Papers by Author: Te Hua Fang

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Authors: Chao Ming Lin, Te Hua Fang, Win Jin Chang
Abstract: This paper develops models for micro-fluid flow in tubular microchannels with uniform or varying cross-sections. The fluid flow is governed by the pressure drop, the capillary force, and the viscous force. The governing equation developed for the flow incorporates two geometry parameters, namely the cross-section perimeter, S, and the cross-section area, A. In a microchannel with a uniform cross-section, the governing equation reduces to a linear initial value problem which can be solved analytically. However, in the case of a varying cross-section, the two geometry parameters vary as a function of the flow front position, L, and the nonlinear initial value problem must be solved numerically. The computational models developed in this study will be able to provide accurate predictions of the micro-fluid flow behavior in microchannels with uniform or varying cross-sections.
Authors: Zheng Han Hong, Shun Fa Hwang, Te Hua Fang
Abstract: The mixing situation of Co atoms implanting onto Cu(001) substrate is investigated with regard to incident energy and substrate temperature by molecular dynamics. The results indicate that higher substrate temperature and/or incident energy will result in higher intermixing between the incident atoms and the substrate atoms. Furthermore, the value of the first peak of the radial distribution function (RDF) becomes lower and wider for the Co-Cu system as the substrate temperature and/or incident energy are increased.
Authors: Ming Yuan Chen, Zheng Han Hong, Te Hua Fang, Shao Hui Kang, Li Min Kuo
Abstract: Molecular dynamic simulation for Fe sliding on Fe substrate with textured surface is investigated in this work. The textured surfaces on sliding are discussed to elucidate the physics of friction at the small scale. The modified embedded-atom method many-body potential is modeled to describe the interaction of Fe-Fe atoms. We find that a textured surface can reduce the friction because the former can entrap wear particles, effectively reducing the contact area. In addition, the friction force increases almost linearly in the low sliding speed with the increasing of sliding speeds. However, the friction force decreased as the increasing speed exceeds the 300 m/s.
Authors: Wen Yang Chang, Te Hua Fang, Cheng Hong Syu
Abstract: Material characteristics of Zinc Oxide doped Al are investigated for microharvester. The microharvester include two parts, the first part is zigzag structures on silicon wafer using MEMS fabrication, and the second part is epitaxial ZnO with doping Al nanostructures on ITO glass using aqueous solution. The effects of the growth temperature, growth concentration, Al-doped for ZnO epitaxial growth, and AZO microharvesting are determined. Results show the percent transmittance decreases with increasing growth concentration ratio and the peak intensity of the (002) orientation increased with increasing growth temperature. The ZnO doped Al with zigzag structures have good efficiency of microharvesting due to its larger geometrical strain to area ratio.
Authors: Te Hua Fang, Win Jin Chang, Haw Long Lee, Sie Jhan Wu
Abstract: Molecular dynamics (MD) simulation with a tight-binding potential is used to studied the mechanical behaviors of nanoimprinted Cu-Ni alloys before and after annealing. The annealing process consists of three different stages. Initially, there is a gradual heating from the original temperature of 300 K to the specified annealing temperature of 823 K and then it is followed by a period of constant heating at that temperature, after which the specimen temperature is allowed to cool gradually to the original temperature. The results showed that when the punch is advancing, the punching force obtained from the simulation with a tight-binding potential is lower than with the Morse potential. The internal energy of Cu-Ni alloys decreased with increasing the temperature and the component of Cu during the annealing process. In addition, comparing the residual stress in the Cu-Ni alloys with and without annealing treatment, the stress is significantly released after annealing.
Authors: Te Hua Fang, S.H. Kang
Abstract: The characteristics of morphology, friction and nanotribological properties of ZnO thin films were achieved by means of x-ray diffraction, scanning probe microscopy (SPM), and nanoindentation. The ZnO thin films were deposited by a radio frequency magnetron sputtering system. Surface geometry and friction analysis were derived from atomic force microscopy/friction force microscopy (AFM/FFM). The hardness and Young’s modulus of the ZnO thin films were investigated by nanoindentation measurements with a Berkovich indenter. The films exhibited an increase in the hardness with decreasing load i.e. the indentation size effect (ISE) was found. In addition, the nanoscratched mechanical property of the films was discussed.
Authors: Tung Sheng Yang, Te Hua Fang, C.T. Kawn, G.L. Ke, S.Y. Chang
Abstract: Instrumented indentation is widely used to probe the elastic and plastic properties of engineering materials. Finite Element Method (FEM) has been widely used for numerical simulation of indentation tests on bulk and film material in order to analyze its deformation response. This study proposed an improved technique to determine the stress-strain curve of bulk material. FEM in conjunction with an abductive network is used to predict the stress-strain relationship of bilinear elastic-plastic material from the nanoindentation test’s force-displacement curve.
Authors: Yu Fen Chen, Te Hua Fang, Chen Chih Huang, Chien Hung Liu, Wen Hsiang Hsieh
Abstract: This study discuss the distribution of the flows when the forced convection impacted on the spin and the static in table tennis; the research method is using the thermal flow in the experiment which the thermal flow will reflect according to the imaging principle when it passes through the spin sphere; this can be used to simulate the flows of balls in static condition and backspin ball in high-speed and low-speed rotation; the air flow passes through the spin sphere and generates the ball pressure which forms the quality variation of the spheres in table tennis competition; the results showed that it has a lower drag force, low fluid momentum and lower rectilinear speed when the sphere is in static condition , low Reynolds number; on the contrary, it has a higher drag force and increasing rectilinear speed of flows when the Reynolds number is high. When the ball is in backspin condition, the flows are symmetrical presented, and then the flows are gradually distributed, asymmetrical presented and are upward. The higher the Reynolds number is, the smaller the wake region is due to that the forced convection effect increased; the smaller the Reynolds number is, the ball will have more significant spin kinetic energy increasing rate when the spin speeds up.
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