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Articles 1 - 30 of 55
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A Simplified Two-Switching-Based Model-Free Predictive Current Controller For An Interior Permanent Magnet Synchronous Motor Drive System, Cheng-Kai Lin, Jen-Te Yu, Jyun-Ting Wang, Yen-Shin Lai, Hsing-Cheng Yu, Hao-Qun Huang
A Simplified Two-Switching-Based Model-Free Predictive Current Controller For An Interior Permanent Magnet Synchronous Motor Drive System, Cheng-Kai Lin, Jen-Te Yu, Jyun-Ting Wang, Yen-Shin Lai, Hsing-Cheng Yu, Hao-Qun Huang
Journal of Marine Science and Technology
This paper presents a simplified two-switching-based modelfree predictive current control (STSB-MFPCC) method as well as its application to interior permanent magnet synchronous motor (IPMSM) drive systems. Unlike existing model predictive current controller (MPCC) that uses 7 basic voltage vectors, STSB-MFPCC employs 19 synthesized ones, with each of which consisting of two basic voltage vectors. The new method does not require any information about the load parameters, back electromotive force, nor the system model. Compared to modelbased controllers, the proposed one has a distinctive and appealing nature in that it is much less sensitive to system parameter variations. A digital signal …
Collision Avoidance Path Planning For Ships By Particle Swarm Optimization, Yu-Tao Kang, Wei-Jiong Chen, Da-Qi Zhu, Jin-Hui Wang, Qi-Miao Xie
Collision Avoidance Path Planning For Ships By Particle Swarm Optimization, Yu-Tao Kang, Wei-Jiong Chen, Da-Qi Zhu, Jin-Hui Wang, Qi-Miao Xie
Journal of Marine Science and Technology
Ship collision avoidance is a key consideration in maritime systems. Collision avoidance maneuvers depend on navigators’ experience and skill levels. Because both maritime traffic densities and average ship speeds are increasing, the times available for decision-making are decreasing, which elevates the risk of human errors in the collision avoidance process. To reduce the effect of human factors and efficiently prevent collisions between ships navigating in open water with effective visibility, a particle swarm optimization (PSO) algorithm can be used to plan ship paths. An improved ship domain dynamic model can assess collision risks in close-range encounters. Several marine traffic scenarios …
Hydrodynamic Analysis Of Underwater Glider With Diamond Wing In Unsteady And Nonuniform Flow Field, Chen-Wei Chen, Zhuo Feng, Xu Liang
Hydrodynamic Analysis Of Underwater Glider With Diamond Wing In Unsteady And Nonuniform Flow Field, Chen-Wei Chen, Zhuo Feng, Xu Liang
Journal of Marine Science and Technology
In this study, the hydrodynamic performance of a proposed underwater glider (UG) that utilizes a diamond wing was analyzed and its gliding ability in undersea environments with both steady and uniform and unsteady and nonuniform oceanic currents optimized. The flow field around the UG was analyzed using the software package RANS CFD. Under conditions where the current varied linearly both with water depth and time, the UG exhibited harmonically heaving and pitching motions, with a constant acceleration incident flow. The dynamic lifting and drag forces acting on the diamond wing and the dynamic heaving force and pitching moment acting at …
Parametric Design And Optimization Of A Pivoting S-Type Rudder For Containerships, Chen-Wei Chen, Tsung-Yueh Lin, Bo-Yen Chen, Jen-Shiang Kouh
Parametric Design And Optimization Of A Pivoting S-Type Rudder For Containerships, Chen-Wei Chen, Tsung-Yueh Lin, Bo-Yen Chen, Jen-Shiang Kouh
Journal of Marine Science and Technology
This study proposes an energy-saving S-type rudder design to deal with the inhomogeneous inflow from a rotating propeller behind a containership. The S-type rudder was modelled parametrically using four-digit NACA foils as section profiles together with Non-uniform rational B-splines (NURBS) surface formulations. A three-stage optimization process is proposed to reduce the number of design iterations necessary to achieve an optimal design. The propulsion simulations were done via CFD software, which solves the hydrodynamics of viscous flow, as governed by the Reynold-averaged Navier-Stokes (RANS) equations. Validations were performed with experimental model tests, including hull resistance, propeller open-water performance, and propulsion in …
