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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.
301

An Analytical Study On Minimum Confinement In Spiral Columns

Ozkaya, Cenan 01 July 2005 (has links) (PDF)
ABSTRACT AN ANALYTICAL STUDY ON THE MINIMUM CONFINEMENT IN SPIRAL COLUMNS &Ouml / zkaya, Cenan M.S., Department of Civil Engineering Supervisor: Prof. Dr. G&uuml / ney &Ouml / zcebe Co-Supervisor: Prof. Dr. Ugur Ersoy July 2005, 135 pages The minimum spiral ratio equation given in the codes is derived by equating the strength at the second peak to the strength at the first peak for spiral columns tested under uniaxial load. In this study, specimen behavior under combined bending and axial load was taken as basis while deriving proposed equations. Analyses were carried out by using a Moment-Curvature program. For normal strength concrete, one regression and one simplified equation giving minimum spiral ratio are proposed. Difference between two equations arises from the number in front of (Ac/Ack). In regression equation, this number is calculated by means of a function. In simplified equation, this number is a constant. For high strength concrete, a different regression equation is proposed which is valid for concrete strengths up to 95 MPa. Simplified equation proposed for normal strength concrete is also proposed for high strength concrete up to concrete strengths of 120 MPa. It was found that / (i) Simplified equation proposed for normal and high strength concrete yielded consistent results in the range of variables studied / (ii) Except some points, regression equations yielded consistent results / (iii) It is recommended to use simplified equation instead of regression and code equations since it yields more consistent results than code and regression equations. Keywords: Confined Concrete, Ductility, Moment-Curvature, Minimum Spiral Volumetric Ratio
302

An Analysis of Machining System Capability and Its Link with Machined Component Quality

Österlind, Tomas January 2013 (has links)
Machining components out of tolerances is of no use in competitiveproduction. The machining system sets the limitations of dimensionalaccuracy and surface quality of a machined component. The capabilityof the machining system describes these limits in terms of specifiedvalues. This thesis deals with machining system capability analysismainly focused on machine tool static and dynamic stiffness.The influence of stiffness and flexibility on machining systemcapability is analytically and experimentally investigated. Theexperimental work presented in the thesis complies with the theoriesand shows the relation between machine tool capability and theoutcome on the machine component.The concept of capability analysis by elastic linked system andthe currently available tools for such an evaluation is presented anddiscussed. The basis of elastic linked system analysis is the use ofmeasurements under loaded condition. The machine tool is loadedwith a known force creating a test condition closer to real machining,compared to current methods of unloaded machine tools. Twomeasurement tools for elastic linked system capability analysis areexplained in the thesis: Loaded Double Ball Bar and ContactlessExcitation and Response System.The thesis consists of an analytical base and an experimental casestudy on spiral bevel gear face milling. The experiments are discussedand compiled with the given theories. / <p>QC 20130513</p>
303

An investigation into a dramatic writing toolset for the creation of a new work of drama

Player, Glen J. January 2007 (has links)
In this exegesis I have attempted to formulate a primary toolset for dramatic writing that I can apply to create dramatic structure in plays, the chief example being my play Albatross (included herein). This toolset is contingent upon Aristotle's basic tenet of drama, that "tragedy is an imitation of an action" (2002: 10). This exegesis theorises that the work of modern writers on drama such as Spencer, Packard, Catron, Lamott, See, Hicks and many others, fundamentally accords with Aristotle on this point, such that the tools they espouse can collectively be considered a standard set for dramatic writing. Beyond this, my research has led me to believe that there is a primary subset of tools specific to creating dramatic structure. These tools, formulated from dramatic theory, best capture my own way of thinking about my writing practice. I divide them into two types: the first, tools of creation, comprise Theme and Values; Character and their Values; Characters and Action; Character Orchestration and Obstacles; and Event and Significant Change. The second, tools of evaluation, are Passivity; Stakes; and Premise. Together these eight tools have been responsible for creating dramatic structure in the play, Albatross.
304

