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RANS Modeling of Solitary Wave Propagation over A Submerged Rectangular Breakwater

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China Ocean Engineering 2009年第3期23卷 473-488页

作者： tai-wen hsu Chin-Yen TSAI Department of Hydraulic and Ocean Engineering National Cheng Kung University

In this paper a series of numerical simulations are performed to investigate the vortex shedding mechanism for a solitary wave propagating over a submerged breakwater by use of Reynolds averaged Navier-Stokes （RAINS） model combined with a k-ε model. Flows of different Reynolds numbers up to Re = 1.4 × 10^5 corresponding to varying incident wave heights are considered in which the characteristic fluid velocity is represented by the maximum horizontal velocity above the submerged breakwater. For the verification of the accuracy of the numerical model, the incident waves and the velocity field in the vicinity of the breakwater are compared with experimental data. The result shows that the model is capable of describing vortex shedding for a solitary wave propagating over a rectangular submerged breakwater. Key features of vortex generation, evolution and dissipation are investigated. It is found that the vortex shedding and their evolution due to separated boundary layer over the breakwater are strongly related to the Reynolds number. A considerable number of vortices and complicated vortex pattern are observed as the Reynolds number increases.

关键词： RANS modeling solitary wave vortex shedding submerged breakwater

A Note on the Derivation of Wave Action Balance Equation in Frequency Space

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China Ocean Engineering 2011年第1期25卷 133-138页

作者： tai-wen hsu Jian-Ming LIAU Shin-Jye LIANG Shan-Hwei OU Yi-Ting LI Department of Hydraulic and Ocean Engineering National Cheng Kung University taiwan Ocean Research Institute National Applied Research Laboratories Department of Marine Environmental Informatics National Taiwan Ocean University Department of Harbor and River Engineering National Taiwan Ocean University Institute of Ocean Technology and Marine Affairs National Cheng Kung University

In this paper the wave action balance equation in terms of frequency-direction spectrum is derived. A theoretical formulation is presented to generate an invariant frequency space to replace the varying wavenumber space through a Jacobian transformation in the wave action balance equation. The physical properties of the Jacobian incorporating the effects of water depths are discussed. The results provide a theoretical basis of wave action balance equations and ensure that the wave balance equations used in the SWAN or other numerical models are correct. It should be noted that the Jacobian is omitted in the wave action balance equations which are identical to a conventional action balance equation.

关键词： wave action balance equation wavenumber-spectrum frequency-spectrum Jacobian

Conceptual Modeling of Island Wake Interactions

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Conceptual Modeling of Island Wake Interactions

Spatial and Temporal Features of Regional Variations in Mean Sea Level around taiwan

第五届海峡两岸水动力学研讨会

作者： tai-wen hsu Meng-Hsien Chou Shin-Jye Liang Research Center for Ocean Energy and Strategies National Taiwan Ocean University Department of Hydraulic and Ocean Engineering National Cheng-Kung University Department of Marine Environmental Informatics National Taiwan Ocean University

Satellite images observed interactions of Lanyu Island wake and Green Island wake is numerical *** model is based on the depth-averaged shallow-water equations which are solved by the space-time least-squares finite-element *** results show downstream recirculations as well as island wakes of Lanyu Island and Green Island are well *** of Lanyu Island wake and Green Island wake are ***,a systematical and quantitative investigation is required to full understand the detailed interactions of Lanyu Island wake and Green Island wake.

关键词： island wakes least-squares finite-element method shallow-water equations

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Open Journal of Marine Science 2012年第2期2卷 58-65页

作者： Li-Chung Wu Chia Chuen Kao tai-wen hsu Yi-Fung Wang Jong-Hao Wang Coastal Ocean Monitoring Center National Cheng Kung University Tainan Chinese Taipei Department of Hydraulic and Ocean Engineering National Cheng Kung University Tainan Chinese Taipei Water Resources Agency Ministry of Economic Affairs Taipei Chinese Taipei

Satellite altimeter and in-situ tide gauge records are probably the most common means to obtain observational data for the study of changes in mean sea level. In this study, we employed these data to discuss the spatial and temporal features of regional variations in mean sea level around taiwan. The results showed that most of the regional mean sea surface heights (SSH) around taiwan are higher than the global mean sea surface heights. Most of the sea level trends are greater than the global mean sea level trend as well. We obtained diverse distribution results from the altimeter sea level records in neighboring areas by distributions fit, and the altimeter sea level records showed obvious inhomogene- ity. In addition, periodic fluctuations in the records regarding mean sea level were revealed in our study, based on Fourier spectra and wavelet scalograms.