Fast Forward-Backward Channel Estimation For Mimo Stbc-Ofdm Systems, Lena Chang
Fast Forward-Backward Channel Estimation For Mimo Stbc-Ofdm Systems, Lena Chang
Journal of Marine Science and Technology
In the study, we develop a fast forward-backward estimation (FFBE) method for multiple input multiple output (MIMO) space time block code (STBC) orthogonal frequency division multiplexing (OFDM) systems. We examined the matrix structure of the forward-backward (FB) correlation matrix and observed this matrix possessing permutation invariant (PI) property. We also investigated the eigen-property of a matrix with PI property and proved its eigenvectors possessing symmetric property, which can be calculated from two half dimensionality submatrices. Based on these analyses, we propose a fast eigen-decomposition algorithm to reduce the computations required in the eigendecomposition of FB correlation matrix. Then, the symmetric …
Vortex Motions Around A Vertically Vibrating Cylinder In Oscillatory Flows, Symphony Chakraborty, Tzu-Wen Lin, Ming-Jyh Chern
Vortex Motions Around A Vertically Vibrating Cylinder In Oscillatory Flows, Symphony Chakraborty, Tzu-Wen Lin, Ming-Jyh Chern
Journal of Marine Science and Technology
Numerical simulations of the vortex-induced vibration (VIV) on a circular cylinder in an oscillatory flow were conducted using the direct-forcing immersed boundary (DFIB) method. VIV of structures is a practical engineering problem. Many engineers have devoted themselves to research on the prevention of VIV, which can cause severe damage to offshore construction equipment and structures. Fluctuating hydrodynamic force induces vibration of structures because of the vortex around the structure. This vibration causes structural failure due to the lock-in phenomenon. A phenomenon termed “springing” (a secondorder wave effect caused by superposition of the incident waves and the reflected waves or other …
Brand Loyalty In The Cruise Sector: Age Cohorts, Gender, And Travel Attributes As Key Moderators For Relationship Marketing Theory, Stephen Wen-Hung Wang, Maxwell Kuo-Hsuan Hsu, Angeline Close Scheinbaum, Feng-Ming Tsai
Brand Loyalty In The Cruise Sector: Age Cohorts, Gender, And Travel Attributes As Key Moderators For Relationship Marketing Theory, Stephen Wen-Hung Wang, Maxwell Kuo-Hsuan Hsu, Angeline Close Scheinbaum, Feng-Ming Tsai
Journal of Marine Science and Technology
Testing established theory in relationship marketing, we examine the impact of customer relationship management on customer satisfaction and brand loyalty in the context of the cruise industry. Individual differences such as age cohort (e.g., millennials, Gen X, baby boomers), gender, and consumers’ desired travel attributes are examined as moderators. Cruise vacation consumers at an international cruise harbor were approached to complete an in-person survey (n = 226). Empirical findings support extant theory in relationship marketing in that consumers’ perception of relationship investment raises satisfaction and, in turn, brand loyalty. Notably, when customer relationship investment is degenerated into a second order …
Analysis Of Fuel Cell Applied For Submarine Air Independent Propulsion (Aip) System, Jen-Chieh Lee, Tony Shay
Analysis Of Fuel Cell Applied For Submarine Air Independent Propulsion (Aip) System, Jen-Chieh Lee, Tony Shay
Journal of Marine Science and Technology
In this paper, the performance of a 2000-ton hybrid AIP system submarine is investigated by analyzing the weight, volume and efficiency of its propulsion system. The engine of the investigated AIP system employs a low temperature polymer electrolyte membrane fuel cell which makes use of the hydrogen and oxygen as the reactants. More specifically, the reactants of fuel cell in this study are considered from the combination of three fuel storage systems, methanol (MeOH), liquid hydrogen (LH2) and metal hydride (MH2), and two oxidant storage systems, liquid oxygen (LOX) and compressed oxygen (O2). Based on the assumed various daily propulsion …
An Experimental And Numerical Study Of A High Speed Planing Craft With Full-Scale Validation, Ahmet Gultekin Avci, Baris Barlas
An Experimental And Numerical Study Of A High Speed Planing Craft With Full-Scale Validation, Ahmet Gultekin Avci, Baris Barlas
Journal of Marine Science and Technology
