Browsing by Issue Date, starting with "2015-01-08"

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RECEIVER AND RECEIVING METHOD FOR A COMBINERLESS LINC OFDM SYSTEM
(2015-01-08)
WU Wen Rong
;
CHENG Sheng-Lung
;
HSU Ying-Pei
A receiver and a receiving method for use in a LINC OFDM system are provided. The receiver receives a signal from a transmitter of the combinerless LINC OFDM system, generates a CP removed signal by removing a CP from the signal, generates a DFT signal by applying a DFT operation to the CP removed signal, generates a plurality of equalized symbols according to the DFT signal, generates a plurality of soft bits from the equalized symbols, generates a plurality of candidates regarding a transmitted bit sequence based on the soft bits by a list-Viterbi decoding algorithm, and decides an estimated transmitted bit sequence corresponding to the transmitted bit sequence from the candidates. The receiving method is able to perform the operations of the receiver.
Four-dimensional imaging of carrier interface dynamics in p-n junctions
(2015-01-09)
Najafi, Ebrahim
;
Scarborough, Timothy D.
;
Tang, Jau
;
Zewail, Ahmed
;
光電工程學系
The dynamics of charge transfer at interfaces are fundamental to the understanding of many processes, including light conversion to chemical energy. Here, we report imaging of charge carrier excitation, transport, and recombination in a silicon p-n junction, where the interface is well defined on the nanoscale. The recorded images elucidate the spatiotemporal behavior of carrier density after optical excitation. We show that carrier separation in the p-n junction extends far beyond the depletion layer, contrary to the expected results from the widely accepted drift-diffusion model, and that localization of carrier density across the junction takes place for up to tens of nanoseconds, depending on the laser fluence. The observations reveal a ballistic-type motion, and we provide a model that accounts for the spatiotemporal density localization across the junction.
Quantum criticality in a Kondo quantum dot coupled to helical edge states of interacting 2D topological insulators
(2015-01-09)
Chung, Chung-Hou
;
Silotri, Salman
;
電子物理學系
;
Department of Electrophysics
We investigate theoretically the quantum phase transition (QPT) between the one-channel Kondo (ICK) and two-channel Kondo (2CK) fixed points in a quantum dot coupled to helical edge states of interacting 2D topological insulators (2DTI) with Luttinger parameter 0 < K < 1. The model was studied by Law et al (2010 Phys. Rev. B 81 041305(R)), and was mapped onto an anisotropic two-channel Kondo model via bosonization. For K < 1, the strong coupling 2CK fixed point was argued to be stable for infinitesimally weak tunnelings between the dot and the 2DTI based on a simple scaling dimensional analysis (Law et al 2010 Phys. Rev. B 81 041305(R). We re-examine this model beyond the bare scaling dimension analysis via a one-loop renormalization group (RG) approach combined with bosonization and re-fermionization techniques near weak-coupling and strong-coupling (2CK) fixed points. We find for a fixed value of K < 1 that the 2CK fixed point can be unstable towards the 1CK fixed point and the system is expected to undergo a quantum phase transition between 1CK and 2CK fixed points with changing Kondo couplings. Our RG approach is controlled near K = 1. In general, this QPT can also occur upon tuning the Luttinger parameter K to a critical value K-c smaller than unity (0 < K-c < 1) for fixed Konodo couplings. The QPT in our model comes as a result of the combined Kondo and the helical Luttinger physics in 2DTI, and it serves as the first example of the 1CK-2CK QPT that is accessible by the controlled RG approach. We extract quantum critical and crossover behaviors from various thermodynamical quantities near the transition. Our results are robust against particle-hole asymmetry for 1/2 < K < 1.
The Index of Dry-Jet Wet Spinning for Polyacrylonitrile Precursor Fibers
(2015-01-10)
Wang, Tai-Yuan
;
Chang, Hsiao-Chuan
;
Chiu, Yu-Tsung
;
Tsai, Jia-Lin
;
機械工程學系
A new spinning index for a PAN precursor fiber is proposed that includes the viscosity of a spinning dope, the thermodynamic affinity, and the draw ratio during the spinning process. Through dry-jet wet spinning, six types of PAN precursor fibers with different spinning parameters, including solid content, solvent content in a bath, and draw ratio, were fabricated and analyzed with tensile tests, SEM, and XRD. The results show that the spinning index can reflect the mechanical properties of the fibers but is less indicative of crystallinity. Hence, the current spinning index is recommended for use as an indicator for the mechanical properties of PAN precursor fibers. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41265.
