Browsing by Issue Date, starting with "1997-09-07"

Now showing 1 - 20 of 83428

Recent development of electro-optic polymers for device applications.
(1997-09-07)
Jen, AKY
;
Marder, SR
;
Shu, CF
;
應用化學系
;
Department of Applied Chemistry
Kinetics of the CH3S+O-3 reaction.
(1997-09-07)
Wang, NS
;
Chew, EP
;
Lin, JT
;
Lee, YY
;
Lee, YP
Kinetics of the CH3S+O-3 reaction.
(1997-09-07)
Wang, NS
;
Chew, EP
;
Lin, JT
;
Lee, YY
;
Lee, YP
Studies of stereocontrol in cyclization of hexacarbonyldicobalt-stabilized propargyl cations.
(1997-09-07)
Ho, TL
;
Chang, MH
;
應用化學系
;
Department of Applied Chemistry
Studies of stereocontrol in cyclization of hexacarbonyldicobalt-stabilized propargyl cations.
(1997-09-07)
Ho, TL
;
Chang, MH
;
應用化學系
;
Department of Applied Chemistry
Preparation and epoxy curing of novel dicyclopentadiene-derived Mannich amines
(1997-09-07)
Lin, JJ
;
Lin, SF
;
Chang, FC
;
Tseng, FP
;
應用化學系
Preparation and epoxy curing of novel dicyclopentadiene-derived Mannich amines
(1997-09-07)
Lin, JJ
;
Lin, SF
;
Chang, FC
;
Tseng, FP
;
應用化學系
Negative differential resistance in InGaAs/AlAsSb/InGaAs single-barrier heterostructure
(1997-09-08)
Chen, WK
;
Cheng, RH
;
Ou, J
;
交大名義發表
;
電子物理學系
We have observed negative differential resistance in InP lattice-matched InGaAs/AlAsSb/InGaAs single-barrier tunneling heterostructure. With a 10-nm-thick barrier, the diode exhibits a peak-to-valley current ratio of 4.2 (1.2) and peak current density of 54 (158) A/cm(2) at 100 K(300 K). (C) 1997 American Institute of Physics.
Neural-network-based call admission control in ATM networks with heterogeneous arrivals
(1997-09-08)
Hah, JM
;
Tien, PL
;
Yuang, MC
;
交大名義發表
;
資訊工程學系
Call Admission Control (CAC) has been accepted as a potential solution for supporting diverse, heterogeneous traffic sources demanding different Quality of Services (QOSs) in ATM networks. Also, CAC is required to consume a minimum of time and space to make call acceptance decisions. In this paper, we present an efficient neutral-network-based CAC (NNCAC) mechanism for ATM networks with heterogeneous arrivals. All heterogeneous traffic calls are initially categorized into various classes. Based an the number of calls in each class, NNCAC efficiently and accurately estimates the cell delay and cell loss ratio of each class in real time by means of a pre-trained neutral network. According to our decent study which exhibits the superiority of the employment of analysis-based training data over simulation-based data, we particularly construct the training data from a heterogeneous-arrival dual-class queueing model M-[N1] + I-[N2]/D/1/K, where M and I represent the Bernoulli and interrupted Bernoulli processes, and N-1 and N-2 represent the corresponding numbers of calls, respectively. Analytic results of the queueing model are confirmed by simulation results. Finally, we demonstrate the profound agreement of our neural-network-based estimated results with analytic results, justifying the viability of our NNCAC mechanism. (C) 1997 Elsevier Science B.V.
Single-layer organic electroluminescent devices by vapor deposition polymerization
(1997-09-08)
Wen, WK
;
Jou, JH
;
Chiou, JF
;
Chang, WP
;
Whang, WT
A novel method is presented herein regarding the preparation of a single-layer organic electroluminescent (EL) polymer thin film device. The device was made by simultaneously co-depositing two polymer thin film forming monomers, a hole-transporting molecule triphenyldiamine derivative (TPD) and an EL active molecule 1,1 4, 4-tetraphenyl-1,3-butadiene (TPB) on an indium-tin-oxide (ITO) glass substrate. The device structure was composed of the ITO glass, the TPD, and TPB co-doped polymer thin film, and a thermally evaporated aluminum electrode. Carrier injection from the two electrodes was significantly observed and the blue light in EL spectra, with an emission maximum at 435 nm, was triggered at a driving voltage of 17 V. (C) 1997 American Institute of Physics.