During the conceptual design of a high speed craft, the most important element of the process is resistance and drag prediction. To increase efficiency in high speed craft design, the prediction of total resistance must be increasingly accurate. To achieve this objective, model towing tank tests were used. Although testing will always be necessary, the growing field of computational fluid dynamics (CFD) is gaining interest, considering the experimental costs. This paper investigates both the experimental and numerical methods of total resistance prediction for a high speed hull, including comparison of the trim and sinkage measurements. Additionally, the model tests were …
Flow Characteristics And Velocity Fields Of Swirling Double-Concentric Jets At High Central Jet Reynolds Numbers, Minh Duc Le, Ching Min Hsu, Rong Fung Huang
Flow Characteristics And Velocity Fields Of Swirling Double-Concentric Jets At High Central Jet Reynolds Numbers, Minh Duc Le, Ching Min Hsu, Rong Fung Huang
Journal of Marine Science and Technology
The flow characteristics and velocity fields of swirling doubleconcentric jets at a high central jet Reynolds number were studied. The central jet Reynolds numbers varied from 700 < Rec < 1000. The flow behaviors of the swirling double-concentric jets were observed using a laser light sheet assisted by a smoke-wire flow visualization technique. The time-averaged velocity vectors and streamlines, normalized velocity contours, fluctuation intensity contours, and vorticity contours were carried out using particle image velocimeter (PIV). Two characteristic flow modes are classified: the central jet-dominated radial flow occurs at a low annular jet Reynolds number while the high-turbulence swirling wake appears at a high annular jet Reynolds number. The flow feature of the central jet-dominated radial flow presents a wideopen shear layer because of the effect of a high-speed deflected central jet. A large dual-ring vortex in the wake and two pairs of vortices in the gap between the control disk and primary disk in the high-turbulence swirling wake mode appear. The turbulence intensity in the high-turbulence swirling wake were significantly larger than those in the central jet-dominated radial flow.
Robust Control Of Discrete-Time Uncertain Stochastic Systems Subject To Mixed H2/Passivity Performance, Cheung-Chieh Ku, Rui-Wen Chen, Guan-Wei Chen, Wen-Jer Chang
Robust Control Of Discrete-Time Uncertain Stochastic Systems Subject To Mixed H2/Passivity Performance, Cheung-Chieh Ku, Rui-Wen Chen, Guan-Wei Chen, Wen-Jer Chang
Journal of Marine Science and Technology
This paper investigates a mixed H2/Passivity performance control problem of uncertain stochastic systems. Based on Itô stochastic equation, the considered system is described by a linear difference equation with multiplicative noise term. To minimize output energy and guarantee asymptotical stability, the H2 scheme is employed. Moreover, passivity theory is applied to constrain the effect of external disturbance on the system. According to the passivity theory, a general and flexible mixed performance controller design method is proposed. Based on Lyapunov function, some sufficient conditions are derived into extended Linear Matrix Inequality (LMI) form which reduces conservatism of finding the feasible solutions. …
Numerical Simulation And Experimental Validation Of The Vibration Suppression Control By Using Input Shaping Technique With Extended Kalman Filter, Yi-Cheng Huang, Yen-Lin Lee, Ming-You Ma
Numerical Simulation And Experimental Validation Of The Vibration Suppression Control By Using Input Shaping Technique With Extended Kalman Filter, Yi-Cheng Huang, Yen-Lin Lee, Ming-You Ma
Journal of Marine Science and Technology
The development of high-speed and high-precision machine tools is a challenge for designers because of the difficulties associated with the vibration control of mechanical systems. This study proposed a method to suppress such vibration by using input shaping functions with an extended Kalman filter (EKF). Input shaping is a technique that deploys one or several designed impulses to eliminate the vibration response of a mechanical system. To determine the parameters of an input shaper, the vibration of the mechanical system was assumed to be a simple, exponentially decaying sinusoidal signal. The EKF was used to estimate signal parameters, namely frequency …
