Browsing by Issue Date, starting with "1999-08"

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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
A dopant-related defect in Te-doped AlInP
(1999-08-01)
Wu, YR
;
Sung, WJ
;
Wen, TC
;
Lee, SC
;
Lee, WI
A deep level in Te-doped Al0.5In0.5P, grown by metal organic chemical vapor deposition, has been studied by deep level transient spectroscopy. The thermal activation energy was 0.24 eV, and the trap concentration was related to Te-dopant concentration. The deep level concentration strongly increased with elevating Te-dopant concentration. Meanwhile, the trap distribution profile also presented the same distribution behavior as the Te concentration profile. Therefore, the deep level in Te-doped AlInP is verified to be a dopant-related defect.
Global motion parameter extraction and deformable block motion estimation
(1999-08-01)
Su, CH
;
Hang, HM
;
Lin, DW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A global motion parameter estimation method is proposed. The method can be used to segment an image sequence into regions of different moving objects. For any tao pixels belonging to the same moving object, their associated global motion components have a fixed relationship from the projection geometry of camera imaging. Therefore, by examining the measured motion vectors we are able to group pixels into objects and, at the same time, identify some global motion information. In the presence of camera zoom, the object shape is distorted and conventional translational motion estimation may not yield accurate motion modeling. A deformable block motion estimation scheme is thus proposed to estimate the local motion of an object in this situation. Some simulation results are reported. For an artificially generated sequence containing only zoom activity, we find that the maximum estimation error in the zoom factor is about 2.8%. Rather good moving object segmentation results are obtained using the proposed object local motion estimation method after zoom extraction. The deformable block motion compensation is also Seen to outperform conventional translational block motion compensation for video material containing zoom activity.
Quadratic temperature dependence of the electron-phonon scattering rate in disordered metals
(1999-08-01)
Hsu, SY
;
Sheng, PJ
;
Lin, JJ
;
電子物理學系
;
物理研究所
We have measured the electron-phonon scattering rates 1/tau(ep) from a weak-localization study of a series of high-resistivity tin-doped Ti73Al27 alloys. The resistivities of these alloys are essentially the same and are so high that the electron elastic mean free path I approaches the interatomic spacing, resulting in a very small value of q(ph) l approximate to 0.0056 T (q(ph) is the wave number of the thermal phonons, and T is the temperature). Based on as many as about 60 magnetoresistivity measurements between 2 and 22 K, we are able to determine the dependence of 1/tau(ep) on T to within a great degree of accuracy and find that 1/tau(ep) varies essentially with T-2 in the dirty limit (q(ph) l much less than 1). This observation is not understood in terms of the current theoretical concept of electron-phonon interaction in disordered metals. [S0163-1829(99)05030-4].
【陽明校園】牙醫科學研究所齒顎矯正組概況
(國立陽明大學牙醫校友會, 1999-08)
胡兆仁
High-power diode-pumped Q-switched intracavity frequency-doubled Nd : YVO4 laser with a sandwich-type resonator
(1999-08-01)
Chen, YF
;
電子物理學系
;
Department of Electrophysics
A compact and efficient diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:YVO4/KTP green laser is demonstrated. With 0.5-at. % Nd:YVO4, greater than 4.6 W of 532-nm average power at a repetition rate of 50 kHz was generated with 17-W pump power, corresponding to a conversion efficiency of 27%. At 10-30 kHz the pulse width is shorter than 10 ns, and the peak power is higher than 13 kW. (C) 1999 Optical Society of America.
Copper chemical vapor deposition films deposited from Cu(1,1,1,5,5,5-hexafluoroacetylacetonate) vinyltrimethylsilane
(1999-08-01)
Lin, PJ
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Copper chemical vapor deposition (Cu CVD) from Cu(hfac)vinyltrimethylsilane was studied using a low pressure chemical vapor deposition (LPCVD) system of a cold-wall vertical reactor. It was found that the resistivity of the chemical vapor deposited Cu films,was dependent on the film's microstructure and impurity content, which in turn. were dependent on the deposition conditions. Using H-2 as the carrier gas, we were able to deposit Cu films of low impurity content at deposition rates as high as 150 Angstrom/min. The lowest resistivity Cu films can be deposited at a temperature of 180 degrees C and a pressure of 300 mTorr.
Quadratic optimization method for multilayer neural networks with local error-backpropagation
(1999-08-01)
Liu, CS
;
Tseng, CH
;
機械工程學系
;
Department of Mechanical Engineering
A fast new local error-backpropagation (LBP) algorithm is presented for the training of multilayer neural networks. This algorithm is based on the definition of a new local mean-squared error function. If the local desired outputs have been estimated, the multilayer neural networks can be decomposed into a set of adaptive linear elements (Adaline) that can be trained by quadratic optimization methods. Among a lot of quadratic optimization methods, the conjugate gradient (CG) method is one of the most famous methods that can find the global optimal solution of quadratic problems within finite steps. The iteration number and the computation time are significantly reduced because the stepsize is computed without line-search. Experimental results on the pattern recognition and memorizing of spatiotemporal patterns are provided.