Browsing by Issue Date, starting with "1991-09-01"

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DOUBLE SPHERICAL-HARMONICS APPROXIMATION APPLIED TO COMBINED CONDUCTION-RADIATION IN A PLANAR MEDIUM
(1991-09-01)
TSAI, JH
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交大名義發表
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機械工程學系
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National Chiao Tung University
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Department of Mechanical Engineering
Steady, combined radiation and conduction heat transfer in an absorbing, emitting and anisotropically-scattering planar material is investigated theoretically. The medium boundaries are assumed with specified temperatures. Emitting and diffusely reflecting boundaries are considered. The influence of radiation heat transfer is obtained by solving the differential-integral equation with the double spherical harmonics (DP1) approximation technique. This technique reduces the integral-differential equation of radiative transfer into systems of first-order differential equations. The resulting set of coupled first order ordinary differential equations is solved as a boundary value problem utilizing software routines that are readily available. The integral energy equation is solved by the Simpson's method with an iterative procedure. In order to demonstrate the versatility and accuracy of the proposed methodology, the results of several numerical experiments are presented and compared with benchmark solutions. The method of solution is shown to be relatively simple and in close agreement with exact solutions.
DEVELOPMENT OF TEMPERATURE-STABLE THICK-FILM DIELECTRICS .3. ROLE OF GLASS ON THE MICROSTRUCTURE EVOLUTION OF A THICK-FILM DIELECTRIC
(1991-09-01)
CHIOU, BS
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LIU, KC
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DUH, JG
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CHUNG, MC
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電子工程學系及電子研究所
Glass phase plays an important role in the characteristics of thick-film microelectronics. A dielectric system in BaTiO3 and SrTiO3 containing PbO, B2O3, SiO2, and Al2O3 glass constituents is investigated. Microstructure evolution and phase distribution after thermal aging are studied with the aid of electron microscope and X-ray diffractometer. It is observed that the phases in 40 vol% BaTiO3-25 vol% SrTiO3-35 vol% glass thick-film dielectric are not altered after 500-degrees-C aging for 480 h. The variation in surface morphology after long time aging is attributed to the precipitation of heavy metal component from the glass which acts as a diffusion species and then dissolves the crystalline phase during firing. The presence of glass in the dielectric enhances the formation of solid solution (Ba(x)Sr1-x)TiO3 and results in the broadening of the Curie peak.
LATCHED CMOS DIFFERENTIAL LOGIC (LCDL) FOR COMPLEX HIGH-SPEED VLSI
(1991-09-01)
WU, CY
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CHENG, KH
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A new CMOS differential logic, called the latched CMOS differential logic (LCDL), is proposed and analyzed. LCDL circuits can implement a complex combinational logic function in a single gate, and form the pipeline structure as well. It is shown that the LCDL with a fan-in number between 6 and 15 has the highest operation speed among those differential logic circuits. It is also free from charge-sharing, clock-skew, and race problems. Experimental results have verified the high speed and race-free performance of the proposed LCDL.
SMOOTHED DPCM CODES
(1991-09-01)
CHANG, WW
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GIBSON, JD
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電信工程研究所
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Institute of Communications Engineering
Rate distortion theory promises that autoregressive sources can be encoded optimally at small distortions (high rates) by a source coder with infinite encoding delay and zero delay at the decoder. However, for instrumentable systems with finite encoding delay and an unmatched code generator or for operation at low rates, decoding delay may provide a performance increment. The alphabet constrained approach to data compression allows delay at both the encoder and the decoder, and Sethia and Anderson incorporate delay in a tree coder code generator by combining a weighted linear interpolation scheme with DPCM. This system, called interpolative DPCM (IDPCM), was shown to outperform DPCM at rate 1 b/sample for several synthetic source models. In the present work, we use minimum mean squared error (MMSE) fixed-lag smoothing in conjunction with DPCM to develop a code generator employing delayed decoding. This smoothed DPCM (SDPCM) code generator is compared to DPCM and IDPCM code generators at rates 1 and 2 b/sample for tree coding several synthetic sources and to a DPCM code generator at rate 2 b/sample for speech sources. The (M,L) algorithm, which retains only the M best paths to depth L, is used for tree searching, and SDPCM outperforms IDPCM and DPCM at rate 2 b/sample for the synthetic sources with M = 1, 4, 8, and 12, and at rate 1 b/sample with M greater-than-or-equal-to 4. For speech, SDPCM provides a slight improvement in MSE over DPCM codes that is also evident in sound spectrograms and informal subjective listening tests. The models upon which the fixed-lag smoother is based must be chosen appropriately to achieve good SDPCM performance.