A Novel Methodology To Classify The ADSS Cable Ranking

January 2011 (has links)
abstract: All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used over these ADSS cables. These dampers are installed near the armor rods, where the presence of leakage current and dry band activity is more. The effect of dampers on dry band activity is investigated by conducting experiments on ADSS cable and dampers. Observations made from the experiments suggest that the hydrophobicity of the cable and damper play a key role in stabilizing dry band arcs. Hydrophobic-ity of the samples have been compared. The importance of hydrophobicity of the samples is further illustrated with the help of simulation results. The results indi-cate that the electric field increases at the edges of water strip. The dry band arc-ing phenomenon could thus be correlated to the hydrophobicity of the outer sur-face of cable and damper. / Dissertation/Thesis / M.S. Electrical Engineering 2011
305

Influence of Heterogeneities on Waves of Excitation in the Heart

Baig-Meininghaus, Tariq 07 September 2017 (has links)
No description available.
306

Dynamical Imprint of Dark Matter Halo and Interstellar Gas on Spiral Structure in Disk Galaxies

Ghosh, Soumavo January 2017 (has links) (PDF)
The topic of this thesis deals with the spiral structure in disk galaxies with a specific aim of probing the influence of the dark matter halo and the interstellar gas on the origin and longevity of the spiral arms in late-type galaxies through theoretical modeling and numerical calculations. The basic theoretical model of the galactic disk used involves gravitationally-coupled two-component system (stars and gas) embedded in a rigid and non-responsive dark matter halo, i.e., the static potential of the dark matter is used in the calculations. However, at places, depending on the nature of the problem addressed, the disk is treated as consisting of only stellar component or only gas component followed by proper justifications for the assumptions. The disk is rotationally-supported in the plane and pressure-supported perpendicular to the plane of the disk. The first part of the thesis involves searching for the dynamical effect of dark matter halo on small-scale spiral structure in dwarf low surface brightness (LSB) galaxies and also some dwarf ir-regular galaxies which host an extended H I disk. In both cases, the rotation curves are found to be dominated by the contribution of the dark matter halo over a large radial distance, starting from the inner regions of the galaxies. The next part of the thesis deals with the investigation of the possible effect of the interstellar gas on the persistence is-sue and the pattern speeds of the spiral structure in the disk galaxies. The last part of the thesis involves in studying the dynamical effect of dark matter halo on large-scale spiral structure. Following is the layout of the thesis. Chapter 1 gives a general introduction to the topic of spiral structure of late-type disk galaxies, followed by a broad overview of the theoretical development of the topic and the present status of the topic. Then the thesis starts with studying the small-scale spiral features and evolves to studying the large-scale spiral features seen in disk galaxies in the following way: Chapters 2 & 3 deal with the effect of dark matter halo on small- scale spiral structure. Chapters 4 & 5 focus on the dynamical effect of the interstellar gas on the spiral structure using the local dispersion relation. Chapters 6 & 7 discuss the possible effect of dark matter halo on large-scale spiral structure in disk galaxies. Chapter 8 contains the summary of results and future plans. Effect of dark matter halo on small-scale spiral structure The spiral arms in the disks of galaxies are often broken into several smaller parts or patches that create a messy visual impression when viewed from a ‘face-on’ configura-tion. They are generally termed as ‘small-scale’ or flocculent spiral arms. Several stud-ies showed that the small-scale spiral arms are basically material arm, i.e., they can be thought of as ‘tubes’ filled with stars and gas. Spiral arms are known to participate in the secular evolution of the disk galaxies. Since disk galaxies are believed to reside within a halo of dark matter, therefore a detailed understanding of possible effects of dark matter halo on the spiral arms is necessary. In Chapter 2, we investigate the effect of dark matter halo on small-scale spiral fea-tures in the disks of LSB galaxies. Modeling the mass distribution within a galaxy from the rotation curve of a typical small LSB galaxy reveals the generic fact that for most of the radii, dark matter halo dominates over the stellar disk. This trend is found to be true from the very inner regions of an LSB disk which in turn makes the LSBs a suitable laboratory for probing the effect of dark matter halo on the dynamics of disk galaxies. Following a semi-analytic approach, and using the observationally measured input pa-rameters for a typical superthin LSB galaxy, UGC 7321, we showed that the dominant dark matter halo suppresses the small-scale spiral structure in the disk of UGC 7321. Since UGC 7321 possesses features typical of a LSB galaxy, we argued that this finding will also hold true for other typical LSBs. The result is at par with the observational evi-dences for the lack of prominent, strong small-scale spiral structure in LSB galaxies. In Chapter 3, we employed the similar techniques for probing the effect of dark matter halo on small-scale spiral structure, except this time we took five dwarf irregular galaxies with an extended H I disk as the