Browsing by Issue Date, starting with "1993-10-01"

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FORCED VIBRATION OF FLEXIBLE BODY SYSTEMS - A DYNAMIC STIFFNESS METHOD
(1993-10-01)
LIU, TS
;
LIN, JC
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
Due to the development of high speed machinery, robots, and aerospace structures, the research of flexible body systems undergoing both gross motion and elastic deformation has seen increasing importance. The finite element method and modal analysis are often used in formulating equations of motion for dynamic analysis of the systems which entail time domain, forced vibration analysis. This study develops a new method based on dynamic stiffness to investigate forced vibration of flexible body systems. In contrast to the conventional finite element method, shape functions and stiffness matrices used in this study are derived from equations of motion for continuum beams. Hence, the resulting shape functions are named as dynamic shape functions. By applying the dynamic shape functions, the mass and stiffness matrices of a beam element are derived. The virtual work principle is employed to formulate equations of motion. Not only the coupling of gross motion and elastic deformation, but also the stiffening effect of axial forces is taken into account. Simulation results of a cantilever beam, a rotating beam, and a slider crank mechanism are compared with the literature to verify the proposed method.
THE DELAY ANALYSIS IN A NOISY GENERAL CUT-THROUGH SWITCHING NETWORK
(1993-10-01)
CHANG, CJ
;
CHIU, JH
;
LIN, SJ
;
電信研究中心
;
Center for Telecommunications Research
The transfer delay of data packet in a noisy n-node tandem network with general cut-through switching is analyzed in this paper. By assuming each node as an M/G/1 and considering error control done only at the store-and-forward node and done at every node, respectively, the transfer delays of a data packet are determined. Both delays are illustrated and compared in numerical examples. Also, proof of the equality of the transfer delays for the two error control strategies in error free network are conducted to help verifying the validity of the analysis.
THE ANALYSIS OF LINEAR ROTOR-BEARING SYSTEMS - A GENERAL TRANSFER-MATRIX METHOD
(1993-10-01)
LEE, AC
;
SHIH, YP
;
KANG, Y
;
交大名義發表
;
機械工程學系
A general transfer matrix method (GTMM) is developed in the present work for analyzing the steady-state responses of rotor-bearing systems with an unbalancing shaft. Specifically, we derived the transfer matrix of shaft segments by considering the state variables of shaft in a continuous system sense to give the most general formulation. The shaft unbalance, axial force, and axial torque are all taken into consideration so that the completeness of transfer matrix method for steady-state analysis of linear rotor-bearing systems is reached. To demonstrate the effectiveness of this approach, a numerical example is presented to estimate the effect of three-dimensional distribution of shaft unbalance on the steady-state responses by GTMM and finite element method (FEM).
SYNTHESIS AND CHARACTERIZATION OF NOVEL FLUORINATED DIPHENYLDIACETYLENIC LIQUID-CRYSTALS
(1993-10-01)
JUANG, TM
;
CHEN, YN
;
LUNG, SH
;
LU, YH
;
HSU, CS
Five series of asymmetric diphenyldiacetylenes containing a single fluorine, two fluorines or a trifluoromethyl group at one end and an alkyl, alkyloxy or alkenyloxy group on the other end, were prepared and characterized. Most of the 4-alkylphenyl-4'-fluorophenyldiacetylenes, 4-alkyloxyphenyl-4'-fluorophenyl-diacetylenes and 4-alkenyloxyphenyl-4'-fluorophenyldiacetylenes obtained exhibit an enantiotropic nematic phase and no smectic phase. However, most of the 4-alkyl-3', 4'-difluorodiphenyldiacetylenes, 4-alkenyloxy-3',4'-difluorodiphenyl-diacetylenes and 4-alkyl-4'-trifluoromethyldiphenyldiacetylenes show no meso-morphic behaviour. The effects of alkyl, alkyloxy, alkenyloxy, fluoro, 3,4-difluoro and trifluoromethyl end groups on the mesomorphic behaviour of the diphenyldiacetylenes prepared are discussed.
