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Journal of Marine Science and Technology–Taiwan

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Full-Text Articles in Engineering

Impact Characteristics Of Free Over-Fall In Pool Zone With Upstream Bed Slope, Shi-I Liu, Jen-Yan Chen, Yao-Ming Hong, Hung-Shin Huang, Rajkumar V Raikar Aug 2014

Impact Characteristics Of Free Over-Fall In Pool Zone With Upstream Bed Slope, Shi-I Liu, Jen-Yan Chen, Yao-Ming Hong, Hung-Shin Huang, Rajkumar V Raikar

Journal of Marine Science and Technology–Taiwan

This paper presents the theoretical equations for the impact characteristics of free over-fall (ICFOF) in the pool zone with sloping upstream bed. The various impact characteristics considered are the brink depth, the impact position and impact angle, the tail water depth and the depth of water pool. In order to overcome the complexity in determining the ICFOF, they were expressed in dimensionless forms as functions of upstream bed slope (UBS), upstream Froude number and Drop number. The multiple regression analysis was used to obtain the empirical expressions for the ICFOF using the laboratory experimental results. It was found that the …

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Effects Of Power System Stabilizer On Inter-Area Oscillations In Vietnam Power System, Van-Dien Doan, Ta-Hsiu Tseng, Pei-Hwa Huang Aug 2014

Effects Of Power System Stabilizer On Inter-Area Oscillations In Vietnam Power System, Van-Dien Doan, Ta-Hsiu Tseng, Pei-Hwa Huang

Journal of Marine Science and Technology–Taiwan

The main objective of this paper is to report a preliminary study of the effects of the power system stabilizer on the small-signal stability and the damping of low-frequency oscillations of the Vietnam power system which is under fast development and has a longitudinal grid pattern. Spontaneous low-frequency oscillations are potential to occur in the exchange of regional power flow of a power system with longitudinal network structure under normal operation. The method of eigen-analysis is utilized to perform the study of the inter-area oscillations with an emphasis on the oscillation mode with low frequency and light damping. The eigenvalues, …

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Contrast Enhancement And Visual Effects Based On Gray-Level Grouping, Yen-Ching Chang, Chun-Ming Chang, Li-Chun Lai, Liang-Hwa Chen Aug 2014

Contrast Enhancement And Visual Effects Based On Gray-Level Grouping, Yen-Ching Chang, Chun-Ming Chang, Li-Chun Lai, Liang-Hwa Chen

Journal of Marine Science and Technology–Taiwan

Contrast enhancement plays a crucial role in the field of image processing. Histogram equalization is a simple and automatic method for contrast enhancement. Conventional contrast-enhancement techniques, such as histogram specification and contrast stretching, require manual parameters to achieve satisfactory results. To automatically produce enhanced results for low-contrast images, a new histogram-based optimized contrast-enhancement technique, called gray-level grouping (GLG), was proposed. GLG performs satisfactorily in dark and low-contrast images and always increases the contrast values to a maximum. Extravagant contrast enhancement typically means sacrificing the visual effects of an image. Through scrutinizing the GLG procedure, we discovered potential limitations and observed …

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An Image Display Device Without A Concrete And Definitive Screen, Junewen Chen, Jing-Bin Duan, Li-An Chiu, Chuan-Sheng Hong, Ya-Ping Kang Aug 2014

An Image Display Device Without A Concrete And Definitive Screen, Junewen Chen, Jing-Bin Duan, Li-An Chiu, Chuan-Sheng Hong, Ya-Ping Kang

Journal of Marine Science and Technology–Taiwan

We present a novel and practical hardwareless display system that was developed for the 3-D projection of real objects in the absence of a concrete screen. In this report, the design and experimental results are presented to demonstrate the display of 360°-viewable objects. Images that are projected on an annular stream of aerosol or fluid can penetrate the layerlike aerosols, thereby displaying a 3-D image. Software can be used to normalize the image data to display life-like images of any model, including customers, and various outfits can be added. Moreover, the images can be visualized in full 360°, and the …

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Active Appearance Model Algorithm With K-Nearest Neighbor Classifier For Face Pose Estimation, Bing-Fei Wu, Chih-Chung Kao, Cheng-Lung Jen, Chia-Rong Chiang, Po-Hung Lai Jun 2014

