Browsing by Issue Date, starting with "1994-11-21"

Now showing 1 - 20 of 88033

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
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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
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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
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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
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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
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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
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SUNG, TY
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LIN, MY
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HSU, LH
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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.
AN INVESTIGATION INTO GEOMETRICALLY NONLINEAR-ANALYSIS OF RECTANGULAR LAMINATED PLATES USING THE HIERARCHICAL FINITE-ELEMENT METHOD
(1994-12-01)
HAN, WM
;
PETYT, M
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HSIAO, KM
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機械工程學系
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Department of Mechanical Engineering
The geometrically nonlinear analysis of laminated composite rectangular plates is studied using the hierarchical finite element method (HFEM). The derivation of the equilibrium equations and tangential stiffness matrix are given. Symbolic computation is used to calculate the high-order polynomial integrals needed to establish the stiffness matrices. The Newton-Raphson method is used in the iterative procedure. The convergence property and the numerical stability of the method are discussed. The influence of in-plane displacements on the geometrically nonlinear deformation is also discussed. The results of static analyses indicate that the extension of HFEM to geometrically nonlinear analysis of laminated rectangular plates is very successful. It is believed that this scheme can be easily applied to geometrically nonlinear dynamic analysis of laminated plates.
NEURAL-NETWORK-BASED F0 TEXT-TO-SPEECH SYNTHESIZER FOR MANDARINE
(1994-12-01)
HWANG, SH
;
CHEN, SH
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電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
A neural-network-based approach to synthesising F0 information for Mandarin text-to-speech is discussed. The basic idea is to use neural networks to model the relationship between linguistic features, extracted from input text and parameters representing the pitch contour of syllables. Two MLPs are used to separately synthesise the mean and shape of pitch contour, using different linguistic features. A large set of utterances is employed to train these MLPs using the well known back-propagation algorithm. Pronunciation rules for generating F0 information are automatically learned and implicitly memorised by the MLPs. In the synthesis, parameters representing the mean and shape of the pitch contour of each syllable are generated using linguistic features extracted from the given input text. Simulation results confirmed that this is a promising approach for F0 synthesis. The resulting synthesised pitch contours of syllables match well with their original counterparts. Average root mean square errors of 0.94 ms/frame and 1.00ms/frame were achieved.
MULTIRATE ROBUST SERVOMECHANISM CONTROLLERS OF LINEAR DELAY SYSTEMS USING A HYBRID STRUCTURE
(1994-12-01)
YEN, NZ
;
WU, YC
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電控工程研究所
;
Institute of Electrical and Control Engineering
A multirate robust servomechanism controller design for a linear time delay system is presented. The proposed controller is constructed by using a preparatory continuous internal model followed by a multirate error feedback compensator. An optimal algorithm for choosing the controller parameters is also derived. The algorithm is derived by minimizing a squared deviation error performance index, and the practical optimal solution can simply be solved from a discrete-time algebraic Riccati equation. A distinctive feature of the algorithm is that an optimal pulse compensation is also employed to improve the transient characteristics. Such a pulse compensation tends to eliminate the undesired influence arising from the initial deviation from the ultimate steady-state. In particular, if the initial deviation from the ultimate steady-state is known, then the optimal pulse compensation can drive the system into the steady-state in a time no larger than the input delay time plus the sampling period.
SELECTIVE EPITAXIAL-GROWTH OF GAINP BY LP-MOCVD USING ETHYLDIMETHYLINDIUM, TRIMETHYLINDIUM, TRIMETHYLGALLIUM AND TRIETHYLGALLIUM AS GROUP-III SOURCES
(1994-12-01)
CHAN, SH
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SZE, SM
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CHANG, CY
;
LEE, WI
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電子物理學系
The present experiments demonstrate the epitaxial growth (EG) and selective epitaxial growth (SEG) of GaInP by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) using ethyldimethylindium (EDMI), trimethylindium (TMI), trimethylgallium (TMG) and triethylgallium (TEG) as group III sources. In epitaxial growth of GaInP, the Ga incorporation efficiency using TEG+EDMI is found to be lower than those using other combinations. Completely selective epitaxy using TEGa + EDMIn can be achieved at a growth temperature of 675-degrees-C and at a growth pressure of 40 Torr, while other combinations (TEG + TMI, TMG + TMI, and TMG + EDMI) can achieve SEG of GaInP at 650-degrees-C. High resolution double-crystal X-ray measurements are used to investigate the compositional variation in the selectively epitaxial-grown area.
THE LINEAR 2-ARBORICITY OF COMPLETE BIPARTITE GRAPHS
(1994-12-01)
FU, HL
;
HUANG, KC
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應用數學系
;
Department of Applied Mathematics
A forest in which every component is path is called a path forest. A family of path forests whose edge sets form a partition of the edge set of a graph G is called a path decomposition of a graph G. The minimum number of path forests in a path decomposition of a graph G is the linear arboricity of G and denoted by l(G). If we restrict the number of edges in each path to be at most k then we obtain a special decomposition. The minimum number of path forests in this type of decomposition is called the linear k-arboricity and denoted by la(k)(G). In this paper we concentrate on the special type of path decomposition and we obtain the answers for la2(G) when G is K(n,n). We note here that if we restrict the size to be one, the number la1(G) is just the chromatic index of G.
TEXTURE CLASSIFICATION METHOD USING MULTIPLE SPACE-FILLING CURVES
(1994-12-01)
LEE, JH
;
HSUEH, YC
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資訊工程學系
;
Department of Computer Science
Texture analysis by using the Peano curve does not provide sufficient discriminatory power to classify natural textures. An improved method by simultaneously using several space filling curves to the texture analysis and classification is proposed.
PATH PLANNING IN THE PRESENCE OF OBSTACLES BASED TASK REQUIREMENTS
(1994-12-01)
WU, TH
;
YOUNG, KY
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電控工程研究所
;
Institute of Electrical and Control Engineering
We propose a novel and efficient scheme for planning a kinematically feasible path in the presence of obstacles according to task requirements. By employing geometrical analysis, we derive expressions to describe the relationship between the planned path, kinematic constraints, and obstacles in the robot workspace. The freedom available according to task requirements is then utilized to modify the infeasible portions of the planned path. We use a 6R (revolute) wrist-partitioned type of robot manipulator and a spherical obstacle as a case study to demonstrate the proposed scheme. We then extend our results to general wrist-partitioned types of robot manipulators and arbitrarily-shaped or multiple obstacles. (C) 1994 John Wiley & Sons, Inc.
HIGH-SPEED MEDIAN FILTER DESIGNS USING SHIFTABLE CONTENT-ADDRESSABLE MEMORY
(1994-12-01)
LEE, CY
;
HSIEH, PW
;
TSAI, JM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a very efficient VLSI architecture for real-time median filtering as requested in many image/video applications, The median is obtained by first sorting input sequences and then selecting identified order according to the number of inputs, To reach the goal of high-speed data sorting, an optimized delete-and-insert algorithm is derived and then mapped onto shiftable content-addressable memory architecture, The complete design can be decomposed into a set of processor elements, where each processor element consists of two basic cells- sort-cell and compare-cell, Thus the design becomes very regular, More specifically any specified order can be obtained within one cycle and a high-speed clock rate can be achieved, A proto-type chip for 64 samples based on this architecture has been implemented and tested, Results show that a clock rate up to 50 MHz can be achieved using a 1.2 mu m CMOS double metal technology.