OPTIMAL PERIODIC CONTROL IMPLEMENTED AS A GENERALIZED SAMPLED-DATA HOLD OUTPUT-FEEDBACK CONTROL
(1993-10-01)
YEN, NZ
;
WU, YC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this note, a conversion method to convert the analog linear quadratic regulation control to a generalized sampled-data hold output feedback control for a linear periodic system or a linear time-invariant system is presented. It is shown that by using such a conversion, one can implement the optimal periodic control scheme in the presence of incomplete and delayed state measurements.
INVESTIGATION OF SI-SIO2 INTERFACE PROPERTIES FOR BONDED SILICON-ON-INSULATOR
(1993-10-01)
YEH, CF
;
KAO, HW
;
CHANG, BS
;
CHANG, KL
;
交大名義發表
A ROBUST OVER-THE-CELL CHANNEL ROUTER
(1993-10-01)
CHANG, LD
;
HSIAO, PY
;
YAN, JT
;
SHEW, PW
;
資訊工程學系
In this paper, we present an efficient algorithm for over-the-cell routing in the standard cell layout design technology. Two variations are discussed: one aims to minimize the channel density with fewest tracks over the cells while the other aims to minimize the final channel width. Our algorithm can fit both the two-layer and three-layer routing models. With the two-layer model, there is a single routing layer over the cells for intercell connections. While with the three-layer model, there are two disjoint routing layers over the cells for intercell connections. In our approach, we decompose the problem into two phases: (1) over-the-cell routing and (2) conventional channel routing. The over-the-cell routing phase, which is executed iteratively, consists of two steps, routing over the cells and choosing net segments within the channel. For each iteration in the over-the-cell routing phase, our algorithm removes a net or a subnet which intersects the column with highest column density and route it over the cells according to some prioritized criteria. In comparison with the previous researches, our approach achieved the best effectiveness and has used the least CPU-time. On the average, the execution speed of our router is 163 and 4163 times faster than that of [8] and [9], respectively. Besides, our algorithm can produce results comparable to those produced by the WISER algorithm [10].
EVIDENCE OF ZERO POTENTIAL SPIKE ENERGY IN ALGAAS GAAS HETEROSTRUCTURE EMITTER BIPOLAR-TRANSISTORS
(1993-10-01)
CHEN, HR
;
LEE, CP
;
CHANG, CY
;
TSAI, KL
;
TSANG, JS
The potential spike energy at the emitter junction of AlGaAs/GaAs heterostructure emitter bipolar transistors (HEBT) was directly measured for the first time. Experimental data revealed that emitter thickness as thin as 300 angstrom is thick enough to eliminate potential spike without compositional grading. It is found that the band bending in n-GaAs reduces the potential spike and hence very low offset voltage of 70 mV with high current gain of 150 can be obtained.
SLIDING-MODE CONTROLLER-DESIGN FOR SPACECRAFT ATTITUDE TRACKING MANEUVERS
(1993-10-01)
CHEN, YP
;
LO, SC
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
This paper presents a robust sliding-mode control law to deal with the spacecraft attitude tracking problems. Two important natural properties related to the spacecraft model of motion are shown and then by using these properties and the second method of Lyapunov theory, the system stability in the sliding mode can be easily achieved. The success of the sliding-mode controller and the robustness to uncertainties are illustrated by an example of multiaxial attitude tracking maneuvers.
ANALOG STUDY OF BIFURCATION STRUCTURES IN A VANDERPOL OSCILLATOR WITH A NONLINEAR RESTORING FORCE
(1993-10-01)
KAO, YH
;
WANG, CS
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電信工程研究所
;
光電工程研究所
;
Institute of Communications Engineering
The injection locking and chaotic transitions in a Van der Pol oscillator with a nonlinear-restoring-force term were investigated in this article via an electronic circuit. Three types of locking processes were differentiated from each other in light of local and global bifurcations. The influences of the nonlinear restoring force on the bifurcation structure were also discussed.
