Browsing by Issue Date, starting with "1994-11-14"

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EFFECT OF POLY(VINYLIDENE FLUORIDE) ON THE IONIC-CONDUCTIVITY AND MORPHOLOGY OF PEO-SALT POLYMER ELECTROLYTES
(1994-11-14)
WHANG, WT
;
YANG, LH
;
FAN, YW
;
交大名義發表
;
材料科學與工程學系
The high dielectric constant polymer poly (vinylidene fluoride) (PVDF) was blended with PEO-salt polymer electrolytes to improve their ionic conductivity. PVDF did improve the room-temperature ionic conductivity of the polymer electrolytes PEO-LiCF3CO2 and PEO-LiBF4, and the ionic conductivity at room temperature went up one order of magnitude with 10(-5)S/cm for LIB4M-PF4 being the most prominent. PVDF exhibited strong effects on the ionic conductivity and morphology of the polymer electrolytes, such as weakening the association of poly (ethylene oxide) (PEO) with the salt, hindering the formation of the PEO-salt complex, enlarging the crystalline PEO phase in LIAnM-PFm polymer electrolytes, and reducing the crystalline PEO phase in LIBnM-PFm polymer electrolytes. Both LIA4M-PF4 and LIB4M-PF4 polymer electrolytes formed a new PEO-PVDF-salt complex. The new complex in the former was crystalline, but that in the latter was amorphous. (C) 1994 John Wiley and Sons, Inc.
FREE-CARRIER ABSORPTION IN N-TYPE PIEZOELECTRIC SEMICONDUCTOR-FILMS
(1994-11-14)
WU, CC
;
LIN, CJ
;
應用數學系
;
電控工程研究所
;
Department of Applied Mathematics
Free-carrier absorption in n-type GaAs films has been investigated for the case where the free carriers are confined in a quasi-two-dimensional semiconducting structure with a non-parabolic energy band of electrons. It is assumed that the carriers in semiconductors are scattered by acoustic phonons via firstly the deformation-potential coupling and secondly the piezoelectric coupling. Results show that the free-carrier absorption coefficient depends upon the polarization of the electromagnetic radiation relative to the direction normal to the quasi-two-dimensional structure, the film thickness, the photon frequency and the temperature of the semiconductors. The free-carrier absorption coefficient could be complex owing to the interaction of photons, phonons and conduction electrons in piezoelectric semiconductors. Firstly, when the deformation-potential coupling is dominant, the absorption coefficient increases with decreasing photon frequency and increasing temperature for the radiation field,polarized parallel and perpendicular to the layer plane. It is also shown that the absorption coefficient increases with decreasing film thickness. Secondly, when the piezoelectric scattering is dominant, the absorption coefficient increases with decreasing photon frequency and decreasing film thickness for the radiation field polarized parallel and perpendicular to the layer plane. However, the absorption coefficient increases with increasing temperature for the radiation field polarized parallel to the layer plane while, for the radiation field polarized perpendicular to the layer plane, the absorption coefficient increases with decreasing temperature.
TUNABLE PICOSECOND PULSE GENERATION FROM AN ACTIVELY MODE-LOCKED LASER-DIODE ARRAY WITH INTRACAVITY CHIRP COMPENSATION
(1994-11-15)
WANG, CL
;
PAN, CL
;
光電工程學系
;
Department of Photonics
Wavelength-tunable picosecond pulses have been generated from an actively mode-locked laser diode array in an external cavity. The cavity incorporated a folded dispersive delay line which provided functions of pulse compression, wavelength tuning and spatial mode control. By varying the group velocity dispersion inside the cavity, the laser pulse width was intra-cavity compressed from 44 to 25 ps. The laser wavelength was tuned from 794 to 806 nm by translating a stripe end mirror horizontally with respect to the optical axis. The side mode suppression ratio was better than 10 dB over the entire tuning range. The spatial mode was a quasi-single-lobe.
LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION OF SILICON-CARBIDE THIN-FILMS FROM HEXAMETHYLDISILANE
(1994-11-15)
CHIU, HT
;
HSU, JS
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Silicon carbide thin films were grown by low pressure chemical vapor deposition using hexamethyldisilane Me3SiSiMe3 as the single-source precursor. Deposition of uniform thin films on Si(1 1 1) substrates was carried out at temperatures 1123-1323 K in a hot-wall reactor. The growth rates were 0.9-55 nm min-1 depending on the conditions employed. Estimated energy of activation is 110 kJ mol-1. Bulk elemental composition of the thin films, studied by an electron probe X-ray microanalyzer, is best described as SiC(x) (x = 0.8-2.3). The Si/C ratio increased with increasing temperature of deposition. The films were cubic polycrystals, a = 0.435-0.438 nm, as indicated by scanning transmission electron microscopy, electron diffraction and X-ray diffraction. The lattice parameter decreased with increasing temperature of deposition. Elemental distribution within the films, studied by Auger depth profiling and X-ray photoelectron spectroscopy, was uniform. Gas phase products H-2, CH4, C2H4, Me3SiH and Me4Si were identified and possible reaction pathways were proposed.
