• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 273
  • 85
  • 43
  • 42
  • 34
  • 13
  • 8
  • 8
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 622
  • 109
  • 98
  • 63
  • 52
  • 51
  • 47
  • 46
  • 45
  • 43
  • 41
  • 40
  • 39
  • 39
  • 37
  • 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.
221

Strike-slip faulting, breccia formation and porphyry Cu-Au mineralization in the Gunung Bijih (Ertsberg) mining district, Irian Jaya, Indonesia /

Sapiie, Benyamin, January 1998 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Four folded plates in pocket. Includes bibliographical references (leaves 285-303). Available also in a digital version from Dissertation Abstracts.
222

Tectonics and basin deformation in the Cabot Strait Area and implications for the late Paleozoic development of the Appalacians in the St. Lawrence Promontory /

Langdon, George S., January 1996 (has links)
Thesis (Ph.D.)--Memorial University of Newfoundland, 1996. / Restricted until November 1997. Bibliography: leaves 228-255. Also available online.
223

Influence of Hydrodynamic Slip on the Wake Dynamics and Convective Transport in Flow Past a Circular Cylinder

Nidhil Mohamed, A R January 2017 (has links) (PDF)
Hydrodynamic slip is known to suppress vorticity production at the solid-fluid boundary in bluff body flows. This suppression combined with the enhanced vorticity convection results in a substantial reduction in the unsteady vortex shedding and the hydrodynamic loads experienced by the bluff body. Here, using combined theoretical and computational techniques, we investigate the effect of slip on three-dimensional wake dynamics and convective scalar transport from a circular cylinder placed in the uniform cross-flow of a Newtonian incompressible fluid over Reynolds numbers ranging from 0.1 to 1000. We find the wake patterns to be strongly influenced by the degree of the slip, quantified through the non-dimensional slip length in the Naiver slip model, with the asymptotic slip lengths of zero and infinity characterizing no-slip and no-shear boundaries, respectively. With increasing slip length, the wake three-dimensionality, that is observed in the case of a no-slip surface for Re > 190, is gradually suppressed and eventually eliminated completely. For each Reynolds number, we identify the critical slip length beyond which the three-dimensionality is completely suppressed and the wake becomes two-dimensional, on the basis of the total transverse entropy present in the flow field. Over the Reynolds number range considered in this work, we find the critical slip length to be an increasing function of Reynolds number. For sufficiently large slip lengths, we observe suppression of two-dimensional vortex shedding leading to formation of a steady separated wake. Further increments in slip length lead to reduction in the intensity and size of the recirculating eddy pair eventually resulting in its complete disappearance for a no-shear surface for which the flow remains attached all along the cylinder boundary. Next, we quantify the effect of hydrodynamic slip on convective transport from an isothermal circular cylinder placed in the uniform cross flow of an incompressible fluid at a lower temperature. For low Reynolds and high P´eclet numbers, theoretical analysis based on Oseen and thermal boundary layer equations allows us to obtain explicit relationships for the dependence of transport rate on the prescribed slip length. We observe that the non-dimensional transport coefficients follow a power law scaling with respect to the P´eclet number, with the scaling exponent increasing gradually from the lower asymptotic limit of 1/3 for the no-slip surface to 1/2 for a no-shear boundary. Results from our simulations at finite Reynolds number indicate that the local time-averaged transport rates for a no-shear surface exceed the one for the no-slip surface all along the cylinder except in the neighbourhood of the rear stagnation region, where flow separation and reversal augment the transport rates substantially.
224

Manufacture and characterisation of carbon fibre prepreg stacks containing resin rich and resin starved slip layers

