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Articles 361 - 390 of 445
Full-Text Articles in Mechanical Engineering
An Improvement Of Wave Refraction-Diffraction Effect In Swan, Aw-Guei Lin
An Improvement Of Wave Refraction-Diffraction Effect In Swan, Aw-Guei Lin
Journal of Marine Science and Technology–Taiwan
SWAN, a wind wave model, has been modified to take into account wave refraction-diffraction effects from the extended mild-slope equation when wind waves pass through a extremely uneven sea bottom in the presence of current. In our modified model, the diffraction correction parameter introduced by Holthuijsen et al. [10] has been adjusted to better predict the combined effect of the higher-order bottom effect, wave-bottom interaction and wave-current interaction. After a preliminary analysis, the influence of the correction parameter is discussed, and a comparison is made between the original and the new phase-decoupled versions of SWAN through some typical examples of …
An Experimental Study Of Regular Long Crested Waves Over A Crescent Type Shoal, Wen-Kai Weng, Jaw-Guei Lin, Chun-Sien Hsiao
An Experimental Study Of Regular Long Crested Waves Over A Crescent Type Shoal, Wen-Kai Weng, Jaw-Guei Lin, Chun-Sien Hsiao
Journal of Marine Science and Technology–Taiwan
Converting the ocean wave energy into electric power is one possibility of the development of alternative and nonpolluting sources of energy. Many researches concerning converters and their converting efficiency of wave power were developed and discussed in the last years. However, converting wave energy into electric power does not only depend upon converting system but condition of sea state essentially. A calm sea state with lower wave energy is difficult to drive converting device working and is unable to satisfy the minimum economical requirement. Unfortunately, wave heights in the sea state around Taiwan are mostly too smaller to extract the …
Criteria For The Initiation Of Modes Of Response Of A Caisson Subjected To A Breaking Wave Force, Jaw Guei Lin, Chi Chao David Tung
Criteria For The Initiation Of Modes Of Response Of A Caisson Subjected To A Breaking Wave Force, Jaw Guei Lin, Chi Chao David Tung
Journal of Marine Science and Technology–Taiwan
This paper concerns problems of a caisson subjected to a breaking wave force: (1) what are the possible modes of response and (2) the conditions initiate into these modes. These two questions have not been studied. The objective of this paper is to answer these two questions. However, the actual response of a caisson that takes place in each mode is not addressed in this study. A caisson placed on a horizontal frictional base, subjected to a concentrated horizontal force of short duration, applied to the seaward side face of the caisson and accompanied by a corresponding uplift force on …
Carbonation Service Life Prediction Of Existing Concrete Viaduct/Bridge Using Time-Dependent Reliability Analysis, Ming-Te Liang, Ran Huang, Shen-Ann Fang
Carbonation Service Life Prediction Of Existing Concrete Viaduct/Bridge Using Time-Dependent Reliability Analysis, Ming-Te Liang, Ran Huang, Shen-Ann Fang
Journal of Marine Science and Technology–Taiwan
This paper examines the predicted carbonation life of an existing concrete viaduct/bridge in the atmospheric environment based on probability and reliability indices. The probability is dependent upon the carbonation rate, carbonation remainder, concrete quality, and concrete cover. The carbonation life is defined as the service life of reinforced concrete (RC) or prestressed concrete (PC) structure at the beginning of time of steel corrosion when concrete cover surfers from carbonation and loses the protection function to steel. The carbonation life is equivalent to the initiation time of corrosion of reinforcement. Both the Chorng-ching viaduct and Wannfwu bridge were offered as illustrative …
Effects Of Non-Newtonian Couple Stresses On The Dynamic Characteristics Of Wide Rayleigh Step Slider Bearings, Jaw-Ren Lin, Li-Ming Chu, Wei-Liang Liaw
Effects Of Non-Newtonian Couple Stresses On The Dynamic Characteristics Of Wide Rayleigh Step Slider Bearings, Jaw-Ren Lin, Li-Ming Chu, Wei-Liang Liaw
