http://scholars.ntou.edu.tw/handle/123456789/191 Sat, 25 Apr 2026 13:36:34 GMT 2026-04-25T13:36:34Z http://scholars.ntou.edu.tw:80/retrieve/73/海洋工程科技學士學位學程(系).png http://scholars.ntou.edu.tw/handle/123456789/191 http://scholars.ntou.edu.tw/handle/123456789/26543 標題: Hydrodynamic performance of a viscoelastic flexible membrane floating over a submerged rubble mound breakwater under oblique wave incidence 作者: Swami, Kailash Chand; Koley, Santanu; Tsai, Chia-Cheng 摘要: This study investigates the scattering of oblique water waves by a viscoelastic membrane placed over a trapezoidal rubble-mound breakwater on a sloped seabed. This study considers both wave scattering and trapping when a partially reflecting seawall is positioned downstream. The boundary value problem related to the present physical setup is solved using the hybrid boundary element method-based approach by coupling the central difference scheme with the boundary element method (BEM) to handle the second-order dynamic boundary condition of the viscoelastic floating flexible membrane. The flow through the rubble mound porous breakwater is modeled using the Sollitt and Cross ["Wave transmission through permeable breakwaters," in Coastal Engineering (ASCE, 1972), pp. 1827-1846] model, while the flow through the flexible floating viscoelastic membrane is described based on the formulation presented by Agarwal et al. [J. Fluids Struct. 129, 104167 (2024)]. According to the given model, the transmitted energy is below 30% for moderate values of the viscoelastic damping parameter of the membrane. The moderate values of the breakwater's porosity and structural size are suitable for optimal performance of the present configuration of the viscoelastic membrane-breakwater setup. Also, the wave run-up coefficient, reflected energy, and wave force acting on the partially reflecting seawall show an oscillatory pattern for numerous values of seawall coefficient and inclination angle when plotted as a function of relative spacing between the breakwater and seawall. A rubble-mound breakwater combined with a viscoelastic flexible membrane effectively reduces wave energy, creating a calmer lee side zone. Fri, 01 Aug 2025 00:00:00 GMT http://scholars.ntou.edu.tw/handle/123456789/26543 2025-08-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26540 標題: Modeling an array of surface-piercing piezoelectric plate wave energy converters for wave power absorption 作者: Sarkar, Biman; De, Soumen; Tsai, Chia-Cheng; Hsu, Tai-Wen 摘要: In recent years, the pursuit of sustainable ocean energy has accelerated, with wave energy conversion technologies emerging as a promising avenue for low-power electricity generation. Among various approaches, extracting electrical energy from ocean waves through piezoelectric mechanisms offers an innovative and eco-friendly solution. Acting as flexible plate-type wave energy converters, these structures are designed to efficiently capture the hydrodynamic energy of surface waves. The primary motivation behind this work arises from the observation that surface-piercing, vertically oriented piezoelectric plate-type wave energy converters have not been reported in the existing literature, to the best of the authors' knowledge. Despite their significant potential for practical marine energy applications, vertical piezoelectric configurations can provide advantages in achieving the optimum electrical load resistance, thereby maximizing harvested power, compared to horizontally oriented configurations (Kazemi et al., 2021). To overcome the mathematical complexities associated with the coupling between structural flexibility and piezoelectric interactions, a rigorous semi-analytical framework is developed. These complexities arise due to boundary conditions that involve higher-order derivatives with complex-valued coefficients. The governing problem is reformulated into a set of coupled integral equations by employing Green's function solutions along with mixed Fourier transform techniques. These equations are subsequently solved through a Singularity-Respecting Galerkin approximation, yielding accurate evaluations of the hydrodynamic response, including the reflection characteristics, wave power absorption efficiency and hydrodynamic wave forces. Furthermore, a comprehensive parametric investigation is undertaken to elucidate the influences of wave and structural parameters on plate deflection, bending moments and shear forces. Deploying multiple piezoelectric plates in an array has been found to be a more promising approach for wave power absorption. Widening the spacing between adjacent plates greatly influences the deflection of the leeward plate, regardless of whether the edges are clamped-clamped or clamped-free. The outcomes offer valuable physical insights into the energy extraction capability and dynamic behavior of the proposed array of surface-piercing piezoelectric plate-type wave energy converters. Thu, 01 Jan 2026 00:00:00 GMT http://scholars.ntou.edu.tw/handle/123456789/26540 2026-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26523 標題: Integral and Numerical Formulations for Seeking the Period of Non-Conservative Nonlinear Oscillator With/Without the First Integral 作者: Liu, Chein-Shan; Tsai, Chia-Cheng; Chang, Chih-Wen 摘要: For a non-conservative nonlinear oscillator (NCNO) having a periodic solution, the existence of the first integral is a certain symmetry of the nonlinear dynamical system, which signifies the balance of kinetic energy and potential energy. A first-order nonlinear ordinary differential equation (ODE) is used to derive the first integral, which, equipped with a right-end boundary condition, can determine an implicit potential function for computing the period by an exact integral formula. However, the integrand is singular, which renders a less accurate value of the period. A generalized integral conservation law endowed with a weight function is constructed, which is proved to be equivalent to the exact integral formula. Minimizing the error to satisfy the periodicity conditions, the optimal initial value of the weight function is determined. Two non-iterative methods are developed by integrating three first-order ODEs or two first-order ODEs to compute the period. Very accurate value of the period can be observed upon testing five examples. For the NCNO without having the first integral, the integral-type period formula is derived. Four examples belong to the Li & eacute;nard equation, involving the van der Pol equation, are evaluated by the proposed iterative method to determine the oscillatory amplitude and period. For the case with one or more limit cycles, the amplitude and period can be estimated very accurately. For the NCNO of a broad type with or without having the first integral, the present paper features a solid theoretical foundation and contributes integral-type formulations for the determination of the oscillatory period. The development of new numerical algorithms and extensive validation across a diverse set of examples is given. Wed, 01 Jan 2025 00:00:00 GMT http://scholars.ntou.edu.tw/handle/123456789/26523 2025-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26507 標題: Hydrodynamic performance of a viscoelastic flexible membrane floating over a submerged rubble mound breakwater under oblique wave incidence 作者: Swami, Kailash Chand; Koley, Santanu; Tsai, Chia-Cheng 摘要: This study investigates the scattering of oblique water waves by a viscoelastic membrane placed over a trapezoidal rubble-mound breakwater on a sloped seabed. This study considers both wave scattering and trapping when a partially reflecting seawall is positioned downstream. The boundary value problem related to the present physical setup is solved using the hybrid boundary element method-based approach by coupling the central difference scheme with the boundary element method (BEM) to handle the second-order dynamic boundary condition of the viscoelastic floating flexible membrane. The flow through the rubble mound porous breakwater is modeled using the Sollitt and Cross [Wave transmission through permeable breakwaters Wed, 01 Jan 2025 00:00:00 GMT http://scholars.ntou.edu.tw/handle/123456789/26507 2025-01-01T00:00:00Z