A GPU-based Two Dimensional Flood Simulation System

Kuo-Chan Hung,Chih-Yung Feng,Kun-Huai Cheng,Pei-Cheng Tsao1,Hung-Kwai Chen 한국방재학회 2016 Journal of Disaster Management Vol.1 No.1

Abstract A GPU-based flood simulation system is developed in this research. The system comprises two main components: a GPU-lized two bdimensional flood simulation model named GLMRT and a web-GIS user interface. GLMRT is designed and constructed with following features. First, GLMRT is constructed based on Lattice Boltzmann method(LBM) and two dimensional shallow water equations. Second, GLMRT is combined with sink/source terms including excess rainfall and pump-like drainage. Third, a dry-wet boundary determining mechanism is considered in GLMRT. Fourth, real DEM data can be used in simulating water movement on the land surface. Finally, GPU accelerated technique is integrated into GLMRT to overcome the issue of time cost in calculation. The web-GIS based user interface is built based on cloud platform to assist data flow organization and real time simulation. The interface integrates real DEM data and receives precipitation estimation products from the Taiwan Typhoon and Flood Research Institute(TTFRI) and Central Weather Bureau(CWB). The simulation results would be displayed on the web-GIS via file and database transfer. Besides, a real time rendering technique based on real time simulation is developed, too. The real time rendering technique displays the simulation results via memory on GPU device and eliminates the time cost in data output. GLMRT solves a 800-second simulation of Zengwen Reservoir virtual dam break with 2,046x1,525 DEM grids (40 m resolution) within 140.11 seconds on the NVIDIA Tesla K20c. Compare to the 60,919 seconds computation time on the Intel?? Xeon?? CPU X5650 2.66GHz, the GLMRT gets a speedup of 438x. On the other hand, using GLMRT alone to simulate a 12-hour rainfall duration induced inundation would spend about 1.2 hours, which can provide buffer time for the requirement of flood prevention operation. Abstract A GPU-based flood simulation system is developed in this research. The system comprises two main components: a GPU-lized two bdimensional flood simulation model named GLMRT and a web-GIS user interface. GLMRT is designed and constructed with following features. First, GLMRT is constructed based on Lattice Boltzmann method(LBM) and two dimensional shallow water equations. Second, GLMRT is combined with sink/source terms including excess rainfall and pump-like drainage. Third, a dry-wet boundary determining mechanism is considered in GLMRT. Fourth, real DEM data can be used in simulating water movement on the land surface. Finally, GPU accelerated technique is integrated into GLMRT to overcome the issue of time cost in calculation. The web-GIS based user interface is built based on cloud platform to assist data flow organization and real time simulation. The interface integrates real DEM data and receives precipitation estimation products from the Taiwan Typhoon and Flood Research Institute(TTFRI) and Central Weather Bureau(CWB). The simulation results would be displayed on the web-GIS via file and database transfer. Besides, a real time rendering technique based on real time simulation is developed, too. The real time rendering technique displays the simulation results via memory on GPU device and eliminates the time cost in data output. GLMRT solves a 800-second simulation of Zengwen Reservoir virtual dam break with 2,046x1,525 DEM grids (40 m resolution) within 140.11 seconds on the NVIDIA Tesla K20c. Compare to the 60,919 seconds computation time on the Intel?? Xeon?? CPU X5650 2.66GHz, the GLMRT gets a speedup of 438x. On the other hand, using GLMRT alone to simulate a 12-hour rainfall duration induced inundation would spend about 1.2 hours, which can provide buffer time for the requirement of flood prevention operation.

Acupuncture as a new cultural tourism product in Greater Bay Area – Stakeholders’ perspectives

Wilco Chan Wai Hung,Luo Jim,Zhang Carol,Kuo Andy 한국마케팅과학회 2022 마케팅과학연구 Vol.32 No.1

Qi is a body network other than blood, nerve and lymph network being recognized by western medication and is identified by Chinese in thousand years ago. However, Qi network still remains relatively vague in the eyes of many scientists and people nowadays, despite the fact that Americans are adopting acupuncture as one of the medical treatments. Presently, a growing number of international tourists were found to be interested in learning more about the Chinese culture, particularly the Qi and acupuncture. It is conceivable that a combination of Qi knowledge and therapy devices can turn into an additional tourism attraction in China for international tourists. Interviews with specialists were conducted to receive valuable stakeholders’ viewpoints about the barriers and alternatives to develop the proposed tourism product.

Impact of fine fillers on flowability, fiber dispersion, strength, and tensile strain hardening of UHPC

Chung-Chan Hung,Kuo-Wei Wen,Yueh-Ting Chen Techno-Press 2023 Advances in concrete construction Vol.15 No.6

While ultra-high performance concrete (UHPC) is commonly reinforced with micro straight steel fibers in existing applications, studies have indicated that the use of deformed steel macro-fibers leads to enhanced ductility and post-peak responses for UHPC structural elements, which is of particular importance for earthquake-resistant structures. However, there are potential concerns regarding the use of UHPC reinforced with macro-fibers due to the issues of workability and fiber distribution. The objective of this study was to address these issues by extensively investigating the restricted and non-restricted deformability, filling ability, horizontal and vertical velocities, and passing ability of UHPC containing macro hooked-end steel fibers. A new approach is suggested to examine the homogeneity of fiber distribution in UHPC. The influences of ultra-fine fillers and steel macro-fibers on the workability of fresh UHPC and the mechanics of hardened UHPC were examined. It was found that although increasing the ratio of quartz powder to cement led to an improvement in the workability and tensile strain hardening behavior of UHPC, it reduced the fiber distribution homogeneity. The addition of 1% volume fraction of macro-fibers in UHPC improved workability, but reduced its compressive strength, which is contrary to the effect of micro-fiber inclusion in UHPC.

The Effects of Executive Stock Options and Stock Bonuses on Payout Policies in Taiwan

Chia-Ying Chan,Vivian W. Tai,Chi-Hung Chan,Kuo-An Li 한국증권학회 2012 Asia-Pacific Journal of Financial Studies Vol.41 No.2

This study investigates how executive stock-based compensation affects the payout policies of a company. Stock bonuses, which are dividend-protected, induce executives to pay out cash dividends. Conversely, stock options, which are not dividend-protected, discourage the payment of dividends. We posit that the structure of executive stock-based compensation plays a crucial role in determining the payout policies of a firm, particularly for those firms with higher percentages of institutional investors and shareholders with ultimate controlling power. We further examine the effects of the 2008 stock option expensing policy reform in Taiwan as well as the repercussions, if any, that this policy had on payout choices in 2009. The empirical results not only indicate that executive stock-based compensation has a conspicuous influence on the payout policies of a firm, but also that there is a positive relation between stock bonuses and cash dividends. Furthermore, in the case of Taiwan, which has a relatively low corporate income tax rate, firms with higher percentages of shareholders with ultimate controlling power have less preference to pay cash dividends and greater preference to retain profits within the company.