Journal of Marine Science and Technology–Taiwan
To provide more information in fluid-film lubricated bearings, the effects of non-Newtonian couple stresses on the dynamic characteristics of Rayleigh step slider bearings have been presented in this paper. According to the results, the effects of non-Newtonian couple stresses signify an improvement in the bearing characteristics. Comparing with the Newtonian-lubricant Rayleigh step bearing, the nonNewtonian couple stress effects provide an increase in the steady load-carrying capacity, the dynamic stiffness coefficient and the dynamic damping coefficient, as well as a reduction in the steady volume flow rate required. In order to guide the use of the present study, a numerical example …
Fuzzy Statistical Refinement For The Forecasting Of Tenders For Roadway Construction, Jeng-Wen Lin, Cheng-Wu Chen, Ting-Chang Hsu
Fuzzy Statistical Refinement For The Forecasting Of Tenders For Roadway Construction, Jeng-Wen Lin, Cheng-Wu Chen, Ting-Chang Hsu
Journal of Marine Science and Technology–Taiwan
Due to market competition, construction companies often place low bids when tenders are invited for domestic public construction projects. Over-competition can lead to vicious price wars to win a tender, which can in turn seriously affect the quality of construction. This study aims to establish an accurate Taiwan based model for the forecasting of the tendered price for roadway construction. This model is designed to assist the public sector to determine what would be a reasonable reserve price or award price. In order to ensure accurate predictions, a data classification system is established using fuzzy set theory. For each category …
An Arc Code To Predict The Thermal Crack Of Welded Sample, Je-Ee Ho
An Arc Code To Predict The Thermal Crack Of Welded Sample, Je-Ee Ho
Journal of Marine Science and Technology–Taiwan
In this study, a numerical code with enthalpy method in upwind scheme is proposed to estimate the distribution of thermal stress in the molten pool, which is primarily determined by the type of the input power and travel speed of heating source. To predict the cracker deficit inside the workpiece, a simulated program satisfying the diagonal domination and Scarborough criterion provides a stable iteration. Meanwhile, an experimental performance, operated by robot arm “DR-400” to provide a steady and continuous arc welding, was also conducted to verify the simulated result. By surveying the consistence of molten pool bounded by contrast shade …
Rust-Expansion-Crack Service Life Prediction Of Existing Reinforced Concrete Bridge/Viaduct Using Time-Dependent Reliability Analysis, Ming-Te Liang, Jiang-Jhy Chang, Han-Tung Chang, Chi-Jang Yeh
Rust-Expansion-Crack Service Life Prediction Of Existing Reinforced Concrete Bridge/Viaduct Using Time-Dependent Reliability Analysis, Ming-Te Liang, Jiang-Jhy Chang, Han-Tung Chang, Chi-Jang Yeh
Journal of Marine Science and Technology–Taiwan
It is necessary to develop a calculation method to help in the making of feasible, reliable, and serviceable predictions for the service lives of bridge or viaduct structures. This article presents the basis for doing rust-expansion-crack service life predictions for existing reinforced concrete (RC) bridges and viaducts in chloride-laden environments based on timedependant reliability modeling due to the corrosion of steel in concrete. The corrosion process has three stages, the initiation (diffusion or carbonation) time (ti = tc), the depassivation time (tp), and the propagation (corrosion) time (tcorr). The rustexpansion-crack service lives (tcr) of existing RC bridges or viaducts can …
Studies Of The Effect Of Diffusion-Induced Chloride Binding On Chlorination Life Predictions For Existing Reinforced Concrete Bridges, Ming-Te Liang, Jiang-Jhy Chang, Tung-Wei Yu
Studies Of The Effect Of Diffusion-Induced Chloride Binding On Chlorination Life Predictions For Existing Reinforced Concrete Bridges, Ming-Te Liang, Jiang-Jhy Chang, Tung-Wei Yu
Journal of Marine Science and Technology–Taiwan
