Browsing by Issue Date, starting with "2014-02-04"

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Apparatus and method of processing polynomials
(2014-02-04)
Lin Yi-Min
;
Yang Chi-Heng
;
Chang Hsie-Chia
;
Lee Chen-Yi
An apparatus of processing polynomials includes at least one reconfigurable module and an encoder controller. The reconfigurable module includes a plurality of linear feedback shift registers. The encoder controller can control the reconfigurable module to factor a generator polynomial into a factorial polynomial. In the reconfigurable module, the linear feedback shift registers can register a plurality of factors of the factorial polynomial respectively.
Mimic the optical conductivity in disordered solids via gauge/gravity duality
(2014-02-05)
Sun, Jia-Rui
;
Wu, Shang-Yu
;
Zhang, Hai-Qing
;
物理研究所
;
Institute of Physics
We study the optical conductivity in a (2 + 1)-dimensional non-relativistic field theory holographically dual to a (3 + 1)-dimensional charged Lifshitz black brane within the Einstein-Maxwell-dilaton theory. Surprisingly, we find that the optical AC conductivity satisfies the nontrivial (non-)power law scaling in the high frequency regime rather than approaching to a constant when the dynamical critical exponent z > 1, which is qualitatively similar to those in various disordered solids in condensed matter systems. Besides, this (non-)power law scaling behavior shows some universality, which is robust against the temperatures. We argue that the peculiar scaling behavior of AC conductivity may stem from the couplings of the dilaton field with the gauge fields and also the logarithmic behavior near the boundary in the Lifshitz spacetime. (C) 2014 The Authors. Published by Elsevier B.V. All rights reserved.
In Situ Ultralow-Frequency Raman Tracking of the Polymorphic Transformation of Crystalline 1,1 '-Binaphthyl
(2014-02-06)
Chang, Chun-Fu
;
Wang, Szu-Cheng
;
Shigeto, Shinsuke
;
應用化學系
;
Department of Applied Chemistry
Extremely low-frequency (LF) Raman spectroscopy that allows for fast access to lattice vibrations with little hindrance of immense Rayleigh scattering was used to track in situ thermally induced polymorphic transformation of crystalline 1,1'-binaphthyl (BN), a fundamental structural unit of specific chiral ligands. BN occurs in two conformational polymorphs, cisoid and transoid forms, with the former being a racemate and the latter being a conglomerate of chiral crystals. Observed LF Raman spectra (from 200 cm(-1) down to similar to 5 cm(-1), equivalent to 0.15 THz), which arise predominantly from lattice vibrations, show markedly different features between the cisoid and transoid forms, making it possible to study their phase transition. A series of LF Raman spectra measured with slow heating of microcrystalline BN reveal that, in contrast to previous studies, the monoclinic cisoid form transforms directly to the tetragonal transoid form in the solid state without formation of any intermediate phase. The present approach is applicable to various phase transition systems, including pharmaceutical compounds, liquid crystals, and polymer films, which conventional X-ray diffraction analysis may not be able to investigate.
Effects of Current-Induced Forces on Pt-Benzene-Pt Single-Molecule Junctions
(2014-02-06)
Hsu, Bailey C.
;
Amanatidis, Ilias
;
Liu, Wei-Lin
;
Tseng, Allen
;
Chen, Yu-Chang
From first-principles approaches, we investigate the torque exerted by the current-induced forces in a highly asymmetric molecular junction, where the benzene molecule is directly connected to the platinum electrodes. We observe that the curved flow of the current streamline around the tilted molecule can induce a net torque, which tends to rotate the benzene molecule, much like the way a stream of water rotates a waterwheel. The magnitude and direction of the net torque are determined by the detailed current density flowing through the molecular junction. Such an asymmetric molecular junction could offer an experimentally practical system for the exploration of an electrically controllable single-molecule motor. The idea given above is also supported by a simple physical model based on the Landauer-Buttiker formula in the tight-binding framework.
Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos
(2014-02-06)
Lai, Kwang-Chang
;
Lin, Guey-Lin
;
Liu, Tsung-Che
;
物理研究所
;
Institute of Physics
Observation of ultrahigh energy astrophysical neutrinos and identification of their flavors have been proposed for future neutrino telescopes. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. The flavor transition mechanisms are well classified with our model-independent parametrization. We find that a new parameter R equivalent to phi(e)/(phi(mu) + phi(tau)) can probe directly the flavor transition in the framework of our model-independent parametrization, without the assumption of the nu(mu)-nu(tau) symmetry. A few flavor-transition models are employed to test our parametrization with this new observable. The observational constraints on flavor transition mechanisms by the new observable are discussed through our model- independent parametrization.
Synthesis and Supramolecular Assembly of Pentacyclic Dithienofluorene and Diselenophenofluorene Derivatives
(2014-02-07)
Lee, Chia-Hao
;
Lai, Yu-Ying
;
Cheng, Sheng-Wen
;
Cheng, Yen-Ju
;
應用化學系
2,7-Diiodo-3,6-dibromofluorene and 2,7-dichloro-3,6-dibromofluorene have been successfully synthesized. The two key intermediates enable us to implement a regioselective Sonogashira reaction followed by intramolecular thiolate/acetylene cyclization, forming two regiospecific pentacyclic dithieno[2,3-b:7,6-b']fluorene (2,7-DTF) and dithieno[3,2-b:6,7-b']fluorene (3,6-DTF) isomeric molecules, respectively. By using a similar strategy, selenophene-based diselenopheno[2,3-b:7,6-b']fluorene (2,7-DSF) as well as diselenopheno[3,2-b:6,7-b'] fluorene (3,6-DSF) were also prepared. The isomeric and sulfur/selenium effects determine the optical, electrochemical, and orbital properties. X-ray crystallography revealed that 2,7-DTF and 3,6-DTF molecules assemble into supramolecular helical structures.
Nucleobase-grafted supramolecular polymers for tuning the surface properties
(2014-02-07)
Lin, I. -Hong
;
Cheng, Chih-Chia
;
Li, Ke-Fong
;
Chen, Jem-Kun
;
Chiu, Chih-Wei
Nucleobase-grafted polycaprolactone has been prepared which exhibits amorphous nature, rapid photoresponse and controlled surface properties in the solid state owing to the formation of uracil-diamidopyridine (U-DAP) pairs by induced physical cross-linking. In addition, they can self-organize to alter material behavior with light, switching both optical and thermal properties. Remarkable changes in the surface morphology and the contact angle with water were also observed.
Misfit strain driven cation inter-diffusion across an epitaxial multiferroic thin film interface
(2014-02-07)
Krishnan, P. S. Sankara Rama
;
Morozovska, Anna N.
;
Eliseev, Eugene A.
;
Ramasse, Quentin M.
;
Kepaptsoglou, Demie
Cation intermixing at functional oxide interfaces remains a highly controversial area directly relevant to interface-driven nanoelectronic device properties. Here, we systematically explore the cation intermixing in epitaxial (001) oriented multiferroic bismuth ferrite (BFO) grown on a (001) lanthanum aluminate (LAO) substrate. Aberration corrected dedicated scanning transmission electron microscopy and electron energy loss spectroscopy reveal that the interface is not chemically sharp, but with an intermixing of similar to 2 nm. The driving force for this process is identified as misfit-driven elastic strain. Landau-Ginzburg-Devonshire-based phenomenological theory was combined with the Sheldon and Shenoy formula in order to understand the influence of boundary conditions and depolarizing fields arising from misfit strain between the LAO substrate and BFO film. The theory predicts the presence of a strong potential gradient at the interface, which decays on moving into the bulk of the film. This potential gradient is significant enough to drive the cation migration across the interface, thereby mitigating the misfit strain. Our results offer new insights on how chemical roughening at oxide interfaces can be effective in stabilizing the structural integrity of the interface without the need for misfit dislocations. These findings offer a general formalism for understanding cation intermixing at highly strained oxide interfaces that are used in nanoelectronic devices. (C) 2014 AIP Publishing LLC.