Toure, Saran Mariam January 2015 (has links)
The cost of manufacturing high quality composite components can be significantly reduced by using Out of Autoclave (OOA) processes if they can achieve final parts with a finish quality as high as that obtained using an autoclave process. Much research has been carried out recognising that regardless of the reinforcement fibre orientation, manufacturing of preimpregnated (prepregs) carbon components is much affected during its forming stage by fibre deformation and failure modes. This work sought to reduce wrinkling in the moulding of prepregs by introducing slip layers within the lay-up. Three types of slip layers were used: a dry fabric, a resin rich layer and a resin film. In order for the slip layers to be fully incorporated into the final laminate the resin content within the slip layer must be adjusted prior to crosslinking. In the case of dry fabric layer, additional resin must be introduced and in the case of a resin rich layer and resin film layer, excess resin has to be removed. The laminates used in the project were based on 2/2 twill and unidirectional carbon prepregs. These were manufactured by either Resin Infusion (RI) or Vacuum Bagging (VB). Resin adjustments were made at the same time. The 2/2 twill and unidirectional carbon prepregs were first characterised by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Thermal Analysis (DMTA) before RI and VB. Dry 2/2 twill and unidirectional carbon fabrics and/or Resin Film (for VB) or fabrics and Epoxy Resin (for RI) were introduced in several plybooks and then cured. Final parts were either made of 2/2 twill carbon or unidirectional carbon. The parts were used to investigate the relationship between individual plies during the consolidation of a plybook. The first characterisations were done on flat laminates. Also two moulds were manufactured and used to produce new parts for further characterisations. The first, an aluminium mould was machined using a Computer Numerical Control (CNC). The second mould was a fan blade, made using chopped strand mats. The final parts had 3, 4 or 6 plies. These parts were characterised using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Torsion testing. The results provide a first step towards understanding how the friction at a ply/ply level can be influenced by the "starving" or the "enriching" of resin in a plybook during its consolidation. The work showed that in OOA manufacturing, the friction at a ply/ply level can be controlled by introducing Resin Film, Dry or Resin Rich Fabrics in a prepreg plybook. It was demonstrated that introducing lubrication to control ply friction during forming can result in quality part as high as that obtained from a traditional composite forming process. As the final parts were made using a fixed die mould and a vacuum bag, most of the plies in the layups could deform individually and accommodate interply shear. Torsion testing on a number of a random selection of samples showed negligible effects on shear stresses, strengths and modulus within the parts were negligible. It is argued that the flexibility of the vacuum bag could have had an impact on the layups during forming. The plies could conform to the mould easier. This work has potential for other applications. For example in match die moulding, introducing wet lubrication could improve interply shear during forming and help in improving accuracy and geometrical conformity of final parts. Furthermore, developing techniques to control friction during forming in OOA can be attractive to industries which could not afford to invest in this OOA prepreg technology. OOA processing times have become very attractive to industries such as the sporting good, automotive, wind energy and transportation. These industries could explore the opportunity presented by the work in this EngD thesis.
225

Glissements sismiques et asismiques : le cas du Japon / Seismic and aseismic slip : the Japanese subduction zone

