Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Journal of Marine Science and Technology–Taiwan

Discipline
Keyword
Publication Year

Articles 691 - 720 of 1299

Full-Text Articles in Engineering

A Study On Optimization Of Ship Hull Form Based On Neuro-Response Surface Method (Nrsm), Soon-Sub Lee, Jae-Chul Lee, Sung-Chul Shin, Soo-Young Kim, Hyun-Sik Yoon Dec 2014

A Study On Optimization Of Ship Hull Form Based On Neuro-Response Surface Method (Nrsm), Soon-Sub Lee, Jae-Chul Lee, Sung-Chul Shin, Soo-Young Kim, Hyun-Sik Yoon

Journal of Marine Science and Technology–Taiwan

Building large and eco-friendly ships has become a clear trend in the ship building industry. Research to minimize ship resistance has actively been investigated for energy savings and environmental protection. However, optimization of the full geometry, while taking into account the hydrodynamic performance is difficult because extensive time is needed to calculate the performance factors, such as the resistance and propulsion. Hence we suggest an optimal design framework based on the neuro-response surface method (NRSM) for optimal shape design in consideration of hydrodynamic performance. The optimization algorithm of the constructed framework consists of the back-propagation neural network (BPN) and the …

Go to article

Research On Sealing Performance Of Hydrostatic Pressure Mechanical Seal, Wei-Bing Zhu, He-Shun Wang, Sheng-Ren Zhou Dec 2014

Research On Sealing Performance Of Hydrostatic Pressure Mechanical Seal, Wei-Bing Zhu, He-Shun Wang, Sheng-Ren Zhou

Journal of Marine Science and Technology–Taiwan

The hydrostatic pressure mechanical seal has many advantages, and it can be used in rotating machines with lower speed. Based on the externally pressurized stable gas lubrication theory, the control equation of end face flow field for hydrostatic pressure mechanical seal with orifice compensation was established. The functional extremum algorithm and the finite element method were used to solve this equation. The effects of gas film thickness, air supply pressure, throttle orifice number and diameter, on face opening force and gas film stiffness were discussed in detail. The results show that the opening force decreases with the widening of face …

Go to article

Performance Evaluation Of Three Types Of Passive Micromixer With Convergent-Divergent Sinusoidal Walls, Arshad Afzal, Kwang-Yong Kim Dec 2014

Performance Evaluation Of Three Types Of Passive Micromixer With Convergent-Divergent Sinusoidal Walls, Arshad Afzal, Kwang-Yong Kim

Journal of Marine Science and Technology–Taiwan

A passive split-and-recombination micromixer with convergent-divergent channel walls of sinusoidal variation has been investigated using numerical simulations. With water and ethanol as working fluids, the analysis was performed using Navier-Stokes equations with convection-diffusion model in a Reynolds number range, 10  Re  70. Performances of three configurations with different split-and-recombination arrangements were evaluated in terms of mixing index and pressure drop. A parametric study was also conducted with two geometrical parameters, i.e., the ratios of throat-width to diameter of circular wall and diameter of circular wall to amplitude. The results showed a significant dependence of the mixing performance on …

Go to article

Design Of A New Electromagnetic Valve With A Hybrid Pm/Em Actuator In Si Engines, Ly Vinh Dat, Yaojung Shiao Dec 2014

Design Of A New Electromagnetic Valve With A Hybrid Pm/Em Actuator In Si Engines, Ly Vinh Dat, Yaojung Shiao

Journal of Marine Science and Technology–Taiwan

Numerous devices have been developed for controlling valve timings in SI engines. Among them, the electromagnetic valve train (EMV) actuator can fully control valve timings to improve fuel consumption and emission. In addition, an EMV with a permanent-magnet and electromagnetic-coil (PM/EM) hybrid actuator has several advantages of control, energy consumption, and time response compared over conventional EMVs. This paper proposes a novel EMV with a PM/EM hybrid actuator that differs considerably from existing EMVs. Finite element analysis was used for analyzing the EMV design. The optimization was based on criteria that ensured the EMV to satisfy holding forces in closed …

