Browsing by Issue Date, starting with "2009-06-18"

Now showing 1 - 20 of 50463

Optical frequency doubling for multichannel radio-over-fibre system based on integrated phase modulator and silicon coupled microring notch filter
(2009-06-18)
Xu, L.
;
Li, C.
;
Tsang, H. K.
;
Chow, C. W.
;
光電工程學系
An integrated optical millimetre-wave signal generator based on a coupled microring resonator, which doubles the frequency of the electrical signal driving a phase modulator, is proposed and experimentally demonstrated for future radio-over-fibre systems. The coupled microring notch filter was fabricated on a silicon-on-insulator wafer. A high extinction ratio optical millimetre-wave signal was obtained.
SELF-AWARE ADAPTIVE POWER CONTROL SYSTEM AND A METHOD FOR DETERMINING THE CIRCUIT STATE
(2009-06-18)
HSIEH, Wei-Chih
;
Hwang, Wei
The present invention provides a self-aware power control system and a method for determining the circuit state. The self-aware adaptive power control architecture comprises of a multi-mode power gating network, a current monitoring translator, a variable threshold comparator, a slack detector, and a bi-directional shift register. The multi-mode power gating network controls the amount of supply current and hence the circuit speed. The power gating network can be composed of either N-type MOSFETs for virtual ground insertion or P-type MOSFETs for virtual supply insertion. The number of MOSFETs in the multi-mode power gating network can be configured according to the supply range and step difference of the supply current. Then, by monitoring the current characteristics drained by target circuit, the circuit state can be determined. No delay matching circuit is required. Together with other peripherals, the supply current can be down controlled to a minimum acceptable level. The circuit will use up all available slack. The smaller current implies lower power consumption as well. Furthermore, the present invention is capable of self adaptation to frequency change. To summarize, the present invention can make the circuit consume least power under various frequency achieving best power efficiency.
10 GHz dual-conversion low-IF downconverter with microwave and analogue quadrature
(2009-06-18)
Syu, J. -S.
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Meng, C.
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Teng, Y. -H.
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電信工程研究所
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Institute of Communications Engineering
A 10 GHz dual-conversion low-IF downconverter using 0.18-mm CMOS technology is demonstrated. The high-frequency quadrature RF and LO(1) signals are generated by broadside-coupled quadrature couplers while a two-section polyphase filter is utilised for the low-frequency LO(2) quadrature signal generation. As a result, the demonstrated downconverter achieves a conversion gain of 7 dB, IP(1dB) of -16 dBm, IIP(3) of 25 dBm and noise figure of 26 dB at a 1.8 V supply. The image-rejection ratio of the first/second image signal is 33/42 dB for IF frequency ranging from 10 to 60 MHz, respectively.
Quantum Chemical Modeling of Photoabsorption Properties of Two- and Three-Nitrogen Vacancy Point Defects in Diamond
(2009-06-18)
Zyubin, A. S.
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Mebel, A. M.
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Hayashi, M.
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Chang, H. C.
;
Lin, S. H.
Quantum chemical calculations of the geometric and electronic structures and vertical transition energies for several low-lying excited states of the neutral and negatively charged vacancy-related point defects in diamond containing two and three nitrogen atoms (N(2)V(0), N(2)V(-), and N(3)V(0)) have been performed employing various theoretical methods (time-dependent density functional theory, equation-of-motion coupled cluster, and multireference perturbation theory) and different basis sets and using C(21)H(28), C(35)H(36), and C(51)H(52) finite model clusters. In the;round states, the vacancy-related atoms are found to be shifted away from the vacancy center by similar to 0.1 angstrom, whereas the positions of atoms from the second layer around them vacancy remain nearly unchanged, indicating a local character of geometry relaxation due to defects. The lowest excited states are formed with participation of the stretched (N(2)V) or broken (N(3)V) C-C bond and nonbonding combinations of nitrogen lone pairs as donors, with the C-C antibonding molecular orbital (MO) in N(2)V(0), broken C-C bond in N(3)V(0), and diffuse vacancy-related MOs serving as acceptors. Normally, the first excited states have a valence character, but the diffuse states are rather close in energy, especially for N(3)V(0) (2(2)A(1) and 1(2)E excited states). The first optically active excitation in the N(2)V(0) defect with the calculated energy of similar to 2.6 eV (in close agreement with the experiment) is formed by the electronic transition from the stretched C-C bond to the antibonding C-C MO, with an additional contribution from the combination of nitrogen lone pairs. For the negatively charged N(2)V(-) system, the lowest excitation to the 1(2)A(1) state is predicted to occur from the singly occupied antibonding b(1) MO to the empty diffuse a(1) orbital, but the CASPT2 calculated excitation energy, similar to 0.9 eV, underestimates the experimental zero phonon line observed at 1.26 eV. The lowest excited states of N(3)V(0), 2(2)A(1), and 1(2)E correspond to transitions from the singly occupied MO (SOMO) to the diffuse lowest vacant orbital and from the nonbonding combination of nitrogen lone pairs to SOMO, respectively, and have similar energies of about 3.1-3.3 eV, in agreement with the experimental photoabsorption band maximum at similar to 3 eV.
