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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.
81

Dynamically installed anchors for floating offshore structures

Richardson, Mark Damian January 2008 (has links)
The gradual depletion of shallow water hydrocarbon deposits has forced the offshore oil and gas industry to develop reserves in deeper waters. Dynamically installed anchors have been proposed as a cost-effective anchoring solution for floating offshore structures in deep water environments. The rocket or torpedo shaped anchor is released from a designated drop height above the seafloor and allowed to penetrate the seabed via the kinetic energy gained during free-fall and the anchor’s self weight. Dynamic anchors can be deployed in any water depth and the relatively simple fabrication and installation procedures provide a significant cost saving over conventional deepwater anchoring systems. Despite use in a number of offshore applications, information regarding the geotechnical performance of dynamically installed anchors is scarce. Consequently, this research has focused on establishing an extensive test database through the modelling of the dynamic anchor installation process in the geotechnical centrifuge. The tests were aimed at assessing the embedment depth and subsequent dynamic anchor holding capacity under various loading conditions. Analytical design tools, verified against the experimental database, were developed for the prediction of the embedment depth and holding capacity.
82

Numerical Analysis Of Large Size Horizontal Strip Anchors

Krishna, Y S R 07 1900 (has links)
Structures like transmission towers, tele-communication masts, dry-docks, tall chimneys, tunnels and burried pipelines under water etc are subjected to considerable uplift forces. The net effect of external loading on the foundations of these structures results in forces that try to pull the foundations out of the ground. Anchors are usually provided to resist such uplift forces. Earlier theoretical research of anchor behavior has focused on elastic response and ultimate pullout capacity. Many investigators have proposed techniques for determining the collapse load of anchors. Essentially the approaches involve the use of limit equilibrium concepts, with some assumptions regarding the shape of the failure surface and/or the influence of the soil above the anchor. The possible effect of dilatency and initial stress state are not considered in these methods. A number of investigators have used the results of small size model anchors to understand the behavior and extrapolated the results for predicting the behavior of large sized anchors. This has lead to unsatisfactory results. It has been clearly shown by Dickin (1989) that the failure displacements and load displacement curve patterns are very different for small and large sized anchors, i.e. they are not just proportional to the size of the anchor. Critical pullout load and the load displacement behavior are required for the complete analysis of anchor foundations. Though, many theories have been proposed to predict the uplift capacity within the limits of accuracy required at engineering level, at present no simple rational method is available for computing deformations. In the present investigation attempts have been made to analyze the load deformation behavior of large size strip anchors in sands, clays and layered soils using two-dimensional explicit finite difference program FLAG (Fast Lagrangian Analysis of Continua), well suited for geomaterials, by assuming soil to be a Mohr-Coulomb material in the case of sands and modified Cam-clay material in the case of clays. It is now well understood that the shearing resistance of a granular soil mass is derived from two factors frictional resistance and the dilatency of the soil. So the peak friction angle can be divided in to two components critical friction angle Фcv and dilation angle Ψ. Critical friction angle is the true friction angle as a result of frictional resistance at interparticle level when the soil is shearing at constant volume. If Фcv for a given soil remains constant, the value of Ψ has to increase with the increase in initial density