The chloride ions diffusion is one of important factors of corrosion of reinforced concrete (RC) structures. The total chloride concentration penetrated into concrete can be expressed as the sum of bound and free chloride concentrations. The principal purpose of this paper is to study the chlorination life prediction of existing RC bridges due to chloride binding effect. The investigation method is that the no binding, linear binding, Langmuir and Freundlich adsorption isotherms are substituted into the analytical solutions of linear (diffusivity D = constant) and non-linear (D ≠ constant) diffusion equations associated with initial and boundary conditions, respectively. The chlorination …
Study On The Seismic Behavior Of Self-Anchored Suspension Bridges, Wen-Liang Qiu, Chang-Huan Kou, Chin-Sheng Kao, Shih-Wei Ma, Jiun Yang
Study On The Seismic Behavior Of Self-Anchored Suspension Bridges, Wen-Liang Qiu, Chang-Huan Kou, Chin-Sheng Kao, Shih-Wei Ma, Jiun Yang
Journal of Marine Science and Technology–Taiwan
The suspension bridge has a beautiful structural shape and an excellent spanning ability. The self-anchored suspension bridge has its main cables anchored directly on the two ends of the main girders, saving construction costs and time incurred during the anchorage construction of an earth-anchored suspension bridge. However, the feasibility of a self-anchored suspension bridge in a strong earthquake zone and the use of dampers to reduce seismic responses have yet to be fully investigated. Using the Yellow-River Road Bridge in Mainland as an example, this study sets out to analyze and investigate a series of seismic responses of a self-anchored …
A Manifold-Based Exponentially Convergent Algorithm For Solving Non-Linear Partial Differential Equations, Chein-Shan Liu
A Manifold-Based Exponentially Convergent Algorithm For Solving Non-Linear Partial Differential Equations, Chein-Shan Liu
Journal of Marine Science and Technology–Taiwan
For solving a non-linear system of algebraic equations of the type: Fi(xj) = 0, i, j = 1, …, n, a Newton-like algorithm is still the most popular one; however, it had some drawbacks as being locally convergent, sensitive to initial guess, and time consumption in finding the inversion of the Jacobian matrix ∂Fi /∂xj. Based-on a manifold defined in the space of (xi, t) we can derive a system of non-linear Ordinary Differential Equations (ODEs) in terms of the fictitious time-like variable t, and the residual error is exponentially decreased to zero along the path of x(t) by solving …
Design Of Planning Level Ship Product Model For Ship Initial Design, Sungchul Shin, Soon-Sup Lee, Jong-Kap Lee, Kyung-Ho Lee
Design Of Planning Level Ship Product Model For Ship Initial Design, Sungchul Shin, Soon-Sup Lee, Jong-Kap Lee, Kyung-Ho Lee
Journal of Marine Science and Technology–Taiwan
This paper introduces a design of planning level ship product model (called SPPM hereinafter) based on ISO 10303 Standard for The Exchange of Product Model data (STEP). For the design of this model, the information modeling methodologies such as Integration Definition (IDEF) methods and Unified Modeling Language (UML) were reviewed, and a hybrid method was established. By using this method, ship initial design process was analyzed, and STEP-based information model and class libraries for SPPM were defined. For the data structure of this model, the shipbuilding Application Protocols (AP215, AP216 and Ship Common Model) of STEP were investigated and utilized …
Constructing The Comprehensive Subsurface Structure Of Lanyang Plain, Chih-Hao Hsu, Sao-Jeng Chao, Shuh-Gi Chern, Howard Hwang
Constructing The Comprehensive Subsurface Structure Of Lanyang Plain, Chih-Hao Hsu, Sao-Jeng Chao, Shuh-Gi Chern, Howard Hwang
Journal of Marine Science and Technology–Taiwan
This study presents an integral approach to construct a comprehensive subsurface structure of Lanyang Plain. It is well known that geophysicists and engineers use different techniques to investigate the subsurface structure, and each of these techniques has its own advantages. Therefore, in this study, the excellent results from these two fields are selected and combined to provide a comprehensive profile of the subsurface structure of Lanyang Plain. In this study, the subsurface information on nine recording stations and digital boundary lines of Lanyang Plain based on the digital geologic map published by the Central Geological Survey are utilized to create …