NEW OBSERVATION OF GATE CURRENT IN OFF-STATE MOSFET
(1991-09-01)
CHEN, MJ
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交大名義發表
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電子工程學系及電子研究所
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National Chiao Tung University
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Department of Electronics Engineering and Institute of Electronics
For a gate-controlled p+-n diode having gate-p+ overlap area of 3.7 x 10(-4) cm2, the work reports a new observation of the leakage current through a 235-angstrom gate oxide: the gate current components both due to Fowler-Nordheim electron tunneling through the gate-p+ overlap oxide and due to hot-electron injection have been separately detected. The corresponding gate current has been found to be dominated by Fowler-Nordheim electron tunneling prior to significant surface avalanche impact ionization. This observation is important for device application and for reliability study.
A STUDY ON THE TOOTH GEOMETRY AND CUTTING MACHINE MECHANISMS OF SPIRAL BEVEL GEARS
(1991-09-01)
FONG, ZH
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TSAY, BCB
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交大名義發表
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機械工程學系
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National Chiao Tung University
The tooth geometry and cutting machine mechanisms of spiral bevel gears are investigated. Based on the kinematics of tilted head cutter, machine cradle, sliding base and work head, the matrix presentation of spiral bevel gear's tooth geometry are developed. The relations between the parameters of the proposed mathematical model and the machine settings of existing spiral bevel gear cutting machines are also investigated. The tilt of head cutter axis, motion of generation, helical motion of sliding base, and nongenerating cutting of spiral bevel gears are taken into consideration. An example is given to illustrate the application of the proposed mathematical model.
A MODIFIED TRANSFER-MATRIX METHOD FOR LINEAR ROTOR-BEARING SYSTEMS
(1991-09-01)
LEE, AC
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KANG, Y
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LIU, SL
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機械工程學系
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Department of Mechanical Engineering
The steady-state responses of linear flexible rotor-bearing systems are analyzed by the modified transfer matrix method. The transfer matrix has the advantage of solving the problems in frequency domain with fixed matrix size. This makes the method more economical in analyzing a large degree-of-freedom rotor system than many time-marching integrating methods. In this paper, the modifications of transfer matrix method include that the transfer matrix of shaft is derived from the "continuous system" concept instead of conventional "lumped system" concept, and the paper tries to extend the transfer matrix method to fit synchronous elliptical orbit and nonsynchronous multi-lobed whirling orbit. To demonstrate the applications of the method, three examples are presented; two synchronous and one nonsynchronous.
INSITU GROWTH OF SUPERCONDUCTING YBA2CU3O7-X THIN-FILMS
(1991-09-01)
HAUNG, CJ
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CHANG, CY
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CHEN, MC
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TSENG, TY
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電子工程學系及電子研究所
Using single-target on-axis sputter deposition, YBa2Cu3O7-x films, with flatness oriented in the c axis and a zero-resistance temperature (T(co)) of 89 K, were prepared by an in situ growth technique. This work examines the effect of the growth temperature on the properties of in situ films. The experimental results show that high-quality YBa2Cu3O7-x films can be obtained by controlling the substrate temperature in a range from 680-degrees to 690-degrees-C. In addition, a new parallel-circuit model is proposed and a simulation of the resistance versus temperature curve is presented.
GAS PERMEATION THROUGH A SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANE-BASED MEMBRANE
(1991-09-01)
CHEN, DS
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HSIUE, GH
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HSU, CS
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應用化學系
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Department of Applied Chemistry
A membrane was prepared by sandwiching the side-chain liquid-crystalline polysiloxane (LCP) 3 between two porous poly(propylene) (Celgard) films. Permeation properties for H-2, O2, N2, CH4 and CO2 through the side-chain LCP-based membrane was measured using a gas-chromatographic method at several different temperatures corresponding to the different states of of the side-chain LCP. The gas permeation behaviour depends strongly on the different states of the side-chain LCP. The plots of permeability versus reciprocal temperature show an abrupt change of the slope in the vicinity of the glass transition temperature (T(g)) of the side-chain LCP for all five gases. The activation energy for permeation obtained at these different states exhibits different values. The value obtained in the liquid-crystalline state is the highest. Separation factors (P(O2)/P(N2)) and (P(CO2)/P(CH4)) exhibit an unusual behaviour when the temperature changes across T(g). They increase abruptly when the temperature increases and the phase changes from the glassy state to the liquid-crystalline state of the side-chain LCP. The fact that both permeability and selectivity increases with increasing temperature above the glass transition is attributed to the supermolecular arrangement of the liquid-crystalline state of the side-chain LCP.
