Browsing by Author "Chang, Hsien-Kuo"

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103年臺北港風與波浪關連性之統計特性研究
(2014)
張憲國
;
Chang, Hsien-Kuo
;
國立交通大學
目前以方程式建構的數值模式或經驗公式推算波浪可能產生之誤差，其原因部分來自於給定的風速與實際值有差異，因為波浪模式所用的風速為海面上10m之風速。此海面10m風速值在台灣上少有實測資料，而改引用陸上或高空衛星觀測值來取代。交通部運輸研究所港灣技術研究中心已在台北港外海設置一個觀測樁，同時測量波浪與風速，波浪以觀測樁水下-5m及-10m處各安裝無線電傳輸之潮波流儀來觀測，在觀測樁之海面上10m處有自記式之風速儀。本計畫主要探討同時觀測風速及波浪資料的統計特性，並建立兩者間之關係。本計畫將以長期資料進行海上與陸上風速測站資料的分析與特性比較，並評估向岸風與離岸風速之成分及時間分布特性以瞭解臺北港地形對風速發展的影響。另以不同季節或月份進行風速與方向的分類，以了解臺北港在不同季節與氣候特性下的風速及方向特性。最後採用不同風速尺度進行其持續性(persistence)的分析，考量海面風速強度、吹送角度與持續性(persistence)進行風浪相關性分析，以改善風浪推算的經驗公式。
96年高雄港域波流場數值模擬及特性研究
(2007)
張憲國
;
Chang, Hsien-Kuo
;
國立交通大學土木工程研究所
本計畫將分為兩部分進行，一部份應用高雄港內外海象觀測資料，建立高雄港現有及未來擴建港域之流場分析數值模式，用以瞭解港內外全面性之流場分布及流況改變情況；另一部份則將分析高雄港海域波浪特性，同時透過極值統計分析方式，分析高雄港的波浪設計條件，並應用高雄港的颱風波浪資料，配合相對應颱風路徑、規模及陸地效應分類，以類神經網路與模糊理論建立颱風波浪預報模式，最後透過圖形化使用者界面之視窗化操作系統，提供高港局船隻作業及營運維護之參考依據。
97年高雄港域波流場數值模擬及特性研究
(2008)
張憲國
;
Chang, Hsien-Kuo
;
國立交通大學土木工程研究所
本計畫將進行兩部分研究，一部份應用高雄港內外海象觀測資料，建立高雄港未來擴建港域之流場分析數值模式，透過96年度與今年度的模擬結果，比較高雄港擴建前後之流場分布及流況改變之差異；另一部份則分析高雄港海域波浪特性，利用樣本機率密度之直方圖與參數化之機率密度函數比對，探討高雄港域最適之波高與週期分布函數，同時透過極值統計分析方式，分析高雄港的波浪設計條件，提供高港局船隻作業及營運維護之參考依據。
A fuzzy-neural hybrid system of simulating typhoon waves
(2006-07-01)
Chang, Hsien-Kuo
;
Chien, Wei-An
;
土木工程學系
;
Department of Civil Engineering
This study addresses a fuzzy-neural hybrid system of simulating typhoon waves. A membership function based on the fuzzy theory is expressed by a union Gaussian function to illustrate the rapid wave decaying. Four areas separated by two lines which intersect at the Hua-Lien harbor indicate the case of typhoon's position and propagation. Better simulation performance of the peak wave heights and their occurrence time in both the learning stage and the verification stage simulated by the NF2 model than by the NF1 model is identified. The wave decaying due to land effect is well described by the NF2 model. The NF2 model is applicable for well simulating typhoon waves during the whole period of a typhoon approaching to Taiwan. (c) 2006 Elsevier B.V All rights reserved.
An adaptive neuro-fuzzy inference system for sea level prediction considering tide-generating forces and oceanic thermal expansion
(2008-04-01)
Lin, Li-Ching
;
Chang, Hsien-Kuo
;
土木工程學系
;
Department of Civil Engineering
The paper presents an adaptive neuro fuzzy inference system for predicting sea level considering tide-generating forces and oceanic thermal expansion assuming a model of sea level dependence on sea surface temperature. The proposed model named TGFT-FN,(Tide-Generating Forces considering sea surface Temperature and Fuzzy Neuro-network system) is applied to predict tides at five tide gauge sites located in Taiwan and has the root mean square of error of about 7.3 - 15.0 cm. The capability of TGFT-FN model is superior in sea level prediction than the previous TGF-NN model developed by Chang and Lin (2006) that considers the tide-generating forces only. The TGFT-FN model is employed to train and predict the sea level of Hua-Lien station, and is also appropriate for the same prediction at the tide gauge sites next to Hua-Lien station.