Slamming Induced Dynamic Response Of A Floating Structure, Mohammad Ali Lotfollahi-Yaghin1, Mehdi Rastgar, Hamid Ahmadi
Slamming Induced Dynamic Response Of A Floating Structure, Mohammad Ali Lotfollahi-Yaghin1, Mehdi Rastgar, Hamid Ahmadi
Journal of Marine Science and Technology–Taiwan
Study of the slamming phenomenon is one of the most important branches of the floating structure dynamics. Experimental study of the floating structure dynamics can be very expensive because it requires a long wave flume and a moving model. Hence, numerical methods are considered to be very useful and efficient tools for modeling and dynamic analysis of floating structures. In the present paper, slamming induced impulsive loads are investigated firstly. Afterwards, dynamic response of a barge under the slamming excitation is studied, and the natural frequencies and mode shapes are determined, using the FE software package, ANSYS. Critical cross sections …
Transient Response Of Sloshing Fluid In A Three Dimensional Tank, Chih-Hua Wu, Bang-Fuh Chen
Transient Response Of Sloshing Fluid In A Three Dimensional Tank, Chih-Hua Wu, Bang-Fuh Chen
Journal of Marine Science and Technology–Taiwan
Sloshing waves in moving tanks have been studied numerically, theoretically and experimentally in the past several decades. Most reported studies have been for tanks excited by forcing motion in a limited number of directions and with fixed excitation frequencies throughout the forcing. In the present study, a time-independent finite difference method is used to simulate fluid sloshing in the three-dimensional tanks with arbitrary depths and the tanks are subject to a range of excitation frequencies with motions that exhibit multiple degrees of freedom. The developed numerical scheme is verified by rigorous benchmark tests, and the advantage and efficiency of the …
Numerical Study On Significance Of Wind Action On 2-D Freak Waves With Different Parameters, Shiqiang Yan, Qingwei Ma
Numerical Study On Significance Of Wind Action On 2-D Freak Waves With Different Parameters, Shiqiang Yan, Qingwei Ma
Journal of Marine Science and Technology–Taiwan
This paper presents a numerical study on how the significance of wind action differs when varying the wave parameters. The quasi arbitrary Lagrangian-Eulerian finite element method (QALE-FEM) is used for this purpose. An improved model for wind-excited pressure and wind-driven current, which is recently developed by the authors of this paper [27], is coupled with the QALE-FEM. Many cases involving freak waves with different focusing time/point and frequency ranges under the action of winds are investigated. The results show that the significance of wind actions on freak waves strongly depends on the focusing time, the focusing point and the frequency …
Semi-Analytical Solution For Radiation Of A Hollow Sphere With An Opening Hole In Finite Depth, Man-Sheng Dong, Guo-Ping Miao, Ju Fan, Ren-Chuan Zhu
Semi-Analytical Solution For Radiation Of A Hollow Sphere With An Opening Hole In Finite Depth, Man-Sheng Dong, Guo-Ping Miao, Ju Fan, Ren-Chuan Zhu
Journal of Marine Science and Technology–Taiwan
An investigation is conducted on radiation of a submerged hollow sphere with an opening hole in finite water depth in this article. Based on the linear theory, the method of multipole expansions is used to obtain the fluid velocity potential in the form of double series of the associated Legendre functions with the unknown coefficients of an infinite set. In terms of the body surface boundary condition and the matching condition between the inner and outer flows at the hole, the complex matrix equations for the coefficients of the series are established. The infinite sets of matrix equations are solved …
Aerodynamic Performance And Shedding Characteristics On A Swept-Back Wing, Shun-Chang Yen
