Browsing by Issue Date, starting with "1996-11-07"

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Effect of temperature on fracture toughness of PC/ABS based on J-integral and hysteresis energy methods
(1996-11-07)
Lu, ML
;
Chiou, KC
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
The critical fracture toughness J(1c) of the polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend at different temperatures was obtained from ASTM E813-81, E813-87, and the recently developed hysteresis energy methods, respectively. The J(1c) value increases with increase of the test temperature ranging from -60 to 70 degrees C. The hysteresis energy method and the ASTM E813-81 method result in comparable J(1c) values, while the ASTM E813-87 results in about 80-110% higher values. The critical initiation displacements determined from the plots of hysteresis energy and the true crack growth length vs. crosshead displacement are very close. This indicates that the critical initiation displacement deter mined by the hysteresis method is indeed the displacement at the onset of true crack initiation and the corresponding J(1c) represents a physical event of crack initiation. The fracture toughness, K-1c value, based on linear elastic fracture mechanics (LEFM), was determined by using K-Q analysis (ASTM E399-78), and the obtained K-Q value decreases with the increase of the test temperature. The K-Q value is not the real LEFM K-1c value because the criterion of P-max/P-Q < 1.1 has not been satisfied. However, the corresponding J(Q) obtained from the K-Q analysis is comparable to the J(1c) obtained from the E813-81 method at lower temperature (-45 or -60 degrees C), an indication of LEFM behavior at lower temperature. The various schemes and size criterion based on LEFM and the J-method are explored for the validity of J(1c) and K-1c values. (C) 1996 John Wiley & Sons, Inc.
Optimum gain-equalised configuration of wideband erbium-doped fibre amplifier using inter-stage samarium-doped fibre and midway isolator
(1996-11-07)
Chen, YK
;
Liaw, SK
;
光電工程學系
;
Department of Photonics
The optimum gain-equalised configuration for the erbium-doped fibre amplifier (EDFA) using a samarium-doped fibre (SDF) is investigated. The dual-pumping scheme with inter-stage SDF and midway isolator was found to be the optimum scheme for obtaining flattened high spectral gain with variation of less than or equal to +/-0.7dB and with a low noise figure of less than or equal to 5.6dB within the 1530-1560nm range. This amplifier is suitable for multiwavelength transmission systems containing EDFA cascades.
Effect of temperature on fracture toughness of PC/ABS based on J-integral and hysteresis energy methods
(1996-11-07)
Lu, ML
;
Chiou, KC
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
The critical fracture toughness J(1c) of the polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend at different temperatures was obtained from ASTM E813-81, E813-87, and the recently developed hysteresis energy methods, respectively. The J(1c) value increases with increase of the test temperature ranging from -60 to 70 degrees C. The hysteresis energy method and the ASTM E813-81 method result in comparable J(1c) values, while the ASTM E813-87 results in about 80-110% higher values. The critical initiation displacements determined from the plots of hysteresis energy and the true crack growth length vs. crosshead displacement are very close. This indicates that the critical initiation displacement deter mined by the hysteresis method is indeed the displacement at the onset of true crack initiation and the corresponding J(1c) represents a physical event of crack initiation. The fracture toughness, K-1c value, based on linear elastic fracture mechanics (LEFM), was determined by using K-Q analysis (ASTM E399-78), and the obtained K-Q value decreases with the increase of the test temperature. The K-Q value is not the real LEFM K-1c value because the criterion of P-max/P-Q < 1.1 has not been satisfied. However, the corresponding J(Q) obtained from the K-Q analysis is comparable to the J(1c) obtained from the E813-81 method at lower temperature (-45 or -60 degrees C), an indication of LEFM behavior at lower temperature. The various schemes and size criterion based on LEFM and the J-method are explored for the validity of J(1c) and K-1c values. (C) 1996 John Wiley & Sons, Inc.
A periodic review inventory system with two supply modes
(1996-11-08)
Chiang, C
;
Gutierrez, GJ
;
管理科學系
;
Department of Management Science
We describe a periodic review inventory system in which there are two modes of resupply, namely a regular mode and an emergency mode. Orders placed through the emergency channel have a shorter supply lead time but are subject to higher ordering costs compared to orders placed through the regular channel. We analyze this problem within the framework of an order-up-to-R inventory control policy. At each review epoch, the inventory manager must decide which of the two supply modes to use and then order enough units to raise the inventory position to a level R. We show that given any non-negative order-up-to level, either only the regular supply mode is used, or there exists an indifference inventory level such that if the inventory position at the review epoch is below the indifference inventory level, the emergency supply mode is used. We also develop procedures for solving for the two policy parameters, i.e., the order-up-to level and the indifference inventory level.
A periodic review inventory system with two supply modes
(1996-11-08)
Chiang, C
;
Gutierrez, GJ
;
管理科學系
;
Department of Management Science
We describe a periodic review inventory system in which there are two modes of resupply, namely a regular mode and an emergency mode. Orders placed through the emergency channel have a shorter supply lead time but are subject to higher ordering costs compared to orders placed through the regular channel. We analyze this problem within the framework of an order-up-to-R inventory control policy. At each review epoch, the inventory manager must decide which of the two supply modes to use and then order enough units to raise the inventory position to a level R. We show that given any non-negative order-up-to level, either only the regular supply mode is used, or there exists an indifference inventory level such that if the inventory position at the review epoch is below the indifference inventory level, the emergency supply mode is used. We also develop procedures for solving for the two policy parameters, i.e., the order-up-to level and the indifference inventory level.
