Browsing by Issue Date, starting with "2002-02-15"

Now showing 1 - 20 of 74902

High-performance IP routing table lookup
(2002-02-15)
Wang, PC
;
Chan, CT
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
Nowadays, the commonly used table lookup scheme for IP routing is based on the so-called classless interdomain routing (CIDR). With CIDR, routers must find out the best matching prefix (BMP) for IP packets forwarding, which complicates the IP lookup. Currently, this process is mainly done in software and several schemes have been proposed for hardware implementation. Since the IP lookup performance is a major design issue for the stew generation routers, in this article we propose a fast IP address lookup scheme, which significantly reduces the forwarding table to fit into SRAM with very low cost. It can also be implemented in hardware using the pipeline technique. By using our proposed method, the required memory space can be 90-170 Kb less than the previous scheme and three memory accesses for a lookup in the worst case. When implemented in hardware pipeline architecture, our mechanism can achieve one routing lookup per memory access. (C) 2002 Elsevier Science B.V. All rights reserved.
High-temperature healing of interfacial voids in GaAs wafer bonding
(2002-02-15)
Wu, YCS
;
Liu, PC
;
Feigelson, RS
;
Route, RK
;
材料科學與工程學系
Artificial voids were introduced at bonding interfaces to study how processing parameters affected the healing mechanism of interfacial voids in GaAs wafer bonding. These voids were created by placing unpatterned wafers in contact with topographically patterned wafers. During the bonding process, crystallites formed within these voids and corresponded to bonded regions within the voids. Their formation depended strongly on the height of the surface irregularities at the wafer interfaces. When the void depth (h) was greater than or equal to200 nm, most of the crystallites were diamond shaped. The edges of the diamond features were elongated in the <100> direction. On the other hand, when the void depth was small (hless than or equal to70 nm), dendrites grew quickly in the <110> direction. (C) 2002 American Institute of Physics.
Group testing and fault detection for replicated files
(2002-02-15)
Hwang, FK
;
Zang, WN
;
應用數學系
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Department of Applied Mathematics
A file in a distributed database system is replicated on M sites and may contain corrupted pages. The purpose of this paper is to apply a group testing technique to detect corrupted pages in these replicated files. Our detection scheme, based on the structure of the Reed-Solomon code as proposed by Abdel-Ghaffar and El Abbadi, is optimal for M greater than or equal to 4 and has performance guarantee of (7)-(6) for M = 3. (C) 2002 Elsevier Science B.V. All rights reserved.
Using fuzzy measures and habitual domains to analyze the public attitude and apply to the gas taxi policy
(2002-02-16)
Chen, TY
;
Chang, HL
;
Tzeng, GH
;
運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
Public acceptance and support are the crucial keys for implementing public policies successfully. Thus, the understanding of public acceptance or rejection towards the policy, as well as the important attributes of concern, could be very helpful to implementing the policy. However, most conventional attitude models could not approximate people's subjective evaluation process exactly by virtue of the additivity and independence assumptions. Additionally, people's decision behavior is deeply affected by their existing habits. Since habitual domains exist in the decision process, if the government can change or extend people's habitual thinking in favor of the public policy, the policy will receive satisfactory acceptance. Therefore, this study uses the habitual domain theory to analyze the public's attitude towards public policies. Furthermore, general fuzzy measures and fuzzy integrals, which require only boundary conditions and monotonicity, are also applied to develop a public attitude analysis model. An empirical study on the compress natural gas (CNG) taxi policy in Taipei City is conducted to show the applicability of the proposed model. The empirical results indicate that there are significant differences between the public's concern and governmental publicity, and some valuable strategies are suggested to the government. (C) 2002 Elsevier Science B.V. All rights reserved.
Electrical and structural characteristics of PbTiO3 thin films with ultra-thin Al2O3 buffer layers
(2002-02-17)
Sun, CL
;
Chen, SY
;
Yang, MY
;
Chin, A
;
材料科學與工程學系
Polycrystalline PbTiO3 thin films have been prepared on Si substrates with ultra-thin SiO2 and Al2O3 buffer layers by chemical solution deposition, respectively. Although capacitance-voltage characteristics show hysteresis loops in both cases, the memory window of PbTiO3/Al2O3 stacked dielectric is 3.3V larger than that on SiO2. In addition, well-behaved capacitance-voltage characteristics are only obtained in PbTiO3/Al(2)o(3) and the PbTiO3 films on Al2O3 have the dielectric constant of 116 larger than 42 of PbTiO3 films on SiO2. The leakage current density of PbTiO3/Al2O3 dielectric is 1.3 x 10(-7) A cm(-2) at -2.5 V, which is low enough for deep sub-mum application. (C) 2002 Elsevier Science B.V. All rights reserved.