of soil packing. The dilatency of a soil mass gradually decreases with continued shearing from its initial high value to zero after very large shear strains, when the soil finally reaches a constant, steady volume at critical states. Correspondingly the observed friction angle Ф reduces from its peak value to Фcv at a very large strain. In earlier days, clays used to be characterized by the strength parameters c and Ф. often, under undrained conditions, Ф would be even considered zero. But in the recent developments, it is understood that all the strength of clays is frictional. There is nothing like cohesion. The part of shear strength, which appears to be independent of normal stress, is shown to be the effect of over-consolidation and the resulting dilation. Thus although Cam-clay model uses zero cohesion for all clays, it reflects this component of strength through over-consolidation and in a more realistic way. Hence, it is appropriate to consider the pre-consolidation pressure as parameter in the analysis. More specifically, the various aspects covered in this investigation are as follows. Chapter 1 provides the general introduction. In chapter 2, the existing literature for the analysis of anchors for both experimental and analytical investigations on the pullout capacity of anchors in homogeneous and layered soils and the load deformation behavior of anchors under pullout are briefly reviewed. Chapter 3 deals with the features and the implementation of the two-dimensional explicit finite difference program, Fast Lagrangian Analysis of Continua (FLAC) and the constitutive modeling of soils. It discusses the background and implementation of Strain softening / hardening model. This model is based on the Mohr- Coulomb model with non-associated shear and associated tension flow rules. In this model the cohesion, friction, dilation and tensile strength may harden or soften after the onset of the plastic yield. Further the critical state concepts and implementation of the modified Cam-clay model have been discussed. Cam-clay model originally developed for clays reflects the hydrostatic pressure or density dependent hardening material response. Chapter 4 focuses on the analysis of load deformation behavior of large size anchors in granular soils. Two-dimensional explicit finite difference program (FLAC) is used for the simulations and the soil is modeled as a Mohr-Coulomb strain softening/hardening material In this chapter a series of simulations have been carried out on large size anchor plates, with parametric variation. By analyzing these results, a generalized load deformation relationship for different sizes of anchors and different types of soil have been proposed. The results are presented in the form of influence/design charts which can be used in hand calculations to obtain an estimate of anchor capacity and deformation for a wide range of soil types and size of anchors. Chapter 5 deals with the analysis of the drained and undrained behavior of large size horizontal strip anchors in clays using modified Cam-clay model. Earlier investigators have studied the undrained behavior of anchor plates in clays, but no studies are reported in literature for the drained behavior of anchors in clays. Further it is not clear whether, drained or undrained condition will be critical for an anchor. In this chapter the drained and undrained behavior of large size anchor plates in both normally consolidated and over-consolidated states have been made. It has been found that the undrained pullout capacity of an anchor in a soil of normally consolidated state will always be more than the drained capacity. This is contrast to the usual understanding that undrained behavior is more critical than the drained behavior. In Chapter 6 an attempt has been made to analyze the behavior of large size anchors in two layered sands and in conditions where backfill material has a higher or lower strength than the native soil, for different shape of excavations. Soil is assumed to be a Mohr-coulomb strain softening/hardening material. In Chapter 7 the entire investigation covered in earlier chapters has been synthesized and some specific conclusions have been highlighted.
83

