Browsing by Issue Date, starting with "2019-01-10"

Now showing 1 - 20 of 8308

SDN-based dynamic multipath forwarding for inter-data center networking
(2019-01-10)
Wang, Yao-Chun
;
Lin, Ying-Dar
;
Chang, Guey-Yun
;
資訊工程學系
;
Department of Computer Science
Equal-cost multipath (ECMP)-based traffic engineering (TE) methods are commonly used in intra-data center (DC) networks to improve the transmission performance for east-west traffic (ie, traffic from server to server within a DC). However, applying ECMP on inter-DC wide area network (WAN) offers limited performance enhancement as a result of irregular network topology. Since TE can be intelligently and efficiently realized with software-defined networking (SDN), SDN-based multipath becomes a popular option. However, SDN suffers from scalability issue caused by limited ternary content-addressable memory (TCAM) size. In this paper, we propose an SDN-based TE method called dynamic flow-entry-saving multipath (DFSM) for inter-DC traffic forwarding. DFSM adopts source-destination-based multipath forwarding and latency-aware traffic splitting to reduce the consumption of flow entries and achieve load balancing. The evaluation results indicate that DFSM saves 15% to 30% of system flow entries in practical topologies and reduces the standard deviation of path latencies from 10% to 7% than do label-switched tunneling, and also reduces average latency by 10% to 48% by consuming 6% to 20% more flow entries than do ECMP in less-interconnected topologies. Note that the performance gain may not always be proportional to flow entry investment, with the interconnectivity between nodes being an important factor. The evaluation also indicates that per-flow provision consumes several times the flow entries consumed by DFSM but reduces latency by 10% at most. Besides, DFSM reduces the standard deviation of path latencies from 14% to 7% than do even traffic splitting.
A light-weight bit commitment protocol based on unpredictable channel noise
(2019-01-10)
Guan, Albert
;
Tzeng, Wen-Guey
;
資訊工程學系
;
Department of Computer Science
Bit commitment is an important tool in the design of many secure cryptographic protocols, such as coin flipping, zero-knowledge proof, and secure computation. In this paper, we present a computationally light-weight bit commitment protocol over a noisy channel. For the security of the proposed protocol, we show that the receiver has almost no information about the committer's secret due to unpredictability of the noises in the communication channel. Hence, the security of our bit commitment protocol does not depend on hard problems; it is information-theoretically secure. Furthermore, the protocol needs only exclusive-or operations. Thus, it is computationally light-weight, and it can be used in the devices whose computing resources are limited. (C) 2018 Elsevier B.V. All rights reserved.
The evaluation of a better intubation strategy when only the epiglottis is visible: a randomized, cross-over mannequin study
(2019-01-10)
Hung, Tzu-Yao
;
Lin, Li-Wei
;
Yeh, Yu-Hang
;
Su, Yung-Cheng
;
Lin, Chieh-Hung
BackgroundThe Cormack-Lehane (C-L) grade III airway is considered to be a challenging airway to intubate and is associated with a poor intubation success rate. The purpose of this study was to investigate whether the holding position, shapes, bend angles of the endotracheal tube (ET) and the stylet-assisted lifting of the epiglottis could improve the success rate of intubation.MethodsThirty-two participants, 26 physicians, 2 residents, and 4 nurse practitioners, with 12.095.38years of work experience in the emergency department and more than 150 annual intubation events, were enrolled in this randomized, cross-over mannequin study. We investigated the effects of straight-to-cuff ET shapes with 35 degrees and 50 degrees bend angles, banana-shaped ET with longitudinal distances of 28cm and 26cm, two methods of holding the ET (either on the top or in the middle), and lifting or not the epiglottis, on the intubation duration, its success rate, and its subjective difficulty. The aim of the study is to provide optimized intubation strategies for difficult airway with C-L IIb or III grades, when the inlet of the trachea cannot be visualized.ResultsThe two groups that lifted the epiglottis using the stylets, in bend angles of 35 degrees and 50 degrees, had the shortest duration of intubation (23.7514.24s and 20.72 +/- 6.90s, hazard ratios 1.54 and 1.85 with 95% confidence intervals [95% CI] of 1.01-2.34 and 1.23-2.78, respectively) and a 100% success rate in intubations. In the survival analysis, lifting of the epiglottis was the only significant factor (p<0.0001, 95% CI 1.34-2.11) associated with the success rate of intubation.ConclusionsThe use of the epiglottic lift as an adjunctive technique can facilitate the intubation and improve its success rate without increasing procedure difficulty, in C-L III airway, when only the epiglottis is seen.Trial registration ClinicalTrials Registry (https://clincaltrials.gov, identifier NCT03366311).
Mimicking surface polaritons for unpolarized light with high-permittivity materials
(2019-01-10)
Papadakis, Georgia T.
;
Davoyan, Artur
;
Yeh, Pochi
;
Atwater, Harry A.