Active Appearance Model Algorithm With K-Nearest Neighbor Classifier For Face Pose Estimation, Bing-Fei Wu, Chih-Chung Kao, Cheng-Lung Jen, Chia-Rong Chiang, Po-Hung Lai

Journal of Marine Science and Technology–Taiwan

In this paper, a face pose estimation (FPE) algorithm using active appearance model (AAM) with a k-nearest neighbor (kNN) classifier is presented. AAM is a model-based image representation method used to describe non-rigid visual objects, with both shape and texture variations, using a mean vector and linear combinations of a set of variation modes. Since AAM is a deformable model, it has several variations. Owing to the variations, the model is adjusted to the input test face image using iterative searching and fitting. The error, which measures the difference between the model and a test image, is minimized with the …

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Design Of A Chart-Based Radar Simulator Augmented With A Multi-Agent Ship Traffic Simulation Platform, Shwu-Jing Chang, Yu-Ting Lai, Chun-Mai Hsu Jun 2014

Design Of A Chart-Based Radar Simulator Augmented With A Multi-Agent Ship Traffic Simulation Platform, Shwu-Jing Chang, Yu-Ting Lai, Chun-Mai Hsu

Journal of Marine Science and Technology–Taiwan

This paper presents a radar simulation system developed under a request to deliver a radar and an Electronic Chart Display and Information System (ECDIS) for the navigation bridge of a ship maneuvering simulator. It is designed to dynamically generate radar image based on the electronic navigational chart database and sensor information to provide flexibility in navigation area for exercise and maintain consistency with other sensors or systems of the bridge, especially the ECDIS. Since the successful delivery of our study, the radar simulation system has been augmented with a Multi-Agent Ship Traffic (MAST) simulation platform and evolved into a versatile …

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Linear State Feedback Design For Surge Control Of Axial Flow Compressor Dynamics, Der-Cherng Liaw, Yun-Hua Huang, Wen-Ching Chung Jun 2014

Linear State Feedback Design For Surge Control Of Axial Flow Compressor Dynamics, Der-Cherng Liaw, Yun-Hua Huang, Wen-Ching Chung

Journal of Marine Science and Technology–Taiwan

Based on Moore and Greitzer’s model [15], the surge behavior of axial flow compression system was found to be attributed to the appearance of Andronov-Hopf bifurcationin [12]. In this paper, we focus on the design of control law to prevent and/or delay the occurrence of the bifurcations, which will then suppress the surge behavior. Both types of linear dynamic state feedback and linear washout filter controllers are proposed. The proposed washout design does not require the explicit knowledge of the operating point and keep the original equilibrium characteristic while the dynamic feedback design will change the equilibrium operating points for …

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Dynamic Output Feedback Sliding Mode Controller Design For Chattering Avoidance, Jeang-Lin Chang, Jui-Che Tsai Jun 2014

Dynamic Output Feedback Sliding Mode Controller Design For Chattering Avoidance, Jeang-Lin Chang, Jui-Che Tsai

Journal of Marine Science and Technology–Taiwan

For a class of linear MIMO uncertain systems, a dynamic output feedback sliding mode control algorithm that avoids the chattering problem and high gain control is proposed in this paper. Without using any differentiator, we develop a modified asymptotically stable second order sliding mode control law in which the developed controller can guarantee the finite time convergence to the sliding mode and the system states asymptotically approach to zero. Finally, a numerical example is explained for demonstrating the applicability of the proposed scheme.

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Development Of A Strapdown Inertial Navigation System Simulation Platform, Dah-Jing Jwo, Jyun-Han Shih, Chia-Sheng Hsu, Kai-Lun Yu Jun 2014

Development Of A Strapdown Inertial Navigation System Simulation Platform, Dah-Jing Jwo, Jyun-Han Shih, Chia-Sheng Hsu, Kai-Lun Yu

Journal of Marine Science and Technology–Taiwan

This paper presents a strapdown inertial navigation system (SINS) simulation platform. The numerical simulator solves the navigation equations in navigation frame where the quaternion vector is employed for attitude calculation. The measured quantities (angular body rates and specific force) are generated by the numerical simulator. The results are also confirmed with the navigation solutions given by a commercial inertial navigation system toolbox using the generated body angular rates and specific force of the SINS. The paper can provide the readers with further information for developing their own SINS simulation tools.

