Browsing by Author "TSAI, CM"

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ANALYSIS OF CUTTING FORCES IN BALL-END MILLING
(1995-01-01)
CHIANG, ST
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TSAI, CM
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LEE, AC
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機械工程學系
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Department of Mechanical Engineering
A cutting force model for ball end milling is developed, the model being based mainly on the assumption that the cutting force is equal to the product of the cutting area and the specific cutting force. The formulation of the cutting area is derived from the geometry of the mill and the workpiece, whilst the specific cutting force is obtained by third-order curve-fitting of data measured in experiments. The model established in this paper predicts the cutting forces in ball-end milling much more accurately than to previous models.
DIRECT OBSERVATION OF SI DELTA-DOPED GAAS BY TRANSMISSION ELECTRON-MICROSCOPY
(1992-05-25)
LIU, DG
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FAN, JC
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LEE, CP
;
TSAI, CM
;
CHANG, KH
Direct observation of the Si delta-doped layer in GaAs has been achieved by high resolution transmission electron microscopy. Samples with different Si doses, from half a monolayer to two monolayers, were studied. The observed spreading of the delta-doped layer showed that Si atoms are largely confined in five monolayers at most (in the highest dose case), indicating excellent confinements of dopants in GaAs. From the images, the Si atoms were uniformly distributed in the doped layer, no cluster formation was observed. For delta-doped GaAs grown at low temperature (480-degrees-C), stacking faults originated from the doped layers were observed. These faults were thought to be caused by the large unrelaxed strain in the low-temperature grown GaAs.
DUAL-WAVELENGTH BRAGG REFLECTORS USING GAAS/ALAS MULTILAYERS
(1993-10-28)
LEE, CP
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TSAI, CM
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TSANG, JS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Dual-wavelength Bragg reflectors have been demonstrated using GaAs/AlAs multilayer heterostructures. Desired reflection bands can be obtained by adding proper phase shifters in a GaAs/AlAs periodic multilayer structure. The structure is based on the digital representation of the addition of two periodic functions.
ENHANCEMENT OF ELECTRON-WAVE REFLECTION BY SUPERLATTICES WITH MULTIPLE STACKS OF MULTIQUANTUM BARRIERS
(1994-02-28)
YEN, ST
;
TSAI, CM
;
LEE, CP
;
LIU, DC
;
電子工程學系及電子研究所
We report a superlattice (SL) with multiple stacks of multiquantum barriers (MQB), which can reflect electrons more effectively than with a single stack of MQB. The reflectivities are calculated and compared with one another for a variety of potential barrier structures. The multistack SL has a wider energy spectrum within which electrons are reflected. Four types of n-GaAs/i-barrier/n-GaAs diodes were fabricated to confirm the calculated results. The current-voltage characteristics measured at 77 K for these diodes show that the turn-on voltage increases with the number of stacks of MQBs in the SL. This is in agreement with our calculated results.
ENHANCEMENT OF ELECTRON-WAVE REFLECTION BY SUPERLATTICES WITH MULTIPLE STACKS OF MULTIQUANTUM BARRIERS
(1994-02-28)
YEN, ST
;
TSAI, CM
;
LEE, CP
;
LIU, DC
;
電子工程學系及電子研究所
We report a superlattice (SL) with multiple stacks of multiquantum barriers (MQB), which can reflect electrons more effectively than with a single stack of MQB. The reflectivities are calculated and compared with one another for a variety of potential barrier structures. The multistack SL has a wider energy spectrum within which electrons are reflected. Four types of n-GaAs/i-barrier/n-GaAs diodes were fabricated to confirm the calculated results. The current-voltage characteristics measured at 77 K for these diodes show that the turn-on voltage increases with the number of stacks of MQBs in the SL. This is in agreement with our calculated results.
FUNDAMENTAL MODE-OPERATION OF HIGH-POWER INGAAS/GAAS/ALGAAS LASER ARRAYS
(1993-05-01)
TSANG, JS
;
LIOU, DC
;
TSAI, KL
;
CHEN, HR
;
TSAI, CM
A new ridge waveguide laser array with stable fundamental mode operation has been fabricated. By introducing absorption regions in all the laser stripes except for the central one, the electric field distribution of the laser arrays and the modal gains of the array supermodes are changed, resulting in fundamental mode operation. The threshold current of an array with five elements is typically 40 mA and the maximum output power is higher than 150 mW. The single-lobed far-field pattern centered at 0-degrees with full width at half maximum of 2-degrees is obtained at 1.5 times of the threshold current (I(th)).
