Browsing by Issue Date, starting with "1999-05-15"

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子宮是詩誕生的自然也是詩
(1999-05-15)
管管
Spin-dependent tunneling in double-barrier semiconductor heterostructures
(1999-05-15)
Voskoboynikov, A
;
Liu, SS
;
Lee, CP
;
交大名義發表
;
National Chiao Tung University
Spin-dependent tunneling in symmetric and asymmetric double-barrier semiconductor heterostructures is studied. The effective one-band Hamiltonian approximation and spin-dependent boundary conditions approach an used for a theoretical investigation of the influence of electron spin on the tunneling probability. It is shown that spin-orbit splitting in the dispersion relation for electrons in A(III)B(V) semiconductors can provide the dependence of the tunneling transmission probability on the electron-spin polarization without additional magnetic field. The dependence can be controlled by an external electric field, and may be significant for realistic models of double-barrier semiconductor heterostructures. [S0163-1829(99)02320-6].
The spatially-distributed recording of the composite filter using the pixelated liquid crystal display
(1999-05-15)
Tsai, J
;
Lin, SH
;
Hsieh, TC
;
Hsu, K
;
電子物理學系
A new recording method using a liquid crystal display (LCD) as an input device to synthesize a composite filter is presented. The filter in the optical correlator makes use of the multiple diffraction orders from the pixelated structure of the LCD panel. During the recording stage, each training pattern is sequentially recorded as a sub-filter at different diffracted order by holographic technology. After that, an input pattern could be simultaneously processed with all sub-filters in parallel such that the composite filter can be achieved. This recording method with spatial distribution could avoid the low efficiency of the conventional multi-exposure. The simulations and experimental results show that this system can perform invariant correlation as a composite filter. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
七十當老爸
(1999-05-15)
蘇嫻雅
Elimination of dynamic instabilities in the plus c-face incident photorefractive BaTiO3 mutually pumped phase conjugator
(1999-05-15)
Chang, CC
;
Chen, TC
;
Tang, LC
;
Yau, HF
;
光電工程學系
Experimental observations of the dynamic instabilities in the +c-face incident mutually pumped phase conjugator (MPPC) of a BaTiO3 crystal are reported for the first time. Experiments show that it is possible to stabilize the phase-conjugate output by choosing a proper geometry formed from the crystal and two incident beams. By choosing the proper geometry the essential configuration of the MPPC attained is a "kite" rather than a "fish head". Data also indicate that the phase-conjugate output can reach a very steady state with a high value (similar to 32%) and is insensitive to angular and positional variations.
給小孩起個好名字看著順眼 ,叫著舒服
(1999-05-22)
管管
Robust SBR method for adverse Mandarin speech recognition
(1999-05-27)
Hong, WT
;
Chen, SH
;
電信工程研究所
;
Institute of Communications Engineering
An RNN-based robust signal bias removal (RRSBR) method is proposed for improving both the recognition performance and the computational efficiency of the SBR method fbr adverse Mandarin speech recognition. It differs from the SBR method in using three broad-class sub-codebooks to encode the feature vector of each frame and combining the three encoding residuals to form the frame-level signal bias estimate. A novel approach involving softly combining the board-class encoding residuals using dynamic weighting functions generated by an RNN is applied. Experimental results show that the RRSBR method significantly outperforms the SBR method.
Foundation of direct perturbation method for dark solitons
(1999-05-28)
Huang, NN
;
Chi, S
;
Chen, XJ
;
光電工程學系
;
Department of Photonics
The foundation of the direct perturbation theory for solitons is a complete set of the squared Jest functions. With a suitable definition of the adjoint functions and inner products which yields orthogonal relations, the expansion of the the unity is obtained and the completeness is shown by a generalized Marchenko equation. The direct perturbation method for dark solitons is generalized to the multi-soliton case.
Two design patterns for data-parallel computation based on master-slave model
(1999-05-28)
Huang, KC
;
Wang, FJ
;
Tsai, JH
;
資訊工程學系
;
Department of Computer Science
This paper presents two design patterns useful for parallel computations of master-slave model. These patterns are concerned with task management and parallel and distributed data structures. They can be used to help addressing the issues of data partition and mapping, dynamic task allocation and management in parallel programming with the benefit of less programming efforts and better program structures. The patterns are described in object-oriented notation, accompanied with illustrative examples in C++. We also provide our experience in applying these patterns to two scientific simulation programs simulating Ising model and plasma physics respectively. Since master-slave model is a widely used parallel programming paradigm, the design patterns presented in this paper have large potential application in parallel computations. (C) 1999 Elsevier Science B.V. All rights reserved.
