Browsing by Issue Date, starting with "1995-10-02"

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GROWTH AND PROPERTIES OF SUBMILLIMETER SINGLE GRAIN TL2BA2CA2CU3O10+X SUPERCONDUCTING THIN-FILMS
(1995-10-02)
LIN, HC
;
UEN, TM
;
LIU, CK
;
JUANG, JY
;
WU, KH
Distinct crystalline superconducting grains of Tl2Ba2Ca2Cu3O10+x(Tl-2223) with sizes up to 150 mu mx150 mu mX1 mu m were prepared by a single target dc-sputtering process followed by proper postannealing at temperatures around 910 degrees C. A reactive ion etching process was developed to pattern an similar to 10 mu m wide bridge with four contact leads directly on a single grain to study its superconducting transport properties. The etching process was found to have only minimal effect on the superconducting transition temperature T-c, which was typically around 110 K. Grains grown on MgO(100) and LaAlO3(100) substrates, although, displaying somewhat different in-plane orientations, all had critical current densities J(c), well above 10(6) A/cm2 at 77 K. The existence of only one grain boundary, however, can reduce the J(c) by orders of magnitude. (C) 1995 American Institute of Physics.
GROWTH AND PROPERTIES OF SUBMILLIMETER SINGLE GRAIN TL2BA2CA2CU3O10+X SUPERCONDUCTING THIN-FILMS
(1995-10-02)
LIN, HC
;
UEN, TM
;
LIU, CK
;
JUANG, JY
;
WU, KH
Distinct crystalline superconducting grains of Tl2Ba2Ca2Cu3O10+x(Tl-2223) with sizes up to 150 mu mx150 mu mX1 mu m were prepared by a single target dc-sputtering process followed by proper postannealing at temperatures around 910 degrees C. A reactive ion etching process was developed to pattern an similar to 10 mu m wide bridge with four contact leads directly on a single grain to study its superconducting transport properties. The etching process was found to have only minimal effect on the superconducting transition temperature T-c, which was typically around 110 K. Grains grown on MgO(100) and LaAlO3(100) substrates, although, displaying somewhat different in-plane orientations, all had critical current densities J(c), well above 10(6) A/cm2 at 77 K. The existence of only one grain boundary, however, can reduce the J(c) by orders of magnitude. (C) 1995 American Institute of Physics.
OPTICAL-EMISSION SPECTROSCOPY STUDIES OF THE EFFECTS OF NITROGEN ADDITION ON DIAMOND SYNTHESIS IN A CH4-CO2 GAS-MIXTURE
(1995-10-09)
HONG, TM
;
CHEN, SH
;
CHIOU, YS
;
CHEN, CF
;
交大名義發表
The influence of nitrogen on the growth of diamond using the gas mixtures of CHS-CO, by microwave plasma chemical vapor deposition was investigated. A clear improvement in the surface morphology and quality of the diamond films indicates the beneficial effect of adding nitrogen to CH4-CO gas mixtures. Analysis using Auger electron spectroscopy and secondary ion mass spectroscopy shows very low and uniform levels of nitrogen in the diamond films. Atomic nitrogen plays a dominant role in C/H/O/N plasma chemical vapor deposition processes because of the amount of oxygen atoms increased via the titration reaction of nitrogen atoms (a high-rate reaction): N+NO-->N-2+O. This produces a significant influence on diamond synthesis in a CH4-CO2-N-2 gas mixture. (C) 1995 American Institute of Physics.
UNIFIED ARRAY ARCHITECTURE FOR DISCRETE COSINE TRANSFORM, SINE TRANSFORM AND THEIR INVERSES
(1995-10-12)
GUO, JI
;
CHEN, CS
;
JEN, CW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A unified array design for the discrete cosine transform, discrete sine transform and their inverses based on a new general formulation is presented. The presented design provides the flexibility to adaptively select different types of transforms in transform coding according to the characteristics of images for minimising the bit rate as much as possible.
IMPLEMENTATION OF A FUZZY INFERENCE SYSTEM USING A NORMALIZED FUZZY NEURAL-NETWORK
(1995-10-13)
CHAO, CT
;
TENG, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we present a normalized fuzzy neural network (NFNN) to implement fuzzy inference systems. The proposed NFNN architecture makes an effective rule combination technique possible and thus enables us to significantly reduce the number of rules in the NFNN. We also derive a sufficient condition for rule combination and provide an algorithm to perform rule combination. Simulation results show that when combined with a rule elimination method the proposed rule combination method can greatly reduce the number of rules in the NFNN.
