Browsing by Issue Date, starting with "1993-11-15"

Now showing 1 - 20 of 89417

VISIBLE INGAP/LNGAAIP QUANTUM-WELL TOP SURFACE-EMITTING LASER-DIODES
(1993-11-15)
TAI, KC
;
HUANG, KF
;
WU, CC
;
WYNN, JD
;
電子物理學系
Vertical cavity top surface emitting lasers emitting near 0.67 mu m visible spectral region were fabricated by one-step low pressure metalorganic vapor phase deposition technique. The lasers used four 80-Angstrom-thick InGaP/InGaAlP quantum wells active region, sandwiched between two Al0.5Ga0.5As/AlAs distributed Bragg reflectors. Room temperature pulsed threshold current was 10 mA for 15 mu m diam devices.
EFFECT OF POLYCARBONATE MOLECULAR-WEIGHT ON POLYMER BLENDS OF POLYCARBONATE AND ABS
(1993-11-20)
WU, JS
;
SHEN, SC
;
CHANG, FC
;
交大名義發表
;
應用化學系
The melt viscosity of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends relative to PC is significantly lower, even lower than that of pure ABS in some compositions. Annealing above the T(g) of PC coalesces and coarsens phase structure in core and skin regions. Increase in the molecular weight of PC in PC/ABS blends results in low-temperature fracture toughness improvement but suffers from the disadvantage of higher melt viscosity. The selection of PC in PC/ABS blends must be a compromise between the toughness advantages of higher PC molecular weight and the disadvantages of higher melt viscosity. (C) 1993 John Wiley & Sons, Inc.
MODIFIED CHANG-HWANG-WU ACCESS-CONTROL SCHEME
(1993-11-25)
HWANG, MS
;
YANG, WP
;
CHANG, CC
;
資訊工程學系
;
Department of Computer Science
It is found that some security classes in the Chang-Hwang-Wu access control scheme can be combined to derive the secret key of their immediate ancestor in some cases. Some slight modifications to the proposed scheme to enhance the security levels are also given.
DESIGN OF HOPFIELD-TYPE ASSOCIATIVE MEMORY WITH MAXIMAL BASIN OF ATTRACTION
(1993-11-25)
CHANG, JY
;
WU, CC
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
A method is described for enlarging as much as possible the basin of attraction of a Hopfield-type associative memory. The proposed learning rule, a minimum-overlap learning algorithm that includes a threshold parameter, enables a Hopfield-type associative memory to be designed so that the memory will have a maximal basin of attraction. A technique that diminishes the effect of the threshold on the minimum-overlap learning algorithm is devised. Simulation results show that the basin of attraction constructed by the proposed method is indeed larger than that constructed by several well known methods.
TEMPERATURE-DEPENDENT RAMAN-SPECTRA OF THIN-FILM C60/C70 FULLERENES AND ITS IMPLICATION IN SUPERCONDUCTOR
(1993-12-01)
LO, KL
;
LEE, MC
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
Thin filMS Of C60, and C70 fullerenes were studied by Raman scattering, from 295 to 10 K. As many as 48(42) peaks at 10(80) K, instead of 2Ag+8Hg modes in C60, and also up to 65 lines in C70 at 80 K are observed. Room temperature shoulders and mode-splitting are confirmed. They are due to new phases with the reduced symmetry at low temperatures and freezing of buckyball rotation. Besides, laser heating revealed new structures that may affect superconducting property.
生日派對
(1993-12-01)
管管
RANDOM-SAMPLING THRESHOLDING - A NEW APPROACH TO MULTILEVEL THRESHOLDING
(1993-12-01)
YIN, PY
;
CHEN, LH
;
資訊工程學系
;
Department of Computer Science
In this paper, a new approach to multilevel thresholding is proposed. First, the approach uniformly spreads some coarse thresholds over the gray-level range. Then, an adjusting process is applied repeatedly until a certain stopping criterion is reached. In the process, some pixels are first randomly sampled. Then, those coarse thresholds are finely adjusted according to the distribution of their neighborhood in the histogram formed by the randomly sampled pixels. The proposed method can automatically determine the number of thresholds. Furthermore, if the number of the resulting thresholds is not sufficient under a certain sense, the proposed method can be iteratively applied, based on the previous results, to get more thresholds. Experimental results also show that the performance of the proposed method is comparable to that of the recent method presented by Lim.