Phase transformations in a Cu-142Al-15.0Ni alloy
(2002-02-17)
Chen, CH
;
Liu, TF
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In the as-quenched condition, the microstructure of the Cu-14.2Al-15.0Ni alloy was D0(3) phase containing extremely fine L-J precipitates. Since both fine D0(3) domains with a/2(100) anti-phase boundaries (APBs) and small B2 domains with a/4(111) APBs could be observed, the D0(3) phase existing in the as-quenched alloy should be formed by an A2 --> B2 --> D0(3) continuous ordering transition during quenching. It is worthwhile to note that the a/4(111) APBs have never been observed by other workers in the Cu-Al-Ni ternary alloys before. When the as-quenched alloy was aged at temperatures ranging from 400 to 1000 degreesC for longer times, the phase transformation sequence as the aging temperature increased was found to be (alpha + B2 precipitate) --> (B2 + B2 precipitate) --> B2 --> A2. This transformation has also never been observed by other workers in the Cu-Al-Ni ternary alloys before. (C) 2002 Elsevier Science B.V. All rights reserved.
Characterization of BaPbO3 and Ba(Pb1-xBix)O-3 thin films
(2002-02-17)
Sun, CL
;
Wang, HW
;
Chang, MC
;
Lin, MS
;
Chen, SY
BaPbO3 and Ba(Pb1-xBix)O-3 films made from barium 2-ethylhexanoate, lead 2-ethylhexanoate and bismuth acetate were prepared by metal-organic deposition (MOD) method on Pt/Ti/SiO2/Si substrate. The phase transition and the physical properties of these films were studied. The polycrystalline BaPbO3 phase starts to form above 600 degreesC and the Pb-excess addition would enhance the formation of single perovskite BaPbO3 phase. With increasing annealing temperature, the optimum sheet resistance 1.6 Omega sq(-1) (resistivity approximate to 1.07 x 10(-4) Omega cm) could be obtained at 750 degreesC. However, an annealing temperature over 800 degreesC causes reactions between substrate and BaPbO3 phase and results in sharp increase of resistance. On the other hand, the substitution of Pb by Bi in the Ba(Pb1-xBix)O-3 films could stabilize the perovskite phase, though the sheet resistance is raised over 10 Omega sq(-1) at x = 0.3. (C) 2002 Elsevier Science B.V. All rights reserved.
最短篇名家展
(2002-02-21)
管管
無線傳輸系統
(2002-02-21)
張瑞川
;
黃良益
;
姜美玲
一種整合Access Point間通信技術與移動式IP技術而成的無線傳輸系統，用來解決移動主機在相同子網域內不同的BSS之間handoff的問題，並使移動主機也能在不同的手網域中任意的移動。本發明利用特殊之設計，以減少不必要或多餘的資料傳輸，以在無線的網路環境有限傳輸頻寬下，提供更有效率的資料傳輸。實驗結果證明了移動主機除了能在不同網域中任意漫遊外，同時也能在相同的網域中任意移動，且順利的進行資料傳輸。
Effects of CH4/SiH4 flow ratio and microwave power on the growth of beta-SiC on Si by ECR-CVD using CH4/SiH4/Ar at 200 degrees C
(2002-02-22)
Lee, WH
;
Lin, JC
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Lee, C
;
Cheng, HC
;
Yew, TR
The effects of CH4/SiH4 flow ratio and microwave power on the formation of SiC at 200 degreesC by electron cyclotron resonance chemical vapor deposition is investigated. When the CH4/SiH4 flow ratio is varied from 0.5 to 10, crystalline phase of films vary from polycrystalline silicon to polycrystalline P-SiC and finally to amorphous silicon carbide. However, as the microwave power increases from 300 to 1500 W. the film microstructure changes from polycrystalline Si to amorphous SiC. and finally to polycrystalline beta-SiC. The deposition mechanism which controls the film characteristics is also presented. (C) 2002 Elsevier Science B.V. All rights reserved.
Anisotropic diffraction of light by volume holographic grating in birefringent photorefractive crystals with extended wavelength range
(2002-02-25)
Zaitsev, AK
;
Hsu, KY
;
Lin, SH
;
交大名義發表
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National Chiao Tung University
The properties of anisotropic diffraction of light by volume holographic grating in birefringent photorefractive crystals are discussed. This diffraction takes place when the refractive index for diffracted light is different from the refractive index for incident light. It is found that in some special geometry of wavevector diagram the diffraction becomes less sensitive to the wavelength mismatch of Bragg condition. The wavelength range may extent in several times the range of ordinary isotropic diffraction on the grating of the same spacing and thickness. Theoretical explanation of this phenomena and experimental results of widerange diffraction in BaTiO3 photorefractive crystal are also presented. (C) 2002 Optical Society of America.