关键词： Sea Level Variations Tide-Gauge Altimeter

Interannual variability of boreal summer intraseasonal oscillation over the northwestern Pacific influenced by the Pacific Meridional Mode

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 6-11页

作者： Haoyu Zhou Pang-Chi hsu Lin Chen Yitian Qian Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjingChina

During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis *** elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget *** findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern *** increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective *** a process is pivotal in amplifying intraseasonal convection *** observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.

关键词： Boreal summer intraseasonal oscillation Interannual variability Pacific Meridional Mode Moisture budget analysis

NUMERICAL WAVE FLUME WITH IMPROVED SMOOTHED PARTICLE HYDRODYNAMICS

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Journal of Hydrodynamics 2010年第6期22卷 773-781页

作者： ZHENG Jin-hai SOE Mee Mee ZHANG Chi hsu tai-wen State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing210098 China Department of Hydraulic and Ocean Engineering National Cheng Kung University Tainan 701 China

This paper presents an improved Nearest Neighboring Particle Searching （NNPS） technique for numerical modeling of water waves with the Smoothed Particle Hydrodynamics （SPH） method. The proposed technique differs from others by introducing the concept of Inner and Outer Particle Searching （lOPS） and shifting most of advanced CPU operations into simple addition operations. The IOPS method is shown to significantly improve the computational efficiency and reduce the CPU time especially for large number of particles, based on comparisons with other two NNPS methods. This method is implemented in a 2DV numerical wave flume conducted by the SPH method. Three test cases are examined, including generations and propagations of dam-breaking induced waves, solitary wave and irregular wave. Calculated results are in good agreements with experimental data and theoretical solutions with fairly satisfactory CPU time-consuming. The wave motions observed in physical facilities are successfully reproduced by the SPH numerical wave flume, revealing its robust capability of modeling realistic wave propagation and substantial potential for a wide variety of hydrodynamic problems.

关键词： particle searching technique Smoothed Particle Hydrodynamics (SPH) numerical wave flume Navier-Stokes equation

Bubble Size Distribution for Waves Propagating over A Submerged Breakwater

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China Ocean Engineering 2008年第2期22卷 227-240页

作者： TIEN Tsung-mo HUANG Ching-jer hsu tai-wen LEE Chien-hsun hsu Shi-sheng Department of Hydraulic and Ocean Engineering National Cheng Kung University

Experiments are carried out to study the characteristics of active bubbles entrained by breaking waves as these propagate over an abruptly topographical change or a submerged breakwater. Underwater sounds generated by the entrained air bubbles are detected by a hydrophone connected to a charge amplifier and a data acquisition system. The size distribution of the bubbles is then determined inversely from the received sound frequencies. The sound signals are converted from time domain to time-frequency domain by applying Gabor transform. The number of bubbles with different sizes are counted from the signal peaks in the time-frequency domain. The characteristics of the bubbles are in terms of bubble size spectra, which account for the variation in bubble probability density related to the bubble radius r. The experimental data demonstrate that the bubble probability density function shows a - 2.39 power-law sealing with radius for r 〉 0. 8 mm, and a- 1.11 power law for r 〈0.8 mm.

关键词： breaking waves submerged breakwater underwater noise Gabor transform bubble-size spectra

Acoustic radiation force impulse predicts long-term outcomes in a large-scale cohort:High liver cancer,low comorbidity in hepatitis B virus

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World Journal of Gastroenterology 2023年第14期29卷 2188-2201页

作者： Jennifer tai Adam P Harrison Hui-Ming Chen Chiu-Yi hsu Tse-Hwa hsu Cheng-Jen Chen wen-Juei Jeng Ming-Ling Chang Le Lu Dar-In tai Department of Gastroenterology and Hepatology Chang Gung Memorial HospitalTaoyuan 33305Taiwan Radiomics Group Q BioSan CarlosCA 94063United States Center for Big Data Analytics and Statistics Chang Gung Memorial HospitalTaoyuan 33305Taiwan DAMO Academy Alibaba GroupNew YorkNY 94085United States