Aerodynamic Performance And Shedding Characteristics On A Swept-Back Wing, Shun-Chang Yen
Journal of Marine Science and Technology–Taiwan
A NACA 0012 finite swept-back wing with a sweep-back angle of 15° was utilized to investigate the effects of angle of attack (α) and the chord Reynolds number (Rec) on the vortex shedding and aerodynamic coefficients. A hot-wire anemometer was applied to measure the vortex-shedding frequency. The projected Strouhal number (Std) at various angles of attack was determined and discussed. The relationship between Std and α is regressed as: Std = -0.0008 α + 0.209, for 22° < α < 90°. Four characteristic surface-flow patterns: separation bubble, leading-edge bubble, bubble burst, and turbulent separation were classified by changing α and Re. The behavior of surface-flow structures significantly affects the lift, drag, and moment coefficients. The lift coefficient (CL) increases with α in the separation bubble and leading-edge bubble regimes. The maximum increase rate of CL with respect to α (d(CL)/dα) is 1.52 π/rad. Occurring in the leadingedge bubble regime. However, the maximum increase rate of drag coefficient (CD) with respect to α (d(CD)/dα) is 0.49 π/rad. Occurring in the bubble-burst regime. The steep-drop of moment coefficient at stall in the unswept-wings is not observed in the swept-back wings.
Hydrogen Absorption/Desorption In A Metal Hydride Reactor Accounting For Varied Effective Thermal Conductivity, Chih-Yuan Wang, Hwa-Chong Tien, San-Der Chyou, Nang-Nong Huang, Shing-Hoa Wang
Hydrogen Absorption/Desorption In A Metal Hydride Reactor Accounting For Varied Effective Thermal Conductivity, Chih-Yuan Wang, Hwa-Chong Tien, San-Der Chyou, Nang-Nong Huang, Shing-Hoa Wang
Journal of Marine Science and Technology–Taiwan
This paper investigates the effect of varied effective thermal conductivity on the hydrogen absorption/desorption in a metal hydride (MH) reactor. The effective thermal conductivity of a metal hydride bed was measured by performing steady-state experiment and then compared with the results obtained by employing an existing model. Good agreement was found. Next, numerical simulation on the performance of hydrogen absorption/desorption of the MH reactor was conducted by assuming either varied or constant effective thermal conductivity. Corresponding hydrogen absorption/desorption experiment was performed for comparison. It was found that numerical simulation accounting for varied effective thermal conductivity agrees with the experimental data …
Dislocation Substructures Of Interstitial-Free Steel Subjected To Low Cycle Fatigue At Various Strain Amplitude, Shih-Wei Mao, Wen-Chun Lo, Hsing-Lu Huang, New-Jin Ho
Dislocation Substructures Of Interstitial-Free Steel Subjected To Low Cycle Fatigue At Various Strain Amplitude, Shih-Wei Mao, Wen-Chun Lo, Hsing-Lu Huang, New-Jin Ho
Journal of Marine Science and Technology–Taiwan
The aim of this wok is to study the fatigue properties in relation to the microstructures of interstitial-free (IF) steel, a representative of body center cubic (BCC) materials, subjected to low cycle periodic stress. In order to compare the grain size effect on dislocation development, we used samples of two distinctive grain sizes, 70 µm and 210 µm, prepared by different thermo-mechanical processes. We found (1) there was an initial softening when the stain amplitude was lower than 1.6% and the microstructure of the fatigued samples are cellular independent of the grain sizes and the amplitude of strain. (2) A …
Deformation Of Rolling Shutters Under Uniform Wind Pressure, Nan-Nong Huang, San-Ming Chang
Deformation Of Rolling Shutters Under Uniform Wind Pressure, Nan-Nong Huang, San-Ming Chang
Journal of Marine Science and Technology–Taiwan
In this study, a model is developed to analyze the structural behaviors of rolling shutters subjected to wind pressure. In the current shutter theory, the elastic properties of shutters are characterized by two bending rigidities, which can be determined from the flexural tests of slats and shutters. Close form solutions can be obtained for the deflection of shutters with two opposite simply supported edges. To assess the validity of the present theory, rolling shutters with various sizes and supporting conditions under various magnitudes of loadings are tested. It is noted that the deflections and axial displacements based on the current …