Go to article

Effective Orifice Area Of A Newly Developed Polyurethane Aortic Valve: Manufacturing And Evaluation, Wu-Chiao Shih, Ha-Hai Vu, Cheung-Hwa Hsu, Kai-Wen Yang, Yaw-Hong Kang Dec 2014

Effective Orifice Area Of A Newly Developed Polyurethane Aortic Valve: Manufacturing And Evaluation, Wu-Chiao Shih, Ha-Hai Vu, Cheung-Hwa Hsu, Kai-Wen Yang, Yaw-Hong Kang

Journal of Marine Science and Technology–Taiwan

An optimal design for a polyurethane (PU) aortic valve was developed in a previous study. The current study investigated an approach for manufacturing PU aortic valves, evaluating the effective orifice areas (EOAs) of the prototypes. Two manufacturing approaches, assembly and single-piece forming methods, were developed. In the assembly method, support frames and valve leaflets were manufactured separately and then glued together by using an adhesive substance. By contrast, in the single-piece forming method, two main components of the valve were fabricated simultaneously by using a molding technique. This study established an experimental loop that mimics natural circulation from the left …

Go to article

Discoid And Asymmetrical Gyroless Micro-Satellite Off-Modulation Attitude Control With Kalman Filter, Ho-Nien Shou Dec 2014

Discoid And Asymmetrical Gyroless Micro-Satellite Off-Modulation Attitude Control With Kalman Filter, Ho-Nien Shou

Journal of Marine Science and Technology–Taiwan

The gyroless attitude control method and kalman algorithm procedures presented in this paper are applicable to asymmetrical microsatellites of any shape with large mass variation and without angular rate sensors. The attitude sensors include a three-axis magnetometer, a horizon sensor, and a coarse sun sensor (CSS), which together serve as an analytic platform and help in ensuring the stability of attitude controls. The attitude control problem of microsatellites has become a focal point because microsatellite fabrication processes are short, costless, and can be flexibly used for various purposes. The center of mass of the microsatellite can be offset because of …

Go to article

Applying Fuzzy Logic Controller To Intelligent Solar Panel Cleaning System, Cong-Hui Huang Dec 2014

Applying Fuzzy Logic Controller To Intelligent Solar Panel Cleaning System, Cong-Hui Huang

Journal of Marine Science and Technology–Taiwan

This paper presents an intelligent solar panel cleaning system that utilizes a fuzzy logic controller. The output voltage of the solar panel is applied to calculate whether to activate the cleaning mechanism. The direction and position of the system is set using a light sensor that is parallel to the direction of the sunlight. The data from the light sensors, combined with fuzzy logic control software developed using LabVIEW, determine the control commands (stop, forward, and reverse) for the stepper motors controlling the cleaning process. The cleaning process, which is repeated until the power output from the solar panels is …

Go to article

Synthetic Physical Models For Animating Unsteady Fish Motions, Shyh-Kuang Ueng, Hong-Kai Chen Dec 2014

Synthetic Physical Models For Animating Unsteady Fish Motions, Shyh-Kuang Ueng, Hong-Kai Chen

Journal of Marine Science and Technology–Taiwan

This paper presents physical models for simulating unsteady fish motions, including bursting, gliding, braking, turning, ascending and descending. A new wave model, the controllable body wave model, is developed to undulate the fish body to produce bursting and gliding motions. A key frame approach is adopted to realize braking, turning, descending and ascending. In the key frame method, individual motions are decomposed into sequences of key steps. The gestures of the fish in these key steps are recorded and regarded as key frames. In the run time, these recorded key frames are sequentially reproduced to generate swimming patterns. In addition …

Go to article

Modeling And Control Of A Novel Ball Screw Mechanism, Wen-Hsiang Hsieh, Kai-Bi Chang Dec 2014

