Browsing by Issue Date, starting with "2013-10-23"

Now showing 1 - 20 of 30318

Improvement of optical transmittance and electrical properties for the Si quantum dot-embedded ZnO thin film
(2013-10-23)
Kuo, Kuang-Yang
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Liu, Chuan-Cheng
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Huang, Pin-Ruei
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Hsu, Shu-Wei
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Chuang, Wen-Ling
A Si quantum dot (QD)-embedded ZnO thin film is successfully fabricated on a p-type Si substrate using a ZnO/Si multilayer structure. Its optical transmittance is largely improved when increasing the annealing temperature, owing to the phase transformation from amorphous to nanocrystalline Si QDs embedded in the ZnO matrix. The sample annealed at 700A degrees C exhibits not only high optical transmittance in the long-wavelength range but also better electrical properties including low resistivity, small turn-on voltage, and high rectification ratio. By using ZnO as the QDs' matrix, the carrier transport is dominated by the multistep tunneling mechanism, the same as in a n-ZnO/p-Si heterojunction diode, which clearly differs from that using the traditional matrix materials. Hence, the carriers transport mainly in the ZnO matrix, not through the Si QDs. The unusual transport mechanism using ZnO as matrix promises the great potential for optoelectronic devices integrating Si QDs.
Ab Initio Chemical Kinetics for SiH2 + Si2H6 and SiH3 + Si2H5 Reactions and the Related Uninnolecular Decomposition of Si3H8 under a-Si/H CVD Conditions
(2013-10-24)
Raghunath, P.
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Lin, M. C.
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應用化學系
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Department of Applied Chemistry
The kinetics and mechanisms for SiH2 + Si2H6 and SiH3 + Si2H5 reactions and the related unimolecular decomposition of Si3H8 have been investigated by ab initio molecular orbital theory based on the QCISD(T)/CBS//QCISD/6-311++G(d,p) method in conjunction with quantum statistical variational Rice-Ramsperger-Kassel-Marcus (RR.KM) calculations. For the barrierless radical association processes, their variational transition states have been characterized by the CASPT2//CASSCF method. The species involved in the study are known to coexist under CVD conditions. The results show that the association reaction of SiH2 and Si2H6 producing Si3H8 occurs by insertion via its lowest-energy path forming a loose hydrogen-bonding molecular complex with 8.3 kcal/mol binding energy; the reaction is exothermic by 55.0 kcal/mol. The chemically activated Si3H8 adduct can fragment by several paths, producing SiH4 + SiH3SiH (-0.7 kcal/mol), Si(SiH3)(2) + H-2 (-1.4 kcal/mol), and SiH3SiH2SiH + Hy (-1.4 kcal/mol). The predicted enthalpy changes as given agree well with available thermochemical data. Three other decomposition channels of Si3H8 occurring by Si-H or Si-Si breaking were found to be highly endothermic, and the reactions take place without a well-defined barrier. The heats of formation of Si3H8, SiH2SiH, Si2H4, n-Si3H7, Si(SiH3)(2), and SiH3SiH2SiH have been predicted and found to be in close agreement with those available data in the literature. The product branching rate constants for SiH2 + Si2H6 and SiH3 + Si2H3 reactions and the thermal unimolecular decomposition of Si3H8 for all low-energy paths have been calculated with multichannel variational RRKM theory covering varying P,T conditions typically employed in PECVD and Cat-CVD processes for hydrogenated amorphous silicon (a-Si/H) film growth. The results were also found to be in good agreement with available kinetic data. Our kinetic results may be employed to model and control very large-area a-Si/H film growth for a new generation of solar cell applications.
Quantum chemical calculation of intramolecular vibrational redistribution and vibrational energy transfer of water clusters
(2013-10-24)
Niu, Y. L.
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Pang, R.
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Zhu, C. Y.
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Hayashi, M.
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Fujimura, Y.
In present letter the adiabatic approximation is applied to the intramolecular vibrational redistribution (IVR) of water clusters. The isotope, blocking and cluster-size effects are investigated. This letter also examines the assumption associated with the transition state theory applied to unimolecular reactions; that is, IVR is assumed to be completed before the reaction takes place. For this purpose, we choose to study (H2O)(2)H+ -> H2O+ H3O+, and (H2O)(2) -> 2H(2)O processes. In molecular clusters, the vibrational excitation energy transfer between different normal modes has been observed. This will also be investigated for the deuterated species of (HOD)(2)H+. (C) 2013 Elsevier B.V. All rights reserved.
