Browsing by Issue Date, starting with "2012-01-18"

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Weak ferrimagnetism and multiple magnetization reversal in alpha-Cr(3)(PO(4))(2)
(2012-01-18)
Vasiliev, A. N.
;
Volkova, O. S.
;
Hammer, E.
;
Glaum, R.
;
Broto, J. -M.
The chromium(II) orthophosphate alpha-Cr(3)(PO(4))(2) is a weak ferrimagnet with the Curie temperature T(C) = 29 K confirmed by a lambda-type peak in specific heat. Dominant antiferromagnetic interactions in this system are characterized by the Weiss temperature Theta = 96 K, indicating an intermediate frustration ratio vertical bar Theta vertical bar/T(C) similar to 3. In its magnetically ordered states alpha-Cr(3)(PO(4))(2) exhibits a remarkable sequence of temperature-induced magnetization reversals sensitive to the protocol of measurements, i.e., either field-cooled or zero-field-cooled regimes. The reduction of the effective magnetic moment 4.5 mu(B)/Cr(2+), as compared to the spin-only moment 4.9 mu(B)/Cr(2+), cannot be ascribed to the occurrence of the low-spin state in any crystallographic site of the Jahn-Teller active 3d(4) Cr(2+) ions. X-ray absorption spectra at the K edge indicate divalent chromium and unravel the high-spin state of these ions at the L(2,3) edges. Weak ferrimagnetism and multiple magnetization reversal phenomena seen in this compound could be ascribed to incomplete cancellation and distortion of partial spontaneous magnetization functions of Cr(2+) in its six crystallographically inequivalent positions.
Weak ferrimagnetism and multiple magnetization reversal in alpha-Cr-3(PO4)(2)
(2012-01-18)
Vasiliev, A. N.
;
Volkova, O. S.
;
Hammer, E.
;
Glaum, R.
;
Broto, J. -M.
The chromium(II) orthophosphate alpha-Cr-3(PO4)(2) is a weak ferrimagnet with the Curie temperature T-C = 29 K confirmed by a lambda-type peak in specific heat. Dominant antiferromagnetic interactions in this system are characterized by the Weiss temperature Theta = 96 K, indicating an intermediate frustration ratio vertical bar Theta vertical bar/T-C similar to 3. In its magnetically ordered states alpha-Cr-3(PO4)(2) exhibits a remarkable sequence of temperature-induced magnetization reversals sensitive to the protocol of measurements, i.e., either field-cooled or zero-field-cooled regimes. The reduction of the effective magnetic moment 4.5 mu(B)/Cr2+, as compared to the spin-only moment 4.9 mu(B)/Cr2+, cannot be ascribed to the occurrence of the low-spin state in any crystallographic site of the Jahn-Teller active 3d(4) Cr2+ ions. X-ray absorption spectra at the K edge indicate divalent chromium and unravel the high-spin state of these ions at the L-2,L-3 edges. Weak ferrimagnetism and multiple magnetization reversal phenomena seen in this compound could be ascribed to incomplete cancellation and distortion of partial spontaneous magnetization functions of Cr2+ in its six crystallographically inequivalent positions.
Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of O-x (x=1 and 2) with Pristine and Defective Graphite (0001) Surfaces
(2012-01-19)
Xu, S. C.
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Chen, Hui-Lung
;
Lin, M. C.
