Browsing by Issue Date, starting with "2000-08-15"

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Obliquely tilted discotic phase compensation films
(2000-08-15)
Wu, LH
;
Luo, SJ
;
Hsu, CS
;
Wu, ST
;
應用化學系
A three-step method was developed to fabricate the obliquely tilted discotic negative birefringence phase compensation films. Model fitting reveals that the tilt angle of the discotic directors is about 46 degrees from surface normal. The total phase retardation value of the film can be controlled by the discotic layer thickness. These asymmetric phase retardation films are useful for widening the viewing angle of a liquid crystal display device.
The parametric solutions of eigenstructure assignment for controllable and uncontrollable singular systems
(2000-08-15)
Wang, AP
;
Lin, SF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The previous results about the parametric solutions of eigenstructure assignment for singular systems applied by pure proportional or proportional-plus-derivative state feedback can only apply to controllable systems. It is because the parametric solutions of the right generalized eigenvectors corresponding to the infinite and uncontrollable finite eigenvalues have still not been found. In this paper, the parametric solutions of the right generalized eigenvectors for finite controllable (or uncontrollable) eigenvalues and infinite controllable (or uncontrollable) eigenvalues, when the system is applied by pure proportional or proportional-plus-derivative state feedback, are given. Hence, the parametric solution of eigenstructure assignment can be used to design the state feedback of both the controllable and uncontrollable systems. The condition for detecting the regularity of the resulting system is also given. (C) 2000 Academic Press.
Progress in the developments of (Ba,Sr)TiO3 (BST) thin films for Gigabit era DRAMs
(2000-08-15)
Ezhilvalavan, S
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper reviews the recent developments of (Ba,Sr)TiO3 (BST) thin films for future Gbit era dynamic random access memory (DRAM) applications. The trends of DRAM capacitors in the last decade are briefly described first. Then the technological aspects of BST films such as deposition techniques, post-annealing, physical, electrical and dielectric characteristics of the films, effects of electrode materials, dielectric relaxation and defect analysis and the reliability phenomena associated with the films are briefly reviewed with specific examples from recent literature. The basic mechanisms that control the bulk electrical conduction and the origin of leakage currents in BST films are also discussed. Finally, possible developments of gigabit era DRAM technology are summarized. (C) 2000 Elsevier Science S.A. All rights reserved.
Ester-amide exchange in blends of liquid-crystalline copolyester and polyamide 6
(2000-08-15)
Ho, JC
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The kinetics of the ester-amide exchange in solution blends of the random liquid-crystalline polyester copoly(oxybenzoate-terephthalate) (P64) and polyamide 6 (PA6) were studied with carbon nuclear magnetic resonance. With second-order reversible reactions assumed, the activation energy of the ester-amide interchange in 30/70, 50/50, and 70/30 P64/PA6 blends were all about 24.0 kcal/mol. The pre-exponential factors for the ester-amide exchange in 30/70, 50/50, and 70/30 P64/PA6 blends were 2.01 x 10(11), 2.59 x 10(10), and 2.74 x 10(12) min(-1), respectively. (C) 2000 John Wiley & Sons, Inc.
Study on Ge/Si ratio, silicidation, and strain relaxation of high temperature sputtered Co/Si1-xGex structures
(2000-08-15)
Huang, HJ
;
Chen, KM
;
Chang, CY
;
Huang, TY
;
Chen, LP
As the transistors continue to scale down, the characteristics of high-temperature-sputtered Co/Si1-xGex junction have received lots of attention because of its potential applications to heterojunction bipolar transistors. In this study, we have fabricated Co/Si1-xGex junction using room-temperature and high-temperature (i.e., at 450 degrees C) sputtered Co on top of strained Si0.86Ge0.14 and Si0.91Ge0.09 layers prepared by ultrahigh vacuum chemical molecular epitaxy. The relative composition of Ge in Ge-rich Si1-zGez precipitate and the solid solution of ternary phase silicide of Co-Si-Ge system were compared between room-temperature and high-temperature sputtered samples. We found that the high-temperature-sputtered samples are more effective in inhibiting lattice relaxation, which would be beneficial for manufacturing metal silicide/Si1-xGex structure devices. Mechanisms were proposed to explain the large difference between the room-temperature and high-temperature sputtered samples. It is believed that the mixed Co-Si-Ge solution on high-temperature-sputtered samples is responsible for the different silicidation behaviors. (C) 2000 American Institute of Physics. [S0021-8979(00)02616-5].
