Browsing by Issue Date, starting with "1991-04-08"

Now showing 1 - 20 of 91287

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.
STYRENE MALEIC-ANHYDRIDE AND STYRENE GLYCIDYL METHACRYLATE COPOLYMERS AS INSITU REACTIVE COMPATIBILIZERS OF POLYSTYRENE NYLON 6,6 BLENDS
(1991-04-14)
CHANG, FC
;
HWU, YC
;
應用化學系
;
Department of Applied Chemistry
悲觀主義者學說
(1991-04-15)
管管
悲觀主義者學說
(1991-04-15)
管管
悲觀主義者學說
(1991-04-15)
管管
FORMATION OF PTSI-CONTACTED P+N SHALLOW JUNCTIONS BY BF2+ IMPLANTATION AND LOW-TEMPERATURE FURNACE ANNEALING
(1991-04-15)
TSUI, BY
;
TSAI, JY
;
CHEN, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the characteristics of PtSi-silicided p+n shallow junctions fabricated by implanting BF2+ ions into either the Pt/Si (ITM scheme) or the PtSi/Si (ITS scheme) structure followed by annealing in N2 furnace at temperatures from 650 to 800-degrees-C. For a structure with Pt film of 30 nm thickness or PtSi film of 60 nm thickness, the implantation energy ranges from 40 to 80 keV with a dose ranging from 1 x 10(15) to 1 x 10(16) cm-2. For the ITS samples with BF2+ implantation at 40 keV, all ions are confined in the PtSi layer; therefore, only a modified Schottky junction is formed by the diffusion of boron atoms from the PtSi film during the annealing. The junction depth may be as shallow as 30 nm from the PtSi/Si interface. A complete p+n junction is formed for the ITM samples with implantation at 40 keV as well as all the samples implanted at 80 keV. The junction thus obtained has a forward ideality factor lower than 1.02 and a reverse current density less than 0.2 nA/cm2 at -5 V. Activation energy measurement indicates that most of the implantation damages have been recovered after annealing at a temperature as low as 700-degrees-C. The reverse area and peripheral leakage current density are separated by measuring diodes of different perimeter/area ratio. For good samples, the reverse peripheral current comes from the surface generation current within the depletion region underneath the field oxide. All of the experimental results reveal that either Pt or PtSi film can be employed as an efficient barrier film in the ITM/ITS technique to form excellent and ultrashallow junctions with a low thermal budget.
悲觀主義者學說
(1991-04-15)
管管
PRECISION DISPLACEMENT MEASUREMENT BY ACTIVE LASER HETERODYNE INTERFEROMETRY
(1991-05-01)
LIN, YJ
;
PAN, CL
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
We demonstrate an active laser heterodyne interferometer which can automatically compensate environmental disturbances and is capable of precision displacement measurement. Two Zeeman He-Ne lasers were employed. Laser II was used as the light source to stabilize the interferometer by using a piezomirror in a feedback loop. The heterodyne signal of the two lasers was used to directly calibrate mirror displacement, with the wavelength of laser I tuned to compensate change in the interference signal due to displacement only. Separation of the contributions to the interference signal from displacement and external disturbances was accomplished by using polarization optics. This interferometer was used to measure the hysteresis of a piezoelectric transducer (PZT) over a dynamic range of 0.5-mu-m with a resolution of +/- 0.8 nm.
LOOP-BASED DESIGN AND RECONFIGURATION OF WAFER-SCALE LINEAR ARRAYS WITH HIGH HARVEST RATES
(1991-05-01)
CHANG, MF
;
FUCHS, WK
;
資訊工程學系
;
Department of Computer Science
Design and reconfiguration approaches for high harvest rates and parallel on-wafer diagnosis of linear arrays are described in this paper. The defect-tolerant designs employ multiplexors to switch intercell connections and guarantee that the wire length between any two logically adjacent cells is constant, independent of fault distribution. The designs are appropriate for implementing linear arrays of wafer-scale memory and processor architectures. The harvesting of fault-free cells into a linear array is a percolation process; there exists a critical cell yield such that the harvest rate drops to zero (approaches 100%) if the cell yield is below (above) the critical value. Finding a maximum-size linear array for a given set of fault-free cells is polynomial time solvable if only the interconnections between fault-free cells are utilized, but is NP-complete if the interconnections between all cells are utilized. A heuristic reconfiguration algorithm utilizing the interconnections between all cells is presented. Application of boundary scan to parallel testing and on-wafer diagnosis of the arrays is described.