;
光電工程學系
Tailoring near-field optical phenomena often requires excitation of surface plasmon polaritons (SPPs) or surface phonon polaritons (SPhPs), surface waves at the interface between media with electric permittivities of opposite sign. Despite their unprecedented field confinement, surface polaritons are limited by polarization: only transverse magnetic fields enable their excitation, leaving transverse electric fields unexploited. By contrast, guided modes in positive permittivity materials occur for both linear polarizations, however, they typically cannot compete with SPPs and SPhPs in terms of confinement. Here we show that omnipolarization guided modes in materials with high-permittivity resonances can reach confinement factors similar to SPPs and SPhPs, while surpassing them in terms of propagation distance. We explore the cases of silicon carbide and transition-metal dichalcogenides near their permittivity resonances, and compare with SPhPs in silicon carbide and SPPs in silver, at infrared and visible frequencies, respectively.
Renal chymase-dependent pathway for angiotensin II formation mediated acute kidney injury in a mouse model of aristolochic acid I-induced acute nephropathy
(2019-01-11)
Hsieh, Wen-Yeh
;
Chang, Teng-Hsiang
;
Chang, Hui-Fang
;
Chuang, Wan-Hsuan
;
Lu, Li-Che
Angiotensin-converting enzyme (ACE) is the primary enzyme that converts angiotensin I (Ang I) to angiotensin II (Ang II) in the renin-angiotensin system (RAS). However, chymase hydrates Ang I to Ang II independently of ACE in some kidney diseases, and it may play an important role. The present study investigated whether chymase played a crucial role in aristolochic acid I (AAI)-induced nephropathy. C57BL/6 mice were treated with AAI via intraperitoneal injection for an accumulated AAI dosage of 45 mg/kg body weight (BW) (15 mg/kg BW per day for 3 days). The animals were sacrificed after acute kidney injury development, and blood, urine and kidneys were harvested for biochemical and molecular assays. Mice exhibited increased serum creatinine, BUN and urinary protein after the AAI challenge. Significant infiltrating inflammatory cells and tubular atrophy were observed in the kidneys, and high immunocytokine levels were detected. Renal RAS-related enzyme activities were measured, and a significantly increased chymase activity and slightly decreased ACE activity were observed in the AAI-treated mice. The renal Ang II level reflected the altered profile of RAS enzymes and was significantly increased in AAI-treated mice. Treatment of AAI-induced nephropathic mice with an ACE inhibitor (ACEI) or chymase inhibitor (CI; chymostatin) reduced renal Ang II levels. The combination of ACEI and CI (ACEI+CI) treatment significantly reversed the AAI-induced changes of Ang II levels and kidney inflammation and injuries. AAI treatment significantly increased renal p-MEK without increasing p-STAT3 and p-Smad3 levels, and p-MEK/p-ERK1/2 signalling pathway was significantly activated. CI and ACEI+CI treatments reduced this AAI-activated signaling pathway. AAI-induced nephropathy progression was significantly mitigated with CI and ACEI+CI treatment. This study elucidates the role of RAS in the pathogenesis of AAI-induced nephropathy.
Regio- and stereo-selective [4+4] photodimerization of angular-shaped dialkyltetracenedithiophene
(2019-01-11)
Hsu, Tze-Gang
;
Chou, Hsiao-Chieh
;
Liang, Ming-Ju
;
Lai, Yu-Ying
;
Cheng, Yen-Ju
Angular-shaped dialkyltetracenedithiophenes (aTDTs) undergo [4+4] photodimerization in solution to form a butterfly-shaped skeleton. This reaction proceeds in a regio- and stereo-selective manner, forming only a single planosymmetric syn-[2,2]-daTDT out of six possible products. The photocycloaddition of aTDTs can take place topochemically in the thin-film state while maintaining regio- and stereo-selectivity. Stronger aliphatic dispersion forces and - interactions play important roles in forming the eclipsed dimeric complex that leads to the syn-[2,2]-daTDT isomer.
A numerical study on reaction-induced radial fingering instability
(2019-01-11)
Sharma, Vandita
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Pramanik, Satyajit
;
Chen, Ching-Yao
;
Mishra, Manoranjan
;
機械工程學系
The dynamics of A + B -> C fronts is analysed numerically in a radial geometry. We are interested to understand miscible fingering instabilities when the simple chemical reaction changes the viscosity of the fluid locally and a non-monotonic viscosity profile with a global maximum or minimum is formed. We consider viscosity-matched reactants A and B generating a product C having different viscosity than the reactants. Depending on the effect of C on the viscosity relative to the reactants, different viscous fingering (VF) patterns are captured which are in good qualitative agreement with the existing radial experiments. We have found that, for a given chemical reaction rate, an unfavourable viscosity contrast is not always sufficient to trigger the instability. For every fixed Peclet number (Pe), these effects of chemical reaction on VF are summarized in the Damkohler number (Da) - the log-mobility ratio (R-c) parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing Pe, we determine Da-dependent critical log-mobility ratios R-c(+) and R-c(-) such that no VF is observable whenever R-c(-) <= R-c <= R-c(+). The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.
Finite-size scaling for four-dimensional Higgs-Yukawa model near the Gaussian fixed point
(2019-01-14)
Chu, David Y. -J.