Multiaction maintenance subject to action-dependent risk and stochastic failure
(2000-08-16)
Su, CT
;
Wu, SC
;
Chang, CC
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Although Markov maintenance problems have received extensive attention, relatively few studies have addressed multiple nonreplacement maintenance actions for a multistate system with action-dependent risk and stochastic failure. In this study, we closely examine such multiple maintenance actions by viewing a coherent multicomponent system as a multistate system and assuming that each maintenance action regarding state improvement has a probabilistic risk which is ineffective. The above problem is also modeled as a Markov maintenance problem, demonstrating that the optimal maintenance policy has easily computed and implemented control limit rule. More specially, results in this study confirm the practical nature of the proposed model with respect to its ability than most conventional Markov maintenance models for some particular systems. (C) 2000 Elsevier Science B.V. All rights reserved.
The exact Green function of a relativistic Coulomb system via the transformation method
(2000-08-18)
Chuu, DS
;
Luan, PG
;
Lin, DH
;
電子物理學系
;
Department of Electrophysics
The exact Green function of a relativistic Coulomb system is given by the transformation method. The earlier treatments are based on the multiple-valued transformation of Kustaanheimo and Stiefel as well as the perturbation expansions. The method presented in this paper relates the relativistic Coulomb path integral to the simple ones and may apply to a large class of problems.
金門的一個明朝小村裡的那棵梨花　
(2000-08-20)
管管
金門的一個明朝小村裡的那棵梨花　
(2000-08-20)
管管
金門的一個明朝小村裡的那棵梨花　
(2000-08-20)
管管
金門的一個明朝小村裡的那棵梨花　
(2000-08-20)
管管
Face selectivity in the reactions of 2,4-disubstituted adamantanes.
(2000-08-20)
Chung, WS
;
Chu, JH
;
應用化學系
;
Department of Applied Chemistry
The effect of oxygen-to-argon ratio on the electrical and reliability characteristics of sputtered Sr0.8Bi2.5Ta1.2Nb0.9O9+x thin films
(2000-08-22)
Tsai, MS
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigated how the annealing process affects the ferroelectric properties of thin films of Sr0.8Bi2.5Ta1.2Nb0.9O9+x (SBTN) on Ir/SiO2/Si substrates prepared by two-target off-axis rf magnetron sputtering at various O-2/(Ar + O-2) mixing ratios (OMR) with a substrate temperature of 570 degrees C. Experimental results indicated that the annealing could effectively result in a large remanent polarization. The remanent polarization, dielectric constant and leakage current of 598 degrees C post-annealing SBTN thin films increased with an increase in the OMR and reached a maximum value at 40% OMR. In addition, the results obtained from the dielectric constant and the leakage current were interpreted in terms of polarization effect and loss theory. The 400-nm thick 40% OMR SBTN films with 598 degrees C post-annealing exhibited good surface morphology and had a dielectric constant of 752, a loss tangent of 0.035 at 100 kHz, a leakage current density of 6 x 10(-6) A/cm(2) at an electric field of 50 kV/cm with a delay time of 30 s, a remanent polarization (2P(r)) of 40 mu C/cm(2), a coercive field (2E(c)) of 77 kV/cm at an applied voltage of 3 V, and a measured value of Q(sw) of 20 mu C/cm(2). According to studies on the 10-year lifetime of time-dependent dielectric breakdown (TDDB), high OMR samples have a longer lifetime than the other lower OMR samples. The SBTN films demonstrated fatigue free characteristics up to 10(11) switching cycles under a 3-V bipolar 1 MHz square wave. Moreover, the polarization of the films decreases slightly (less 0.5% per decade) with retention time up to 240 min. (C) 2000 Elsevier Science S.A. All rights reserved.
Wafer bonding by low-temperature soldering
(2000-08-25)
Lee, C
;
Huang, WF
;
Shie, JS
;
光電工程學系
;
Department of Photonics
Recently. wafer level packaging received lots of attention in microsystems because it shows the potential to reduce the packaging cost, while the yield of devices after dicing and packaging can be increased. However, there is a limitation of commercialized wafer bonding technology. i.e., the high process temperature, such as 1000 degrees C of silicon fusion bonding, and 450 degrees C of anodic bonding. A novel tow-temperature wafer bonding with process temperature lower than 160 degrees C is proposed, it applies the In-Sn alloy to form the interface of wafer bonding. The experiment results show helium leak test of 6 x 10(-9) Torr 1/s, and a tensile strength as high as 200 kg/cm(2). Reliability test after 1500 temperature cycles between -10 degrees C and 80 degrees C also shows no trace of degradation compared to the initial quality of the samples. This low-temperature soldering process demonstrates its promising potential at the wafer level packaging in industrial production. (C) 2000 Elsevier Science. S.A. All rights reserved.
