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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.
21

A thermodynamic and dynamic Lagrangian model for icebergs a data-model intercomparison for the Southern Ocean /

Abrahamowicz, Maria. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Atmospheric and Oceanic Sciences. Title from title page of PDF (viewed 2008/05/13). Includes bibliographical references.
22

Mechanisms and modelling of landslides in Hong Kong /

Chen, Hong. January 1999 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 134-143).
23

High order finite elements for lagrangian computational fluid dynamics a thesis /

Ellis, Truman E. Kolkailah, Faysal A. January 1900 (has links)
Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on May 20, 2010. Major professor: Faysal Kolkailah, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Aerospace Engineering." "April 2010." Includes bibliographical references (p. 136-140).
24

Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics

Lee, Chun Hean January 2012 (has links)
Over the past few decades, dynamic solid mechanics has become a major field of interest in industrial applications involving crash simulation, impact problems, forging and many others to be named. These problems are typically nonlinear due to large deformations (or geometrical nonlinearity) and nonlinear constitutive relations (or material nonlinearity). For this reason, computer simulations for such problems are of practical importance. In these simulations, the Lagrangian formulation is typically used as it automatically satisfies the mass conservation law. Explicit numerical methods are considered to be efficient in these cases. Most of the numerical methods employed for such simulations are developed from the equation of motion (or momentum balance principle). The use of low-order elements in these numerical methods often exhibits the detrimental locking phenomena in the analysis of nearly incompressible applications, which produces an undesirable effect leading to inaccurate results. Situations of this type are usual in the solid dynamics analysis for rubber materials and metal forming processes. In metal plasticity, the plastic deformation is isochoric (or volume-preserving) whereas, the compressible part is due only to elastic deformation. Recently, a new mixed formulation has been established for explicit Lagrangian transient solid dynamics. This formulation, involving linear momentum, deformation gradient and total energy, results in first order hyperbolic system of equations. Such conservation-law formulation enables stresses to converge at the same rate as velocities and displacements. In addition, it ensures that low order elements can be used without volumetric locking and/or bending difficulty for nearly incompressible applications. The new mixed formulation itself shows a clear advantage over the classical displacement-based formulation, due to its simplicity in incorporating state-of-the-art shock capturing techniques. In this research, a curl-preserving cell centred finite volume computational methodology is presented for solving the first order hyperbolic system of conservation laws on quadrilateral cartesian grids. First, by assuming that the approximation to the unknown variables is constant within each cell. This will lead to discontinuities at cell edges which will motivate the use of a Riemann solver by introducing an upwind bias into the evaluation of the numerical flux function. Unfortunately, the accuracy is severely undermined by an excess of numerical dissipation. In order to alleviate this, it is vital to introduce a linear reconstruction procedure for enhancing the accuracy of the scheme. However the second-order spatial method does not prohibit spurious oscillation in the vicinity of sharp gradients. To circumvent this, a nonlinear slope limiter will then be introduced. It is now possible to evolve the semi-discrete evolutionary system of ordinary equations in time with the aid of the family of explicit Total Variation Diminishing Runge Kutta (TVD-RK) time marching schemes. Moreover, a correction procedure involving minimisation algorithm for conservation of the total angular momentum is presented. To this end, a number of interesting examples will be examined in order to demonstrate the robustness and general capabilities of the proposed approach.
25

A Mathematical Model for Optimizing Mini-Hub Locations of Distribution Centers in Urban Areas

Unknown Date (has links)
Logistics play a vital role in the prosperity of today’s cities, but current urban logistics delivery practices have proven problematic and to be causing various negative effects in cities. This study proposes an alternative method for delivering cargo with the leasing of a network of logistics hubs within urban areas for designated daily time intervals and handcart last-mile deliveries. The objective of the study is the development of a mathematical programming model for identifying the optimal number and locations of hubs for serving demand with the minimum cost, as well as the optimal times during the day for leasing the facilities, while also allocating hubs to customers. The problem is effectively solved by applying a Lagrangian relaxation and subgradient optimization approach. Numerical examples and a sensitivity analysis provide evidence of the robustness of the model and its ability to be effectively applied to address real problems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection
26

Lagrangian angles of foliation in R² under curve shortening flow.