sample for our investigation. The main im-portant difference between these dwarf irregular galaxies with the earlier LSB galaxies is that for these dwarf irregular galaxies with extended H I disk, the largest baryonic con-tribution comes from the interstellar gas (mainly H I ), and not from the stars (as seen in LSBs). The extended H I disks of these galaxies allow one measure the rotation curve, and hence modeling the dark matter halo parameters for a large radial range from the galactic center. Here also the rotation curves are found to be dominated by dark matter halo over most of the disk, thus providing yet another ‘laboratory’ for testing the dynam-ical effect of dark matter halo on the dynamics of the disks. Using the observed input parameters for five such dwarf irregular galaxies, we showed that the dense and com-pact dark matter halo is responsible for preventing strong small-scale spiral structure in these galaxies, which is in fair agreement with the observations. Dynamical effect of interstellar gas on longevity of spiral arms Any late-type disk galaxy contains a finite amount of interstellar gas along with the stel-lar component. The atomic hydrogen (H I ) constitutes the bulk of the interstellar gas along with the molecular hydrogen (H2), ionized hydrogen (H I I ), and a trace amount of heavy elements like helium. The mass fraction present in the interstellar gas in disk galaxies is found to vary with the Hubble sequence, with the amount of interstellar gas increasing from Sa type to Scd type of galaxies. Due to the lower value of velocity disper-sion as compared to that of stars, gas is known to have a larger destabilizing effect in the disk. Therefore, the natural question arises about what possible role the interstellar gas could play in the origin and the persistence issue of spiral arms. In Chapter 4, we explored how the interstellar gas could influence the longevity of the spiral arms in late-type disk galaxies by treating the spiral structure as density waves in the disk. The disk is modeled as a gravitationally coupled stars plus gas (two-component) system, where the stars are modeled as a collisionless system and the gas treated as a fluid system. Using the appropriate local dispersion relation for the above mentioned model for the disk of galaxy, we calculated the group velocity of a wavepacket of density wave and then studied the variation of the group velocity with increasing amount of interstellar gas in the system. We showed that the group velocity of a wavepacket in a Milky Way-like disk galaxy decreases steadily with the inclusion of gas, implying that the spiral pattern will survive for a longer time-scale in a more gas-rich galaxy by a factor of few. In Chapter 5, we investigated the role of interstellar gas in obtaining a stable den-sity wave corresponding to the observed pattern speed for the spiral arms. The under-lying local dispersion relation remains same as that is in Chapter 4. Using the observa-tionally measured pattern speed and the rotation curves for three late-type disk galaxies we showed that the presence of interstellar gas in necessary in order to maintain a stable density wave corresponding to the observed values for pattern speeds. Also we proposed a method to determine a range of pattern speed values at any particular radius, corre- sponding to which the density wave can be stable. We applied this method to the same three late-type galaxies which we used in the earlier part of this chapter. We found that, for these three galaxies, the observed pattern speed values indeed fall in the predicted range. Imprint of dark matter halo on large-scale spiral structure Along with the small-scale spiral arms, there also exists another type of spiral arms – the large-scale spiral structure, like what we see M 51 or in NGC 2997, which occupy almost the entire outer optical disk in the galaxy. These spiral arms are termed as ‘grand-design’ spiral structure. One of the competing theories, namely, Density wave theory proposes that the large-scale structure is basically a density wave in the disk and the pattern ex-hibits a rigid-body rotation with a definite constant pattern speed. In the earlier part this thesis (Chapters 2 & 3), it was shown that the small-scale spiral structure gets damped by the dominant dark matter halo. Therefore, a natural question arises whether dominant dark matter plays any role on these large-scale spiral structure; and if yes, to what extent it affects the large-scale spiral structure. In Chapters 6 & 7, we investigated how the large-scale structure in disk galaxies gets affected when the disk galaxy hosts a dark matter halo that dominates over most of the disk regions. We again chose the LSB galaxies as laboratory for this study. In Chapter 6, we modeled the stellar component as a fluid system and in Chapter 7, we treated the stellar system as more realistic collisionless system. In both cases, global spiral modes are identified from the appropriate dispersion relations via a novel quantization rule, and they are used as a ‘proxy’ for the large-scale spiral structure. Using the input pa-rameters for UGC 7321, in Chapter 6 we showed that the fluid representation of stellar system failed to make an impression in suppression of the global spiral modes. However, when stellar component is treated as a more realistic collisionless system, we found that the dark matter halo suppresses the large-scale spiral features as well in the disks of LSB galaxies, in fair agreement with the observations. Finally, in Chapter 8, the thesis concludes with a summary of main results and a brief discussion of the scope for future work.
307