BUILDUP OF STEADY-STATE PICOSECOND PULSES IN AN ACTIVELY MODE-LOCKED LASER-DIODE ARRAY
(1991-09-01)
KUO, JC
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CHANG, CS
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PAN, CL
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交大名義發表
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光電工程學系
We have studied experimentally the temporal and spectral characteristics of an actively mode-locked laser-diode array in an external cavity as it evolves to the steady state. It is found that the buildup time to steady-state picosecond pulses takes less than 45 round trips. The number of clusters of the longitudinal-mode spectrum reduces during the evolution and finally approaches a steady-state spectral distribution with the pulse energy mainly distributed among a few clusters near the line center.
PHOTOREFRACTIVE MODE-COUPLING BETWEEN 2 UNIDIRECTIONAL RING OSCILLATORS
(1991-09-01)
DAI, LK
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GOU, YS
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YEH, P
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GU, C
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光電工程學系
We consider the coupling between two photorefractive unidirectional ring resonators. The first resonator is driven by an external laser beam via photorefractive two-wave mixing. The internal oscillating beam is then employed to drive the second ring resonator via the same mechanism. Closed form solutions for the oscillation intensities and frequencies are given, and their numerical results are presented and discussed. PACS: 42.65
MIXED-MODE SIMULATION OF DX TRAP-INDUCED SLOW TRANSIENT EFFECTS ON ALGAAS GAAS HEMT INVERTERS
(1991-09-01)
WANG, TH
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交大名義發表
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電子工程學系及電子研究所
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National Chiao Tung University
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Department of Electronics Engineering and Institute of Electronics
A mixed level device and circuit simulation has been performed to analyze DX trap-induced slow transient effects on the performance degradation of AlGaAs/GaAs HEMT circuits. The variation of the output pulsewidth and the hysteretic characteristics of the input-output voltage transfer function in DCFL HEMT inverters have been simulated. In the model, a DX trap rate equation is calculated in the AlGaAs layer. The self-consistent Schrodinger and Poisson equations are solved numerically at each cross section of a device. A two-region Grebene-Ghandhi model is employed to derive the I-V characteristics. Connections between individual HEMT devices in simulated circuits are treated as nodes of circuit equations. In the simulation, all of the device equations and the circuit equations are iteratively solved until a self-consistent solution is achieved. Our simulation confirms that the output pulse broadening and narrowing effects in a string cascaded DCFL HEMT inverters are a consequence of the inverter voltage transfer function shift caused by deep traps.
THE SIMULATION OF CONTRAST-ENHANCED LITHOGRAPHY
(1991-09-01)
LOONG, WA
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PAN, HT
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交大名義發表
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應用化學系
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National Chiao Tung University
The Dill's parameters of nonlinear photobleaching materials of p-diazo-N,N-dimethylaniline chloride zinc chloride (DZC) and poly(di-n-hexylsilane) (PDHS) are irregularly dependent on their film thickness, and also their refractive indexes change during exposure. These difficulties make Dill's model inadequate for the simulation of nonlinear photobleaching materials used in contrast-enhanced lithography. A direct approach was proposed to solve these difficulties. Equations with four parameters were derived to simulate the nonlinear photobleaching curves of DZC, PDHS and other nonlinear photobleaching curves reported in literature. The equations correlated verv well with these curves by using best-fit parameters. Linearity was found with these four parameters in these equations as a function of film thicknesses of DZC and PDHS. Based on this linearity, the modelling and simulation of these nonlinear photobleaching materials as contrast-enhancement layers are more convenient and accurate than those using Dill's model.
DESIGN OF INTEGRAL VARIABLE STRUCTURE CONTROLLER AND APPLICATION TO ELECTROHYDRAULIC VELOCITY SERVOSYSTEMS
(1991-09-01)
CHERN, TL
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WU, YC
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電控工程研究所
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Institute of Electrical and Control Engineering
An integral variable structure controller (IVSC) for robust servotracking is proposed. It comprises an integral controller, which is designed for achieving zero steady-state error under step input, and a variable structure controller (VSC) which is designed for enhancing robustness. A procedure is developed for determining the coefficients of the switching plane and the integral control gain such that the overall closed-loop system has the desired eigenvalues. Furthermore, a modified proper continuous function is introduced to overcome the chattering problem. An electrohydraulic velocity servocontrol system using the proposed IVSC approach is illustrated. Simulation results show that the proposed IVSC approach can achieve accurate servotracking and is fairly robust to plant parameter variations and external load disturbances.