Gardonio, Blandine 02 March 2017 (has links)
L'existence de glissements lents a été observé pour la première fois en Californie, sur une portion de la faille de San Andreas (Steinbrugge et al., 1960,Tocher 1960). Ils ont ensuite été détéctés dans les années 90s avec l'avènement des GPS. Les interactions entre glissement lents, ou glissements asismiques (qui n'émettent pas d'ondes élastiques) et les glissements sismiques est cependant mal connue.Pourtant, cette question est fondamentale puisque des glissements lents ont été observés avant plusieurs séismes.Par exemple, l’installation d’un glissement lent avant le séisme d’Izmit de 1999 en Turquie a été mise en évidence grâce à l’analyse de signaux répétitifs (Bouchon et al., 2011). De même, en étudiant le comportement des séismes répétitifs avant le méga-séisme de Tohoku de 2011, deux séquences de glissement lent en direction du point d’initiation ont été observées (Kato et al., 2012). D’autres glissements lents précédents des séismes de grandes ampleurs ont été reportés, notamment au Mexique, avant le séisme de Papanoa (Radiguet et al., 2016) de magnitude 7.3 et au Chili, avant le séisme d’Iquique de 2014 de magnitude 8.2 (Ruiz et al., 2014).L'objectif de ce travail de thèse est de mieux caractériser les interactions qui existent entre glissements sismiques et asismiques dans une zone de subduction très largement instrumentée: le Japon.La très grande densité des réseaux Japonais (sismique courte et longue période, GPS) autorise des seuils de détection des glissements sismiques ou lents très bas, et permet d'utiliser des méthodes de réseaux afin de maximiser le rapport signal sur bruit. La recherche d'épisodes de déformation lente est basée sur plusieurs types d'observables et de méthodes, et est complétée par l'analyse des changements de taux de sismicité accompagnant ces épisodes. Cette thèse vise ainsi à mieux comprendre comment du glissement lent peut -ou non- accélérer l'occurrence de grands séismes, et les conditions requises pour se faire. / Transient aseismic slip events (that do not emit elastic waves) were first discovered on the San Andreas fault in central California in 1960 (Steinbrugge et al., 1960, Tocher 1960) and were later confirmed by the development and installation of GPS stations. Aseismic slip can occur on continental faults as well as on subduction zones. However, the interactions between aseismic and seismic slips are not fully captured yet. Understanding the mechanisms at stake on fault planes is fundamental since several large earthquakes were preceded by aseismic slip episodes.For example, the setting of a slow slip event before the 1999 Izmit earthquake in Turkey was evidenced by the observation of repeating signals at one station (Bouchon et al., 2011). Also, by studying repeating earthquakes before the 2011 Tohoku earthquake, two slow slip episodes that migrated towards the rupture intitiation were observed (Kato et al., 2012). Other transient slips preceding large earthquakes occurred, including in Mexico, before the M7.3 Papanoa earthquake (Radiguet et al., 2016) and in Chile, before the 2014 Iquique earthquake (Ruiz et al., 2014).The aim of this thesis is to better characterize the interactions between seismic and aseismic slip that can occur in a subduction zone largely instrumented: Japan.The very high density of the japanese monitoring networks(seismic networks, both at short and long periods, and GPS network), allows the detection ofseismic and aseismic slip events with low intensity / size, and is amenable to the use of arraymethods to improve the signal-to-noise ratio. The search for episodes of transient deformation will be based on several observables andtechniques, and is complemented by the analysis of the changes in earthquake rates concomittent to these episodes. This work thus gives new clues on how aseismic deformation can -or not- accelerate the occurrence of strong earthquakes, and on what are the conditions (tectonic, dynamic) for this to happen.
226

Enhanced mass transport in graphene nanofluidic channels

Xie, Quan 20 February 2018 (has links)
Enhanced mass transport in carbon-based nanoscale conduits (e.g. carbon nanotubes, graphene nanochannels/capillaries, graphene/graphene oxide membranes) has attracted tremendous interest over the last decade due to its significant implications for water desalination/purification, nanofiltration, electronic cooling, battery/fuel cells, and lab-on-a-chip. Further development of carbon-based nanoscale conduits for practical applications relies on understanding fundamental mechanisms of transport through individual conduits, which have not been well studied due to challenges in fabrication and measurement. In this thesis, the construction of two-dimensional planar graphene nanochannel devices and the studies of enhanced water and ion transport inside the graphene nanochannels are reported for the first time. The graphene nanochannels are fabricated by conformally covering high-quality graphene on the surfaces of silica nanochannels. A new fabrication scheme consisting of graphene wet transfer, graphene patterning and vacuum anodic bonding is developed to create such graphene nanochannels with heights ranging from 24 to 124 nm. Using these nanochannels and a new hybrid nanochannel based capillary flow measurement technique, we successfully measured the hydraulic resistance (water permeability) of single graphene nanochannels. Our results demonstrate that the frictionless surface of graphene induces a boundary slip and enhances water flow inside the graphene nanochannel. The measured slip length of graphene in the graphene nanochannels poses a median value around 16 nm, albeit with a large variation from 0 to 200 nm regardless of the channel height. The small-yet-widely-varying values of the graphene slip length are attributed to the surface charge of graphene and the interaction between graphene and underneath silica substrate, which are in good agreement with the prediction of our molecular dynamics (MD) simulation. In addition, we also investigated enhanced ion transport inside the graphene nanochannels. Higher electroosmotic conductance at low electrolyte concentrations (10-6 M~10-2 M) is observed in graphene nanochannels when compared with silica nanochannels with the same geometry. Our results suggest that the enhanced electroosmotic flow is also due to the boundary slip at the graphene/electrolyte interface. Besides, our analysis shows that the surface charge on the graphene, originating from the dissociation of oxygen-containing functional groups, is crucial to the enhanced electroosmotic flow inside nanochannels.
227