ANGULAR-DISTRIBUTION OF ELECTRONS ELASTICALLY BACKSCATTERED FROM NONCRYSTALLINE SOLID-SURFACES
(1995-10-14)
CHEN, YF
;
KWEI, CM
;
SU, P
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In the energy range 100 eV-2 keV, we applied the Monte Carte method to analyse the elastic reflection coefficient and the angular distribution of electrons elastically backscattered from the solid surface of an isotropic and homogeneous medium. Results indicated that elastically backscattered electrons arose substantially from only a few scatterings with a single scattering event contributing to approximately half of these electrons. Thus, neither the multiple scattering model nor the single scattering model is sufficient to describe the angular distribution. To improve these models, we evaluated the contribution from one, two and three scatterings exactly and higher scatterings by the P-1-approximation, an approximate method to solve the Boltzmann transport equation assuming multiple elastic scattering of electrons in the solid. This approach allowed us to derive analytical formulations for the elastic reflection coefficient and the angular distribution of elastically backscattered electrons. Results calculated based on these formulations were in good agreement with those using Monte Carlo simulations and experimental data.
S-METHYL(2R,6S,8S)-2,6-DIMETHOXY-4-METHYL-3,5-DIOXATRICYCLO[5.2.1.0(4,9)]DECANE-8-THIOATE
(1995-10-15)
LIN, CC
;
LIN, CC
;
應用化學系
;
Department of Applied Chemistry
The X-ray analysis of the title compound, C13H20O5S, confirms the trans relationship between the two methoxy groups on atoms C(2) and C(6) of the heterocyclic cage. The torsion angles C(15)-S-C(14)-O(8) and C(9)-C(8)-C(14)-O(8) have values of 0.0 (2) and -15.9 (3)degrees, respectively.
傚蟈蟈而之聲發管管之鳴
(1995-10-22)
李維菁
ANOMALOUS BIAS-STRESS-INDUCED UNSTABLE PHENOMENA OF HYDROGENATED AMORPHOUS-SILICON THIN-FILM TRANSISTORS
(1995-10-23)
TAI, YH
;
TSAI, JW
;
CHENG, HC
;
SU, FC
;
電子工程學系及電子研究所
Thin-film transistors (TFTs) with different silicon nitride (SiNx) gate compositions and various hydrogen concentrations in their amorphous silicon films (a-Si:H) have been stressed with positive and negative biases to realize the instability mechanisms. For both stress polarities, it is found that the threshold voltage shifts significantly increase due to the trap sites in the SiNx gate. As the effects of the trapped charges in the SiNx films are reduced, the anomalous threshold voltage shifts under negative stress voltage are observed. The creation of the states near the conduction band in the a-Si:H films can be enhanced according to the defect pool concept and stimulated by the hydrogen contents in the a-Si:H films, which can be confirmed by the subthreshold swing change. Therefore, the negative threshold voltage shifts caused by the hole trapping in the SiN, gate are positively compensated by the created states, reflecting the turnaround behaviors for the threshold voltage shifts. As for the positive stress, the state creation in the a-Si:H films can be suppressed via the defect pool mechanism and thus the threshold voltage shifts are dominantly affected by the electron trapping in the SiNx gates. (C) 1995 American Institute of Physics.
ANOMALOUS BIAS-STRESS-INDUCED UNSTABLE PHENOMENA OF HYDROGENATED AMORPHOUS-SILICON THIN-FILM TRANSISTORS
(1995-10-23)
TAI, YH
;
TSAI, JW
;
CHENG, HC
;
SU, FC
;
奈米中心
Thin-film transistors (TFTs) with different silicon nitride (SiNx) gate compositions and various hydrogen concentrations in their amorphous silicon films (a-Si:H) have been stressed with positive and negative biases to realize the instability mechanisms. For both stress polarities, it is found that the threshold voltage shifts significantly increase due to the trap sites in the SiNx gate. As the effects of the trapped charges in the SiNx films are reduced, the anomalous threshold voltage shifts under negative stress voltage are observed. The creation of the states near the conduction band in the a-Si:H films can be enhanced according to the defect pool concept and stimulated by the hydrogen contents in the a-Si:H films, which can be confirmed by the subthreshold swing change. Therefore, the negative threshold voltage shifts caused by the hole trapping in the SiN, gate are positively compensated by the created states, reflecting the turnaround behaviors for the threshold voltage shifts. As for the positive stress, the state creation in the a-Si:H films can be suppressed via the defect pool mechanism and thus the threshold voltage shifts are dominantly affected by the electron trapping in the SiNx gates. (C) 1995 American Institute of Physics.