上橋式驅動電路
(2015-01-11)
陳宗麟
;
張翼
;
成維華
;
鄭泗東
;
鄭時龍
本發明係提供一上橋式驅動電路適用於上橋功率電晶體驅動，其包含一自舉式電路及一電位位準轉換器。在電位位準轉換器的設計中，利用二極體來限制其中的電晶體的汲極-源極電壓差，再利用電容來承受高電壓差。因此，驅動電路中不需要具高崩潰電壓的電晶體例如LDMOS。本發明可由一般的IC製程製作具高崩潰電壓的電容，因此所設計的驅動電路可整合於積體電路中。
用於顯示器之彩色畫素
(2015-01-11)
范士岡
;
邱誠樸
;
陳世強
一種用於顯示器之彩色畫素，包含：至少三個子畫素，每一個子畫素含有一個上載體、一個下載體、一個固定至該上載體之上電極、一個固定至該下載體之下電極、一個設置在該上及下電極之間的溶液，及多數個設置在該溶液內之粒子；其中，該等子畫素之粒子會在一特定驅動頻率下被電極化，且該等子畫素在顯示時可具有不同色彩；及該等子畫素之色彩分別透過該等子畫素之上載體、該等下載體、該等溶液或是該等粒子所提供。本發明之彩色畫素在應用至顯示器時，可顯示多樣且穩定的色彩變化。
丹磺醯衍生物之錯合物及其製法與應用
(2015-01-11)
王雲銘
;
林谷奎
一種丹磺醯衍生物之錯合物，是由下式(Ⅱ)所示： (II) 於式(Ⅱ)中，M、X、n及R1至R4的定義如說明書所述。本發明亦提供一種偵測一分析物中之過氧亞硝酸根離子的方法，包含使該分析物與一丹磺醯衍生物或該丹磺醯衍生物之錯合物反應，並量測所產生的螢光強度。本發明丹磺醯衍生物之錯合物可藉由量測螢光強度快速並專一性地偵測過氧亞硝酸根離子，且其不具有細胞毒性，並能有效偵測細胞中的過氧亞硝酸根離子。
服務啟動方法及系統
(2015-01-11)
林家瑜
;
陳昱嘉
;
王蒞君
;
曾煜棋
一種服務啟動方法及系統，此方法適用於包括感測器與資料擷取單元的電子裝置。此服務啟動方法包括下列步驟。首先，當感測器接收觸發訊號，判斷觸發訊號是否符合預設的觸發條件。若觸發訊號符合觸發條件，依據觸發條件判斷是否開啟資料擷取單元。當資料擷取單元開啟時，資料擷取單元接收輸入訊號。接著，辨識輸入訊號產生辨識資料。最後，判斷辨識資料是否符合預設的啟動條件，若判斷為是，啟動預設服務。
Vertical plasmonic resonance coupler
(2015-01-12)
Hsu, Yi-Jang
;
Lai, Yinchieh
;
光電工程學系
;
光電工程研究所
;
Department of Photonics
Efficient wavelength-selective coupling of lights between subwavelength plasmonic waveguides and free space is theoretically investigated. The idea is based on a new type of vertical resonance coupling devices built on plasmonic metal/insulator/metal (MIM)waveguides. The device structure consists of a vertical grating coupler in a resonance cavity formed by two distributed Bragg reflectors (DBRs). With the metal loss included, maximum coupling efficiency around 50% can be obtained at the 1550 nm wavelength with a filtering 3dB bandwidth around 20 nm (7nm for the lossless case), demonstrating the feasibility of the idea for achieving high efficiency wavelength-selective vertical coupling through optical resonance. By utilizing this coupler, a plasmonic add-drop device is proposed and theoretically demonstrated. This kind of compact wavelength selective coupling devices shall have the potential to open up a new avenue of photonics circuitry at nanoscale. (C) 2015 Optical Society of America
Borate moiety-contained linker and bio-sensing element containing the same
(2015-01-13)
Li Yaw-Kuen
;
Shen Mo-Yuan
;
Pien Yu-Ju
A borate moiety-contained linker and a bio-sensing element containing the same are disclosed. The borate moiety-contained linker can be used to modify a sensing molecule and connect the sensing molecule to a substrate to form the bio-sensing element.
Method for fabricating thin-film transistor
(2015-01-13)
Lin Horng-Chih
;
Lyu Rong-Jhe
A method for fabricating a thin-film transistor is disclosed. Firstly, a patterned dielectric mask structure with a bottom thereof having a gate dielectric layer is formed on a gate-stacked structure so that the gate dielectric layer covers a gate of the gate-stacked structure. Top surface of the patterned dielectric mask structure has at least two openings. A semiconductor layer is formed on the gate-stacked structure via the openings by a sputtering method. The semiconductor layer comprises a channel above the gate, a source and a drain below the openings. The channel has a thickness which sequentially decreases from edge to center.
Enhanced Thermoelectric Performance of PEDOT:PSS Flexible Bulky Papers by Treatment with Secondary Dopants
(2015-01-14)
Mengistie, Desalegn A.