The dependence of initial states on the excitation of NO molecules by chirped infrared laser pulses
(2000-08-28)
Lin, JT
;
Jiang, TF
;
物理研究所
;
Institute of Physics
We study the effect of initial states on the chirping excitation of NO molecules in order to interpret recent experimental data. The results show that excitation is efficient when the probability density localizes along the polarization direction of the external field. Therefore, the thermal effect on the density distribution must be taken into account for the experimental case of 15 K. Furthermore, as the adiabatic limit is fully satisfied, the interference pattern of excited state populations disappears. This becomes a limiting factor under experimental conditions. We also find that excitation can be enhanced significantly when the pulse intensity is increased to fit the adiabatic criterion.
An intelligent buffer management approach for GFR services in IP/ATM internetworks
(2000-08-30)
Wang, PC
;
Chan, CT
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
In ATM networks, the Guaranteed Frame Rate (GFR) service has been proposed to accommodate non-real-time traffic with packet size not exceeding a maximum length, such as TCP/IP based traffic. The GFR service not only guarantees a minimum throughput at the frame level, but also supports a fair share of available resources. In this article, we propose a buffering strategy called Intelligent Fair Buffer Allocation (IFBA) that provides minimum cell rate (MCR) guarantees and fair sharing to GFR virtual circuits (VCs). From the simulation results, we demonstrate that IFBA fulfills the requirements of GFR service as well as improves the TCP throughput using the FIFO scheduling. (C) 2000 Elsevier Science B.V. All rights reserved.
Spur gear generation by shaper cutters
(2000-08-31)
Tsay, CB
;
Liu, WY
;
Chen, YC
;
機械工程學系
;
Department of Mechanical Engineering
This paper proposes the computerized tooth profile generation of spur gears cut with shaper cutters. A complete geometrical mathematical model of a spur shaper cutter is proposed, including the protuberance, the involute region and semi-topping. The profiles of standard or non-standard spur gears cut with the shaper cutter are obtained based on the theory of gearing. In addition, the effects of the cutter parameters on the generated tooth profile are investigated and illustrated with computer simulation, while the appropriate shaper cutter parameters corresponding to the required gear profile, are also determined using an optimization method. (C) 2000 Elsevier Science S.A. All rights reserved.
The design and development of a hydrostatic extrusion apparatus
(2000-08-31)
Hung, JC
;
Hung, CH
;
機械工程學系
;
Department of Mechanical Engineering
The purpose of this research is to design and construct an experimental hydrostatic extrusion apparatus which has a maximum working pressure of 10 000 kg/cm(2). and to reduce the cost of this extrusion apparatus. The high-pressure extrusion container has been designed with two-layer pyramidal cylinders, and the material used was SKD61 which is cheap and readily available. Different materials and designs for high-pressure seals were tested and analyzed for the best combination performance. Problems in the extrusion processes using this device a ere analyzed and solved, which increased the reliability of the device. The results of extrusion experiments have established that this device is practicable, (C) 2000 Published by Elsevier Science S.A.
Active cancellation of noise in a car cabin using the zero spillover controller
(2000-08-31)
Bai, MSR
;
Chen, HH
;
機械工程學系
;
Department of Mechanical Engineering
In active noise control problems, spillover will occur because of the Bode integral constraint if the performance sensors and measurement sensors are collocated, or if the control speakers and the noise sources are collocate, This paper is focused on the implementation of a multiple-channel zero-spillover ANC controller using a spatially feedforward structure for a car cabin. The plant model is realized by using a frequency-domain procedure. The linear-quadratic-Gaussian algorithm is used in controller design. Experiments are carried out to verify the proposed technique, where random noise and engine noise are chosen as the primary noise. The results indicate that the proposed controller yields a broadband attenuation for the random noise. The proposed method is also effective in attenuating the engine noise if an assumed model of the noise is incorporated into controller design. (C) 2000 Academic Press.
Synthesis of substituted poly (arylene vinylene) films by vapor deposition polymerization
(2000-09-01)
Li, AK
;
Janarthanan, N
;
Hsu, CS
;
應用化學系
;
Department of Applied Chemistry
An efficient method for the synthesis of PPV based polymers, poly (2,5-dimethyl-1,4-phenylene vinylene) (DMe-PPV) and poly (2,5-dimethoxy-1,4-phenylene vinylene) (DOMe-PPV) were developed using 2,5-dimethyl-1,4-bis (chloromethyl) benzene and 2,5-dimethoxy 1,4-bis (chloromethyl) benzene via vapor phase pyrolysis and followed by vapor deposition polymerization. The structure of polymer films were confirmed by FT-IR, solid state NMR and elemental analysis. Thermal gravimetry analysis reveals that the precursor polymer films form a conjugated polymer after thermal conversion at 250 degrees C. The optical and electrical properties of the polymer films were investigated by UV-Vis absorption and photoluminescence spectroscopies. Electroluminescent devices were fabricated using these polymers.