Design, implementation and evaluation of a model for Service-learning in Pharmacy (SLIP) at a tertiary hospital

Parker, Miriam Bibi January 2009 (has links)
Magister Pharmaceuticae - MPharm / In recent years the focus of pharmacy practice has changed from being primarily 'drug-centred to' one which is 'patient-centred' (El-Awady et al., 2006, p. l ). Developments in pharmacy curricula worldwide are reflecting this change. Pharmacy courses no longer concentrate primarily on theoretical content, but increasingly on the ability of students to apply their theoretical knowledge in practice. The South African Pharmacy Council (SAPC) requires that pharmacy education and training in South Africa equips pharmacists for the roles they will take on in practice. In order to accomplish this, the SAPC has prescribed competency unit standards for entry level pharmacists which may serve as a guide for pharmacy educators. A significant challenge in pharmacy education is the application of theory in practice settings (Bucciarelli et al., 2007), which possibly affects the ability of entry-level pharmacists to meet the SAPC unit standard competencies. The dire shortage of pharmacists in public sector health settings further emphasizes the need for a level of competency of entry level pharmacists so that they may enter the workplace ready to serve the medicine related needs of society. Service-learning is defined as experiential learning in which students engage in structured activities that address community needs and promote learning. The purpose of this study was to design, implement and evaluate a Service-learning in Pharmacy (SLIP) intervention which is intended to serve as a generic model which can be used in tertiary hospital pharmacies. The SLIP intervention aimed to promote student learning by providing opportunities for students to engage in structured activities, while simultaneously alleviating pharmacy workload.
228

Stratigraphic Record of Pliocene-Pleistocene Basin Evolution and Deformation Along the San Andreas Fault, Mecca Hills, California

McNabb, James 17 June 2014 (has links)
Sedimentary rocks in the Mecca Hills record a 3-4 Myr history of basin evolution and deformation within the southern San Andreas fault (SAF) zone. Detailed geologic mapping, measured sections, lithofacies analysis, and preliminary paleomagnetic data indicate that sedimentation and deformation in the Mecca Hills resulted from evolution of local fault zone complexities superimposed on regional subsidence and uplift. Sediment was derived from sources northeast of the SAF and transported southeast along the fault zone in large rivers, alluvial fans, and a smaller fault-bounded lake. Inversion of the Painted Canyon fault from oblique SW-side down to SW-side up slip was the main control on local deposition and deformation. Regional controls are suggested by an angular unconformity observed in the Mecca and Indio Hills along ~50 km of the SAF and synchronous post-740 ka uplift northeast of the SAF along ~80 km of the fault zone.
229

Uso de neuro-fuzzy na avaliação da suscetibilidade de escorregamento de taludes. / Use of neuro-fuzzy technique to indicate the susceptibility of landslide slopes.