Supramolecular self-assembly through inclusion complex formation between poly(ethylene oxide-b-N-isopropylacrylamide) block copolymer and alpha-cyclodextrin
(2009-06-19)
Tu, Cheng-Wei
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
應用化學系
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Department of Applied Chemistry
A well-defined poly(ethylene oxide-block-N-isopropylacrylamide) (PEO-b-PNIPAM) diblock copolymer was synthesized by atom transfer radical polymerization and formed the inclusion complexes (ICs) after selective threading of the PEO segment of the block copolymer through the cavities of alpha-cyclodextrin (alpha-CD) units. The formation of the alpha-CD/PEO ICs between alpha-CD and PEO segment of the PEO-b-PNIPAM transformed the system from its original random coil conformation into a rod/coil-like structure. The stacking of the alpha-CD/PEO ICs and phase separation within the alpha-CD/PEO-b-PNIPAM IC resulted in the self-assembly of long-range-ordered lamellar structure exhibiting alternating layers of (i) alpha-CD/PEO ICs with hexagonally packed plates and (ii) amorphous phase of unincluded PEO/PNIPAM with brush conformation. (C) 2009 Elsevier Ltd. All rights reserved.
Vibration analysis of rectangular plates with side cracks via the Ritz method
(2009-06-19)
Huang, C. S.
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Leissa, A. W.
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土木工程學系
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Department of Civil Engineering
This analysis deals with Free vibrations of a rectangular plate with a side crack by using the famous Ritz method with special displacement functions. To appropriately describe the stress singularities at the crack tip and show the discontinuities of displacement and slope crossing the crack, previously used corner functions, as well as a new set of functions, are added to the well known admissible functions consisting of regular polynomials. Comprehensive convergence studies oil the vibrations Of simply Supported rectangular plates with horizontal cracks at the symmetry axis are carried out and show that both the corner functions and the proposed new set of functions indeed accelerate the convergence of numerical solutions. Furthermore. the new Set Of functions is found to be particularly capable in improving convergence of Solutions, especially when there is a large crack. Convergence studies also demonstrate that the present approach gives more accurate results than previously published approaches using the Ritz method combined with various domain composition techniques. Finally, the present approach is applied to investigate the effects of location, length and orientation of side cracks oil the free vibration frequencies and mode shapes of simply supported and completely free square plates with side cracks. including cracks which are not along a symmetry axis, are skewed. Most of the results shown are novel. (C) 2009 Elsevier Ltd. All rights reserved.
Liquid crystal panel for high efficiency barrier type autostereoscopic three-dimensional displays
(2009-06-20)
Chen, Cheng-Huan
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Huang, Yi-Pai
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Chuang, Shang-Chih
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Wu, Chi-Lin
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Shieh, Han-Ping D.