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應用化學系分子科學碩博班
;
Institute of Molecular science
We present reaction pathways for adsorption reactions of the O atom and O-2 molecule in the pristine and monovacancy defective graphite (0001) based on quantum chemical potential energy surfaces (PESs) obtained by the dispersion-augmented density-functional tight-binding (DFTB-D) method. We use a dicircumcoronene C96H24 (L0D) graphene slab as the pristine graphite (0001) model and dicircumcoronene C95H24 (LIV) as the graphite (0001) monovacancy defect model. We found that the adsorption reactions of O and O-2 on the L0D surface can produce defects on the graphite surface. O can yield CO, while O-2 can yield both CO and CO2 molecules. The adsorption reactions of the O and O-2 on the LW surface can produce a 2-C defective graphite surface and CO, and CO and CO2, respectively. The O and O-2 more readily oxidize the defected surface, LIV, than the defect-free surface, L0D. On the basis of the computed reaction pathways, we predict reaction rate constants in the temperature range between 300 and 3000 K using Rice-Ramsperger-Kassel-Marcus (RRKM) theory. High-temperature quantum chemical molecular dynamics simulations at 3000 K based on on-the-fly DFTB-D energies and gradients support the results of our PES studies.
Optical Three-Dimensional Coordinate Sensor System and Method Thereof
(2012-01-19)
Chao Paul C.P.
;
Lin Tzu-Yang
;
Chen Wei-Dar
The present invention relates an optical three-dimensional coordinate sensor system and method thereof. A plurality of light-emitting modules produce a plurality of light signals, and then a plurality of reflected light signals reflected by an object are received by a plurality of photodetectors. After receiving the reflected light signals, the photodetectors generate a plurality of photocurrents. A plurality of active pixel circuits receive the photocurrents and transform the photocurrents to a plurality of reflective optical voltages. A plurality of differential amplifier circuits (DAC) compare the reflective optical voltages and the background voltages, and then output a plurality of DAC output voltages of the reflected light signals. Afterward, a processing module detects the DAC output voltages and uses an algorithm to calculate the top three of the DAC output voltages to determine the three-dimensional coordinate of the object.
交大e-News第110期
(2012-01-19)
Secretariat
;
國立交通大學秘書室
SCHMITT TRIGGER-BASED FINFET SRAM CELL
(2012-01-19)
Chuang Ching-Te
;
Hsieh Chien-Yu
;
Fan Ming-Long
;
Hu Pi-Ho
;
Su Pin
The present invention provides a Schmitt trigger-based FinFET static random access memory (SRAM) cell, which is an 8-FinFET structure. A FinFET has the functions of two independent gates. The new SRAM cell uses only 8 FinFET per cell, compared with the 10-FinFET structure in previous works. As a result, the cell structure of the present invention can save chip area and raise chip density. Furthermore, this new SRAM cell can effectively solve the conventional problem that the 6T SRAM cell is likely to have read errors at a low operating voltage.
畫素驅動電路及其驅動方法與應用
(2012-01-21)
蔡明憲
;
戴亞翔
本發明揭露一種畫素驅動電路及其驅動方法與應用，在不同的時序下，此畫素驅動電路中係分別藉由三個薄膜電晶體以做為儲存電容與液晶電容的開關，首先先對儲存電容充入足夠的電量，並且將液晶電容進行放電，最後，重置儲存電容與液晶電容之間的電荷以達到對液晶電容進行充電的目的。因此，藉由本發明之電路設計並同時配合上適當的時序控制，即使在應用色彩序列驅動法的顯示裝置中，係可避免停止逐列掃瞄來切換背光光源，故，畫素充電的時間與發光的時間皆不會縮短，同時亦可使顯示裝置在更高頻率下操作，以提供較佳的畫面品質。