Experimental in-plane behavior of a generic scale model drag embedment anchor in Kaolinite test beds

McCarthy, Katelyn Barbara 07 July 2011 (has links)
The trajectory and capacity are key components of the design of drag embedment anchor and drag-in vertically loaded anchors. This experimental testing program quantifies two factors that describe the anchor trajectory and capacity: the equilibrium bearing factor (Ne) and the tangential bearing factor (Ne). These factors can aid in the development of a numerical model of anchor behavior. A magnetometer device is used to track the orientation and location of the anchor during drag embedment. The results of the experimental testing program were compared with the results from a predictive model. The experimental program consisted of drag embedment tests with various testing conditions including different anchor line diameters and different initial pitch orientations. The results with the different anchor lines indicated that thinner anchor lines cause the anchor to dive deeper in the soil. The different initial pitch results indicate that regardless of the initial pitch of the anchor, the anchor rotates to a unique pitch trajectory within 2 fluke lengths. / text
84

Numerical Methods in Offshore Geotechnics: Applications to Submarine Landslides and Anchor Plates

Nouri, Hamid Reza 03 October 2013 (has links)
The emphasis of this dissertation is on using numerical and plasticity based methods to study two main areas of offshore geotechnics. The first part of this dissertation focuses on the undrained behavior of deeply embedded anchor plates under combined shear and torsion. Plate anchors are increasingly being used instead of typical foundation systems to anchor offshore floating platforms to sustain uplift operating forces. However extreme loading cases would create general loading conditions involving six degrees of freedom. The focus of my research was to evaluate the bearing capacity of plate anchors under two-way horizontal and torsional loading and to study the decreasing effect of torsional moment on the horizontal bearing capacity of these foundations. The study takes advantage of several approaches: Numerical simulation (two and three dimensional finite element analysis) Evaluating and modification of the available plasticity solutions Developing equations for three degree-of-freedom yield locus surfaces The same methodology is applied to evaluate the response of shallow foundations for subsea infrastructure subjected to significant eccentric horizontal loads. The second part of this study focuses on offshore geohazards. Coastal communities and the offshore industry can be impacted directly by geohazards, such as submarine slope failures, or by tsunamis generated by the failed mass movements. This study aims at evaluating the triggering mechanisms of submarine landslide under cyclic wave and earthquake loading. A simple effective stress elasto-plastic model with a minimal number of parameters accounting for monotonic and cyclic response of fine-grained material is developed. The new constitutive soil model could be used to simulate case histories and conduct parametric study to evaluate the effect of slope inclination angle, the earthquake loading with different PGA, frequency content, and duration, as well as various deposition rates to simulate different over pressure levels. This study will generate more insight on the static and cyclic behavior of submarine slopes and influencing factors on their triggering mechanisms using more comprehensive and realistic modeling tools. Several objectives are defined: Developing an appropriate constitutive formulation, Evaluating the constitutive model and material parameters for available databases.
