Browsing by Issue Date, starting with "2008-06-28"

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Equivalence of permutation polytopes corresponding to strictly supermodular functions
(2008-06-28)
Hwang, Frank K.
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Lee, J. S.
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Rothblum, Uriel G.
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應用數學系
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Department of Applied Mathematics
This paper demonstrates a strong equivalence of all permutation polytopes corresponding to strictly supermodular functions. (C) 2007 Elsevier B.V. All rights reserved.
Influence of plasma collective effects on cosmological evolution
(2008-06-28)
Lai, Kwang-Chang
;
Chen, Pisin
;
物理研究所
;
Institute of Physics
It is well-known that the universe was in a plasma state both before decoupling and after reionization. However, the conventional wisdom has been that the plasma effects are largely Debye-shielded and can thus be safely ignored when considering large scale evolutions. Recently we showed that large scale structure formation in the universe may actually be suppressed by the plasma collective effect. Indeed, observational data indicate that the conventional theoretical formula tends to overestimate the matter power spectrum at scales k > 1hMpc(-1). In this paper, we further develop our theory through a more thorough and general derivation of the Maxwell-Einstein-Boltzmann equation. In addition to baryon density perturbation post reionization, we apply this general formulation to investigate the possible plasma effect on CMB anisotropy. As expected, while the plasma effect does render an observable effect to the former, its impact on the latter is totally negligible.
Synthesis of structurally diverse benzimidazolyl benzimidazolones by application of soluble polymer support
(2008-06-30)
Chen, Hsia-Yuan
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Kulkarni, Manohar V.
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Chen, Chih-Hau
;
Sun, Chung-Ming
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應用化學系
Chemical stability and reactivity of a bifunctional polymer conjugate containing an ortho-amino arylamide linkage have been successfully exploited to achieve a parallel synthesis of methoxycarbonylated head-tail bis-benzimidazoles. Regioselective alkylation of the two nitrogens in the benzimidazolone moiety has been carried out by ipso-fluoro displacement, and N-alkylation to generate two diversities. Cleavage of the polymer support has resulted in two libraries of di- and tri-substituted benzimidazolyl benzimidazolones in high purity and high yield. All reaction steps have been monitored by (1)H NMR on the support directly. (c) 2008 Elsevier Ltd. All rights reserved.
Electrooxidation of catecholamines at carbon nanotube-modified indium tin oxide electrodes
(2008-06-30)
Lin, Kuan-Wen
;
Lin, Chang-Hao
;
Hsieh, You-Zung
;
應用化學系
;
Department of Applied Chemistry
In this study, we prepared carbon nanotube (CNT)/Nafion-modified ITO electrodes and investigated their electrochemical behavior. The CNTs were dissolved in a solution of the ionic polymer Nafion and then CNT/Nafion composite films were deposited onto ITO electrodes through spin-coating of this homogeneous solution. We studied the effects of chemical pretreatment of the CNTs and the pH of the buffer on the electroanalytical behavior of the CNT/Nafion-modified ITO electrodes toward catecholamines. The modified electrodes enhanced the peak current and lowered the overpotentials. We observed high electrooxidative performance for the modified ITO electrodes: the oxidative currents of the catecholamines were up to 125-fold higher than those obtained using bare ITO electrodes. (C) 2008 Elsevier B.V. All rights reserved.
Correlations of instantaneous transition energy and intensity of absorption peaks during molecular vibration: toward potential hyper-surface
(2008-06-30)
Kobayashi, Takayoshi
;
Wang, Zhuan
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電子物理學系
;
Department of Electrophysics
Time-resolved spectrum after ultrashort pulse excitation revealed fine structure of instantaneous vibronic absorption spectra in a thiophene derivative. The probe photon energy-dependent amplitudes of molecular vibration coupled to the induced absorption were composed of several peaks. An absorbance-change peak-tracking method revealed four vibronic transitions buried in the time-integrated spectra over several vibrational periods of typical molecular vibration. Four vibronic transitions located at 2.024, 1.921, 1.818 and 1.731 eV were found to be correlated among themselves with respect to the photon energies and intensities of the peaks in the difference absorbance change spectra. From the size and sign of the correlation strengths the mechanism of the vibronic coupling was related to non-Condon mechanism and Herzberg-Teller vibronic coupling.
