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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.
41

Characterization of coupled body response in random sea

Xie, Chen 25 April 2007 (has links)
The frequent use of two or more closely positioned vessels during offshore operations makes the study of multi-body hydrodynamics an important topic, especially for the design of deepwater offshore systems. This research investigation studies the response behavior of a coupled mini-TLP / barge system in both head and beam sea conditions. The design sea conditions were selected to represent the combined wind, wave and current conditions for a target location off the coast of West Africa. Both the mini-TLP and the barge were designed to have independent mooring systems. Coupling between the two vessels is introduced through a connection consisting of two breast lines and a fender system. This connection is designed to restrain the horizontal movements of the two vessels while keeping a constant distance between them and avoiding collisions. The main focus of this study is to analyze the experimental data obtained during the model testing, especially the motions of the two bodies and the values related to the fender system, in order to characterize the behavior of the uncoupled and coupled system configurations. A statistical approach is used for the data analysis and interpretation. Statistical parameters are used to provide an overall characterization of system behavior, and Gaussian and Weibull distribution functions are utilized to detect the importance of non-linearity in the data with particular attention to extreme values. Correlations between the two vessels in time domain and frequency domain are investigated. In addition, auto and cross spectrum analyses of the data are used to contrast the motion behavior of the uncoupled and coupled configurations. It is shown that the connection system reduces the horizontal vessel motions; however the forces exerted on the fender system show significant variation depending on sea heading conditions.
42

Inkluderad på lika villkor : En retorisk analys av Socialdemokraternas invandringspolitik 1990 och 2013

Mambari, Makwan January 2014 (has links)
The purpose of my study is to study Social Democrats immigration policy over the period 1990 and 2013. My material consists of party programs and motions that social democracy has raised in Parliament. As a research method I used McGee´s ideograph theory. I use a cluster analysis inspired by Kenneth Burke to analyze the meaning of those found ideographs. I also present and use Bitzers rhetorical situation in my analyze With help of Burke´s rhetorical situation I could see how the Social Democrats' rhetorical approach to immigration policy in the different periods in society. My investigation of the Social Democratic Party program and motions / propositions revealed the following ideographs: Democracy, solidarity, equality and freedom. keywords that went to associate to the ideographs relating to immigration policy was school, adults, racism, equal rights, democratic freedom. Rhetorical could be interpreted as a way to show that in year 2013 the party stands behind a more solidarity, equality of human beings in society. Groups such as migrants and refugees should not stick out like a social group, but the group should be included in the collective Sweden.
43

Απόκριση του μοντέλου ολίσθησης Newmark σε σεισμικές διεγέρσεις εγγύς πεδίου

Πράπα, Ευγενία 05 February 2015 (has links)
Μεγάλος αριθμός έργων πολιτικού μηχανικού αναπτύσσουν μηχανισμούς ολίσθησης. Η ευστάθεια πρανούς που καταπονείται από σεισμικές διεγέρσεις είναι ένα πρόβλημα που απασχόλησε πληθώρα μελετητών κατά την διάρκεια των χρόνων και οδήγησε στην ανάπτυξη διαφόρων μεθόδων για την εκτίμηση των μόνιμων παραμορφώσεων με το πέρας της κίνησης. Σκοπός της παρούσας εργασίας είναι να μελετήσει το φαινόμενο της ασύμμετρης ολίσθησης πρανούς προσομοιώνοντάς το, με ένα μοντέλο που αναπτύχθηκε το 1965 από τον Newmark και να καταδείξει το μέγεθος των μετατοπίσεων που αναπτύσσονται , το πώς η πολικότητα του σεισμού επηρεάζει την συμπεριφορά του πρανούς καθώς και την περεταίρω μελέτη που επιβάλλεται να διεξαχθεί. Αναπτύσσεται αναλυτικά η λογική της κίνησης καθώς και οι τρόποι προσέγγισης του προβλήματος, μία λύση κλειστής μορφής και μία με το μοντέλο Bouc- Wen, διερευνούνται οι παράμετροι που επηρεάζουν το πρόβλημα και τέλος παρατίθενται αφενός τα αποτελέσματα συγκριτικά με αυτά της βιβλιογραφίας και αφετέρου των αναλύσεων πλήθους σεισμικών διεγέρσεων εγγύς πεδίου. / Numerous civil engineer’s applications develop sliding mechanisms. Slope’s stability under seismic excitations is a problem that was investigated by several researchers in recent years and led to the development of various methods for the estimation of permanent displacement by the end of the motion. The current study examines the slope’s asymmetric sliding by Newmark’s analogue, calculates the residual slippage, shows how polarity affects slope’s behavior and suggests further analysis. The concept of behavior is analysed thoroughly, the two approaches of the problem are presented (a closed form solution and a Bouc-Wen Model analysis), the parameters of the problem are investigated and eventually, a literature comparison and analysis results are listed.
44