85

Motivational factors and Leadership preferences of the Millennial generation : Unlocking the potential of our future leaders

Lopez, Clara Ines, Grubbström, Emma January 2018 (has links)
A lot of effort is put into diversity by organizations today, but the diversity question mainly focuses on gender, ethnicity, cultural and beliefs (Robertson, et al., (2017), while one of the most daunting diversity challenges has been proven to be diversity between generations, which often goes overlooked and unaddressed. A new generation represent an increasing share of the work force and many of them are already today positioned in leading positions, aspiring for leadership positions or aiming to reach for management positions to be able to do difference. Organizations that understand how to successfully address generational conflict and leverage each generation’s strengths will be better able to keep employees motivated and productive amidst the social and economical changes.   This study aims to explore the leadership preferences and motivation factors for the Millennial Generation, in order to unlock their potential and be able to bridge this knowledge gap. The preferences were examined through a survey, targeting a study group of millennial knowledge workers with various backgrounds from different companies to be able to dismiss possible bias reflecting different cultures. The survey was performed by adopting items from the Multifactor Leadership Questionnaire (MLQ), based on Bass’ (1985) Transactional – Transformational leadership theory and the Career Orientation Inventory (COI) reflecting Schein’s (1985) theory about career anchors.   The survey was delivered through several channels and in the end a sample group of 105 Millennial knowledge workers were included in further analysis. An Explorative Factor Analysis (EFA) was conducted to determine the underlying structure among the variables in the analysis. Since this research is based on previous studies (Blom, 2010), the methodology is chosen as a confirmatory approach with Confirmatory Factor Analysis (CFA) to show how well the model fits the data. A Structural Equation Modelling (SEM) is performed to evaluate the relationship between the variables from Leadership Questionnaire (MLQ) for Transactional and Transformation Leadership theory and Career Orientation Inventory for Career anchors.   Findings by Blom, (2010) reveal that the Millennial knowledge workers prefer leadership dimensions that involve intellectual stimulation and charisma, which correspond to a transformational leadership style compared to a transactional leadership style. This type of leadership focus on the change in individuals and creates valuable and positive changes, which inspires towards both common and individual goals. Similar results were obtained in our study and the relation with motivating factors shows that the sample group with higly educated people in the knowledge sector are motivated by having meaningful purpose with their job. They also wish to reach administrative positions in their companies and are interested by the thought of create and manage their own business. The interrelation between these factors determines the degree of satisfaction which is directly linked to the relationship between motivation and productivity. This is why it shall be one of the highest priorities of each organisation to find how to motivate their employees on an individual level, it is directly connected to productivity. Key words: Millennials, Transformational Leadership, Transactional Leadership, Career Anchors, knowledge workers
86

