Browsing by Issue Date, starting with "1997-03-24"

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The role of transesterification on the miscibility in blends of polycarbonate and liquid crystalline copolyester
(1997-03-24)
Wei, KH
;
Ho, JC
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
Transesterification mechanisms and rate in blends of polycarbonate (PC) and random liquid crystalline polyester copoly(oxybenzoate-p-terephthalate) at molar ratio 40/60 (P46) were studied through a five-component diad analysis and with C-13 and H-1-C-13 nuclear magnetic resonance spectroscopy. It was found that the ester-ester interchange in the two polymers took place within 15 min when the blend was annealed at 260 degrees C in vacuum. In the annealed blend, the Bisphenol A unit in polycarbonate reacted first with the terephthalate unit and then with the oxybenzoate unit in copoly(oxybenzoate-p-terephthalate). As the transesterification in the blend continued for about 1 h, the forming of dad Bisphenol A-oxybenzoate exceeded that of diad Bisphenol A-terephthalate. This large loss (57%) of the diad oxybenzoate-oxybenzoate caused the disappearance of the liquid crystalline phase in the blend. In sharp contrast to the originally immiscible blend of PC and P46 (two distinctive glass transition temperatures), the large loss of the liquid crystalline diad resulted in complete miscibility in the annealed blend, as evidenced by the appearance of a single glass transition temperature in the differential scanning calorimetry measurement.
管管的法國梧桐不同
(1997-03-24)
管管
老秋
(1997-03-24)
管管
Physical characteristics of N-2 annealing on room-temperature-deposited ion plating oxide
(1997-03-24)
Yeh, CF
;
Chen, TJ
;
Kao, JS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effects of N-2 annealing on the physical properties of room-temperature-deposited ion plating (IF) oxide have been characterized. As-deposited IP oxide exhibits higher refractive index and dielectric constant values than high-temperature-annealed IP oxide. Strained bonds existing in as-deposited oxide can be relaxed by N-2 annealing depending on the annealing temperature. After annealing at 800 degrees C, the physical characteristics of IP oxide are comparable to those of thermal oxide. (C) 1997 American Institute of Physics.
管管的法國梧桐不同
(1997-03-24)
管管
Physical characteristics of N-2 annealing on room-temperature-deposited ion plating oxide
(1997-03-24)
Yeh, CF
;
Chen, TJ
;
Kao, JS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effects of N-2 annealing on the physical properties of room-temperature-deposited ion plating (IF) oxide have been characterized. As-deposited IP oxide exhibits higher refractive index and dielectric constant values than high-temperature-annealed IP oxide. Strained bonds existing in as-deposited oxide can be relaxed by N-2 annealing depending on the annealing temperature. After annealing at 800 degrees C, the physical characteristics of IP oxide are comparable to those of thermal oxide. (C) 1997 American Institute of Physics.
管管的法國梧桐不同
(1997-03-24)
管管
管管的法國梧桐不同
(1997-03-24)
管管
管管的法國梧桐不同
(1997-03-24)
管管
Reflection-type normally-on two-wavelength modulator
(1997-03-27)
Tsai, CM
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The authors demonstrate a novel reflection-type normally-on two-wavelength modulator by combining two quantum-well structures with different operating wavelengths in a coupled cavity structure. Reflection spectra show simultaneous modulations at wavelengths of 856 and 886 nm in the device consisting of GaAs/A1GaAs and InGaAs/A1GaAs quantum wells for each wavelength. Under separate applied voltages, maximum reflectivity changes of 70 and 54% were obtained for the two wavelengths. To the best of the authors' knowledge, this is the First two-wavelength reflection modulator ever reported.
Development of a feedforward active noise control system by using the H-2 and H infinity model matching principle
(1997-03-27)
Bai, MR
;
Chen, HP
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
Two novel active noise control techniques on the basis of feedforward H-2 and H-infinity optimal model matching principle are proposed. These methods effectively overcome the problem of unstable inverse plant resulting from the inherent non-minimum phase property of the cancellation path. The proposed algorithms are implemented by using a digital signal processor. The experimental results obtained by using H-2 and H-infinity feedforward techniques show attenuation for stationary noise in a duct as comparable to those of conventional methods. The proposed methods also have potential in suppressing transient noises that have been the major difficulty in adaptive methods. Comparisons of the methods are summarized. (C) 1997 Academic Press Limited.
Development of a feedforward active noise control system by using the H-2 and H infinity model matching principle
(1997-03-27)
Bai, MR
;
Chen, HP
;
機械工程學系
;
Department of Mechanical Engineering
Two novel active noise control techniques on the basis of feedforward H-2 and H-infinity optimal model matching principle are proposed. These methods effectively overcome the problem of unstable inverse plant resulting from the inherent non-minimum phase property of the cancellation path. The proposed algorithms are implemented by using a digital signal processor. The experimental results obtained by using H-2 and H-infinity feedforward techniques show attenuation for stationary noise in a duct as comparable to those of conventional methods. The proposed methods also have potential in suppressing transient noises that have been the major difficulty in adaptive methods. Comparisons of the methods are summarized. (C) 1997 Academic Press Limited.
MOS magnetic current sensor based on standard CMOS process
(1997-03-27)
Yang, HM
;
Lei, TF
;
Huang, YC
;
Lee, CL
;
電子工程學系及電子研究所
A novel current sensor is proposed. The current sensor consists of one MOS magnetic sensor and a flat coil in an industrial CMOS process, An experimental device demonstrated a sensitivity of 8.4mV/A.