Ionization/dissociation processes of methyl-substituted derivates of cyclopentanone in intense femtosecond laser field
(2013-10-24)
Wang, Qiaoqiao
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Dyakov, Yuri A.
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Wu, Di
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Zhang, Dongdong
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Jin, Mingxing
Ionization and dissociation of 2- and 3-methyl cyclopentanones have been investigated in molecular beams by their irradiation with intense 394 and 788 nm laser fields with pulse duration of 90 fs and intensity of 3 x 10(13)-4 x 10(14) W/cm(2). The analysis of the resulting mass spectra allowed us to discern the effects of methyl substitution and its position on the outcome of ionization/dissociation processes induced by the intense femtosecond laser field. Generalized Keldysh-Faisal-Reiss (g-KFR) and ab initio G3(MP2, CCSD)//B3LYP/6-31G*/RRKM theoretical calculations helped to uncover the formation mechanism of major ionic fragments observed in the mass spectra including C5H10+, C4H6O+, C3H3O+, C3H4O+, C3Hx+, and C2Hx+. (C) 2013 Elsevier B.V. All rights reserved.
Hypochlorous acid turn-on boron dipyrromethene probe based on oxidation of methyl phenyl sulfide
(2013-10-24)
Liu, Shi-Rong
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Vedamalai, Mani
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Wu, Shu-Pao
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應用化學系
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Department of Applied Chemistry
A boron dipyrromethene (BODIPY)-based fluorometric probe, HCS, has been successfully developed for the highly sensitive and selective detection of hypochlorous acid (HOCl). The probe is based on the specific HOCl-promoted oxidation of methyl phenyl sulfide. The reaction is accompanied by a 160-fold increase in the fluorescent quantum yield (from 0.003 to 0.480). The fluorescent turn-on mechanism is accomplished by suppression of photoinduced electron transfer (PET) from the methyl phenyl sulfide group to BODIPY. The fluorescence intensity of the reaction between HOCl and HCS shows a good linearity in the HOCl concentration range 1-10 mu M. The detection limit is 23.7 nM (S/N = 3). In addition, confocal fluorescence microscopy imaging using RAW264.7 macrophages demonstrates that the HCS probe could be an efficient fluorescent detector for HOCl in living cells. (C) 2013 Published by Elsevier B.V.
Energy-conserving data gathering by mobile mules in a spatially separated wireless sensor network
(2013-10-25)
Wu, Fang-Jing
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
This paper considers a spatially separated wireless sensor network, which consists of a number of isolated subnetworks that could be far away from each other in distance. We address the issue of using mobile mules to collect data from these sensor nodes. In such an environment, both data-collection latency and network lifetime are critical issues. We model this problem as a bi-objective problem, called energy-constrained mule traveling salesman problem (EM-TSP), which aims at minimizing the traversal paths of mobile mules such that at least one node in each subnetwork is visited by a mule and the maximum energy consumption among all sensor nodes does not exceed a pre-defined threshold. Interestingly, the traversal problem turns out to be a generalization of the classical traveling salesman problem (TSP), an NP-complete problem. With some geometrical properties of the network, we propose some efficient heuristics for EM-TSP. We then extend our heuristics to multiple mobile mules. Extensive simulation results have been conducted, which show that our proposed solutions usually give much better solutions than most TSP-like approximations. Copyright (c) 2011 John Wiley & Sons, Ltd.
Strain modulated optical properties in BiFeO3 thin films
(2013-10-28)
Liu, H. L.
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Lin, M. K.
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Cai, Y. R.
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Tung, C. K.
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Chu, Y. H.
Spectroscopic ellipsometry was used to investigate the strain-dependent optical properties of BiFeO3 thin films. At room temperature, the compressively strained BiFeO3/LaAlO3 thin films show the largest band gap of about 3.12 eV. It redshifts to 2.75 eV for the tensile strained BiFeO3/NdScO3 thin films. With increasing temperature, observable anomalies in the band gap for all strained thin films near 640K indicate that antiferromagnetic transition temperature is independent of strain and close to its bulk value, which are in good agreement with the first-principles calculations. These results further suggest a complex nature of charge-spin coupling in multiferroic BiFeO3 thin films. (c) 2013 AIP Publishing LLC.