In-channel simplified decoupler with renewable electrochemical detection for microchip capillary electrophoresis
(2008-06-30)
Lin, Kuan-Wen
;
Huang, Yan-Kai
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Su, Hsiu-Li
;
Hsieh, You-Zung
;
應用化學系
Electrochemical (EC) detection is comparable to fluorescence detection in that it is simple to perform, economical, and highly sensitive. In this study, we used replica molding to fabricate a PDMS microchip for microchip capillary electrophoresis (CE). A decoupler electrode and a working electrode were implanted into the PDMS chip during the molding process to prevent leakage into the electrode channel. The working electrode could be renewed readily through its slight withdrawal (ca. 3 mm) from the PDMS; its detection ability was highly reproducible in the microchip CE-EC system. The relative standard deviation (R.S.D.) of the detecting current for the renewed working electrode was 1.2% (n = 5). The calibration curves were linear for both dopamine and catechol analytes over the concentration range 10-1000 mu M, with coefficients ofdetermination (R-2) of 0.999 and 0.976, respectively. The number of theoretical plates (N/m) for these analytes was greater than 133,000. (C) 2008 Elsevier B.V. All rights reserved.
The relation between the symmetry of vibrational modes and the potential curve displacement associated with electronic transition studied by using real-time vibrational spectroscopy
(2008-06-30)
Kobayashi, Takayoshi
;
Wang, Zhuan
;
Iwakura, Izumi
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電子物理學系
;
Department of Electrophysics
The relation between the vibronic coupling strength of the vibronic state combined with the optical transitions with short pulses and the symmetry of the coupled vibrational modes was studied by using multi-wavelength vibrational real-time spectroscopy. A pump-probe experiment of thiophene oligomers using 6.7 fs pulsed laser as an ultrashort pulse light source and a multi-channel lock-in amplifier as a broadband detector was performed to obtain simultaneously the real-time traces at 128 wavelengths. At all wavelengths, the absorbance changes were plotted against pump-probe delay time, which was between-200 and 2000 fs. The vibronic coupling in both the ground and excited states was classified into two types: the displaced (D) type with displaced potential surfaces and the non-displaced (ND) type with non-displaced potential surfaces between the two electronic studies. The D and ND types were found to be related to inversion anti-symmetric and symmetric molecular vibrations, respectively, with respect to the center of the pseudo-inversion symmetry of the molecule. The symmetry center is located at the middle point of the C=C bond connecting the two quinoid-type thiophene rings. It was shown that multi-wavelength measurement of the vibrational real-time spectroscopy provides information on the mechanism of vibronic coupling in the process of transition from the ground state to the excited state and that between the two excited states.
Fabrication of optical gratings by shrinkage of a rubber material
(2008-06-30)
Shih, Teng-Kai
;
Ho, Jeng-Rong
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Liao, Hung-Yu
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Chen, Chia-Fu
;
Liu, Chueh-Yang
Ordered wavy surface structures generated by deposition of a metal thin film on a pre-stretched PDMS plate were fabricated and its potential application for optical gratings was proposed. The orientation of the generated structures was always perpendicular to the pre-stretched direction and the pitch of the structure could be adjusted ranging from 4.5 mu m to 6.8 mu m by controlling the strength of the pre-stretched strain and the thickness of the surface metal film. Based on these periodic structures, various optical gratings were demonstrated. With a slight modification of the fabrication scheme, gratings with different orientations can be fabricated on both sides of the PDMS plate, the double-sided gratings, could be fabricated. It is believed the current method has the potential for the fabrication of a large-scale diffractive grating at lower costs. (C) 2007 Elsevier B.V. All rights reserved.