Identification of the general acid/base catalyst of a family 3 beta-glucosidase from Flavobacterium meningosepticum
(2002-02-26)
Li, YK
;
Chir, J
;
Tanaka, S
;
Chen, FY
;
應用化學系
beta-Glucosidase from Flavobacterium meningosepticum (Fbgl) (also known as Chryseobacterium meningosepticum) has been classified as a member of the family 3 glycohydrolases. It is a retaining enzyme involving a two-step, double-displacement mechanism. 0247 was shown to function as the nucleophile of the enzymatic reaction [Li, Y.-K., Chir, J., and Chen, F.-Y. (2001) Biochem. J. 355, 835-840]. However, the general acid/base catalyst of this enzyme and of all other family 3 glycohydrolases has not yet been identified. On the basis of amino acid sequence alignment of 15 family 3 enzymes, 11 residues (071, 8129, E132, E136, D137, K168, H169, E177, D247, D458, and E473) are highly conserved. All of these residues are studied by site-directed mutagenesis and kinetic investigation. Analyzing the catalytic power of all mutants reveals E473 residue is the best candidate of the acid/base catalyst. Detailed studies supporting this suggestion are summarized as follows. (1) The k(cat) and K-m values for the hydrolysis of 2,4-dinitrophenyl beta-D-glucopyranoside (2,4-DNPG) by E473G are reduced 3300- and 900-fold, respectively, compared with those of the wild type (WT). (2) The k(cat) values of E473G-catalyzed hydrolysis are virtually invariant with pH over the range of 5.0-9.0. (3) The activity of E473G with 2,4-DNPG is enhanced by the addition of azide, and beta-glucosyl azide is formed. (4) The k(cat) of the reaction of 2-carboxyphenyl beta-glucoside catalyzed by E473G is comparable to that for hydrolysis by wild-type Fbgl and is 100- and 320-fold better than the k(cat) values for the E473G-catalyzed hydrolysis of 4-carboxyphenyl beta-glucoside and the corresponding methyl ester, respectively. (5) The accumulated glucosyl-enzyme intermediate was directly observed by mass analysis in the reaction of 2,4-DNPG with E473G. All of these results confirm that E473 is the general acid/base catalyst of Fbgl.
A study on seamless tube in the planetary rolling process
(2002-02-28)
Shih, CK
;
Hsu, RQ
;
Hung, CH
;
機械工程學系
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Department of Mechanical Engineering
In this paper, the finite element method and the dual-stream functions upper bound method are selected to analyze the tube rolling process with a planetary rolling mill. Three-dimensional elastic-plastic finite element simulations with special emphasis on the determination of the roller profile and realistic contact conditions between the rollers, workpiece and mandrel are used to reveal the deformation characteristics of seamless tube during the rolling process. In addition, the kinematically admissible velocity field of the deforming tube is described in terms of two stream functions so that the velocity components of the deforming tube can be obtained through the upper bound analysis. In both analysis methods, the equation of meshing is used to determine the contact condition between the rollers and the workpiece. The results from both methods with different variables are observed and compared. (C) 2002 Elsevier Science B.V. All rights reserved.
Polarized blue emission based on a side chain liquid crystalline polyacrylate containing bis-tolane side groups
(2002-03-01)
Chang, SW
;
Li, AK
;
Liao, CW
;
Hsu, CS
;
應用化學系
A novel side chain liquid crystalline (LC) polyacrylate (1P) containing highly conjugated bis-tolane side groups was synthesized and used for polymer light emitting diodes application. Polymer 1P shows a nematic phase at room temperature. It exhibits a UV absorption peak at 330 run and emits a blue light at 425 inn. Polyimide (PI), polyaniline (PA) and poly(3,4-diethylenedioxythiophene) (PEDOT) were used as alignment materials for polymer 1P. The photoluminescence dichroic ratios of 1P on rubbed PI, PA and PEDOT films are 10.4, 8.3 and 7.3, respectively. The electroluminescence dichroic ratio of IP aligned on a PEDOT film is 6.1.
Effective strategy for porous organosilicate to suppress oxygen ashing damage
(2002-03-01)
Liu, PT
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Chang, TC
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Mor, YS
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Chen, CW
;
Tsai, TM
Photoresist stripping with oxygen plasma ashing destroys numerous functional groups in porous organosilicate glasses (OSGs), This impact makes the porous OSG relatively hydrophilic and causes low-k dielectric degradation, To mitigate these issues, various strategies are investigated to enhance oxygen plasma resistance of the porous OSG. These include physical and chemical procedures. Both structural and electrical analyses are used to determine their efficiency. In addition, an optimum prescription that consists of H, plasma and chemical trimethylchlorosilane treatment is developed in this work. The enhancement of oxygen plasma resistance can provide the porous OSG for practical application in the multilevel interconnection. (C) 2002 The Electrochemical Society.
