruct the target surface with pixel-level resolution. However, due to the nature of some material, the surface of whom has stronger specular components than diffuse components, making the usage of general microtexture photometry more difficult. On the other hand, without using micro-texture photometry, the conventional circumferential 3D approaches only utilizes the geometric property of the target surface, compared to which, the proposed is able to reconstruct the target surface with finer detail.
The original contributions of this dissertation are threefold. To begin with, the specular component in the micro-texture photometry is investigated to propose the pixel-level 3D profiling. The intensities of the same pixel from different images, which are taken under different lighting conditions are different. The specular components are used to recover the surface normal of the corresponding surface patch of the target surface. Consequently, the proposed specular-photometry-based technique produces pixel-wise measurement on surface normal.
Furthermore, the conventional circumferential 3D profiling approach is extended with the proposed specular-photometry-based technique. The result of 3D profiling via the conventional approach is sparse due to its nature. On the other hand, the result of 3D profiling from the integration using the surface normal obtained from the proposed specular-photometry-based technique suffers from accumulative error. A new approach is then proposed to use the result from the conventional approach as global constraint, for the purpose of reducing the accumulative error. The proposed approach is able to achieve pixel-resolution globally bounded profiling because of the dense surface normal measurement from the proposed specular-photometry-based technique and the constraints from the conventional approach.
Lastly, a system is developed to apply the proposed circumferential specular-photometry-based 3D profiling approach. The developed system is not only able to acquire data and but also to provide different lighting conditions for both the specular-photometry-based technique and conventional approach using a digital single-lens reflex camera and different lighting devices. With a step motor to rotate the object for three hundred and sixty degrees, the system is able to achieve circumferential scanning / Doctor of Philosophy / This dissertation explains a novel approach to fulfill circumferential 3D profiling with high resolution for dark objects. With the proposed approach, the resolution is able to achieve micro-texture level. The high resolution measurement is achieved by investigating specular micro-texture photometry. As for dark objects, the specular components dominate the reflection. The usage of photometry is explained as follow. A small patch of a target surface yields different appearance under different illumination. For the material of the surface of dark objects, the surface reflects stronger specular components than diffuse components. The proposed approach utilizes this photometric property to recover the small patch's surface normal using its specular components. The recovered surface normal is then used to calculate the surface profile through integration. The conventional circumferential 3D profiling approach, which can only produce low-resolution measurement, is also adopted in the proposed approach to enhance its performance, as the integration method suffers from accumulative error. The result from the conventional approach serves as a global constraint to bound the final profiling result. A system is developed to apply the proposed circumferential specular-photometry-based 3D profiling approach, which is equipped with a step motor to rotate the object for three hundred and sixty degrees for the purpose of circumferential scanning. A series of numerical and experimental studies were conducted to validate the performance of the proposed approach. As it is shown in the result, the proposed approach is able to measure the tire tread with 31µm resolution.
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Evaluation of Circumferential Ankle Pressure as an Ergonomic Intervention to Maintain Balance Perturbed by Localized Muscular Fatigue of the Ankle JointSingh, Navrag B. 30 December 2005 (has links)
Application of pressure in the form of taping and bracing has been shown to improve proprioception, and inducing localized muscle fatigue at various musculatures has been shown to adversely affect postural control. However, the potential for pressure application to mitigate the effects of localized muscle fatigue on postural control has not yet been determined. This study investigated specifically the effects of circumferential ankle pressure (CAP) and induced ankle fatigue on postural control. Fourteen young participants (seven males and seven females) performed fatiguing sub-maximal isotonic plantar flexion exercises on an isokinetic dynamometer, in the absence and presence of a pressure cuff (60 mm Hg) used to apply CAP. Proprioceptive acuity (PA) was determined using a passive-active joint position sense test, with categorical scores (low or high PA) used as a covariate. Postural sway during quiet standing was assessed using a force platform both pre- and post-fatigue as well as in the absence and presence of CAP. Application of CAP resulted in larger postural sway in individuals with low PA, and reduced postural sway in individuals with high PA. Fatigue effects on postural sway in individuals with low PA were more substantial as compared to individuals with high PA. CAP was found to be ineffective in mitigating the effects of fatigue on postural sway in individuals with lower PA. As a whole, the results suggest a potential for CAP as an ergonomic intervention in controlling fatigue-related fall incidents, though conclusive recommendations for use are not justified. / Master of Science
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Cardiovascular magnetic resonance deformation imaging by feature tracking for assessment of left and right ventricular structure and functionAugustine, Daniel January 2014 (has links)
Cardiac magnetic resonance (CMR) imaging is the gold standard imaging technique for assessment of ventricular dimensions and function. CMR also allows assessment of ventricular deformation but this requires additional imaging sequences and time consuming post processing which has limited its widespread use. A novel CMR analysis software package, ‘feature tracking’ (Tom Tec, Germany) can measure ventricular deformation directly from cine CMR images. This thesis seeks to further our understanding of the feasibility of feature tracking to assess myocardial deformation and volumetric measures. Chapter 3 validates normal ranges for deformation parameters and compares values against traditional tagging measures. The work identifies global circumferential strain measures as being the most reproducible. In chapters 4 and 5, feature tracking values for left and right ventricular strain are compared with echocardiography derived speckle tracking indices of deformation. For left ventricular (LV) parameters, circumferential and longitudinal strain are most consistent and for the right ventricular (RV) measures, assessment of free wall strain using feature tracking shows promise and with modifications in algorithms is likely to further improve in the future. Chapter 6 assesses the ability of feature tracking to measure diastolic function. The results show that radial diastolic velocities and longitudinal diastolic strain rates can predict diastolic dysfunction (as diagnosed by echocardiography) with acceptable levels of sensitivity and specificity, particularly when used in combination. 11 The use of feature tracking to provide automated measures of ventricular volumes, mass and ejection fraction is assessed in chapter 7. Feature tracking in this context shows acceptable correlation but poor absolute agreement with manual contouring and further adjustments to algorithms is necessary to improve its accuracy. This work offers insights into the use of feature tracking for the assessment of ventricular deformation parameters. It is a technique with advantages over CMR tagging methods and given the speed of post processing has the potential to become the CMR preferred assessment for strain quantification in the future.