HIGH BREAKDOWN VOLTAGE SCHOTTKY-BARRIER DIODE USING P(+)-POLYCRYSTALLINE SILICON DIFFUSED GUARD RING
(1995-10-26)
LIOU, BW
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new Schottky diode structure which uses the p(+)-polycrystalline silicon (polysilicon) diffused guard ring is proposed. The diode gives nearly ideal J-V characteristics with a high reverse breakdown voltage (148V) and a low reverse leakage current density (8.4 mu A/cm(2)).
STUDY OF SCHOTTKY BARRIERS ON N-TYPE GAN GROWN BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION
(1995-10-30)
GUO, JD
;
FENG, MS
;
GUO, RJ
;
PAN, FM
;
CHANG, CY
Schottky barriers on n-type GaN films grown by low-pressure metalorganic chemical vapor deposition are characterized and derived. A thin Pt or a Pd layer is deposited by electron-gun evaporation to form Schottky contacts in a vacuum below 1X10(-6) Torr. The Schottky barrier heights of Pt on the n-GaN film are determined to be 1.04 and 1.03 eV by current-voltage (C-V) and current density-temperature (J-T) measurements, respectively. Also based on C-V and J-T measurements, the measured barrier height of Pd on n-GaN is 0.94 and 0.91 eV, respectively Schottky characteristics of Pt and Pd observed in the experiment are compared with those of Au and Ti in previous reports. (C) 1995 American Institute of Physics.
STUDY OF SCHOTTKY BARRIERS ON N-TYPE GAN GROWN BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION
(1995-10-30)
GUO, JD
;
FENG, MS
;
GUO, RJ
;
PAN, FM
;
CHANG, CY
Schottky barriers on n-type GaN films grown by low-pressure metalorganic chemical vapor deposition are characterized and derived. A thin Pt or a Pd layer is deposited by electron-gun evaporation to form Schottky contacts in a vacuum below 1X10(-6) Torr. The Schottky barrier heights of Pt on the n-GaN film are determined to be 1.04 and 1.03 eV by current-voltage (C-V) and current density-temperature (J-T) measurements, respectively. Also based on C-V and J-T measurements, the measured barrier height of Pd on n-GaN is 0.94 and 0.91 eV, respectively Schottky characteristics of Pt and Pd observed in the experiment are compared with those of Au and Ti in previous reports. (C) 1995 American Institute of Physics.
ACOUSTIC-EMISSION KAISER EFFECT IN FLY-ASH CEMENT MORTAR UNDER COMPRESSION
(1995-11-01)
TAM, MT
;
WENG, CC
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
Acoustic-emission (AE) technology is considered a potential new testing method to monitor the integrity of concrete materials, This study is devoted to the investigation of the AE Kaiser effect in fly-ash cement mortar (FACM) under uniaxial compression. The major experimental parameters include the amount of cement replaced by fly ash, curing time, compressive strain and stress, loading pattern, and loading rate. The test results showed that the AE Kaiser effect existed in FACM specimens up to 80% of its ultimate strength. Good correlation between the variation of the AE signals and the compressive strains was observed. In addition, the results indicated that the AE Kaiser effect existed in FACM specimen during different curing periods of three, seven, 14, and 28 days. These observations suggested that the AE Kaiser effect has good potential to be used as a new tool to monitor the loading history of concrete materials.
MAGNETOOPTICAL RECORDING CHARACTERISTICS OF (DY,TB)FECO FILMS
(1995-11-01)
HWANG, WK
;
SHIEH, HPD
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
Recording characteristics of (Dy,Tb)FeCo disks were studied. 'Anisotropy dispersion' of rare earth constituents such as Gd, Tb, and Dy qualitatively accounts for domain wall mobility and domain size. Results, obtained in this study, indicated that both coercivity and domain wall mobility play critical role in the magneto-optical recording.
A MODEL TO PREDICT THE SYSTEM PERFORMANCE OF AN ELECTROSTATIC PRECIPITATOR FOR COLLECTING POLYDISPERSE PARTICLES
(1995-11-01)
BAI, HL
;
LU, CS
;
CHANG, CL
;
環境工程研究所
;
Institute of Environmental Engineering
This paper presents a model for predicting the performance of an electrostatic precipitator (ESP) for collecting polydisperse particles. The particle charge was obtained by modifying Cochet's charge equation; the particle size distribution was approximated by a lognormal function; and then the statistic method of moments was employed to obtain a set of the first three moment equations. The continuous evolution of the particle size distribution in an ESP is easily taken into account by the first three moment equations. The performance of this model was validated by comparing its predictions with the existing data available in the literature. Effects of the particle size distribution on the ESP performance were examined, and the results indicated that both overall mass and number efficiencies are lower for inlet particles with a larger mass median diameter and a higher geometric standard deviation. The methodology introduced may be applied to develop design criteria and determine optimal operating conditions of an ESP for improving the collection efficiency of the submicron particles.