EFFECTS OF AN IMPURITY ON THE CONDUCTANCE AND THERMOPOWER OF A SADDLE-POINT-POTENTIAL QUANTUM POINT-CONTACT
(1994-11-15)
CHU, CS
;
CHOU, MH
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
AS PRECIPITATE REDISTRIBUTION IN SI DELTA-DOPED LOW-TEMPERATURE GAAS
(1994-11-15)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
NONVARIATIONAL APPROACH TO IMPURITY STATES IN QUANTUM WIRES
(1994-11-15)
JAN, JF
;
LEE, YC
;
CHUU, DS
;
電子物理學系
;
Department of Electrophysics
STRUCTURAL DESIGN UNDER MULTIOPTIMAL CONSIDERATION
(1994-11-17)
CHIN, JH
;
TSENG, GT
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
The purpose of this study is to propose a concept which takes both the total weight and the response of a structure into consideration and the critical point is applied to search the equivalent minimum value for the optimization problem. It also used the criteria for the decomposition of the system. By these criteria, optimal design could be performed for any typical structure without having recourse to the entire system. An efficient calculation has been established for a system in an optimal design process.
INFLUENCE OF X-VALLEY SUPERLATTICE ON ELECTRON BLOCKING BY MULTIQUANTUM BARRIERS
(1994-11-21)
YEN, ST
;
LEE, CP
;
TSAI, CM
;
CHEN, HR
;
電子工程學系及電子研究所
SOME EXACT RESULTS FOR THE DIFFUSION-COEFFICIENTS OF MAPS WITH PRUNING CYCLES
(1994-11-21)
TSENG, HC
;
CHEN, HJ
;
LI, PC
;
LAI, WY
;
CHOU, CH
For a family of piecewise linear maps, we consider several interesting cases in which the symbolic dynamics is described in terms of a restricted grammar. However, their diffusion coefficients can be determined analytically through appropriate cycle expansions.
此番抽身去不見詩人回
(1994-11-22)
將穆
CONSTRUCTION OF DYNAMIC THRESHOLD SCHEMES
(1994-11-24)
SUN, HM
;
SHIEH, SP
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
An (m,n) threshold scheme is to decompose a shared secret into n shares in such a way that the shared secret cannot be reclaimed unless any m shares are collected. A new dynamic threshold scheme that allows the shared secret to be updated without changing the shares is proposed.
ON DYNAMIC THRESHOLD SCHEMES
(1994-11-25)
SUN, HM
;
SHIEH, SP
;
資訊工程學系
;
Department of Computer Science
An (m, n) threshold scheme is to decompose the master key K into n secret shadows in such a way that the master key K cannot be reclaimed unless any m shadows are collected. However, any m-1 or fewer shadows provide absolutely no information about K. In 1989, Laih et al. proposed the concept of dynamic threshold schemes which allow the master key to be updated without changing the secret shadows. However, the perfect dynamic threshold scheme, which provides perfect secrecy though the master key is allowed to be changed, has not been proposed. Nor has any paper shown the existence of perfect dynamic threshold schemes. In this paper, we prove that perfect dynamic threshold schemes do not exist when their master keys need be updated [log(2)Llog(2)K] times or more without changing the secret shadows, where L is the secret shadow space and K is the master key space. Furthermore, we propose an perfect dynamic threshold scheme which allows its master key to be updated once without changing the secret shadows.
BLENDS OF POLYETHYLENE TEREPHTHALATE WITH CO[POLY(ETHYLENE TEREPHTHALATE-P-OXYBENZOATE)] .1. CRYSTALLIZATION KINETICS BY DSC STUDY
(1994-11-28)
OU, CF
;
LIN, CC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The dynamic and isothermal crystallization behaviors of polyethylene terephthalate (PET) blended with two types of co[poly(ethylene terephthalate-p-oxybenzoate){ copolyesters with different compositions, i.e., POB/PET = 20/80 (P28) and POB/PET = 80/20 (P82), has been studied by using differential scanning calorimetry (DSC). Both of these copolyesters in 10 wt % increase crystallization rate of PET in a manner similar to that of a nucleating agent. It is found that sample P28, which is an isotropic copolyester, accelerates the crystallization rate more significantly than that of P82, which is a thermotropic copolyester. The Avrami exponents n and rate constants k of these samples based on DSC studies were obtained in order to discuss the crystallization kinetics of PET accelerated by these copolyesters. The crystallization rate of the blends is also increased by 8 min blending due to the increased uniformity of the copolyester dispersed in the PET matrix. (C) 1994 John Wiley & Sons, Inc.