FABRICATION AND PROPERTIES OF ALUMINO-BORO-SILICATE GLASS-CERAMIC SYSTEMS
(1993-12-01)
CHIOU, BS
;
TZENG, JM
;
DUH, JG
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In current microelectronics packaging applications, low-temperature fired substrates with low dielectric constant are required. Formulations of SiO2, B2O3, Al2O3, and CaO have been used as substrate materials which can be sintered as low as 1000-degrees-C in air. The electrical behaviour, thermal expansion coefficient, and mechanical property of the fabricated substrate materials are evaluated. The as-sintered substrates possess the following characteristics: low dielectric constant of 4-5 at 1 MHz; a loss factor smaller than 0.2% at 1 MHz; and a thermal expansion of 3.57 x 10(-6)-degrees-C-1 which is very close to that of silicon (3.5 x 10(-6)-degrees-C-1).
SENSITIVITY AND UNCERTAINTY ANALYSIS OF A SEDIMENT TRANSPORT MODEL - A GLOBAL APPROACH
(1993-12-01)
CHANG, CH
;
YANG, JC
;
TUNG, YK
;
土木工程學系
;
Department of Civil Engineering
Computerized sediment transport models are frequently employed to quantitatively simulate the movement of sediment materials in rivers. In spite of the deterministic nature of the models, the outputs are subject to uncertainty due to the inherent variability of many input parameters in time and in space, along with the lack of complete understanding of the involved processes. The commonly used first-order method for sensitivity and uncertainty analyses is to approximate a model by linear expansion at a selected point. Conclusions from the first-order method could be of limited use if the model responses drastically vary at different points in parameter space. To obtain the global sensitivity and uncertainty features of a sediment transport model over a larger input parameter space, the Latin hypercubic sampling technique along with regression procedures were employed. For the purpose of illustrating the methodologies, the computer model HEC2-SR was selected in this study. Through an example application, the results about the parameters sensitivity and uncertainty of water surface, bed elevation and sediment discharge were discussed.
INDUCTION AND DEDUCTION FOR AUTONOMOUS NETWORKS
(1993-12-01)
LIN, YD
;
GERLA, M
;
資訊工程學系
;
Department of Computer Science
The key issues in network management are the representation and sharing of management information and the automatic management mechanisms based on the underlying information infrastructure. In this paper, we propose a framework, which operates on the standard MIB's and CMIP, for the network management system with learning and inference as its management engines. In addition to the general domain knowledge, patterns related to the managed network are learned to enhance the understanding of the network and refine the knowledge base. Facts in object-oriented databases or queries from management applications trigger the inference process on logical rules which are either prespecified knowledge or learned network patterns. Forward inference drives prediction and control, while backward inference directs diagnosis and supports view abstraction. A case study on ATM network topolgy tuning is presented.
STRUCTURE OF THE NEW TLBA2PRCU2O7-X BY RIETVELD ANALYSIS
(1993-12-01)
LEE, TJ
;
FUN, HK
;
WANG, A
;
CHOU, CH
;
LAI, CC
The crystalline structure of new TlBa2PrCu2O7-y was obtained at room temperature from X-ray powder diffraction with CuKalpha radiation using Rietveld analysis. TlBa2PrCu2O7-x is semiconducting at room temperature with a TlBa2CaCu2O7 type (1212) structure (space group P4/mmm) and cell parameters a = 3.91836(3) angstrom, c = 12.5498(2) angstrom. The structure was refined for 15 parameters to R(wp) = 6.89 %, R(p) = 5.09 % for 6323 step intensities and R(b) = 13.24 % for 138 reflections.
