Browsing by Issue Date, starting with "1991-04-01"

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EVAPORATIVE COOLING OF LIQUID-FILM THROUGH INTERFACIAL HEAT AND MASS-TRANSFER IN A VERTICAL CHANNEL .2. NUMERICAL STUDY
(1991-04-01)
YAN, WM
;
LIN, TF
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A numerical analysis is carried out to investigate the evaporative cooling of liquid falling film through interfacial heat and mass transfer in natural convection channel flows. Results for heat and mass transfer rates are specifically presented for the systems with ethanol film evaporation. The predicted results are also contrasted with the experimental results. The predictions show that the effects of the evaporative latent heat transfer on the cooling of the liquid film depend largely on the inlet liquid film temperature and liquid mass flow rate. Additionally, the results indicate that the heat transfer from the interface to the gas stream is predominated by the transport of the latent heat in conjunction with the liquid film evaporation.
DECOUPLING CONTROLLER-DESIGN FOR LINEAR-MULTIVARIABLE PLANTS
(1991-04-01)
LIN, CA
;
HSIEH, TF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We study decoupling controller design for linear time-invariant square MIMO plants under the unity-feedback configuration. For plants with no coincidences of unstable poles and zeros, we give a simplified necessary and sufficient condition for closed-loop stability. The simplified condition leads to a simple parametrization of the set of all achievable decoupled I/O maps and an algorithm which allows the design of decoupling controllers to achieve preassigned closed-loop poles.
FABRICATION AND PROPERTIES OF PLZT CERAMICS FROM SPRAY-DRIED AQUEOUS-SOLUTION
(1991-04-01)
CHIOU, BS
;
KUO, JN
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交大名義發表
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電控工程研究所
;
National Chiao Tung University
PLZT ceramics with the composition of 9/62/38 (La/Zr/Ti) were fabricated from spray-dried aqueous solution. Complete crystallization of the spray-dried powder is achieved after 1 hr calcination at 650-degrees-C as compared to 800-degrees-C, 1 hr for conventional mixed-oxide method. Sintering environment plays an important role in the densification of PLZT ceramics. Densities of the atmosphere sintered samples are much higher than those of normal sintered ones. PLZT ceramics derived from spray-dried powders have properties comparable to those derived from sol-gel ones. The spray-dried method presents a less expensive and more effective approach in the synthesis of PLZT ceramics.
2-DIMENSIONAL SIMULATION OF THE DRAIN-CURRENT TRANSIENT EFFECT IN GAAS-MESFETS
(1991-04-01)
LO, SH
;
LEE, CP
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
A two-dimensional numerical analysis of the drain-current transient behavior of ion-implantation GaAs MESFETs on undoped semi-insulating substrates is presented. It is found that the EL2 traps with slow transient behaviors play an important role in the drain lag effects. Also, the current overshoot and undershoot can be explained by the capture and the emission of electrons through the EL2 traps, respectively.
PRODUCTS OF UNIPOTENT MATRICES OF INDEX-2
(1991-04-01)
WANG, JH
;
WU, PY
;
交大名義發表
;
應用數學系
;
National Chiao Tung University
We show that an n x n complex matrix T is the product of two unipotent matrices of index 2 if and only if T is similar to a matrix of the form D + D-1 + (I + N) + (- I + SIGMA-i(m) = 1 + J(i)), where 0 and +/- 1 are not eigenvalues of D, N is nilpotent, and each J(i) is a nilpotent Jordan block of even size. On the other hand, T is the product of finitely many unipotent matrices of index 2 if and only if det T = 1. In this case, the minimal number of required unipotents is 1 if n = 1, 3 if n = 2, and 4 if n greater-than-or-equal-to 3.
WEIGHTED D-FILTERING
(1991-04-01)
WU, WR
;
KUNDU, AL
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
In this paper, we have proposed a new type of filter which has the most desirable properties of an image smoothing filter. These properties are 1) robust smoothing efficiency, 2) edge preservation, and 3) thin-line detail preservation. The new filter computes its output as the median of weighted averages, instead of plain averages as used in the Hodges-Lehman D-filter, of symmetrically placed order statistics. One particular weighting scheme is considered in details for experiments. The experimental and comparison results are included verifying the useful properties of the proposed filter.
COMPLEX-SURFACE MODELING WITH BIAS AND TENSION
(1991-04-01)
CHEN, DP
;
LIN, TL
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HSU, CC
;
交大名義發表
;
機械工程學系
The concept of applying bias and tension to cubic-spline curves for shape adjustment has been discussed in many papers in the literature, but few of them have mentioned any practical use of the parameter-controlled curves in surface modelling or mechanical-component design. In the paper, the influence of bias and tension on the shaping of the conventional cubic spline is investigated, and the tested values of the parameters are used in the surface models of various machine parts.