Objektová modifikace herního principu / Building Modifications to the Game Principle

MAURER, Ivan January 2013 (has links)
The teoretic part comes from the historical overview of use of spiral as main motive in the process of forged bars from romanesque style up to now overlap to free creation of contemporary artists. Concept of the game subjekt comes from combination of craft technology with motive of spiral to the model object for working game. The result is game SPIRAL ? Man, do not be angry!
308

Estudo por tomografia computadorizada helicoidal com múltiplas fileiras de detectores em vítimas de ferimento por arma de fogo abdominal / Multi-detector row computed tomography study in abdominal gunshot wound victims

Ernesto Lima Araujo Melo 03 June 2009 (has links)
O principal objetivo deste estudo foi testar a capacidade da tomografia computadorizada helicoidal com múltiplas fileiras de detectores (TCMD) na identificação/exclusão de lesões em vítimas de ferimento por arma de fogo (FAF) abdominal. Os achados de imagem foram comparados aos cirúrgicos em todos os pacientes da amostra. A TCMD demonstrou elevada acurácia na avaliação de órgãos sólidos, vísceras ocas, grandes vasos e diafragma. Quase a metade dos pacientes (45,2%) não exibiu lesões que necessitassem obrigatoriamente de correção cirúrgica. A TCMD mostrou-se excelente na avaliação dos pacientes da amostra, podendo contribuir com informações importantes ao manejo de vítimas de FAF abdominal. / The main objective of this study was to test the ability of multi-detector row computed tomography (MDCT) in the identification/exclusion of lesions in abdominal gunshot wound (GW) victims. The imaging findings were compared with the surgical ones in all of the studied patients. MDCT demonstrated elevated accuracy in the evaluation of solid organs, hollow viscus, great vessels, and diaphragm. Almost half of the patients (45.2%) did not show lesions requiring obligatory surgical interventions. MDCT showed to be excellent in the evaluation of the studied patients, and can contribute with important information for the management of abdominal GW victims.
309

Avaliação da perfusão miocárdica de estresse com dipiridamol pela tomografia computadorizada com 64 colunas de detectores / Dipyridamole stress myocardial perfusion evaluation by 64 detector-row computed tomography