DESIGN OF LAMINATED COMPOSITE PLATES FOR MAXIMUM SHEAR BUCKLING LOADS
(1993-12-01)
CHANG, RR
;
CHU, KH
;
KAM, TY
;
交大名義發表
;
機械工程學系
The optimal lamination arrangements of laminated composite plates with maximum shear buckling loads are studied via a multi-start global optimization technique. A previously proposed shear deformable finite element is used to evaluate the positive and negative shear buckling loads of laminated composite plates in the optimal design process. Optimal lay-ups of thin as well as moderately thick composite plates with global maximum positive or negative shear buckling loads are determined utilizing the multi-start global optimal design technique. A number of examples of the optimal shear buckling design of symmetrically and antisymmetrically laminated composite plates with various material properties, length-to-thickness ratios, aspect ratios and different numbers of layer groups are given to illustrate the trends of optimal layer orientations of the plates. Since the existence of in-plane axial forces is possible, the effects of axial compressive load on the optimal layer orientations for maximum shear buckling load are also investigated.
DECENTRALIZED ROBUST-CONTROL OF DECOMPOSED UNCERTAIN INTERCONNECTED SYSTEMS
(1993-12-01)
CHENG, CF
;
WANG, WJ
;
LIN, YP
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a new design technique of decentralized robust controllers for a class of uncertain interconnected system is provided. The interconnection matrices and the uncertainties of the system are decomposed into a matched and a mismatched portions. Since the matched portion can always be compensated by feedback controls, this new technique can provide local controllers to withstand strong interconnections and large uncertainties. The relations among local feedback gains, uncertainty bounds, and interconnection strength are established to aid the robust controller design. A practical system with simulation results is given to exemplify the implementation of the controller design technique.
HYDROGEN-ATOM IN A HIGH MAGNETIC-FIELD
(1993-12-01)
CHUU, DS
;
LEE, YK
;
物理研究所
;
Institute of Physics
The low-lying energy levels of a hydrogen atom in a uniformly strong magnetic field B (B < 10(10) G) are calculated in a simple perturbative variational approach which combines the spirit of the variational principle and the conventional pertubation method. The total Hamiltonian is separated into four parts: a one-dimensional hydrogen-atom system; a two-dimensional harmonic-oscillator system; a z-component angular-momentum operator; and a perturbation part which contains an undetermined variable parameter but is independent of B. The first three parts can be solved exactly. The variational parameter introduced in the Hamiltonian can be determined by requiring the energy-correction expansion to converge as fast as possible. It is found that our calculated ground-state energy is in good agreement with those obtained by the previous works that used the wave-function-expansion approach for high magnetic fields up to gamma = 7 (i.e., 10(10) G for atoms).
OPTICALLY CLEAR SIMULTANEOUS INTERPENETRATING POLYMER NETWORKS BASED ON POLY(ETHYLENE GLYCOL)DIACRYLATE AND EPOXY .2. KINETIC-STUDY
(1993-12-01)
LIN, MS
;
JENG, KT
;
HUANG, KY
;
SHIH, YF
;
交大名義發表
Simultaneous interpenetrating polymer networks (SINs) based on diglycidyl ether of bisphenol A (DGEBA) and poly(ethylene glycol) diacrylate (PEGDA) in weight ratios of 100/0, 50/50, and 0/ 100 were blended and cured simultaneously by using benzoyl peroxide (BPO) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 45, 55, 63, and 70-degrees-C. Concentration changes for both the epoxide and C = C bond were monitored with FTIR. A rate expression for DGEBA cure kinetics was established with a model reaction of phenyl glycidyl ether (PGE) and benzylamine. Experimental results revealed that lower rate constants and higher activation energy for the SIN were found, compared with those for the constituent DGEBA and PEGDA network formation. A model of network interlock was proposed to account for this phenomenon. During simultaneous cure of DGEBA and PEGDA, the interlock (mutual entanglement) between DGEBA and PEGDA networks provided a sterically hindered environment, which subsequently increased the activation energy and reduced cure rates for both DGEBA and PEGDA. (C) 1993 John Wiley & Sons, Inc.