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Chen, Chang-Hsiao
;
Boopathi, Karunakara M.
;
Pranoto, Ferry W.
;
Li, Lain-Jong
For inorganic thermoelectric materials, Seebeck coefficient and electrical conductivity are interdependent, and hence optimization of thermoelectric performance is challenging. In this work we show that thermoelectric performance of PEDOT:PSS can be enhanced by greatly improving its electrical conductivity in contrast to inorganic thermoelectric materials. Free-standing flexible and smooth PEDOT:PSS bulky papers were prepared using vacuum-assisted filtration. The electrical conductivity was enhanced to 640, 800, 1300, and 1900 S cm(-1) by treating PEDOT:PSS with ethylene glycol, polyethylene glycol, methanol, and formic acid, respectively. The Seebeck coefficient did not show significant variation with the tremendous conductivity enhancement being 21.4 and 20.6 mu V K-1 for ethylene glycol- and formic acid-treated papers, respectively. This is because secondary dopants, which increase electrical conductivity, do not change oxidation level of PEDOT. A maximum power factor of 80.6 mu W m(-1) K-2 was shown for formic acid-treated samples, while it was only 29.3 mu W m(-1) K-2 for ethylene glycol treatment. Coupled with intrinsically low thermal conductivity of PEDOT:PSS, ZT approximate to 0.32 was measured at room temperature using Harman method. We investigated the reasons behind the greatly enhanced thermoelectric performance.
Highly Thermal Stable and Efficient Organic Photovoltaic Cells with Crosslinked Networks Appending Open-Cage Fullerenes as Additives
(2015-01-14)
Chen, Chih-Ping
;
Huang, Chien-Yu
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Chuang, Shih-Ching
;
應用化學系
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Department of Applied Chemistry
Highly thermal stable organic bulk heterojunction (OBHJ) photovoltaic cells are demonstrated with crosslinkable open-cage fullerenes (COF) as additives in the active layer. Partial incorporation of COF, approximate to 10-15 wt% with weight ratio of P3HT:PC61BM = 1:0.9, builds up three-dimensional local borders upon heating treatment at 150 degrees C for 10 min. This process induces crosslinking chemical reaction through activating the styryl moiety in COF and reduces phase aggregation rates of fullerenes materials. Supported by statistics of devices degradation data analysis and optical microscopy study, the devices with COF show longer lifetime with keeping their efficiency (t = 144 h) under accelerated heating test at 150 degrees C, while PCE of normal devices without COF drop dramatically. These results demonstrate that the thermally crosslinkable COF is an excellent additive for highly thermal stable and durable OPVs applications.
Zinc Oxide Nanowire-Poly(Methyl Methacrylate) Dielectric Layers for Polymer Capacitive Pressure Sensors
(2015-01-14)
Chen, Yan-Sheng
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Hsieh, Gen-Wen
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Chen, Shih-Ping
;
Tseng, Pin-Yen
;
Wang, Cheng-Wei
Polymer capacitive pressure sensors based on a dielectric composite layer of zinc oxide nanowire and poly(methyl methacrylate) show pressure sensitivity in the range of 2.63 x 10(-3) to 9.95 x 10(-3) cm(2) gf(-1). This represents an increase of capacitance change by as much as a factor of 23 over pristine polymer devices. An ultralight load of only 10 mg (corresponding to an applied pressure of similar to 0.01 gf cm(-2)) can be clearly recognized, demonstrating remarkable characteristics of these nanowire-polymer capacitive pressure sensors. In addition, optical transmittance of the dielectric composite layer is approximately 90% in the visible wavelength region. Their low processing temperature, transparency, and flexible dielectric film makes them a highly promising means for flexible touching and pressure-sensing applications.
Novel Reddish-Orange-Emitting BaLa2Si2S8:Eu2+ Thiosilicate Phosphor for LED Lighting
(2015-01-14)
Lee, Szu-Ping
;
Chan, Ting-Shan
;
Chen, Teng-Ming
;
應用化學系
;
應用化學系分子科學碩博班
A novel reddish-orange-emitting BaLa2Si2S8:Eu2+ thiosilicate was prepared in a sealed fused silica ampule and its crystal structure was refined using Rietveld methods. The BaLa2Si2S8:Eu2+ phosphor is excitable over a broad range from UV to blue (350-450 nm) and generated a reddish-orange broadband emission peaking at 645 nm with a quantum efficiency of similar to 24%. The thermal luminescence quenching of BaLa2Si2S8:Eu2+ was investigated over the range 25 to 150 degrees C. This phosphor was utilized to incorporate with two commercially available phosphors, blue BaMgAl10O17:Eu2+ and green (Ba,Sr)(2)SiO4:Eu2+, and a near-UV LED chip (405 nm), a white light with Ra of similar to 94 was obtained.