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Wavelet Support Vector Machine For Face Recognition, Chen-Chia Chuang, Ping-Lun Liao, Jin-Tsong Jeng Jun 2014

Wavelet Support Vector Machine For Face Recognition, Chen-Chia Chuang, Ping-Lun Liao, Jin-Tsong Jeng

Journal of Marine Science and Technology–Taiwan

In this paper a tool system with wavelet support vector machine (WSVM) under dimension reduction for face recognition is proposed. Eigenfaces and fisherfaces are the major methods used to reduce the dimension of face images in the proposed face recognition tool system. At the same time, noise interference image cases, namely Gaussian noise, with no ears and no eyes are also considered in this paper. Finally, the implementation of proposed system is based on objectoriented design software; the dimension reduction and wavelet kernel support vector machine are applied to the proposed tool system that can deal with face recognition problems …

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Mimo Transmission In Spatially Correlated Fading, Joy Iong-Zon Chen, Chi-Tsung Huang, Yu-Hsing Chien Jun 2014

Mimo Transmission In Spatially Correlated Fading, Joy Iong-Zon Chen, Chi-Tsung Huang, Yu-Hsing Chien

Journal of Marine Science and Technology–Taiwan

A multiple-input, multiple-output (MIMO) system transmission over a channel characterized by spatially correlated fading is addressed in this article. Two scenarios that involved using well-known statistical fading distributions, correlatedRician and correlated-Nakagami-m fading, were deployed in analysis. The moment-generating function obtained using a stochastic process was applied to determine the ergodic, or average, channel capacity, thus by passing the difficulty traditionally associated with calculating the probability density function of the signal-to-noise ratio. The results of several numerical and Monte-Carlo comparisons are offered for validating the accuracy of the theoretically derived formulae. Furthermore, many plots were designed by combining different numbers of …

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Global Localization Using Dead-Reckoning And Kinect Sensors For Robots With Omnidirectional Mecanum Wheels, Ching-Chih Tsai, Feng-Chun Tai, Yu-Cheng Wang Jun 2014

Global Localization Using Dead-Reckoning And Kinect Sensors For Robots With Omnidirectional Mecanum Wheels, Ching-Chih Tsai, Feng-Chun Tai, Yu-Cheng Wang

Journal of Marine Science and Technology–Taiwan

This paper presents a low-cost global pose localization method using least-squares method and extended Kalman filter (EKF) for an anthropomorphous dual-arm mobile robot (ADAMR) driven by omnidirectional Mecanum wheels in indoor environments. This method is developed by fusing measurements from the KINECT sensor and four encoders mounted on the omnidirectional Mecanum wheels. The KINECT sensor is used to recognize landmarks in the working environments of the robot, and then obtain the azimuth angles and distances between these landmarks and the robot. Based on these measured information, a static global pose initialization algorithm using least-squares method is applied to estimate both …

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A Particle Swarm Optimization-Like Algorithm For Constrained Minimal Spanning Tree Problems, Chun-Chao Yeh, Ying-Che Chien Jun 2014

A Particle Swarm Optimization-Like Algorithm For Constrained Minimal Spanning Tree Problems, Chun-Chao Yeh, Ying-Che Chien

Journal of Marine Science and Technology–Taiwan

Previous studies have discussed various constrained minimal spanning tree (MST) problems. In this paper, we propose an efficient algorithm for solving a class of constrained MST problems. The proposed PSO (Particle Swarm Optimization)- like strategy for solving constrained MST problems identifies optimal MSTs under degree and delay constraints. The solution quality and computation time of the proposed PLCMST (PSO-Like algorithm for Constrained MST problems) algorithm is compared with two other algorithms: one based on ant colony optimization, and the other based on a genetic algorithm strategy. Our experimental results show that the PLCMST outperforms the other two approaches, particularly when …

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A Wheeled Mobile Robot Path-Tracking System Based On Image Processing And Adaptive Cmac, Jih-Gau Juang, Ko-Jui Hsu, Chih-Min Lin Jun 2014

A Wheeled Mobile Robot Path-Tracking System Based On Image Processing And Adaptive Cmac, Jih-Gau Juang, Ko-Jui Hsu, Chih-Min Lin

