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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.
261

Comparative Analysis of Marine Structural End Connections

Silewicz, Bret 20 December 2009 (has links)
Numerous structural end connections are utilized everyday in the marine industry for ship design and/or maintenance. End connection design has been developed in earlier vessel designs and adapted as a general standard for all vessels being designed / built at a facility. Usually the supporting calculations developed to analyze the structural end connection are not available for engineers to re-examine. Furthermore, young engineers employ un-proven end connections in their designs, using the justification “It has been done like this in the past, it should work.” In this thesis, the author concentrates on finite element analysis for thirteen typical end connections used in the marine industry and correlated the shear and moment transfer to an AISC developed empirical beam equation for comparison. The author will rely on first principle equations and finite element analysis to prove the efficiency of various end connections, and draw comparative conclusions per each end connection analyzed.
262

Consistent co-rotational formulations for geometrically non linear beam elements with special ref to large rotations

Cole, Garry January 1990 (has links)
No description available.
263

Finite volume approximation of the Maxwell's equations in nonhomogeneous media.

January 2000 (has links)
Chung Tsz Shun Eric. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 102-104). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Applications of Maxwell's equations --- p.1 / Chapter 1.2 --- Introduction to Maxwell's equations --- p.2 / Chapter 1.3 --- Historical outline of numerical methods --- p.4 / Chapter 1.4 --- A new approach --- p.5 / Chapter 2 --- Mathematical Backgrounds --- p.7 / Chapter 2.1 --- Sobolev spaces --- p.7 / Chapter 2.2 --- Tools from functional analysis --- p.8 / Chapter 3 --- Discretization of Vector Fields --- p.10 / Chapter 3.1 --- Domain triangulation --- p.10 / Chapter 3.2 --- Mesh dependent norms --- p.11 / Chapter 3.3 --- Discrete circulation operators --- p.13 / Chapter 3.4 --- Discrete flux operators --- p.20 / Chapter 4 --- Spatial Discretization of the Maxwell's Equations --- p.23 / Chapter 4.1 --- Derivation --- p.23 / Chapter 4.2 --- Consistency theory --- p.29 / Chapter 4.3 --- Convergence theory --- p.33 / Chapter 4.3.1 --- Polyhedral domain --- p.33 / Chapter 4.3.2 --- Rectangular domain --- p.38 / Chapter 5 --- Fully Discretization of the Maxwell's Equations --- p.63 / Chapter 5.1 --- Derivation --- p.63 / Chapter 5.2 --- Consistency theory --- p.65 / Chapter 5.3 --- Convergence theory --- p.69 / Chapter 5.3.1 --- Polyhedral domain --- p.69 / Chapter 5.3.2 --- Rectangular domain --- p.77 / Chapter 6 --- Numerical Tests --- p.97 / Chapter 6.1 --- Convergence test --- p.97 / Chapter 6.2 --- Electromagnetic scattering --- p.99 / Bibliography --- p.102
264

Design and modeling of a micro vibration-based power generator.

January 2000 (has links)
Chan Ming-Ho Gordon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 104-105). / Abstracts in English and Chinese. / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- BACKGROUND ON MICRO POWER SUPPLY --- p.1 / Chapter 1.1.1 --- Brief Introduction --- p.1 / Chapter 1.1.2 --- Proposed Applications of Micro Power Supplies --- p.3 / Chapter 1.1.3 --- Comparison Among Different Power Sources --- p.4 / Chapter 1.2 --- LITERATURE SURVEY --- p.8 / Chapter CHAPTER 2 --- MICRO POWER GENERATOR WITH COPPER SPRINGS --- p.10 / Chapter 2.1 --- POWER PRODUCTION FROM MECHANICAL VIBRATIONS: SYSTEM ANALYSIS --- p.10 / Chapter 2.2 --- DESIGN OF MICRO RESONATING SPRING --- p.16 / Chapter 2.2.1 --- Design Objective --- p.16 / Chapter 2.2.2 --- Material Selection --- p.18 / Chapter 2.2.2.1 --- Mechanical Resonating Structure --- p.18 / Chapter 2.2.2.2 --- Electromagnetic Structure --- p.23 / Chapter 2.3 --- LASER MICROMACHINING OF SPRING STRUCTURE --- p.26 / Chapter 2.3.1 --- Si Bulk Micromachining --- p.26 / Chapter 2.3.2 --- Laser Micromachining --- p.28 / Chapter CHAPTER 3 --- COMPUTER SIMULATION --- p.31 / Chapter 3.1 --- TRANSIENT VOLTAGE AND POWER OUTPUT --- p.31 / Chapter 3.2 --- SYSTEM RESPONSE WITH VARYING PARAMETERS --- p.35 / Chapter CHAPTER 4 --- FINITE ELEMENT ANALYSIS --- p.39 / Chapter 4.1 --- STRUCTURAL STATIC ANALYSIS --- p.41 / Chapter 4.1.1 --- Building a Model --- p.41 / Chapter 4.1.2 --- "Material, Loading And Boundary Condition" --- p.45 / Chapter 4.1.3 --- Comparison Between Generator Designs --- p.46 / Chapter 4.2 --- MODAL ANALYSIS AND HARMONIC RESPONSE ANALYSIS --- p.51 / Chapter 4.3 --- NONLINEARITY --- p.52 / Chapter CHAPTER 5 --- COMPARISON OF MODELING AND EXPERIMENTAL RESULTS --- p.55 / Chapter 5.1 --- EXPERIMENT SETUP --- p.55 / Chapter 5.1.1 --- Generator System --- p.55 / Chapter 5.1.2 --- Vibration and Measurement --- p.60 / Chapter 5.2 --- MODELING AND EXPERIMENTAL COMPARISON --- p.62 / Chapter 5.2.1 --- Voltage and Power Comparison --- p.64 / Chapter 5.2.2 --- Mechanical Response --- p.66 / Chapter CHAPTER 6 --- SUGGESTIONS FOR POWER GENERATOR WITH RESONATING FREQUENCY BELOW 10HZ --- p.77 / Chapter CHAPTER 7 --- CONCLUSION --- p.80 / BIBLIOGRAPHY --- p.104
265