ONLINE HANDWRITTEN CHINESE CHARACTER-RECOGNITION VIA A FUZZY ATTRIBUTE REPRESENTATION
(1994-12-01)
CHEN, JW
;
LEE, SY
;
工學院
;
College of Engineering
Chinese characters are constructed by strokes according to structural rules. Therefore, the geometric configurations of characters are important features for character recognition. In handwritten characters, stroke shapes and their spatial relations may vary to some extent. The attribute value of a structural identification is then a fuzzy quantity rather than a binary quantity. Recognizing these facts, we propose a fuzzy attribute representation (FAR) to describe the structural features of handwritten Chinese characters for an on-line Chinese character recognition (OLCCR) system. With a FAR, a fuzzy attribute graph for each handwritten character is created, and the character recognition process is thus transformed into a simple graph matching problem. This character representation and our proposed recognition method allow us to relax the constraints on stroke order and stroke connection. The graph model provides a generalized character representation that can easily incorporate newly added characters into an OLCCR system with an automatic learning capability. The fuzzy representation can describe the degree of structural deformation in handwritten characters. The character matching algorithm is designed to tolerate structural deformations to some extent. Therefore, even input characters with deformations can be recognized correctly once the reference dictionary of the recognition system has been trained using a few representative learning samples. Experimental results are provided to show the effectiveness of the proposed method.
LEARNING CONCEPTS IN PARALLEL BASED UPON THE STRATEGY OF VERSION SPACE
(1994-12-01)
HONG, TP
;
TSENG, SS
;
資訊工程學系
;
Department of Computer Science
In this paper, we have attempted to apply the technique of parallel processing to concept learning. A parallel version-space learning algorithm based upon the principle of divide-and-conquer is proposed. Its time complexity is analyzed to be O(k log(2) n) with n processors, where n is the number of given training instances and k is a coefficient depending on application domains. For a bounded number of processors in the real situations, a modified parallel learning algorithm is then proposed. Experimental results are then performed on a real learning problem, showing our parallel learning algorithm works and being quite consistent with results of theoretic analysis. We have finally concluded that when the number of training instances is large, it is worth learning in parallel because of its faster execution.
REALIZATIONS OF HIGH-ORDER SWITCHED-CAPACITOR FILTERS USING MULTIPLEXING TECHNIQUE
(1994-12-01)
WU, CY
;
BOR, JC
;
JENG, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new SC design methodology using multiplexing technique is proposed to realize arbitrary high-order filters. In this methodology, the filter transfer function is transformed as the combination of biquads and their outputs are computed sequentially by the multiplexing SC biquad circuit. Four basic function SC circuits are introduced and a filter can be implemented by various combinations of these circuits, This makes the proposed method more versatile and practical. Because of the efficient use of multiplexing techniques, the realized high-order filters have less op-amps, switches, and capacitors, and thus small chip area, but at the cost of increasing clock phases. An eighth-order Butterworth low-pass filter design example is presented to demonstrate how to apply the proposed method to the design of high-order filters. Moreover, an eighth-order low-pass filter has been designed and fabricated in 1.2 mu m CMOS double-poly double-metal process. Both computer simulation and experimental results have successfully verified the function correctness and the performance of the proposed design method.
PHASE-CONJUGATION BY 4-WAVE-MIXING IN SINGLE-MODE FIBERS
(1994-12-01)
WU, WS
;
YEH, PC
;
CHI, S
;
光電工程學系
;
Department of Photonics
We present an exact solution to the coupled-mode equations, governing four-wave mixing in single-mode fibers, under the perfect phase-matching condition. The solution accounts for pump depletion and fiber absorption. Optimum length of fiber is derived and phase conjugation efficiency is calculated and discussed. The calculated results are in good agreement with the reported experimental results.
ON THE APPLICATION OF THE (1)-INVERSE TO THE DESIGN OF GENERAL STRUCTURED UNKNOWN INPUT OBSERVERS
(1994-12-01)
CHANG, SK
;
HSU, PL
;
電子工程學系及電子研究所
;
電控工程研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a concise and straightforward formulation of the unknown input observer (UIO) problem based on the general structured observer. By employing the simplest generalized inverse of matrices, the {1}-inverse, we develop constructive design procedures for the UIO design that provide necessary and sufficient conditions for both full-order and reduced-order general structured UIOs. Moreover, corresponding configurations for continuous-time systems are also derived, and consequently this paper renders the complete solutions for general structured UIO design. Furthermore, we show that the general structured UIO is structurally and numerically equivalent to the UIO in the configuration of Luenberger observer. Examples are included to illustrate the validity of the proposed methodology.
FINDING THE MOST VITAL EDGES WITH RESPECT TO THE NUMBER OF SPANNING-TREES
(1994-12-01)
TSEN, FSP
;
SUNG, TY
;
LIN, MY
;
HSU, LH
;
MYRVOLD, W
A most vital edge of a graph (w.r.t. the spanning trees) is an edge whose deletion most drastically decreases the number of spanning trees. We present an algorithm for determining the most vital edges based on Kirchoff's matrix-tree theorem whose asymptotic time-complexity can be reduced to that of the fastest matrix multiplication routine, currently 0(n(2.376)). The foundation for this approach is a more general algorithm for directed graphs for counting the rooted spanning arborescences containing each of the arcs of a digraph. A network can be modeled as a probabilistic graph. Under one such model proposed by Kel'mans, the all-terminal network reliability, maximizing the number of spanning trees is critical to maximizing reliability when edges are very unreliable. For this model, the most vital edges characterize the locations where an improvement of the reliability of the link most improves the reliability of the network.