Browsing by Issue Date, starting with "2004-10-05"

Now showing 1 - 20 of 69376

DC to 6-Ghz high-gain low-noise GaInP/GaAs HBT direct-coupled amplifiers with and without emitter-capacitive peaking
(2004-10-05)
Meng, CC
;
Wu, TH
;
Lu, SS
;
電信工程研究所
;
Institute of Communications Engineering
High-gain shunt-series shunt-shunt wideband amplifiers with and without emitter-peaking capacitors are demonstrated by using GaInP/GaAs HBT technology. Experimental results show that the power gain is 28 dB front DC to 6 GHz for a wideband amplifier without emitter-peaking capacitors. On the other hand, a wideband amplifier with emitter-peaking capacitors can increase the gain bandwidth up to 8 GHz at the cost of lower input/output return loss. Both circuits have similar power and noise performance. The noise figures of both designs are less than 2.8 dB for frequencies below 6 GHz,. Op(1dB) and OIP3 are 7 and 20 dBin at 2 GHz, respectively. Total current consumption is 67 mA at 5-V supply voltage for both wideband amplifiers. (C) 2004 Wiley Periodicals, Inc.
A GaInP/GaAs HBT micromixer for 2.4/5.2/5.7-Ghz multiband WLAN applications
(2004-10-05)
Wang, CY
;
Lu, SS
;
Meng, CC
;
Lin, YS
;
電信工程研究所
A GaInP/GaAs HBT micromixer for 2.4/5.2/5.7-GHz multiband WLAN applications is demonstrated. Our experimental results show that the input return loss |S-11| is below -25 dB from DC to 10 GHz with power-conversion gains of 11.7, 11.9, and 11.5 dB at frequencies of 2.4, 5.2, and 5.7 GHz, respectively. The wideband matching characteristic makes the micromixer very suitable for multiband applications. Input P-IdB is -4 dBm and IIP3 is 2.36 dBm. Port-to-port isolation is also quite satisfactory. In addition, the single-to-differential input stage in the Gilbert micromixer eliminates the need for common-mode rejection. (C) 2004 Wiley Periodicals, Inc.
Guided-wave microlens array applications to compact 1x8 planar waveguide splitters
(2004-10-05)
Chang, CW
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
A compact 1 x 8 waveguide splitter using a guided-wave microlens array is presented and analyzed to show low insertion loss and output imbalance of 0.28 and 0.15 dB, respectively. The analysis results show that the proposed equal-power splitter with insensitive wavelength responses and acceptable fabrication tolerances is applicable for compact and wide-bandwidth integrated optical devices. (C) 2004 Wiley Periodicals, Inc.
Effect of surface-hydroxylated CdS nanoparticles on the morphological transformation of polystyrene-block-poly(ethylene oxide) thin films
(2004-10-06)
Yeh, SW
;
Chang, YT
;
Chou, CH
;
Wei, KH
;
材料科學與工程學系
Polystyrene-block-poly(ethylene oxide) (SEO) block copolymer thin films, in which CdS clusters have been sequestered into the PEO domains of the SEO block copolymers, are found to induce the morphological transformation of PEO from cylinders to spheres, as shown by using atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). This transformation is caused by the presence of hydrogen-bonding interactions between surface-hydroxylated CdS and PEO, as confirmed by nuclear magnetic resonance (NMR) studies.
i-Genome: A database to summarize oligonucleotide data in genomes
(2004-10-09)
Lin, FM
;
Huang, HD
;
Chang, YC
;
Horng, JT
;
生物資訊及系統生物研究所
Background: Information on the occurrence of sequence features in genomes is crucial to comparative genomics, evolutionary analysis, the analyses of regulatory sequences and the quantitative evaluation of sequences. Computing the frequencies and the occurrences of a pattern in complete genomes is time-consuming. Results: The proposed database provides information about sequence features generated by exhaustively computing the sequences of the complete genome. The repetitive elements in the eukaryotic genomes, such as LINEs, SINEs, Alu and LTR, are obtained from Repbase. The database supports various complete genomes including human, yeast, worm, and 128 microbial genomes. Conclusions: This investigation presents and implements an efficiently computational approach to accumulate the occurrences of the oligonucleotides or patterns in complete genomes. A database is established to maintain the information of the sequence features, including the distributions of oligonucleotide, the gene distribution, the distribution of repetitive elements in genomes and the occurrences of the oligonucleotides. The database can provide more effective and efficient way to access the repetitive features in genomes.