An efficient algorithm for computing quantiles of the noncentral chi-squared distribution (vol 29, pg 253, 1999)
(1999-05-28)
Ding, CG
;
管理科學系
;
Department of Management Science
大家都愛騙子
(1999-05-29)
管管
The application of laser metrology and resonant optical cavity techniques to the measurement of G
(1999-06-01)
Ni, WT
;
Liu, DK
;
Liu, TT
;
Mei, HH
;
Pan, SS
Our goal is to measure the gravitational constant G to within 1-10 ppm using a high-finesse Fabry-Perot optical cavity. The two high-reflectivity mirrors of the Fabry-Perot cavity will be suspended separately by two nearly identical simple pendulums of length about 1 m. For the source of attraction, we have built a rotating mass source with 12 lead bricks (each brick is of mass 11.5 kg) on each of two opposite sides of a rotating table. The period of rotation can be adjusted. We normally use a rotation period of 200 s. For this rotating mass, the relative equilibrium displacement of the two mirrors is over 10 nm and we are working for a preliminary measurement of this distance to one part in 10(4). Auxiliary quantities such as the positions of the test mass and the positions of Fabry-Perot cavity mirrors can be monitored using real-time laser metrology. The stability and real-time monitoring of the pendulums, building stability, and the compensation or averaging of mass inhomogeneity need special considerations.
Synthesis and characterization of liquid crystalline multiblock copolyesters of oxybenzoate and ethylene terephthalate
(1999-06-01)
Ho, JC
;
Lin, YS
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Multiblock copoly(oxybenzoate-p-ethylene terephthalate) (POB-PET) was synthesized by a direct reaction of poly(hydroxybenzoic acid) (PHBA), acetoxybenzoic acid and poly(ethylene terephthalate). The synthesized multiblock POB-PET becomes more blocky and less soluble in the mixed solvent of trifluoroacetic acid and chloroform when the degree of polymerization of PHBA used in the synthesis is higher as evidenced in the solid-state and liquid-state nuclear magnetic resonance study. The thermal curves displayed by the synthesized multiblock 20/80 and 40/60 POB-PET contained distinctive contributions from both PET blocks and POB blocks in the copolymers when the degree of polymerization of PHBA used in the synthesis is seven. Only 20 mol% of POB is needed to form liquid crystalline phase in these multiblock POB-PET as opposed to a minimum of 40 mol% of POB is required to form liquid crystalline phases for random POB-PET. (C) 1999 Elsevier Science Ltd. All rights reserved.
Obstacle avoidance for autonomous land vehicle navigation in indoor environments by quadratic classifier
(1999-06-01)
Ku, CH
;
Tsai, WH
;
資訊工程學系
;
Department of Computer Science
A vision-based approach to obstacle avoidance for autonomous land vehicle (ALV) navigation in indoor environments is proposed. The approach is based on the use of a pattern recognition scheme, the quadratic classifier, to find collision-free paths in unknown indoor corridor environments. Obstacles treated in this study include the walls of the corridor and the objects that appear in the way of ALV navigation in the corridor. Detected obstacles as well as the two sides of the ALV body are considered as patterns, A systematic method for separating these patterns into two classes is proposed. The two pattern classes are used as the input data to design a quadratic classifier, Finally, the two-dimensional decision boundary of the classifier, which goes through the middle point between the two front vehicle a heels, is taken as a local collision-free path, This approach is implemented on a real ALV and successful navigations confirm the feasibility of the approach.
A 2-V, 1.8-GHz BJT phase-locked loop
(1999-06-01)
Chen, WZ
;
Wu, JT
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper describes the design of a bipolar junction transistor phase-locked loop (PLL) for Sigma Delta fractional-N frequency-synthesis applications. Implemented in a 0.8-mu m BICMOS technology, the PLL can operate up to 1.8 GHz while consuming 225 mW of power from a single -2-V supply. The entire LC-tuned negative-resistance variable-frequency oscillator is integrated on the same chip. A differential low-voltage current-mode logic circuit configuration is used in most of the PLL's functional blocks to minimize phase jitter and achieve low-voltage operation. The multimodulus frequency divider is designed to support multibit digital modulation. The new phase and frequency detector and loop filter contain only npn transistors and resistors and thus achieve excellent resolution in phase comparison. When phase locked to a 53.4-MHz reference clock, the measured phase noise of the 1.6-GHz output is -91 dBc/Hz at 10-kHz offset, The frequency switching time from 1.677 to 1.797 GHz is 150 mu s. Die size is 4300 x 4000 mu m(2), including the passive loop filter.