群己權界《論自由》：彌爾自由主義的啟示
(2013-10-28)
王冠生
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開放教育推動中心
;
Open Education Office
課程首頁本課程是由交通大學新文藝復興閱讀計畫提供。 96 年 8 月當各大學紛紛摩拳擦掌準備迎接新生的同時，交通大學校長吳重雨則因為一則來自於七月份泰晤士報，有關於英國首相布朗公布其夏日讀書清單的新聞中，看到了他對知識的尊重。在這同時，吳重雨校長也思考著，要如何為學生準備追求知識的環境和激發他們對知識的尊重與喜愛。台積電張忠謀董事長曾陳述他 18 歲進入哈佛那一年，博覽文史哲理工經典群籍，至此奠定了他求知的基礎，並借海明威名言，將其改為「哈佛這一年為人生可帶走的盛宴。」吳重雨校長以張董事長的學習為借鏡，認為學生固然能藉由自我閱讀的方式學習到豐沛的知識，但透過名人、大師親臨現場地介紹經典書籍，更能加深學子們對於書籍的認識與興趣，這也是「新文藝復興閱讀計劃」 ( 以下簡稱 : 「經典名著選讀」 ) 活動展開籌劃的緣由。於是，吳重雨校長便積極敦請「交大通識教育委員會」，接手籌備本計劃的相關活動，而該中心也成為實際施行本計畫的策動、開課以及認證單位。至此，期許交大學子藉由閱讀、聽講來提昇人文素養、開拓視野的「新文藝復興閱讀計劃」，就此展開。
Suppressed piezoelectric polarization in single InGaN/GaN heterostructure nanowires
(2013-10-28)
Tsai, Wen-Che
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Chen, Yen-Ting
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Lin, Chia-Hsien
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Hsu, Wei-Ting
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Hsu, Yung-Sheng
The optical properties of single InGaN/GaN heterostructure nanowires (NWs) with a mean diameter down to 18 nm are investigated. Sharp emission lines originating from the recombination of localized excitons in the InGaN disk layer can be resolved. Excitation-dependent energy shifts, together with spectral diffusions of these emission lines, indicate the presence of a weak quantum confined Stark effect (QCSE) caused by nearby charge fluctuations, rather than the screening of piezoelectric polarizations at the InGaN/GaN interface. The absence of a piezoelectric polarization field is further confirmed by time-resolved photoluminescence measurements. Numerical simulations reveal that the elastic strain relaxation via the NW geometry is marginal and occurs only near the NW sidewalls. Carrier localization preferentially near the periphery of the InGaN disk and alloy intermixing are suggested as possible reasons for the absence of a polarization-induced QCSE in thin InGaN/GaN heterostructure NWs.
System and method for processing a frequency division multiplexing signal
(2013-10-29)
Wang Hai-wei
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Lin David W.
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Sang Tzu-Hsien
A method for processing a frequency division multiplexing signal transmitted in a channel is provided. The method includes the steps of a) receiving the frequency division multiplexing signal having a residual intercarrier interference (ICI) and a channel noise and transmitted by plural subcarriers; b) performing a cyclic prefix removal and a discrete Fourier transform for the frequency division multiplexing signal to obtain a frequency-domain signal; c) analyzing the frequency-domain signal to obtain a plurality of correlation values for the residual ICI and the channel noise; and d) performing a communication signal processing for the frequency division multiplexing signal based on at least one of the plural correlation values.
Glove puppet manipulating system
(2013-10-29)
Hu Jwu-Sheng
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Wang Jyun-Ji
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Sun Guan-Qun
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Tang Chi-Him
A glove puppet manipulating system comprises a control module for generating control signals base on movements of human hand and a robot electrically connecting the control module installed inside a glove puppet. The robot has a body manipulating apparatus disposed on a foundation to manipulate the body of the glove puppet to rotate, a pair of hand manipulating apparatuses disposed on the body manipulating apparatus to manipulate the hands of the glove puppet to swivel, and a head manipulating apparatus interposed between the hand manipulating apparatuses on the body manipulating apparatus to manipulate the head of the glove puppet to nod.