Performance Analysis Of An Active Heave Compensation System On An Offshore Supply Vessel Using The Hardware-In-The-Loop Simulation, Luman Zhao, Myung-Il Roh
Performance Analysis Of An Active Heave Compensation System On An Offshore Supply Vessel Using The Hardware-In-The-Loop Simulation, Luman Zhao, Myung-Il Roh
Journal of Marine Science and Technology
The active heave compensation (AHC) system on an offshore supply vessel (OSV) plays a pivotal role in offshore installation operations by minimizing the heave motion of suspended subsea equipment, regardless of the OSV motion. In order to successfully perform its function, the AHC system should have a suitable control algorithm, and its performance must be evaluated in advance of operation. Performance analysis of the AHC system requires complicated testing procedures, and a great deal of associated equipment. In particular, such analysis is often very costly and time-consuming, and realistic conditions are typically impossible to establish in a testing environment. To …
Sound And Vibration Analysis Of A Marine Diesel Engine Via Reverse Engineering, Jinsiang Shaw, Yun-Hong Wang, Cherng-Yuan Lin
Sound And Vibration Analysis Of A Marine Diesel Engine Via Reverse Engineering, Jinsiang Shaw, Yun-Hong Wang, Cherng-Yuan Lin
Journal of Marine Science and Technology
In this study, a sound and vibration analysis of a marine diesel engine was conducted. The vibration and sound signals of the engine under various operating conditions were measured and analyzed by applying a spectrum analysis and an ordertracking analysis. In addition, a finite-element model of the engine was constructed via reverse engineering from a 3D scan. The main causes of engine vibration and noise were clarified and identified individually through the experiments and the engine model. Finally, the biodiesel-blended diesel fuel was used for the engine for comparing sound and vibration performance with the ultra-low sulfur diesel (ULSD). In …
Qualitative Survey Of A Coastal Region From A Polarimetric Analysis Of Synthetic Aperture Radar Images, Hsiu-Wen Wang, Hsuan Ren
Qualitative Survey Of A Coastal Region From A Polarimetric Analysis Of Synthetic Aperture Radar Images, Hsiu-Wen Wang, Hsuan Ren
Journal of Marine Science and Technology
This study applied a time series of fully polarimetric synthetic aperture radar (SAR) images using RADARSAT-2 to analyze the polarimetric responses of the west coast of Taiwan. A total of seven images were acquired from 2009 and 2012, covering the low, high, and similar tide levels. A four-component target decomposition algorithm was used to investigate the tidal effects and dynamic ocean interactions of sandbanks near the coast. The experimental results showed that the Yamaguchi fourcomponent decomposition can extract different features in the coastal area efficiently and effectively. From the target decomposition image constructed using the Yamaguchi four-component model, strong double-bounce …
A Novel Damaged Ship Righting Plan Optimization Method Based On Artificial Bee Colony Algorithm, Kai Li, Zhijiang Yuan, Xiaogang Jiang
A Novel Damaged Ship Righting Plan Optimization Method Based On Artificial Bee Colony Algorithm, Kai Li, Zhijiang Yuan, Xiaogang Jiang
Journal of Marine Science and Technology
With the increase of the sea disaster caused by ship capsizing, self-rescuing ability of damaged ship has attracted much attention among ship designers, ship owners, classification societies and authorities. Damaged ship righting optimization remains a very complicated problem due to the feasible combinations of counter-flooding approaches with different compartments and loads are numerous. The effectiveness and efficiency of the artificial bee colony (ABC) algorithm has been demonstrated on the combinatorial optimization problem. In this paper, an ABC algorithm-based righting plan optimization method for damaged ship is proposed. In this method, the objective is to minimize the inclination angle under a …
Changing Flow Capacity In The Upper Yellow River By Using A Standardized Dike, Tao Bai, Jian Wei, Rong Ma, Chuan-Hui Ma, Qiang Huang
Changing Flow Capacity In The Upper Yellow River By Using A Standardized Dike, Tao Bai, Jian Wei, Rong Ma, Chuan-Hui Ma, Qiang Huang
Journal of Marine Science and Technology