Roberto Caldeira Cury 16 February 2011 (has links)
A angiotomografia de múltiplos detectores (TC) é um exame útil no diagnóstico de doença arterial coronariana (DAC). Recentemente, a TC foi associada à perfusão miocárdica com estresse (PTC) para detectar DAC. O objetivo é comparar a perfusão miocárdica da TC, após estresse com dipiridamol, com a cintilografia miocárdica (SPECT) na detecção de estenose coronariana significativa (>70%), usando o cateterismo (CATE) como método de referência. Trinta e seis pacientes (62±8,0 anos, 20 homens) com suspeita de DAC e com SPECT positivo em menos de 2 meses foram submetidos a um protocolo de TC para avaliação da PTC e angiografia pela tomografia computadorizada (ATC). TC foi realizada em um equipamento de 64 detectores (Aquillion 64, Toshiba), com uma primeira aquisição com os seguintes parâmetros:100mA,120Kv, 32x1mm colimação e 60ml de contraste a 3ml/s, após estresse com dipiridamol (0,56mg/Kg/4min), seguida de uma aquisição de repouso/ATC após aminofilina e metoprolol (270-400mA, 120Kv,64x0,5mm e 80 ml de contraste a 5ml/s). Observadores cegos e independentes, sem conhecimento prévio dos dados clínicos ou dos exames, realizaram análise visual e quantitativa da perfusão e angiotomografia, além de análise angiográfica quantitativa (QCA) para avaliação do CATE. Todos os pacientes completaram o protocolo sem efeitos adversos com dose de radiação média de 14,7 ± 3,0 mSv e exames interpretáveis. PTC foi positiva em 27 de 36 pacientes (75%). Dos nove casos (25%) com discordâncias (PTC negativa e SPECT positivo), 6 pacientes tinham ATC ou CATE normal e 2 tinham estenose coronariana menor que 50%. Um apresentava stent pérvio e o outro um ramo diagonal com redução luminal de 50%.O terceiro paciente apresentava uma oclusão do ramo ventricular posterior da artéria coronária direita com circulação colateral detectado pela ATC e confirmado pelo CATE. A comparação entre a PTC e o SPECT em uma análise por paciente mostrou boa concordância (Kappa =0,53;p<0,001). Em 26 pacientes com CATE, como referência, os valores diagnósticos foram sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e acurácia para a PTC 88,0; 79,3; 66,7; 93,3; 82,1% e para o SPECT 68,8; 76,1; 66,7; 77,8 e 73,1%, respectivamente. A perfusão miocárdica de repouso e estresse após dipiridamol na avaliação de doença aterosclerótica coronariana, associada à angiografia pela tomografia é factível e os resultados foram similares ao do SPECT. A combinação da informação anatômica e perfusional permite identificar os casos positivos do SPECT, sem estenose coronariana significativa. / Multidetector computed tomography is a useful method for the diagnosis of coronary artery disease. Recently, myocardial stress CT perfusion (CTP) was shown to detect myocardial ischemia. Our main objective was to evaluate the feasibility of dipyridamole stress CTP and compare to SPECT perfusion to detect significant coronary stenosis using conventional angiography (CCA) (stenosis >70%) as reference method. Thirty-six patients (62.0±8.0 years old, 20 males) with suspected CAD and < 2 months prior positive SPECT underwent a customized multidetector-row computed tomography (MDCT) protocol with rest/stress myocardial perfusion evaluation and CTA. MDCT was performed in a 64 scanner (Aquillion 64, Toshiba) with stress perfusion after 0.56mg/kg/4min of dipyridamole (100mA, 120 kV, collimation-32 x 1 mm and 60 ml of iodinated contrast) followed by aminophyline and metoprolol infusion prior to a second rest perfusion/CTA acquisition (270-400mA, 120 kV, collimation-64 x 0,5 mm and 80 ml of iodinated contrast). Independent blinded observers with no knowledge of clinical data or other exams performed visual and quantitative analysis of CTP, CTA, SPECT and quantitative coronary angiography (QCA) analysis, that was performed on CCA. All 36 patients completed the CT protocol with no adverse events, mean radiation dose of 14.7 ± 3.0 mSv and with interpretable scans. CTP was positive in 27 of 36 patients (75%). From the 9 (25%) disagreements with normal CTP and positive SPECT, 6 patients had normal CCA or CTA and 2 had no coronary stenosis > 70 %. One had patent stents and the other had a diagonal branch with mild luminal reduction at CCA. The remaining patient had an occluded right posterior lateral branch with collateral flow detect by CTA and confirmed by CCA. Good agreement was demonstrated between CTP and SPECT on a per-patient analysis (kappa 0.53). In 26 patients using CCA as reference, sensitivity, specificity, positive predictive value, negative predictive values and accuracy for CTP were 88.0, 79.3, 66.7, 93.3%, 82,1% and for SPECT 68.8, 76.1, 66.7, 77.8% and 73,1% respectively. Rest and dipyridamole-stress computed tomography myocardial perfusion is feasible and results are similar to SPECT scintigraphy. The combined anatomical information provided by computed tomography coronary angiography may allow identification of false-positives on perfusion scans.
310