The hydrodynamics of ship sections entering and exiting a fluid

Barringer, Ian Edward January 1998 (has links)
We study the hydrodynamics of wedge,knuckle and box cross-sectional profiles undergoing transient extreme motions, in particular forced entry and exit at constant velocity or acceleration. Extensive data for the forces, pressures and free-surface profiles is generated by an extension of a fully-nonlinear boundary-integral method. The code is thoroughly checked by altering the time step and particle spacing on the bodies and Lagrangian free-surface markers, and, for the wedge,checking self-similarity for the infinite Froude number (gravity free) constant velocity entry. Difficulties with inviscid flow around sharp corners are discussed. Results for exit are of particular interest since no zero-gravity approximation is valid and this precludes application of existing slamming theories in reverse. Whilst entry generally gives larger free-surface motions (spray jets), pressures and hence forces, calculation of exit is needed for the velocity of subsequent slamming and so is of practical interest too. These results are compared with an approximate analytical model, based on Schwarz-Christoffel transformations to calculate the infinite-frequency added mass of the cross-section below the mean water line. For constant acceleration of both entry and exit, the analytical theory is good during the early stages of motion. Later, the assumption of an undisturbed mean water level is clearly violated; the exact calculations show a large amount of draw-down (up-rise), the free-surface making contact with the body well below (above) the mean water level. We therefore examine the effect of reducing (increasing) the submerged body volume to take account of this, which prolongs the agreement between the results considerably and therefore might be used to improve practical calculation of extreme ship motions using existing strip theory codes. Full sets of numerical data input/output are provided in the appendices, together with some mathematical details. We also speculate on the possible application of John's equation to wedge entry.
45

Novel applications for hierarchical natural move Monte Carlo simulations : from proteins to nucleic acids

Demharter, Samuel January 2016 (has links)
Biological molecules often undergo large structural changes to perform their function. Computational methods can provide a fine-grained description at the atomistic scale. Without sufficient approximations to accelerate the simulations, however, the time-scale on which functional motions often occur is out of reach for many traditional methods. Natural Move Monte Carlo belongs to a class of methods that were introduced to bridge this gap. I present three novel applications for Natural Move Monte Carlo, two on proteins and one on DNA epigenetics. In the second part of this thesis I introduce a new protocol for the testing of hypotheses regarding the functional motions of biological systems, named customised Natural Move Monte Carlo. Two different case studies are presented aimed at demonstrating the feasibility of customised Natural Move Monte Carlo.
46

Unconstrained humeral elevation exposure in occupational settings

Amasay, Tal, 1968- 09 1900 (has links)
xvi, 128 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / There were two primary goals of this work. The first goal was to investigate humeral and scapular kinematics in a simulated workplace environment. The second goal was to validate a triaxial accelerometer (Virtual Corset) for the collection of humeral elevation exposure data in an occupational setting. To achieve the first goal, healthy subjects were asked to perform constrained and functional humeral elevation motions. Differences were observed in scapular kinematics. In addition, the variability between constrained arm elevation and functional overhead tasks was found to be similar. Therefore, to compare scapular kinematics in an occupational group (dental hygienists) a functional work related task was determined to be more appropriate. The dental hygienists performed teeth instrumentation on simulated patients' with both big and average chest girth in a simulated work environment. Dental hygienist's humeral elevation and scapular upward rotation angles were found to be higher while working on the big chest girth manikin. These differences may increase dental hygienists susceptibility for musculoskeletal disorders. To achieve the second goal, an in-vitro comparison of angles measured with the Virtual Corset and an inclinometer was conducted under static conditions. Under dynamic conditions the Virtual Corset was compared to a potentiometer, in a pendulum setting. It was found that the Virtual Corset can accurately reconstruct elevation angles under static conditions, root mean square error less than 1[white square]. Under dynamic conditions, the error size was related to the angular velocity and acceleration, and the radius of rotation. To further investigate the Virtual Corset's ability to measure exposure parameters in-vivo the Virtual Corset was compare to a magnetic tracking device. To do so dental hygienists performed flossing tasks in a simulated work station. It was found that the Virtual Corset can be used to reconstruct elevation angles, with an acceptable angle error, and to identify exposure parameters in occupational settings similar to the one simulated in the present study. This dissertation includes unpublished co-authored material. / Adviser: Andrew R. Karduna
47

Ekonomiska män och omsorgsfulla kvinnor : En kvantitativ innehållsanalys av riksdagsmotioner