磁性薄膜對液晶分子之水平及垂直配向方法
(2012-01-21)
趙如蘋
;
吳信穎
一種磁性薄膜對液晶分子之水平及垂直配向方法，係利用一直流離子濺鍍裝置(Direct-current Ion Sputter)所生成之透明磁性薄膜，可提供液晶分子幾近垂直排列之狀態。而在經由傳統摩刷處理後之透明磁性薄膜，則可更進一步提供有預傾角之水平或垂直排列之狀態。因此，藉由控制該透明磁性薄膜之成膜條件可改變其磁特性，再由控制其摩刷條件可改變其對液晶之預傾角大小及配向模式，因而可增加其應用範圍。本發明不僅製程手續簡便，並且與傳統之直流或交流電漿源設備共用亦同樣具有高透光度、硬度及絕緣性等特性。除了可降低其成本外，該透明磁性薄膜本身具有之磁性，更無須額外之配向處理程序即可達到非接觸式(Non-contact)多重區域(Multi-domain)配向之效果。
頂閘極型電晶體陣列基板
(2012-01-21)
鄭晃忠
;
黃昱智
;
楊柏宇
;
姜信銓
;
李懷安
一種頂閘極型電晶體陣列基板，包括一透明基板、一離子釋出層、一畫素陣列與一第一絕緣層。透明基板具有一平面，而離子釋出層配置於透明基板上，並全面性地覆蓋平面。畫素陣列配置於離子釋出層上，並包括多個電晶體與多個畫素電極。各個電晶體包括一源極、一汲極、一閘極與一金氧半導體層。汲極、源極與金氧半導體層皆配置於離子釋出層上，而這些畫素電極分別電性連接這些汲極。閘極配置於金氧半導體層的上方，而第一絕緣層配置於這些金氧半導體層與這些閘極之間。金氧半導體層接觸離子釋出層。離子釋出層能釋出多個離子至金氧半導體層。
System for producing the parameters of a bass-enhanced loudspeaker enclosure
(2012-01-24)
Bai Ming-Sian R.
;
Zhang Huan-Sheng
;
Chen Rong-Liang
A system for producing parameters for a bass-enhanced loudspeaker enclosure; meanwhile, a low-frequency extended frequency, a quality and quantity ratio and radius of a port need to be defined for the system. Also, the resonance frequency of a mechanical system and the quality and quantity of a mechanical system are fixed to obtain the parameters for the frequency ratio, the length of the duct and the cavity volume inside the device, etc. and to manufacture the bass-enhanced loudspeaker enclosure.
Reading device
(2012-01-24)
Sun Ching-Cherng
;
Yu Yeh-Wei
A reading device includes a spatial light modulator, a zoom lens set, an object lens, an image sensor, and an adjusting module. The spatial light modulator provides a reading beam. The zoom lens set forms the reading beam into a real image. The object lens focuses the real image onto a collinear holographic storage medium and thus produces a diffraction signal. The image sensor converts the diffraction signal into an electric signal. The adjusting module adjusts the optical magnification of the zoom lens set according to the quality of the diffraction signal.
System and method for measuring dispersion
(2012-01-24)
Jyu Siao-Shan
;
Lai Yin-Chieh
;
Liu Shiou-Fong
;
Hsiang Wei-Wei
;
Chang Hon-Chieh
A method for measuring dispersion in an optical fiber is provided and includes the following steps. A periodic wavelength variation pulse light signal is generated by a periodic frequency-swept pulse light source, in which the periodic wavelength variation pulse light signal has periodic wavelength variations. The periodic wavelength variation pulse light signal is transmitted into a test optical fiber. The periodic wavelength variation pulse light signal propagating through the test optical fiber is detected to generate a sensing signal. The sensing signal is transformed into an RF spectrum to obtain a slow periodic pulse timing variation of the periodic wavelength variation pulse light signal in accordance with the RF spectrum. A dispersion value of the test optical fiber is obtained in accordance with the slow periodic pulse timing variation. A system for measuring dispersion in a fiber is also disclosed herein.
Modeling frequency modulated responses of midbrain auditory neurons based on trigger features and artificial neural networks
(2012-01-24)
Chang, T. R.
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Chiu, T. W.
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Sun, X.
;
Poon, Paul W. F.