Application of selective liquid-phase deposition to fabricate contact holes without plasma damage
(1999-06-01)
Yeh, CF
;
Liu, CH
;
Su, JL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work develops an alternative method, selective liquid-phase deposition (S-LPD), to fabricate contact holes instead of reactive ion etching. In preliminary experiments, deep n(+)/p junction diodes with contact holes prepared by S-LPD exhibit much less reverse current, unity ideality factor, larger forward current, lower contact resistance, and higher thermal stability than those prepared by reactive ion etching. Further superiority of plasma damage-free near-surface regions is also investigated using Schottky and ultrashallow junction diodes. Experimental results indicate that S-LPD can be applied to the submicron contact-hole process. The data after reverse bias temperature stress reveals the satisfactory reliability of S-LPD contact holes. This work demonstrates that the S-LPD technology is a highly promising means of replacing reactive ion etching processes to form submicron contact holes as reliably as those by wet-etching. (C) 1999 The Electrochemical Society. S0013-4651(98)08-119-1. All rights reserved.
One-loop Vilkovisky-DeWitt effective potential for scale-invariant gravity
(1999-06-01)
Lin, SY
;
Ng, KW
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
For a pure gravity theory without matter, the scale symmetric phase represents an equivalent class of gravity theories, to which the Einstein gravity plus a cosmological constant belongs under a special gauge choice. The one-loop quantum correction of this scale-invariant theory is calculated by using Vilkovisky-DeWitt's method. It is shown that the resulting effective potential is gauge-independent as expected. Some discussions of the Vilkovisky-DeWitt method through this calculation are given.
Effects of BF2+ implantation on the oxidation resistance of copper films
(1999-06-01)
Wu, ZC
;
Liu, YL
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the effects of BF2+ implantation on the oxidation resistance of copper films. The BF2+ ions were implanted into Cu films through a 1000 Angstrom thick screen SiO2 layer. We found that the oxidation resistance of Cu films can be significantly improved by BF2+ implantation at appropriate conditions. In particular, BF2+ implantation at 35 to 40 keV to a dose of 1 - 8 x 10(14) cm(-2) made the Cu films capable of resisting oxidation at temperatures up to 250 degrees C. At these BF2+ implantation energies, boron atoms of peak concentration were projected near the Cu surface; thus the diffusion paths of oxidizing species were efficiently blocked. Implantation at too high energy would result in greater depth of projection, thus a lower concentration of boron at the Cu surface; moreover, it generally leads to increased implantation defects that might serve as diffusion paths for the oxidation species. On the other hand, too high dosage implantation would also have an adverse effect on the capability of oxidation resistance for Cu films owing to the higher density of implantation damage as well as the formation of reactive fluorine compound (CuF2) near the Cu surface. (C) 1999 Elsevier Science S.A. All rights reserved.
CSO distortions due to the combined effects of self- and external-phase modulations in long-distance 1550-nm AM-CATV systems
(1999-06-01)
Wu, MC
;
Wang, CH
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
We found that the combined effects of self- and external-phase modulations must be considered in order to precisely predict the composite second-order distortions in a long-distance 1550-nm externally modulated AM-cable TV (CATV) system, especially when the applied phase modulation index and modulating tone frequency to the integrated phase modulator are high, This result has important implications to the optimum design of 1550-nm transmitter for long-distance Am- and QAM-CATV systems.
Electromigration in sputtered copper films on polyimide
(1999-06-01)
Wang, HW
;
Chiou, BS
;
Jiang, JS
;
電子物理學系
;
電子工程學系及電子研究所
Electromigration damage (EMD) is one of the major causes for the failures of interconnects. In this study, the electromigration of Cu on polyimide is investigated. An empirical formula is used to evaluate the EMD of Cu film. The activation energy (Q) obtained is significantly less than those of lattice and grain boundary diffusion. This suggests that the electromigration in copper proceeds via an interfacial diffusion path. The geometry of the metallization also affects the activation energy. Any abrupt change in the interconnect direction and metal width causes current crowding and should be avoided. The current exponents (n), calculated from EMD data, are 3.58 and 3.35 for straight and zig-zag Cu films, respectively.