Performance of a write-once multilayer optical disk that uses transparent recording material with an optical switching layer
(2004-10-10)
Wu, FH
;
Shieh, HPD
;
Huang, DR
;
Milster, TD
;
光電工程學系
A volumetric optical disk that has multiple transparent films with optical switching layers is used as a recording medium to increase the number of recording layers. In the disk the optical switching layer is adapted to reduce decay of laser energy and increase reading and recording sensitivity. Well-defined marks of similar to100-nm depth can be placed precisely on the transparent films by a focused laser beam. Writing and reading of a four-layer recordable disk, fabricated by molding and spin bonding, have been demonstrated experimentally. The volumetric disk can achieve a high recording capacity with conventional optical pickups. (C) 2004 Optical Society of America.
Face selectivity in the reactions of 2,4-disubstituted adamantanes and their modification by inclusion in beta-cyclodextrin solutions
(2004-10-11)
Chu, JH
;
Li, WS
;
Chao, I
;
Chung, WS
;
應用化學系
Sodium borohydride reduction reactions on 4-X-adamantan-2-ones (where X=ethyleneketal 11, ethylenethioketal 12, and methylene 15) were studied, which gave Z-alcohols 16 and 17 (from en-face attack) as the predominant products for ketones 11 and 12, but gave 1: 1 mixture of Z- and E-18 alcohols for ketone 15. The en/zu face selectivity of 15 in sodium borohydride reduction was enhanced to 32/68 in beta-CD solution. Both 1,3-dipolar addition and dichlorocarbene addition reactions on 4-ethyleneketal-2-methyleneadamantane 13 underwent again predominant en-face attack to give products in an E/Z ratio of > 99:1 and 92:8, respectively. The exceptional high zu-face selectivity on the dichlorocarbene addition reaction of 15 may be explained by a temporal complexation between the carbene and the C-4-oxo group. In the epoxidation reaction of 13 and 15 the zu-face attack products were favored despite their steric congestions suggesting that hydrogen bonding interaction between the peroxide reagent and the C-4-oxo or 4-ethyleneketal is involved. (C) 2004 Elsevier Ltd. All rights reserved.
Microphotoluminescence spectra of hillocks in Al0.11Ga0.89N films
(2004-10-11)
Ke, WC
;
Ku, CS
;
Huang, HY
;
Chen, WC
;
Lee, L
The spatial variation of the optical properties of hillocks in Al0.11Ga0.89N films has been studied by using microphotoluminescence (mu-PL) microscopy. The mu-PL spectrum revealed a strong emission (I-H) at 351 nm from the hillock, besides the near-band-edge emission (I-nbe) at 341 nm. Moreover, the I-H intensity increases significantly and its full width at half maximum decreases from similar to76 to similar to53 meV by probing across the hillock center. These indicated that the hillock structure is a strong emission center. The temperature-dependent mu-PL, measurements showed that the I-H also has the S-shape behavior with a transition temperature of similar to120 K which is lower than that of I-nbe. The redshift of I-H is also smaller than I-nbe. Both indicated that the Al composition in hillocks is lower than the surrounding area. (C) 2004 American Institute of Physics.
Stable styrylamine-doped blue organic electroluminescent device based on 2-methyl-9,10-di(2-naphthyl)anthracene
(2004-10-11)
Lee, MT
;
Chen, HH
;
Liao, CH
;
Tsai, CH
;
Chen, CH
We have developed a highly efficient and stable blue organic electroluminescent (EL) device based on. a blue fluorescent styrylamine dopant, p-bis(p-N,N-diphenyl-aminostyryl)benzene, in a morphologically stable high band-gap host material, 2-methyl-9, 10-di(2-naphthyl)anthracene, which achieved an EL efficiency of 9.7 cd/A and 5.5 lm/W at 20 mA/cm(2) and 5.7 V,with Commission Internationale d'Eclairage coordinates of (x=0.16, y=0.32). The blue-doped device achieved a half-decay lifetime (t(1/2)) of 46000 h at an initial brightness of 100 cd/m(2). (C) 2004 American Institute of Physics.
Defect-enhanced photoconductive response of silicon-implanted borosilicate glass (vol 85, pg 935, 2004)
(2004-10-11)
Lin, GR
;
Lin, CJ
;
Lin, CK
;
光電工程學系
;
Department of Photonics
Critical length of nanowires for hydrophobic behavior
(2004-10-11)
Cheng, YH
;
Chou, CK
;
Chih, C
;
Cheng, SY
;
材料科學與工程學系
This Letter investigates the wetting behavior on surface with well-controlled nanoscale structure. Water and water-alcohol droplets were brought to contact the surface electroplated by Ag nanowires. It is found that hydrophobic behavior becomes more pronounced as the length of the nanowires increases. A critical length of approximately 100 nm is observed, beyond which the contact angle approaches a steady value of 130degrees. In addition, the contact angle of water levels off around 160degrees when the length of the fluorine-coated Ag nanowires exceeds the critical value of 100 nm. The mechanism of the hydrophobic behavior on surface with nanoscale structure is proposed. (C) 2004 Elsevier B.V. All rights reserved.