Beach Erosion and Preventive Countermeasure at Kangnan Coast, Taiwan
(2009-03-01)
Liou, Jin-Cheng
;
Chang, Hsien-Kuo
;
Chen, Wei-Wei
;
Liaw, Shyne-Ruey
;
土木工程學系
Kangnan Coast has suffered from beach erosion since the extension of breakwaters and two groins of Hsinchu Fishing Harbor was completed. This is a typical example of human impact on coastal erosion in Taiwan. The aim of this article is to explore the erosion at Kangnan Coast using several analyses, such as shoreline revolution detected from satellite images, planform description of depth variation, volumetric change of bathymetry, and variations in the trends of volumetric changes of the sea bottom. Beach erosion at Kangnan Coast in response to structural effects was quantitatively determined. A suggested countermeasure using submerged detached breakwaters, developed through a 3-year study, is proposed to mitigate beach erosion.
Long wave reflection from submerged trapezoidal breakwaters
(2007-01-01)
Chang, Hsien-Kuo
;
Liou, Jin-Cheng
;
土木工程學系
;
Department of Civil Engineering
This study addresses the reflection and transmission of long waves from a trapezoidal breakwater and a series of trapezoidal breakwaters, using the matching method. A systematic shape transfer is derived to determine wave reflection and transmission. The peak Bragg reflection of long waves from a series of trapezoidal breakwaters is shifted toward low frequency. In spite of the spacing between any pair of breakwaters, the top plane width and the arrangement of the series of breakwaters are found to be the two major parameters in designing multiply composite Bragg breakwaters. (C) 2006 Elsevier Ltd. All rights reserved.
Multi-point tidal prediction using artificial neural network with tide-generating forces
(2006-09-01)
Chang, Hsien-Kuo
;
Lin, Li-Ching
;
土木工程學系
;
Department of Civil Engineering
This paper presents a neural network model of simulating tides at multi-points considering tide-generating forces. A comparison on the root mean square and correlation coefficient of three-year mixed tides at a single point computed with harmonic method, response-orthotide method, the NAO.99b model and the proposed model was made to show the prediction accuracy of each method. The proposed model is examined efficient as the harmonic method to estimate the tides at a single point. Extended application of the proposed model to predicting tides at some points neighboring to an original interest point identifies accurately simulating multi-point tides as the NAO.99b numerical model. (C) 2006 Elsevier B.V. All rights reserved.
Particle trajectories of nonlinear gravity waves in deep water
(2009-04-01)
Chang, Hsien-Kuo
;
Chen, Yang-Yi
;
Liou, Jin-Cheng
;
土木工程學系
;
Department of Civil Engineering
The paper presents a numerical method for calculating the particle trajectories of nonlinear gravity waves in deep water. Particle trajectories, mass-transport velocity and Lagrangian wave period can be accurately determined by the proposed method. The high success rate of the proposed method is examined by comparing the present results with those of(a) Longuet-Higgins, M.S., 1986,1987. Eulerian and Lagrangian aspects of surface waves. journal of Fluid Mechanics 173, 683-707 and (b) Lagrangian moments and mass transport in Stokes waves. Journal of Fluid Mechanics 179,547-555. It is shown that the dimensionless mass-transport velocity can exceed 10% for large waves, and the Lagrangian wave period is much larger than the Eulerian wave period for large waves. (C) 2009 Elsevier Ltd. All rights reserved.
Particle trajectory and mass transport of finite-amplitude waves in water of uniform depth
(2007-05-01)
Chang, Hsien-Kuo
;
Liou, Jin-Cheng
;
Su, Ming-Yang
;
土木工程學系
;
Department of Civil Engineering
A set of governing equations in Lagrangian form is derived for propagating gravity waves in water of uniform depth. The Lindstedt-Poincare perturbation method is used to obtain approximations up to fifth order. Recognizing the Lagrangian frequency to be a position function for all particles is a key to find these higher-order approximations. The present solution has zero pressure at the free surface and satisfies exactly the dynamic boundary condition. Under the present approximations, the Lagrangian frequency is composed of two parts. The first part is constant for all particles and equivalent to the term in the fifth-order Stokes' wave theory [J.D. Fenton, A fifth-order Stokes theory for steady waves, J. Waterway, Port, Coastal Ocean Eng. 111 (1985) 216-234]. The second part is a function of the depth. All the particles move as open (nonclosed) loops and have mean drift displacements that decrease exponentially with the water depth. Thus, a new fourth-order mass transport velocity is found. (c) 2006 Elsevier Masson SAS. All rights reserved.
Protection Priority in the Coastal Environment Using a Hybrid AHP-TOPSIS Method on the Miaoli Coast, Taiwan
(2012-03-01)
Chang, Hsien-Kuo
;
Liou, Jin-Cheng
;
Chen, Wei-Wei
;
土木工程學系
;
Department of Civil Engineering
CHANG, H.-K.; LIOU, J.-C., and CHEN, W.-W., 2012. Protection priority in the coastal environment using a hybrid AHP-TOPSIS method on the Miaoli Coast, Taiwan. Journal of Coastal Research, 28(2), 369-374. West Palm Beach (Florida), ISSN 0749-0208. Coastal erosion often happens around the island of Taiwan because of strong waves from typhoons in the summer. The problem of beach erosion cannot be completely solved at this time due to insufficient government budgets. Prioritization of coastal protection should be made yearly to match engineering requirements and annual official budgets. This paper proposes both analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS) methods to prioritize the protection of the coastal environment on the Miaoli Coast of Taiwan. The weights of three main criteria (engineering safety, ecology, and coastal landscape) and their subcriteria are determined through the AHP method. Twenty-two segments of the Miaoli Coast are ranked according protection priority by the TOPSIS method. This multipart methodology can help decision makers prioritize coastal engineering and environmental efforts. This procedure also enables researchers to put more expert knowledge together, allowing more precise decisions and moderating personal judgments.