Laminar Flow Past An Oscillating Circular Cylinder In Cross Flow, Pham Anh-Hung, Lee Chang-Yeol, Seo Jang-Hoon, Chun Ho-Hwan, Kim Hee-Jung, Hyun-Sik Yoon, Dong-Woo Park, Il-Ryong Park
Laminar Flow Past An Oscillating Circular Cylinder In Cross Flow, Pham Anh-Hung, Lee Chang-Yeol, Seo Jang-Hoon, Chun Ho-Hwan, Kim Hee-Jung, Hyun-Sik Yoon, Dong-Woo Park, Il-Ryong Park
Journal of Marine Science and Technology–Taiwan
The present study numerically investigates the twodimensional laminar flow past a circular cylinder forced to oscillate transverse to the free-stream. The numerical simulations are performed at a various range of cylinder oscillation frequency ranged between 0.8 and 1.2 of the natural vortex shedding frequency, and the oscillation amplitude extended up to 50% of the cylinder diameter at one Reynolds number of 185 showing the typical two-dimensional vortex shedding. The immersed boundary method is used to handle the oscillating cylinder in a rectangular grid system using the finite volume method. The primary vortex shedding frequency has the same value with the …
Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung
Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung
Journal of Marine Science and Technology–Taiwan
A fuzzy gain scheduling proportional controllers that exhibits the improved performance than the conventional linear fixed gain controller having input saturation is proposed in this paper. We proposed an adaptive anti-windup control system in which the gain of a proportional controller is dynamically tuned by a fuzzy PD system. The methodology employed in the analysis is based on the describing function (DF), which is determined the range of the universal discourse for the output of the fuzzy PD system. Other approaches are the linear quadratic regulator (LQR) method and combined back-calculation and generalized conditioning anti-windup. In this paper, a comparison …
Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung
Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung
Journal of Marine Science and Technology–Taiwan
The robust stability of Lur’e system with parametric uncertainty is studied through the Popov-Lyapunov approach. Robust stability bounds of such a system are presented. Since we avoid using norm forms and absolute values, the obtained stability bounds are less conservative. An example demonstrating the feasibility of our method is illustrated
Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang
Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang
Journal of Marine Science and Technology–Taiwan
This work analyzes non-Darcy flow and heat transfer in a vertical slot filled with a porous matrix. The left and right vertical boundaries of the porous system are maintained at higher and lower temperatures, respectively. The horizontal boundaries are assumed to be impermeable and insulated. The vertical boundaries are either completely impermeable, where free convection is induced, or partially permeable in a way to simulate the wall leakage in the building materials, where both air infiltration and free convection exist. The non-Darcy model, which includes the Brinkman and Forchheimer extensions along with the convection terms, is employed to describe the …
Labview-Based Fuzzy Controller Design Of A Lighting Control System, Mou-Lin Jin, Ming-Chun Ho
Labview-Based Fuzzy Controller Design Of A Lighting Control System, Mou-Lin Jin, Ming-Chun Ho
Journal of Marine Science and Technology–Taiwan
This paper describes how we design a lighting control system including hardware and software. Hardware includes light sensing circuit, control circuit, and 8255 expanding I/O circuit, PC, and bulb. Sensing circuit uses photo-resistance component to sense the environmental light and then transmit the signal of the lightness to the computer through an 8-bit A/D converter 0804. The control circuit applies reed relay in digital control way to adjust the variable resistor value of the traditional dimmer. Software incorporates LABVIEW graphical programming language and MATLAB Fuzzy Logic Toolbox to design the light fuzzy controller. The rule-base of the fuzzy logic controller …