INFLUENCE OF X-VALLEY SUPERLATTICE ON ELECTRON BLOCKING BY MULTIQUANTUM BARRIERS
(1994-11-21)
YEN, ST
;
LEE, CP
;
TSAI, CM
;
CHEN, HR
;
電子工程學系及電子研究所
INVESTIGATION OF INDIUM DOPING IN INGAAS GAAS ALGAAS GRADED-INDEX SEPARATED CONFINEMENT HETEROSTRUCTURE LASERS
(1993-10-15)
TSANG, JS
;
LEE, CP
;
LIU, DC
;
CHEN, HR
;
TSAI, KL
The effect of indium doping in the graded-index regions of the InGaAs/GaAs/AlGaAs graded-index separated confinement heterostructure quantum well laser has been studied. It was found that the threshold current density can be greatly reduced by a proper amount of In doping in the graded AlGaAs region. This result is attributed to an improvement in material quality due to a reduction in group III vacancies. The effect of thermal treatment on laser performance has also been studied. Although high temperature annealing can significantly improve non-In-doped lasers, it has little effect on In-doped lasers.
ONLINE METHOD FOR MEASUREMENT OF THE DISPERSION COEFFICIENT OF RADIONUCLIDE MIGRATION USING A COLUMN METHOD
(1992-12-01)
LIU, WC
;
LO, JG
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TSAI, CM
;
環境工程研究所
;
Institute of Environmental Engineering
An On-line method to obtain breakthrough curves from a conservative tracer generated in crushed rock columns has been introduced. The breakthrough curve can be used to evaluate some important hydrologic Parameters for studying radionuclide migration in groundwater system. These parameters include the dispersion coefficient, average flow yelocity, effective porosity, and retardation factor of the columns tested. A conservative radiotracer, I-131, was used to generate the breakthrough curves, and linear regression analysis was applied to obtain the optimum value of dispersion coefficient. The effects of the injected volume of radioactive tracer, average flow velocity, and effective diameter of packed material on the dispersion coefficient as well as the stability of the packed material, and their in-situ application are discussed.
ONLINE METHOD FOR MEASUREMENT OF THE DISPERSION COEFFICIENT OF RADIONUCLIDE MIGRATION USING A COLUMN METHOD
(1992-12-01)
LIU, WC
;
LO, JG
;
TSAI, CM
;
環境工程研究所
;
Institute of Environmental Engineering
An On-line method to obtain breakthrough curves from a conservative tracer generated in crushed rock columns has been introduced. The breakthrough curve can be used to evaluate some important hydrologic Parameters for studying radionuclide migration in groundwater system. These parameters include the dispersion coefficient, average flow yelocity, effective porosity, and retardation factor of the columns tested. A conservative radiotracer, I-131, was used to generate the breakthrough curves, and linear regression analysis was applied to obtain the optimum value of dispersion coefficient. The effects of the injected volume of radioactive tracer, average flow velocity, and effective diameter of packed material on the dispersion coefficient as well as the stability of the packed material, and their in-situ application are discussed.
ROLE OF CLADDING LAYER THICKNESSES ON STRAINED-LAYER INGAAS/GAAS SINGLE AND MULTIPLE-QUANTUM-WELL LASERS
(1993-06-15)
LIU, DC
;
LEE, CP
;
TSAI, CM
;
LEI, TF
;
TSANG, JS
The influences of cladding layer thicknesses on the performance of strained-layer InGaAs/GaAs graded-index separated confinement heterostructure quantum well lasers have been studied. The waveguiding property of the laser structure was analyzed using the transfer matrix method. In this work, experimental results and the calculated results showed that threshold current densities and external quantum efficiencies both were crucially dependent on the thicknesses of cladding layer for both single and multiple quantum well lasers. The minimum cladding layer thicknesses needed to maintain low threshold current densities and low internal total loss for both single and multiple quantum well devices were determined experimentally and theoretically.
THE STUDY ON IMPROVING MASONRY CEMENT FOR THE SOLIDIFICATION OF BORATE WASTES
(1989)
SHIAO, SJ
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TSAI, CM
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交大名義發表
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應用化學系
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National Chiao Tung University