Modeling And Control Of A Novel Ball Screw Mechanism, Wen-Hsiang Hsieh, Kai-Bi Chang

Journal of Marine Science and Technology–Taiwan

This study proposes a systematic approach for the design and control of a novel ball screw transmission system. We investigated the structure of the system, performed kinematic analysis, and conducted dimensional synthesis by optimization. The mathematical model of the system was determined by system identification and a refined PID controller was designed. Computer simulation was conducted to verify the feasibility of the proposed design. A prototype machine and an experimental setup were built and tested. The experimental results show that the output with the controller agrees well with the required output. Therefore, the proposed design can produce the expected output …

Go to article

Fault Diagnosis And Performance Assessment For A Rotary Actuator Based On Neural Network Observer, Jian Ma, Xin Li, Chen Lu, Zi-Li Wang Dec 2014

Fault Diagnosis And Performance Assessment For A Rotary Actuator Based On Neural Network Observer, Jian Ma, Xin Li, Chen Lu, Zi-Li Wang

Journal of Marine Science and Technology–Taiwan

Substantial damage may occur when a rotary actuator fails during operation. Therefore, effective fault diagnosis of a rotary actuator is crucial to ensuring the safety of the device. However, only a few studies on fault detection, fault isolation, and performance assessment have focused on rotary actuators. In this study, fault detection and fault isolation processes were implemented by designing two observers based on a neural network, and a method that assesses the performance of the rotary actuator is proposed. First, two observers are established according to the structure of the rotary actuator. Data in their normal state are used to …

Go to article

Analysis Of Rolled Piece Deformation In Straightening Process Using Fm-Bem, Hai-Lian Gui, Qiang Li, Yao Li, Pu Li, Qing-Xue Huang Oct 2014

Analysis Of Rolled Piece Deformation In Straightening Process Using Fm-Bem, Hai-Lian Gui, Qiang Li, Yao Li, Pu Li, Qing-Xue Huang

Journal of Marine Science and Technology–Taiwan

Rolled piece deformation in a straightening process is regarded as an inverse problem of the plate bending problem. The straightening force was obtained accurately by applying the fast multipole boundary element method (FM-BEM) to the plate bending problem. Furthermore, the straightening process of a nine-roller straightening roller system with a variable roller distance was simulated using numerical analysis, and a function describing the neutral layer offset was obtained from an analysis of FM-BEM results. In this paper, the principle stress values and neutral layer offset of the microunits in the tension and compression regions are discussed. It is concluded that …

Go to article

Nonlinear Wave Evolution Above Rectangular Submerged Structures, Jaw-Fang Lee, Lih-Fu Tu, Cheng-Chi Liu Oct 2014

Nonlinear Wave Evolution Above Rectangular Submerged Structures, Jaw-Fang Lee, Lih-Fu Tu, Cheng-Chi Liu

Journal of Marine Science and Technology–Taiwan

In this study, an analytic approach for the complete second-order solution proposed by Sulisz and Hudspeth [13] was applied to solve a problem of waves propagating over a rectangular submerged structure. In addition, nonlinear wave evolutions above the submerged structure were studied. The nonlinear problem was expressed up to the second-order boundary value problems by using a Taylor series expansion and the perturbation method. In solving the problem, the nonhomogeneous problem was divided into Stokes wave and free wave counterparts. The solutions of neighboring regions were combined and solved by applying kinematic and dynamic matching conditions. Convergence of the presented …

Go to article

Analytical Solution For Long-Wave Scattering By A Submerged Cylinder In An Axi-Symmetrical Pit, Huan-Wen Liu, Xiao-Ling Sun Oct 2014

Analytical Solution For Long-Wave Scattering By A Submerged Cylinder In An Axi-Symmetrical Pit, Huan-Wen Liu, Xiao-Ling Sun

