Ching-Yen Ho

Measurement for temperature on a LED lamp

LED demonstrates a number of benefits compared to traditional incandescent lamps and fluorescent lamps. However, the thermal problem that is brought by heat generated within the LED itself is still a bottleneck that limits the stability, reliability and lifetime of high power LED. In order to understand the temperature characteristics of the LED lamp, this paper utilized the thermocouples to measure the temperature on LED lamp. The effects of the ambient temperature on the surface temperature of the LED lamp were presented.

Hyperthermia Temperature of Magnetic Fluid with Superparamagnetic Nanoparticles Subjected to an Alternating Magnetic Field

This paper conducts the thermal analysis of magnetic fluid with superparamagnetic nanoparticles subjected to an alternating magnetic field. Magnetic fluid hyperthermia (MFH) provides a potential method for cancer treatment, which has fewer side effects than chemotherapy and radiotherapy. Superparamagnetic nanoparticles dispersed in water are suitable for safe application of MFH. A well-defined hyperthermia should only kill the cancer cells without injuring neighbouring normal tissue. A key factor for hyperthermia is to correctly control the alternating magnetic field-induced temperature of the magnetic fluid in the tumour. Therefore, this study develops a thermal transport model combined with a linear response theory of magnetic nanoparticle (MNP) heat dissipation to analyze the effects of parameters on temperatures in the magnetic fluid with superparamagnetic nanoparticles subjected to an alternating magnetic field. The results predicted by this model are compared with the available experimental data and show that the rise rates of temperature with time and temperatures along the radial direction are enhanced by the increase of MNP concentrations in magnetic fluid, the amplitude of magnetic field strength, frequency, and magnetization.

Nanoscale Removal of Picosecond Laser Ablation for Polymer.

This paper analytically investigates the picosecond laser ablation of polymer. Laser-pulsed ablation is a well-established tool for polymer. However the ablation mechanism of laser processing for polymer has not been thoroughly understood yet. This study utilized a thermal transport model to analyze the relationship between the ablation rate and laser fluences. This model considered the energy balance at the decomposition interface as the ablation mechanisms and is applied to predict the laser-ablated depth of Acrylonitrile Butadiene Styrene/PolyVinyl Chloride (ABS/PVC). The calculated variation of the ablation rate with the logarithm of the laser fluence agrees with the measured data. The effects of material properties and processing parameters on the ablation depth per pulse are discussed for picosecond laser processing of ABS/PVC.

Method of Teaching Diagnosis and Improvement Integrating Quality Control Concept

This paper proposes that the method of diagnosing and improving production and quality in the business community is applied to teaching diagnosis and improvement. Let teaching diagnosis and improvement be more concrete and practical rather than formalized in the slogans and words, without knowing how to implement it. And the method proposed in this paper is compared with the eight-step strategy such as knowing how to do, investigating (checking up) the real reasons, analyzing problems, confirming the problems needed to be improved, assuring advance in improvement, understanding the status, modulating the actions, and checking up the method. Results show that there are more concrete practice mode of operation for the method of teaching diagnosis and improvement proposed in this paper. Teaching improvement with the rolling continuous improvement concept makes the teaching quality refinement more sophisticated, perfect and then perfect.

A novel spatial-distribution-function of electron beam-induced vapor plume for analyzing EBPVD thickness

This paper investigates the thickness distribution of substrate coating of electron-beam physical vapor deposition (EBPVD) using a novel spatial-distribution-function, which is different from the empirical modified law. The Knudsen cosine law and empirical modified law were usually used for predicting coating thickness in EBPVD. However, these two laws obtained from experiments and geometric concepts cannot provide the elucidation for physical point of view and all-inclusive spatial-distribution-functions. Therefore, instead of the spatial-distribution-functions based on the Knudsen cosine law for low evaporation rates and empirical modified law for the higher evaporation rates, the spatial distribution function based on the mass diffusion theory is proposed to analyze the coating thickness of EB-induced physical vapor deposition. The coating thicknesses predicted by these spatial-distribution-functions are compared with the data measured by the published papers. The results reveal that the coating thicknesses predicted by the spatial distribution function of the diffusion theory are more consistent with the measured data than these obtained from the spatial distribution function of the empirical modified law. The spatial distribution function proposed by this study is validated by correctly predicting the measured coating thickness for EBPVD of titanium and aluminum.

Analysis on ultrashort-pulse laser ablation for nanoscale film of ceramics

This paper uses the dual-phase-lag model to study the ablation characteristics of femtosecond laser processing for nanometer-sized ceramic films. In ultrafast process and ultrasmall size where the two lags occur, a dual-phase-lag can be applied to analyse the ablation characteristics of femtosecond laser processing for materials. In this work, the ablation rates of nanometer-sized lead zirconate titanate (PZT) ceramics are investigated using a dual-phase-lag and the model is solved by Laplace transform method. The results obtained from this work are validated by the available experimental data. The effects of material thermal properties on the ablation characteristics of femtosecond laser processing for ceramics are also discussed.

Effect analysis of material properties of picosecond laser ablation for ABS/PVC

This paper analytically investigates the picosecond laser ablation of ABS/PVC. Laser-pulsed ablation is a wellestablished tool for polymer. However the ablation mechanism of laser processing for polymer has not been thoroughly understood yet. This study utilized a thermal transport model to analyze the relationship between the ablation rate and laser fluences. This model considered the energy balance at the decomposition interface and Arrhenius law as the ablation mechanisms. The calculated variation of the ablation rate with the logarithm of the laser fluence agrees with the measured data. It is also validated in this work that the variation of the ablation rate with the logarithm of the laser fluence obeys Beer’s law for low laser fluences. The effects of material properties and processing parameters on the ablation depth per pulse are also discussed for picosecond laser processing of ABS/PVC.

Thermal characteristics of region surrounding laser welding keyhole

This paper investigates the thermal characteristics of region surrounding laser welding keyhole. The thermal characteristics of region surrounding laser keyhole play an important role on the mechanical properties after welding. The welding keyhole produced by laser welding is assumed to be a paraboloid of revolution. The laser beam with Gaussian distribution of intensity irradiates on the keyhole. Considering the phase change at solid-liquid interface, this study utilized the finite difference method to numerically calculate the thermal fields in the solid and liquid region surrounding laser welding keyhole.

Comparison of ultrashort-pulse-laser ablation characteristics for different ceramics

This paper analytically investigates the ultrashort-pulse-laser ablation characteristics for different ceramics. Ceramics processing is difficult due to its hard and brittle properties. Noncontact ultrashot-pulse-laser is widely recognized to be a applicable tool. The optical property, thermal conductivity, and thermal expansion coefficient of AhO3 Ceramics are obviously different from these of AlN ceramics and are significantly relevant to the ablation characteristics of these ceramics. Therefore, the ablation for Al2O3 and AlN ceramics is quantitatively analyzed in this study. The effects of the ceramics properties on the ablation characteristics are discussed by comparing the ablation of Al2O3 with AlN.

Nonlinear Characteristics of Plasma Induced by an Electron Beam Irradiating the Target Material

This paper studies the nonlinear characteristics of plasma induced by an electron beam irradiating the target material. Poissons equation, the equations of continuity, and momentum equation are employed to investigate the nonlinearity of the electron beam-induced plasma. The steady-state three equations are combined into a nonlinear second-order ordinary differential equation. The physical phenomena resulted from the nonlinear second-order ordinary differential equation are analyzed and presented in this paper. The effects of parameters on the nonlinear characteristics are also discussed.