Browsing by Issue Date, starting with "1999-07-20"

Now showing 1 - 20 of 80441

Mixing macro and micro flowtime estimation model: wafer fab example
(1999-07-20)
Tseng, TY
;
Ho, TF
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Accurately predicting the order flowtime for a wafer fab is a critical task. Previous investigations involving flowtime estimation of the regression approach have extensively applied the macro flowtime estimation concept. The 'macro' flowtime estimation concept constructs only one aggregate model to estimate the flowtime as a whole. In contrast, the 'micro' flowtime estimation approach constructs an individual regression model for each stage of operation to estimate its individual flowtime. The cumulative order estimated flowtime is then the sum of the individual estimated operation flowtime. Each approach has its own merits and limitations. Therefore, in this study we examine the feasibility of mixing the macro and micro flowtime estimation models. Comparing the proposed model with a variety of macro and micro models reveals that the mixed macro and micro flowtime estimation model can achieve a balance between flowtime estimation error and model complexity.
Ultrashort pulse generation from mode-locked erbium-doped fibre ring lasers
(1999-07-20)
Chang, CW
;
Chi, S
;
光電工程學系
;
Department of Photonics
A theoretical model of a passively mode-locked erbium-doped fibre ring laser using nonlinear polarization rotation is developed. Numerical simulations are used to study mode-locking and pulse dynamics in a typical ring configuration. The simulations show that stable operation can exist in both isotropic and birefringent fibres, and stable pulses with a FWHM as short as 45 fs can be generated. It is found that there is an optimal regime of ellipticity such that the stable mode-locking can be obtained. In addition, the condition for high birefringence approximation is also found.
Scanning leaky-wave antenna integrated with self-oscillating doubler
(1999-07-20)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
A new method which can enhance the scanning angle and elevate the operating frequency for active scanning leaky-wave antennas is proposed in this paper. We know that the characteristics and performance of scanning leaky-wave antennas are strongly dependent on the variation of the operating frequency within the leaky-mode region. The self-oscillating doubler without external oscillator sources provides double-frequency variation at the second-harmonic frequency instead of one-frequency variation at the fundamental frequency. Therefore, the antenna scanning range can be enhanced and the operating frequency can be elevated. The measured scanning angle of this antenna is 13 degrees which agrees well with the predicted 13.7 degrees and the data show that the frequency-scanning ability of the leaky-wave antenna using a self-oscillating doubler increases as predicted. This self-oscillating doubler design is very simple, and it not only can improve the scanning capability of the active leaky-wave antenna, but it is also very suitable for millimeter-wave active antenna design. (C) 1999 John Wiley & Sons, Inc.
Characteristics of SiC-based thin-film LED fabricated using plasma-enhanced CVD system with stainless steel mesh
(1999-07-22)
Chen, YA
;
Hsu, ML
;
Laih, LH
;
Hong, JW
;
Chang, CY
A conventional plasma-enhanced chemical vapour deposition (PECVD) system with a stainless steel mesh attached to a cathode was used to fabricate an SiC-based thin-mm light-emitting diode (TFLED) at a low temperature (similar to 180 degrees C). The obtained TFLED had a brightness (B) of 1060cd/m(2) at an injection current density (J) of 600mA/cm(2) and a threshold voltage (V-th) of 12.6V, which were much better than those of 330cd/m(2) and 18.5V for an amorphous SiC-based TFLED fabricated by the same PECVD system without a stainless steel mesh.
Anisotropic peak effect due to structural phase transition in the vortex lattice
(1999-07-26)
Rosenstein, B
;
Knigavko, A
;
電子物理學系
;
Department of Electrophysics
It is shown that the recently observed new peak effect in YBCO could be explained by the softening of the vortex lattice due to a structural phase transition in the vortex lattice. At this transition square lattice transforms into a distorted hexagonal one. While conventional peak effect is associated with the softening of shear modes (elastic modulus c(66) vanishes) at melting, in this case the relevant mode is "squash" mode(c(11) + c(22) - 2c(12) vanishes).