Deviations from quantized Hall conductivity and current density distribution in finite 2DEG samples
(1997-09-10)
Bartos, I
;
Rosenstein, B
;
電子物理學系
;
Department of Electrophysics
Simple expressions for local and total Hall conductivities in finite two dimensional electron systems under magnetic field are obtained from the Kubo formula. The deviations of the Hall conductivity from integer values are always negative and their magnitude is inversely proportional to the effective width of the sample and proportional to the slope of the Landau branch dispersion relation at the Fermi level, Eq. (22). We also calculate the local conductivity in finite samples. The conductivity density is constant in the bulk and sums up to an integer value. Its spatial distribution is terminated in the bulk in a universal manner. Illustrations for simple models of the confinement barrier, as well as relation to recent experimental data for quantum wires are given.
Deviations from quantized Hall conductivity and current density distribution in finite 2DEG samples
(1997-09-10)
Bartos, I
;
Rosenstein, B
;
電子物理學系
;
Department of Electrophysics
Simple expressions for local and total Hall conductivities in finite two dimensional electron systems under magnetic field are obtained from the Kubo formula. The deviations of the Hall conductivity from integer values are always negative and their magnitude is inversely proportional to the effective width of the sample and proportional to the slope of the Landau branch dispersion relation at the Fermi level, Eq. (22). We also calculate the local conductivity in finite samples. The conductivity density is constant in the bulk and sums up to an integer value. Its spatial distribution is terminated in the bulk in a universal manner. Illustrations for simple models of the confinement barrier, as well as relation to recent experimental data for quantum wires are given.
Yellow luminescence in n-type GaN epitaxial films
(1997-09-15)
Chen, HM
;
Chen, YF
;
Lee, MC
;
Feng, MS
;
材料科學與工程學系
Photoluminescence, resonant Raman scattering, and photoconductivity measurements have been employed to study the yellow; emission in undoped n-type and a set of Se-doped GaN epitaxial films. It is best described by a transition from the conduction-band edge to a deep acceptor. Unlike the donors and accepters used in most previous studies that substitute Ga sires, Se atoms can replace N sites. With this unique fact, we identify that the origin of the yellow emission involves the nitrogen antisite. In addition, it is found that persistent photoconductivity can be observed after the yellow; band excitation, We further suggest that the nitrogen antisite exhibits a metastable behavior similar to the arsenic antisite in GaAs.
Precision side-polished fibers with a long interaction length
(1997-09-15)
Liaw, SK
;
Chiu, JY
;
Tseng, SM
;
光電工程學系
;
Department of Photonics
We succeeded in fabricating precision side-polished fibers embedded in silicon V-grooves and then polished six fibers using a home-made polisher. The control of the polishing depth of the side-polished fibers was as accurate as +/-0.25 mu m. Another merit of our polished samples was their negligible losses even though the effective interaction lengths were long. Experimental calibrations of our samples agreed with theoretical results.
Precision side-polished fibers with a long interaction length
(1997-09-15)
Liaw, SK
;
Chiu, JY
;
Tseng, SM
;
光電工程研究所
;
Institute of EO Enginerring
We succeeded in fabricating precision side-polished fibers embedded in silicon V-grooves and then polished six fibers using a home-made polisher. The control of the polishing depth of the side-polished fibers was as accurate as +/-0.25 mu m. Another merit of our polished samples was their negligible losses even though the effective interaction lengths were long. Experimental calibrations of our samples agreed with theoretical results.
Electroreflectance of surface-intrinsic- n(+)-type doped GaAs
(1997-09-15)
Wang, DP
;
Huang, KM
;
Shen, TL
;
Huang, KF
;
Huang, TC
The electroreflectance spectra of surface-intrinsic-n(+)-type-doped GaAs were measured at various bias voltages (V-bias). Results revealed many Franz-Keldysh oscillations (FKOs) above the band-gap energy, which have been attributed to a uniform electric field (F) in the undoped layer below the surface. However, there has been no other evidence for the uniformity of F in the undoped layer. Since it is known that F can be deduced from the periods of the FKOs, the relations between F and V-bias can, thereby, be obtained. The nearly linear relation, thus found, confirms the existence of a nearly uniform field in the undoped layer. From the plot of F against V-bias,the Values of the thickness of the undoped layer and the barrier height can also be evaluated. (C) 1997 American Institute of Physics.