EFFICIENT TECHNIQUES IN THE SIZING AND CONSTRAINED OPTIMIZATION OF CMOS COMBINATIONAL LOGIC-CIRCUITS
(1991-05-01)
HWANG, JS
;
WU, CY
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
Two techniques are proposed which enhance the optimisation efficiency of CMOS combinational logic circuits. One uses transition times (rise and fall times) of each gate as variables of the optimisation process. The other technique uses the optimal characteristic waveform synthesising method (OCWSM) to obtain the initial guess for the optimisation process. The optimisation process, with these two techniques, can perform sizing and optimisation for circuits with a smaller fixed-delay specification than other sizing and optimisation algorithms. The circuits sized using the proposed algorithm have shown a smaller power dissipation, especially when the delay specification is small. The CPU time consumed is reasonable. High-speed low-power circuits are thus more realisable using the proposed algorithm.
BEAMSPACE ML BEARING ESTIMATION INCORPORATING LOW-ANGLE GEOMETRY
(1991-05-01)
ZOLTOWSKI, MD
;
LEE, TS
;
電信工程研究所
;
Institute of Communications Engineering
A problem of interest in low-angle radar tracking is that of bearing estimation in the presence of a strong specular multipath component that arrives within a beamwidth of the direct path signal. Three-dimensional beamspace domain maximum likelihood (3D-BDML) is a computationally simple ML bearing estimation algorithm applicable in this scenario which operates in a 3-D beamspace. A variation of 3D-BDML incorporating the multipath geometry as a priori information is presented. In symmetric 3D-BDML the pointing angle of the center beam is equal to the bisector angle between the direct path ray and the image ray, which may be estimated a priori given only the radar height and the target range. The effect of the inclusion of a priori information on the performance of 3D-BDML is analyzed in terms of the dependence on the relative phase difference between the direct and specular path signals, the sensitivity to error in the bisector angle estimate, and the results of operation when no specular multipath component is present in the data. In addition, computationally simple schemes for coherently incorporating multifrequency data into 3D-BDML are investigated as well.
EFFECT OF BACK-GATE BIAS ON TUNNELING LEAKAGE IN A GATED P+-N DIODE
(1991-05-01)
CHEN, MJ
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
On a thin-oxide gate-controlled p+-n diode, this work first exhibits experimentally not only the substrate-bias-dependent characteristics of the tunneling leakage current but also the tunneling leakage characteristics independent of the substrate bias. This observation can be reasonably explained by the nature of the modulation of the surface space-charge region over the heavily doped p+ region as well as over the n-type substrate. Based on this work, the original understanding of such tunneling leakage has been improved.
DYNAMIC ANALYSIS OF PLANAR FLEXIBLE MECHANISMS BY COROTATIONAL FORMULATION
(1991-05-01)
HSIAO, KM
;
JANG, JY
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A co-rotational formulation of beam element and numerical procedure for the dynamic analysis of planar flexible mechanisms is presented. The nodal coordinates, velocities, accelerations, incremental displacements and rotations, and equations of motion of the system are defined in terms of fixed global coordinates, while the total strains in the beam element are measured in an element coordinate system which rotates and translates with the element but does not deform with the element. The element equations are constructed using the small deflection beam theory with the inclusion of the effect of axial force first in the element coordinate system, and then transformed to the global coordinate system using a standard procedure. In the proposed approach the resulting equations of motion are the same as those typically arising in nonlinear structural dynamics. An incremental-iterative method based on the Newmark direct integration method and the Newton-Raphson method is employed here for numerical studies. Numerical examples are presented to demonstrate the accuracy and efficiency of the present method.
COMPUTER-AIDED-DESIGN TOOL FOR SIMPLIFICATION OF ROBOT DYNAMIC-MODEL BASED ON MANIPULATOR SYSTEM PERFORMANCE
(1991-05-01)
CHANG, PR
;
交大名義發表
;
電信工程研究所
;
National Chiao Tung University
;
Institute of Communications Engineering
The dynamic performance of a robot manipulator is directly dependent on the efficiency of the controller and the dynamic model of the robot. This paper addresses the fundamental issue of how much manipulator dynamics information should be included in the manipulator dynamic model for control such that the manipulator will achieve the desired system performance under a proportional-plus-derivative control scheme. An efficient minimax simplification scheme has been developed which automatically generates simplified closed-form manipulator motion equations in symbolic form while maintaining the desired manipulator system performance under a proportional-plus-derivative controller. The scheme involves the identification and selection of basis functions that represent the dynamic coefficients in the dynamic model. These basis functions consist of a linear combination of the product terms of sinusoidal and polynomial functions of the generalized coordinates and form a Chebyshev set on the workspace of the manipulator. A multi-layered decision scheme is developed for selecting significant basis terms in each layer for each dynamic coefficient. The linear combination of these significant basis terms is then utilized to construct each simplified dynamic coefficient based on the minimax approximation technique. A verification of the proposed scheme on a Stanford robot arm is included for discussion.