Measurement of Interlayer Screening Length of Layered Graphene by Plasmonic Nanostructure Resonances
(2013-10-31)
Chen, Hsiang-An
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Hsin, Cheng-Lun
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Huang, Yu-Ting
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Tang, Ming Lee
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Dhuey, Scott
The variation in localized surface plasmon resonances of single Au nanodisks (diameter 100 nm and height 25 nm) on 0-13 graphene layers is investigated using dark-field scattering spectroscopy to obtain the graphene electric field screening length. For nanodisks (NDs) with and without underlying graphene layers on a SiO2 (300 nm)/Si substrate, the plasmon resonance red shifts from 604 to 620 nm with increasing graphene layers. The spectra of the plasmonic nanostructures obey an exponential saturation function versus increasing number of layers of graphene from 0 to 13. As a conducting film, the graphene layers screen the electric field generated by the plasmonic resonance of the Au NDs in the vicinity of the interface, and the red shifts of the resonance wavelength are explained in the framework of the electromagnetic field coupling between in-plane antiparallel image dipoles in the graphene layers and the ND dipole. A screening length of 1.2 +/- 0.2 nm, equivalent to 3-4 graphene layers, is experimentally obtained, in good agreement with the measurement by field-effect transistors and theoretical calculation in doped graphene. The resonance shift of plasmonic nanostructures on a layered graphene system provides an alternative and convenient method for screening length measurement of graphene films.
Device for Measuring and Analyzing Electromyography signals
(2013-10-31)
CHOU Willy
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Lin Bor-Shyh
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Ou Chien-Zhi
A device is for measuring and analyzing electromyography signals obtained from a target body part that is divided into an unhealthy-side muscle group and a healthy-side muscle group, and includes an unhealthy-side measuring electrode unit to be disposed on the unhealthy-side muscle group for measuring an electromyography signal therefrom so as to generate unhealthy-side measured data, a healthy-side measuring electrode unit to be disposed on the healthy-side muscle group for measuring an electromyography signal therefrom so as to generate healthy-side measured data, and a control unit determining a correlation between the unhealthy-side measured data and the healthy-side measured data.
Doping evolution of Zhang-Rice singlet spectral weight: A comprehensive examination by x-ray absorption spectroscopy
(2013-10-31)
Chen, Y. -J.
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Jiang, M. G.
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Luo, C. W.
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Lin, J. -Y.
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Wu, K. H.
The total spectral weight S of the emergent low-energy quasiparticles in high-temperature superconductors (HTSCs) is explored by x-ray absorption spectroscopy. In order to examine the applicability of the Hubbard model, regimes that cover from zero doping to overdoping are investigated. In contrast to results of mean-field theory, we found that S deviates from linear dependence on the doping level p. The slope of S versus p changes continuously throughout the whole doping range with no sign of saturation up to p = 0.23. Therefore, the picture of the Zhang-Rice singlet remains intact within the most prominent doping regimes of HTSCs.
範式、概念與方法：中國大陸客家研究的學術歷程與理論反思
(2013-11)
黃志繁
;
Zhifan Huang
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College of Hakka Studies
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International Center for Hakka Studies
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客家文化學院
中國大陸客家研究經歷了三個階段：「前羅香林時代」、「羅香林時代」、「族群理論時代」。研究範式則經歷了從「文化——民系」範式向「族群——認同」範式的轉換，在這一轉換過程中，「族群」概念逐漸取代了「民系」概念。「方言群體」或許是個比較合適指稱客家的概念，但仍應從整體史的角度觀察客家地區的歷史。將來中國大陸的客家研究，應盡力融入歷史學、社會學、人類學等學科中，並為這些學科提供學術資源才能獲得更大發展；研究方法和領域上應盡量採用歷史人類學的方法拓展客家區域社會經濟史。關於客家源流問題已經耗費客家學者太多精力，學界關注的中心問題應以「客家形成」代替「客家特質」，致力於更加清晰地展示客家區域社會變遷過程。
王力堅：《新加坡客家會館與文化研究》
(2013-11)
利亮時
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Leong-sze Lee
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College of Hakka Studies
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International Center for Hakka Studies
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客家文化學院
這本有關客家會館的著作，主要分成兩個部分，第一輯為客家會館與文化探討，而第二輯則是客家會館與客家研究訪談。本書主要是新加坡茶陽(大埔) 會館與新加坡國立大學中文系共同合作的客家研究系列叢書的第一本。
An optimal design of thermal-actuated and piezoresistive-sensed CMOS-MEMS resonant sensor
(2013-11-01)
Wang, Chun-Chieh
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Tsai, Chun-Yin
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Chen, Tsung-Lin
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Liao, Sin-Hao
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機械工程學系