A NEW COMPOSITE BODY METHOD FOR MANIPULATOR DYNAMICS
(1991-04-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
This article presents a new composite body method for numerically forming the inertia matrix and the bias vector of manipulators, which is more efficient than the other two existing types of composite body methods. The main discrepancy of this one from the existing ones is that all points in a manipulator are observed from the origin of the base frame and the distances are all measured from this origin. The required computations of the present method for the inertia matrix and the bias vector of a manipulator with n rotational joints are (10.5n2 + 38.5n - 85)M + (6n2 + 39n - 70)A and (12.5n2 + 5.5n + 3)M + (9n2 + n)A, respectively, where "M" denotes multiplications, "A" does additions. In numerically forming the inertia matrix, the present method is more efficient than other methods in the literature for a manipulator with five or more joints; whereas this method is also superior to the recursive Newton-Euler formulation in computing the bias vector for a manipulator with six or less joints.
EVAPORATIVE COOLING OF LIQUID-FILM THROUGH INTERFACIAL HEAT AND MASS-TRANSFER IN A VERTICAL CHANNEL .1. EXPERIMENTAL-STUDY
(1991-04-01)
YAN, WM
;
LIN, TF
;
TSAY, YL
;
交大名義發表
;
機械工程學系
An experimental study is performed to study the evaporative cooling of the falling liquid film through interfacial heat and mass transfer in a vertical channel. The measured wall temperature, heat and mass transfer rates are specifically presented for the systems with water film evaporation and ethanol film evaporation over wide ranges of liquid mass flow rate, channel width and liquid inlet temperature. The results show that the influences of the evaporative latent heat transfer on the cooling of the liquid film depend largely on the inlet liquid film temperature and liquid mass rate. Effective evaporative cooling results for a higher inlet liquid film temperature and a smaller liquid mass flow rate.
EFFECT OF INORGANIC ELECTROLYTES ON THE RHEOLOGICAL PROPERTIES OF THE AQUEOUS YTTRIUM-OXIDE COLLOIDAL ZIRCONIA BINDER SOLS SYSTEM
(1991-04-01)
FRAN, YS
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TSENG, TY
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LIN, YL
;
CHANG, CP
;
交大名義發表
Multivalent ions such as La3+, Mg2+ function as surface-active counter ions for Y2O3 particles in aqueous solution. Due to the addition of these electrolytes, the solid content of Y2O3/ZrO2 binder sols slurry was increased and the stability of the slurry was improved. Both ion valence and ion size of electrolytes added into the slurry are expected to influence the slurry rheological flow behaviour.
A THERMAL PHASE-LOCKED LOOP FOR FREQUENCY STABILIZATION OF INTERNAL-MIRROR HE-NE LASERS (LAMBDA=0.633 MU-M)
(1991-04-01)
CHIEN, PY
;
PAN, CL
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交大名義發表
;
光電工程學系
;
National Chiao Tung University
A new servo circuit based on the thermal phase-locked loop (TPLL) has been developed for frequency stabilization of internal-mirror He-Ne laser. A feedback signal proportional to the fluctuation in the frequency of the laser is down-converted through a voltage-controlled oscillator (VCO) and compared in a phase/frequency circuit with that of a frequency reference. The detected phase difference then drives a heater wrapped around the laser tube for tuning the laser cavity length. The frequency stability achieved is +/- 1.0 x 10(-9) over a period of several hours.
NEW PHYSICAL TIMING MODELS OF BIPOLAR NONSATURATION LOGIC USING CURRENT DOMAIN ANALYSIS TECHNIQUE
(1991-04-01)
WU, CY
;
WU, TS
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new large-signal equivalent circuit with input and output current signals for a nonsaturated bipolar junction transistor has been developed. Based upon this equivalent circuit, physical timing models of direct-coupled transistor logic (DCTL) and nonthreshold logic (NTL) have been derived through a general modeling methodology. It is shown from extensive comparisons with SPICE simulation results that the models have a maximum error of 25% in single-stage delay calculation and 10% in multi-stage delay calculation. Experimental results on NTL ring oscillators also partly substantiate the developed current-domain large-signal equivalent circuit and physical timing models. Good accuracy, wide applicable ranges of device/circuit parameters and input waveforms, and less CPU time and memory consumption than full transient simulations make the physical timing models feasible in optimization and CAD of high-speed bipolar ICs.
ELECTRICAL CHARACTERISTICS OF DOUBLE-BARRIER RESONANT TUNNELING STRUCTURES WITH DIFFERENT ELECTRODE DOPING CONCENTRATIONS
(1991-04-01)
WU, JS
;
CHANG, CY
;
LEE, CP
;
CHANG, KH
;
LIU, DG
The electrical characteristics of AlGaAs/GaAs double-barrier resonant tunneling structures with various electrode doping concentrations have been studied. It was found that the peak current and the valley current are not sensitive to the change in the doping level of the electrodes. The peak-current voltage and the valley-current voltage, however, increase when the electrode doping level is lowered. These behaviors are explained using the band-bending effect in the electrodes. For devices with lightly doped or undoped electrodes, the quantum size effect in the accumulation layer due to the strong band bending causes additional kinks in the current-voltage characteristics. They are attributed to the resonant tunneling of electrons from the quantized levels in the accumulation layer. The quantum effect also accounts for the improved negative differential resistance behavior.