Journal of Marine Science and Technology–Taiwan

This paper proposes an analytical solution to the long-wave equation for waves propagating over a submerged cylinder located in a pit. The pit was assumed to be axi-symmetrical and convex or concave in shape, which may represent a submerged sill being scoured at its toe. Techniques of variable separation and Taylor series expansion were applied to find the analytical solution. It is found that Longuet-Higgins’ classical analytical solutions for waves scattered by a submerged circular sill and by a submerged circular pit are actually special cases of the present analytical solution. By using this analytical solution, the influence of the …

Go to article

Simple Integral Fuzzy Control For Converters With Highly Nonlinear Dynamics, Kuang-Yow Lian, Chi-Wang Hong Oct 2014

Simple Integral Fuzzy Control For Converters With Highly Nonlinear Dynamics, Kuang-Yow Lian, Chi-Wang Hong

Journal of Marine Science and Technology–Taiwan

A simple integral Takagi-Sugeno (T-S) fuzzy control scheme suitable for many types of converters is proposed in this paper. A converter with highly nonlinear characteristics, called active high power factor correction (AHPFC), is taken as an example to show the control scheme. Indeed, we can derive a linear controller to achieve zero output regulation error for the AHPFC converter. First, we include an integral error signal to form an augmented system. After translating the coordinate to the regulated point, we obtain the stabilization model. The model-based fuzzy approach is then used to handle the nonlinear system. The system stability is …

Go to article

Magneto-Hydrodynamic Non-Newtonian Curved Circular Squeeze Films, Jaw-Ren Lin, Li-Ming Chu, Chi-Ren Hung, Rong-Fang Lu Oct 2014

Magneto-Hydrodynamic Non-Newtonian Curved Circular Squeeze Films, Jaw-Ren Lin, Li-Ming Chu, Chi-Ren Hung, Rong-Fang Lu

Journal of Marine Science and Technology–Taiwan

The squeeze film performances between curved circular plates lubricated with an electrically conducting non-Newtonian fluid in the presence of external magnetic fields are investigated in this paper. Based upon the magneto-hydrodynamic flow theory together with the Stokes microcontinuum theory, the magneto-hydrodynamic non-Newtonian Reynolds equation is derived and applied to predict the curved circular squeeze film behaviors. Comparing with the hydrodynamic Newtonian case, the squeeze film characteristics for curved circular plates are improved by the use of an electrically conducting non-Newtonian fluid in the presence of external magnetic fields. Numerical values of the load capacity and the approaching time are provided …

Go to article

An Application Of Space Syntax To Critical Working Space Analysis: The Case Of Building Construction, Li-Wen Wu, Sy-Jye Guo Oct 2014

An Application Of Space Syntax To Critical Working Space Analysis: The Case Of Building Construction, Li-Wen Wu, Sy-Jye Guo

Journal of Marine Science and Technology–Taiwan

The definition of critical space used in this paper is identical to the critical path definition employed in the critical path method (CPM). This definition implies that there is no extra floating space; thus, any conflict is expected to result in productivity loss. Space syntax is a theory developed to reveal the hidden interrelationships between spaces using architectural diagrams. Existing studies have indicated the potential for space syntax to identify critical spaces and to assist in reducing conflicts leading to productivity loss. However, there is not yet quantitative evidence demonstrating whether the quantitative parameters of relative convenience and relative control …

Go to article

A Residual-Norm Based Algorithm For Solving Determinate/Indeterminate Systems Of Non-Linear Algebraic Equations, Yung-Wei Chen Oct 2014

A Residual-Norm Based Algorithm For Solving Determinate/Indeterminate Systems Of Non-Linear Algebraic Equations, Yung-Wei Chen

Journal of Marine Science and Technology–Taiwan

In this paper, a residual-norm based algorithm (RNBA) is applied to solve determinate/indeterminate systems of nonlinear algebraic equations. The RNBA is derived from a manifold and defined in terms of a squared residual norm and a fictitious time variable, from which a robust iterative algorithm with either fixing or adjusting parameters can be obtained. Besides, some convergent indexes, such as manifold factor A0 and ratio of residual errors S, are defined to indicate the manifold attracting effect. Through the convergent indexes, the convergent mechanism of the RNBA displays a Hopf bifurcation when approximating the true solutions. Several numerical examples, including …