Ek, Marcus January 2018 (has links)
In many parts of the world women are still largely underrepresented in parliaments. Sweden is however one of the countries that have developed one of the more equal parliaments in the world. This progress has given rise to a question in women studies; how does a more equal representation affect the politics? Earlier studies on this field in Sweden was mainly done in the late 80’s and early 90’s and how the situation is today, being largely unknown. This thesis explores differences between men and women in the writing of motions. To identify these differences, a quantitative content analysis is conducted of all freestanding motions of 2015. As it turns out there is large differences between male and female commissioners both in regard to the participation as well as the content of the motions. For example, women write considerably less motions and men’s motions gets twice the amount of endorsements. / I många delar av världen är kvinnor fortfarande underrepresenterade i parlamenten. Sverige är dock ett av länderna i framkant vad det gäller en jämställd representation och många andra länder blir mer och mer jämställda. Denna utveckling har lett till att ett kvinnovetenskapligt problemområde utvecklats; hur påverkar en mer jämställd representation politiken som förs? Tidigare studier på området har framförallt genomförts under sent 80-tal och tidigt 90-tal och hur situationen ser ut idag är i stort sett outforskat. Denna uppsats undersöker skillnader mellan manliga och kvinnliga riksdagsledamöter i motionsskrivandet. För att identifiera skillnader så genomförs en kvantitativ innehållsanalys av fristående motioner från år 2015. Det visar sig att det finns stora könsskillnader både vad det gäller hur många motioner som skrivs och vad de handlar om. Kvinnor skriver bland annat betydligt färre motioner och mäns motioner får dubbelt så ofta någon form av bifall.
48

The HST Large Programme on ω Centauri. III. Absolute Proper Motion

Libralato, Mattia, Bellini, Andrea, Bedin, Luigi R., Edmundo Moreno D., Fernández-Trincado, José G., Pichardo, Barbara, Marel, Roeland P. van der, Anderson, Jay, Apai, Dániel, Burgasser, Adam J., Marino, Anna Fabiola, Milone, Antonino P., Rees, Jon M., Watkins, Laura L. 09 February 2018 (has links)
In this paper, we report a new estimate of the absolute proper motion (PM) of the globular cluster NGC 5139 (omega Cen) as part of the HST large program GO-14118+ 14662. We analyzed a field 17 arcmin southwest of the center of omega Cen and computed PMs with epoch spans of similar to 15.1 years. We employed 45 background galaxies to link our relative PMs to an absolute reference-frame system. The absolute PM of the cluster in our field is (mu(alpha) cos delta, mu(delta))=(-3.341. 0.028, -6.557 +/- 0.043) mas yr(-1). Upon correction for the effects of viewing perspective and the known cluster rotation, this implies that for the cluster center of mass (mu(alpha) cos delta, mu(delta))=(-3.238. 0.028, -6.716 +/- 0.043) mas yr(-1). This measurement is direct and independent, has the highest random and systematic accuracy to date, and will provide an external verification for the upcoming Gaia Data Release 2. It also differs from most reported PMs for omega Cen in the literature by more than 5 sigma, but consistency checks compared to other recent catalogs yield excellent agreement. We computed the corresponding Galactocentric velocity, calculated the implied orbit of omega Cen in two different Galactic potentials, and compared these orbits to the orbits implied by one of the PM measurements available in the literature. We find a larger (by about 500 pc) perigalactic distance for omega Cen with our new PM measurement, suggesting a larger survival expectancy for the cluster in the Galaxy.
49

Aglomerados abertos: determinação de parâmetros cinemáticos e fundamentais / Open clusters: fundamental and kinematic parameters determination.

