Hui-Ming Fang

A drbem model for harbor oscillation with the effect of energy dissipation

Abstract In this study, the numerical scheme of dual reciprocity boundary element method (DRBEM) is adopted to investigate the resonant problem in a harbor while considering the effect of energy dissipation. The numerical model employed the mild slope equation as a basic equation. To avoid complicated procedures for solving the equation, DRBEM is used to improve numerical efficiency. Computation results are compared with the existing experimental data and other theoretical results. It shows that the present model is valid and effective to solve the harbor oscillation problem.

DISCUSSION ON THE MAXIMUM STORM RADIUS EQUATIONS WHEN CALCULATING TYPHOON WAVES

In this paper, we conducted a series of numerical experiments to find the most suitable maximum wind speed radii for the parameterized typhoon model. Different maximum wind speed radius equations were used to generate different wind fields, which were then input into the MIKE21 Spectral Wave (SW) model. The wave height results from the MIKE21 SW model were compared with the measured results, and rootmean-square error (RMSE) analysis was conducted to find a good maximum wind speed radius equation for use as the basis for wind field generation in the future. The RMSEs were then scored according to this order. The lowest score indicated the best choice for the maximum wind speed radius equation. The SG02 equation (Silva et al., 2002) is the best maximum wind speed radius equation, was followed by the WA78 equation (Wang, 1978), it means that the radius of maximum wind is set to be 10% of the radius of Beaufort Scale 7 wind. For convenience of calculation, we recommend the WA78 equation, which is a reliable maximum wind speed radius equation.

Yanliao Beach Nourishment Methods

Yanliao Beach, part of Taiwans Northeast Coast National Scenic Area, is a major sightseeing and recreation spot. In recent years, the number of tourists has increased, and maintaining the beachs recreation function has become crucial. In 2007, Typhoon Krosa caused substantial beach erosion at Yanliao Beach; sand dunes collapsed, resulting in a beach scarp and endangering facilities toward the back of the beach. To protect the sand dunes and beach scarp of the post-typhoon topography, based on long-term Yanliao Beach topographic survey information and long-term tidal water level records, this study conducted an integrated artificial beach nourishment method that comprised replenishing the coastal beach and dunes. The planned areas for sand replenishment were those above the mean high water line. This beach nourishment measure protected the dunes from collapsing further and mitigated the risk of beach nourishment polluting the water in front of the beach. Topographic survey results revealed that the large amount of sand deposited in the intertidal zone resulted in the 0 m shoreline advancing toward the seaside. The width of the beach increased, indicating the success of this integrated beach nourishment method.

APPLICATION OF A RESIDUAL-NORM-BASED ALGORITHM TO SOLVE ELLIPTIC BOUNDARY VALUE PROBLEMS

In this study, we use a residual-norm-based algorithm (RNBA) to solve nonlinear elliptic boundary value problems (BVPs) on an arbitrary planar domain. For complex geometries, BVPs are very difficult and time-consuming to solve using conventional finite difference methods (FDMs). To overcome these problems, we apply a novel finite difference method (NFDM). By adding a fictitious rectangular domain and a bilinear function, we can easily treat geometrically complex boundary conditions. Then, through the use of the internal residual and the boundary residual, we can easily obtain the solution without the necessity of computing a matrix inverse. The RNBA avoids the oscillations that can occur in the manifold-based exponentially convergent algorithm (MBECA) by maintaining the manifold properties while guaranteeing convergence order greater than one. The accuracy and the convergence behaviour of this new method are demonstrated with several examples.

The Kriging Cloud Computing Framework: Interpolation of Topography by Cloud Computing with the Kriging Algorithm

Spatial information surveyed by photogrammetry, airborne LiDAR and Mobile Measurement System (MMS) above ground level can be analyzed by scientists using standard geostatistical methodologies such as ordinary Kriging and sequential Gaussian simulation to interpolate heterogeneities of profiles from sparse sample data. Proven effective by researchers, the Kriging algorithm model is used by commercial data analysis packages for instant interpolation. However, meaningful and reliable results only come with a comprehensive understanding of the variogram associated with valid mathematical functions. To capture spatial landscape variations from massive sample grids of satellite images, this paper presents a cloud computing-based automation approach to improve topography interpolation by taking advantage of rapid computation speed through an open-source cross platform to enrich internet applications. The research team conducted a pilot test on sand beaches, developed the Kriging Cloud Computing Framework, streamlined the Kriging algorithm, developed Kriging Variogram Data Bank and Parameter Management System, derived cross validation procedures and built in Application Programming Interface, API. This new technology can benefit end users around the world in acquiring of ground profiles and production of Digital Elevation Models (DEMs) while requiring only minimal knowledge of the Kriging Method. This cloud computing system facilitates user data input, parameter selection, fast data analysis and model output. The application of this new framework improves remote sensing technology and GIS applications in a variety of unreachable terrains, such as deserts, swamps, and dense forests.

The Least Squares Trefftz Method and the Method of External Source for the Eigenfrequencies of Waveguides

In this study, the least squares Trefftz method (LSTM) is adopted for analyzing the eigenfrequencies problems governed by homogeneous Helmholtz equations. The Trefftz method, one kind of boundary-type meshless collocation methods, does not need mesh generation and numerical quadrature. Since the system of linear algebraic equations obtained by Trefftz method is highly ill-conditioned, the least squares method is adopted to stabilize the numerical scheme in this study. In the eigenproblem, the response amplitudes from an external source are used to determine the resonant frequencies. By adding an external source, the homogeneous boundary condition becomes inhomogeneous. Then we can employ the LSTM to easily solve this problem. In this paper, the LSTM and the method of external source are used to solve this eigenfrequencies problems governed by Helmholtz equations. Several numerical examples are provided to verify the accuracy and the simplicity of the proposed numerical scheme.