Intramolecular Interactions of a Phenyl/Perfluorophenyl Pair in the Formation of Supramolecular Nanofibers and Hydrogels
(2014-02-10)
Hsu, Shu-Min
;
Lin, Yu-Chun
;
Chang, Jui-Wen
;
Liu, Yu-Hao
;
Lin, Hsin-Chieh
A new system for the incorporation of a phenyl/perfluorophenyl pair in the structure of a peptide hydrogelator was developed. The strategy is based on the idea that the integration of an end-capped perfluorophenyl group and a phenylalanine with a phenyl moiety in the side chain forms an intramolecular phenyl/perfluorophenyl pair, which can be used to promote the formation of the supramolecular nanofibers and hydrogels. This work illustrates the importance of structure-hydrogelation relationship and provides new insights into the design of self-assembly nanobiomaterials.
High-resistance liquid-crystal lens array for rotatable 2D/3D autostereoscopic display
(2014-02-10)
Chang, Yu-Cheng
;
Jen, Tai-Hsiang
;
Ting, Chih-Hung
;
Huang, Yi-Pai
;
光電工程學系
A 2D/3D switchable and rotatable autostereoscopic display using a high-resistance liquid-crystal (Hi-R LC) lens array is investigated in this paper. Using high-resistance layers in an LC cell, a gradient electric-field distribution can be formed, which can provide a better lens-like shape of the refractive-index distribution. The advantages of the Hi-R LC lens array are its 2D/3D switchability, rotatability (in the horizontal and vertical directions), low driving voltage (similar to 2 volts) and fast response (similar to 0.6 second). In addition, the Hi-R LC lens array requires only a very simple fabrication process. (C) 2014Optical Society of America
Heterodyne moire surface profilometry
(2014-02-10)
Chang, Wei-Yao
;
Hsu, Fan-Hsi
;
Chen, Kun-Huang
;
Chen, Jing-Heng
;
Hsu, Ken Y.
In this study, a novel moire fringe analysis technique is proposed for measuring the surface profile of an object. After applying a relative displacement between two gratings at a constant velocity, every pixel of CMOS camera can capture a heterodyne moire signal. The precise phase distribution of the moire fringes can be extracted using a one-dimensional fast Fourier transform (FFT) analysis on every pixel, simultaneously filtering the harmonic noise of the moire fringes. Finally, the surface profile of the tested objected can be generated by substituting the phase distribution into the relevant equation. The findings demonstrate the feasibility of this measuring method, and the measurement error was approximately 4.3 mu m. The proposed method exhibits the merits of the Talbot effect, projection moire method, FFT analysis, and heterodyne interferometry. (C) 2014 Optical Society of America
Switching mechanism of double forming process phenomenon in ZrOx/HfOy bilayer resistive switching memory structure with large endurance
(2014-02-10)
Huang, Chun-Yang
;
Huang, Chung-Yu
;
Tsai, Tsung-Ling
;
Lin, Chun-An
;
Tseng, Tseung-Yuen
In this Letter, the mechanism of double forming process phenomenon revealing in ZrO2/HfO2 bilayer resistive random access memory structure is investigated. This phenomenon caused by the formation of TiON interfacial layer can be well explained by using the energy band diagram. The TiON interfacial layer will be a tunneling barrier during the first forming process when a negative voltage applied on the device, while it will breakdown when applying a positive voltage. Besides, due to the double forming process, an asymmetric conductive filament with narrower size at ZrO2/HfO2 interface is formed in the device. The point for formation and rupture of the conductive filament can be confined at the ZrO2/HfO2 interface, and it will suppress the consumption of oxygen ions during endurance test. Therefore, high speed (40 ns) and large endurance (10(7) cycles) characteristics are achieved in this device structure. (C) 2014 AIP Publishing LLC.