Journal of Marine Science and Technology–Taiwan

This study entailed applying image-processing techniques and an intelligent control method to a wheeled mobile robot (WMR) for real-time trajectory recognition and tracking. The WMR was fitted with a charge-coupled device (CCD) camera to capture images of the environment, and the hue-saturationintensity color space was used to classify the color features of the captured images. The WMR calculates the relative position of a target object by using image-processing and edgedetection algorithms. This paper proposes a cerebellar model articulation controller (CMAC) and adaptive CMAC to replace conventional proportional-integral-derivative (PID) controller for guiding the WMR to track a desired path. Moreover, using …

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The Development Of A Cost-Effective And Optimized Dp-Spiv System For Fluid Turbulence Researches, Yu-Chi Chang, Yi-Hung Chang, Yaw-Huei Lee, Yi-Chih Chow Jun 2014

The Development Of A Cost-Effective And Optimized Dp-Spiv System For Fluid Turbulence Researches, Yu-Chi Chang, Yi-Hung Chang, Yaw-Huei Lee, Yi-Chih Chow

Journal of Marine Science and Technology–Taiwan

Turbulent flows and issues of turbulence modeling have long been intriguing and important in fluid researches and practices. The mean or instantaneous velocity gradient tensors with six independent components, or other tensorial variables involving gradients, play a key role in turbulence dynamics and models. The advancement of the knowledge of these parameters relies on measurement systems built on sophisticated flow diagnostic techniques that enable both detailed and complete measurements. However, such systems seem inevitably complicated to operate and costly to build and maintain. Therefore, we develop and optimize a dual-plane stereoscopic particle image velocimetry (DP-SPIV) system that is much more …

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Numerical Modeling Of Wave-Induced Rotations Of A Bottom-Hinged Flapper With A Sph Model, Da-Wei Chen, Shiaw-Yih Tzang, Chih-Min Hsieh, Yi-Chih Chow, Jiahn-Horng Chen, Chen-Chou Lin, Robert Rong-Jiann Hwang Jun 2014

Numerical Modeling Of Wave-Induced Rotations Of A Bottom-Hinged Flapper With A Sph Model, Da-Wei Chen, Shiaw-Yih Tzang, Chih-Min Hsieh, Yi-Chih Chow, Jiahn-Horng Chen, Chen-Chou Lin, Robert Rong-Jiann Hwang

Journal of Marine Science and Technology–Taiwan

In this study, a Smoothed Particle Hydrodynamics model for simulating wave-induced rotations of a bottom-hinged flapper was established in a 2-D numerical wave flume. The simulated rotating angles illustrated that the flapper could swing back and forth following harmonic wave loadings. The simulations were also seen to be in good agreement with experimental data, confirming the applicability of the present numerical model. The simulated hydrodynamic behaviors at different phases showed that the flapper moved downstream under the wave crest and upstream under the wave trough following the elliptical form of water particle trajectory. The energy conversions of a flapper during …

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Application Of Adaptive Variable Speed Back-Stepping Sliding Mode Controller For Pmlsm Position Control, Mei-Yung Chen, Jian-Shiun Lu Jun 2014

Application Of Adaptive Variable Speed Back-Stepping Sliding Mode Controller For Pmlsm Position Control, Mei-Yung Chen, Jian-Shiun Lu

Journal of Marine Science and Technology–Taiwan

In this research, an adaptive variable speed back-stepping sliding mode controller (AVSBSMC) is proposed to control the permanent magnet linear synchronous motor (PMLSM) on high-precision positioning servo system platform. This controller combines the dynamic features of variable speed control (VSC) and the positioning characteristics of adaptive back-stepping sliding mode control (ABSMC). Firstly, the detailed dynamic machine model of PMLSM is established. Secondly, the proportional-integral-derivative (PID) and ABSMC controllers are proposed to compensate the uncertainties in position control. Then, the one provides the better servo performances is the position controller in the motor system. Thirdly, the variable speed controller (VSC) and …

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Reproducing Laboratory-Scale Rip Currents On A Barred Beach By A Boussinesq Wave Model, Ke-Zhao Fang, Ji-Wei Yin, Zhi-Li Zou, Zhong-Bo Liu, Ping Dong Apr 2014