PHOTOACID CATALYZED MAIN CHAIN SCISSION OF POLY(BUTENE-1 SULFONE) AS A DEEP UV POSITIVE RESIST
(1991-05-01)
LOONG, WA
;
CHANG, HW
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Poly(butene-1 sulfone) (PBS), a sensitive e-beam and X-ray resist, is inert to UV light. We found that the addition of a small amount of photoacid, triphenylsulfonium hexafluoroarsenate (TPSHFA), to PBS can catalyze its main chain scission via C-S bond cleavage by 254 nm deep UV exposure and concurrent baking at 80-degrees-C. Therefore, PBS can be used as a deep UV positive resist. The chemistry and resist characteristics of the PBS + TPSHFA system are discussed.
SELF-BENDING AND ASYMMETRIC SPATIAL SELF-PHASE MODULATION EFFECTS IN NEMATIC LIQUID-CRYSTAL FILMS
(1991-05-01)
PAN, RP
;
CHEN, SM
;
PAN, CL
;
電子物理學系
;
光電工程學系
Laser-induced beam bending and the far-field asymmetric diffraction ring pattern due to the self-bending and asymmetric spatial self-phase modulation (SPM) effects in nematic liquid-crystal films are investigated. The measured far-field patterns are in good agreement with numerical calculations based on the diffraction theory, taking into account the two dimensionally of the problem, the nonlocal effect, and the wave-front curvature effect. The individual contributions of the aforementioned effects to the far-field pattern are analyzed for the first time. It is shown that the outermost diffraction peak of the far-field pattern is not the strongest one and that a large fraction of the transmitted intensity remains in the central region (within +/- 6 mrad of the beam axis). Merging of some of the diffraction peaks in this region should also occur. Although the transmitted beam does deflect, the deflection angle does not increase monotonically with the incident laser intensity, as is the case for a purely Kerr-like medium. In the experiments discussed here, higher-order effects are present. As an example, it is shown that equally pronounced third- and fifth-order nonlinear optical SPM effects are responsible for an observed five-ring asymmetric ring pattern.
ESTIMATING PIT-EXCAVATION VOLUME USING CUBIC SPLINE VOLUME FORMULA
(1991-05-01)
CHEN, CS
;
LIN, HC
;
土木工程學系
;
Department of Civil Engineering
Current methods used for estimating the volume of pit escavation assumes that the ground profile between the grid points is linear (based on the trapezoidal rule), or nonlinear (based on Simpson's 1/3 and 3/8 formulas). Generally speaking, the nonlinear profile formulas provide better accuracy than the linear profile formulas. However, all the methods mentioned have a common drawback: The joints (grid points) of any two straight lines (the trapezoidal rule), quadratic polynomials (Simpson's 1/3 formula), or cubic polynomials (Simpson's 3/8 formula) form sharp corners. Consequently, these models may not describe the ground profile well. In this paper, formulas based on an extension of the cubic spline polynomial are presented. The grid of this new method is constructed by choosing the variational points of the ground profile and then dividing the pit's area into rectangles of unequal size. Therefore, the new formulas can be used for estimating the excavation volume of a pit divided into a grid with unequal intervals. Further, due to the characteristics of the cubic spline polynomial, a curve modeled by this polynomial can match the ground profile well. The new formulas should provide better accuracy than the other methods mentioned.
MANEUVERING TARGET TRACKING USING IMM METHOD AT HIGH MEASUREMENT FREQUENCY
(1991-05-01)
GUU, JA
;
WEI, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In tracking a maneuvering target by a radar system, the measurement noise is significantly correlated when the measurement frequency is high. In this paper, a simple decorrelation process is proposed to enhance the interacting multiple model (IMM) algorithm to track a maneuvering target with correlated measurement noise. It is found that the decorrelation process may improve system performance significantly, especially in velocity and acceleration estimations.
REMOTE PASSWORD AUTHENTICATION WITH SMART CARDS
(1991-05-01)
CHANG, CC
;
WU, TC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A remote password authentication scheme based on the Chinese remainder theorem is proposed. The scheme can verify the remote password without verification tables. In the initial phase, the password generation centre generates and assigns a password corresponding to each user. The ideas of smart cards and the identity-based signature scheme introduced by Shamir are employed in this phase. Each user possesses a smart card for later login and authentication. In the login phase, the user submits the identity and password associated with the smart card. In the authentication phase, the system verifies the remotely submitted password to check if the login request is accepted or rejected. A signature scheme and communication timestamps are provided in the authentication phase against the potential attacks of replaying a previously intercepted login request.
TRANSIENT LAMINAR MIXED CONVECTIVE HEAT-TRANSFER IN A VERTICAL FLAT DUCT
(1991-05-01)
LIN, TF
;
YIN, CP
;
YAN, WM
;
機械工程學系
;
Department of Mechanical Engineering
Unsteady laminar aiding and opposing mixed convection heat transfer in a vertical flat duct is numerically investigated for an initially fully developed flow. Results indicate that unsteady heat transfer characteristics in the flow are principally determined by wall-to-fluid heat capacity ratios. Effects of the buoyancy and degree of asymmetric heating or cooling are rather insignificant. Correlation equations for the time variations of local Nusselt numbers with wall-to-fluid heat capacity ratios are proposed.