Browsing by Issue Date, starting with "1996-07-01"

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An innovation approach to optimize a Kalman filter with an H-infinity error bound by secant method
(1996-07-01)
Wu, BF
;
Hsu, HH
;
交大名義發表
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電控工程研究所
;
National Chiao Tung University
Designing a Kalman filter with a constraint on the H-infinity norm of the estimation error was first developed by Bernstein and Haddad in 1989. The main result is a sufficient condition for characterizing the Kalman filter. In this paper, similar to the standard Kalman filter, the properties of orthogonal principles are also shown to be preserved. Furthermore, the uniqueness, as opposed to an H-infinity filter, of the filter is implied by the orthogonal principles. An innovative approach to obtaining the minimum energy with a constraint on the H-infinity norm of the estimation en ol is proposed since the original work of Bernstein and Haddad does not, in general, reach the minimum energy of the estimation error. By means of the Secant method, the energy of the estimation error can be reduced as much as possible, under the condition that the H-infinity error bound is still satisfied.
An improved dynamic model in integral equation methods for the characterization of discontinuities in planar circuits
(1996-07-01)
Sheen, JW
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Lin, YD
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電信工程研究所
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Institute of Communications Engineering
An efficient method to improve the integral equations method is presented in this article. A delta gap source generator and the fundamental mode sampling technique are employed. By employing this modified method, observation of the SWR and the creation of a large matrix in the conventional method employing a delta gap source generator are not necessary. Also, the modeling complexity and the time-consuming computation of the conventional method, which employs the semiinfinite traveling-wave mode, are avoided. In this article we use the coplanar waveguide short-end discontinuity as an example to describe this method in the spectral domain. Moreover, numerical results are compared with our experimental data and they show good agreement. (C) 1996 John Wiley & Sons, Inc.
RWM-cut for color image quantization
(1996-07-01)
Yang, CY
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Lin, JC
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資訊工程學系
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Department of Computer Science
A new simple method for constructing a color palette that uses the radius weighted mean cut (RWM-cut) is proposed. The method is a hierarchically divisive method, and each two-class partition uses the centroid and the RWM only. Experiments show that the RWM-cut algorithm is feasible and visually acceptable. The algorithm can either be used alone or be used to create a good initial palette for the LBG algorithm. Besides the 3-D version, a 1-D version of the RWM-cut algorithm is also included in the paper for realtime color quantization. The quantization error is small and the processing speed is competitive. Dithered images are also provided. Copyright (C) 1996 Elsevier Science Ltd
Detail-preserving smoothing with morphology and fuzzy reasoning
(1996-07-01)
Lee, YG
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Hsueh, YC
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交大名義發表
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資訊工程學系
;
National Chiao Tung University
This study investigates a new approach to removing noise that preserves the fine details which are based on combination of mathematical morphology and fuzzy reasoning. We extract some features from an image using mathematical morphology, then input these features, and the image itself into fuzzy-rule-based systems to produce a more graceful image. (C) 1996 SPIE and IS&T.
Leakage current reduction in chemical-vapor-deposited Ta2O5 films by rapid thermal annealing in N2O
(1996-07-01)
Sun, SC
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Chen, TF
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電子工程學系及電子研究所
;
奈米中心
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Department of Electronics Engineering and Institute of Electronics
This study aims to improve the electrical characteristics and reliability of low-pressure chemical vapor deposited (LPCVD) Ta2O5 films by developing a new postdeposition single-step annealing technique. Experimental results indicate that excited oxygen atoms generated by N2O decomposition can effectively repair the oxygen vacancies in the as-deposited CVD Ta2O5 film, thereby resulting in a remarkable reduction of the film's leakage current. Two other post-deposition annealing conditions are compared: rapid thermal O-2 annealing and furnace dry-O-2 annealing. The comparison reveals that RTN(2)O annealing has the lowest leakage current, superior thermal stability of electrical characteristics and the best time-dependent dielectric breakdown (TDDB) reliability.
Coagulation of colloidal particles in water by chitosan
(1996-07-01)
Huang, CP
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Chen, Y
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交大名義發表
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環境工程研究所
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National Chiao Tung University
The feasibility of applying chitosan, as prepared from the crab chitin, was assessed in this study for the coagulation of colloidal particles. A series of batch flocculation tests with chitosan under different conditions was also conducted. The results indicate that chitosan is a potent coagulant for bentonite suspension. The relationship between the optimum chitosan dosage and the turbidity of the bentonite suspension is presented as a linear correlation. The evidence infers that an adequate range of the coagulant dosage is the primary consideration in determining the removal efficiency for the turbidity of the source water. It also indicates that the coagulation behavior for kaolinite by chitosan is different from that of bentonite, i.e., chitosan fails to form a good aggregate with kaolinite. Turbid water containing particles which show behavior similar to kaolinite apparently need to have some bentonite particles added as coagulant aid, thereby improving the aggregation of the colloid particles with chitosan. Moreover, the effect of pH on the coagulation efficiency of chitosan is insignificant. The evidence infers that charge neutralization is not a major mechanism controlling the formation of flee for chitosan coagulation.
Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber
(1996-07-01)
Liaw, SK
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Chen, YK
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光電工程學系
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Department of Photonics
A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported, In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved, This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.
Deep levels in SnTe-doped GaSb grown on GaAs by molecular beam epitaxy
(1996-07-01)
Chen, JF
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Chen, NC
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Liu, HS
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交大名義發表
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電子物理學系
A dominant deep level with an activation energy of 0.23-0.26 eV was observed by admittance spectroscopy in SnTe-doped GaSb layers grown directly on GaAs substrates by molecular beam epitaxy (MBE). The Sb-4/Ga Bur ratio was found to affect the Hall mobility and the concentration of the deep level in a similar way, with an optimal beam equivalent pressure ratio of around 7 obtained for GaSb grown at 550 degrees C, which should correspond to the lowest ratio at which a Sb-stabilized surface reconstruction can be maintained. This electron level is commonly detected in n-type (SnTe-, S- and Te-doped) GaSb, but not in undoped p-type GaSb, suggesting that the level is not a simple native defect, but may be connected with the impurity used for n-type doping of GaSb.
Microwave response of superconducting platelet crystals
(1996-07-01)
Wu, CJ
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Tseng, TY
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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 theoretical study of the microwave response of isotropic and anisotropic superconductors in the Meissner state is presented, We consider a superconducting thin platelet crystal oriented in a parallel field configuration. The linear response analysis is investigated on the basis of modified two-fluid models along with the diffusion equation. The CS coherence effect for conventional superconductors and the anomalous peak in the loss for anisotropic high-T-c. cuprates are considered. The microwave properties are analyzed by the derived dimensionless magnetic permeability. The results show that thin edges have essentially nothing to do with the microwave loss in isotropic superconductors and the simple slab geometry suffices in studying their microwave properties. As for the high-T-c superconductors, the anisotropic effect itself makes the thin edges crucial in determining the microwave loss. The, calculated results qualitatively indicate some good consistence with the reported experimental data. The role of thin edges of the superconducting platelet crystal in the microwave response is therefore evidently clarified.
A methodology for schedule compression
(1996-07-01)
Wu, HH
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Li, RK
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交大名義發表
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工業工程與管理學系
;
National Chiao Tung University
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
A behavior-based classification and retrieval technique for object-oriented specification reuse
(1996-07-01)
Chou, SC
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Chen, JY
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Chung, CG
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資訊工程學系
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Department of Computer Science
This paper presents a classification and retrieval technique for object-oriented specification reuse, based on the assumption that existing specifications exhibiting behaviors similar to that of the system under development are appropriate for reuse. Existing specifications are classified and retrieved according to the semantic networks abstracted from their behaviors. Since semantic networks attach semantic meanings to certain degrees of detail, our technique is rather precise. Primary behavior is used to classify specifications because it can be obtained in the early phases of system analysis. Therefore, our technique allows early reuse. Moreover, subspecifications and classes of existing specifications are classified independently so that they can be retrieved for reuse separately. Thus, our technique encourages reusing subspecifications as well as classes. Since a subspecification is composed of classes and their relationships, reusing it corresponds to reusing all those classes and relationships, A technique that reuses subspecifications as well as classes is thus expected to save more time than those that reuse only classes.
Numerical analysis of the transient behavior of the sidegating effect in GaAs MESFETs
(1996-07-01)
Chang, SJ
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Lee, CP
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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
Transient responses of sidegating effects in GaAs MESFETs are analysed using two-dimensional numerical simulations. Substrates with different trap conditions are considered to clarify the dominant processes in the sidegating transients. Particularly for the electron trap rich substrate (the commonly used undoped semi-insulating GaAs), transient sidegating responses under different bias conditions and the effect of sidegating on the active loads are analyzed to evaluate the effect of sidegating on circuits in operation. Copyright (C) 1996 Elsevier Science Ltd.