Desenvolvimento e validação de uma ferramenta computacional para mensuração das curvaturas da coluna vertebral. / Development and validation of computational tool for measuring of curves of the spine

André Luis Alarcon do Passo Suaide 13 November 2008 (has links)
A coluna vertebral desempenha um papel importante no dia a dia oferecendo suporte necessário à movimentação do tronco além da locomoção do ser humano, sendo o seu funcionamento diretamente relacionado com a qualidade de vida; sua disposição e articulação das vértebras proporcionam estabilidade e flexibilidade à coluna vertebral, atributos necessários para o equilíbrio do ser humano. A hipercifose torácica, hiperlordose lombar e escoliose são as patologias posturais mais comuns e podem ser diagnosticadas pela mensuração do ângulo da curvatura da coluna vertebral. Comumente a radiografia é utilizada como método para a mensuração de tais ângulos, porém, além de ser um método caro, é altamente invasivo por causa da exposição à radiação, por isso não é aconselhado praticá-lo muitas vezes, sendo o acompanhamento do tratamento difícil de ser feito. Há diversos métodos não invasivos, porém não combinam praticidade, baixo custo e análise tridimensional da curvatura, sendo eficazes em mensurar apenas a coluna no plano sagital. Por esses motivos, para o uso clínico, o profissional de saúde necessita de um método barato, confiável, prático, que atenda suas necessidades e não invasivo para a mensuração da curvatura da coluna vertebral. O objetivo desse trabalho foi desenvolver e validar com a Cinemetria composto de cinco câmeras infravermelhas uma ferramenta computacional (LoB Analytics) para mensurar esse ângulos, o software terá código aberto e uso gratuito. A média de todos os ângulos obtida pela Cinemetria foi de 43,4±18,5º e pelo LoB Analytics foi de 43,9±17,7º, com uma correlação muito forte de 0,98. Foram feitas regressões lineares que confirmaram que ângulos calculados pelo LoB Analytics são tão confiáveis quanto os calculados pela Cinemetria, que é um método bastante utilizado hoje em dia. Os grandes diferenciais do LoB Analytics sobre a Cinemetria são: o seu baixo custo e a praticidade de usá-lo em laboratórios e clínicas. / The spine has an important role day by day offering the necessary flexibility for movement of the trunk besides support and locomotion of humans and being is directly related to the quality of life. The provision and articulation of the vertebrae are responsible for the stability and flexibility of spine attributes necessary for the balance. The thoracic hiper and hypo kyphosis, lumbar hiper and hypo lordosis and scoliosis are the most common postural pathologies and can be diagnosed by measuring the angle of the curvature of the spine. The radiographic method has been the most popular method for such measurement, however, it is an expensive method and also invasive (because its exposure to radiation), it is not the method more indicated to be used repeatedly, being the monitoring of treatment difficult to be done. There are several noninvasive methods but they do not combine practicality, low cost and three-dimensional analysis of the spine curvature, and they are effective in measuring the spine only in the sagittal plane. For these reasons, the health professional needs a method that has low cost, reliable, practical and noninvasive methods for measurement of the curvature of the spine. The goal of this work was develop and validate, with motion capture system (Cinemetria), a computational tool for this measurement (LoB Analytics), which will be free and open source. The mean of all Cinemetria angles was 43,9±18,5º and LoB Analytics angles was 43,9±17,7, with a very strong correlation coefficient of 0,98. Linear regressions confirmed that LoB Analytics angles are as reliable as those calculated by Cinemetria, which is a method widely used today. The differentials of LoB Analytics on Cinemetria are: low cost and practicality of using it in laboratories and clinics.

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