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生物科技學系
Frequency modulation (FM) is an important building block of communication signals for animals and human. Attempts to predict the response of central neurons to FM sounds have not been very successful, though achieving successful results could bring insights regarding the underlying neural mechanisms. Here we proposed a new method to predict responses of FM-sensitive neurons in the auditory midbrain. First we recorded single unit responses in anesthetized rats using a random FM tone to construct their spectro-temporal receptive fields (STRFs). Training of neurons in the artificial neural network to respond to a second random FM tone was based on the temporal information derived from the STRF. Specifically, the time window covered by the presumed trigger feature and its delay time to spike occurrence were used to train a finite impulse response neural network (FIRNN) to respond to this random FM. Finally we tested the model performance in predicting the response to another similar FM stimuli (third random FM tone). We found good performance in predicting the time of responses if not also the response magnitudes. Furthermore, the weighting function of the FIRNN showed temporal 'bumps' suggesting temporal integration of synaptic inputs from different frequency laminae. This article is part of a Special Issue entitled: Neural Coding. (C) 2011 Elsevier B.V. All rights reserved.
Combination of Molecular, Morphological, and Interfacial Engineering to Achieve Highly Efficient and Stable Plastic Solar Cells
(2012-01-24)
Chang, Chih-Yu
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Cheng, Yen-Ju
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Hung, Shih-Hsiu
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Wu, Jhong-Sian
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Kao, Wei-Shun
A flexible solar device showing exceptional air and mechanical stability is produced by simultaneously optimizing molecular structure, active layer morphology, and interface characteristics. The PFDCTBT-C8-based (see figure) devices with inverted architecture exhibited excellent power conversion efficiencies of 7.0% and 6.0% on glass and flexible substrates, respectively.
Probing annihilations and decays of low-mass galactic dark matter in IceCube DeepCore array: Track events
(2012-01-25)
Lee, Fei-Fan
;
Lin, Guey-Lin
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物理研究所
;
Institute of Physics
The deployment of DeepCore array significantly lowers IceCube's energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we calculate the track event rate in DeepCore array due to neutrino flux produced by annihilations and decays of galactic dark matter. We also calculate the background event rate due to the atmospheric neutrino flux for evaluating the sensitivity of DeepCore array to galactic dark matter signatures. Unlike previous approaches, which set the energy threshold for track events at around 50 GeV (this choice avoids the necessity of including the oscillation effect in the estimation of atmospheric background event rate), we have set the energy threshold at 10 GeV to take full advantage of DeepCore array. We compare our calculated sensitivity with those obtained by setting the threshold energy at 50 GeV. We conclude that our proposed threshold energy significantly improves the sensitivity of DeepCore array to the dark matter signature for m (chi) < 100 GeV in the annihilation scenario and m (chi) < 300 GeV in the decay scenario.
Diffusion barrier characteristics and shear fracture behaviors of eutectic PbSn solder/electroless Co(W,P) samples
(2012-01-25)
Pan, Hung-Chun
;
Hsieh, Tsung-Eong
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材料科學與工程學系
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Department of Materials Science and Engineering
Diffusion barrier characteristics, activation energy (E(a)) of IMC growth and bonding properties of amorphous and polycrystalline electroless Co(W,P) (termed as alpha-Co(W,P) and poly-Co(W,P)) to eutectic PbSn solder are presented. Intermetallic compound (IMC) spallation and an nano-crystalline P-rich layer were observed in PbSn/alpha-Co(W,P) samples subjected to liquid-state aging at 250 degrees C. In contrast, IMCs resided on the P-rich layer in PbSn/alpha-Co(W,P) samples subjected to solid-state aging at 150 degrees C. Thick IMCs neigh-boring to an amorphous W-rich layer was seen in PbSn/poly-Co(W,P) samples regardless of the aging type. alpha-Co(W,P) was found to be a sacrificial- plus stuffed-type barrier while poly-Co(W,P) is mainly a sacrificial-type barrier. The values of E(a)'s for PbSn/alpha-Co(W,P) and PbSn/poly-Co(W,P) systems were 338.6 and 167.5 kJ/mol, respectively. Shear test revealed the ductile mode dominates the failure in both alpha- and poly-Co(W,P) samples. Analytical results indicated the high P content in electroless layer might enhance the barrier capability but degrade the bonding strength. (C) 2011 Elsevier B.V. All rights reserved.