RAMAN-SCATTERING OF THIN-FILM C-60/C-70 FULLERENES
(1993-10-01)
LO, KL
;
LEE, MC
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交大名義發表
;
電子物理學系
;
National Chiao Tung University
High quality thin film fullerenes of C60, C70, and 50% mixture C60/70 were studied by Raman scattering. We observed not only ten complete (2A(g) + 8H(g)) modes in C60, which are assigned in accordance with the point group of a truncated icosahedron, but also drastically more (38) lines in C70, that is owing to the reduced symmetry. By measuring the 50% mixture sample, we were able to distinguish the features of C60 from that of C70. Most of the C60 modes appear at higher frequencies with respect to the corresponding C70 Modes, that is consistent with the cluster-mass difference. We also noticed the lower scattering efficiency Of C60 than that of C70, except the pinch A(g) mode at 1468 cm-1.
MULTIPATH-FADING EFFECTS ON CARRIER RECOVERY OF BPSK SIGNAL IN DIGITAL RADIO
(1993-10-01)
LIU, GS
;
WEI, CH
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電控工程研究所
;
電信研究中心
;
Institute of Electrical and Control Engineering
Tracking performance of the I-Q carrier recovery loop for BPSK signal in bandlimited channel with multipath interference is analysed. The multipath fading channel is characterised by the Rummler's model (a simplified three-ray model) for fine-of-sight digital radio system. A closed-form expression for the phase-error variance related to the multipath interference, intersymbol interference and channel noise is derived. Excess phase offset induced from the multipath interference is also examined. The closed-form expression of the jitter variance can be evaluated numerically to assess the degradation of synchroniser performance. Asymptotic limits of the performance are also discussed.
SYNTHESIS OF A 90 K Y2BA4CU7O15-X SUPERCONDUCTOR UNDER AMBIENT-PRESSURE BY TRIETHYLAMMONIUMOXALATE COPRECIPITATION
(1993-10-01)
CHEN, TM
;
HO, JS
;
LIU, RS
;
KOO, HS
;
應用化學系
A 90 K superconducting Y2Ba4Cu7O15-x (247) powder with fine and homogeneous grain size was prepared by oxalate/triethylamine co-precipitation of a stoichiometric amount of mixed cations of yttrium, barium and copper from their aqueous solution of nitrate salts. Characterization results of the 247 superconductor by X-ray diffraction, electrical resistivity and magnetization measurements are reported. The intragrain critical current density (J(c)) of the as-prepared 247 superconductor was derived from magnetic hysteresis to be 8.5 X 10(6) A/cm2 at 5 K and 1 T. This new route may have considerable potential in the large-scale preparation of Y2Ba4Cu7O15-x.
CHARACTERIZATIONS OF OXIDE GROWN BY N2O
(1993-10-01)
CHAO, TS
;
CHEN, WH
;
SUN, SC
;
CHANG, HY
;
電控工程研究所
The constitution of N2O oxide has been investigated by using Auger analyses, ellipsometry measurement, and Fourier transform infrared (FTIR) spectroscopy in this paper. We found a nitrogen-rich layer formed at the interface of SiO2/Si by Auger analyses. From the results of ellipsometry, we found the thinner the N2O oxide, the larger the refractive index. A two-layer model construction of N2O oxide was proposed for modeling the interfacial layer. We found that this layer thickness is 14 to 20 angstrom when the refractive index was set to 1.77. FTIR analyses show that some of the Si-O bonds were replaced by Si-N bonds. This is the reason that N2O oxide has better electrical properties and a lower growth rate than those of the conventional dry 02 oxide.
AN ENACTABLE SOFTWARE PROCESS MODELING APPROACH
(1993-10-01)
CHEN, JY
;
LAI, CP
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Software process modelling has attracted much attention in the software engineering community in recent years. A software process model should be able to model distributed concurrent software processes. Moreover, it should be enactable. This article proposes a software process modelling approach which integrates three representations, namely, the Activity On Vertex net (AOV net), the Software Process Petri Net (SPPN), and the Concurrent Software Process Language (CSPL). First, the AOV net models take precedence and concurrency between process activities. Second, the AOV net is transformed into SPPN which models comprehensive information in the software process. Third, the SPPN is transformed into a CSPL process program which is executed in a distributed software development environment to enact a software process. Additionally, the modelling approach can analyse some undesirable states in the software process.