Electroreflectance of surface-intrinsic- n(+)-type doped GaAs
(1997-09-15)
Wang, DP
;
Huang, KM
;
Shen, TL
;
Huang, KF
;
Huang, TC
The electroreflectance spectra of surface-intrinsic-n(+)-type-doped GaAs were measured at various bias voltages (V-bias). Results revealed many Franz-Keldysh oscillations (FKOs) above the band-gap energy, which have been attributed to a uniform electric field (F) in the undoped layer below the surface. However, there has been no other evidence for the uniformity of F in the undoped layer. Since it is known that F can be deduced from the periods of the FKOs, the relations between F and V-bias can, thereby, be obtained. The nearly linear relation, thus found, confirms the existence of a nearly uniform field in the undoped layer. From the plot of F against V-bias,the Values of the thickness of the undoped layer and the barrier height can also be evaluated. (C) 1997 American Institute of Physics.
Probing flavor changing neutral Higgs couplings at LHC
(1997-09-18)
Hou, WS
;
Lin, GL
;
Ma, CY
;
Yuan, CP
;
電子物理學系
Uniquely heavy with mass at the weak scale, the top quark may have large flavor changing couplings to Higgs bosons that are as yet unexplored. We show that such couplings could be directly probed at the LHC through the parton subprocess c((c) over bar)g --> t((t) over bar)A(0), where the pseudoscalar A(0) subsequently decays into t (c) over bar or (t) over bar c, giving rise to the intriguing final state of like sign top quark pairs. After demanding l(+/-)l(+/-), missing energy and two b-jets, the major background turns out to be q (q) over bar' --> Wt (t) over bar, which can be partially suppressed by jet counting. The signal can then manifest itself in the asymmetry of numbers of l(+)l(+) and l(-)l(-) events. To further improve the signal over background, efficient t vs. (t) over bar tagging methods should be developed. (C) 1997 Elsevier Science B.V.
Probing flavor changing neutral Higgs couplings at LHC
(1997-09-18)
Hou, WS
;
Lin, GL
;
Ma, CY
;
Yuan, CP
;
電子物理學系
Uniquely heavy with mass at the weak scale, the top quark may have large flavor changing couplings to Higgs bosons that are as yet unexplored. We show that such couplings could be directly probed at the LHC through the parton subprocess c((c) over bar)g --> t((t) over bar)A(0), where the pseudoscalar A(0) subsequently decays into t (c) over bar or (t) over bar c, giving rise to the intriguing final state of like sign top quark pairs. After demanding l(+/-)l(+/-), missing energy and two b-jets, the major background turns out to be q (q) over bar' --> Wt (t) over bar, which can be partially suppressed by jet counting. The signal can then manifest itself in the asymmetry of numbers of l(+)l(+) and l(-)l(-) events. To further improve the signal over background, efficient t vs. (t) over bar tagging methods should be developed. (C) 1997 Elsevier Science B.V.
Charge transfer process in Tl2Ba2Ca2Cu3O10 and Tl2Ba2CaCu2O8 thin films probed by polarized X-ray absorption spectroscopy
(1997-09-26)
Chen, JM
;
Liu, RG
;
Liu, RS
;
Lin, HC
;
Uen, TM
We report high-resolution polarized O 1s X-ray absorption spectra of highly c-axis-oriented Tl2Ba2Ca2Cu3O10 (Tl-2223) and Tl2Ba2CaCu2O8 (Tl-2212) superconducting thin films. Near the O Is edge, the low-energy pre-edge peak at 528.3 eV has mainly O 2p(xy) symmetry, while the pre-edge peak at 529.4 eV has predominantly O 2p, character. The spectral weight of the pre-edge peak at 528.3 eV, originating from the CuO2 planes, increases similar to 60% from the Tl-2212 to Tl-2223 thin films. Conversely, the high-energy pre-edge peak at 530.3 eV, originating from the TlO planes, is lower in spectral intensity by similar to 30% in Tl-2223 as compared to the Tl-2212 thin film. The experimental results clearly demonstrate the pictures of the self doping due to the charge transfer from the CuO2 layers to the TlO layers. (C) 1997 Published by Elsevier Science B.V.