Adjusting mechanism for flying pickup head in data storage device
(2004-10-14)
Tzong-Shi, Liu
;
Po-Ching, Liu
;
Hsing-Cheng, Yu
The present invention provides a tuning mechanism for flying pickup heads in data storage devices. The pickup device includes a coil, a pivot, a suspension, and a piezoelectric bender. The piezoelectric bender made by a bi-layer or a multi-layer piezoelectric material is formed on one end of the suspension, and proper voltages applied to the piezoelectric bender via wires enable the piezoelectric bender to undergo both neutral axis displacement and bending deflection. A pickup head is attached to the free end of the piezoelectric bender opposite to the coil, and via the piezoelectric bender, focusing and tracking motion of the pickup head can be tuned at the same time. Furthermore, since the characteristic of the piezoelectric bender is similar to bimetallic elements, the bender can undergo large bending deflection to compensate large deformation of rotating optical disks, so that the flying height of the pickup head can be tuned to maintain a constant focusing distance in reading/writing data.
High-voltage amplifier uses simplified circuit
(2004-10-14)
Tsai, JI
;
Shieh, JM
;
Liao, TS
;
Teng, CC
;
交大名義發表
Process for preparing positive-negative blended optical retardation film, positive-negative blended optical retardation film, and liquid crystal display element and liquid crystal display device using the same
(2004-10-14)
Long-Hai, Wu
;
Chain-Shu, Hsu
;
Ching-Hua, Ting
The invention provides a process for preparing a positive-negative-blended optical retardation film comprising coating a solution consisting of discotic and rod-like liquid crystal onto an alignment layer after unidirectionally rubbing treatment on a substrate, subsequently heating the coating to obtain a film consisting of discotic and rod-like liquid crystal with uniform arrangement, and then curing it through exposing under a UV-irradiation to obtain a positive-negative-blended optical retardation film with excellent viewing angle; and a positive-negative-blended optical retardation film. Further, the invention also provides a liquid crystal element and a liquid crystal device having said positive-negative-blended optical retardation film.
Influence of the aspect ratio of bioactive nanofillers on rheological behavior of PMMA-based orthopedic materials
(2004-10-15)
Liu, TY
;
Chen, SY
;
Liu, DM
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In this investigation, calcium-deficient hydroxyapatite (CDHA) nanocrystals with needle-like geometry were synthesized and incorporated with Poly(methyl methacrylate), PMMA, to form CDHA-PMMA nanocomposites. Rheological behaviors of the PMMA-CDHA melting suspensions were systematically investigated in terms of solid loading and aspect ratio of the CDHA nanoparticles. The maximum solid loadings of nano-CDHA particles with aspect ratios of 7.2, 10.4, and 17 were determined to be 28, 31, and 57%, respectively. An increase in solid concentrations causes pronounced shear-thinning behavior. This result suggests that a strong interaction, including Van der Waals attraction and mechanical interlocking, between the nano-CDHA particles makes the nanocomposite mixture more non-Newtonian. Furthermore, it was found that packing efficiency and yield strength in the suspension were strongly influenced by the aspect ratio, especially above the critical value of 8.8. The obtained critical aspect ratio and solid content provide not only appropriate design in the PMMA-CDHA polymeric suspension for fabrication process but also optimal conditions for the fabrication of orthopedic devices via injection molding or extrusion. (C) 2004 Wiley Periodicals, Inc.
Effects of compressive epitaxial strain on the magnetotransport properties of single-phase electron-doped La0.7Ce0.3MnO3 films
(2004-10-15)
Chang, WJ
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
;
Uen, TM
Single-phase electron-doped manganite thin films with nominal composition of La0.7Ce0.3MnO3 (LCeMO) have been prepared on SrTiO3 (100) substrates by pulsed laser deposition. The conditions for obtaining purely single-phase LCeMO films lie within a very narrow window of substrate temperature (T(s)similar to720 degreesC) and laser energy density (E(D)similar to2 J/cm(2)) during deposition. In situ postdeposition annealing, mainly to relax the possible epitaxial in-plane tensile strain between the film and the substrate, leads to an increasing c-axis lattice constant accompanied by the formation of secondary CeO2 phase and higher metal-insulator transition temperature. This is indicative of a strong coupling between the electron and lattice degree of freedom. (C) 2004 American Institute of Physics.