January 2011 (has links)
Ma, Man Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 75-76). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.6 / Chapter 2 --- Basic notions in Riemannian geometry --- p.10 / Chapter 2.1 --- Basic manifold theory --- p.11 / Chapter 2.2 --- "Connection, curvature" --- p.19 / Chapter 2.3 --- Submanifold theory --- p.29 / Chapter 3 --- Basic facts in symplectic and complex geometry --- p.33 / Chapter 3.1 --- "Symplectic manifolds, Lagrangian submanifolds" --- p.34 / Chapter 3.2 --- Kahler and Calabi-Yau manifolds --- p.39 / Chapter 3.3 --- Calibration --- p.49 / Chapter 4 --- Mean curvature flow --- p.52 / Chapter 4.1 --- Basic equations in Lagrangian immersions --- p.53 / Chapter 4.2 --- Evolution equation for --- p.57 / Chapter 4.3 --- Evolution equations for H and θ --- p.62 / Chapter 5 --- Lagrangian angle of a foliation --- p.67 / Chapter 5.1 --- "Proof of equation (5.1), (5.2)" --- p.68 / Chapter 5.2 --- Main theorem --- p.70 / Chapter 5.3 --- Examples of invariant solution --- p.73 / Bibliography --- p.75
27

Lagrangian duality in convex optimization.

January 2009 (has links)
Li, Xing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 76-80). / Abstract also in Chinese. / Introduction --- p.4 / Chapter 1 --- Preliminary --- p.6 / Chapter 1.1 --- Notations --- p.6 / Chapter 1.2 --- On Properties of Epigraphs --- p.10 / Chapter 1.3 --- Subdifferential Calculus --- p.14 / Chapter 1.4 --- Conical Approximations --- p.16 / Chapter 2 --- Duality in the Cone-convex System --- p.20 / Chapter 2.1 --- Introduction --- p.20 / Chapter 2.2 --- Various of Constraint Qualifications --- p.28 / Chapter 2.2.1 --- Slater´ةs Condition Revisited --- p.28 / Chapter 2.2.2 --- The Closed Cone Constrained Qualification --- p.31 / Chapter 2.2.3 --- The Basic Constraint Qualification --- p.38 / Chapter 2.3 --- Lagrange Multiplier and the Geometric Multiplier --- p.45 / Chapter 3 --- Stable Lagrangian Duality --- p.48 / Chapter 3.1 --- Introduction --- p.48 / Chapter 3.2 --- Stable Farkas Lemma --- p.48 / Chapter 3.3 --- Stable Duality --- p.57 / Chapter 4 --- Sequential Lagrange Multiplier Conditions --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- The Sequential Lagrange Multiplier --- p.64 / Chapter 4.3 --- Application in Semi-Infinite Programs --- p.71 / Bibliography --- p.76 / List of Symbols --- p.80
28

Relativistic field-theoretical transport in condensed matter

Vischer, Axel P. 14 February 1992 (has links)
We discuss a relativistic transport theory of condensed matter based on a microscopic system containing bosonic and fermionic degrees of freedom interacting via 3 - and 4-point interactions. We use the Dyson hierarchy as a solution to the underlying field theory and truncate this hierarchy by parametrizing the 2-particle-irreducible kernels of the 4- and 5-point vertex functions. We then perform a complete crossing-symmetric reduction of the 2-particle intermediate states of the theory. We obtain a reduction hierarchy and show how to explore the quality of our truncation scheme using this reduction hierarchy. Finally we discuss the problem of regularization of the theory in the case of hadronic matter by either putting form factors directly in the action or by using dispersion relations to introduce causal form factors into singular diagrams. / Graduation date: 1992
29

A finite element method for ring rolling processes

Dewasurendra, Lohitha. January 1998 (has links)
Thesis (Ph. D.)--Ohio University, June, 1998. / Title from PDF t.p.
30

Energy and momentum conservation in Bohm's Model for quantum mechanics

Hall, Bryan. January 2004 (has links)
Thesis (Ph. D.)--University of Western Sydney, 2004. / Includes bibliographical references.

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