An autostereoscopic display with parallax barrier attached onto a liquid crystal panel suffers from the trade-off between brightness and crosstalk. One approach for making improvement by modifying the layout of light blocking components, such as thin film transistor, storage capacitor, and protrusion, in the liquid crystal pixel has been proposed. Ray tracing simulation shows that the aperture of the slanted barrier can be significantly increased, hence increasing efficiency, while keeping the same crosstalk level if those light blocking components can be shifted to the corner of the pixel. A six-view 2.83 in. (7.19 cm) prototype has shown improvement on both brightness and crosstalk compared to its counterpart using a traditional liquid crystal panel, which demonstrates an effective approach for a high-efficiency barrier-type autostereoscopic 3D display with a liquid crystal panel. (C) 2009 Optical Society of America
便當志工散播關懷散播愛
(2009-06-21)
梁素茵
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Department of Communication and Technology
;
傳播與科技學系
便當志工
大專排球大改制各校觀望
(2009-06-21)
陳碩峰
;
Department of Communication and Technology
;
傳播與科技學系
123
發光二極體裝置以及其製造方法
(2009-06-21)
鄭裕國
;
陳勇智
;
謝漢萍
本發明提供一種發光二極體裝置及其製造方法。根據本發明之發光二極體裝置能用以穩固地安裝至少一發光二極體,並且維持該至少一發光二極體之電性導通。此外,該發光二極體裝置包含一基板、一容置結構、一固定結構以及複數個電極。該容置結構形成於該基板上,用以容納該固定結構以及該至少一發光二極體。該固定結構,設置於該容置結構中,用以固定該至少一發光二極體。該複數個電極係用以將該至少一發光二極體電連接至一電源及/或一信號源。更重要地,該容置結構係一插座狀結構或一凹槽狀結構。
The Pancakes 稚氣好聲音
(2009-06-21)
林麗珊
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Department of Communication and Technology
;
傳播與科技學系
.
當web2.0遇上金盾工程
(2009-06-21)
邵奕儒
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Department of Communication and Technology
;
傳播與科技學系
金盾
J家飯在台灣
(2009-06-21)
楊雅筑
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Department of Communication and Technology
;
傳播與科技學系
QQ
交校園飲酒問題各執其見
(2009-06-21)
余建良
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Department of Communication and Technology
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傳播與科技學系
@@!!!
因為音樂而存在　日日春
(2009-06-21)
楊純芳
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Department of Communication and Technology
;
傳播與科技學系
日日春樂團從2006年9月至今，成立了兩年多的時間，這五位清華大學的女孩，因為音樂而連接在一起。鳳凰花開的日子到來，女孩們都要畢業了，面對主唱一云的離開，她們一同許下半年的約定，半年後，等一云回國，他們將一起完成日日春的第一張專輯，只要音樂還在，日日春就在。
原住民小孩學母語困境多
(2009-06-21)
葉曉昀
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Department of Communication and Technology
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傳播與科技學系
no
Tailoring switching properties of dipolar species in ferroelectric liquid crystal with ZnO nanoparticles
(2009-06-21)
Li, Liu-Shiaun
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Huang, Jung Y.
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光電工程學系
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Department of Photonics
The capacitance-voltage (C-V) characteristics of surface-stabilized ferroelectric liquid crystal (SSFLC) cells doped with zinc oxide nanocrystals (nc-ZnO) have been studied and fitted to the Preisach model to reveal the behaviours of dipolar species. To explain the experimental results, we propose a physical picture depicting an interaction of nc-ZnO dipole with surrounding SSFLC dipolar species. Our study shows that doping nc-ZnO into FLC not only increases the contrast ratio of the cells by 10 times but also enhances the dynamic polarization of the beneficial dipolar species while minimizing the polarization response of the species with counter effects.
Implementation of Fuchs' model of ion diffusion charging of nanoparticles considering the electron contribution in dc-corona chargers in high charge densities
(2009-06-21)
Aliat, A.
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Hung, C. T.
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Tsai, C. J.
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Wu, J. S.
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機械工程學系
A 1D corona discharge model coupled to a 2D-axisymmetric particle charging model are proposed in this paper to simulate nanoparticle charging process within a wire-tube air corona discharge subjected to an applied positive or negative dc voltage. This 1D discharge model provides the distribution of the electric field, the air ion and free electron concentrations for the 2D charging model which in turn solves the spatial distributions of the various charged nanoparticles within the tube. This 2D charging model takes into account the effect of electrons, on the basis of Fuchs' law usually employed in the literature for modelling of ion diffusion nanoparticle charging. The current approach is valid when the concentration of nanoparticles is much lower than the concentration of ionic species in the gas. Numerical results show that the positive air ions can be assumed to be solely responsible for the charging process in a positive air corona charger, while both the negative air ions and electrons play an important role in the negative charging. At high negative charge intensities, the effect of the electrons becomes appreciable due to their high conduction velocity. In general, the numerical results obtained are in good agreement with the experimental data reported in the literature.
新兩性形象《女男變錯身》
(2009-06-21)
徐苾芬
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Department of Communication and Technology
;
傳播與科技學系
呵呵呵呵最後一篇了
住哪好清齋交舍比一比
(2009-06-21)
王成宇
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Department of Communication and Technology
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傳播與科技學系
清交的宿舍照片比一比