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This study applies the unit tsunami method and probabilistic tsunami hazard analysis to investigate the tsunami hazard for the southern region of Pingtung County in southern Taiwan. The FUNWAVE-TVD model is used to calculate the aleatory and epistemic uncertainties. The aleatory uncertainty is analyzed using a comparison of simulated and observed maximum tsunami wave heights and the epistemic uncertainty is evaluated using a scenario caused by earthquakes in the Manila and Ryukyu subduction zones according to probabilistic seismic hazard analysis in Taiwan using Senior Seismic Hazard Analysis Committee Level 3 methodology. A unit tsunami method database is established for the Manila and Ryukyu subduction zones and used to carry out a probability-based offshore tsunami wave height simulation for the southern region of Pingtung County. A hazard map for tsunamis caused by earthquakes in the Manila and Ryukyu subduction zones is also derived.

Introduction: Syncope was reported to be associated with sudden cardiac death in heart failure patients regardless of the etiology of syncope. We attempted to use unsupervised machine learning to identify the prognostically distinct phenotypes in a large population of heart failure patients presenting with syncope. Hypothesis: Unsupervised machine learning can identify prognostically distinct phenotypes in a large population of heart failure patients presenting with syncope. Methods: Patients with a diagnosis of systolic or diastolic heart failure and syncope at Mayo Clinic sites were identified for baseline and follow-up data. Variables with ≥ 20% missing data were excluded; a total of 57 variables were used for k-means clustering analysis. Patients were grouped according to 4 distinct k-means determined clusters for statistical analysis. Results: A total of 3,557 patients with proper follow-up and echocardiography data were included in the final analysis. The median follow-up duration was 36.3 months, and 2908 (81.7%) patients died. Cluster 2 (n= 680) was identified as the cluster with the highest mortality (92%), which contained patients with high proportions of cardiovascular comorbidities, especially chronic kidney disease. The Kaplan-Meier survival curves are shown in Figure 1. In multivariate Cox regression analysis, the presence of CKD independently predicts mortality (HR 1.62, 95%CI 1.50-1.76, p Conclusions: Unsupervised machine learning identified patients with CKD, CAD and DM are high-risk phenotypes in heart failure patients with syncope, and can be used to guide future studies in this highly heterogeneous, unexplored population.

Introduction: Unsupervised machine learning (ML) can provide insight into a dataset without significant expert time for annotation and labeling, but was never used to assess the heterogeneous MitraClip population. Hypothesis: We hypothesized that unsupervised k-means ML could identify prognostically-distinct phenogroups in MitraClip patients without a priori knowledge of the dataset. Methods: Patients who underwent MitraClip (June 2014-September 2020) at Mayo Clinic sites were identified from the Mayo institutional NCDR database for baseline and follow-up data. Variables with ≥ 50% missing data were excluded. A k-means algorithm was used for clustering analysis. Input variables were grouped according to 4 distinct k-means determined clusters. Kaplan-Meier survival analysis was used to assess the survival of each cluster. Results: A total of 389 consecutive patients were included in the final analysis, and 95 unique variables were used. The mean age was 80.3±8.7 years; 256 (65.8%) were male. The mean STS MV Replace score was 9.1±5.7. Fifty-five (14.5%) patients died during the mean follow duration (185 days). Kaplan-Meier analysis showed significant survival differences among clusters (Figure 1). The cluster (cluster 2, n=120) with best survival performance (all-cause mortality 3.3%) had features of non-calcified mitral leaflets, nonischemic cardiomyopathy, and less than moderate tricuspid regurgitation. Cluster 3 (n=66) had the worst survival performance (all-cause mortality 27.3%) and opposite features than cluster 2. Conclusions: Unsupervised ML can identify distinct phenotype clusters with prognostic significance in MitraClip patients. Patients with non-calcified mitral leaflets, nonischemic cardiomyopathy, and less than moderate tricuspid regurgitation are intrinsically different from other MitraClip patients and should be considered the potential optimal candidates.