Go to article

Real-Time Load Balancing And Power Factor Correction Of Three-Phase, Four-Wire Unbalanced Systems With Dstatcom, Wei-Neng Chang, Kuan-Dih Yeh Oct 2014

Real-Time Load Balancing And Power Factor Correction Of Three-Phase, Four-Wire Unbalanced Systems With Dstatcom, Wei-Neng Chang, Kuan-Dih Yeh

Journal of Marine Science and Technology–Taiwan

This paper presents the design and implementation of a distribution-level static synchronous compensator (DSTATCOM) used for the real-time load compensation of three-phase, fourwire power distribution systems with unbalanced loads. First, use of the symmetrical components method derives a feedforward compensation scheme for the DSTATCOM. The system block diagram of the DSTATCOM is then built. A computer simulation is performed for preliminary verification. Finally, a hardware prototype is built using a TMS320C6711- based controller. Experimental results verify the functionality of the DSTATCOM.

Go to article

Flame Behavior Of Bifurcated Jets In A V-Shaped Bluff-Body Burner, Hsiu Feng Yang, Ching Min Hsu, Rong Fung Huang Oct 2014

Flame Behavior Of Bifurcated Jets In A V-Shaped Bluff-Body Burner, Hsiu Feng Yang, Ching Min Hsu, Rong Fung Huang

Journal of Marine Science and Technology–Taiwan

A plane fuel jet bifurcated into two streams of jets by a V-shaped bluff-body burner with co-flowing air streams was studied. The flame behavior, length, and temperature distributions of the bifurcated jets were experimentally examined. Flame behavior was characterized by flame visualization and instantaneous photograph. The flame length characteristics was obtained by using the long-exposure flame images. The temperatures distributions were measured by using a finewire thermocouple. Three characteristic flame modes were revealed—attached flame, transitional flame, and lifted flame. The flame length and width of the bifurcated jets increase with the increase of the Rec in fixed Rea. The length …

Go to article

Assessing Fishing Port Locations For Adaption Into Yacht Marinas In Taiwan, Ching-Min Yang, Chi-Chang Lai1, Long-Jing Wu, Jan-Jung Li Oct 2014

Assessing Fishing Port Locations For Adaption Into Yacht Marinas In Taiwan, Ching-Min Yang, Chi-Chang Lai1, Long-Jing Wu, Jan-Jung Li

Journal of Marine Science and Technology–Taiwan

As fishing resources gradually disappear, the original functions of fishing ports change. Modernizing traditional fishing ports is valuable for the fishing industry, tourism, and waterfront development. To determine suitable locations for such ports, an analytic hierarchy process and an interview survey were used to objectively analyze inputs from fishing port managers and yacht users. To establish additional yacht marinas in fishing ports, both groups attached importance to the “support of government and integration of policies” (rank and additive weight of manager : user = 1[0.185] : 2[0.119]). Therefore, inclusion of a complete and appropriate management mechanism must be emphasized during …

Go to article

Offshore Structural Dynamic Analysis Considering Soil-Structure Interaction By A Coupled Bem And Meshfree Method, Min-Chou Tsai, Hsien Hua Lee, Tinh Quoc Bui, Chuanzeng Zhang Oct 2014

Offshore Structural Dynamic Analysis Considering Soil-Structure Interaction By A Coupled Bem And Meshfree Method, Min-Chou Tsai, Hsien Hua Lee, Tinh Quoc Bui, Chuanzeng Zhang

Journal of Marine Science and Technology–Taiwan

An investigation of dynamic offshore structure considering soil-structure interaction by a coupled approach based on boundary element and meshfree methods is presented. The moving Kriging interpolation is used for generating the shape functions because of possessing the Kronecker delta property, which makes easier in imposing the essential boundary conditions. The governing elastodynamic equations are transformed into a standard weak formulation. It is then discretized into a meshfree system of time-dependent equations, which are solved by the standard implicit Newmark time integration scheme. Numerical examples illustrating the applicability and effectiveness of the proposed method are presented and discussed in details. A …