EFFECTS OF ELECTRON-PHONON INTERACTION ON EXCITON BINDING-ENERGY IN A QUANTUM-WELL
(1995-11-01)
CHUU, DS
;
WON, WL
;
PEI, JH
;
電子物理學系
;
物理研究所
Using Lee-Low-Pines transformation and perturbative variational method, the effect of electron-phonon interaction on the exciton binding energy in a Ga1-xAlxAs quantum well can be solved analytically. Our results show that the phonon effect on binding energy of heavy-hole exciton is always larger than that of light-hole exciton and the correction of polaron effect on the exciton binding energy in a quantum well cannot be neglected.
A polynomial-perceptron based decision feedback equalizer with a robust learning algorithm
(1995-11-01)
Chang, CH
;
Siu, S
;
Wei, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A new equalization scheme, including a decision feedback equalizer (DFE) equipped with polynomial-perceptron model of nonlinearities and a robust learning algorithm using l(p)-norm error criterion with p < 2, is presented in this paper, This equalizer exerts the benefit of using a DFE and achieves the required nonlinearities in a single-layer net. This makes it easier to train by a stochastic gradient algorithm in comparison with a multi-layer net. The algorithm is robust to aberrant noise for the addressed equalizer and, hence, converges much faster in comparison with the l(p)-norm. A detailed performance analysis considering possible numerical problem for p < 1 is given in this paper. Computer simulations show that the scheme has faster convergence rate and satisfactory bit error rate (BER) performance. It also shows that the new equalizer is capable of approaching the performance achieved by a minimum EER equalizer.
THEORETICAL-STUDY OF 2-FREQUENCY COHERENCE OF MST RADAR RETURNS
(1995-11-01)
CHU, YH
;
CHEN, TY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The theoretical expressions of two-frequency coherence of the MST radar returns from an atmospheric thin layer with sharp boundaries, which embeds within the radar volume and cannot be resolved by conventional radar techniques, are derived in this article. It shows that the derived frequency domain interferometry (FDI) coherence is not only the function of layer thickness and the components of radar wave vector, but also related to the wavenumber power spectrum of refractivity irregularities. A quantitative examination of the derived FDI coherence indicates that the effect of the irregularity power spectrum on FDI coherence is negligible for power law spectral model, while it cannot be ignored for other spectral forms, for example, a Gaussian model. The zenith angle dependence of FDI coherence is also investigated in this article. According to the observations made with Chung-Li VHF radar, it shows that the ratio of the observed FDI coherence at the vertical to that at 17 degrees off-zenith angle is between 1.3 and 2.4. This feature can be illustrated satisfactorily by using the theory developed in this article. The effect of echoing mechanism on FDI coherence is also studied, showing that the expression of FDI coherence derived from the turbulent scattering theory can be treated to be identical to that from the Fresnel reflection theory as long as the condition Delta k/k << 1 is met. This result implies that it seems to be impossible to identify the echoing mechanism of MST radar by using FDI technique. The problem of estimating the thickness of a thin layer having sharp boundaries by using a Gaussian function with the expression of exp (-Delta k(2) sigma(r)(2),2) is also discussed. It suggests that the pertinent formula used for layer thickness estimate is L = 2.364 sigma(r). A comparison of this work with other results is also made in the text.
DIAGNOSIS OF MULTIPLE SENSOR AND ACTUATOR FAILURES IN AUTOMOTIVE ENGINES
(1995-11-01)
HSU, PL
;
LIN, KL
;
SHEN, LC
;
交大名義發表
;
電控工程研究所
Unlike cases where only a single failure occurs, fault detection and isolation of multiple sensor and actuator failures for engines are difficult to achieve because of the interactive effects of the failed components. If faults all appear either in sensors only or in actuators only, many existing residual generators which provide decoupled residual signals can be employed directly to obtain proper fault detection and isolation. However, when both sensor and actuator failures occur at the same time, their mutual effects on residuals make fault isolation particularly difficult, Under such circumstances, further decision logic is required. In this paper, we propose a hexadecimal decision table to relate all possible failure patterns to the residual code. The residual code is obtained through simple threshold testing of the residuals, which are the output of a general scheme of residual generators. The proposed diagnostic system incorporating the hexadecimal decision table has been successfully applied to automotive engine sensors and actuators in both simulation and experimental analyses. Enhancement of the present diagnostic performance by implementing an additional sensor is also described.