Quantitative limitation of active site and characteristics of chemical oxidized well-aligned carbon nanotubes
(2008-06-30)
Hung, Tsung-Chi
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Chen, Chia-Fu
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Chen, Mi
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Chen, Chien-Chung
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材料科學與工程學系
For many years, acid treatment processes have been used to modify substances for their applications on energy storage devices, such as electrochemical capacitors, fuel cells, etc. It is obvious that the increase of surface area and functional groups has beneficial influence on the amount of reactant adsorption. However, the quantitative limitation of active site has been poorly discussed until today. In this experiment, nitric acid (2 M and 14 M) was introduced at 90 degrees C over different periods of time to oxidate the well-aligned multi-wall carbon nanotubes (MWNTs), which were synthesized directly using carbon cloth (CC) as the substance. Quinoidal functional groups on active CNTs, such as -COOH and -OH, were found to be the result of chemical reaction. Pt catalyst, which was extracted from H2PtCl6 center dot 6H(2)O, was deposited onto the carbon nanotubes using electroless plating in chloroplatinic acid solution. The extent of Pt adsorption was measured and was substantially larger than the as-prepared CNTs. It was found that the state of quantitative limitation existed in both 2 M and 14 M systems. A model was also developed to illustrate the limitation in the active site due to the chemical oxidation. (C) 2007 Elsevier B.V. All rights reserved.
Excitonic and vibrational nonlinear processes in a polydiacetylene studied by a few-cycle pulse laser
(2008-06-30)
Kobayashi, T.
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Iwakura, I.
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Yabushita, A.
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電子物理學系
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Department of Electrophysics
High-density excitation of exciton induces the faster decay of absorbance change due to exciton-exciton interaction originated from the Auger recombination process. Experimental results clarified the dynamics of the exciton and the bimolecular quenching rate and the jump rate of exciton were determined to be 5.2 x 10(-9) cm(3) s(-1) and 5.2 x 10(-9) s(-1), respectively. The intensity modulation of electronic transition under high-density excitation with sub-5-fs pulse was analyzed to observe the Fourier power spectrum of the molecular vibration modes and revealed the existence of a combination tone (2726 cm(-1)) of the C-C (1241 cm(-1)) and the C=C (1485 cm(-1)) stretching modes. This indicates that the highly excited state induced by the Auger process results in the fusion of vibrational quantum states. Difference frequency generation of the vibrational modes also takes place in the same process due to the fission of the vibrational quanta stimulated by the interaction of the two vibrational modes. It was also found that the intensities of several prominent peaks corresponding to the modes of C=C and C-C stretching were proportional to the squared intensity of the probe pulse. Furthermore, the frequencies of the modes were shifted to low frequencies at high probe intensity. The process can be considered to be fifth-order cascaded Raman scattering via real excitation of vibronic excitons.
楓葉造反
(2008-07-01)
管管
AHP- and simulation-based budget determination procedure for public building construction projects
(2008-07-01)
Lai, Yu-Ting
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Wang, Wei-Chih
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Wang, Han-Hsiang
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土木工程學系
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Department of Civil Engineering
Public construction project budgets account for a high percentage of annual government budgets. Thus, objectively determining project budgets is of priority concern for effectively allocating these budgets by government officers. However, Taiwanese regulations for setting construction project budgets only qualitatively describe the governmental administration process. Without a systematic quantitative method, government officers typically determine project budgets based on their personal experience; thus, budgeting results can be unreliable. This study presents a novel procedure for determining construction project budgets. The proposed procedure integrates an analytical hierarchy process (AHP)-based multi-criteria evaluation model with a simulation-based cost model. The AHP reflects officer evaluations with respect to budget determination criteria. Cost items are variables. The cost model generates a cumulative cost distribution for establishing project budget boundaries. The merits of the proposed procedure are demonstrated through its application to a Taiwanese project. (C) 2007 Elsevier B.V. All rights reserved.
