Browsing by Issue Date, starting with "1999-11-28"

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Preparation and epoxy curing of p-nonylphenol/dicyclopentadiene adducts
(1999-11-28)
Tseng, FP
;
Chang, FC
;
Lin, SF
;
Lin, JJ
;
應用化學系
Phenol/dicyclopentadiene adducts were prepared from the BF3-catalyzed reaction of p-nonylphenol and dicyclopentadiene at molar ratios of 2 : 1 and 3 : 2. These dicyclopentadiene-derived novolac products contain tricyclodecane and multiple phenol functionalities. In curing with diglycidyl ether of bisphenol A, the polymer properties were compared with those cured with formaldehyde novolac or Jeffamine D-400 amine. When p-nonylphenol/dicyclopentadiene adducts were mixed with other commercially available curing agents such as Jeffamine D-400 amine, the tricyclodecane functionality was introduced into the resulting epoxy network. The flexibility of the cured resin was improved due to the presence of the tricyclodecane moiety in the polymer structure. (C) 1999 John Wiley & Sons, Inc.
摩耶精舍那隻孤鸞
(1999-11-29)
管管
Flow effect in the chiral-homeotropic liquid-crystal cell
(1999-11-29)
Chen, SH
;
Chen, LY
;
光電工程學系
;
Department of Photonics
We investigated the dynamics of the chiral-homeotropic liquid-crystal cell and found that the flow of liquid crystal causes an optical bounce after switching on a high applied voltage. We analyzed the behavior of the directors by computer simulation and found that the field-induced backflow effect results in the abnormal twist of the directors near the substrates. The abnormal twist slows down the rising speed of the chiral-homeotropic cell and produces an optical bounce during the rising period. Our results indicate that the backflow effect should be considered on the design of fast chiral-homeotropic liquid-crystal cells. The significant distinctions between this field-induced optical bounce and the well-known optical bounce of the twisted nematic liquid-crystal cell are also described in this letter. (C) 1999 American Institute of Physics. [S0003-6951(99)04148-0].
Effects of Mo-free C40Ti(Si1-xGex)(2) precursors and the thickness of an interposed Mo layer on the enhanced formation of C54Ti(Si1-xGex)(2)
(1999-11-29)
Luo, JS
;
Huang, JC
;
Lin, WT
;
Chang, CY
;
Shih, PS
The effects of Mo-free C40 Ti(Si1-xGex)(2) precursors and the thickness of an interposed Mo layer between Ti films and Si0.76Ge0.24 substrates on the lowering of formation temperature of C54 Ti(Si1-xGex)(2) were studied. Metastable C40 Ti(Si1-xGex)(2) precursors were grown by pulsed KrF laser annealing. Upon rapid thermal annealing, the Mo-free C40 phase could not be directly transformed to the C54 phase without going through the C49 phase. When the thickness of the interposed Mo layer increased, up to 2.5 nm, the temperature at which the C54 phase was initially formed changed from 750 to 600 and then to 650 degrees C. The present result showed that with increasing Mo concentration in the reacted layer, the phase stability shifted from C54 to C40 and no C49 was observed. It seems that apart from the C40 template mechanism, the electron/atom ratio also plays an important role in the enhanced formation of the C54 phase. (C) 1999 American Institute of Physics. [S0003-6951(99)02048-3].
A systematic approach for developing a foot size information system for shoe last design
(1999-11-29)
Cheng, FT
;
Perng, DB
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The property of a shoe last design significantly impacts the fitness of the shoes thus produced. Traditionally, a shoe last is designed by using numerous foot measure data. Among all the items of foot measure information, the foot length and joint girth are further identified as principle factors affecting shoe last design. In this paper, foot length and joint girth are analyzed by using a bi-variate normal distribution to obtain a more efficient foot size grading system. A set of 2486 adult male samples collected in Taiwan area are used in this analysis to establish the norm for the foot length and joint girth. A foot size information system (FSIS) providing shoe last related information such as the percentage of population that a last can fit in is established from the analysis results. This study contributes designers the grading information that is helpful for shoe last design. Relevance to industry Shoe last design is the basis for footwear design. The foot size information system derived in this paper provides shoe making industry with a more efficient and economical size grading system to design shoe lasts. This grading system also promotes customer satisfaction with better fitness in foot size. (C) 1999 Elsevier Science B.V. All rights reserved.