PHOTO TRANSISTOR
(2012-01-26)
ZAN HSIAO-WEN
;
MENG HSIN-FEI
;
TSAI CHUANG-CHUANG
;
CHEN WEI-TSUNG
;
CHAO YU-CHIANG
A phototransistor includes a substrate, a gate layer, a dielectric layer, an active layer, a source and a drain, and a light absorption layer. The gate layer is disposed on a top of the substrate, and the dielectric layer is disposed on a top of the gate layer. The active layer has a first bandgap and is disposed on a top of the dielectric layer, and the source and the drain are disposed on a top of the active layer. The light absorption layer has a second bandgap and is capped on the active layer, and the second bandgap is smaller than the first bandgap.
Self-aligned top-gate thin film transistors and method for fabricating same
(2012-01-26)
Zan Hsiao-Wen
;
Chen Wei-Tsung
;
Chou Cheng-Wei
;
Tsai Chuang-Chuang
A self-aligned top-gate thin film transistor and a fabrication method thereof. The method includes preparing a substrate having sequentially formed thereon an oxide semiconductor layer, a dielectric layer, and a metallic layer, wherein the oxide semiconductor layer includes first and second connecting regions that are not covered by the dielectric layer and the metallic layer thereon respectively, the first and second connecting regions having a property of a conductor after undergone a heating process or an ultraviolet irradiation; and a source electrode and a drain electrode formed on the substrate and connected to the first and second connecting regions, respectively. Therefore, the contact resistance of the first and second connecting regions can be reduced without the process of ion dopants as required by prior art techniques, thereby simplifying the manufacturing process. Also, the source electrode and the drain electrode can be exactly relocated and further increase performance of the device.
Gaming control using a wearable and wireless EEG-based brain-computer interface device with novel dry foam-based sensors
(2012-01-28)
Liao, Lun-De
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Chen, Chi-Yu
;
Wang, I-Jan
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Chen, Sheng-Fu
;
Li, Shih-Yu
A brain-computer interface (BCI) is a communication system that can help users interact with the outside environment by translating brain signals into machine commands. The use of electroencephalographic (EEG) signals has become the most common approach for a BCI because of their usability and strong reliability. Many EEG-based BCI devices have been developed with traditional wet- or micro-electro-mechanical-system (MEMS)-type EEG sensors. However, those traditional sensors have uncomfortable disadvantage and require conductive gel and skin preparation on the part of the user. Therefore, acquiring the EEG signals in a comfortable and convenient manner is an important factor that should be incorporated into a novel BCI device. In the present study, a wearable, wireless and portable EEG-based BCI device with dry foam-based EEG sensors was developed and was demonstrated using a gaming control application. The dry EEG sensors operated without conductive gel; however, they were able to provide good conductivity and were able to acquire EEG signals effectively by adapting to irregular skin surfaces and by maintaining proper skin-sensor impedance on the forehead site. We have also demonstrated a real-time cognitive stage detection application of gaming control using the proposed portable device. The results of the present study indicate that using this portable EEG-based BCI device to conveniently and effectively control the outside world provides an approach for researching rehabilitation engineering.
Intra-cavity stimulated emissions of photons in almost pure spin states without imposed nonreciprocity
(2012-01-30)
Chang, Shu-Wei
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光電工程學系
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Department of Photonics
We propose a chiral Fabry-Perot cavity in which only the cavity modes in almost pure spin (circular polarization) states lase in the presence of gain. In absence of imposed nonreciprocal environments and time-reversal symmetry breaking of emitter states to favor the emission of circularly-polarized photons, only the resonance of modes with a specific spin orientation remains in the cavity. We demonstrate a prototype of the cavity using distributed Bragg reflectors and cholesteric liquid crystals. This reciprocal cavity may provide a method to control the angular momentum state of emitters based on stimulated emissions. (C) 2012 Optical Society of America