PROCESSES OF TOP-IMAGED SINGLE-LAYER RESISTS BY POTASSIUM-ION TREATMENT IN SOLUTION
(1991-09-01)
LOONG, WA
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SU, AN
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WANG, JL
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CHU, CY
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交大名義發表
This paper presents new processes for the enhancement of oxygen reactive ion etching (RIE) resistance of two single-layer resist systems by selective incorporation of potassium ions into the resist image in solution after exposure. One resist system is diazonaphthoquinone (DAQ) and poly(p-formyloxystyrene) (PFS) mixed with a catalytic amount of triphenylsulfonium hexafluoroarsenate as a photoacid generator. After deep-UV exposure, the photoacid catalyzes the photo-Fries rearrangement of PFS to form poly(p-hydroxystyrene) (PHS); DAQ rearranges to form indene carboxylic acid and grafts into PHS via S-O bond formation. A latent image is formed by selective reaction of carboxylic groups with C5H11COOK in aqueous solution in exposed areas which are resistant to oxygen RIE. Dry developed negative-tone patterns are obtained by oxygen RIE. The other resist system is AZ1350J, dipping in C23H47COOK in hexane after deep-UV exposure. C23H47COOK selectively incorporates into unexposed areas only. Dry developed positive-tone patterns are obtained by oxygen RIE in this case.
STABILITY OF A HEDGEHOG NEMATIC CONFIGURATION IN A SMALL CLOSED CYLINDRICAL CAVITY
(1991-09-02)
CHEN, SH
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LIANG, BJ
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交大名義發表
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光電工程學系
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National Chiao Tung University
This letter presents a study on the stability of molecular configurations in a small closed nematic liquid-crystal cell. A volume point defect exists at the center of the cell with the molecules anchored perpendicularly to the cavity wall. We show that the transformation of a radial hedgehog to a hyperbolic one should occur when the ratio of splay-to-bend elastic constants becomes larger than a certain value that depends on the cell geometry.
BOLOMETRIC YBA2CU3O7-X INFRARED DETECTOR
(1991-09-12)
TSENG, TY
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CHANG, CY
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HAUNG, CJ
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CHEN, MC
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電子工程學系及電子研究所
Results of the measurement of optical detection in YBa2Cu3O7-x superconducting epitaxial films at a wavelength of 0.94-mu-m are presented. These films show bolometric responses at temperatures in the resistive transition regions which are strongly dependent on the bias current. For 0.94-mu-m radiation, electronically chopped at 20 Hz, measurement of a meander bridge yields a bolometric responsivity of approximately 6.1 V/W.
FINDING THE MOST VITAL EDGE WITH RESPECT TO MINIMUM SPANNING TREE IN WEIGHTED GRAPHS
(1991-09-13)
HSU, LH
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JAN, RH
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LEE, YC
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HUNG, CN
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CHERN, MS
EFFECT OF POLYCARBONATE MOLECULAR-WEIGHT ON PRECRACK HYSTERESIS ENERGY IN DETERMINING ITS DUCTILE-BRITTLE TRANSITION
(1991-09-20)
CHANG, FC
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HSU, HC
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交大名義發表
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應用化學系
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National Chiao Tung University
The distinctive ductile-brittle transition behavior of pseudoductile polymeric materials such as polycarbonate (PC) has been discovered to be closely related to the precrack hysteresis loss energy. The higher molecular weight (MW) PC with higher ductility also results in higher precrack hysteresis energy and therefore greater precrack plastic volume under condition of constant loads. If the precrack plastic volume exceeds a critical value, crack initiation thereafter will propagate within the domain of the plastic zone and results in ductile fracture. The deformation displacement is closely related to the precrack plastic volume, and the critical displacement actually determines the critical plastic volume. The higher molecular weight polycarbonate with higher entanglement density is able to withstand earlier crack initiation more effectively. Toughening plastics, such as rubber modification, is simply the result of delaying or retarding the crack initiation and allows the precrack plastic zone to grow over its critical value. A model of crack criterion based on precrack plastic zone is proposed to interpret the ductile-brittle transition phenomenon.
PARAMETRIC NONLINEAR INTEGER PROGRAMMING - THE RIGHT-HAND SIDE CASE
(1991-09-25)
CHERN, MS
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JAN, RH
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CHERN, RJ
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資訊工程學系
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Department of Computer Science
In this paper, we present algorithms for solving families of nonlinear integer programming problems in which the problems are related by having identical objective coefficients and constraint matrix coefficients. We consider two types of right-hand sides which have the forms b(l) and b(i) + theta-i(d)i where {b(l)}l = 1,...,L is a given set of vectors, b(i) + theta-i(d)i is a parametric function and the parameter theta-i varies from zero to one. The approach consists primarily of solving the most relaxed problem using branch and search method and then finding the optimal solutions of the proposed parametric programming problems. The application of this methodology to a parametric chance-constrained problem is illustrated with applications in system reliability optimization problems.