Browsing by Issue Date, starting with "2001-01-06"

Now showing 1 - 20 of 76775

A typical vertex of a tree
(2001-01-06)
Wei, PH
;
Weng, CW
;
應用數學系
;
Department of Applied Mathematics
Let T denote a tree with at least three vertices. Observe that T contains a vertex which has at least two neighbors of degree one or two. A class of algorithms on trees related to the observation are discussed and characterized. One of the example is an algorithm to compute the minimum rank m(T) of the symmetric matrices with prescribed graph T, which is easier to process than the algorithm previous found by Nylen [Linear Algebra Appl. 248 (1996) 303-316]. Two interpretations of the number m(T) in terms of some combinatorial properties on trees are given. (C) 2001 Elsevier Science B.V. All rights reserved. MSC: 05C05.
A note on ascending subgraph decompositions of complete multipartite graphs
(2001-01-06)
Fu, HL
;
Hu, WH
;
應用數學系
;
Department of Applied Mathematics
In this note, we prove that the ascending subgraph decomposition conjecture is true for complete multipartite graphs. (C) 2001 Elsevier Science B.V. All rights reserved. MSG: 05C70.
The decay number and the maximum genus of diameter 2 graphs
(2001-01-06)
Fu, HL
;
Tsai, MC
;
Xuong, NH
;
應用數學系
;
Department of Applied Mathematics
Let zeta (G) (resp. xi (G)) be the minimum number of components (resp. odd size components) of a co-tree of a connected graph G. For every 2-connected graph G of diameter 2, it is known that m(G)greater than or equal to 2n(G) - 5 and xi (G)less than or equal to zeta (G)less than or equal to4. These results define three classes of extremal graphs. In this paper, we prove that they are the same, with the exception of loops added to vertices. (C) 2001 Elsevier Science B.V. All rights reserved. MSC: Primary 05C10; Secondary 05C70.
Novel phosphorus-containing dicyclopentadiene-modified phenolic resins for flame-retardancy applications
(2001-01-10)
Hsiue, GH
;
Shiao, SJ
;
Wei, HF
;
Kuo, WJ
;
Sha, YA
2- [4-(2-hydroxyphenyl)tricyclo[5.2.1.0(2,6)]dec-8-yl]phenol (HPTCDP) were prepared from dicyclopentadiene (DCPD) and phenol via Friedel-Crafts alkylation. DCPD-containing phenolic resin (DPR) was also synthesized by incorporating the DCPD-containing monomer HPTCDP with formaldehyde. DPR was further modified by grafting the phosphate group. The phosphorylation was confirmed by a Fourier transform infrared, P-31-NMR spectroscopy, and an element analysis. The phosphorus content in the DPR could be successfully tailored to give values of 3.46 to 7.79 wt % by varying the feeding ratios of the phosphorus group. The thermal stabilities of the phosphorus-containing polymers were identified by differential scanning calorimeter and thermogravimetric analysis. The glass transition temperature values were decreased as the content of phosphorus increased. High char yield 39-47 wt % in thermogravimetric analysis evaluation and limiting oxygen index values of 27 to 34 were found for all the phosphorylated phenolic resins. Such properties make these polymers highly promising for flame-retardant applications. (C) 2000 John Wiley & Sons, Inc.
A novel preparation of polyimide/clay hybrid films with low coefficient of thermal expansion
(2001-01-10)
Gu, AJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A novel polyimide (PI)/clay hybrid nanocomposite, designated as PI (PAAS)/CM, has been developed from the poly(amic acid) salt of triethylamine and organomontmorillonite (CM) using a mixture solution of tetrahydrofuran (THF) and methanol (MeOH). For comparison, two other PI/clay hybrids derived from poly(amic acid) and CM in THF/MeOH solution and N,N'-dimethylacetamide (DMAc) solution, denoted as PI/CM (T/M) and PI/CM (DMAc), respectively, were also prepared. Dispersion of CM in polymer matrix, tensile properties, and thermal expansion properties of the three hybrids were investigated. Results show that PI (PAAS)/CM has the best dispersion of CM in polymer matrix, highest elongation, and lowest coefficient of thermal expansion values in all hybrids presented in this report. In addition, PI/CM (T/M) has better dispersion of CM and lower coefficient of thermal expansion value than PI/CM (DMAc). (C) 2000 John Wiley & Sons, Inc.
A synthetic approach to tacamonine. Access to 3-epitacamonine and 14-epitacamonine
(2001-01-14)
Ho, TL
;
Su, CY
;
應用化學系
;
Department of Applied Chemistry
3-Epitacamonine and 14-epitacamonine have been synthesized starting from the dinitrile 3. The synthetic route was designed on the basis of symmetric considerations which emphasized the establishment of the relative configuration in two of the three stereocenters. (C) 2001 Elsevier Science Ltd. All rights reserved.