D-s -> eta,eta ' semileptonic decay form factors with disconnected quark loop contributions
(2015-01-14)
Bali, Gunnar S.
;
Collins, Sara
;
Duerr, Stephan
;
Kanamori, Issaku
;
物理研究所
We calculate for the first time the form factors of the semileptonic decays of the D-s meson to eta and eta ' using lattice techniques. As a by-product of the calculation we obtain the masses and leading distribution amplitudes of the eta and eta' mesons. We use N-f = 2 + 1 nonperturbatively improved clover fermions on configurations with a lattice spacing a similar to 0.075 fm. We are able to obtain clear signals for relevant matrix elements, using several noise reduction techniques, for both the connected and the disconnected contributions. This includes a new method for reducing the variance of pseudoscalar disconnected two-point functions. At zero momentum transfer, we obtain for the scalar form factors, vertical bar f(0)(Ds ->eta)vertical bar = 0.564(11) and vertical bar f(0)(Ds ->eta')vertical bar = 0.437(18) at M-pi approximate to 470 MeV, as well as vertical bar f(0)(Ds ->eta)vertical bar = 0.542(13) and vertical bar f(0)(Ds ->eta')vertical bar = 0.404(25) at M-pi approximate to 370 MeV, w here the errors are statistical only.
Significantly Improved Luminescence Properties of Nitrogen-Polar (000(1over bar>)over-bar) InGaN Multiple Quantum Wells Grown by Pulsed Metalorganic Chemical Vapor Deposition
(2015-01-14)
Song, Jie
;
Chang, Shih-Pang
;
Zhang, Cheng
;
Hsu, Ta-Cheng
;
Han, Jung
We have demonstrated nitrogen-polar (000 (1) over bar) (N-polar) InGaN multiple quantum wells (MQWs) with significantly improved luminescence properties prepared by pulsed metalorganic chemical vapor deposition. During the growth of InGaN quantum wells, Ga and N sources are alternately injected into the reactor to alter the surface stoichiometry. The influence of flow duration in pulsed growth mode on the luminescence properties has been studied. We find that use of pulsed-mode creates a high density of hexagonal mounds with an increased InGaN growth rate and enhanced In composition around screw-type dislocations, resulting in remarkably improved luminescence properties. The mechanism of enhanced luminescence caused by the hexagonal mounds is discussed. Luminescence properties of N-polar InGaN MQWs grown with short pulse durations have been significantly improved in comparison with a sample grown by a conventional continuous growth method.
Chiral Hall effect and chiral electric waves
(2015-01-14)
Pu, Shi
;
Wu, Shang-Yu
;
Yang, Di-Lun
;
物理研究所
;
丘成桐中心
We investigate the vector and axial currents induced by external electromagnetic fields and chemical potentials in chiral systems at finite temperature. Similar to the normal Hall effect, we find that an axial Hall current is generated in the presence of the electromagnetic fields along with an axial chemical potential, which may be dubbed as the "chiral Hall effect" (CHE). The CHE is related to the interactions of chiral fermions and exists with a nonzero axial chemical potential. We argue that the CHE could lead to nontrivial charge distributions at different rapidity in asymmetric heavy ion collisions. Moreover, we study the chiral electric waves led by the fluctuations of the vector and axial chemical potentials along with the chiral electric separation effect, where a density wave propagates along the applied electric field. Combining with the normal/chiral Hall effects, the fluctuations of chemical potentials thus result in Hall density waves. The Hall density waves may survive even at zero chemical potentials and become nondissipative. We further study the transport coefficients including the Hall conductivities, damping times, wave velocities, and diffusion constants of chiral electric waves in a strongly coupled plasma via the AdS/CFT correspondence.
Highly Effective Field-Effect Mobility Amorphous InGaZnO TFT Mediated by Directional Silver Nanowire Arrays
(2015-01-14)
Liu, Hung-Chuan
;
Lai, Yi-Chun
;
Lai, Chih-Chung
;
Wu, Bing-Shu
;
Zan, Hsiao-Wen
In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.
20150115第三期目錄
(2015-01-15)
編輯室
;
Shing-Tung Yau Center
;
丘成桐中心
編輯曲線數理簡訊 [專題] 數學教育與十二年國教教改的矛盾 [數] 「克萊恩瓶」主題變奏曲 [理] 數學在分子生物學中的有效性 [人] 漫步在馮諾曼花園　天才的花朵 [文] 數學家，出來吧！　誤入歧途的數學師資培育 CCSS餘波蕩漾　近年美國媒體的數學教育論戰別聽威爾森胡扯 [書評] 推薦《一個數學家的嘆息》白臉：嘆息之後黑臉：數學教育的兩難