Circular chromatic numbers of Mycielski's graphs
(1999-07-28)
Chang, GJ
;
Huang, LL
;
Zhu, XD
;
應用數學系
;
Department of Applied Mathematics
In a search for triangle-free graphs with arbitrarily large chromatic numbers, Mycielski developed a graph transformation that transforms a graph G into a new graph mu(G), we now call the Mycielskian of G, which has the same clique number as G and whose chromatic number equals chi(G) + 1. Let mu(n)(G) = mu(mu(n-1)(G)) for n greater than or equal to 2. This paper investigates the circular chromatic numbers of Mycielski's graphs. In particular, the following results are proved in this paper: (1) for any graph G of chromatic number n, chi(c)(mu(n-1)(G)) less than or equal to chi(mu(n-1)(G)) - 1/2; (2) if a graph G satisfies chi(c)(G) less than or equal to chi(G) - 1/d with d = 2 or 3, then chi(c)(mu(2)(G)) less than or equal to chi(mu(2)(G)) - 1/d; (3) for any graph G of chromatic number 3, chi(c)(mu(G)) = chi(mu(G)) = 4; (4) chi(c)(mu(K-n)) = chi(mu(K-n)) = n + 1 for n greater than or equal to 3 and chi(c)(mu(2)(K-n)) = chi(mu(2)(K-n)) = n + 2 for n greater than or equal to 4. (C) 1999 Elsevier Science B.V. All rights reserved.
把孩子的笑聲加點兒蜜醃起來
(1999-07-31)
管管
Quantum transport in a double-barrier structure in the presence of a finite-range time-modulated potential
(1999-08-01)
Chu, CS
;
Liang, HC
;
電子物理學系
;
Department of Electrophysics
We have studied the quantum transport phenomena in a double-barrier structure acted upon by a finite-range time-modulated potential. Inter-side-band mhw transitions are made possible by the finiteness in the range of the oscillating field. For the case when the barrier width is small, such that the resonance state in between the barriers is too broadened, the de conductance G exhibits peaks or dip structures when the chemical potential mu is at mhw above the band bottom. For the case when the barrier width is large, such that the resonance state in between the barriers is well defined, the above feature is masked by resonant tunneling processes when mu is at energies mhw away from the resonant energy E-b. In both cases, the dips or peaks in G are due to the temporary trapping of the transmitting electrons by the quasi-bound states. Furthermore, for the latter case, we also obtain the quenching of the resonant transmission found by Wagner, but with a small quantitative modification. Our calculation is nonperturbative which is valid for arbitrary potential strength and frequency. The form of the time-modulated potential is expected to be realized in a gate-induced potential configuration.
Temperature control with a neural fuzzy inference network
(1999-08-01)
Lin, CT
;
Juang, CF
;
Li, CP
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Although multilayered backpropagation neural networks (BPNN's) have demonstrated high potential in the nonconventional branch of adaptive control, their long training time usually discourages their applications in industry. Moreover, when they are trained on line to adapt to plant variations, the over-tuned phenomenon usually occurs. To overcome the weakness of the BPNN, in this paper we propose a neural fuzzy inference network (NFIN) suitable for adaptive control of practical plant systems in general and for adaptive temperature control of a water bath system in particular. The NFIN is inherently a modified Takagi-Sugeno-Kang (TSK)-type fuzzy rule-based model possessing a neural network's learning ability. In contrast to the general adaptive neural fuzzy networks, where the rules should be decided in advance before parameter learning is performed, there are no rules initially in the NFIN. The rules in the NFIN are created and adapted as on-line learning proceeds via simultaneous structure and parameter identification. The NFIN has been applied to a practical water bath temperature-control system. As compared to the BPNN under the same training procedure, the simulated results show that not only can the NFIN greatly reduce the training time and avoid the over-tuned phenomenon, but the NFIN also has perfect regulation ability. The performance of the NFIN is also compared to that of the traditional PID controller and; fuzzy logic controller (FLC) on the water bath temperature-control system. The three control schemes are compared through experimental studies with respect to set-points regulation, ramp-points tracking, and the influence of unknown impulse noise and large parameter variation in the temperature-control system. It is found that the proposed NFIN control scheme has the best control performance of the three control schemes.