A polynomial time algorithm for shaped partition problems
(1999-11-29)
Hwang, FK
;
Onn, S
;
Rothblum, UG
;
應用數學系
;
Department of Applied Mathematics
We consider the class of shaped partition problems of partitioning n given vectors in d-dimensional criteria space into p parts so as to maximize an arbitrary objective function which is convex on the sum of vectors in each part, subject to arbitrary constraints on the number of elements in each part. This class has broad expressive power and captures NP-hard problems even if either d or p is fixed. In contrast, we show that when both d and p are fixed, the problem can be solved in strongly polynomial time. Our solution method relies on studying the corresponding class of shaped partition polytopes. Such polytopes may have exponentially many vertices and facets even when one of d or p is fixed; however, we show that when both d and p are fixed, the number of vertices of any shaped partition polytope is O(n(d(p2))) and all vertices can be produced in strongly polynomial time.
Authentication protocols for the broadband ISDN billing system
(1999-12-01)
Lo, CC
;
Yeh, YC
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
The broadband integrated services digital network (B-ISDN) offers a wide variety of services to its customers. From both provider's and user's perspective, a fair and flexible billing system is indispensable to the operation of B-ISDN. In this paper, we discuss different billing policies, and their corresponding authentication protocols, which can be used by the B-ISDN billing system. Flat rate and usage-based rate are two most frequently used billing policies. Because of the diversity of B-ISDN services, combining these two billing policies, along with priority pricing, is a feasible scheme for designing a B-ISDN billing system. The membership authentication protocol (MAP) and the personal authentication protocol (PAP) are proposed to support the authentication requirements of the flat rate and usage-based rate billing policies, respectively. The MAP applies the cipher block chaining (CBC) encryption in the two-party authentication protocol, while the PAP is a modified version of the station-to-station (STS) authentication protocol. Both protocols are designed in conjunction with a suggested key management method. Cryptanalysis shows that both the MAP and the PAP are very secure. Simulation results indicate that both protocols are efficient for providing mutual authentication. Together, these two protocols provide a good authentication mechanism to the B-ISDN billing system. (C) 1999 Elsevier Science B.V. All rights reserved.
Stability analysis and bounded sliding-mode control of a class of multi-input bilinear systems
(1999-12-01)
Chen, YP
;
Chang, JL
;
Lai, KM
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A bounded sliding-mode controller is developed for a class of multi-input bilinear systems. The sliding vector design is based on the conventional pole-assignment method for linear time-invariant systems. Three conditions are required for the assigned eigenvalues when applying the pole-assignment method. A potential reaching-and-sliding region and a stable sliding region are determined around the origin, which is shown to be locally asymptotically stable. Numeric simulation results are used to demonstrate the success of the proposed bounded sliding-mode controller.
A genetic algorithm for the optimal design of microwave filters
(1999-12-01)
Hsu, HM
;
Tsai, SP
;
Wu, MC
;
Tzuang, CK
;
電信工程研究所
This paper presents a multiple objective genetic algorithm for determining the component parameters in the design of a microwave filter. In this approach, we first propose a set of fuzzy-based membership functions for modeling the five design specifications (objective functions) of the microwave filter design problem. The five objective functions are then aggregated into a single-valued fitness function. Finally, a set of near-optimal component parameters for the microwave filter can be found by applying the proposed genetic algorithm. A large number of experiments were performed and demonstrated satisfactory results. This approach has three principal merits. First, it counteracts entrapment in a local optimal solution. Second, the processing of multiple objectives is relatively easy. Third, the generated solution is independent of the initial estimate. Significance: This paper presents a multiple objective genetic algorithm for determining the component parameters in the design of a microwave filter.