記憶裝置及其資料提供方法
(2008-07-01)
楊惠親
;
鍾崇斌
;
單智君
本發明係揭露一種記憶裝置及其資料提供方法,此記憶裝置接收一處理器所發送之初始指令位址之後,便可動態預測及產生下一個指令之位址,並以所產生之位址至記憶單元陣列提取指令,將此指令傳送予處理器。藉此,記憶裝置可自主性地向處理器傳送指令,不需等待處理器提供指令位址,因此本發明之記憶裝置及其資料提供方法可大幅地減少指令位址傳輸量。
Novel narrow-band-gap conjugated copolymers containing phenothiazine-arylcyanovinyl units for organic photovoltaic cell applications
(2008-07-01)
Li, Kuang-Chieh
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Hsu, Ying-Chan
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Lin, Jiann-T'Suen
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Yang, Chang-Chung
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Wei, Kung-Hwa
A series of novel narrow-band-gap copolymers (P1-P12) composed of alkyl-substituted fluorene (FO) units and six analogous mono- and bis(2-aryl-2-cyano-vinyl)- 10-hexylphenothiazine monomers (M1-M6) were synthesized by a palladium-catalyzed Suzuki coupling reaction with two different feed in ratios of FO to M1-M6 (molar ratio = 3:1 and 1:1). The absorption spectra of polymers P1-P12 exhibited broad peaks located in the UV and visible regions from 400 to 800 nm with optical band gaps at 1.55-2.10 eV, which fit near the wavelength of the maximum solar photon reflux. Electrochemical experiments displayed that the reversible p- and n-doping processes of copolymers were partially reversible, and the proper HOMO/LUMO levels enabled a high photovoltaic open-circuit voltage. As blended with [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) as an electron acceptor in bulk heterojunction photovoltaic devices, narrow-band-gap polymers P1-P12 as electron donors showed significant photovoltaic performance which varied with the intramolecular donor-acceptor interaction and their mixing ratios to PCBM. Under 100 mW/cm(2) of AM 1.5 white-light illumination, the device of copolymer P12 produced the highest preliminary result having an open-circuit voltage of 0.64 V, a short-circuit current of 2.70 mA/cm(2), a fill factor of 0.29, and an energy conversion efficiency of 0.51%. (c) 2008 Wiley Periodicals, Inc.
Establishing an invar leveling calibration system
(2008-07-01)
Chen, Chun-Sung
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Wu, Chien-Ting
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Chang, Ming-Wei
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Chang, Wei-Chen
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土木工程學系
Precise height systems are widely utilized in civil engineering projects Such as high-speed railroads, and highways and bridge construction. However, highly precise height data is obtained using precise leveling. An extremely precise invar leveling rod is necessary for obtaining precise results. In this study, an automatic calibration system for invar leveling has been established by the National Measurement Laboratory (NML). The content belongs to the long scales calibration system of D17 of the NML. This system utilizes a steady frequency laser interferometer, a CCD microscopic monitor, and a precise moving mechanism. With this system, an invar rod and a mark invar leveling rod are applied to estimate uncertainty with a 95% confidence level. Uncertainty results are 22 mu m and 21 mu m for the invar leveling rods and mark invar leveling rods, respectively.
A novel compact balanced-to-unbalanced low-temperature co-fired ceramic bandpass filter with three coupled lines configuration
(2008-07-01)
Chen, Kun-Tzu
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Chung, Shyh-Jong
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電信工程研究所
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Institute of Communications Engineering
This paper proposes a novel compact balanced-to-unbalanced bandpass filter. Firstly, a pre-design circuit is presented, which is composed of an inductive coupled-line bandpass filter and an out-of-phase capacitive coupled-line bandpass filter. A novel compact circuit with three coupled lines configuration, derived from the pre-design circuit, is then proposed for miniaturizing the balanced-to-unbalanced bandpass filter. A 2.4-GHz multilayer ceramic chip type balanced-to-unbalanced bandpass filter with a size of 2.0 mm x 1.2 mm x 0.7 mm is developed to validate the feasibility of the proposed structure. The filter is designed by using circuit simulation, as well as full-wave electromagnetic simulation softwares, and fabricated by the use of low-temperature co-fired ceramic technology. The measured results agree quite well with the simulated. According to the measurement results, the maximum insertion loss is 1.65 dB, the maximum in-band phase imbalance is within 3 degrees, and the maximum in-band magnitude imbalance is less than 0.32 dB.
Impact of process-induced strain on Coulomb scattering mobility in short-channel n-MOSFETs
(2008-07-01)
Chen, William P. N.
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Su, Pin
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Goto, K.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This letter provides an experimental assessment of Coulomb scattering mobility for advanced short-channel strained devices. By accurate mobility extraction under various temperatures, we examine the impact of process-induced uniaxial strain on Coulomb mobility in short-channel nMOSFETs. This letter indicates that the Coulomb mobility has significant stress dependency. Moreover, the stress sensitivity of the Coulomb mobility shows strong temperature, dependence. Because it is the interface scattering that counteracts the stress sensitivity of the bulk-impurity-limited mobility, further reducing the interface charges will be crucial to future mobility scaling.