Thermodielectric generation of defect modes in a photonic liquid crystal
(2014-02-10)
Hsiao, Yu-Cheng
;
Wang, Hsiao-Tsung
;
Lee, Wei
;
光電學院
;
College of Photonics
Photonic defect modes induced by in situ formation of an ill-defined defect layer is demonstrated in a cholesteric liquid crystal (CLC). The local deformation of the one-dimensionally periodic helical structure is achieved by means of the thermodielectric effect, which alters the pitch in the middle of the cholesteric structure. The defect-mode peak in the photonic band gap appears in the transmission spectrum only when the incident circularly polarized light has the same handedness as that of the CLC structure. The wavelength of the deformation-induced defect mode can be tuned upon varying the dielectric heating power by simply applying a frequency-modulated voltage. (C) 2014 Optical Society of America
Anomaly secure detection methods by analyzing dynamic characteristics of the network traffic in cloud communication?
(2014-02-10)
Xiong, Wei
;
Hu, Hanping
;
Xiong, Naixue
;
Yang, Laurence T.
;
Peng, Wen-Chih
Cloud computing represents a new paradigm where computing resources are offered as services in the world via communication Internet. As many new types of attacks are arising at a high frequency, the cloud computing services are exposed to an increasing amount of security threats. To reduce security risks, two approaches of the network traffic anomaly detection in cloud communications have been presented, which analyze dynamic characteristics of the network traffic based on the synergetic neural networks and the catastrophe theory. In the former approach, a synergetic dynamic equation with a group of the order parameters is used to describe the complex behaviors of the network traffic system in cloud communications. When this equation is evolved, only the order parameter determined by the primary factors can converge to 1. Then, the anomaly can be detected. In the latter approach; a catastrophe potential function is introduced to describe the catastrophe dynamic process of the network traffic in cloud communications. When anomalies occur, the state of the network traffic will deviate from the normal one. To assess the deviation, an index named as catastrophe distance is defined. The network traffic anomaly can be detected by the value of this index. We evaluate the performance of these two approaches using the standard Defense Advanced Research Projects Agency data sets. Experimental results show that our approaches can effectively detect the network traffic anomaly and achieve the high detection probability and the low false alarms rate. (C) 2013 Published by Elsevier Inc.
Spectral Measurement of Electron Antineutrino Oscillation Amplitude and Frequency at Daya Bay
(2014-02-10)
An, F. P.
;
Balantekin, A. B.
;
Band, H. R.
;
Beriguete, W.
;
Bishai, M.
A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos ((v) over bar (e)) from six 2.9 GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2) 2 theta(13) = 0.090(-0.009)(+0.008) and the first direct measurement of the (v) over bar (e) mass-squared difference vertical bar Delta m(ee)(2)vertical bar = (2.59(-0.20)(+0.19) x 10(-3) eV(2)) is obtained using the observed (v) over bar (e) rates and energy spectra in a three-neutrino framework. This value of vertical bar Delta m(ee)(2)vertical bar eejis consistent with vertical bar Delta m(mu mu)(2)vertical bar measured by muon neutrino disappearance, supporting the three-flavor oscillation model.