On a problem of Dynkin
(1999-12-01)
Sheu, YC
;
應用數學系
;
Department of Applied Mathematics
Consider an (L, alpha)-superdiffusion X on R-d, where L is an uniformly elliptic differential operator in R-d, and 1 < alpha less than or equal to 2. The G-polar sets for X are subsets of R x R-d which have no intersection with the graph G of X, and they are related to the removable singularities for a corresponding nonlinear parabolic partial differential equation. Dynkin characterized the G-polarity of a general analytic set A subset of R x R-d in term of the Bessel capacity of A, and Sheu in term of the restricted Hausdorff dimension. In this paper we study in particular the G-polarity of sets of the form E x F, where E and F are two Borel subsets of R and R-d respectively. We establish a relationship between the restricted Hausdorff dimension of E x F and the usual Hausdorff dimensions of E and F. As an application, we obtain a criterion for G-polarity of E x F in terms of the Hausdorff dimensions of E and F, which also gives an answer to a problem proposed by Dynkin in the 1991 Wald Memorial Lectures.
管管作品六首
(1999-12-01)
管管
Embedding of any type of data in images based on a human visual model and multiple-based number conversion
(1999-12-01)
Wu, DC
;
Tsai, WH
;
資訊工程學系
;
Department of Computer Science
A novel approach to embedding any type of digital data into a cover image is proposed, which utilizes a human visual model to guarantee that the modification of the cover image is imperceptible. A quantized contrast function based on the model is constructed first. The gray values of each 3 x 3 sub-image of the cover image are used to compute, using the function, a range of gray levels with the same contrast as that of the central pixel of the sub-image. The embedding process proceeds by replacing the gray value of the central pixel by one of the values in the range. This guarantees that the changes be imperceptible. The data to be embedded is treated as a binary stream and is partitioned into a number of sub-streams. A multiple-base number conversion mechanism is used to convert each sub-stream of data into values which are then embedded in the central pixels of sub-images. The embedded data can be extracted out from the resulting stego-image without referencing the original image. Experimental results show that the proposed method is feasible. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
管管作品六首
(1999-12-01)
管管
The block-based cycle time estimation algorithm for wafer fabrication factories
(1999-12-01)
Chung, SH
;
Huang, HW
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Cycle time is both an important performance measure and requisite input data for performing production planning. However, the interactive effects between some factors such as process complexity and variety of workstations, leads to difficulty in estimating cycle time. To solve these problems, this study developed a block-based cycle time estimation algorithm, called BBCT, to estimate the total cycle time for each kind of wafer process. Process was divided into numerous blocks. The block cycle time is induced by batch and loading issues. The BBCT algorithm is used to derive the cycle time induced by the batch issue according to the process characteristics within each block. A queuing time model is used to derive the waiting time resulting from the loading issue. The simulation results show that the cycle time estimation performance is much improved by the BBCT algorithm. Significance: The proposed BBCT algorithm can improve the performance of cycle time estimation, and served as the basis for setting production targets.
New techniques on deformed image motion estimation and compensation
(1999-12-01)
Lin, CT
;
Wu, GD
;
Hsiao, SC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, new techniques for deformed image motion estimation and compensation using variable-size block-matching are proposed, which can be applied to an image sequence compression system or a moving object recognition system. The motion estimation and compensation techniques have been successfully applied in the area of image sequence coding. Many research papers on improving the performance of these techniques have been published; many directions are proposed, which can all lead to better performance than the conventional techniques. Among them, both generalized block-matching and variable-size block-matching are successfully applied in reducing the data rate of compensation error and motion information, respectively. These two algorithms have their merits, but suffer from their drawbacks. Moreover, reducing the data rate in compensation error is sometimes increasing the data rate in motion information, or vice versa, Based on these two algorithms, we propose and examine several algorithms which are effective in reducing the data rate. We then incorporate these algorithms into a system, in which they work together to overcome the disadvantages of individual and keep their merits at the same time, The proposed system can optimally balance the amount of data rate in tno aspects (i.e., compensation error and motion information), Experimental results show that the proposed system outweighs the conventional techniques. Since we propose a recovery operation which tries to recover the incorrect motion vectors from the global motion, this proposed system can also be applied for the moving object recognition in image sequence.