Interactions of host IL-6 and IFN-gamma and cancer-derived TGF-beta 1 on MHC molecule expression during tumor spontaneous regression
(2008-07-01)
Hsiao, Ya-Wen
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Liao, Kuang-Wen
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Chung, Tien-Fu
;
Liu, Chen-Hsuan
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Hsu, Chia-Da
Many tumors down-regulate major histocompatibility complex (MHC) antigen expression to evade host immune surveillance. However, there are very few in vivo models to study MHC antigen expression during tumor spontaneous regression. In addition, the roles of transforming growth factor beta1 (TGF-beta 1), interferon gamma (IFN-gamma), and interleukin (IL)-6 in modulating MHC antigen expression are ill understood. We previously reported that tumor infiltrating lymphocyte (TIL)-derived IL-6 inhibits TGF-beta 1 and restores natural killing (NK) activity. Using an in vivo canine-transmissible venereal tumor (CTVT) tumor model, we presently assessed IL-6 and TGF-beta involvement associated with the MHC antigen expression that is commonly suppressed in cancers. IL-6, IFN-gamma, and TGF-beta 1, closely interacted with each other and modulated MHC antigen expression. In the presence of tumor-derived TGF-beta 1, host IFN-gamma from TIL was not active and, therefore, there was low expression of MHC antigen during tumor progression. TGF-beta 1-neutralizing antibody restored IFN-gamma-activated MHC antigen expression on tumor cells. The addition of exogenous IL-6 that has potent anti-TGF-beta 1 activity restored IFN-gamma activity and promoted MHC antigen expression. IFN-gamma and IL-6 in combination acted synergistically to enhance the expression of MHC antigen. Thus, the three cytokines, IL-6, TGF-beta 1, and IFN-gamma, closely interacted to modulate the MHC antigen expression. Furthermore, transcription factors, including STAT-1, STAT-3, IRF-1, NF-kappa B, and CREB, were significantly elevated after IL-6 and IFN-gamma treatment. We conclude that the host IL-6 derived from TIL works in combination with host IFN-gamma to enhance MHC molecule expression formerly inhibited by TGF-beta 1, driving the tumor toward regression. It is suggested that the treatment of cancer cells that constitutively secrete TGF-beta 1 should incorporate anti-TGF-beta activity. The findings in this in vivo tumor regression model have potential applications in cancer immunotherapy.
PERTURBATION RESULTS RELATED TO PALINDROMIC EIGENVALUE PROBLEMS
(2008-07-01)
Chu, E. K. -W.
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Lin, W. -W.
;
Wang, C. -S.
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應用數學系
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Department of Applied Mathematics
We investigate the perturbation of the palindromic eigenvalue problem for the matrix quadratic P(lambda) = lambda(2) A(1)* + lambda A(0) + A(1) with A(0), A(1) is an element of C(nxn) and A(0)* = A(0) (where * = T or H). The perturbation of eigenvalues in the context of general matrix polynomials, palindromic pencils, (semi-Schur) anti-triangular canonical forms and differentiation is discussed.
Duty phase control for single-phase boost-type SMR
(2008-07-01)
Chen, Hung-Chi
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a novel duty phase control (DPC) for single-phase boost-type switching-mode-rectifier (SMR) is developed and digitally implemented in DSP-based system. Compared to the conventional multiloop control structure with inner current loop and outer voltage loop, it is noted that there is only one voltage loop tuning the phase of predefined duty pattern (i.e. duty phase) in the proposed DPC. Due to no current loop, sampling inductor current and tracking current are unnecessary when SMRs are operated to shape the current waveform and regulate the output voltage. It implies that the single-loop DPC is simple and adaptable to the implementation with digital and analog integrated circuits. In this paper, first, the effect of the duty phase on the input current is analyzed and modeled. It shows that the sinusoidal current waveform can be naturally generated by the predefined duty pattern and the current amplitude is roughly proportional to the controllable duty phase. Then, a voltage controller is designed to regulate the dc output voltage by tuning this duty phase. Finally, some simulated and experimental results have been given to illustrate the performances of the proposed DPC.