Browsing by Issue Date, starting with "2003-07-21"

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A Stop-or-Move Mobility model for PCS networks and its location-tracking strategies
(2003-07-21)
Tseng, YC
;
Chen, LW
;
Yang, MH
;
Wu, JJ
;
資訊工程學系
This paper considers the location-tracking problem in PCS networks. Solutions to this problem in fact highly depend on the mobility patterns of mobile subscribers [ACM DIAL-M (1999) 72]. In the literature, many works have assumed a simple random walk model, where mobile subscribers always stay in a roaming state and can move in any direction with equal probability. In this paper, we propose a new Stop-or-Move Mobility (SMM) model, which is characterized by the following features: 'transition between stop and move', 'infrequent transition', 'memory of roaming direction', and 'oblivious in different moves'. Based on this mobility model, a static and an adaptive location-tracking Scheme are developed. The schemes only need to keep very little information for each user. Analyses and simulations are provided, which show that the proposed schemes are quite prospective. (C) 2003 Elsevier Science B,V. All rights reserved.
在溫度分佈量測中達到改善空間解析度的訊號處理方法
(2003-07-21)
祁甡
;
李健仲
;
蔣博文
本發明係提出一種在溫度分佈量測中達到改善空間解析度的訊號處理方法，其係使用短取樣間隔及寬脈波寬度的雷射光源，並結合分解布里淵頻譜的訊號處理方法，將量取光脈波進入感測光纖及過渡重疊區域時之頻譜資料，並利用該等頻譜與加重因子值之關係式求得該脈波真正進入感測光纖中的長度，進而推算出實際溫度變化的位置；最後再利用該位置推導得到一對應於實際感測溫度之布里淵頻譜之頻率漂移值，以藉此得到一感測溫度分佈。本發明不需要短脈波寬度即可達到高空間及高溫度解析度之功效，並同時適用於短或長感測範圍的分佈型溫度量測。
Synthesis of t-butylated diphenylanthracene derivatives as blue host materials for OLED applications
(2003-07-21)
Balaganesan, B
;
Shen, WJ
;
Chen, CH
;
應用化學系
;
資訊工程學系
This paper describes the cost-effective synthesis and the photoluminescence of diphenylanthracene derivatives, which are found to be potential blue host materials for organic light emitting diode (OLED) technology. (C) 2003 Elsevier Ltd. All rights reserved.
Electrooptical properties of GaNAs/GaAs multiple quantum well structures
(2003-07-25)
Lee, JR
;
Chen, YY
;
Lu, CR
;
Lee, WI
;
Lee, SC
The electrooptical properties of the GaNAs/GaAs multiple quantum well structures have been studied using the photoreflectance spectroscopy from 20 K to room temperature. Above the band gap energy of GaAs, Franz-Keldysh oscillations were observed. The period of the Franz-Keldysh oscillations decreased slightly with decreasing temperature, and indicated that the corresponding space charge distribution varied slowly with temperature. The modulated quantum well transition features were observed below the band gap energy of GaAs. A matrix transfer algorithm was used to calculate the quantum well subband energies numerically. The band gap energy and the electron effective mass of the GaNAs/GaAs system were adjusted to obtain the subband energies to best fit the observed quantum well transition energies. (C) 2003 Elsevier Science B.V. All rights reserved.
Correlation between N 1s XPS binding energy and bond distance in metal amido, imido, and nitrido complexes
(2003-07-28)
Wu, JB
;
Lin, YF
;
Wang, JL
;
Chang, PJ
;
Tasi, CP
Synchrotron-based X-ray photoelectron spectroscopy is used to measure N 1s binding energies of several metal amido, imido, and nitrido complexes of group 5 and 6 metals. The N 1s binding energy decreases as the formal M-N bond order increases. A simple correlation between the contraction of the M-N bond and the lowering of binding energy is also observed. This correlation supports a notion that the bonding character of a linear metal-imido linkage resembles that of a metal-nitrido linkage closely.