The flow capacity of the Ningxia-Inner Mongolia reach of the Yellow River has declined substantially for the effects of reservoir regulation, higher concentration of channel sedimentation, reduced upstream inflow, and increased demand for water resources downstream. This has resulted in frequent flooding and ice-related incidents, which severely threaten downstream safety. Accordingly, this paper proposes flow-capacity limitations on the basis of a standardized dike design to acquire optimal safety overflow for the upstream of Yellow River. First, historical data (1946-2012) from six hydrological stations (S1-S6) are collected, and flow capacities covering 1965-2006 (Data 1) and 2007-2010 (Data 2) are compared. Second, …
The Trefftz Test Functions Method For Solving The Generalized Inverse Boundary Value Problems Of Laplace Equation, Chein-Shan Liu, Yung-Wei Chen, Jiang-Ren Chang
The Trefftz Test Functions Method For Solving The Generalized Inverse Boundary Value Problems Of Laplace Equation, Chein-Shan Liu, Yung-Wei Chen, Jiang-Ren Chang
Journal of Marine Science and Technology
The issue of data completion is important for the elliptic type partial differential equation. In the inverse Cauchy problem, we need to complete the boundary data by over-specifying Dirichlet and Neumann data on a portion of the boundary. In this paper, we numerically solve the generalized inverse boundary value problems of Laplace equation in a rectangle with one boundary function and two boundary functions missing, which are more difficult than the inverse Cauchy problem. By using the technique of a boundary integral equation method together with a specially designed Trefftz test function, we can complete the boundary data by requiring …
Analysis Of Power System Low Frequency Oscillation With Empirical Mode Decomposition, Chia-Liang Lu, Chia-Yu Hsu, Pei-Hwa Huang
Analysis Of Power System Low Frequency Oscillation With Empirical Mode Decomposition, Chia-Liang Lu, Chia-Yu Hsu, Pei-Hwa Huang
Journal of Marine Science and Technology
The low frequency oscillation (LFO) in power systems often consists of composite responses of various oscillation modes. Thus a direct analysis of LFO for revealing system dynamic characteristics is not straightforward. The primary objective of this study is to utilize the method of empirical mode decomposition (EMD) to expand the LFO response under study into multiple intrinsic mode functions (IMFs) for detailed investigation of power system dynamics. Then time-frequency power information is explored using wavelet transform to obtain time-frequency power graph which is further resolved into a time-frequencypower diagram. Finally, information from the time-frequencypower diagram is further examined to determine …
A Framework For Integrated Ship Structure Lifecycle Management, Kai Li, Zheng-Yao Yi, Yan-Yun Yu, Ming Chen
A Framework For Integrated Ship Structure Lifecycle Management, Kai Li, Zheng-Yao Yi, Yan-Yun Yu, Ming Chen
Journal of Marine Science and Technology
As the concept of ship structure lifecycle management has emerged, lots of endeavors have been made to apply computeraided (CAX) technologies to various business activities in the whole lifecycle of ship structure. However, information integration or data exchange were barely considered in most of CAX systems development. Hence the systems produce masses of data in their own formats, generate many information islands, and reduce the overall efficiency. It often needs much work of data preparation when downstream systems start working. Information integration can reduce data redundancy, form unified data platform and provide data resource for marine structure lifecycle management. This …
Underwater Image De-Scattering And Enhancing Using Dehazenet And Hwd, Pan-Wang Pan, Fei Yuan, En Cheng
Underwater Image De-Scattering And Enhancing Using Dehazenet And Hwd, Pan-Wang Pan, Fei Yuan, En Cheng
Journal of Marine Science and Technology
De-scattering and edge enhancing are critical procedures for underwater images which suffer from serious contrast attenuation, color deviation, and edge blurring. In this paper, a novel method is proposed to enhance underwater images. Firstly, a Convolutional Neural Network (CNN) is trained end-to-end to estimate the transmission map. Simultaneously, the adaptive bilateral filter is used to refine the transmission map. Secondly, a strategy based on the white balance is proposed to remove the color deviation. Laplace pyramid fusion is utilized to obtain the fusion result of the haze-free and color-corrected image. Finally, the output image is transformed into the Hybrid Wavelets …