This paper proposes an optimal design of the thermal-actuated, piezoresistive-sensed resonator fabricated by a foundry-provided CMOS-MEMS process. The optimal design is achieved both by quantitatively comparing the mechanical properties of different composite films as well as by deriving an analytical model for determining the device dimensions. The analytical model includes a stress model of an asymmetric mechanical structure and a piezoresistivity model of the heavily doped, n-type polysilicon film. The analytical model predicts that the optimal length of the displacement sensor is 200 mu m when the thermal actuator is 200 mu m in length and the absorption plate is 100 mu m in length. Additionally, the model predicts the resistivity of the polysilicon film of (6.8 +/- 2.2) m Omega cm and the gauge factor of (6.8 +/- 2.9) when the grain size is (250 +/- 100) nm. Experimental results agree well with simulation results. Experimental data show that the resonant frequency of the device is 80.06 kHz and shifts to 79.8 kHz when a brick of Pt mass is deposited on the resonator. The mass of the Pt estimated from the frequency shift is 4.5419 x 10(-12) kg, while estimated from the measured dimension is 4.4204 x 10(-12) kg. Sensitivity of the resonant sensor is calculated to be 1.8 x 10(2) Hz ng(-1). Experimental results further show that the polysilicon film used in the experiments has a grain size of (241 +/- 105) nm, an average gauge factor of 5.56 and average resistivity of 5.5 m Omega cm.
Instruction-Cycle-Based Dynamic Voltage Scaling Power Management for Low-Power Digital Signal Processor With 53% Power Savings
(2013-11-01)
Peng, Shen-Yu
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Huang, Tzu-Chi
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Lee, Yu-Huei
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Chiu, Chao-Chang
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Chen, Ke-Horng
This paper presents and analyzes a fully digital instruction-cycle-based dynamic voltage scaling (iDVS) power management strategy for low-power processor designs. The proposed iDVS technique is fully compatible with conventional DVS scheduler algorithms. An additional computer aided design-based design flow was embedded in a standard cell library to implement the iDVS-based processor in highly integrated system-on-a-chip applications. The lattice asynchronous self-timed control digital low-dropout regulator with swift response and low quiescent current was also utilized to improve iDVS voltage transition response. Results show that the iDVS-based processor with the proposed adaptive instruction cycle control scheme can efficiently perform millions of instructions per second during iDVS transition. The iDVS-based digital signal processor chip was implemented in a HH-NEC 0.18-mu m standard complementary metal-oxide semiconductor. Measurement results show that the voltage tracking speed with 11.6 V/mu s saved 53% power.
Forwarding Methods in Data Dissemination and Routing Protocols for Vehicular Ad Hoc Networks
(2013-11-01)
Daraghmi, Yousef-Awwad
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Yi, Chih-Wei
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Stojmenovic, Ivan
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資訊工程學系
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Department of Computer Science
Intermittent connectivity, abrupt changes in network topology and low reception rate are the most important properties that distinguish VANET (vehicular ad hoc networks) from other types of ad hoc networks. To optimize reliability and time criticality metrics in data communication protocols for VANET, novel ideas are needed. In this article, we present a tutorial on methods (at the network layer), encountered in recent literature, for small and large scale routing protocols, and geocasting (broadcasting, data dissemination, and warning delivery) protocols.
The formation of quasi-nondiffracting focused beams with second-harmonic generation of flower Laguerre-Gaussian modes
(2013-11-01)
Lin, Y. C.
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Huang, K. F.
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Chen, Y. F.
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電子物理學系
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Department of Electrophysics
We theoretically demonstrate that the second-harmonic generation of a flower Laguerre-Gaussian mode can be exploited to form a quasi-nondiffracting focused beam. It is verified that the product of donut Laguerre-Gaussian modes with opposite topological charges leads to the formation of the quasi-nondiffracting focused beam. The divergence of the quasi-nondiffracting focused beam is numerically confirmed to be root 2l + 1 times less than that of the Gaussian TEM00 mode with the same beam waist parameter, where l is the azimuthal index of the flower Laguerre-Gaussian mode. In an experiment, we employ a diode-pumped solid-state laser resonator with intracavity second-harmonic generation to realize the formation of the quasi-nondiffracting focused beams.