Catamaran Motion Simulation Based On Moving Grid Technique, Ebrahim Jahanbakhsh, Roozbeh Panahi, Mohammad Saeed Seif
Catamaran Motion Simulation Based On Moving Grid Technique, Ebrahim Jahanbakhsh, Roozbeh Panahi, Mohammad Saeed Seif
Journal of Marine Science and Technology–Taiwan
General purpose software is developed to simulate 6-DoF fluid-structure interaction in two-phase viscous flow. It is a VoF-fractional step solver based on the finite-volume discretization which uses a boundary-fitted body-attached hexahedral grid as the motion simulation strategy. As an application, a high-speed planing catamaran is simulated in steady forward motion as well as in turning maneuver. Results are compared with the available data and good qualitative and quantitative agreements are achieved. Numerical schemes and the solution algorithm of the software are consistent and show a good capability to model highly nonlinear ship motions. It can be further developed to represent …
Kalman Filter Effective To Hydrologic Routing?, Yang-Liang Jeng, Rong-Che Chen, Chao-He Chang
Kalman Filter Effective To Hydrologic Routing?, Yang-Liang Jeng, Rong-Che Chen, Chao-He Chang
Journal of Marine Science and Technology–Taiwan
Intake-generated tumbling motion has been recently proposed to enhance the turbulence level during compression stroke to promote the combustion rate and reduce operation variations. This study is to investigate the quality of the tumbling motion, especially for the engine with a bowl-in-piston. To overcome the difficulties on the flow visualization caused by the high-speed motion of a real engine, a transparent water-analogy-simulation system is designed based on similarity analysis and fabricated to model the operation of an actual engine. Benchmark tests including the qualitative flow visualization and quantitative full-field measurements using a high-speed PIA system have been conducted to study …
Evaporation Effect In Nonlinear Penetration Of High Energy Beam Drilling, Je-Ee Ho, Chen-Lung Yen
Evaporation Effect In Nonlinear Penetration Of High Energy Beam Drilling, Je-Ee Ho, Chen-Lung Yen
Journal of Marine Science and Technology–Taiwan
Due to the inappropriate assumption with the neglect of evaporation effect in previous research, a linear penetration behavior with a significant deviation from the experimental result was usually proposed in the lower energy density region. To remedy the defect, the evaporation mass determined from the difference between the melting rate and flow expulsion by pressure difference is reconsider in this study. With a 2-D quasic-steady model based on the enthalpy theory, the uniform penetration velocity estimated from the Stefan boundary condition provides a special advantage in calculating efficiency. Meantime, the divergent iteration has been effectively avoided by setting up a …
Study On Mechanical Properties Of A356 Alloys Enhanced With Preformed Thixotropic Structure, Shueiwan H. Juang, Shyh-Ming Wu
Study On Mechanical Properties Of A356 Alloys Enhanced With Preformed Thixotropic Structure, Shueiwan H. Juang, Shyh-Ming Wu
Journal of Marine Science and Technology–Taiwan
A preformed A356 alloys with thixotropic structure (designated SSM-A356) was systematically studied on mechanical properties in order to establish the database for further investigations in forming and heat treatment. Because of the specific microstructure and characteristics, the heat treatment conditions of SSM-A356 were explored through the observations of microstructure and the measurement of micro-hardness. In the investigation of heat treatment, it was observed that the eutectic silicon was refined and spheroidized which is unlikely for conventional processing. The mechanical testing results showed that the yield and ultimate tensile strength of SSM-A356 were respectively around 115% and 34% greater than those …