Browsing by Issue Date, starting with "1997-05-01"

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Blind identification and deconvolution algorithms using higher-order cumulants
(1997-05-01)
Ueng, FB
;
Su, YT
;
電信工程研究所
;
Institute of Communications Engineering
The use of second-order statistics in identification or deconvolution incurs error due to additive Gaussian noise. In contrast, higher-order statistics (HOS) are insensitive to Gaussian perturbation and can be used to characterize nonminimum phase (NMP) systems. In this paper we propose batch, recursive and adaptive form algorithms based on third- and fourth-order cumulants to solve the identification and deconvolution problems. A new order determination procedure is also presented. Simulation results demonstrate that our algorithms do have superior performance when compared with existing algorithms.
Isometric muscle strength of Chinese young males in Taiwan
(1997-05-01)
Chuang, MC
;
You, ML
;
Cai, DC
;
Chen, CC
;
應用藝術研究所
This paper represents the results of an anthropometric measurement of the isometric muscle strength of Chinese young males in Taiwan aged from 16 to 20 years. The study uses a sample of 120 male students and measures four types of muscle strength: (1) right arm strength in exerting pull, push, adduction, abduction, lift, and press directions with five elbow angles (60, 90, 120, 150 and 180 degrees) in seated posture; (2) grip strength of both hands; (3) backlift strength; and (4) chest expanding strength. The obtained data are analysed and listed. Comparisons are made between the results of this study and those from domestic and foreign studies available in the literature. Tn general, their pattern is similar, but values obtained in this study are relatively smaller than those obtained in western countries.
Scattering analyses of asymmetric conductor-backed CPW open-end discontinuity problem
(1997-05-01)
Liu, SP
;
Tzuang, CKC
;
交大名義發表
;
電信工程研究所
;
National Chiao Tung University
The space-domain integral equation method using the generalized scattering matrix description of microwave passive circuits is employed to investigate the mode conversion of a CBCPW open-end discontinuity with unequal side plane widths. The conversion into two additional dominant modes, the c-mode-like mode and the pi-mode-like mode, and into the transmitted microstrip mode from an incident CPW mode is studied against side plane width, degree of asymmetry, substrate thickness, and frequency. Theoretical results are in excellent agreement with experimental ones.
The role of resist for ultrathin gate oxide degradation during O-2 plasma ashing
(1997-05-01)
Chien, CH
;
Chang, CY
;
Lin, HC
;
Chiou, SG
;
Huang, TY
During ashing process, resist has been intuitively regarded as a protection layer and deliberately removed in previous studies by wet process prior to plasma exposure in an effort to amplify the damage effect, Recently, we found instead that resist does not simply act as a protection layer, This newly observed phenomenon cannot be explained by the well-known electron shading effect which should not affect the area-intensive antenna structure used in our study, In this letter, we hypothesize that this resist-related charging damage is determined by the plasma potential adjustment difference between those devices with and without resist overlayer, The experimental results show a good correlation with our explanation, To be specific, severe antenna area ratio (ARR) dependent degradation of thin gate oxide is induced during the initial ashing stage while the resist is still on the electrodes, not during the overashing period.
Atomic-level investigation of the growth of Si/Ge by ultrahigh vacuum chemical vapor deposition
(1997-05-01)
Lin, DS
;
Miller, T
;
Chiang, TC
;
物理研究所
;
Institute of Physics
Si and Ge films can be prepared under ultrahigh vacuum conditions by chemical vapor deposition using disilane and digermane as source gases. These gases offer a high sticking probability, and are suitable for atomic layer epitaxy. Using synchrotron radiation photoemission spectroscopy and scanning tunneling microscopy, we have examined the surface processes associated with the heteroepitaxial growth of Ge/Si. The measured surface-induced shifts and chemical shifts of the Si 2p and Ge 3d core levels allow us to identify the surface species and to determine the surface chemical composition, and this information is correlated with the atomic features observed by scanning tunneling microscopy. Issues related to precursor dissociation, attachment to dangling bonds, diffusion, surface segregation, growth morphology, and pyrolytic reaction pathways will be discussed. (C) 1997 American Vacuum Society.