A BALANCED DUAL-PHOTODETECTOR OPTICAL RECEIVER FOR DAYLIGHT OPERATION
(1991-04-01)
CHIEN, PY
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
;
Department of Photonics
A balanced dual-photodetector optical receiver with an active optical feedback circuit suitable for daylight operation has been developed. This receiver is suitable for laser range finder or fuse systems operating under high level of sunlight illumination. The design and operation of the receiver is discussed.
AN INTEGRATED CAD SYSTEM FOR ALGORITHM-SPECIFIC IC DESIGN
(1991-04-01)
SHUNG, CB
;
JAIN, R
;
RIMEY, K
;
WANG, E
;
SRIVASTAVA, MB
LAGER is an integrated computer-aided design (CAD) system for algorithm-specific integrated circuit (IC) design, targeted at applications such as speech processing, image processing, telecommunications, and robot control. LAGER provides user interfaces at behavioral, structural, and physical levels and allows easy integration of new CAD tools. LAGER consists of a behavioral mapper and a silicon assembler. The behavioral mapper maps the behavior onto a parameterized structure to produce microcode and parameter values. The silicon assembler then translates the filled-out structural description into a physical layout and with the aid of simulation tools, the user can fine tune the data path by iterating this process. The silicon assembler can also be used without the behavioral mapper for high sample rate applications. A number of algorithm-specific IC's designed with LAGER have been fabricated and tested, and as examples, a robot arm controller chip and a real-time image segmentation chip will be described.
MODEL-REDUCTION FOR CONTINUOUS-TIME AND DISCRETE-TIME-SYSTEMS VIA SQUARED-MAGNITUDE RESPONSES MATCHING BY LINEAR-PROGRAMMING
(1991-04-01)
CHENG, MH
;
CHANG, JY
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交大名義發表
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電控工程研究所
;
National Chiao Tung University
The use of linear programming technique for the model reduction of continuous- and discrete-time systems is discussed. Based on squared-magnitude responses between the original system and its reduced model, a novel error function is presented. Two linear programming formulations are presented that use the L1-norm and the L infinity-norm of the proposed error function as respective criteria to solve the squared-magnitude problem. Finally, the reduced model is obtained by applying the factorization technique. Since the poles of the obtained squared-magnitude function are prevented from occurring on the j-omega axis (continous-time case) or unit circle (discrete-time case) by constraint, this approach ensures the stability of the reduced model. Some examples illustrate its applicability.
EFFECTS OF P+-IMPLANTED POLY-SI ELECTRODES ON THE GATE DIELECTRIC CHARACTERISTICS OF THIN OXIDES
(1991-04-01)
CHENG, HC
;
CHEN, WS
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Phosphorus implantation into polycrystalline silicon (poly-Si) has been used to dope the gate electrodes in poly-Si and polycide structures. Effects of phosphorus implantation conditions and post-implantation annealing on the time zero dielectric breakdown (TZDB) characteristics of gate oxides of thickness 10, 20 and 30 nm were investigated. Higher implantation energy and higher post-implantation annealing temperature result in worse TZDB properties of the gate oxides. Especially, the TZDB characteristics of 10-nm-thick oxides after annealing show a much more significant dependence on the phosphorus implantation energy and post-implantation annealing temperature than those of thicker oxides. Therefore, phosphorus diffusion into the SiO2/Si interface is the main cause of deterioration of the gate dielectrics. The thicker oxide has a higher endurance to the phosphorus diffusion and consequently achieves a better dielectric property for the higher energy implantation and higher temperature annealing conditions.
CAMERA CALIBRATION BY VANISHING LINES FOR 3-D COMPUTER VISION
(1991-04-01)
WANG, LL
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TSAI, WH
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
A new approach to camera calibration by vanishing lines is proposed. Calibrated parameters include the orientation, the position, and the focal length of a camera. A hexagon is employed as the calibration target to generate a vanishing line of the ground plane from its projected image. It is shown that the vanishing line includes useful geometric hints about the camera orientation parameters and the focal length, from which the orientation parameters can be solved easily and analytically. And the camera position parameters can be calibrated by the use of related geometric projective relationships. The simplicity of the target eliminates the complexity of the environment setup and simplifies the feature extraction in relevant image processing. The calibration formulas are also simple to compute. Experimental results show the feasibility of the proposed approach.
一首叫愛的詩已經刻好
(1991-04-03)
管管
ENERGY-STATES OF FINITE-BARRIER QUANTUM WIRES IN THE PRESENCE OF AN EXTERNAL ELECTRIC-FIELD
(1991-04-08)
JUANG, C
;
CHANG, CY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Energy level shift in finite-barrier quantum wires systems is found to be enhanced in comparison to finite-barrier single quantum well systems. The ground-state solutions of the two-dimensional Schrodinger equation are obtained using the inverse power method combined with the successive over relaxation method. In addition, the two-dimensional changes in the wave function due to an external electric field in cylindrical quantum wires are presented.