Utvärdering av trackingsystemen i ARKit och ARCore : En experimentell studie / Evaluation of the tracking systems in ARKit and ARCore : An experimental study

Halje, Gustav, Mansfeld, Pontus January 2018 (has links)
Syfte – För att konstruera lyckade mobila Augmented Reality-lösningar som får virtuella objekt att se ut att samexistera med verkligheten krävs robusta trackingsystem som klarar av att spåra position och orientering med hög precision. Således var studiens syfte att undersöka precisionen i trackingsystemen i ARKit och ARCore för att erhålla underlag om hur väl virtuella objekt kan förankras på en fysisk position. Både ARKit och ARCore använder konceptet förankringspunkter för att uppnå ökad precision i trackingen av virtuella objekt. Därav undersöktes hur pålitliga dessa förankringspunkter är för respektive ramverk och huruvida de förbättrar precisionen eller inte. Metod – I studien genomfördes egenutformade experiment där en app för respektive ramverk skapades med uppgiften att placera ut ett virtuellt objekt med eller utan förankringspunkt framför enheten. Med hjälp av fasta fysiska positioner som användes som referenspunkter kunde förskjutningar av virtuella objekt beräknas när enheten förflyttades i två olika scener. Resultat – Medelförskjutningen av förankringspunkterna i ARKit var 15,2 cm och 27 cm i respektive scen. För ARCore blev medelförskjutningen av förankringspunkterna 7,8 cm och 4,7 cm. Trackingen av virtuella objekt förbättrades i ARCore i båda scenerna när förankringspunkter användes. Däremot fick ARKit blandade resultat där trackingen förbättrades avsevärt när tillräckligt med textur fanns, men försämrades när det inte fanns. Implikationer – Studien visar att ARCore klarar trackingen av virtuella objekt bättre än ARKit. Vidare bekräftar studien att förankringspunkter bör användas för att förbättra precisionen i trackingen i ARCore, medan det i ARKit endast förbättras när tillräckligt med textur finns i omgivningen. Begränsningar – Endast en smartphone för respektive ramverk användes i experimenten. Scenerna var statiska och experimenten genomfördes i så ljusa förhållanden som möjligt. Studien testade enbart en förankringspunkt och säger således inget om hur pålitligheten och precisionen förändras när multipla förankringspunkter används. / Purpose – To construct successful mobile Augmented Reality solutions that make virtual objects coexist with reality, robust tracking systems capable of tracking position and orientation with high precision is required. The study's purpose was therefore to investigate the precision of the tracking systems in ARKit and ARCore to receive material regarding how well virtual objects can be anchored on a physical position. Both ARKit and ARCore utilize a concept called anchors to achieve heightened precision in the tracking of virtual objects. How reliable these anchors are in each framework and whether they improve precision was thus examined. Method – Experiments were designed and performed in the study, where one app for each framework was created with the purpose of placing a virtual object with or without an anchor in front of the device. Fixed physical positions were used as references to calculate how much the virtual object were drifting when the device was moved around in two different scenes. Findings – The average drift of the anchors were 15,2 cm and 27 cm with ARKit in each scene. The anchors with ARCore had an average drift of 7,8 cm and 4,7 cm. The study found that the tracking of virtual objects improved in ARCore when anchors were used, while ARKit gave mixed results where clear improvements could be seen only when there was enough texture in the scene. Implications – The study shows that ARCore handles the tracking of virtual objects better than ARKit. The study also confirms that anchors should be utilized to improve the precision of the tracking in ARCore, while in ARKit it is only improved when there are a sufficient amount of texture in the surroundings. Limitations – Only one smartphone for each framework were used in the experiments. The scenes were static and the experiments were performed in as bright conditions as possible. The study only tested one anchor and says nothing regarding changes in the reliability and precision when multiple anchors are used.
87