Bright red-emitting electrophosphorescent device using osmium complex as a triplet emitter
(2003-07-28)
Kim, JH
;
Liu, MS
;
Jen, AKY
;
Carlson, B
;
Dalton, LR
A series of efficient and bright double-layer light-emitting devices have been fabricated using the osmium (Os) complex as the triplet emissive dopant in both a blue-emitting polyfluorene derivative (PF-TPA-OXD) containing hole-transporting triphenylamine (TPA) and electron-transporting oxadiazole (OXD) as side chains and a blend of 2-(4-t-butylphenyl)-5(4-biphenylyl)-1,3,4-oxadizole (PBD) in poly(N-vinylcarbazole) (PVK). Due to a balanced charge injection and transport in PF-TPA-OXD and very efficient energy transfer from this polymer to the Os complex, the resulting device (indium tin oxide/HTL/OsCF3:PF-TPA-OXD/Ca/Ag) reaches a maximum external quantum efficiency of 2.1% with a peak brightness of 2920 cd/m(2). These results are significantly higher than those obtained from the commonly used host, PVK:PBD (0.49% and 1270 cd/m(2)). (C) 2003 American Institute of Physics.
Selective distribution of surface-modified TiO2 nanoparticles in polystyrene-b-poly (methyl methacrylate) diblock copolymer
(2003-07-29)
Weng, CC
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Ordered aggregates of surfactant-modified TiO2 nanoparticles in the selective block of lamellar assemblies of the diblock copolymer PS-b-PMMA have been prepared. The hydrophobic or hydrophilic nature of the tethered surfactant determines the location of TiO2 nanoparticles in the corresponding block, as confirmed by transmission electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The modes of dispersion of TiO2 in the blocks depend on the type of bonding between the surfactant and TiO2. Photoluminescence studies of these nanocomposites demonstrate that the location of TiO2 nanoparticles affect the block copolymer's luminescence at different wavelengths.
Bipanconnectivity and edge-fault-tolerant bipancyclicity of hypercubes
(2003-07-31)
Li, TK
;
Tsai, CH
;
Tan, JJM
;
Hsu, LH
;
資訊工程學系
A bipartite graph is bipancyclic if it contains a cycle of every even length from 4 to I V(G) I inclusive. It has been shown that Q(n) is bipancyclic if and only if n greater than or equal to 2. In this paper, we improve this result by showing that every edge of Q(n) - E' lies on a cycle of every even length from 4 to V(G) inclusive where E' is a subset of E(Q(n)) with E' less than or equal to n - 2. The result is proved to be optimal. To get this result, we also prove that there exists a path of length I joining any two different vertices x and y of Qn when h (x, y) less than or equal to l less than or equal to V(G) - 1 and l - h (x, y) is even where It (x, y) is the Hamming distance between x and y. (C) 2003 Elsevier Science B.V. All rights reserved.
Design and implementation of electromagnetic active control actuators
(2003-08-01)
Bai, MR
;
Ou, KY
;
機械工程學系
;
Department of Mechanical Engineering
We present the modeling, parameter identification and design procedure of a linear voice-coil motor. A numerical simulation has been carried out to facilitate system integration. In particular, we use electromechanical analogy and the time-domain identification procedure with the eigensystem realization algorithm to predict the system response. In order to evaluate the performance of the voice-coil motor, we conducted an experimental investigation. Voice-coil motors mounted on a ball bearing housing are used for generating counter forces to cancel the transverse vibrations of a shaft. A controller is designed by using generalized predictive control. Multiple channel active control systems are implemented on the platform of a digital signal processor. Numerical and experimental results indicated that the designed actuators were effective in suppressing the periodic disturbances in rotors.
Magnetoresistance of La0.7Ca0.3MnO3 thin film biepitaxial step junctions
(2003-08-01)
Chen, SF
;
Chang, WJ
;
Liu, SJ
;
Juang, JY
;
Lin, JY
The biepitaxial La0.7Ca0.3MnO3 (LCMO) thin films grown on SrTiO3 substrates using a buffer layer of anatase TiO2 were fabricated. The magnetoresistance (MR) of biepitaxial step junction (BSJ) across the boundary layer of biepitaxial LCMO (0 0 1) and LCMO (I 10) film was investigated. The temperature and field dependence of MR for BSJ are qualitatively similar to those obtained in other type of artificial grain boundaries with a comparable MR ratio at low temperatures. However, the observed linear current-voltage characteristic across BSJ is in sharp contrary to the commonly reported non-ohmic characteristics. The results are consistent with features predicted by the model of spin-dependent transport across a depressed magnetic ordering and metallic-like junction layer. (C) 2003 Elsevier Science B.V. All rights reserved.