Weight Minimization Of Ship Chamber Structure In Vertical Ship Lift Design Based On Multi-Level Structural Optimization Method, Kai Li, Zhengyao Yi, Chuanhui Ling, Zhijiang Yuan, Xiaogang Jiang
Weight Minimization Of Ship Chamber Structure In Vertical Ship Lift Design Based On Multi-Level Structural Optimization Method, Kai Li, Zhengyao Yi, Chuanhui Ling, Zhijiang Yuan, Xiaogang Jiang
Journal of Marine Science and Technology
Weight reduction of ship chamber is a main concern of ship lift design for improving the load capacity. The structure of ship chamber is typical of beam-plate structure. To deal with structural optimization problem of beam-plate structure, a multilevel structural optimization method was developed based on combining an improved bi-directional evolutionary structural optimization (BESO) method and surrogate model method, which covers three optimization levels, as dimension optimization, topology optimization and section optimization. The aim of the proposed optimization method is to determine global design parameters, integral structural topology, and locations and sectional parameters of structural members from an oversized ground …
Bending Mechanical Behavior Analysis Of Glass-Fiber Reinforced Thermoplastic Pipe Based On A Nonlinear Solid Element Model, Shuqing Wang, Lu Yao, Xiangjian Meng
Bending Mechanical Behavior Analysis Of Glass-Fiber Reinforced Thermoplastic Pipe Based On A Nonlinear Solid Element Model, Shuqing Wang, Lu Yao, Xiangjian Meng
Journal of Marine Science and Technology
In this paper, a comprehensive investigation on the bending mechanical behavior of glass-fiber reinforced thermoplastic pipe (RTP) is implemented by using a three-dimensional (3D) solid finite-element (FE) model. A major contribution of this paper is to present a UMAT based equivalence procedure for solid elements, which is capable of considering the material anisotropic nonlinearity of thermoplastic composite pipe (TCP) laminate. First, the linearity and nonlinearity of RTP’s material are incorporated into the numerical analysis and their effects on the bending performance are compared. Then, based on the material nonlinearities, the influences of initial ovality, volume ratio of glass fiber, diameter-to-thickness …
Rotational Inertia Force Effects In Circular Squeeze Films With A Non-Newtonian Ferrofluid, Jaw-Ren Lin, Li-Ming Chu, Long-Jin Liang, Shu-Ting Hu
Rotational Inertia Force Effects In Circular Squeeze Films With A Non-Newtonian Ferrofluid, Jaw-Ren Lin, Li-Ming Chu, Long-Jin Liang, Shu-Ting Hu
Journal of Marine Science and Technology
This paper aims to investigate the effects of rotational inertia force on the squeeze film characteristics between two circular disks lubricated with a non-Newtonian ferrofluid. Based on the Shliomis ferromagnetic fluid model incorporating with the Stokes couple stress fluid model, we have derived a non-Newtonian ferromagnetic Reynolds equation including the rotational inertia force effects for the study of squeeze film performances. From the results, the effects of rotational inertia forces of the upper disk yield a lower load capacity and a shorter squeezing time as compared to the non-rotating case. In addition, the influences of the related parameters on the …
Digital Acoustic Modem Design For Narrowband Underwater Vehicle Communications, Ertan Uysal, Serhat Yılma, Murat Kuzlu
Digital Acoustic Modem Design For Narrowband Underwater Vehicle Communications, Ertan Uysal, Serhat Yılma, Murat Kuzlu
Journal of Marine Science and Technology
Underwater communication has become a crucial data transmission technology for commercial and military marine applications in the last few decades. However, most underwater communication applications still use analogue technologies. Recent advances in digital signal processing technology have enabled numerous applications in different fields, especially in underwater wireless communications. This paper presents a digital underwater communication system, which transmits and receives acoustic signals via hydrophones employed as acoustic transmitters and receiver units. In this study, coding and modulation methods were also implemented in the prototype through a series of simulations.