Intrinsic thermal stability and quenching recovery of thin-film superconductors with thermal boundary resistance
(1997-05-01)
Wu, JP
;
Chu, HS
;
機械工程學系
;
Department of Mechanical Engineering
The stability behaviour of a thin-film superconductor under a localized release of thermal disturbance is investigated. Two-dimensional conjugate film/substrate conduction equation with anisotropic thermal conductivity of the film, and Joule heat are employed to investigate effects of substrate and thermal properties on the intrinsic stability and quenching recovery. To consider the thermal boundary resistance between film and substrate, an interfacial-layer model (ILM) with very low diffusivity and an acoustic mismatch model (AMM) are employed. Results show that the thermal boundary resistance influences strongly the intrinsic stability. Thermal boundary resistance increases intrinsic stability if the thermal conductivity of the substrate or the disturbance energy is large. Higher Riot numbers and thermal conductivity ratios of film to substrate in longitudinal direction influence stability favorably. We demonstrate also that operation of a film/substrate system, such as YBCO/MgO, is either intrinsically stable or irrecoverably unstable.
Design of a resonant-cavity-enhanced photodetector for high-speed applications
(1997-05-01)
Tung, HH
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We present a theoretical study of the effects of light field distribution on the frequency response of a resonant-cavity-enhanced p-i-n photodetector, Taking advantage of the flexibility of cavity design, one can tailor the light field distribution in the absorption region, Because of the difference in velocities of the carriers, the speed performances of the detector depend on the field distribution and the cavity design, The results of our work indicate that when the maximum of light field intensity happens near the p(+) edge of the depletion layer, the device shows the best speed performance, The frequency response, the impulse response, and the step response have been calculated for different structures to demonstrate the importance of the field distribution.
An Authentication Protocol Without Trusted Third Party
(1997-05-01)
Shieh, Shiuh-Pyng
;
Yang, Wen-Her
;
Sun, Hun-Min
;
資訊工程學系
;
Department of Computer Science
A secure authentication protocol which supports both the privacy of messages and the authenticity of communicating parties is proposed. The trusted third party (key information center) is not needed once the secure network system is set up. Mutual authentication and key distribution can be achieved with two messages merely between two parties involved.
Using knowledge-based techniques on loop parallelization for parallelizing compilers
(1997-05-01)
Yang, CT
;
Tseng, SS
;
Chuang, CD
;
Shih, WC
;
資訊工程學系
In this paper we propose a knowledge-based approach for solving data dependence testing and loop scheduling problems. A rule-based system, called the K-Test, is developed by repertory grid and attribute ording table to construct the knowledge base. The K-Test chooses an appropriate testing algorithm according to some features of the input program by using knowledge-based techniques, and then applies the resulting test to detect data dependences for loop parallelization. Another rule-based system, called the KPLS, is also proposed to be able to choose an appropriate scheduling by inferring some features of loops and assign parallel loops on multiprocessors for achieving high speedup. The experimental results show that the graceful speedup obtained by our compiler is obvious.
Fully normalized spherical cap harmonics: Application to the analysis of sea-level data from TOPEX/POSEIDON and ERS-1
(1997-05-01)
Hwang, CW
;
Chen, SK
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
We introduce two sets of fully normalized harmonics for the spectral analysis of functions defined on a spherical cap. The harmonics are the products of Fourier functions and the fully normalized associated Legendre functions of non-integer degree. Using Sturm-Liouville theory for boundary-value problems, we present two convenient and stable formulae for computing the zeros of the associated Legendre functions that form two sets of orthogonal functions. Formulae for the stable numerical evaluation of the fully normalized associated Legendre functions of non-integer degree that avoid the gamma function are also derived. The result from the expansions of sealevel anomaly from altimetry into Set 2 fully normalized cap harmonics shows fast convergence of the series, and the degree variances decay rapidly without aliasing effects. The zero-degree coefficients (Set 2) of sea-level anomaly from TOPEX/POSEIDON (T/P) and ERS-1 indicate an El Nino event during 1993 January-1993 July, and a La Nina event during 1993 November-1994 July, although the ERS-1 result is less obvious. Ocean circulations over the South China Sea and the Kuroshio area are clearly identified with the low-degree expansions of sea-surface topography (SST) from T/P and ERS-1. A cold-core eddy of 4 degrees in diameter centred at 17.5 degrees N, 118 degrees E was detected with the expansion of SST from T/P cycle 47, and a property of the cap harmonics is used to compute this eddy's kinetic energy. The kinetic energy is at a low in winter and high in summer, and its variation seems to be periodic with an amplitude of 0.4 m(2) s(-2).