Victória Flório Pires de Andrade 27 April 2007 (has links)
Nosso grupo tem dedicado atenção especial em manter o Novo Catálogo de Aglomerados Abertos e Candidatos Opticamente Visíveis (Dias et.al. [1] denominado comumente DAML02), que vem sendo continuamente atualizado com novos resultados vindos da literatura. Além de manter o catálogo, nosso grupo está constantemente produzindo novos resultados como movimentos próprios médios e determinação de probabilidades de pertinência de estrelas aos aglomerados estudados (Dias et. al. [2] [3] [4]), também descobrindo novos aglomerados abertos (Alessi et. al. [5]) contribuindo para o conhecimento da amostra de aglomerados abertos conhecida na nossa Galáxia. Neste trabalho nós apresentamos os primeiros resultados de um estudo cinemático e fotométrico de uma amostra de aglomerados abertos com distância e idade desconhecidas. Trata-se de uma amostra de 850 aglomerados originalmente listados na versão 2.3 do catálogo DAML02. As probabilidades de pertinência das estrelas na região de cada aglomerado foram determinadas através de métodos estatísticos conhecidamente eficazes como (Vasilevskis e Rach [6], Sanders [7] e Zhao e He [8] aplicados aos movimentos próprios individuais UCAC2 (Zacharias et.al.[9]). Conseqüentemente, os movimentos próprios médios dos aglomerados também foram estimados. Utilizando apenas as estrelas membro e dados fotométricos 2MASS (Skrutskie et.al.[10]) construímos os diagramas cor-magnitude para cada aglomerado que nos permitiram estimar parâmetros fundamentais dos aglomerados como distâncias, excessos de cor nas bandas do infravermelho e idades. A determinação desses parâmetros envolve o ajuste de isócronas a seqüência principal do aglomerado e a partir de valores iniciais ajustamos essas curvas para a obtenção dos valores de distâncias, excessos de cor e idades. Desenvolvemos com o objetivo de fornecer esses valores preliminares, um programa que usa apenas as estrelas com Tipo Espectral identificado no SIMBAD. Portanto, neste trabalho determinamos movimentos próprios e probabilidades de pertinência para 319 aglomerados. Desses, 32 apresentaram solução para os parâmetros fundamentais (distância, excesso de cor e idade) e segundo nossas análises para os casos inéditos, 11 aglomerados encontram-se na vizinhança solar. Os erros envolvidos estimados são totalmente coerentes com os erros do catálogo DAML02. / Our group has dedicate a special attention to maintain the New Catalogue of Optically Visible Open Clusters and Candidates (Dias et al.[1] hereinafter DAML02) that is being continuously updated with new results from the literature. Besides maintaining the catalogue, our group is actively producing new results such as the mean absolute proper motion and membership determination (Dias et. al. [2] [3] [4]) and discovering new open clusters (Alessi et al.[5]) contributing to complete the knowledge of the hole sample of open clusters in the Galaxy. In this work we present the first results of the kinematic and photometric study of the open clusters with unknown distance and age in DAML02. The membership probabilities of the stars in the region of each cluster were determined applying the statistical method of Zhao e He [8] using the individual stellar UCAC2 (Zacharias et.al.[9]) proper motions. Consequently, the mean absolute proper motion of the clusters were also estimated. Using the investigated stars we were able to construct the colourmagnitude diagrams that allowed us to derive preliminary estimates of the fundamental parameters of the clusters such as reddening, distance and ages where the 2MASS (Strutskie et.al.[10]) photometric data were considered.
50

Identificação de matrizes de função de resposta em freqüência multidirecionais em estruturas complexas / Multidirectional frequency response functions matrices assessment in complex structures

Thiago Rodrigo Cicogna 24 October 2008 (has links)
Este trabalho apresenta o desenvolvimento de uma metodologia para a estimativa de funções de resposta em freqüência angulares (FRFAs). Trata-se de uma técnica que utiliza transdutores piezelétricos (PZT) do tipo bimorph para a medição da curvatura local da estrutura através do potencial elétrico induzido pela extensão e compressão do sensor. A partir da estimativa da curvatura, a rotação pode ser obtida diretamente através de várias técnicas de interpolação (polinomial, formas modais, etc). Apresenta-se a modelagem téorica da qual se deriva as equações que governam a dinâmica de estruturas uni-dimensionais, do tipo viga, e estruturas bidimensionais, do tipo placa, ambas isotrópicas, onde se incorpora o sensor bimorph. Modelos em elementos finitos foram propostos no intuito de avaliar a utilização destes sensores (bimorphs) aplicados à estimativa das FRFAs. Apresentam-se também resultados numéricos e experimentais considerando-se uma viga engastada-livre (cantilever) e resultados numéricos considerando-se uma placa simplesmente apoiada. Um algoritmo genético foi ainda desenvolvido no intuito de determinar a posição e dimensão ótimas dos bimorphs em estruturas do tipo viga. / The present work aims to perform the development of an attractive approach for accurate measurement of angular frequency response functions (AFRFs). It uses bimorph piezoceramic patches to measure the structure\'s local curvature through the measurement of the electric potential induced by the extension and compression of the patch\'s top and bottom stripes, respectively. From this curvature, rotation can be obtained directly by several interpolation techniques (single polynomial, modes basis). Theoretical modeling of the vibration incorporating piezoelectric bimorph sensor is presented and equations governing the dynamics for one-dimensional structures, like a beam, and for two-dimensional structures, like a plate, are derived for isotropic structures. Finite element model for the dynamic analysis were proposed to evaluate bimorphs patches applied to the measurement of angular FRFs. Numerical and experimental results are presented considering a cantilever beam and numerical results for a simply supported plate as tested structured. Also, in this work, a genetic algorithm was used as an adaptive heuristic search algorithm for optimal placement and sizing of the bimorph sensor into beam like structures.

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