Browsing by Issue Date, starting with "1991-05-01"

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PRECISION DISPLACEMENT MEASUREMENT BY ACTIVE LASER HETERODYNE INTERFEROMETRY
(1991-05-01)
LIN, YJ
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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
;
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
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FUCHS, WK
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資訊工程學系
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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
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WU, CY
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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
;
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
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LEE, TS
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電信工程研究所
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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
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交大名義發表
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電控工程研究所
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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
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JANG, JY
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交大名義發表
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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
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交大名義發表
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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
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CHANG, HW
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交大名義發表
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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
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CHEN, SM
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PAN, CL
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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
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LIN, HC
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土木工程學系
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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
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WEI, CH
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電控工程研究所
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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
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WU, TC
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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 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
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YIN, CP
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YAN, WM
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機械工程學系
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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.
PHASE-SHIFTING SCATTER PLATE INTERFEROMETER USING A POLARIZATION TECHNIQUE
(1991-05-01)
SU, DC
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SHYU, LH
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交大名義發表
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光電工程學系
;
National Chiao Tung University
The structure of a conventional scatter plate interferometer is modified by a polarization technique, and a new type of phase shifting scatter plate interferometer is presented. It has both the merits of a conventional scatter plate interferometer and the phase shifting interferometric technique. The working of this interferometer is demonstrated.
SINTERING BEHAVIOR AND DIELECTRIC CHARACTERISTICS OF LITAO3 WITH THE ADDITION OF (MG2+TIO2)
(1991-05-01)
CHIOU, BS
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LIN, TY
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DUH, JG
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電控工程研究所
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Institute of Electrical and Control Engineering
Densified LiTaO3-type ceramics can be obtained by sintering at 900-degrees-C after the addition of MgF2 or (MgF2 + LiF) mixture. Partial hydrolysis of MgF2 produces an MgO layer on top of the sample. Space charge polarization occurs at high temperatures between the MgO layer and the LiTaO3 matrix, inducing a large dielectric constant predominating over the ferroelectric Curie peak of the sample. The TiO2 dopant lowers the Curie temperature of the sample as the cation concentration increases. In addition, it is observed that substitution of Ta ions with Mg ions results in the formation of Ta2O5.
A TIMING STABILIZED LASER DIODE BASED RANGE SIMULATOR
(1991-05-01)
CHIEN, PY
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交大名義發表
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光電工程學系
;
National Chiao Tung University
;
Department of Photonics
A timing stabilized laser diode based range simulator has been demonstrated. Range simulation is achieved by locking the time delay between the reference signal generator and the time base of the output light pulse using a double phase-lock-loop. Phase stabilization to within 1.0 x 10(-5) rad Hz-1/2 has been implemented within the range - pi to + pi rad.
FORMATION OF COBALT SILICIDE UNDER A PASSIVATING FILM OF MOLYBDENUM OR TUNGSTEN
(1991-05-01)
YANG, FM
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CHEN, MC
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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 very simple and reproducible cobalt silicide process with Mo/Co or W/Co bilayer metallization to overcome the oxidizing liability of Co annealed in a normal flowing-nitrogen furnace has been developed. Cobalt is deposited on blank and patterned silicon wafers in an electron-beam evaporation system followed by Mo (or W) deposition without breaking the vacuum. The cobalt silicidation is carried out using a two-step annealing process. The first annealing is performed at a temperature ranging from 400 to 600-degrees-C, during which the role of the upper layer of Mo (or W) is to protect the underlying Co layer from being oxidized while not disturbing the cobalt's silicidation process. Perfect selective etching of Mo (or W) can be accomplished by a NH4OH + H2O2 + (2-3)H2O solution. The second annealing is performed at a higher temperature of 750-degrees-C to completely transform the CoSi obtained in the first annealing into CoSi2 and induce grain growth of CoSi2, thus lowering the resistivity. X-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and sheet resistance measurement are used to characterize the silicide phase and microstructure.
GAIN MARGINS AND PHASE MARGINS FOR SAMPLED-DATA CONTROL-SYSTEMS WITH ADJUSTABLE-PARAMETERS
(1991-05-01)
CHANG, CH
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HAN, KW
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a method for finding the boundaries of constant gain margin and phase margin of sampled-data control systems. The considered systems are first modified by adding a gain-phase margin tester, then the characteristic equations are formulated and factored into stability equations, and finally the parameter-plane method is used to find the boundaries of constant gain margin and phase margin. The main advantage of the presented method is to obtain complete information about effects of adjustable and/or variable parameters on gain margins and phase margins.
ABDUCTIVE REASONING BY CONSTRUCTING PROBABILISTIC DEDUCTION GRAPHS FOR SOLVING THE DIAGNOSIS PROBLEM
(1991-05-01)
LI, HL
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YANG, CC
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交大名義發表
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資訊管理與財務金融系註：原資管所+財金所
;
National Chiao Tung University
An algorithm is proposed for finding optimal solutions of the diagnosis problem by using deduction graphs (DG) to accomplish abductions of multiple causes and multiple symptoms. The relationship among causes, symptoms, and possible intermediaries is represented by a causal network. The algorithm accomplishes the abduction by constructing a deduction graph DG(C,S) from the cause set C to the symptom set S representing the subnetwork such that the product of the prior probability, P(C), of C and the conditional probability, P(SC), of DG(C,S) is maximized. An optimal solution is achieved by solving a 0/1 linear integer programming problem. Based on some assumptions, the algorithm can deal with a causal network involving various mutually independent deduction graphs.
A TRANSIENT NATURAL-CONVECTION IN AN ANNULAR ENCLOSURE
(1991-05-01)
FU, WS
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JOU, YH
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LEE, CH
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交大名義發表
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機械工程學系
A transient natural convection in an annular enclosure is investigated numerically. The upper and lower walls are adiabatic, the outer wall is maintained at a low temperature and the temperature of the inner wall is changed to a high value abruptly. During the computing process, the numerical method of SIMPLE-R with power law scheme is adopted to solve the axially-symmetric governing equations of the continuity, momentum and energy. The Rayleigh number of 10(4) and 10(6) are considered, respectively. Since the area of the annular cross section enlarges with the increasing of the radius, the phenomena occurring in the annular enclosure are different from those occurring in the rectangular enclosure. In addition, the results show that in the initial region the variations of the total Nusselt of the inner wall rebounds under Rayleigh number of 10(6) case and does not fluctuate under Rayleigh number of 10(4) case, which are similar to those of the rectangular enclosure.