BACKGROUND Acoustic radiation force impulse(ARFI)is used to measure liver fibrosis and predict *** performance of elastography in assessment of fibrosis is poorer in hepatitis B virus(HBV)than in other etiologies of chronic liver *** To evaluate the performance of ARFI in long-term outcome prediction among different etiologies of chronic liver *** Consecutive patients who received an ARFI study between 2011 and 2018 were *** excluding dual infection,alcoholism,autoimmune hepatitis,and others with incomplete data,this retrospective cohort were divided into hepatitis B(HBV,n=1064),hepatitis C(HCV,n=507),and non-HBV,non-HCV(NBNC,n=391)*** indexed cases were linked to cancer registration(1987-2020)and national mortality *** differences in morbidity and mortality among the groups were *** At the enrollment,the HBV group showed more males(77.5%),a higher prevalence of prediagnosed hepatocellular carcinoma(HCC),and a lower prevalence of comorbidities than the other groups(P<0.001).The HCV group was older and had a lower platelet count and higher ARFI score than the other groups(P<0.001).The NBNC group showed a higher body mass index and platelet count,a higher prevalence of pre-diagnosed non-HCC cancers(P<0.001),especially breast cancer,and a lower prevalence of *** gender,ARFI score,and HBV were independent predictors of *** 5-year risk of HCC was 5.9%and 9.8%for those ARFI-graded with severe fibrosis and *** alone had an area under the receiver operating characteristic curve(AUROC)of 0.742 for prediction of HCC in 5 *** increased to 0.828 after adding etiology,gender,age,and platelet *** difference was found in mortality rate among the *** The HBV group showed a higher prevalence of HCC but lower comorbidity that made mortality similar among the *** patients with ARFI-graded severe fibrosis or cirrhosis should receive regular surveillance.

关键词： Non-alcoholic fatty liver disease Hepatitis B Hepatocellular carcinoma Acoustic radiation force impulse Mortality Comorbidity

Hydrocarbon pneumonitis following fuel siphonage: A case report and literature review

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World Journal of Emergency Medicine 2019年第2期10卷 69-74页

作者： Yi-jung Chen Chien-chin hsu Kuo-tai Chen Emergency Department Chi-Mei Medical Center Department of Biotechnology Southern Tainan University of Technology Department of Emergency Medicine School of Medicine College of Medicine Taipei Medical University

BACKGROUND: People sometimes siphon fuel to fill their tanks. However, this is a potentially dangerous procedure and may cause hydrocarbon pneumonitis. We present the case of a patient with severe hydrocarbon pneumonitis after siphoning fuel. The patient underwent artifi cial ventilation and was admitted to hospital for 97 days. METHODS: We review the relevant literature for a better understanding of clinical features and management strategies for hydrocarbon pneumonitis following fuel ***: We reviewed 15 articles, which included 3 original articles and 12 case reports that reported the clinical features of fuel siphonage. In addition, we added our presented case for data analysis. A total of 40 cases were included in this review. The literature review found that hydrocarbon pneumonitis caused by fuel siphonage occurs worldwide and that most patients(80%) became symptomatic within 1 day of aspiration. Cough(70%), chest pain(62.5%), dyspnoea(55%), and fever(52.5%) presented in more than half of all patients. The right middle lobe(80%) was the predominantly involved lung fi eld; more than one-third of patients(36.7%) showed the involvement of two ***: Patient history, computed tomographic scans of the chest, and bronchoalveolar lavage are the commonly used diagnostic tools. Supportive care remains the foundation of treatment, whereas antibiotics, steroids, and bronchoalveolar lavage are practical therapies. Patients' clinical improvement precedes the resolution of lesions on chest X-ray. Most complications arise from pulmonary lesions. The prognosis of patients suffering from hydrocarbon pneumonitis following fuel siphonage might be improved by accurate diagnosis and appropriate care.

关键词： Siphonage Diesel Fuel Aspiration Hydrocarbon pneumonitis