Reproducing Laboratory-Scale Rip Currents On A Barred Beach By A Boussinesq Wave Model, Ke-Zhao Fang, Ji-Wei Yin, Zhi-Li Zou, Zhong-Bo Liu, Ping Dong

Journal of Marine Science and Technology–Taiwan

The pioneering work of Haller [8] on physically investigating bathymetry-controlled rip currents in the laboratory is a standard benchmark test for verifying numerical nearshore circulation models. In this paper, a numerical model based on higher-order Boussinesq equations was developed to reproduce the number of experiments involved in such an investigation, with emphasis on the effect of computational domain size on the numerical results. A set of Boussinesq equations with optimum linear properties and second-order full nonlinearity were solved using a higher-order finite difference scheme. Wave breaking, moving shoreline, bottom friction, and mixing were all treated empirically. The developed model was …

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A Modelling Study Of Seawater Intrusion In The Liao Dong Bay Coastal Plain, China, Fei Ding, Takao Yamashita, Han Soo Lee, Graduate School For International Development And Cooperation, Hiroshima University, Higashi-Hiroshima, Japan Pan Apr 2014

A Modelling Study Of Seawater Intrusion In The Liao Dong Bay Coastal Plain, China, Fei Ding, Takao Yamashita, Han Soo Lee, Graduate School For International Development And Cooperation, Hiroshima University, Higashi-Hiroshima, Japan Pan

Journal of Marine Science and Technology–Taiwan

To investigate the extent of seawater intrusion in the Liao Dong Bay coastal plain, China, a numerical model for variable-density groundwater flow and miscible salt transport was developed. The SEAWAT code was used to solve the density-dependent groundwater flow and solute transport governing equations. The simulation was conducted for 55 months from October, 2004 to April, 2009. The numerical model was calibrated by the hydraulic heads measured in April, 2009. Using the calibrated model and the same hydrogeological conditions in 2004, the extent of seawater intrusion prediction was conducted for the next 40 years. The results show that the extent …

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Risk Assessment In Ship Hull Structure Production Using Fmea, Murat Ozkok Apr 2014

Risk Assessment In Ship Hull Structure Production Using Fmea, Murat Ozkok

Journal of Marine Science and Technology–Taiwan

In the competitive environment, shipyards attempt to reduce failures in their production system in order to maintain their competitive power. Failures cause some damages such as injuries and deaths to the shipyard. Most of the damage causes work loss in the shipyard. To mitigate this damage, the most risky activities and work stations must be identified. For this, the risk levels of the failures must be calculated by applying the Failure Mode and Effects Analysis Method. In this study, the hull structure production process of a shipyard was considered. After collecting the failure statistical data of a shipyard, the failures …

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Experimental Study Of Characteristics Of Motions Of A Large Mooring Ship In Long-Period Waves, Xian-Ying Shi, Ning-Chuan Zhang, Chang-Ping Chen, Heng-Zhi Jiang, Lei Cui Apr 2014

Experimental Study Of Characteristics Of Motions Of A Large Mooring Ship In Long-Period Waves, Xian-Ying Shi, Ning-Chuan Zhang, Chang-Ping Chen, Heng-Zhi Jiang, Lei Cui

Journal of Marine Science and Technology–Taiwan

By using the method of physical model tests, the characteristics of mooring ship’s motion responses in transverse long-period waves have been studied under different conditions, including such elements as loading conditions, wave heights, and specific patterns of mooring, etc. The results indicate that: the mooring ship’s movements of surge, sway and yaw had their own natural periods; the movement of sway was a period motion. The ratio of the natural period of sway and the natural rolling period of the mooring ship was within 1.11~1.23. The peak value of sway grew along with the increase of the wave period; the …

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Surface Modification Of Ato Photocatalyst On Its Bactericidal Effect Against Escherichia Coli, Hshiang-Ho Chiang, Shing-Hoa Wang, Hsin-Yiu Chou, Chih-Ching Huang, Tsung-Lun Tsai, Yi-Che Yang, Jyh-Wei Lee, Tai-Yuan Lin, Yeun-Jung Wu, Chien-Chon Chen Apr 2014

Surface Modification Of Ato Photocatalyst On Its Bactericidal Effect Against Escherichia Coli, Hshiang-Ho Chiang, Shing-Hoa Wang, Hsin-Yiu Chou, Chih-Ching Huang, Tsung-Lun Tsai, Yi-Che Yang, Jyh-Wei Lee, Tai-Yuan Lin, Yeun-Jung Wu, Chien-Chon Chen

