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1993

Journal of Marine Science and Technology

Articles 1 - 11 of 11

Full-Text Articles in Engineering

Effects Of Anisotropy On The Hydrogen Induced Fatigue Crack Propagation Of A Banded Ferrite/Pearlite Steel, L. Tau, S.L.I. Chan, C.S. Shint Jun 1993

Effects Of Anisotropy On The Hydrogen Induced Fatigue Crack Propagation Of A Banded Ferrite/Pearlite Steel, L. Tau, S.L.I. Chan, C.S. Shint

Journal of Marine Science and Technology

The fatigue crack propagation (FCP) properties of AISI 4130 steel plates with a ferrite/pearlite (F/P) banded structure were evaluated both in air and electrolytic hydrogen charging environments. To understand the combined effects of hydrogen, directions of banding and elongated non-metallic inclusions on the FCP, specimens with six different orien- tations relative to the rolling direction were sampled and charged with hydrogen. When tested in air, the result reveals that the crack plane as related to the direction of banding, and the local stress concentration induced by elongated inclusions, largely affected the FCP rate. It also shows that the relative dominance …

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Numerical Study Of Spray Flame Characteristics, C.Y. Lin Jun 1993

Numerical Study Of Spray Flame Characteristics, C.Y. Lin

Journal of Marine Science and Technology

A numerical method was considered to calculate spray flame structure and emissions characteristics. The turbulence fluctuation was predicted using k-e-g and algebraic mixing-length-hypothesis (mlh) turbulence models. The numerical method was evaluated using a set of available experimental data. It is shown that this theoretical model predicts the data well in the near nozzle region and the predictions improve quantitatively along the axial distance. In comparing the turbulence models, the k-e-g model provides a better result for the varying-density flow of spray combustion.

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Vibration Suppression Of Beam Structures Traversed By Multiple Moving Loads Using A Damped Absorber, Y.H. Lin, C.H. Cho Jun 1993

Vibration Suppression Of Beam Structures Traversed By Multiple Moving Loads Using A Damped Absorber, Y.H. Lin, C.H. Cho

Journal of Marine Science and Technology

This paper deals with the dynamic analysis of a simply supported beam subjected to multiple discrete and distributed moving loads. Resonant vibration is observed for the support beam traversed by multiple discrete moving loads. A practical scheme is applied to reduce the excessive beam vibration to an acceptable range by using a damped absorber attached at the beam center. Lagrange's equation is used to formulated the system governing equation and Laplace transformation is applied to derive the dynamic responses for both the beam and the absorber, Various design parameters, such as the mass ratio, the tuning ratio, and the damping …

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Pitting Of Fe-Mn-Al Alloys In Nacl Solution, M Ruscak, T.P Perng Jun 1993

Pitting Of Fe-Mn-Al Alloys In Nacl Solution, M Ruscak, T.P Perng

Journal of Marine Science and Technology

the increase of ferrite content. However, the nearly ferritic alloy showed much better passivation behavior, presumably due to the addition of 6% Cr.In aerated solution, no or very small passive region was observed. From the immersion test, the general corrosion was found to be minor. Pitting corrosion was the primary corrosion except for the ferritic alloy. The pits were found more frequently in the ferrite phase or at the interface between the ferrite and austenite phases.

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Dehumidification Of Air Flowing In The Entrance Region Of A Channel, R.H. Yeh, W.H. Huang Jun 1993

Dehumidification Of Air Flowing In The Entrance Region Of A Channel, R.H. Yeh, W.H. Huang

Journal of Marine Science and Technology

The heat transfer and dehumidifying characteristics in the entrance region of the parallel plates are studied. Two-dimensional boundary layer equations are solved numerically to obtain the mass concentration for the air-vapor mixture in the inlet of a channel. A simple experiment is conducted to verify the theory. The ratio of the flow length to plate spacing is chosen to be 20/3. It shows that the average total and mass transfer colburn j-factors obtained from experimental data are higher than those of numerical analysis. Finally, the relationships between experimental data and numerical results are acquired to facilitate the prospective design of …

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Identification Of Whirling Motions By Phase Unwrapping Technique, Rong-Juin Shyu Jun 1993

Identification Of Whirling Motions By Phase Unwrapping Technique, Rong-Juin Shyu

Journal of Marine Science and Technology

A method for identifying the whirling motion of a rotating shaft has been developed. This method is based on the phase unwrapping of two strain gages' signals. These two stain gages are being attached ninety degrees apart onto the rotating shaft thus observe the shaft's motion in a rotating coordinate with speed the same as that of the shaft. With such arrangement of the strain gages, the whirling motions of the shaft can be identified provided that the rotation speed of the shaft is known. These whirling motions include forward whirl and backward whirl. Equations are given to show how …

