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Verification of a Western Pacific Circulation Model Using Global Drifter DataYu, Sing-ru 29 August 2008 (has links)
The marine currents around the Pacific Northwest are researched by lots of scholars. The methods of the on-site observation, such as the shipping measurements and data buoys, were applied by researcher in the past. However, it is difficult to get comprehensive information on space by early methods, and it is often limited by the manpower and funding. With computer technology advances, numerical models get improving the accuracy and resolution. Therefore, development of the numerical models also becomes one of the methods to understand the ocean.
There are many current models and large databases which are developed. However, few studies combine the two. Therefore, this study adopts the simulated results of POLCOMS (Proudman Oceanographic Laboratory Coastal-Ocean Modeling System) in 2002 near the northwest Pacific (9.9¢X N ~ 41.9¢X N, 104.9¢X E ~ 139.9¢X E) to analyze some situations. The result can be compared with the measured data, and test the model.
In order to evaluate the accuracy of the results of the model, the simulated tracks can be calculated by the result of the model and the initial location of the measured data. However, the resolutions of time and space are only one day and 7.5 degree. Hence, the methods of linear interpolation and bilinear interpolation are applied to interpolate the model result in the time dimension and space dimension. By using the latitude and longitude of the initial points, the azimuth, and the geographic distance, the simulated tracks can be calculated. Therefore, the results of POLCOMS can be confirmed by global drifter data from NOAA/AOML.
According to the results of evaluating, the simulation trends of the seasons are similar to measured data. It can prove that this model has a certain degree of accuracy. However, simulation and the measured data can not be completely similar when abnormal weather phenomenon occurs. It is because the model was driven by the average wind field. There are suggestions to make the model complete by adding the weather information during the periods of the typhoons. Besides, the model can simulate the temperature and salinity of the ocean. Increasing the comparison of them will make the model integrated in the future, and obtain more correct information of the flow fields around the Pacific Northwest.
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A new finite element method for elliptic interface problemsLoubenets, Alexei January 2006 (has links)
<p>A finite element based numerical method for the two-dimensional elliptic interface problems is presented. Due to presence of these interfaces the problem will contain discontinuities in the coefficients and singularities in the right hand side that are represented by delta functionals along the interface. As a result, the solution to the interface problem and its derivatives may have jump discontinuities. The introduced method is specifically designed to handle this features of the solution using non-body fitted grids, i.e. the grids are not aligned with the interfaces.</p><p>The main idea is to modify the standard basis function in the vicinity of the interface such that the jump conditions are well approximated. The resulting finite element space is, in general, non-conforming. The interface itself is represented by a set of Lagrangian markers together with a parametric description connecting them. To illustrate the abilities of the method, numerical tests are presented. For all the considered test problems, the introduced method has been shown to have super-linear or second order of convergence. Our approach is also compared with the standard finite element method.</p><p>Finally, the method is applied to the interface Stokes problem, where the interface represents an elastic stretched band immersed in fluid. Since we assume the fluid to be homogeneous, the Stokes equations are reduced to a sequence of three Poisson problems that are solved with our method. The numerical results agree well with those found in the literature.</p>
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Some PDAE aspects of the numerical simulation of CO2 heat pumpStrömgren, Magnus January 2006 (has links)
<p>We consider network modelling and numerical simulation of a simple CO<sub>2</sub> heat pump consisting of a compressor, a valve and two heat exchangers. In a first step we investigate analytical and numerical properties of the heat exchanger model. The heat exchanger model is derived from the Euler equations under the assumption that the velocity of the refridgerant flow is small compared to the local speed of sound. While the Euler equations form a hyperbolic system, the character of the new system, called The zero Mach number limit of the Euler equations, is unclear. The lack of a time derivative in the momentum equation makes the heat exchanger model by itself a PDAE system.</p><p>We analyse a frozen-coefficient linearisation of the heat exchanger model by transformation to a canonical form. The canonical form reveales that the system is equivalent to a hyperbolic equation and a parabolic block. The parabolic block is equivalent to a parabolic equation and an algebraic-differential relation, similar to the system that results when the heat equation <i>ut = uxx + f </i>is written as a first order system. We prove a stability estimate suggesting that the solution is more sensitive to perturbations, especially in time-dependent boundary conditions, than is indicated by previous results.</p><p>Furthermore, we consider semidiscretisation of the linearised heat exchanger model. In a method of lines approach using collocation at the gridpoints, we suggest that it is possible to use a simple first order difference scheme taking into account the direction of the flow and the boundary conditions. We show that using this difference scheme, the solution to the semidiscrete equations satisfies a discrete analogue to the stability estimate in the continuous case.</p><p>The results of the linear analysis is verified in numerical experiments with the nonlinear heat exchanger model.</p>
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Using technology for real-time coordination of work : a study of work and artifact use in the everyday activities at SOS AlarmNormark, Maria January 2002 (has links)
<p>Work in control rooms, or so-called Centers of coordination, places demands both on humans and technology. The people working there have to be able to make quick decisions as well as be alert during less busy times. The work has to be coordinated within the group, since the operators are much depending on each other's work. This places special demands on the technology; it should be fast, trustworthy and easy to manipulate so that the complexity of the work is reduced. This type of work has been a source of interest in the research area of Computer Supported Cooperative Work, especially so since the needs for real-time coordination is great in these settings.</p><p>SOS Alarm is a company that is responsible for managing the telephone calls made to the emergency number 112 in Sweden. They have 20 centers covering Sweden. This thesis present an overview of the SOS operators work; how they coordinate the information and tasks between them; how the technology supports that work. This study presents a fully computerized setting, compared to many other studies of centers of coordination that are not.</p><p>This ethnographic workplace study has been inspired by ethnomethodological perspectives as well as earlier field studies of work and technology use. Its main results are a description of the work practice and technology at two centers, implications for design of a new computer aided dispatch system that is currently developed at SOS Alarm and general design ideas for control rooms.</p>
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Numerical analysis of two dimensional natural convection heat transfer following a contained explosion /Manson, Steven James, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 515-522). Available also in a digital version from Dissertation Abstracts.
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Variable shape parameter strategies in radial basis funchtion methodsSturgill, Derek Joseph. January 2009 (has links)
Thesis (M.A.)--Marshall University, 2009. / Title from document title page. Includes abstract. Document formatted into pages: contains xii, 104 p. Includes bibliographical references p. 99-104.
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The numerical weather prediction system at the Italian Air Force Weather Service : impact of non-conventional observations and increased resolution /Torrisi, Lucio. January 2004 (has links) (PDF)
Thesis (M.S. in Meteorology)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Roger T. Williams. Includes bibliographical references (p. 91-95). Also available online.
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Biosystematics of the Phacelia ranunculacea complex (Hydrophyllaceae)Sewell, Matthew. January 2003 (has links)
Thesis (M.S.)--Miami University, Dept. of Botany, 2003. / Title from first page of PDF document. Document formatted into pages; contains v, 53 p. : ill. Includes bibliographical references (p. 24-26).
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Numerical analysis of dynamic crack propagation /Wu, See-loi. January 1988 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1988.
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The L-numerical range : liear image of joint unitary orbit of hermitian matrices /Chan, Yiu-Kwong. January 2002 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 53-56).
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