Exploring the relationship between career anchors, job satisfaction and organisational committment

Lumley, Elizabeth Jean 11 1900 (has links)
The primary objective of the study was to explore the relationship between career anchors, job satisfaction and organisational commitment using a sample of 86 employees at four Information Technology companies in South Africa. A secondary objective was to determine whether individuals from various gender, race, position and age groups differed significantly regarding their career anchors, job satisfaction and organisational commitment. The instruments used were the Career Orientations Inventory (COI), Job Satisfaction Survey (JSS) and Organisational Commitment Questionnaire (OCQ). The research findings indicated that career anchors are partially related to participants’ job satisfaction and organisational commitment and participants’ levels of job satisfaction and organisational commitment are significantly related. The findings also showed that demographic groups differ significantly regarding their career anchors, job satisfaction and organisational commitment. It is recommended that interventions aimed at improving individual career decision making and organisational retention practices take cognisance of how these variables relate to individuals’ career anchors, job satisfaction and organisational commitment. The study is concluded with recommendations for Industrial and Organisational Psychology practices and further research.
88

Ancoragem em rocha : avaliação da adesão entre nata de cimento e rochas sedimentares em ensaios de laboratório / Anchoring in rock: evaluation of bond strength between cement grout and sedimentary rocks by laboratory tests

Azevedo, Maurício Birkan January 2018 (has links)
A presente dissertação versa sobre a determinação do parâmetro de adesão entre nata de cimento e rocha. Este parâmetro é de fundamental importância no dimensionamento de grampos e tirantes ancorados, sistemas de contenção frequentemente executados que utilizam da técnica de ancoragem. Ensaios de arrancamento in loco são comumente realizados para avaliar essa tensão de aderência, no entanto, muitas vezes, apenas se tornam viáveis financeiramente durante a etapa de execução das obras. A metodologia Composite Cylinder Bond Test (CCBT) permite a determinação da adesão de maneira mais simples e com menor custo, por meio de ensaios de laboratório utilizando corpos de prova mistos de rocha e nata de cimento, sendo, por isto, uma interessante alternativa para a etapa de definição paramétrica de projetos. Neste contexto, foram estudadas três litologias sedimentares do município de Caçapava do Sul/RS – aqui chamadas de conglomerado, arenito muito fino e arenito médio – pertencentes à Formação Varzinha. A caracterização dessas litologias foi realizada por meio de lâminas delgadas e outros ensaios de caracterização de laboratório A classificação textural do conglomerado é de conglomerado arenoso, o arenito muito fino é classificado como arenito lamoso e o arenito médio é classificado como arenito. Do ponto de vista composicional, o arenito muito fino é classificado como arcóseo, enquanto o arenito médio é classificado como arcóseo lítico. Noventa ensaios CCBT, além de ensaios de resistência à compressão simples das rochas e da nata de cimento foram realizados. As tensões de adesão médias obtidas dos ensaios de laboratório foram de 2,52 MPa para o conglomerado, 1,84 MPa para o arenito muito fino e 1,43 MPa para o arenito médio. Foi realizada uma avaliação de intervalos de confiança de valores de tensão de adesão, conforme a distribuição t-student. Concluiu-se que não apenas a resistência das rochas influencia nessa capacidade de adesão, mas também a capacidade de absorção d’água e a porosidade. Maiores valores dessas duas propriedades na rocha favorecem a adesão entre os dois materiais. Os valores encontrados em laboratório são compatíveis com dados de literatura de campo em rochas similares. / This dissertation evaluates the determination of the adhesion parameter between cement grout and rock. This parameter is of great importance on design of two systems frequently executed that use the technique of anchoring: rock anchors and bolts. Pull out field tests are commonly carried out to evaluate this bond strength, however, they are normally only economically feasible during the construction stage. The Composite Cylinder Bond Test (CCBT) methodology allows the adhesion determination in a simpler and cheaper way, by laboratory tests using mixed samples of rock and cement grout. Therefore, the CCBT is an interesting alternative to project definition of adhesion values. In this context, three different sedimentary lithologies from Caçapava do Sul/RS, Southern Brazil, were studied. The lithologies – called here as conglomerate, fine sandstone and medium sandstone – belong to Varzinha Formation. The characterization of these lithologies were made by thin sections and characterization laboratory tests The textural classification of the conglomerate was sandy conglomerate, the fine sandstone was classified as muddy sandstone, and the medium sandstone was classified as sandstone. In the view of their composition, the fine sandstone was classified as arkose, while the medium sandstone was classified as lithic arkose. Ninety CCBT tests, besides unconfined compression tests on rock and cement grout specimens were carried out. The average adhesion values obtained from laboratory tests were 2,52 MPa for the conglomerate, 1,84 MPa for the fine sandstone and 1,43 MPa for the medium sandstone. An evaluation of confidence intervals of adhesion was also carried out, according to t-student distribution. It was concluded that the adhesion strength was influenced not only by the unconfined compressive strength of the rocks, but also by their water absorption and porosity. Larger values of these two properties increased the adhesion between the two materials. The values obtained from laboratory tests are compatible with literature field data in similar rocks.
89