Introduction: Multiple supervised machine learning (ML) models have been used to assess the outcomes in patients who underwent transcatheter aortic valve replacement (TAVR) procedure, however, supervised ML requires significant expert time for annotation and labeling. Unsupervised ML can provide insight into the dataset without this process. Hypothesis: We hypothesized that unsupervised k-means ML can identify distinct phenogroups in TAVR patients that can predict prognosis without a priori knowledge. Methods: A retrospective study of patients who underwent TAVR (Jan 2012-Dec 2017) at Mayo Clinic sites was performed. Baseline demographics, EKG, cardiac computed tomography, and echocardiographic data were abstracted. Variables with ≥ 20% missing data were excluded. Prior to the k-means clustering algorithm, principal component analysis was used for dimensionality reduction. Input variables were analyzed according to k-means determined clusters. Kaplan-Meier survival analysis was used to assess the survival of each cluster. Results: A total of 1071 consecutive patients were included in the final analysis. A total of 141 unique variables were used. The mean age was 80.7±8.6 years, 58.2% were male. Patients were divided into 2 distinct phenogroups. In the two phenogroups, cluster 0 (n=639) has significantly better survival than cluster 1 (n= 432) (log-rank p=0.0002) (Figure 1). Cluster 1 has features of low flow-low gradient (LFLG) hemodynamic profile, including lower systolic blood pressure, mean aortic valve gradient, peak aortic valve velocity, and worse LV ejection fraction. Conclusions: Unsupervised ML can identify distinct phenotype features with prognostic significance in TAVR patients. Our results suggest that patients with LFLG hemodynamic features are intrinsically different from other TAVR patients and require more attention to avoid adverse outcomes.

The ocean surface waves during Super Typhoons Maria (2018), Lekima (2019), and Meranti (2016) were reproduced using hybrid typhoon winds and a fully coupled wave-tide-circulation modeling system (SCHISM-WWM-III). The hindcasted significant wave heights are in good agreement with the along-track significant wave heights measured by the altimeters aboard the SARAL (Satellite with ARgos and ALtiKa) and Jason-2 satellites. Two numerical experiments pairing Super Typhoons Maria (2018) and Meranti (2016) and Super Typhoons Lekima (2019) and Meranti (2016) were conducted to analyze the storm wave characteristics of binary and individual typhoons. Four points located near the tracks of the three super typhoons were selected to elucidate the effects of binary typhoons on ocean surface waves. The comparisons indicate that binary typhoons not only cause an increase in the significant wave height simulations at four selected pints but also result in increases in the one-dimensional wave energy and two-dimensional directional wave spectra. Our results also reveal that the effects of binary typhoons on ocean surface waves are more significant at the periphery of the typhoon than near the center of the typhoon. The interactions between waves generated by Super Typhoons Maria (2018) and Meranti (2016) or Super Typhoons Lekima (2019) and Meranti (2016) might be diminished by Taiwan Island even if the separation distance between two typhoons is

While land subsidence (LS) caused by groundwater overuse is a significant contributor to inundation in coastal areas, rising sea levels remain the critical factor affecting coastal flooding globally. In this work, we projected potential inundation areas on the midwestern coast of Taiwan in 2100 using a high-resolution numerical model with light detection and ranging (LiDAR)-based digital elevation data. Two simulation approaches, namely, constant spring tide (CST) and dynamic astronomical tide (DAT) approaches, were employed to pair various sea-level rise (SLR) magnitudes from the 6th Assessment Report of IPCC with LS magnitudes reported by the Water Resource Agency of Taiwan. The CST method always projected larger maximum inundation areas (MIAs) than the DAT method. However, the discrepancies in the MIA projections between the CST and DAT methods showed exponential decay as the SLR magnitude increased. Through 1320 scenario simulations, the projected worst-case median MIAs derived using the CST and DAT methods were approximately 1100 and 1000 km2 in the year 2100, respectively, and the synergistic effect of SLR and LS significantly exacerbated the coastal inundation. This study indicates that the DAT approach is more realistic than the CST approach for modelling actual tidal variations and is suitable for assessing coastal inundation due to rising sea levels and subsiding lands worldwide.

In this study, long-term wind fields during 1991–2010 from the Climate Forecast System Reanalysis (CFSR) were dynamically downscaled over Taiwan and its offshore islands at a 5 km horizontal resolution using the Weather Research and Forecasting (WRF) model. Simulations of the 10 m (above sea level) dynamically downscaled winds served as the atmospheric forcing for driving a fully coupled wave-circulation model. The sea states of the waters surrounding Taiwan during 1991–2010 were hindcasted to evaluate the offshore wave energy resources and optimal wave energy hotspots. This study reveals that the southeastern offshore waters of Taiwan and the Central Taiwan Strait exhibited the highest mean wave power density (WPD), exceeding 20 kW/m. The annual mean WPD, incidence of the hourly WPD greater than or equal to 4 kW/m, monthly variability index and coefficient of variation of the WPD indicated that the sea areas located between Green Island and Orchid Island (OH_1), southeast of Orchid Island (OH_2), south of the Hengchun Peninsula (OH_3), and north of the Penghu Islands (OH_4) were the optimal hotspots for deploying wave energy converters. The most energetic months were October for OH_1 and OH_2 and November for OH_3 and OH_4, while the wave power was weak from March to June for OH_1, OH_2 and OH_3 and in May for OH_4. The wave direction is prevailingly east-northeast for OH_1, OH_2 and OH_3 and nearly northeast for OH_4. These phenomena reveal that wave power in the waters offshore Taiwan is induced primarily by the northeast (winter) monsoon. The exploitable annual WPD was estimated to be 158.06, 182.89, 196.39 and 101.33 MWh/m for OH_1, OH_2, OH_3 and OH_4, respectively.

