Browsing by Issue Date, starting with "1995-10-22"

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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.
A new subliminal channel based on Fiat-Shamir's signature scheme
(1995-11-01)
Chen, CY
;
Chang, CC
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
This paper constructs a subliminal channel in a RSA-like variant of the Fiat-Shamir signature scheme to transfer any secret information. The proposed subliminal channel, unlike that in El-Gamal signature scheme, can avoid the serious shortcoming that a subliminal receiver can undetectably forge a signer's signature. In addition, our channel also overcomes almost all shortcomings from which the subliminal channel in El-Gamal signature scheme suffer.
AREA COMPUTATION BY COORDINATES
(1995-11-01)
SHIH, TY
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
;
Department of Civil Engineering
Area computation by coordinates has become the conventional method for application purposes. The structure and forms of the equations used for this method are investigated in this study. Various factors that result in a negative value of the computed area are also explored. Examples are provided to illustrate that the value of area is independent of the location of origin. If sign conventions are followed faithfully in various quadrants, the numerical answer will be the same. Traditionally,:a negative area is considered as meaningless. This article demonstrated some potentially useful information provided by the sign of the area. To improve accuracy, two interpolation schemes, cubic spline and Akima's 1970 quasi-Hermite spline, are tested with numerical examples. For the limited examples experienced, both algorithms have demonstrated the potential for accuracy improvement. However, there is no conclusive evidence on which algorithm is the better one.
SCALING BEHAVIORS OF PINNING IN POLYMERIZATION-INDUCED PHASE-SEPARATION
(1995-11-01)
CHEN, WJ
;
CHEN, SH
;
光電工程研究所
;
Institute of EO Enginerring
A dynamical model for the phase separation induced by polymerization has been developed and studied by Monte Carlo simulations. The model shows a pinning of the structure factor and exhibits scaling relations and exponents. We propose a theoretical argument to predict the pinning exponents, which are in agreement with simulation values. For a different concentration ratio of bifunctional to tetrafunctional monomers, the simulation results are also found to be consistent with the theoretical predictions.
The correlation effects on service control point response time
(1995-11-01)
Wey, JH
;
Sun, LF
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
As the centralized database for the integration across multiple wireless tiers and wireline access, traffic design considerations for SCP performance measurement are of great important in the personal communications era. By neglecting the effect of disk access time, the SCP response time R includes the SCP processing time P and signalling link delay L only. A bivariate normal distribution has been proposed for modelling (P, L) such that some statistical estimations of L given P can be conveniently obtained in different combination of SCP processing load and link utilization. Further, the correlation effects of (P, LP = p) on R are investigated. After a Turkey one degree of freedom test with one observation of mu(LP=p) per treatment (n = 1) under different normalized processing times and correlations, the two-factor ANOVA model becomes an interaction model without pure error effects due to the computed F* values being significantly greater than the critical F(0.95; 1, 11). Besides, rejection threshold criteria of SCP response time with minimum loss rate (0.01 per cent) of messages are proposed to ensure a good service quality of SCP.
ON CORRESPONDENCE, LINE TOKENS AND MISSING TOKENS
(1995-11-01)
LEE, CH
;
JOSHI, A
;
資訊工程學系
;
Department of Computer Science
In this article, the authors expand on some of their previous work on correspondence and propose a system that can correspond in the presence of both point and line tokens, or a mix of them. It can also work if some tokens present in one frame are not present in the other. The proposed algorithm is an amalgamation of reductionist and holist paradigms. We establish that properties which remain invariant for whole image sequences and sequences consisting of corresponding parts from each image frame can be used to establish correspondence. Extensive computer simulation results on synthesised data as well as real image sequences are presented to validate our claims.
DETERMINATION OF J(C) FOR A POLYCARBONATE (PC) POLY(BUTYLENE TEREPHTHALATE) (PBT) BLEND-BASED ON THE ANALYSES OF MULTIPLE-SPECIMEN J-R CURVES
(1995-11-01)
LU, ML
;
CHANG, FC
;
應用化學系
;
Department of Applied Chemistry
Various regression models and data windows have been used to examine the multiple-specimen J integral analysis to provide the best estimate of fracture toughness. The linear regression model (similar to ASTM E813-81) results in the least accuracy in the data fitting and is highly sensitive to the data window. The power law model (similar to ASTM E813-87) gives a better data fitting and is less sensitive to the data window. The polynomial regression models with higher orders (n = 3 and 4) give the best data fitting. True crack initiation occurs gradually rather than as an abrupt event, and therefore the critical J strictly based on initiation could be in error. ASTM E813-81 based on the theoretically predicted blunting line tends to give an underestimated J(c). The power law approach of ASTM E813-87 indeed provides a better data fitting but suffers the disadvantage of an overestimated J(c) owing to the 0.2 mm offset line. The 0.1 mm offset line approach proposed here results in the most consistent J(c) regardless of the regression models and data windows selected.
EXPERIMENTAL CHARACTERIZATION OF THE VIBRATIONAL BEHAVIOR OF A FLUID-FILLED THIN SHELL FOR THE PURPOSE OF RESPONSE ESTIMATION
(1995-11-01)
BAI, MR
;
LIN, YY
;
機械工程學系
;
Department of Mechanical Engineering
Experimental techniques are proposed for developing a model to estimate structural vibrations induced by internal acoustic pressure at low frequencies. In these methods, the acoustic field and the structure are treated as a coupled system with the acoustic loading effect taken into account. The response model between the internal pressure and the surface vibration is established by a modified modal test on the coupled system. Experiments are performed to investigate the surface vibrations of a closed steel cylindrical shell excited by a loudspeaker inside. The experimental results show that developed techniques provide accurate estimation for the acoustically induced vibrations. (C) 1995 Acoustical Society of America.