Fabrication and optical property of GaSe thin films grown by pulsed laser deposition
(2003-08-01)
Lee, SH
;
Hsu, YK
;
Hsu, HC
;
Chang, CS
;
Hsieh, WF
The highly oriented (001) GaSe film on c-cut sapphire (0001) was successfully fabricated by pulsed laser deposition. As growth temperature decreases from 550degreesC to 375degreesC, the structure of films changes from cubic zinc-blende Ga2Se3 phase to GaSe phase. The growth temperature of the critical transition from Ga2Se3 phase to GaSe phase is around 500degreesC . From atomic force microscope (AFM) results, it is observed that the growth process of GaSe film is in the manner of layer plus island growth. Besides, the optimal growth conditions of as-grown GaSe film were obtained at a substrate temperature of 400degreesC and laser energy density of 11.7J/cm(2). When the thickness of films goes beyond 800 Angstrom, the stress will be released and the thickness of 1200 Angstrom results in an optimal GaSe film. Furthermore, the indirect bound exciton emission and the recombination via impurity levels or structural defects were observed from low-temperature photoluminescence measurement.
An algorithm for calculating the lower confidence bounds of C-PU and C-PL with application to low-drop-out linear regulators (vol 43, pg 495, 2003)
(2003-08-01)
Pearn, WL
;
Shu, MH
;
工業工程與管理學系
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Department of Industrial Engineering and Management
Fabrication and nonlinear optical properties of nanoparticle silver oxide films
(2003-08-01)
Chiu, Y
;
Rambabu, U
;
Hsu, MH
;
Shieh, HPD
;
Chen, CY
We report the fabrication of nanoparticle silver oxide thin films by rf magnetron sputtering and characterization of their nonlinear optical properties. The chemical decomposition and reversibility of AgOx compounds were studied by thermogravimetric analysis, differential scanning calorimetry, and x-ray diffraction. Electron spectroscopy for chemical analysis measurements revealed a 0.5 eV negative binding energy shift from AgO to Ag2O phase. The effect of particle plasmon resonance was confirmed by the absorption band shift with increased Ag2O Particle size. The measured third-order nonlinear susceptibility (chi(3) = 3.4 x 10(-7) esu) and response time (27 ps) of the Ag2O nanoparticles makes it promising for applications in all-optical switching devices and optical data storage systems. (C) 2003 American Institute of Physics.
Using transforming matrices to generate DNA clone grids
(2003-08-01)
Huang, HM
;
Hwang, FK
;
Ma, HF
;
應用數學系
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Department of Applied Mathematics
Ina yeast artificial chromosome library, DNA clones may be stored in n-dimensional grids. Barillot, Lacroix and Cohen proposed to use the grid lines as pools in a pooling design (used in physical mapping). To screen the clones in a given grid, they noted that it is important to take several copies of the grid, but rearrange the clones such that two clones are in the same grid line at most once. For ease of implementation, biologists proposed using transforming matrices to transform one copy into another. We give a construction of a set of transforming matrices which produce a maximum number of such copies whenever q is a prime power. (C) 2003 Elsevier B.V. All rights reserved.
Corner sequence - A P-admissible floorplan representation with a worst case linear-time packing scheme
(2003-08-01)
Lin, JM
;
Chang, YW
;
Lin, SP
;
資訊工程學系
;
電子工程學系及電子研究所
Floorplanning/placement allocates a set of modules into a chip so that no two modules overlap and some specified objective is optimized. To facilitate floorplanning/placement, we need to develop an efficient and effective representation to model the geometric relationship among modules. In this paper, we present a P-admissible representation, called corner sequence (CS), for non-slicing floorplans. CS consists of two tuples that denote the packing sequence of modules and the corners to which the modules are placed. CS is very effective and simple for implementation. Also, it supports incremental update during packing. In particular, it induces a generic worst case linear-time packing scheme that can also be applied to other representations. Experimental results show that CS achieves very promising results for a set of commonly used MCNC benchmark circuits.