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Wave Interactions with Arrays of Bottom-Mounted Circular Cylinders: Investigation of Optical and Acoustical AnalogiesBaquet, Aldric 2010 August 1900 (has links)
Wave scattering by arrays of cylinders has received special attention by many authors and analytical solutions have been derived. The investigation of optical and acoustical analogies to the problem of interaction of water waves with rigid and flexible cylinder arrays is the main focus of this thesis. In acoustics, a sound may be attenuated while it propagates through a layer of bubbly liquid. In fact, if the natural frequency of the bubbles is in the range of the wave periods, the attenuation becomes more evident. The ultimate objective of the research described herein is to determine if this phenomenon may also be found in the interaction between water waves and arrays of flexible cylinders.
In a first approach, arrays of rigid cylinders are studied in shallow water. The array is treated as an effective medium, which allows for the definition of reflection and transmission coefficients for the array, and theories from Hu and Chan (2005) associated with the Fabry-Perot interferometer are compared against direct computations of wave scattering using the commercial code WAMIT. Reflection and transmission coefficients from WAMIT are evaluated by applying a Maximum Likelihood Method. The results from WAMIT were found to be in good agreement with those obtained from the effective medium theory. Due to observed inconsistencies for short wave periods and small incident angles, the effective width of the medium is defined and corrected.
For the case of a flexible cylinder, generalized modes corresponding to deformations of the cylinder's surface are formulated and added to WAMIT's subroutine. Equations of motion are derived from the theory of vibration for thin shells and mass and stiffness matrices are defined. The objective is to maximize wave attenuation from the array of flexible cylinders. Therefore, the natural periods of the "breathing" mode for these cylinders is set in the range of the studied wave periods. Then, material properties, as well as mass and stiffness matrices, are chosen to achieve this effect.
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Effect Of Fiber And Resin Type On The Axial And Circumferencial Tensile Strength Of Fiber Reinforced Polyester PipeGokce, Neslihan 01 September 2008 (has links) (PDF)
In this study, the aim is to investigate the stiffness, longitudinal tensile strength and circumferential tensile strength of short fiber reinforced polyester composite pipes produced by centrifugal casting production method. To achieve this aim, theoretical calculation of modulus of elasticity of pipes was done and then test program was carried out on pipe samples produced with three different resin types which were orthophthalic, isophthalic and vinyl ester resin and three different fiber types which were E glass fiber, ECR glass fiber and basalt fiber. The tests were performed according to ISO (International Organization for Standardization) standards.
When resin type and fiber type effect on the fiber reinforced polyester pipe samples were evaluated, calculated elastic modulus values were in accordance with the test results.
According to the experimental test data, which were used to evaluate the effect of resin type on fiber reinforced polyester pipe properties, there is not a significant difference was observed in the stiffness, longitudinal and circumferential tensile strength test results of pipes having different resin types. In other words, there was not a significant effect of resin type on the stiffness, longitudinal tensile strength and circumferential tensile strength of short fiber reinforced pipes produced by centrifugal casting method.
According to the experimental test data, which were used to evaluate the effect of fiber type on the properties of fiber reinforced polyester pipe, basalt fiber reinforced pipe samples showed higher mechanical performance over E glass fiber and ECR glass fiber reinforced pipes. However, the test results of basalt reinforced polyester pipe were not as good as the individual properties of basalt fiber.
Finally, by comparing the basalt fiber reinforced pipe samples having almost the same stiffness and tensile test results as E glass fiber reinforced pipe samples, the gain in fiber and resin amount were investigated. Basalt fiber reinforced pipes were slightly lighter and thinner than E glass fiber reinforced pipes. However, the decrease in the amount of the fiber and resin in basalt reinforced pipe did not result in an overall cost reduction.
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Protótipo robótico de baixo custo utilizado como ferramenta para o ensino de MatemáticaMedeiros Neto, Manoel Sátiro de 16 June 2017 (has links)
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Previous issue date: 2017-06-16 / Educational Robotics offers a standout under school, due to your use as teaching tool. In mathematics, it covers a field of opportunities that awakens in students the ability to question, think and look for solutions. The dissertation presents a model of low-cost robotic unit, used as additional tool for teaching and learning of mathematics. The ro- bot was prototype in a 3D printer and together with electronic kit Arduino project was implemented an algorithm, able to provide algebraic calculations that when performed, describe a circuit composed of line segments and circumferential arcs, taken from a pro- posed activities. / A robótica educacional oferece um destaque no âmbito escolar, devido a sua utiliza¸c˜ao como ferramenta pedagógica. Na matem´atica, ela abrange um campo de oportunidades que desperta nos alunos a capacidade de questionar, pensar e procurar soluções. Esta dissertação apresenta um modelo de robóotica de baixo custo, utilizado como ferramenta adicional ao ensino e aprendizagem da Matemática. O robô foi prototipado em uma impressora 3D e junto com kit de eletrônica do projeto Arduino foi implementado um algoritmo, capaz de proporcionar cálculos algébricos que ao serem realizados, descreve um circuito composto por segmentos de reta e arcos de circunferência, tomados a partir de uma proposta de atividades.
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