Sensitivity Analysis Of Steep Wave Riser With Internal Flow, Zhen Liu, Haiyan Guo
Sensitivity Analysis Of Steep Wave Riser With Internal Flow, Zhen Liu, Haiyan Guo
Journal of Marine Science and Technology
Offshore fields, specifically, deepwater oil and gas reserves, have been receiving increasing attention with the increasing consumption of petroleum products. Marine risers are critical to the petroleum industry. The steep wave riser (SWR) is becoming increasingly popular as its use has provided a solution for oil and gas exploration in water depths where traditional rigid risers could not tolerate the environmental loads or would have become very costly. A numerical model of an SWR with internal flow is built based on the slender rod model and the finite element method. The Newton-Raphson and the Newmark- methods are used to solve …
Morphological Characteristics Of Tidal Inlets Subject To A Short Term Typhoon Event: A Case Study In Lanyan River Estuary, Hsing-Yu Wang, Hui-Ming Fang, Sung-Shan Hsiao
Morphological Characteristics Of Tidal Inlets Subject To A Short Term Typhoon Event: A Case Study In Lanyan River Estuary, Hsing-Yu Wang, Hui-Ming Fang, Sung-Shan Hsiao
Journal of Marine Science and Technology
This study aims to investigate different sediment particle sizes subject to transport characteristics of bed-load and suspendedload caused by nonlinear interactions of wave-tide-river in a tidal-estuary. A two-dimensional hydrodynamic coupling to a morphological model is developed to study this issue. A case study of Lanyang River estuary in Taiwan is applied and analyzed. The models are verified against field data (i.e., hydrodynamics and morphological change) collected from Lanyang River estuary during the invasion of typhoon Saola in July, 2012. Fairly good agreements are given comparing to field data. In general, the simulation indicates that suspended load could be transported toward …
Nonlinear Dynamics And Controlling Chaos In A Magnetic Levitation System, Shun-Chang Chang, Jui-Feng Hu, Yeou-Feng Lue
Nonlinear Dynamics And Controlling Chaos In A Magnetic Levitation System, Shun-Chang Chang, Jui-Feng Hu, Yeou-Feng Lue
Journal of Marine Science and Technology
This investigation verifies the chaos motion of a magnetic levitation system with a ferromagnetic ball suspended in a voltage-controlled magnetic field, and explains a system for chaotic control. Then, the detailed dynamic behaviors are numerically investigated by means of Poincaré maps, phase portraits, time responses, and frequency spectra. The results reveal that due to the realistic nonlinear characteristics of magnetic forces, perioddoubling bifurcation has been observed to lead to chaos. Chaotic behavior is verified using Lyapunov exponents and Lyapunov dimensions. Finally, we propose a state feedback control technique for the effective control of a chaotic magnetic levitation system. Some simulation …
Fast Eigenvalue Analysis Of Critical Oscillation Mode For Shipboard Electric Power System, Chao-Chun Li, Pei-Hwa Huang
Fast Eigenvalue Analysis Of Critical Oscillation Mode For Shipboard Electric Power System, Chao-Chun Li, Pei-Hwa Huang
Journal of Marine Science and Technology
Frequency domain analysis has been widely adopted for the study of the small signal stability of the power system. The frequency domain approach includes the linearization of the system to obtain a linear model as well as the system matrix of which the eigenvalues can be calculated to determine the system stability. However, we often have high order of system matrix and thus it will be undesirable to calculate and analyze all the system eigenvalues. This paper is to explore the problem of small signal stability for the shipboard electric power system and the main purpose is to find out …
The Three-Dimensional Flow Simulation Of A Flapping Wing, Lung-Jieh Yang, Ai-Lien Feng, Hsi-Chun Lee, Balasubramanian Esakki, Wei He
The Three-Dimensional Flow Simulation Of A Flapping Wing, Lung-Jieh Yang, Ai-Lien Feng, Hsi-Chun Lee, Balasubramanian Esakki, Wei He
Journal of Marine Science and Technology
This study investigates three-dimensional (3D) flow fields around a flapping wing with a span of 20 cm. Numerical simulations are performed by varying the simulation mesh density for a half-flapping-wing profile with wind tunnel domain for flapping stroke angles of 53 and 90. Wind velocities ranging from 1 to 3 m/s, variation in flapping frequency of 14-15 Hz, and corresponding lift characteristics are obtained. Comparative evaluation of numerical and experimental lift force data reveals the translational and rotational lift phenomena of Dickinson’s mechanisms. The stream line that flows over the 3D wing profile is found to be in good agreement …