Electrical characteristics of low temperature polysilicon TFT with a novel TEOS/oxynitride stack gate dielectric
(2003-08-01)
Chang, KM
;
Yang, WC
;
Tsai, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This investigation is the first to demonstrate a novel tetraethylorthosilicate. (TEOS)/oxynitride stack gate dielectric for low-temperature poly-Si (LTPS) thin film transistors (TFTs), composed, of a plasma-enhanced chemical vapor deposition (PECVD) thick TEOS oxide/ultrathin oxynitride grown by. PECVD N2O-plasma. The stack oxide shows a very high electrical breakdown field of 8.4 MV/cm, which is approximately 3 MV/cm larger than traditional PECVD TEOS oxide. The field effective mobility of stack oxide UPS TFTs is over 4 times than that of traditional TEOS oxide UPS TFTs. these. improvements are attributed to the high quality N2O-plasma grown ultrathin oxynitride forming strong Si drop N bonds, as well as to reduce the trap density in the dxynitride/poly-Si interface.
Simultaneous amplitude modulation and wavelength conversion in an asymmetric-duty-cycle periodically poled lithium niobate
(2003-08-01)
Chen, YH
;
Fan, FC
;
Lin, YY
;
Huang, YC
;
Shy, JT
We report the theory and experiment for an amplitude modulator and wavelength converter based on an electrode-coated asymmetric-duty-cycle periodically poled lithium niobate (PPLN). In a 56%/44% domain-duty-cycle PPLN crystal, we modulated the amplitude of the 532-nm second-harmonic output and measured a normalized half-wave voltage of 1.1 V x d (mum)/I-eff (cm), where d is the separation of the electrodes and I-cff is the effective electrode length defined by the PPLN length multiplying the deviation of the domain-duty-cycle from the 50% value. A modulation depth of 85% was obtained in the linear modulation regime. We also derived a unified theory to describe the half-wave voltage for two types of PPLN-based amplitude modulators. (C) 2003 Elsevier Science B.V. All rights reserved.
A hierarchical decimation lattice based on N-queen with an application for motion estimation
(2003-08-01)
Wang, CN
;
Yang, SW
;
Liu, CM
;
Chiang, TH
;
資訊科學與工程研究所
We present a novel technique, N-queen lattice, to spatially subsample a block of pixels. Although this lattice is pertinent to many applications, we present an application to speed up motion estimation with minimal loss of coding efficiency. The N-queen lattice is constructed to characterize spatial features in all directions. It can be hierarchically organized for motion estimation With variable nonsquare block size. Despite the randomized lattice structure, we demonstrate that it is possible to achieve compact data storage architecture for efficient memory access and simple hardware implementation. Our simulations show that the N-queen lattice is superior to several existing sampling techniques with improvement in speed by about N times and small loss. in peak SNR.
Grain-boundary magnetoresistance of CrO2 films grown on TiO2-buffered LaAlO3 substrates
(2003-08-01)
Liu, SJ
;
Juang, JY
;
Wu, KH
;
Uen, TM
;
Gou, YS
The magnetic and magnetotransport properties of predominantly (110)-oriented CrO2 films grown on TiO2-buffered LaAlO3 substrates were investigated. The atomic force microscopic images revealed that the as-grown CrO2 films are granular. The magnetic measurements indicated that in-plane coercive fields are about 60 Oe and 100 Oe at 300 K and 7 K, respectively. The as-grown films are semiconductive below 75 K; a magnetoresistance with a DeltaR/R-0 ratio of -13% in a magnetic field of 5 T was observed at 5 K, which is absent in high-quality epitaxial films. The coincidence between the coercive field and the peaks of the magnetoresistive loop measured at low temperatures indicates that spin-dependent scattering plays a crucial role in the transport properties.
Revisited reparameterization invariance of HQET
(2003-08-01)
Yeh, TW
;
物理研究所
;
Institute of Physics
The heavy quark effective theory is invariant under reparameterization. The specific form of the reparameterization transformation is not unique; and it is closely related to the effective theory. The theory invariant under Luke and Manohar's reparameterization transformation is derived.