True near-field optical characters of a GaAlAs semiconductor laser diode
(1999-12-01)
Chen, SH
;
Tsai, DP
;
Chen, YF
;
Ong, PM
;
電子物理學系
In this research we have taken advantage of near-field scanning optical microscopy, a recently developed technique, to test the optical nature of GaAlAs semiconductor laser diodes working at 780 nm. With this method, both the images of the topographic and the near-field intensity of the laser diodes can be simultaneously obtained. With the obtained results, we can analyze the variety of the geometric structure, the local near-field optical intensity, the propagating modes, and the near-field mode-field diameter at different working states of the laser diodes. Hereby, we can find the factors that affected the radiation cavity of the laser diode and explore its alive state. (C) 1999 American Institute of Physics. [S0034-6748(99)01112-0].
管管作品六首
(1999-12-01)
管管
Non-reinitialized fully distributed power control algorithm
(1999-12-01)
Wang, JT
;
Lee, TH
;
電信工程研究所
;
Institute of Communications Engineering
A fully distributed power control (FDPC) algorithm has been recently proposed for cellular mobile systems. In the algorithm, the connection which has the smallest initial carrier-to-interference (CIR) ratio is removed if CIR requirements are not satisfied after L iterations of power control, The transmitter power levels of surviving connections are then reset to the maximal allowed values and the algorithm is executed again. We prove in this paper that, if the transmitter power levels are not reset after a connection is removed, then a feasible power set can be found faster and the power levels employed are smaller.
Kinetic study on epoxy bisphenol-A diacrylate IPN formation
(1999-12-01)
Lin, MS
;
Wang, MW
;
應用化學系
;
Department of Applied Chemistry
Interpenetrating polymer networks (IPN) based on diglycidyl ether of bisphenol-A (DGEBA) and bishenol-A diacrylate (BADA) in weight ratios of 100/0, 50/50, and 0/100 were blended and were cured simultaneously by using benzoyl peroxide (BPO) and 4,4'-methylenedianiline (MDA) as curing agents. Kinetic study during IPN formation was carried out at 65, 70, 75 and 80 degrees C. Absorbance changes at 1623.3 cm(-1) and 914 cm(-1) relating to concentration changes of C=C and epoxide were monitored with Fourier-transform infrared spectroscopy (FTIR). The epoxide cure kinetic data revealed a combination of non-catalytic bimolecular reaction and a catalyzed termolecular reaction, while the C=C cure kinetic data fitted a first-order reaction. The calculated kinetic parameters indicated decreased rate constants and increased activation energies of the IPN compared with those of the individual components. Presumably, chain entanglements between the two networks provide a sterically hindered environment for the cure reactions and vitrification restrains the chain mobility, accounting for the kinetic parameters. (C) 1999 Society of Chemical Industry.
Variations of X-ray spectrum in total reflection X-ray fluorescence (TXRF) analysis with respect to Si wafer crystal orientation for different incident angles
(1999-12-01)
Liou, BW
;
Lee, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work studies the W-L-beta, Si-K-alpha and spurious radiations, which occur in the total reflection X-ray fluorescence (TXRF) analysis technique, Measurements at different azimuth angles were studied with respect to; the wafer orientation under different incident glancing angles of the X-ray beam on the surface of a bare Si-wafer, an oxide film, and an amorphous silicon film. It was found that both the W-LB radiation and the spurious radiation signals have a four fold periodic;variation with respect to the wafer orientation while the Si-K-alpha radiation signal does not have such a variation. For the oxide wafers, this periodic variation for the W-L-beta radiation and the spurious radiation signals becomes less and eventually disappears as the thickness of the oxide increases to 42 nm. For the amorphous silicon wafer, the above periodic variation phenomenon does not exist. This reveals that the W-L-beta and the:spurious radiation signals are mainly due to the interaction of incident X-ray evanescent radiation with the silicon crystal lattice. To reduce spurious signals in the TXRF analysis, a measurement at azimuth angle along the [100] directions of 45, 135, 225 or 315 degrees to the oxide-covered surface is suggested.