Consolos instalados em etapa posterior à concretagem de pilar com auxílio de adesivo químico / Post-installed corbels with adhesive anchor

Damasceno, João Henrique Lannes 29 February 2016 (has links)
Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-10-07T11:31:11Z No. of bitstreams: 1 DissJHLD.pdf: 3895353 bytes, checksum: 53c29aff0accbd5c314333ed3809d578 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T13:47:49Z (GMT) No. of bitstreams: 1 DissJHLD.pdf: 3895353 bytes, checksum: 53c29aff0accbd5c314333ed3809d578 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T13:47:58Z (GMT) No. of bitstreams: 1 DissJHLD.pdf: 3895353 bytes, checksum: 53c29aff0accbd5c314333ed3809d578 (MD5) / Made available in DSpace on 2016-10-20T13:48:07Z (GMT). No. of bitstreams: 1 DissJHLD.pdf: 3895353 bytes, checksum: 53c29aff0accbd5c314333ed3809d578 (MD5) Previous issue date: 2016-02-29 / Não recebi financiamento / One of the most important principles in the connections design is the continuous search for simple solutions. Maximum economy in the precast construction is achieved with simple connection elements, with adequate performance and quick installation. One of the alternatives to be considered during the project to improve the simplicity in the column production is to avoid holes and cuts in the formwork. Projections and holes in the forms are laborious and reduce its lifecycle. Then, in order to make the column production process easier, this work aims study the alternative of using chemical adhesive for fastening the corbel reinforcement after casting the column. The work presents a literature review about the main concepts that are important to this solution: Connections design, chemical anchors, corbels and strut and tie models. The research also contains an experimental program with 3 tests full scale specimens with equal dimensions short corbels. Were tested 2 postinstalled corbels with the main tie reinforcement fastened with adhesive anchor and 1 cast in corbel with the main tie reinforcement anchored with hooked 90 º bars. The cast in corbel (specimen A) was designed according to the recommendations of the standards NBR6118:2014 e NBR9062:2006, 1 post-installed corbel (specimen B) was designed with the same anchorage length of the cast in corbel and the other post-installed corbel was designed according to the recommendations of the chemical adhesive producer. This way, was possible evaluate the influence of the anchorage length in the corbel behavior and the safety of the solution comparing with a cast in corbel. The anchorage length did not influence the corbel behavior during the test. The specimen A presented the ultimate load of 400 kN, specimen B 340 kN and specimen C 377 kN. All of the specimens presented failure by flexure-tension in a ductile manner and ultimate loads higher than foreseen by standards and calculation models. The post-installed specimens (B and C) had a similar behavior, presented higher crack width and were less stiffer than the specimen A. Specimens B and C also presented an inclined crack in the anchorage region of the column that alert to a different stress distribution in the anchorage region. Thus the solution of post-installed corbels with adhesive anchors presented a satisfactory performance, further research is needed in order to reduce the crack widths in the corbel region and avoid the cracks in the column. / Um dos princípios mais importantes no projeto de ligações é a busca contínua por soluções simples. A máxima economia em uma construção pré-moldada é atingida quando os elementos de ligação são razoavelmente simples, com um desempenho adequado e com uma montagem rápida. Uma das alternativas a ser considerada durante o projeto, visando melhorar a simplicidade na produção de pilares, é evitar furos e saliências nas fôrmas. Projeções que requerem furações e recortes nas fôrmas são trabalhosas e reduzem sua vida útil. Assim, com o intuito de facilitar o processo produtivo de pilares com consolos, o presente trabalho visa estudar a alternativa de utilizar adesivos químicos para a instalação das barras que compõe a armadura e concretagem do consolo em etapa posterior à execução do pilar. O trabalho apresenta uma revisão bibliográfica acerca dos principais conceitos que são importantes para esta solução: comportamento de ligações, ancoragens químicas, consolos e modelos de bielas e tirantes. A pesquisa também traz um programa experimental no qual foram ensaiados três modelos em escala real com consolo curto de mesmas dimensões, dois consolos com armadura do tirante ancorada com ancoragem química e um consolo monolítico com armadura ancorada com gancho dobrado a 90º. O consolo monolítico (modelo A) foi projetado atendendo os requisitos das normas NBR 6118:2014 e NBR 9062:2006. Um modelo (modelo B) com ancoragem química foi projetado com o mesmo comprimento de ancoragem do modelo monolítico e outro modelo (modelo C) com ancoragem química foi projetado conforme as recomendações do fabricante do adesivo químico. Desta forma, foi possível avaliar, através da comparação entre os modelos, a influência no comportamento do comprimento de ancoragem e a segurança desta solução em comparação com um consolo monolítico. O comprimento de ancoragem não apresentou influência no comportamento dos consolos pós-instalados. O modelo A apresentou carga última de 400 kN, o modelo B de 340 kN e o modelo C de 377 kN. Todos os modelos apresentaram ruptura por tração na flexão de forma dúctil e cargas últimas maiores que o previsto por normas e modelos de cálculo Os modelos com ancoragem química (B e C) tiveram comportamento similar, apresentaram maior abertura de fissuras e menor rigidez em comparação com o modelo monolítico. Os modelos B e C também apresentaram uma fissura inclinada no pilar na região da ancoragem, que atenta para uma distribuição de tensões diferente na região da ancoragem. A alternativa de consolos com ancoragens químicas mostrou comportamento satisfatório, no entanto, a solução ainda necessita de maiores estudos, principalmente no sentido de se reduzir a abertura de fissuras no consolo e combater o aparecimento de fissuras no pilar.
90