BOLOMETRIC RESPONSE OF SUPERCONDUCTING YBA2CU3O7-X MICROBRIDGES
(1993-12-01)
HUANG, CJ
;
LIU, RS
;
TSENG, TY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
High-T(c) superconducting bolometers have been presented by using YBa2Cu3O7-x films irradiated an LED source with an 0.94 um wavelength. Using static irradiations, the response occurring in the resistive transition region has been shown and the response mechanism has been studied. A thermal fluction on flux creep behavior can be employed to illustrate the nonlinearly optical I - V characteristics in the low resistive region. However, a dissipative mechanism of flux flow should be used in explaining the best response which reveals a linearly I - V relation in the higher-resistance region. The responsivity examined by a 2 Hz dynamic signal with 0.15 mW is 77 V/W.
OPTIMAL SCHEDULING IN FILM PRODUCTION TO MINIMIZE TALENT HOLD COST
(1993-12-01)
CHENG, TCE
;
DIAMOND, JE
;
LIN, BMT
;
資訊工程學系
;
Department of Computer Science
The problem of minimizing the cost due to talent hold days in the production of a feature film is considered. A combinatorial model is developed for the sequencing of shooting days in a film shoot. The problem is shown to be strongly NP-hard. A branch-and-bound solution algorithm and a heuristic solution method for large instances of the problem (15 shooting days or more) are developed and implemented on a computer. A number of randomly generated problem instances are solved to study the power and speed of the algorithms. The computational results reveal that the heuristic solution method is effective and efficient in obtaining near-optimal solutions.
3-SUBSTITUTED 2-CYCLOPENTENONES FROM CYCLOPENTADIENES
(1993-12-01)
LIN, CC
;
HSIA, KS
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WU, HJ
;
應用化學系
;
Department of Applied Chemistry
Oxidation of cyclopentadienes 1a-1j, which were prepared by alkylation of cyclopentadienyl anion with the corresponding alkyl bromides, with pyridinium chlorochromate (PCC) gave the 2-cyclopentenones 2a-2j respectively in 10-15% yields. Reaction of 3 and 5 with PCC gave the spiro compounds 4 and 6 respectively in 75-80% yields.
MORPHOLOGY AND ADHESION STRENGTH IN ELECTROLESS CU METALLIZED ALN SUBSTRATE
(1993-12-01)
CHANG, JH
;
DUH, JG
;
CHIOU, BS
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The metallization of aluminum nitride substrates by electroless copper plating is investigated. The AIN substrate is etched by 4% NaOH to study the correlation between the adhesion strength and the surface roughness of etched AIN substrate. Both the as-received nonpolished and then polished AIN are employed herein. For the nonpolished substrate, the adhesion strength increases from 130 kg/cm2 for the sample with an average surface roughness of 0.2 mum to 230 kgf/cm2 for the one with an average surface roughness of 0.82 mum. For the polished substrate, the adhesion strength reaches 271 kg/cm2 with a surface roughness of 0.19 mum. Mechanical interlocking is the major cause for the adhesion strength between the Cu and AIN substrates. The polished substrate followed by etching could form fine cavities on the AIN surface, and the microetching effect results in a stronger mechanical interlocking, which increase the adhesion strength.
THE EFFECTS OF H-2-O-2-PLASMA TREATMENT ON THE CHARACTERISTICS OF POLYSILICON THIN-FILM TRANSISTORS
(1993-12-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
奈米中心
The effects of H-2-plasma followed by O-2-plasma treatment on n-channel polysilicon TFT's were investigated. It was found that the H-2-O-2-plasma treatment is more effective in passivating the trap states of polysilicon films than do the H-2-plasma treatment only or the O-2-plasma treatment only. Hence, it is more effective in improving the device performance on the subthreshold swing, carrier mobility and the current ON/OFF ratio. It is also found that thermal annealing on plasma-treated devices increases the deep states but has no effect on the tail states of the devices.