Journal of Marine Science and Technology–Taiwan

The increases in catalytic photolysis efficiency of the surface modified ATO (anodic titanium oxide) by Ag or/and Au nanoparticles were attributed to the greater light absorbance than that of the sole ATO. In addition to the enhanced inherent ATO absorbance at 365 nm inasmuch as the surface-plasmon enhancement of the band emission, additional light absorbance peak occurred at the wavelength around 430 nm, 530 nm and 500 nm for nano Ag modified TiO2, nano Au modified TiO2, and composite nano Ag/Au modified TiO2, respectively. All surface modified ATO catalysts exhibited stronger bactericidal effect under UV exposure than under visible light …

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The Numerical Study Of The Dynamic Behavior Of An Underwater Vehicle, Tsung-Lung Liu, Kuan-Cheng Pan Apr 2014

The Numerical Study Of The Dynamic Behavior Of An Underwater Vehicle, Tsung-Lung Liu, Kuan-Cheng Pan

Journal of Marine Science and Technology–Taiwan

How to employ numerical methods to predict the dynamic behavior of underwater vehicles will become important in the near future. Over the past decade, the results obtained from the Computational Fluid Dynamics (CFD) methods had been proven similar to that of experimental approach with the same test conditions. In order to reduce the computational time of such flow simulation, the concept of relative motion with body-fixed and fluid-moving scheme is usually employed as a conventional procedure to figure out the flow physics around moving bodies. However, the dynamic influence of fluid on a moving vehicle is self-evident and the relative …

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Truncated Model Tests For Mooring Lines Of A Semi-Submersible Platform And Its Equivalent Compensated Method, Dong-Sheng Qiao, Jin-Ping Ou Apr 2014

Truncated Model Tests For Mooring Lines Of A Semi-Submersible Platform And Its Equivalent Compensated Method, Dong-Sheng Qiao, Jin-Ping Ou

Journal of Marine Science and Technology–Taiwan

This study conducted a model test of 1:100 model scale of a semi-submersible platform with a 1500 m full-depth mooring system in the Joint Laboratory of Wind Tunnel & Wave Flume at Harbin Institute of Technology. A truncated mooring system of 400 m water depth was designed based on the static equivalent principle. The semi-submersible platform was tested under regular wave excitation periods that ranged from 10 s to 45 s and one year of irregular wave conditions in the South China Sea. The results validated the feasibility of using numerical simulation in the motions calculation of semisubmersible platform and …

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Liquefaction Potential Of Non-Plastic Silty Sand, Chun-Chi Chen, Wei F Lee, Jing-Wen Chen, Kenji Ishihara Apr 2014

Liquefaction Potential Of Non-Plastic Silty Sand, Chun-Chi Chen, Wei F Lee, Jing-Wen Chen, Kenji Ishihara

Journal of Marine Science and Technology–Taiwan

This paper is to introduce research progress on liquefaction potential of undisturbed high fines content non-plastic silty sand. A new sampling technique that was applied to the field allowing sensitive and high fines content silty sand material to be retrieved in sounding condition is described. Laboratory tests on the liquefaction resistance of non-plastic silty sand that emphasized on the influence of fines content percentages were conducted. It concludes that soil liquefaction would occur in non-plastic silty sand deposits even with high nonplastic fines contents. Both fines contents and void ratios have deterministic influences to the cyclic resistance of such silty …

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Exponential Stability Analysis For Neural Networks With Time-Varying Delay And Linear Fractional Perturbations, Chang-Hua Lien, Ker-Wei Yu Apr 2014

Exponential Stability Analysis For Neural Networks With Time-Varying Delay And Linear Fractional Perturbations, Chang-Hua Lien, Ker-Wei Yu

Journal of Marine Science and Technology–Taiwan

In this paper, the global exponential stability and global asymptotic stability for a class of uncertain delayed neural networks (UDNNs) with time-varying delay and linear fractional perturbations are considered. Delay-dependent and delay-independent criteria are proposed to guarantee the robust stability of UDNNs via linear matrix inequality (LMI) approach. Additional nonnegative inequality approach is used to improve the conservativeness of the stability criteria. Some numerical examples are illustrated to show the effectiveness of our results. From the simulation results, significant improvement over the recent results can be observed.