Design and fabrication of fiberlenses for optical recording applications
(2002-03-01)
Tien, CH
;
Lai, YC
;
Milster, TD
;
Shieh, HPD
;
光電工程學系
The novel design and fabrication of a microlens on the front end of a single-mode fiber is described. The beam quality and spot size for optical recording applications are analyzed. A hyperbolic-shaped microlens on a single-mode fiber with focused spot of 1/e(2) = 0.82 mum (x-direction) and 0.89 mum (y-direction) at similar to 145 mum working distance was achieved by a simple fabrication procedure.
A release combined scheduling scheme for non-uniform dependence loops
(2002-03-01)
Pean, DL
;
Chua, HT
;
Chen, C
;
資訊工程學系
;
Department of Computer Science
In general, synchronization mechanisms can be used to preserve dependence constraints in any nested loop, and can be combined with a loop scheduling scheme to form a uniform framework to obtain the correct execution order and balance workload distribution. Most current scheduling mechanisms cannot handle non-uniform dependence loops. In this paper, we propose a new combined scheduling scheme called Release Combined Scheduling for Non-uniform Dependence Loops (RCS) to schedule non-uniform dependence doubly-nested loops in multiprocessor systems. It combines both static and dynamic scheduling mechanisms in order to optimize the system performance. In our approach, initialisation of a set of scheduling information is based on the concept of the minimum dependence distance. During runtime, scheduling information is used to adjust the number of parallelizable iterations. Our method is able to discover more parallelism from a given non-uniform dependence doubly-nested loop than is possible with previous approaches. The experimental results show that the RCS method reliably exploits parallelism and outperforms most of the existing non-uniform dependence loop scheduling schemes by 20.29%, on average.
Group testing in bipartite graphs
(2002-03-01)
Juan, ST
;
Chang, GJ
;
應用數學系
;
Department of Applied Mathematics
This paper investigates the group testing problem in graphs as follows. Given a graph G = (V, E), determine the minimum number t(G) such that t(G) tests are sufficient to identify an unknown edge e with each test specifies a subset X subset of or equal to V and answers whether the unknown edge e is in G[X] or not. Damaschke proved that [log(2) e(G)] less than or equal to t(G) less than or equal to [log(2) e(G)] + 1 for any graph G, where e(G) is the number of edges of G. While there are infinitely many complete graphs that attain the upper bound, it was conjectured by Chang and Hwang that the lower bound is attained by all bipartite graphs. This paper verifies the conjecture for bipartite graphs G with e(G) less than or equal to 2(4) or 2(k-1) < e(G) less than or equal to 2(k-1) + 2(k-3) + 2(k-6) + 19(.)2(k-7/2) -1 for k greater than or equal to 5.
An electro-thermally driven microactuator with two dimensional motion
(2002-03-01)
Wu, CT
;
Hsu, W
;
機械工程學系
;
Department of Mechanical Engineering
In previous literatures, most of the microactuators were designed to deflect in one dimension only. Here, an electro-thermally driven microactuator with out-of-plane and in-plane two dimensional motion is designed, fabricated and tested. This microactuator comprised of a series of bimorph beams, a moving plate, a lateral driven unit, and contact pads. The out-of-plane motion is produced due to the bimorph effect and residual stress between the layers of Au and polysilicon when they are heated. The in-plane motion is obtained by heating the lateral driven unit which consists of two adjacent beams with different cross sections but the same length, then the asymmetrical thermal expansions in two adjacent beams lead to lateral deflection. The microactuator proposed here is fabricated by surface micromaching technique. A twostep releasing method is used here to free the microactuator successfully. The testing results show that the lateral driven unit can produce 10 mum lateral displacements at input voltages of 5 V, and bimorph structures at the same voltage can produce about 12 mum downward displacement. It is also found that this two dimensional motion can be controlled almost independently.
Diamond deposition on Si (111) and carbon face 6H-SiC (0001) substrates by positively biased pretreatment
(2002-03-01)
Chang, TF
;
Chang, L
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The growth of textured diamond films on Si (111) and carbon face 6H-SiC (0001) has been achieved by positive bias-enhanced-nucleation in microwave plasma chemical vapor deposition. A bias voltage of + 100 to +300 V, 3% CH4 concentration in bias step, and 0.33% CH4 concentration in growth step were used to synthesize diamond films on Si and carbon face 6H-SiC. Highly oriented diamond films were observed by scanning electron microscopy and X-ray diffraction patterns. Cross-sectional transmission electron microscopy showed that the interface between diamond and Si substrate was smooth, while it was rough between diamond and SiC. It also showed that diamond films were directly grown on both substrates. (C) 2002 Elsevier Science B.V. All lights reserved.