Reflection-type normally-on two-wavelength modulator
(1997-03-27)
Tsai, CM
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The authors demonstrate a novel reflection-type normally-on two-wavelength modulator by combining two quantum-well structures with different operating wavelengths in a coupled cavity structure. Reflection spectra show simultaneous modulations at wavelengths of 856 and 886 nm in the device consisting of GaAs/A1GaAs and InGaAs/A1GaAs quantum wells for each wavelength. Under separate applied voltages, maximum reflectivity changes of 70 and 54% were obtained for the two wavelengths. To the best of the authors' knowledge, this is the First two-wavelength reflection modulator ever reported.
MOS magnetic current sensor based on standard CMOS process
(1997-03-27)
Yang, HM
;
Lei, TF
;
Huang, YC
;
Lee, CL
;
電子工程學系及電子研究所
A novel current sensor is proposed. The current sensor consists of one MOS magnetic sensor and a flat coil in an industrial CMOS process, An experimental device demonstrated a sensitivity of 8.4mV/A.
Elastic interaction between screw dislocations and a circular surface crack
(1997-03-31)
Lin, KM
;
Lin, HC
;
Chen, KC
;
Chang, HL
;
材料科學與工程學系
The behaviour of a screw dislocation around a circular surface crack was analyzed using the conformal mapping method. The effects of the crack length l and its radius of curvature R on the shielding effect and the strain energy were discussed in detail. It was found that for a dislocation being fixed at a constant distance from the crack tip and located on a plane tangent to crack surface at the tip, there exists a critical crack length l* corresponding to a maximum shielding effect induced by the dislocation on the circular surface crack. The l* increases with R and approaches infinity as the crack becomes planar (i.e. R --> infinity). The shielding effect vanishes as the crack disappears. It increases rapidly with l if 0 < l much less than l*, regardless of R. After reaching the maximum, it decreases slightly for larger R but significantly for smaller R as the crack becomes longer. The shielding is more pronounced for larger R than that for smaller R, with the difference increasing with crack length. As a result, a surface microcrack propagates initially in a rather brittle manner then becomes more ductile. When the crack gets longer, it still keeps ductile for a less curved or a planar crack but becomes relatively brittle for a severely curved crack. In addition, the strain energy is also significantly influenced by crack length and increases rapidly with l when l is rather small, regardless of R. With increasing l, it becomes less affected by l, and the variation with R is still not obvious, with larger R corresponding to a slightly higher strain energy. (C) 1997 Elsevier Science S.A.
Elastic interaction between screw dislocations and a circular surface crack
(1997-03-31)
Lin, KM
;
Lin, HC
;
Chen, KC
;
Chang, HL
;
材料科學與工程學系
The behaviour of a screw dislocation around a circular surface crack was analyzed using the conformal mapping method. The effects of the crack length l and its radius of curvature R on the shielding effect and the strain energy were discussed in detail. It was found that for a dislocation being fixed at a constant distance from the crack tip and located on a plane tangent to crack surface at the tip, there exists a critical crack length l* corresponding to a maximum shielding effect induced by the dislocation on the circular surface crack. The l* increases with R and approaches infinity as the crack becomes planar (i.e. R --> infinity). The shielding effect vanishes as the crack disappears. It increases rapidly with l if 0 < l much less than l*, regardless of R. After reaching the maximum, it decreases slightly for larger R but significantly for smaller R as the crack becomes longer. The shielding is more pronounced for larger R than that for smaller R, with the difference increasing with crack length. As a result, a surface microcrack propagates initially in a rather brittle manner then becomes more ductile. When the crack gets longer, it still keeps ductile for a less curved or a planar crack but becomes relatively brittle for a severely curved crack. In addition, the strain energy is also significantly influenced by crack length and increases rapidly with l when l is rather small, regardless of R. With increasing l, it becomes less affected by l, and the variation with R is still not obvious, with larger R corresponding to a slightly higher strain energy. (C) 1997 Elsevier Science S.A.
VLSI cell placement on arbitrarily-shaped rectilinear regions using neural networks with calibration nodes - Comments
(1997-04-01)
Huang, KY
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
;
Department of Computer Science
D-stability bound analysis for discrete multiparameter singularly perturbed systems
(1997-04-01)
Hsiao, FH
;
Pan, ST
;
Teng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The D-stability (i.e., the stability in the sense that all the poles of a system are lying inside the disk D(alpha, r)) problem for discrete multiparameter singularly perturbed systems is considered in this brief, A two-stage method is first developed to analyze the stability relationship between the discrete multiparameter singularly perturbed systems and their corresponding reduced systems. An upper hound of the singular perturbation parameters is then derived such that the D-stability of the reduced systems implies that of the original systems, provided that the singular perturbation parameters are small enough to be within this bound. This fact enables us to investigate D-stability of the original systems by establishing that of their corresponding reduced systems.
Low-lying exciton states in a type-II broken-gap quantum well structure: A variation-basis-set approach
(1997-04-01)
Chu, CS
;
Chu, KD
;
電子物理學系
;
Department of Electrophysics
The exciton binding energy and the low-lying exciton states in a type-II broken-gap quantum well structure are studied. The conduction electron and the hole that form the exciton are spatially separated and are each confined by a quantum well. A variation-basis-set approach is proposed in which a set of variation basis set wavefunctions are constructed from the eigenstates of a variation Hamiltonian. The calculation of the exciton states can be carried out systematically and the accuracy of the state energies can be estimated. Numerical examples are presented, showing the rapid convergence of the excitonic levels with respect to the size of the variation basis set in and beyond the small well width regime. The effective binding energies for the states are found to increase with the decreasing of the well width. The low-lying exciton states in and beyond the small well width regime are presented.