This study explores coastal hazard characteristics along Provincial Highway No. 9 (hereafter the Provincial Highway) in Taiwan. Numerical simulation was conducted to analyze wave attacks and medium-to-long-term coastal morphological change along the Provincial Highway and identify areas of high hazard potential. Hydrodynamic and morphological change numerical models were used to simulate various meteorological scenarios in the research site, specifically, far-field, medium-field, and near-field simulations were performed. Subsequently, the simulated results were employed to analyze hazard characteristics and determine the potential for hazard along the Provincial Highway. According to the analysis of hazard characteristics, the high potential of wave attacks was revealed in the following sections of the highway: 440K+000-441K+000, areas near 424K+500, and 396K+000-396K+500, and the highest potential for erosion was shown in the areas near 418K+000 and 397K+500. Finally, these areas with a high potential for wave attacks and erosion were marked to create a map of hazard potential for the provincial highway, and thus provide insights into future construction works or hazard-prevention operations.

The sensitivity of storm wave simulations to storm tides and tidal currents was investigated using a high-resolution, unstructured-grid, coupled circulation-wave model (Semi-implicit Cross-scale Hydroscience Integrated System Model Wind Wave Model version III (SCHISM-WWM-III)) driven by two typhoon events (Typhoons Soudelor and Megi) impacting the northeastern coast of Taiwan. Hourly wind fields were acquired from a fifth-generation global atmospheric reanalysis (ERA5) and were used as meteorological conditions for the circulation-wave model after direct modification (MERA5). The large typhoon-induced waves derived from SCHISM-WWM-III were significantly improved with the MERA5 winds, and the peak wave height was increased by 1.0&ndash, 2.0 m. A series of numerical experiments were conducted with SCHISM-WWM-II and MERA5 to explore the responses of typhoon wave simulations to tidal elevation and current. The results demonstrate that the simulated significant wave height, mean wave period and wave direction for a wave buoy in the outer region of the typhoon are more sensitive to the tidal current but less sensitive to the tidal elevation than those for a wave buoy moored in the inner region of the typhoon. This study suggests that the inclusion of the tidal current and elevation could be more important for typhoon wave modeling in sea areas with larger tidal ranges and higher tidal currents. Additionally, the suitable modification of the typhoon winds from a global atmospheric reanalysis is necessary for the accurate simulation of storm waves over the entire region of a typhoon.

Wu, E.C.; Chen, Y.L.; Wu, H.L.; Hu, K.C.; Hsiao, S.C., and Wu, Y.C., 2018. Incorporating Tidal Uncertainty into the Methodology of Probabilistic Tsunami Hazard Analysis. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 691–695. Coconut Creek (Florida), ISSN 0749-0208.The Circum-Pacific Belt has become active in recent years, and the earthquake in the border area of land and sea probably causes tsunami disaster. The hazard includes overflow flooded, building damage, casualties, and radiation crisis of nuclear power plant. To quantify the risk, probabilistic tsunami hazard analysis (PTHA) serves as a robust methodology. The uncertainty stemming from the deviation of modeling, named aleatory uncertainty, is considered with including the tidal effect on the tsunami. To deal with the aleatory uncertainty, we incorporate tidal uncertainty into PTHA. Different static tidal stages are set in Cornell Multi-grid Coupled Tsunami model (COMCOT) to evaluate tsunami hazards. Three kinds of method are presented. One could apply theoretical probability distribution to different maximum wave height by the Gaussian Method. On the other hand, the Δt method and the Pattern Method combine tsunami events with a typical year of tidal record. The difference between these methods are discussed, and the Pattern Method is regarded as the most rigorous way. Finally, the method of incorporating tidal uncertainty into PTHA has been established and been utilized to Maanshan nuclear power plant in Taiwan.

Under climate change, compound flooding has resulted in severe disasters in coastal areas around the world. In this study, an integrated framework is proposed to determine the range of compound flood risk without the requirement of joint probability analysis between storm surge and rainfall. In the framework, the flood risks are analyzed under four extreme scenarios with/without the compound effect of storm surge and rainfall in the past and the future. From the end of the 20th century to the middle of the 21st century, the worst scenario shows that the flood area significantly increases by 92% for the low-lying coastal areas in southwest Taiwan under the compound effect of storm surge and rainfall if they are fully correlated. In the most optimistic scenario, the flood area slightly increases by 15% without compound effect (only storm surge is considered). To coastal flooding, the synchronization of storm surge and rainfall contributes much more than the climate-induced amplification of individual factors. When storm surge and rainfall happen at the same time, the extent and duration of flooding increase simultaneously under the influence of pluvial and surge-induced flooding. Risk analysis shows an obvious increase of risk level for villages originally at low risks, which require integrated countermeasures against the consequence brought by compound flooding in the future. The framework can be applied in other low-lying coastal areas to quantify the potential impacts on human and environment caused by compound flooding under climate change.