Deep level transient spectroscopy characterization of InAs self-assembled quantum dots
(2001-01-15)
Ilchenko, VV
;
Lin, SD
;
Lee, CP
;
Tretyak, OV
;
電子工程學系及電子研究所
Deep level transient spectroscopy (DLTS) was used to obtain the energy level and the capture characteristics of InAs self-assembled quantum dots embedded in GaAs. A specially designed structure was used for the DLTS measurement for enhanced resolution. This structure allows us to detect capacitance relaxation signal from a single layer of quantum dots and to separate this signal from those of the DX centers inside the structure. The DLTS spectra with different filling pulses and different rate windows provide clear information on the energy level and the capture characteristics of the quantum dots. (C) 2001 American Institute of Physics.
A beam-forming technique for leaky-wave antennas
(2001-01-20)
Chen, IY
;
Wang, CJ
;
Liu, SJ
;
Jou, CF
;
傳播研究所
A beam-forming technique for leaky-wave antennas (LWAs) which can switch electronically in three different radiation patterns is developed in this letter. A simple two-terminal feeding microstrip-line LWA works as a radiating element. By varying the phase of the two injection signals from 0 to 180 degrees, the emitting power from the LWA can produce three different radiation modes: the normal mode (one sharp beam), the difference mode (Delta), and the sum mode (Sigma). The antenna displays large-bandwidth characteristics, and can be useful near crossroads for collision avoidance or in the radio location of vehicles. (C) 2001 John Wiley & Sons, Inc.
The shuffle-cubes and their generalization
(2001-01-31)
Li, TK
;
Tan, JJM
;
Hsu, LH
;
Sung, TY
;
資訊工程學系
In this paper, we first present a new variation of hypercubes, denoted by SQ(n) .SQ(n) is obtained from Q(n) by changing some links. Sa, is also an n-regular n-connected graph but of diameter about n/4. Then, we present a generalization of Se,. For any positive integer g, we can construct an n-dimensional generalized shuffle-cube with 2(n) vertices which is n-regular and n-connected. However its diameter can be about n/g if we consider g as a constant. (C) 2001 Elsevier Science B.V. All rights reserved.
Interface induced uphill diffusion of boron: An effective approach for ultrashallow junction
(2001-02-01)
Wang, HCH
;
Wang, CC
;
Chang, CS
;
Wang, TH
;
Griffin, PB
This paper investigates anomalous diffusion behavior for ultra low energy implants in the extension or tip of PMOS devices. Transient enhanced diffusion (TED) is minimal at these low energies, since excess interstitials are very close to the surface, Instead, interface induced uphill diffusion is found, for the first time, to dominate during low temperature thermal cycles. The interface pile-up dynamics can be taken advantage of to produce shallower junctions and improve short channel effect control in PMOS devices, Attempts to minimize TED before spacer deposition by inclusion of extra RTA. anneals are shown to be detrimental to forming boron ultra shallow junctions.
Differential capacitance measurements of relaxation-induced defects in InGaAs/GaAs Schottky diodes
(2001-02-01)
Chen, JF
;
Chen, NC
;
Wang, JS
;
Chen, YF
;
電子物理學系
The use of a differential capacitance technique for characterizing the relaxation-induced defect states in Schottky diodes has been studied, Based on a proposed equivalent circuit including the effect of potential drop across the carrier-depletion layer, a simple equation of capacitance at different voltages and frequencies is derived and compared with experimental data obtained from relaxed In0.2Ga0.8As/GaAs samples, It is shown that the carrier-depletion layer will introduce capacitance dispersion over frequency like traps; from it the device's geometric parameters, the resistance of the carrier-depletion lager and the ionization energy of the deep level that gives rise to this resistance can be obtained. The relation between the low-frequency capacitance and reverse voltage can be well explained by the depletion of the free carriers between the Schottky depletion and the carrier-depletion layer The relaxation-induced traps are believed to be at 0.535 and 0.36 eV, respectively, in the GaAs and In0.2Ga0.8As regions.
Mode control of vertical-cavity surface-emitting lasers by germanium coating
(2001-02-01)
Chiou, SW
;
Lin, G
;
Lee, CP
;
Yang, HP
;
Sung, CP
We have successfully developed a selective surface coating technique to control the modal behavior of the ion-implanted vertical-cavity surface-emitting laser (VCSEL). With selective deposition of a germanium coating by the lift-off process, we could spatially control the threshold gain condition of the VCSEL to support the single transverse mode. The threshold current is 7 mA and single transverse mode operation is maintained up to I mW. The method is simple and nondestructive compared with other techniques.