Integração de mapas genéticos / Integrated genetic maps

Salgado, Caio Césio 28 July 2008 (has links)
Made available in DSpace on 2015-03-26T13:42:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1107978 bytes, checksum: 5a845c5ae4a67c50d70037eeeeb7eed9 (MD5) Previous issue date: 2008-07-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The genetic mapping facilitates the breeding work once one or more marks of the genotype can be associated to controlling genes of qualitative and quantitative characteristics (QTL). Genetic maps for several species have been built by different groups of researchers with different molecular markers and populations. A way to generate maps more saturated for those species would be the integration of the existent maps. The key to integrate different maps is the presence of common marks among them. Only when there are a minimum number of common marks among the different maps, these can be integrated. This way, the objective of this work was to develop a process of integration of genetic maps and to test the efficiency of this process. Data from the simulation of genome and populations were generated and analyzed. A important factor to obtain solid data in a mapping work is the sample or population size. Based in these simulated data it was evaluated the optimum population size to study the integration of genetic maps. To obtain and study the consensus maps, parental genomes and samples of co- dominant F2, dominant F2 and backcrosses populations were simulated. The generated samples had 100, 200, 400 individuals with 3 linkage groups each and 11 dominant and co-dominant molecular marks spaced by 5, 10 and 15 centiMorgans. 10 repetitions were accomplished by sample, five used to construct the consensus maps with analysis multilocus and other five without analysis multilocus. It was concluded that the obtention of the consensus maps becomes more efficient with the increase of the population size. A population size of 200 individuals would be enough to rescue the original information. To study the obtention of the effective integrated map samples of co-dominant F2 and backcrosses populations were simulated. The generated samples had 100, 200 and 400 individuals, 21 marks for linkage group and markers equidistant by 5 cM, in a total of four simulations for co-dominant F2 and four for backcrosses. Each simulated genome was fragmented in four new maps which three maps had eight markers and one had nine markers, each one of these maps containing four markers that are anchors among the four maps. These new maps were aligned, orderly and integrated and then compared with the original map. It was concluded that the process of ordainment and integration are efficient to obtain the integrated map. The population size exercises influence on the map and the distances measures among the marks. / O mapeamento genético facilita o trabalho de melhoramento uma vez que uma ou mais marcas do genótipo podem ser associadas a genes controladores de características qualitativas e quantitativas (QTL). Mapas genéticos para diversas espécies tem sido construídos por diferentes grupos de pesquisadores com diferentes tipos de marcadores e diferentes tipos de populações. Uma maneira de gerar mapas mais saturados para as diversas culturas seria a integração dos mapas genéticos já existentes. A chave para integração de mapas distintos é a presença de marcas comuns entre os mapas. Somente quando há um número mínimo de marcas comuns entre os diferentes mapas, estes podem ser integrados. Deste modo, o objetivo deste trabalho foi desenvolver um processo de integração de mapas genéticos e testar a eficiência do processo de integração. Para isso foram gerados e analisados dados a partir da simulação de genoma e de populações. Um dos fatores de fundamental importância para se obter dados consistentes em um trabalho de mapeamento é o tamanho da amostra ou população a ser trabalhada. Com base nestes dados simulados, avaliou-se o tamanho ótimo de populações para estudo de integração de mapas genéticos. Para estudo e obtenção dos mapas consenso foram simulados genomas parentais e amostras de populações F2 codominantes, F2 dominantes e de retrocruzamentos. As amostras geradas foram de tamanho 100, 200 e 400 indivíduos com três grupos de ligação cada e 11 marcas moleculares co-dominantes e dominantes espaçadas a 5, 10 e 15 centimorgans por grupo de ligação. Foram realizadas 10 repetições por amostra, sendo que destas, cinco foram utilizadas para construção de mapas consenso com análise multiloco e outras cinco sem análise multiloco. Concluiu-se que a obtenção dos mapas consenso se torna mais eficiente com aumento do tamanho da população. Um tamanho populacional de 200 indivíduos seria o suficiente para resgatar as informações originais. Para estudo da obtenção do mapa integrado efetivo foram simuladas F2 co-dominante e retrocruzamento com tamanhos de 100, 200 e 400 indivíduos, com 21 marcas por grupo de ligação e marcadores eqüidistantes a 5 cM, em um total de quatro simulações para F2 codominante e quatro para retrocruzamentos. Cada genoma simulado foi fragmentado em quatro novos mapas de modo que, foram obtidos três mapas com oito marcadores e um com nove marcadores, sendo que cada um deles constando quatro marcadores que são âncoras entre os quatro mapas. Estes novos mapas foram alinhados, ordenados, integrados e em seguida comparados com o mapa de origem. Concluiu-se que os processos de ordenamento e integração são eficientes para obtenção do mapa integrado e, também, que o tamanho da população exerce influência sobre o mapa e as medidas de distâncias entre as marcas.

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