Wu, E.C.; Ma, W.H., Chen, Y.L.; Wu, H.L.; Hu, K.C.; Hsiao, S.C. and Wu, Y.C., 2016. Probabilistic Tsunami Hazard Analysis — Application to Maanshan Nuclear Power Plant in Taiwan. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1267 - 1271. Coconut Creek (Florida), ISSN 0749-0208. In the past twelve years, two earthquakes of magnitude 9.0 have occurred in the western Pacific. These earthquakes resulted in tsunamis, causing tremendous casualties, such as the nuclear disaster in Japan on March, 2011. Taiwan is an island located in the circum-Pacific belt, along which approximately 90% of the world's largest earthquakes take place. To prevent hazards, probabilistic tsunami hazard analysis (PTHA) is applied to nuclear power plants in the coastal regions of Taiwan. The approach developed here allows for the selection of reasonable tsunamis gene...

In this study a mesh-free numerical model for simulating 3-D free-surface potential flows is established. A time-marching scheme in Lagrangian aspect is chosen for the specification of boundary conditions on the moving and deforming free surface while a local polynomial collocation method is applied for solving the Laplace equation at each time step. This collocation method is employed because the partial derivatives of the solution are calculated accurately. The trajectory of each free-surface node can thus be predicted precisely due to the accurate estimation of the partial derivatives of velocity potential, which represent components of the velocity vector at that specific node. The numerical model is applied to the simulation of free surface waves by the liquid sloshing in rectangular, square and cylindrical swaying tanks. Fairly good agreements are observed in the comparison of numerical results with experimental data. Because the partial derivatives of the velocity components are accurately calculated, the pressure distribution in the domain can also be acquired by solving the pressure Poisson equation separately.

The induced density-stratified fluid motion of a solitary wave propagating over a submarine trench was investigated numerically and experimentally. A new laboratory experiment in a two-dimensional wave flume on dense fluid transport and flow fields inside and around the trench was reported using a measurement framework of laser-induced fluorescence (LIF) and particle image velocimetry (PIV) techniques. A 3D Navier–Stokes numerical model was applied to trace the dense fluid transport using the volume of fluid method. Good agreements were obtained between experiments and computed results. The calibrated model was then used to examine the transport processes of the various dense fluids. Particular attention is paid to the evolution of vortices induced by solitary waves. The results indicate that transported height of dense fluid around the windward trench wall decreases when the dense fluid density increases or wave nonlinearity decreases. The dense fluid is allowed to be transported toward the upstream of the trench when a denser fluid or lower wave nonlinearity is considered. The presence of strong vortical structure and vorticity strength was observed as the dense fluid density decreases or wave nonlinearity increases. Quantitative analyses also demonstrate that either density of dense fluid or wave nonlinearity significantly affects the transport process of the dense fluid.

Interfacial waves under various wave conditions are numerically and experimentally investigated within a submarine rectangular trench. The three-dimensional numerical model Truchas is employed to trace the free surface and the interfacial motion using the volume of fluid method. The free surface and interfacial motion are measured using a CCD camera to validate the model. Both the numerical and experimental results show two types of interfacial motion, namely, partial standing wave patterns and traveling wave patterns. The numerical model is then employed to study the mechanisms of the different modes of interfacial motions (partial standing/traveling waves) and their corresponding amplification factors (external/internal modes). It is shown that the partial standing wave patterns are easily generated when the motion of the surface waves is 180° out of phase at the two sides of the trench. However, the existence of partial standing wave patterns does not mean partial standing internal waves occur. The partial standing internal waves are triggered as internal wave wavelengths reach resonant condition. Furthermore, the ratio of the interface wave height to the surface wave height decreases with wave nonlinearity, suggesting that the nonlinear effect may significantly change the interfacial wave motion. Finally, it is found that the excited pairs of counter-rotating vortices around the interfacial wave can induce a large velocity in the lower layer for the internal mode, indicating that bottom erosion can be enhanced in this manner.

A two-dimensional numerical model in OpenFOAM, an open-source computational fluid dynamics software package, is used to investigate Bragg resonance under a wave-current field. An internal mass source wavemaker and a numerical sponge layer are implemented for wave-current generation and wave absorption, respectively. To ensure the validity of the internal wavemaker, a series of examinations is carried out. A simulation of wave-current interaction with a sinusoidal bottom is then carried out. The numerical results are compared with available experimental data and theoretical results. Moreover, the reflectivity and flow field in the presence of uniform and shear currents are investigated.