Obstacle avoidance in person following for vision-based autonomous land vehicle guidance using vehicle location estimation and quadratic pattern classifier
(2001-02-01)
Ku, CH
;
Tsai, WH
;
資訊工程學系
;
Department of Computer Science
An obstacle avoidance method for use in person following for vision-based autonomous land vehicle (ALV) guidance is proposed. This method is based on the use of vehicle location estimation and a quadratic pattern classifier, and aims to guide the ALV to follow a walking person in front by navigating along a derived collision-free path. Before generating the collision-free path, the person's location is obtained from extracted objects in the image by a person detection method. The object closest to a predicted person location is regarded as the followed person and the remaining objects are regarded as obstacles. The collision-free navigation path is designed for ALV guidance in such a way that the ALV not only can keep following the person but also can avoid collision with nearby obstacles. The navigation path results from a quadratic classifier that uses the vehicle and all of the objects in the image as input patterns. A turn angle is then computed to drive the ALV to follow the navigation path. Successful navigation sessions confirm the feasibility of the approach.
High quality interpoly-oxynitride grown by NH3 nitridation and N2O RTA treatment
(2001-02-01)
Pan, TM
;
Lei, TF
;
Yang, WL
;
Cheng, CM
;
Chao, TS
In this letter, a method to grow high quality interpolysilicon-oxynitride (interpoly-oxynitride) film is proposed. Samples, nitridized by NH3 with additional N2O annealing and CVD TEOS deposited on poly-oxynitride (poly-I) with RTA NaO oxidation, show excellent electrical properties in terms of very high electric breakdown field, ion; leakage current, high charge to breakdown, and low electron trapping rate. This novel film is a good candidate for an interpoly dielectric of future high density EEPROM and flash memory devices.
Incorporating error shaping technique into LSF vector quantization
(2001-02-01)
Nein, HW
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an error shaping technique for line spectrum frequency (LSF) vector quantization, The error shaping technique based on the weighted logarithm spectral distortion (WLSD) measure can be used for shaping the spectral distortion distribution of quantization error into any different curve depending on what kind of weighting function is used. However, the high computational complexity of the WLSD measure deters this error shaping technique from practical use. To solve this problem, we approximate the WLSD measure by the quadratically weighted measure or the weighted mean squared error (WMSE) measure and propose an optimal error shaping technique of LSF vector quantization. In this proposed error shaping technique, the optimal WMSE weights (i.e., the optimal weights of LSF parameters) are determined based on the theoretical analysis of the WLSD measure. Three experiments are performed to check the performance of the proposed error shaping technique. One experiment is set up by incorporating human perception into the LSF quantization and another is set up by emphasizing the human-sensitivity frequency band in lower frequency bandwidth 0-3 kHz. In the third experiment, we apply the proposed error shaping technique to the LSF quantization of a CELP coder to test how it affects the overall speech quality in an actual speech coding algorithm.
1.55-mu m and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector
(2001-02-01)
Lee, MK
;
Chu, CH
;
Wang, YH
;
Sze, SM
;
電子工程學系及電子研究所
We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum. The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum, 10-mW laser diode. The corresponding quantum efficiency is 14.4%. (C) 2001 Optical Society of America.
A note on optimal policies for a periodic inventory system with emergency orders
(2001-02-01)
Chiang, C
;
管理科學系
;
Department of Management Science
In this article, we develop a dynamic programming model for a periodic review inventory system in which emergency orders can be placed at the start of each period, while regular orders are placed at the beginning of an order cycle (which consists of a number of periods). We assume that the regular and emergency supply lead times differ by one period. We devise a simple algorithm of computing the optimal policy parameters. Thus, the ordering policy developed is easy to implement.
Discovering anomalies in access modifiers in Java with a formal specification
(2001-02-01)
Yang, W
;
交大名義發表
;
National Chiao Tung University
The Java programming language provides three access modifiers to control the visibility of the members of a class. Though identifying the weaknesses of the access modifiers from the informal semantics stated in the language manual is difficult, this does not mean that the access modifiers provide a sound ground for building secure programs. A rigorous study of the access modifiers with attribute grammars has uncovered several situations that are irregular or counterintuitive. These situations are confusing to programmers and may create weaknesses in Java programs.
Bayesian analysis of a growth curve model with power transformation, random effects and AR(1) dependence
(2001-02-01)
Lee, JC
;
Lien, WH
;
統計學研究所
;
Institute of Statistics
In this paper we devote ourselves to a general growth curve model with power transformation, random effects and AR(1) dependence via a Bayesian approach. Two priors are proposed and both parameter estimation and prediction of future values are considered. Some numerical results with a set of real data are also given.
Behaviors of negative resistances and its influences on VCO design
(2001-02-01)
Kao, YH
;
Wu, TH
;
傳播研究所
;
Institute of Communication Studies
The features of the negative resistance in common source and common gate FET configurations for wideband VCO are studied. They are also explained by the simplified three-capacitor model. A design procedure is then developed. The results are applied to a design of wide band oscillator at the several gigahertz region.