Topological properties of hierarchical cubic networks
(1996-11-10)
Chiang, WK
;
Chen, RJ
;
資訊工程學系
;
Department of Computer Science
The hierarchical cubic network (HCN), which takes hypercubes as basic clusters, was first introduced in [6]. Compared with the hypercube of the same size, the HCN requires only about half the number of links and provides a lower diameter. This paper first proposes a shortest-path routing algorithm and an optimal broadcasting algorithm for the HCN. We then show that the HCN is optimal fault tolerant by constructing node-disjoint paths between any two nodes, and demonstrate that the HCN is Hamiltonian. Moreover, it is shown that the average dilation for hypercube emulation on the HCN is bounded by 2. This result guarantees that all the algorithms designed for the hypercube can be executed on the HCN with a small degradation in time performance.
Helicobacter pylori induces gene expression in human gastric cells identified by mRNA differential display
(1996-11-12)
Wong, L
;
Lue, MY
;
Chang, CA
;
Lin, YL
;
Chan, EC
Changes in gene expression patterns in gastric cells infected with Helicobacter pylori were characterized by means of mRNA differential display. Total RNA preparations were extracted from the H. pylori infected gastric cells and paired non-infected cells, and were probed with candidate clones identified after screening up to 6,000 mRNA species. Among them, four clones, 04G-1, 04G-2, 01G-1, and Cppa-2 show significant expression in the infected cells by Northern blot analysis, and they are 199 bp, 196 bp, 228 bp, and 276 bp in length, respectively. Database search revealed that nucleotide sequences of these clones share very low identity with any known sequence. These results indicate that H. pylori can significantly affect gene expression in gastric cells. Furthermore mRNA differential display can be used in pathogenesis studies to identify new genes in gastric cells in response to insults such as H. pylori. (C) 1996 Academic Press, Inc.
Helicobacter pylori induces gene expression in human gastric cells identified by mRNA differential display
(1996-11-12)
Wong, L
;
Lue, MY
;
Chang, CA
;
Lin, YL
;
Chan, EC
Changes in gene expression patterns in gastric cells infected with Helicobacter pylori were characterized by means of mRNA differential display. Total RNA preparations were extracted from the H. pylori infected gastric cells and paired non-infected cells, and were probed with candidate clones identified after screening up to 6,000 mRNA species. Among them, four clones, 04G-1, 04G-2, 01G-1, and Cppa-2 show significant expression in the infected cells by Northern blot analysis, and they are 199 bp, 196 bp, 228 bp, and 276 bp in length, respectively. Database search revealed that nucleotide sequences of these clones share very low identity with any known sequence. These results indicate that H. pylori can significantly affect gene expression in gastric cells. Furthermore mRNA differential display can be used in pathogenesis studies to identify new genes in gastric cells in response to insults such as H. pylori. (C) 1996 Academic Press, Inc.
Band-diagonal operators
(1996-11-15)
Fong, CK
;
Wu, PY
;
應用數學系
;
Department of Applied Mathematics
We show that there are operators on a five-dimensional Hilbert space which are not tridiagonal, and that there are compact operators and normal operators on separable infinite-dimensional spaces which are not band-diagonal.
Numerical microcanonical ensemble method for calculation on statistical models with large lattice sizes
(1996-11-15)
Wang, JZ
;
Yang, TJ
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
Based on the microcanonical ensemble theory in statistical mechanics, we devise a method that can be used to enhance the capability of numerical calculation on statistical models with large lattice sizes. In our method, we take the expectation value of the energy, as defined in quantum mechanics, instead of the eigenvalue as the energy of a physical system. We show mathematically that the relevant physical quantities obtained in this way are unchanged in the thermodynamical limit and we apply this method to numerical calculations. In this paper, we present our numerical results with the one-dimensional spinless fermionic model as a first test of our method. The numerical calculations are done to a 4096 lattice size using a computer with a speed of about 40 mflops. Our numerical data agree quite well with the exact values. Also, the fluctuation of data is small, in contrast to that obtained using the quantum Monte Carlo method.
Numerical microcanonical ensemble method for calculation on statistical models with large lattice sizes
(1996-11-15)
Wang, JZ
;
Yang, TJ
;
電子物理學系
;
Department of Electrophysics
Based on the microcanonical ensemble theory in statistical mechanics, we devise a method that can be used to enhance the capability of numerical calculation on statistical models with large lattice sizes. In our method, we take the expectation value of the energy, as defined in quantum mechanics, instead of the eigenvalue as the energy of a physical system. We show mathematically that the relevant physical quantities obtained in this way are unchanged in the thermodynamical limit and we apply this method to numerical calculations. In this paper, we present our numerical results with the one-dimensional spinless fermionic model as a first test of our method. The numerical calculations are done to a 4096 lattice size using a computer with a speed of about 40 mflops. Our numerical data agree quite well with the exact values. Also, the fluctuation of data is small, in contrast to that obtained using the quantum Monte Carlo method.
Structure of high resistivity GaAs film grown by low-temperature metalorganic chemical vapor deposition
(1996-11-18)
Chen, WC
;
Chang, CS
;
Chan, SH
;
光電工程學系
;
Department of Photonics
The structure of a low-temperature GaAs layer grown by low-pressure metalorganic chemical vapor deposition with precursors of triethylgallium and arsine is reported. Dense particles containing Ga clusters are found in a high resistivity GaAs film grown at 420 degrees C, The size and concentration of particles are about 800-1000 nm and 7X10(11) cm(-3), respectively. (C) 1996 American Institute of Physics.
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