Numerical modelling of masonry arch bridges : investigation of spandrel wall failure

Wang, Junzhe January 2014 (has links)
Masonry arch bridges still play an important role in the transportation infrastructure today in the United Kingdom. Previous research has mainly focused on the load carrying capacity in the span direction. The three dimensional behaviour is often investigated by simplifying into two dimensions with modified arch parameters but these simplified analyses cannot represent all aspects of behaviour. Spandrel wall failure in some railway masonry arch bridges has raised concerns recently, and this is one aspect which cannot be modelled in two dimensions. This thesis presents a research which attempts to model the interaction behaviour between arch, backfill and spandrel wall with the aim of representing the three dimensional nature of real bridges. It mainly focuses on the spandrel wall defects under increasing load, including crack development across the wall and longitudinal cracks in the arch barrel underneath spandrel wall. Experimental results from the laboratory tests on engineering blue brick and a hydraulic premixed mortar as well as brickwork masonry specimens are presented. Numerical analysis was initially performed on these brickwork masonry specimens for validation. Three dimensional FE models were proposed for both small and large scale bridges. The general behaviour of the small scale bridge under rolling load and large scale bridge under increasing load were studied. Reasonable agreement between the FE analyses and experimental results from previous literature was obtained, indicating the model validated for small masonry specimens could be scaled up to full-scale bridges. A series of computer models were constructed to investigate the relationship between a range of geometric and material parameters and the lateral behaviour of arch bridges. The backfill depth and spandrel wall thickness have greatest impact on both bridge strength and lateral behaviour. The fill properties also have an importance influence on the load carrying capacity. This provides an indication of which bridge should be more closely monitored for spandrel wall defects. Separate FE models was constructed to simulate existing longitudinal cracks found in the arch barrel for old bridges and the influence of strengthening of spandrel wall with tie bars. The general behaviour under a concentrated load is studied and discussed. It has been demonstrated that it is possible to effectively model the three dimension behaviour of masonry arch bridges and in particular, spandrel wall failures.
266

Finite Element Method Modeling of Optoconductance in Metal-Semiconductor Hybrid Devices

Girgis, Alexi M 16 November 2010 (has links)
"A numerical description of the extraordinary optoconductance (EOC) effect is presented using two separate models. Extraordinary optoconductance is part of a general class of EXX geometric effects involving the external perturbation of the properties of a 2D electron gas in a macroscopic semiconductor or metal-semiconductor hybrid structure. The addition of metallic inclusions, has been shown to increase the sensitivity of devices relying on EXX effects. Following the discovery of the first EXX effect, extraordinary magneto-resistance (EMR), an optical equivalent was suggested. Unlike EMR, where the external perturbation is an applied magnetic field, EOC results from the modification of the local charge density in the semiconductor by a focused laser. The first model assumes Gaussian charge densities for the photo-generated electron-hole pairs while the second model directly solves the semiconductor drift-diffusion equations using the finite element method (FEM). Results from both models are shown to agree with experimental EOC data, both as a function of the laser spot position and temperature. The FEM model has the ability to describe EOC in more complex geometries making it useful in designing EOC devices geared for particular applications. "
267

Numerical Solution of a Transmission Problem with Prefractal Interface

Wasyk, Rebecca Dawn 04 December 2007 (has links)
"Certain physical problems in electrostatics, magnetostatics, and heat transfer give rise to elliptic boundary value problems with transmission conditions on a layer. We focus on a particular problem with a second order transmission condition, representing an infinitely conductive layer. To approximate irregular layers that may naturally arise, a sequence of layers that converge to the fractal von Koch curve is considered. The solution to this transmission problem with a prefractal layer exhibits singularities due to the transmission condition across the layer as well as the reentrant corners introduced in the domain by the prefractal curve. To solve this problem numerically using a finite element method, the mesh must be adjusted to account for these singularities. We exhibit a general algorithm for creating a finite element discretization of the domain that results in linear convergence of the numerical solution to the true solution in a suitable norm."
268

Design of a non-snagging guardrail post

Karlsson, Jessica E 23 June 2000 (has links)
"The purpose of this project is to design a non-snagging guardrail post. The procedure will be to first develop a simple finite element (FE) model of a single post, wheel and suspension to explore the snag potential for some existing standard guardrail posts. The next step in the procedure will be to develop appropriate design changes that could prevent wheel snagging and investigate if they do by using a one-post sub-model. An attempt to validate the used material model for wood will also be done by comparison between laboratory tests and finite element simulations."
269

An investigation of the performance of mortise and tenon joints using the finite element method

Mihailescu, Teofil January 1999 (has links)
No description available.
270

Hermite–Lagrangian finite element formulation to study functionally graded sandwich beams

Universidad Peruana de Ciencias Aplicadas (UPC), Yarasca, J., Mantari, J.L., Arciniega, R.A. 04 1900 (has links)
This paper presents a static analysis of functionally graded single and sandwich beams by using an efficient 7DOFs quasi-3D hybrid type theory. The governing equations are derived by employing the principle of virtual works in a weak form and solved by means of the Finite Element Method (FEM). A C1 cubic Hermite interpolation is used for the vertical deflection variables while C0 linear interpolation is employed for the other kinematics variables. Convergence rates are studied in order to validate the finite element technique. Numerical results of the present formulation are compared with analytical and FEM solutions available in the literature. / Revisión por pares

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