Off-axial pulse propagation in graded-index materials with Kerr nonlinearity - A variational approach
(1996-07-01)
Chien, CH
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Yu, SS
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Lai, YC
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Wang, JP
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光電工程學系
We analyze off-axial, self-focused pulse propagation in graded-index Kerr materials with the variational method. Equations which determine the characteristics of the beam, namely the optical path, the wavefront curvature, the beam width, and the pulse duration are derived and solved. We show that continuously adjustable negative group-velocity dispersion can be generated by off-axial propagation, and for pulse energy smaller than a critical value, negative group-velocity dispersion and Kerr nonlinearity warrant the existence of stable spatio-temporal solitary pulses.
High-frequency vortex response of anisotropic type-II superconductors
(1996-07-01)
Wu, CJ
;
Tseng, TY
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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
The theory of the self-consistent treatment of vortex dynamics developed by Coffey and Clem is extended to the case of anisotropic type-II superconductors. The vortex response to a microwave electromagnetic field is theoretically investigated based on the associated complex rf magnetic permeability of anisotropic superconductors. Microwave dissipation due to vortex motion is studied as a function of the temperature, de magnetic field, and microwave frequency. Comparisons of numerical results between anisotropic and isotropic superconductors are also given. The influence of the thin edge of superconducting platelets on the microwave properties is specifically examined as well. The extension presented provides the possible applicability in studying the high-frequency response of real anisotropic high-temperature superconducting single-crystal platelets in the mixed state.
A methodology for schedule compression
(1996-07-01)
Wu, HH
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
Dry etching of polysilicon with high selectivity using a chlorine-based plasma in an ECR reactor
(1996-07-01)
Chang, KM
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Yeh, TH
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Wang, SW
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Li, CH
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Yang, JY
Halogen-bearing gases have proved to be useful plasma discharge etchants for the fabrication of sub-micron poly-Si gate structures. In this paper, investigations of chlorine-based plasmas generated by an electron cyclotron resonance (ECR) reactor for poly-Si etching is studied. The influences of added oxygen, microwave power and RF power on etching characteristics are discussed. In addition, the etching mechanisms of the underlying oxide are developed. Finally, the Cl-2/HBr/O-2 mixed system is examined. The combined plasma exhibits the features of high selectivity, high anisotropy and high etching rate.
Properties of radio frequency magnetron sputtered silicon dioxide films
(1996-07-01)
Wu, WF
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Chiou, BS
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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
The rf sputtering method, using Ar/O-2 mixture, was applied to fabricate silicon oxide films. The compressive internal stresses, resulted from thermal expansion mismatch, of films deposited on polycarbonate are larger than those of films deposited on glass substrates. Addition of oxygen to the sputtering ambient reduces both the film deposition rate and grain size. The adhesion of the SiO2 film to the glass substrate are measured with pull-off test and/or scratch test. Films sputtered in the presence of oxygen are more wear-resistant than those without oxygen.
The construction of a 9-pole prototype for SRRC U-10 undulator
(1996-07-01)
Chang, CH
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Chang, LH
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Chen, HH
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Fan, TC
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Hwang, CS
A 9-pole undulator prototype with a magnetic period length of 10 cm was designed and constructed to examine the mechanical and magnetic field performance. The hybrid permanent magnet structure was optimized by using 2D ''PANDIRA'' and 3D ''TOSCA'' magnetostatic codes. A half period magnet model was also fabricated to verify the magnetic Period length field strength on-axis and the transverse field roll-off within 0.1 % in the good field region of +/- 10 mm at a minimum gap of 22 mm. The end pole configurations, as equipped with either two tunable permanent magnetic rotators or steering coil correctors were designed for minimizing the deviation of the magnetic field strength integrals. The magnet structures were mounted bn a 2 meter long C-frame support structure in which the gap could be moved in parallel and phase motion. The field characteristics, and measurement results between the adjustable gap undulator (AGO) and the hybrid adjustable phase undulator (APU) were also presented.
Encapsulation in object-oriented programs
(1996-07-01)
Chen, JL
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Wang, FJ
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交大名義發表
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資訊科學與工程研究所
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National Chiao Tung University
An efficient dynamic threshold scheme
(1996-07-01)
Hwang, SJ
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Chang, CC
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Yang, WP
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交大名義發表
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資訊工程學系
To improve the efficiency for the threshold schemes, the major problem is that the secret shadows cannot be reused after renewing or recovering the shared secret. However, if the secret shadows cannot be reused, the established threshold scheme is limited to be used only once. It is inefficient to reconstruct the whole secret sharing system. Therefore, we introduce an efficient dynamic threshold scheme. In the new scheme, the shadowholders can reuse the secret shadows no matter that the shared secret is renewed or recovered. In addition, the new scheme provides a way by which the dealer can renew the shared secret or reconstruct the secret sharing system, efficiently. Therefore, this scheme is good for maintaining the important secrets.