RoVegas: a router-based congestion avoidance mechanism for TCP Vegas
(2004-10-15)
Chan, YC
;
Chan, CT
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
Transmission control protocol (TCP) Vegas detects network congestion in the early stage and successfully prevents periodic packet loss that usually occurs in TCP Reno. It has been demonstrated that TCP Vegas outperforms TCP Reno in many aspects. However, TCP Vegas suffers several problems that inhere in its congestion avoidance mechanism, these include issues of rerouting, persistent congestion, fairness, and network asymmetry. In this paper, we propose a router-based congestion avoidance mechanism (RoVegas) for TCP Vegas. By performing the proposed scheme in routers along the round-trip path, RoVegas can solve the problems of rerouting and persistent congestion, enhance the fairness among the competitive connections, and improve the throughput when congestion occurs on the backward path. Through the results of both analysis and simulation, we demonstrate the elfectiveness of RoVegas. (C) 2004 Elsevier B.V. All rights reserved.
Microwave properties of a Y0.7Ca0.3Ba2Cu3O7-delta inicrostrip ring resonator with various hole concentrations
(2004-10-15)
Lai, LS
;
Juang, JY
;
Wu, KH
;
Uen, TM
;
Lin, JY
Superconducting ring resonator with a Y0.7Ca0.3Ba2Cu3O7-delta ground plane was fabricated by using Y0.7Ca0.3Ba2Cu3O7-delta thin film deposited on both sides of a LaAlO3 (LAO) substrate. The resonator exhibits a high quality factor Q > 10(4) at T < 30 K, and from empirical relation,T-c/T-c,T-max = 1 - 82.6(p - 0.16)(2), we obtained the hole concentration p. By controlling the oxygen contents of the ring resonator, the hole concentration p was controlled from 0.218 to 0.088, determined by the empirical relation, in the same film. The temperature dependence of the resonance frequency, f(T), was then systematically studied. By using Chang's inductive formula and taking a functional form (lambda(5K)/lambda (T))(2) = 1 - (T/T-c)(2) at T < 0.6T(c), the London penetration depths lambda(5K) for various oxygen contents at 5K were obtained, respectively. Finally, it allows us to test the Uemura relation 1 /lambda(2)(5K) proportional to T-c from the over- to the underdoped regime in the same sample. (C) 2004 Elsevier B.V. All rights reserved.
Investigation of GaN LED with Be-implanted Mg-doped GaN layer
(2004-10-15)
Huang, HW
;
Kao, CC
;
Chu, JT
;
Kuo, HC
;
Wang, SC
We report the electrical and optical characteristics of GaN light emitting diode (LED) with beryllium (Be) implanted Mg-doped GaN layer. The p-type layer of Be-implanted GaN LED showed a higher hole carrier concentration of 2.3 x 10(18)CM(-3) and low specific contact resistance value of 2.0 x 10(-4) Omegacm(2) than as-grown p-GaN LED samples without Be-implantation. The Be-implanted GaN LEDs with InGaN/GaN MQW show slightly lower light output (about 10%) than the as-grown GaN LEDs, caused by the high RTA temperature annealing process. (C) 2004 Elsevier B.V. All rights reserved.
Accelerating network security services with fast packet classification
(2004-10-15)
Shieh, S
;
Lee, FY
;
Lin, YW
;
資訊工程學系
;
Department of Computer Science
To protect a network, secure network systems such as intrusion detection system (IDS) and firewall are often installed to control or monitor network traffic. These systems often incur substantial delay for analyzing network packets. The delay can be reduced with fast packet classification, which can effectively classify network traffic, and consequently accelerate the analysis of network packets. In the last few years, many researchers devoted to providing fast packet classification methods for multidimensional classifier. However, these methods either suffer from poor performance and huge storage requirement, or are lack of dimension scalability. In this paper, we propose a packet classification method based on tuple space search, and use the multidimensional binary search tree (Kd-tree) to improve search performance. The proposed scheme requires only O(d log W) search time and controlled storage requirement, where d is the number of dimensions, and W is the utmost bit length for specifying prefixes in a classification rule. It features fast packet classification, and supports dynamic update which is a basic requirement of many secure network services, such as IDS and firewall. (C) 2004 Elsevier B.V. All rights reserved.