Refractive-index measurement based on the effects of total internal reflection and the uses of heterodyne interferometry
(1997-05-01)
Chiu, MH
;
Lee, JY
;
Su, DC
;
光電工程研究所
;
Institute of EO Enginerring
A new method for measuring the refractive index is presented, First, the phase difference between s and p polarizations that is due to the total internal reflection is measured by heterodyne interferometry. Then, substituting this phase difference into the Fresnel equations, we can obtain the refractive index of the test medium. (C) 1997 Optical Society of America.
A synthesis of 6-myoporol
(1997-05-01)
Ho, TL
;
Chein, RJ
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
An approach to (+/-)-6-myoporol (1) featured stereocontrol by equilibration of 2,6-disubstituted cyclohexanones to mainly the cis isomer. The synthesis was completed by reaction of a lactone intermediate with 3-lithiofuran, Mitsunobu reaction, and hydrolysis.
Design of a permanent/electromagnetic magnetic bearing-controlled rotor system
(1997-05-01)
Fan, YH
;
Lee, AC
;
Hsiao, FZ
;
機械工程學系
;
Department of Mechanical Engineering
This study proposes design procedures for the permanent-magnet-biased magnetic bearings (PEMBs) in rotor systems. Many aspects of designing magnetic bearings are discussed, e.g. the selection of a permanent magnet material, dimensions of electromagnets and permanent magnets, gap length, load capacity and maximum Ampere-turns. Linearization and DC current driver are the two constraints for determining feasible designs. According to an analytical model with a rigid body assumption for the rotor-bearing system, a decentralized output feedback control algorithm is employed to control this inherently unstable magnetic suspension rotor system. Experimental results indicate that the controlled rotor performs well at rotor speeds up to 12,000 rpm. (C) 1997 Published by Elsevier Science Ltd.
Refractive-index measurement based on the effects of total internal reflection and the uses of heterodyne interferometry
(1997-05-01)
Chiu, MH
;
Lee, JY
;
Su, DC
;
交大名義發表
;
光電工程學系
A new method for measuring the refractive index is presented, First, the phase difference between s and p polarizations that is due to the total internal reflection is measured by heterodyne interferometry. Then, substituting this phase difference into the Fresnel equations, we can obtain the refractive index of the test medium. (C) 1997 Optical Society of America.
Modeling and analysis of nonlinear guideway for double-ball bar (DBB) measurement and diagnosis
(1997-05-01)
Lai, JM
;
Liao, JS
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
The purpose of this paper is to study nonlinear geometric errors in multi-axis machine tools. A general mathematical model for guideway systems that can be applied to high-precision machine tools such as CNC lathes is introduced. Using this model, most nonlinear error sources in the guideway systems can be diagnosed by measuring the contouring error using a double-ball bar (DBB). Diagnostic software has been developed to identify system parameters based on the least-squares estimation method. Inputting two or three contouring errors pattern data into this software enables parameters to be identified quickly, based on the nonlinear model. (C) 1997 Published by Elsevier Science Ltd.
Reliability formulation for composite laminates subjected to first-ply failure
(1997-05-01)
Kam, TY
;
Chang, ES
;
機械工程學系
;
Department of Mechanical Engineering
Methods formulated on the basis of the concept of first-ply failure and the structural reliability theory are presented for the reliability analysis of laminated composite plates. In the reliability formulation, an appropriate phenomenological failure criterion is used to establish the limit state equation of the laminated composite plates, and different numerical techniques are employed to evaluate the reliability of the plates. Experimental investigations of lamina strengths and first-ply failure loads of laminated composite plates were performed. Baseline probability distributions of lamina strength parameters constructed from the test data are used to study the reliability of the laminated plates. The accuracy of the proposed models in reliability assessment of the laminated plates are verified by the experimental results on first-ply failure load distributions. (C) 1997 Elsevier Science Ltd.