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Second Law Analysis On Ejection Cooling System, S.P. Liaw, Y.H. Chang Jun 1993

Second Law Analysis On Ejection Cooling System, S.P. Liaw, Y.H. Chang

Journal of Marine Science and Technology

Ejection cooling system is analyzed by the second law of thermodynamics in this study. It is mainly consisted of a boiler, an ejector, an expansion device, a condenser, and an evaporator. Special focus is stressed on the variation of exergy in each component. The working refrigerant received exergy from boiler and pump and cons umed in other parts of the system. The coefficients of performance based on both the first and the second laws are computed respectively and thus the changes of energy and exergy in each component of the system can be readily understood. In addition, the boiler temperature, …

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Analysis And Simulation Of Solidification For Phase Change Materials In A Cylindrical Container, H.C. Tien, J.S. Chang Jun 1993

Analysis And Simulation Of Solidification For Phase Change Materials In A Cylindrical Container, H.C. Tien, J.S. Chang

Journal of Marine Science and Technology

The objective of this paper is to study the solidification problem of the phase change materials (PCM) in a thick-walled cylindrical container. Through varying each controlling parameter such as the thermophysical properties of wall (mold), wall thickness, aspect ratio of the container, initial temperature of PCM and the external cooling conditions, etc., the effect of each parameter on the solidification process is shown clearly. By knowing how a thick wall interacts with such a phase change phenomenon, it is therefore possible to well control the solidification process and also to improve the solid structure formed. In this study, convective boundary …

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Formation Of Amorphous Cu-Zr Alloy Powder By Mechanical Alloying, T.R. Chen, P.Y. Lee Jun 1993

Formation Of Amorphous Cu-Zr Alloy Powder By Mechanical Alloying, T.R. Chen, P.Y. Lee

Journal of Marine Science and Technology

Amorphous Cux Zr100-x alloy powder has been synthesized in the range 20 ≦ x ≦ 80 by mechanical alloying mixtures of Cu and Zr powders. This range is larger than amorphous alloys produced by the vaporquenching technique. A mixture of amorphous and crystalline phases formed at the compositions of Cu10Zr90 and Cu90Zr10. Amorphous CuxZr100-x alloy powder also has been synthesized in the range 20 ≦ X ≦ 60 by mechanical alloying mixtures of intermetallic compound Cu9Zr2 and CuZr2 powders. The temperature and activation energy for crystallization of the MA Cu-Zr amorphous powders are higher than that for vaporquenched samples. The …

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Aluminum Electrodeposition From Room Temperature Molten Alcl3-Bpc Salt Bath, C.C. Yang, C.P. Chang Jun 1993

Aluminum Electrodeposition From Room Temperature Molten Alcl3-Bpc Salt Bath, C.C. Yang, C.P. Chang

Journal of Marine Science and Technology

The characteristics of aluminum electrodeposited layer from an ambient temperature molten salt were discussed in this study. The experimental results indicated that it is possible to carry out aluminum electrodeposition on the surface of brass and stainless steel when binary AlCI3-8P C molten electrolysis were used. The morphology of the components, characteristics and images can be detected by SEM, Auger Analysis, X-ray diffraction analysis and electrochemical polarization curves. The denser and more adhesive electrodeposited aluminum layer can be achieved by chosing proper electrolyte components (AlCI3: BPC-acidic salt bath), current forms (D.C./pulse), current density, electrolytic time and other pretreatment. In addition, …

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Breaking Wave Spectrum And Set-Down Set-Up In Shallow Water, W.H. Yang Jun 1993

Breaking Wave Spectrum And Set-Down Set-Up In Shallow Water, W.H. Yang

Journal of Marine Science and Technology

To study the mean water surface in the shallow water, it is necessary to compute the wave set-up and set-down of random waves on the surf zone. Therefore, the breaking wave spectra and radiation stress must be calculated from a wide-band breaking wave model. In this study, we extend the breaking wave spectrum model (Yang, 1991) by using the Wallops spectrum in the deep water. The Wallops spectrum is based on wave dynamics theoretical analysis and no empirical coefficients to be determined by the users. It also contents correct energy (Huang et al., 1981). The breaking wave spectra, radiation stress, …

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