Go to article

Load Modeling Study Using Measurement Data For Taiwan Power System, Chung-Liang Chang, Pei-Hwa Huang Oct 2014

Load Modeling Study Using Measurement Data For Taiwan Power System, Chung-Liang Chang, Pei-Hwa Huang

Journal of Marine Science and Technology–Taiwan

he modern power system is an integrated complex dynamic system. Due to its scale and complexity, the power system operation and control heavily rely on numerical simulations based on power system models which includes load models. It has been observed that using different load models in the power system simulation may produce quite different, and even contradictory simulation results. Although the importance of load modeling on system dynamics has been well known, load modeling is still a very challenging problem. Thus, there remains a strong necessity for the development of an accurate dynamic load model for power system dynamic analysis …

Go to article

Boundary Knot Method Solution Of Helmholtz Problems With Boundary Singularities, De-Jian Shen, Ji Lin, Wen Chen Aug 2014

Boundary Knot Method Solution Of Helmholtz Problems With Boundary Singularities, De-Jian Shen, Ji Lin, Wen Chen

Journal of Marine Science and Technology–Taiwan

This paper proposes a boundary knot method (BKM) formulation in conjunction with the singularity subtraction technique to solve Helmholtz problems with boundary singularities. The solution breaks down into the singular solution and the regular solution. The singular solution is derived analytically and satisfies the governing equation and the corresponding boundary conditions containing singularities. Then the regular solution is approximated by the BKM. Numerical results demonstrate the accuracy and efficiency of the proposed technique.

Go to article

Behaviors Of Large-Scale Driven Pc Piles, Shih-Tsung Hsu Aug 2014

Behaviors Of Large-Scale Driven Pc Piles, Shih-Tsung Hsu

Journal of Marine Science and Technology–Taiwan

This study developed a numerical method for evaluating ground movements while a pile is being driven and obtained a comprehensive load-displacement curve for a driven pile. The tested pile exhibited a larger scale than those tested in previous studies, and was penetrated into a considerable depth of the stratum. Numerical results revealed that both the ground movement and residual force caused by the pile driving was able to be analyzed using the proposed numerical procedure. Although the load applied to the tested piles differed from that determined by numerically analyzing incremental pile displacement, the load-displacement behavior of the piles calculated …

Go to article

Optimization Of Electrical Discharge Machining Parameters For Niti Shape Memory Alloy By Using The Taguchi Method, Saeed Daneshmand, Ehsan Farahmand Kahrizi, Ali Akbar Lotfineyestanak, Vahid Monfared Aug 2014

Optimization Of Electrical Discharge Machining Parameters For Niti Shape Memory Alloy By Using The Taguchi Method, Saeed Daneshmand, Ehsan Farahmand Kahrizi, Ali Akbar Lotfineyestanak, Vahid Monfared

Journal of Marine Science and Technology–Taiwan

Electrical discharge machining (EDM) is among the most essential nontraditional machining processes. Material removal rate (MRR) and surface roughness are the two main parameters applied in this method. A desired surface roughness can be achieved at the maximal MRR by selecting the optimal input parameters. Because of the mechanical properties and hardness of shape-memory nickel titanium (NiTi) alloy, material can be removed using an EDM method. NiTi alloy is widely used in marine science and aerospace industries. Surface roughness is a critical parameter affecting the machining of this alloy. This study examined the effect the input parameters (pulse current, gap …

Go to article

Added Mass Computation For Control Of An Open-Frame Remotely-Operated Vehicle: Application Using Wamit And Matlab, You-Hong Eng, Cheng-Siong Chin, Michael Wai-Shing Lau Aug 2014

Added Mass Computation For Control Of An Open-Frame Remotely-Operated Vehicle: Application Using Wamit And Matlab, You-Hong Eng, Cheng-Siong Chin, Michael Wai-Shing Lau