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Combined Effects Of Magnetic Field And Surface Roughness On Long Journal Bearing Lubricated With Ferrofluid, Tze-Chi Hsu, Jing-Hong Chen, Hsin-Lu Chiang, Tsu-Liang Chou Apr 2014

Combined Effects Of Magnetic Field And Surface Roughness On Long Journal Bearing Lubricated With Ferrofluid, Tze-Chi Hsu, Jing-Hong Chen, Hsin-Lu Chiang, Tsu-Liang Chou

Journal of Marine Science and Technology–Taiwan

This study investigated the influence of ferrofluids on the lubrication performance of long journal bearings under the combined effects of stochastic surface roughness and a magnetic field generated by an infinitely long wire. According to our results, placing an infinitely long wire magnetic field at an appropriate distance from the center of the bearing can suppress side leakage in long journal bearings, thereby extending the life of the bearings. Under a higher power-law index and induced magnetic force, the introduction of transverse roughness can enhance film pressure and load capacity, while reducing the attitude angle and modified friction coefficient. The …

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Hydrodynamic Study Of A Fixed Pontoon Structure Under Wave Loads With Different Reynolds Numbers, Parviz Ghadimi, Farzam Safarzadeh Maleki, Mohammad A. Feizi Chekab Apr 2014

Hydrodynamic Study Of A Fixed Pontoon Structure Under Wave Loads With Different Reynolds Numbers, Parviz Ghadimi, Farzam Safarzadeh Maleki, Mohammad A. Feizi Chekab

Journal of Marine Science and Technology–Taiwan

As a breakwater, a suspended fixed pontoon is expected to receive energy of the wave and to reduce the wave height at downstream as much as possible. However, in other applications like floating bridges, the structure is expected to allow the wave to pass with the lowest possible energy absorption. In the present study, a numerical investigation has been conducted to identify the effective types of floating pontoon with different rectangular and circular cross sections under regular waves at different Reynolds numbers. Volume of fluid scheme and finite volume methods have been applied for tracking the free surface and discretization …

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Evaluating Current Fire Test Methods For Determining Flammability Performance Of Ceiling Materials, Wei-Ting Chung, Ming-Yuan Lei, Kuang-Chung Tsai Apr 2014

Evaluating Current Fire Test Methods For Determining Flammability Performance Of Ceiling Materials, Wei-Ting Chung, Ming-Yuan Lei, Kuang-Chung Tsai

Journal of Marine Science and Technology–Taiwan

Many fire tests have been developed to evaluate the flammability performance of lining materials. According to the test methods, specimens are traditionally mounted vertically as a wall or horizontally as a floor. The only exception is the ISO 9705 room corner test in which ceiling material is installed beneath a ceiling. This study was accordingly designed to discuss the test results of ceiling materials in the ISO 9705 room corner test with the testing capacity of the traditional tests to evaluate the feasibility of the traditional tests to rank materials mounted beneath a ceiling. Materials used were gypsum board and …

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Effects Of Sweep Angles And Angles Of Attack On Junction-Flow Patterns, Kuo-Ching San, Ying-Zong Lin, Shun-Chang Yen Apr 2014

Effects Of Sweep Angles And Angles Of Attack On Junction-Flow Patterns, Kuo-Ching San, Ying-Zong Lin, Shun-Chang Yen

Journal of Marine Science and Technology–Taiwan

This study utilized the NACA 0012 finite wings to investigate the effects of wing sweep angle (Λ) and angle of attack (α) on the junction vortex at Re = 8 × 104 . The junction-vortex structures are visualized using the surface oil-flow visualization. The junction vortex is classified as — separation, attached, bubble, and bluff-body wake modes. The separation mode occurs at Λ < 12° and α < 5°. The attached mode occurs at low α for a swept-back wing (Λ > 0°) and the bluff-body wake mode occurs at high α for a forward-swept wing (Λ < 0°). Furthermore, the bubble mode occurs at high sweep angle (i.e., high backward sweep angle) and high angle of attack. Moreover, the properties of velocity vectors, normal stress and shear stress are also detected and analyzed using an X-type hot-wire anemometer.

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