Michelle Nogueira Guedes 20 December 2011 (has links)
A Presente dissertação apresenta uma aplicação de Inteligência Computacional na área de Geotecnia, com a utilização da Técnica de Neuro-Fuzzy para indicar a suscetibilidade de escorregamento de taludes no município do Rio de Janeiro, a partir de inspeção visual. Neste trabalho, a suscetibilidade corresponde à possibilidade de ocorrência de escorregamento sem considerar os danos relacionados ao evento. Adotou-se como variável de saída a Previsão de Escorregamento (PE) com três adjetivos que correspondem a Suscetibilidades Alta, Média e Baixa. A metodologia utilizada consistiu em, inicialmente, montar um banco de dados com informações preliminares de análise de estabilidade, com a indicação dos condicionantes de escorregamento relacionados à geomorfologia, pluviosidade, capacidade de drenagem, vegetação e ocupação com seus respectivos graus de suscetibilidades de escorregamento obtidos em um conjunto de Laudos de Vistoria da Geo Rio. O banco de dados foi aplicado em um algoritmo de Neuro-Fuzzy. Diversos testes foram realizados com as alterações dos parâmetros do modelo Neuro-Fuzzy para uma combinação de fatores condicionantes de escorregamento e refinamento do banco de dados. Os testes apresentaram diminuição do erro fornecido pelo programa com o aumento de tipos de condicionantes utilizados no treinamento, o que permite inferir que o escorregamento ocorre por uma complexa relação entre diversos fatores condicionantes. O banco de dados utilizado nos testes apresenta descontinuidades nas relações entre os diversos condicionantes, ou seja, para uma mesma faixa de valores de Altura do talude, não é possível obter uma relação para todas as faixas de outro condicionante e, até mesmo, para todas as faixas da Previsão de Escorregamento. As PEs obtidas na validação do modelo tiveram seus valores próximos aos desejados somente nos conjuntos de variáveis utilizadas para o treinamento. O modelo não foi capaz de apresentar valores de suscetibilidades dentro da faixa de valores utilizados no treinamento para combinação de variáveis com pequenos ruídos, o que indica a necessidade de ampliação do banco de dados tanto quantitativamente quanto qualitativamente de modo a cobrir as descontinuidades apresentadas nas relações entre as variáveis. / This paper is an application of Computational Intelligence in the Geotechnical Engineering, with the use of Neuro-Fuzzy Technique to indicate the susceptibility of landslide slopes in the city of Rio de Janeiro, from visual inspection. In this work, the susceptibility corresponds to the possibility of slipping without considering the damage related to the event. Adopted as the output variable Forecast Slip (PE Previsão de Escorregamento) with three adjectives that correspond to susceptibilities High, Medium and Low. The methodology used was to initially build a database with preliminary information for stability analysis, indicating the slip constraints related to geomorphology, rainfall, drainage capacity, vegetation, and occupation with their respective degrees of susceptibilities slip obtained on a set of the Reports of Condition Geo Rio. The database was implemented in a Neuro-Fuzzy algorithm. Several tests were conducted with the changes of model parameters Neuro-Fuzzy for a combination of conditioning factors of slipping and refinement of the database. The tests showed a decrease of the error provided by the program with increasing types of constraints used in the training, which allows us to infer that the slip occurs by a complex relationship between various conditioning factors. The database used in the tests discontinuities present in relations between the different conditions, ie, for the same range of height values of the slope, it is not possible to obtain a relationship for all the tracks of another condition, and even for all tracks from Forecast Slip. The PEs obtained in the validation of the model values were close to the desired only in sets of variables used for training. The model was not able to present values of susceptibilities in the range of values used in training for the combination of variables with small noise, which presents the need to expand the database so quantitatively and qualitatively in order to cover the discontinuities presented in relations between the variables.
230

Stanovení poloměru otáčení u traktorů Zetor Forterra 140 HSX, Zetor Proxima 120 Power a Zetor 7745 Turbo pro potřeby počítačových modelů

ZLOCH, Jan January 2018 (has links)
The main aim of this diploma thesis is to determine the radius of rotation of selected tractors (Zetor Forterra 140 HSX, Zetor Proxima 120 Power and Zetor 7745 Turbo) on three different types of surfaces using different speeds. The literary part deals briefly with the importance and historical development of tractors, the basic knowledge of traction theory, the problems of forces acting on the rolling wheel, and last but not least the construction of the tractor parts. The practical part is mainly focused on determining the radii of rotation of individual tractors on three specified types of surfaces using the three given speeds. The discussion is mainly focused on comparing the radii of rotation meeting ČSN 30 0552 with the radii given by the tractor manufacturer.

Page generated in 0.0248 seconds