Shifting the waterlines of satellite images to the mean water shorelines considering wave runup, setup, and tidal variation
(2015-09-25)
Chang, Hsien-Kuo
;
Chen, Wei-Wei
;
Liou, Jin-Cheng
;
土木工程學系
;
Department of Civil Engineering
Shoreline evolution is a simple and common method to illustrate beach erosion or accretion in coastal engineering. Extracted waterlines on different satellite images are sometimes used for shoreline evolution. However, time-varying waterlines for tidal variation and wave runup are different from the shoreline at the mean water level. Waterline evolution may bring about misunderstanding of beach erosion or accretion. In a former study, the one-line shift method was proposed to determine the waterlines on a satellite image and to shift the water-lines to shorelines while only considering the tidal variation. The upward shift extension of the waterline due to wave runup and wave setup is considered. Some acceptable equations of wave runup were examined to correct the waterlines on three satellite images in one month when the foreshore beach slopes were specified. The suggested equation for wave runup includes both wave conditions and an average beachface slope at two points located shoreward and seaward away from mean water level by an equal distance of 62.5 m. When on-site shore bathymetrical measurement is sometimes unavailable, a method of minimizing the difference between the initially guessed and estimated foreshore beach slopes by the one-line shift method is proposed. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
Simulated wave-driven ANN model for typhoon waves
(2011-01-01)
Chang, Hsien-Kuo
;
Liou, Jin-Cheng
;
Liu, Shen-Jung
;
Liaw, Shyne-Ruey
;
土木工程學系
This paper investigates an artificial neural network (ANN) model for typhoon waves used to modify poor calculations of the numerical model in special cases. Two key factors, local winds and simulated waves produced by the numerical model, were used as input parameters of the proposed ANN model. The waves were simulated by the numerical model from a wave action equation indicating the physical processes of energy transfer and wave propagation. Simulated wave input is a very important parameter for the proposed ANN model, allowing for the accurate calculation of water waves in the sea. The applicable Mike21_SW model was chosen to provide an accurate calculation. Through model verification, the proposed ANN model has a particularly accurate calculation at the peak of each typhoon and at its occurrence time. The computed waves of each typhoon were examined to be consistent with the observed waves. (C) 2010 Elsevier Ltd. All rights reserved.
臺北港風與波浪關連性之統計特性研究
(2012)
張憲國
;
Chang, Hsien-Kuo
;
國立交通大學
目前以方程式建構的數值模式或經驗公式推算波浪可能產生之誤差，其原因部分來自於給定的風速與實際值有差異，因為波浪模式所用的風速為海面上10m之風速。此海面10m風速值在台灣上少有實測資料，而改引用陸上或高空衛星觀測值來取代。交通部運輸研究所港灣技術研究中心已在台北港外海設置一個觀測樁，同時測量波浪與風速，波浪以觀測樁水下-5m及-10m處各安裝無線電傳輸之潮波流儀來觀測，在觀測樁之海面上10m處有自記式之風速儀。本計畫主要探討同時觀測風速及波浪資料的統計特性，並建立兩者間之關係。本計畫將透過波浪的長期資料進行基本統計與波譜分析，以瞭解不同時間下的各種統計特性，探討臺北港在各月份及季節波譜特性之參數，以提供未來分析波浪特性與工程實務應用之參考。本計畫同時考量海面風速強度、風向與持續性進行風浪相關性分析，並以風速、風向分布及風的持續性建立波浪波高及週期的關係。
臺灣國際港區船舶動態管理特性及颱風波浪資料補遺研究(II)
(2006)
張憲國
;
Chang, Hsien-Kuo
;
國立交通大學土木工程研究所
本計畫延續94年度之分析結果，利用花蓮港港務局所提供之船隻動態記錄，從波浪之觀測與船舶動態資料分析，於本年度欲建立預警模式予以港灣管理單位做即時的判斷與反應。另外94年度已建立初步之颱風波浪補遺模式，並以此進行模式之測試，由測試結果可獲得較佳的補遺精度，依其結果評估可應用為資料補遺之用。因此，本次計畫將利用類神經網路等技術，建立一個以港灣颱風特性與船隻異動關係之類神經網路模式，並針對颱風動態參數與觀測資料進行統計分析與分類，以期能建立有系統之颱風波浪統計模式及資料補遺模式之修正，進而能提高船隻預警管理之能力。