First-ply failure strength of laminated composite pressure vessels
(1997-05-01)
Kam, TY
;
Liu, YW
;
Lee, FT
;
機械工程學系
;
Department of Mechanical Engineering
Strengths of laminated composite pressure vessels are studied via both analytical and experimental approaches. Experimental techniques are presented to determine the first-ply failure and burst strengths of laminated composite pressure vessels with different lamination arrangements. Different analytical methods, together with various failure criteria, are used to predict the first-ply failure strengths of the laminated pressure vessels. The accuracy of the theoretical prediction of first-ply failure strength is verified by the test data. The suitability of the failure criteria, as well as the limitations of the analytical methods are discussed. (C) 1997 Elsevier Science Ltd.
Leakage performance and breakdown mechanism of silicon-rich oxide and fluorinated oxide prepared by electron cyclotron resonance chemical vapor deposition
(1997-05-01)
Chang, KM
;
Wang, SW
;
Yeh, TH
;
Li, CH
;
Luo, JJ
The characteristics of silicon-rich oxide and fluorinated oxide (FxSiOy) films deposited in an electron cyclotron resonance chemical vapor deposition system with SiH4 and O-2 as the oxide sources and CF4 as the fluorinating precursor are investigated in this work. According to experimental results, the dangling bonds in Si-rich oxide behave as positively by charged electron traps and degrade the dielectric strength by lowering the barrier height for Fowler-Nordheim tunneling. On the other hand, a small amount of incorporated F atoms will passivate and neutralize these excess Si dangling bonds, thereby elevating the dielectric strength. However, too much incorporated F will degrade the pretunneling leakage performance owing to the porosity and fatigues structure in FxSiOy film. The high leakage and even breakdown at low field strongly limits the incorporated F concentration in FxSiOy film and the lowering of dielectric constant.
An examination of the wind-driven effect on the drift of precipitation particles using the Chung-Li VHF radar
(1997-05-01)
Chu, YH
;
Chen, TY
;
Lin, TH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
One of the essential assumptions made in estimating the terminal velocity and the drop-size distribution of hydrometeor from the precipitation Doppler spectrum observed by VHF/UHF radar (or wind profiler) is that all of the precipitation particles are moving together at the same velocity as the ambient wind. However, this may not be the case. In this paper, taking advantage of the capability of simultaneously measuring the motions of precipitation particles and the clear-air turbulence with a VHF radar, we develop a method to examine the wind-driven effect on the drift of precipitation particles using the Chung-Li VHF radar. By appropriately setting the radar parameters and steering the radar beams, experimental results show that the drift velocity of the precipitation particles in response to the drag force exerted by the background atmosphere is not the same as the ambient wind velocity, approximately 83% of the latter in this case. This feature indicates that the precipitation particles are not moving with the background wind, causing inaccurate estimations of the terminal velocity and the drop-size distribution of hydrometeor if this effect is not taken into account.
Effective microwave surface impedance of superconducting films in the mixed state
(1997-05-01)
Wu, CJ
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effective microwave surface impedance of mulitilayer structures made of high-ir, superconducting films in the mixed state, lossy dielectrics, and normal metals are theoretically calculated. The linear response of the superconductor to a microwave field is analyzed within both transmission line theory and the framework of self-consistent treatment of vortex dynamics reported by Coffey and Clem [18]. The microwave properties are investigated as a function of static field and film thickness for nonresonant structures. The effect of substrate thickness on the resonant phenomenon is carefully studied as well. Numerical results reveal that the substrate resonance in the Meissner state behaves like a parallel lumped-parameter resonantor, while in the vortex state it behaves as a series lumped resonant circuit. The basic distinction suggests that care should be taken in microwave applications when using superconducting films in the vortex state.