Flexible-textured polydimethylsiloxane antireflection structure for enhancing omnidirectional photovoltaic performance of Cu(In,Ga)Se-2 solar cells
(2014-02-10)
Kuo, Shou-Yi
;
Hsieh, Ming-Yang
;
Han, Hau-Vei
;
Lai, Fang-I
;
Chuang, Tsung-Yeh
Because of the Sun's movement across the sky, broadband and omnidirectional light harvesting is a major development in photovoltaic technology. This study reports the fabrication and characterization of flexible-textured polydimethylsiloxane ( PDMS) film on Cu(In,Ga)Se-2 (CIGS) solar cells, which is one of the simplest and cheapest peel-off processes for fabricating a three-dimensional structure. A cell containing a textured PDMS film enhanced the short-circuit current density from 22.12 to 23.93 mA/cm(2) in a simulated one-sun scenario. The omnidirectional antireflection of CIGS solar cells containing various PDMS films is also investigated. This study uses an angle-resolved reflectance spectroscope to investigate the omnidirectional and broadband optical properties of the proposed PDMS film. This improvement in light harvesting is attributable to the scattering of the PDMS film and the gradual refractive index profile between the PDMS microstructures and air. The flexible-textured PDMS film is suitable for creating an antireflective coating for a diverse range of photovoltaic devices. (C) 2014 Optical Society of America
Suspended GaN-based band-edge type photonic crystal nanobeam cavities
(2014-02-10)
Wu, Tzeng Tsong
;
Chen, Hao Wen
;
Lan, Yu Pin
;
Lu, Tien Chang
;
Wang, Shing Chung
We demonstrated GaN-based photonic crystal (PC) nanobeam cavities by using the e-beam lithography and the suspended nanobeams were realized by focused-ion beam (FIB) milling. One resonant mode was clearly observed at 411.7 nm at 77K by optical pumping. The quality factor was measured to be to 7.4 x 10(2). Moreover, the degree of polarization value was measured to be 40%. The temperature-dependent characteristics were measured and discussed, which unambiguously demonstrated that the observed resonant peak originated from the band-edge mode of the one-dimensional PC nanobeam. (C) 2014 Optical Society of America
用於多用戶多輸入多輸出正交分頻多工系統的資源配置方法及其裝置
(2014-02-11)
王蒞君
;
葉俥榮
本發明的示範實施例提供了一種用於多用戶多輸入多輸出正交分頻多工系統的資源配置方法及其裝置。此多用戶多輸入多輸出正交分頻多工系統具有多個用戶和子通道。此多個子通道根據容量比率限制以及排程規則被指定給此多個用戶，接著再根據此多用戶多輸入多輸出正交分頻多工系統的極限功率決定每一個用戶的功率。其中，被指定給某個用戶的各個子通道之間的分配功率值是相同的。另外，排程規則可以是極大－極小或極大比率總和規則，而且子通道的配置方式可以為用戶導向的或者子通道導向。
光學全像資料讀取系統
(2014-02-11)
孫慶成
;
余業緯
;
吳啟守
;
林烜輝
本發明係關於一種光學全像資料讀取系統，係配合一記錄裝置，用於讀取儲存於記錄裝置之資料，該系統包括：一光發射裝置，用以發射一讀取光束至記錄裝置之複數個記錄位置以分別產生複數個反射光束，其中該等記錄位置係對應至記錄裝置表面一特定位置，並分別位於一預定深度；一感測裝置，係接收該等反射光束，且該等反射光束分別成像於感測裝置之不同位置；以及一控制裝置，係分別與光發射裝置及感測裝置耦合，以控制光發射裝置，並將該等反射光束於感測裝置的複數個成像對應轉換為複數個訊號，以讀取出記錄於記錄裝置上之資料。
倒置式有機太陽能元件及其製作方法
(2014-02-11)
陳方中
;
吳志力
;
洪毅
本發明係有關於一種倒置式有機太陽能元件及其製作方法，其中，倒置式有機太陽能元件係包括：一基板；一第一電極，係位於基板上；一有機主動層，係位於第一電極上；一光學間隙物，其包括一緩衝層、以及一光學介面層，緩衝層係位於有機主動層上，而光學介面層係層疊於緩衝層上，使緩衝層位於有機主動層與光學介面間；以及一第二電極，係位於光學間隙物上。藉由設置此適當厚度之光學間隙物，可增加有機主動層光的吸收，進而提升有機太陽能元件之能量轉換效率。