Determination of stability constants of metal complexes by capillary electrophoresis
(1999-08-01)
Chang, CE
;
Chen, CY
;
Chen, HY
;
生物科技學系
;
Department of Biological Science and Technology
The stability constants of several divalent first row transition and trivalent lanthanide metal complexes were determined by capillary electrophoresis (CE) methods. Four different approaches, i.e. direct formation, ligand exchange, metal exchange and metal-ligand double exchange were developed. To verify if these CE methods are indeed applicable, the stability constant of CuHEDTA was re-determined to be 17.47 +/- 0.20 (consistent with the published 17.50) using the CuEDTA and ZnHEDTA metal-ligand double exchange approach. The stability constants of lanthanide (Ce3+ and Eu3+) and transition metal (Ni2+ and Zn2+) complexes of an aminopolycarboxylate ligand, DO2A (1,7-dicarboxymethyl-1,4,7, 10-tetraazacyclododecane) were measured under the direct complex formation condition. The stability constant of the NiDO2A complex was determined by the ligand exchange method using 1,4,8,11-tetraazaundecane (2,3,2-tet) as the competing ligand. The stability constant of CuDO2A complex was determined by the metal exchange method using Zn2+ ion as the competing metal ion, and complex formation competitions of Ni2+ and Cu2+ between DO2A and 2,3,2-tet were studied by the metal-ligand double exchange method. Effects of experimental conditions and the advantages and limitations of these CE methods are discussed.
【陽明人在四方】洪老師-我的另一半
(國立陽明大學牙醫校友會, 1999-08)
陳彥廷
【陽明人在四方】英倫紀行
(國立陽明大學牙醫校友會, 1999-08)
孔憲蘭
New distributed arithmetic algorithm and its application to IDCT
(1999-08-01)
Chang, TS
;
Chen, C
;
Jen, CW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Distributed arithmetic (DA) has been widely used to implement inner product computations with a fixed input. Conventional ROM-based DA suffers from large ROM requirements. A new DA algorithm is proposed that expands the fixed input instead of the variable input into bit level as in ROM-based DA. Thus the new DA algorithm can take advantage of shared partial sum-of-products and sparse nonzero bits in the fixed input to reduce the number of computations. Unlike ROM-based DA that stores the precomputed results the new DA algorithm uses a predefined structure to compute results. When applied to a 1-D eight-point DCT system the new DA algorithm only needs 30% of hardware area and has faster speed as compared with ROM-based DA. To illustrate the efficiency of the proposed algorithm a 2-D IDCT chip was implemented using 0.8 mu m SPDM CMOS technology. The chip with size 4575 x 5525 mu m can deliver a processing rate of 50 Mpixels per second.
Recognition-based handwritten Chinese character segmentation using a probabilistic Viterbi algorithm
(1999-08-01)
Tseng, YH
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
This paper presents a recognition-based character segmentation method for handwritten Chinese characters. Possible non-linear segmentation paths are initially located using a probabilistic Viterbi algorithm. Candidate segmentation paths are determined by verifying overlapping paths, between-character gaps, and adjacent-path distances. A segmentation graph is then constructed using candidate paths to represent nodes and two nodes with appropriate distances are connected by an are. The cost in each are is a function of character recognition distances, squareness of characters and internal gaps in characters. After the shortest path is detected from the segmentation graph, the nodes in the path represent optimal segmentation paths. In addition, 125 text-line images are collected from seven form documents. Cumulatively, these text-lines contain 1132 handwritten Chinese characters. The average segmentation rate in our experiments is 95.58%. Moreover, the probabilistic Viterbi algorithm is modified slightly to extract text-lines from document pages by obtaining non-linear paths while gaps between text-lines are not obvious. This algorithm can also be modified to segment characters from printed text-line images by adjusting parameters used to represent costs of arcs in the segmentation graph. (C) 1999 Elsevier Science B.V. All rights reserved.
【陽明人在四方】選擇所愛，愛所選擇
(國立陽明大學牙醫校友會, 1999-08)
楊慧瑛
QoS routing in ad hoc wireless networks
(1999-08-01)
Lin, CHR
;
Liu, JS
;
資訊工程學系
;
Department of Computer Science
The emergence of nomadic applications have recently generated much interest in wireless network infrastructures that support real-time communications. In this paper, we propose a bandwidth routing protocol for quality-of-ser,ice (QoS) support in a multihop mobile network. The QoS routing feature is important for a mobile network to interconnect wired networks with QoS support (e.g., ATM, Internet, etc.). The QoS routing protocol can also work in a stand-alone multihop mobile network for real-time applications. Our QoS routing protocol contains end-to-end bandwidth calculation and bandwidth allocation. Under such a routing protocol, the source (or the ATM gateway) is informed of the bandwidth and QoS available to any destination in the mobile network. This knowledge enables the establishment of QoS connections within the mobile network and the efficient support of real-time applications. In addition, it enables more efficient call admission control. In the case of ATM interconnection, the bandwidth information can be used to carry out intelligent handoff between ATM gateways and/or to extend the ATM virtual circuit (VC) service to the mobile network with possible renegotiation of QoS parameters at the gateway. We examine the system performance in various QoS traffic hows and mobility environments via simulation. Simulation results suggest distinct performance advantages of our protocol that calculates the bandwidth information, It is particularly useful in call admission control, Furthermore, "standby" routing enhances the performance in the mobile environment. Simulation experiments show this improvement.