CARRIER-INDUCED ENERGY SHIFT IN GAAS/ALGAAS MULTIPLE-QUANTUM-WELL LASER-DIODES
(1993-10-01)
CHEN, PA
;
JUANG, C
;
CHANG, CY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Emission energy shift due to high carrier density at threshold in multiple quantum well (MQW) laser diodes is investigated theoretically. This energy shift is evaluated through the Schrodinger and the Poisson equations self-consistently as well as the calculation of the gain spectra with carrier-dependent lifetime broadening. The band filling and the gain broadening effects show a blue shift on the emission energy. Larger number of wells, lower barrier height, or wider well thickness, reduces the blue shift dependence on the carrier density. At high injections, this blue shift is offset by the bandgap shrinkage effect, which displays smaller influence on MQW's. While the carrier density is further increased, the transition due to the second quantized state is found in single quantum wells, however it is difficult to be observed in MQW's.
ROLE OF HYDROGEN AND OXYGEN IN DIAMOND SYNTHESIS USING CARBON-DIOXIDE METHANE-GAS MIXTURES
(1993-10-01)
CHEN, CF
;
HONG, TM
;
CHEN, SH
;
交大名義發表
;
材料科學與工程學系
A negative effect on the quality of diamond film because of the addition of hydrogen to carbon-dioxide-hydrocarbon gases was investigated. To elucidate the role of hydrogen and oxygen in diamond synthesis using microwave plasma chemical-vapor deposition, diamond films were deposited by adding hydrogen and oxygen to carbon-dioxide-methane-gas mixtures. Improvements in the quality of diamond film and extensions of the diamond-forming region were obtained, due to the addition of oxygen to the carbon-dioxide-methane-gas mixtures. The nucleation density of deposits increased when the amount of hydrogen was increased but decreased when the amount of oxygen was increased. The results of optical emission spectroscopy indicate that the amount of atomic hydrogen in the ground state remained nearly the same, respectively, with increasing amounts of hydrogen and oxygen. However, the amount of electronically excited atomic hydrogen and C2 emissions increased with an increase in the amount of added hydrogen; this means that the electronically excited atomic hydrogen did not benefit diamond growth and the C2 radicals facilitated the formation of amorphous or graphitic carbon. In contrast to the addition of hydrogen, when oxygen was added, the electronically excited atomic hydrogen and C2 radicals decreased, and a larger amount of oxygen-containing species such as atomic oxygen and OH radicals was in the plasma, so the quality of the diamond film improved. In summary, adding hydrogen to the carbon-dioxide-methane-gas mixtures had a negative effect on diamond growth, whereas adding oxygen had a beneficial effect.
NUMERICAL-SIMULATION OF THE SUPPRESSION OF SIDEGATING EFFECTS IN GAAS-MESFETS BY ION-BOMBARDMENT
(1993-10-01)
CHANG, SJ
;
LEE, CP
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effect of ion bombardment on sidegating effect in GaAs MESFETs has been studied by two-dimensional numerical simulations. Respective contributions of the bombardment induced electron traps, hole traps and neutral recombination centers to the suppression of sidegating effect in GaAs MESFETs have been studied. The increase of electron traps and the induced neutral recombination centers was found to be the main reason for the reduction of the sidegating effect. The results provide a further support to the sidegating picture in which Schottky contacts on the semi-insulating substrate play an important role.
A NOVEL PHL-EMITTER BIPOLAR-TRANSISTOR - FABRICATION AND CHARACTERIZATION
(1993-10-01)
CHANG, KZ
;
WU, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The polysilicon high-low-emitter (PHL-emitter) bipolar transistors have been fabricated and characterized. It is shown that the fabricated PHL-emitter bipolar transistors exhibit higher maximum current pin with lower activation energy, higher emitter-base breakdown, and better hot-carrier reliability than those of the fabricated conventional bipolar transistor. However, a little degradation in cutoff frequency for the fabricated PHL-emitter bipolar transistors due to the presence of the high-low emitter junction has also been observed. The effects of the n- implant dose on the electrical characteristics of the fabricated PHL-emitter bipolar transistors have been examined and discussed.
HYDROTHERMAL SYNTHESIS AND CRYSTAL-STRUCTURES OF BA2FE3H(PO4)2(P2O7)2 AND BA2V3H(PO4)2(P2O7)2
(1993-10-01)
DVONCOVA, E
;
LII, KH
;
LI, CH
;
CHEN, TM
;
應用化學系