Journal of Marine Science and Technology–Taiwan

In this paper, numerical modeling and testing of a complexshaped remotely-operated vehicle (ROV) are shown. The paper emphasizes on systematic modeling of hydrodynamic added mass using computational fluid dynamic software WAMITTM on the open frame ROV that is not commonly applied in practice. From initial design and prototype testing, a small-scale test using a free-decaying experiment is used to verify the theoretical models obtained from WAMITTM. Simulation results have shown to coincide with the experimental tests. The proposed method is able to determine the hydrodynamic added mass coefficients of the open frame ROV.

Go to article

Geometric Solution In Progressive Collapse Analysis Of Hull Girder, Ertekin Bayraktarkatal, Gökhan Tansel Tayyar Aug 2014

Geometric Solution In Progressive Collapse Analysis Of Hull Girder, Ertekin Bayraktarkatal, Gökhan Tansel Tayyar

Journal of Marine Science and Technology–Taiwan

This paper presents a calculation model for stiffened plates to determine the ultimate strength of ship hull girders from their curvatures using a geometrical approach. The present study employed Smith’s method, in which the cross-section is divided into smaller elements consisting of a stiffener(s) and attached plating. The strength of beam-columns and stiffened plates was obtained using an iterative numerical approach. The deflection curve was evaluated using the curvature values directly instead of by solving differential equations. The deflection curve was taken as an assembly of chains of circular arcs. The ultimate strength of the hull girder of a 1/3 …

Go to article

Intelligent Dynamic Acquisition Learning Fuzzy Modeling Systems Design, Hsuan-Ming Feng, Ching-Yi Chen Aug 2014

Intelligent Dynamic Acquisition Learning Fuzzy Modeling Systems Design, Hsuan-Ming Feng, Ching-Yi Chen

Journal of Marine Science and Technology–Taiwan

Secretary General, Taiwan Group on Earth Observations, Taiwan, R.O.C

Go to article

Reversing Sensitization Of Naturally Exfoliated 5456-H116 Aluminum Alloys, Ren-Yu Chen, Cheng-Chyuan Lai Aug 2014

Reversing Sensitization Of Naturally Exfoliated 5456-H116 Aluminum Alloys, Ren-Yu Chen, Cheng-Chyuan Lai

Journal of Marine Science and Technology–Taiwan

5456-H116 Al-Mg alloy has been broadly used in the U.S. Navy in order to meet the demand of reducing ship hull weight while considering high specific strength, corrosion resistance, and weldability. A particular concern of these alloy is sensitization, which causes it to be sensitized when highly anodic β phase (Al3Mg2) is precipitated at grain boundaries especially in service exceeding 65~200°C, leading to intergranular corrosion (IGC), exfoliation and stress corrosion cracking (SCC). This study investigated the reversal of sensitization of a naturally exfoliated 5456-H116 alloy plate by planned heating treatment with a short exposure to 250°C. The properties of sensitized …

Go to article

Robust Adaptive Motion Control With Environmental Disturbance Rejection For Perturbed Underwater Vehicles, Hamid Reza Koofigar Aug 2014

Robust Adaptive Motion Control With Environmental Disturbance Rejection For Perturbed Underwater Vehicles, Hamid Reza Koofigar

Journal of Marine Science and Technology–Taiwan

This paper addresses the motion control problem of autonomous underwater vehicles (AUVs) perturbed by unknown hydrodynamic coefficients, unmodelled dynamics and environmental disturbances. The proposed algorithm consists of an adaptive subcontroller to tackle the parametric uncertainties and a robust term to vanish the effects of unstructured uncertainties and disturbances. The resulting robust adaptive controller ensures the convergence of tracking error, without any assumption on the upper bound of perturbations in the design procedure. The closed loop stability is shown, using the Lyapunov stability theorem, and verified by various simulations.

Go to article

First Prev Next Last