A novel lightly doped drain polysilicon thin-film transistor with oxide sidewall spacer formed by one-step selective liquid phase deposition
(1999-08-01)
Shih, PS
;
Chang, CY
;
Chang, TC
;
Huang, TY
;
Peng, DZ
We have proposed and successfully demonstrated a novel process for fabricating lightly doped drain (LDD) polycrystalline silicon thin-film transistors (TFT's), The oxide sidewall spacer in the new process is formed by a simple one-step selective liquid phase deposition (LPD) oxide performed at 23 degrees C, Devices fabricated with the new process exhibit a lower leakage current and a better ON/OFF current ratio than non-LDD control devices. Since the apparatus used for LPD oxide deposition is simple and inexpensive, the new process appears to be quite promising for future high-performance poly-Si TFT fabrication.
An all-digital phase-locked loop (ADPLL)-based clock recovery circuit
(1999-08-01)
Hsu, TY
;
Shieh, BJ
;
Lee, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new algorithm for all-digital phase-locked loops (ADPLL) with fast acquisition and large pulling range is presented in this paper. Based on the proposed algorithm, portable cell-based implementations for clock recovery with functions of a frequency synthesizer and on-chip clock generator are completed by standard cell, These modules have been designed and verified on a 0.6-mu m CMOS process. Test results are summarized as follows: 1) the proposed ADPLL can satisfy full locked bandwidth and fast acquisition within one data transition; 2) the on-chip clack generator can generate any target clock rate f(clock); and 3) the function of nonreturn-to-zero clock recovery has a maximum f(clock)/4 recovering capability vith a locking range of (tau(input) + tau(input)/2), where tau(input) is the input period.
Interfacial reactions of Co/Si0.76Ge0.24 and Co(Si0.76Ge0.24)/Si0.76Ge0.24 by pulsed KrF laser annealing
(1999-08-01)
Luo, JS
;
Hang, YL
;
Lin, WT
;
Chang, CY
;
Shih, PS
Interfacial reactions of Co/Si0.76Ge0.24 and Co(Si0.76Ge0.24)/Si0.76Ge0.24 by pulsed KrF laser annealing as a function of energy density and pulse number were studied. For the Co/Si0.76Ge0.24 samples annealed at an energy density of 0.2-0.6 J/cm(2), three germanosilicide layers, i.e., amorphous structure and/or nanocrystal, Co(Si1-xGex), and Co(Si1-xGex)(2), were successively formed along the film-depth direction. At 0.3 J/cm(2) Ge segregated to the underlying Si0.76Ge0.24 film, inducing strain relaxation in the residual Si0.76Ge0.24 film. At 0.8 J/cm(2) the reacted region was mostly transformed to a single layer of Co(Si1-xGex)(2), whereas Ge further diffused to the Si substrate. At 1.0 J/cm2, constitutional supercooling appeared. Even the Co(Si0.76Ge0.24) film used as the starting material for laser annealing could not prevent the occurrence of constitutional supercooling at energy densities >1.6 J/cm2. The energy densities at which Co(Si1-xGex) transformation to Co(Si1-xGex)(2), Ge segregation to the underlying Si, and constitutional supercooling occurred were higher for the Co(Si0.76Ge0.24)/Si0.76Ge0.24 system than for the Co/Si0.76Ge0.24 system. Higher energy density and/or pulse number enhanced the growth of Co(Si,,Ge,), film. In the present study, the Co/Si0.76Ge0.24 samples subjected to annealing at 0.2 J/cm(2) for 20 pulses produced a smooth Co(Si,,,Ge,,,), film without inducing Ge segregation out of the germanosilicide and strain relaxation in the unreacted Si0.76Ge0.24 film.
【陽明校園】陽明的學生事務處
(國立陽明大學牙醫校友會, 1999-08)
楊世芳