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Jansen, Karl
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Knippschild, Bastian
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Lin, C. -J. David
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電子物理學系
We analyse finite-size scaling behaviour of a four-dimensional Higgs-Yukawa model near the Gaussian infrared fixed point. Through improving the mean-field scaling laws by solving one-loop renormalisation group equations, the triviality property of this model can be manifested in the volume-dependence of moments of the scalar-field zero mode. The scaling formulae for the moments are derived in this work with the inclusion of the leading-logarithmic corrections. To test these formulae, we confront them with data from lattice simulations in a simpler model, namely the O(4) pure scalar theory, and find numerical evidence of good agreement. Our results of the finite-size scaling can in principle be employed to establish triviality of Higgs-Yukawa models, or to search for alternative scenarios in studying their fixed-point structure, if sufficiently large lattices can be reached.
最小曲面的黃金年代：柯丁/米尼庫齊理論
(國立交通大學丘成桐中心, 2019-01-15)
裴瑞茲
;
王夏聲
;
Joaquín Pérez
作者裴瑞茲是西班牙格蘭納達大學的數學與拓樸學教授與數學研究所（IEMath-GR）的主任。該研究所是屬於西班牙國家研究委員會所設的四個數學研究所其中之一。他也是西班牙皇家數學學會的國際關係委員會的一員。歷史上許多偉大的數學家都曾面對過最小曲面問題的挑戰，其中有一些數學家在相對確定的時期內獲得了驚人的進展，而促成了最小曲面的黃金年代。
大型線性方程組解法
(國立交通大學丘成桐中心, 2019-01-15)
許進超
．如何找線性代數方程組的解？這在數學與應用中是一個非常基本的問題，作者在本文討論求解的數值方法。．從最古老的高斯消去法到現代的多層網格法，作者在文中演示如何以數學技術研發大規模線性方程組的有效方法。．作者也有對於電腦硬體的開發與數學演算法的開發之間作出比較與探討。
解決物理難題的數學大師：我熟識的丘成桐先生
(國立交通大學丘成桐中心, 2019-01-15)
薛其坤
著者簡介:薛其坤是國際著名的實驗物理學家，現在是北京清華大學副校長，物理學教授，中國科學院院士。他的主要研究方向為量子物理。2013年他所帶領的團隊與合作者首次從實驗上發現量子反常霍爾效應，被2016年諾貝爾物理獎評獎委員會列入該領域過去三十年最重要的實驗發現。丘成桐先生是馳名中外的數學家，哈佛大學終身教授，國際數學最高獎「費爾茲獎」得主。我們都知道丘先生少年成名，標準的「學霸」一枚。22歲博士畢業，25 歲任副教授，27 歲攻克世界數學難題「卡拉比猜想」，34 歲獲得費爾茲獎。他幾乎拿遍了世界級的數學大獎，並已成為受人尊重的華人數學家領袖。
Growth of foreign-catalyst-free vertical InAs/InSb heterostructure nanowires on Si (111) substrate by MOCVD
(2019-01-15)
Anandan, Deepak
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Kakkerla, Ramesh Kumar
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Yu, Hung Wei
;
Ko, Hua Lun
;
Nagarajan, Venkatesan
In this study, growth of Au-free InAs/InSb vertical heterostructure (HS) nanowires (NWs) on highly lattice mismatched Si (1 1 1) substrate by metal organic chemical vapor deposition (MOCVD) is demonstrated. Careful selections of InSb growth parameters lead to In-rich growth regime such that direct impingement of growth precursors on top of grown InAs NW (self-assembled) stems result in axial InSb HSs nucleation on InAs stems. The observed indium (In) droplet on InSb HS NW tip shows that InSb HS growth followed a self-catalyzed growth mechanism. InSb HS axial growth rate and morphology are controlled by growth temperature and growth time. A small change in the growth parameters significantly affects In particle accumulation, particle size and its chemical composition, and thus affects the InSb nucleation on the stem. Especially, it is found that (i) growth time of less 10 min yields vertical InSb HS NW on the top of the InAs stem, (ii) as the growth time increases above 10 min, the growth turned to be InSb wrapped InAs/InSb core-shell HS due to coaxial lateral growth. High resolution transmission electron microscopy (HRTEM) study reveals that all the InSb HSs exhibit pure zinc-blende (ZB) crystal structure. The results presented here provide significant guidelines for external catalyst-free InAs/InSb HS NW growth using MOCVD on silicon (Si) substrate for various optoelectronics and electronics applications.
Relaxation high-temperature ratchets
(2019-01-15)
Shapochkina, I. V.
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Rozenbaum, V. M.
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Sheu, S. -Y.
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Yang, D. -Y.
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Lin, S. H.
We consider the overdamped motion of a Brownian particle in an asymmetric spatially periodic potential which fluctuates periodically in time, under assumption of finite duration of the relaxation response of the system on deterministic dichotomous fluctuations. It is assumed that the period of these fluctuations is much larger than the characteristic diffusion time and the potential barrier height is small as compared to the thermal energy (an adiabatic high-temperature flashing ratchet). We derive an analytical expression for the average particle velocity, which is concretized for a saw-tooth potential profile. It is revealed the different, linear and quadratic, asymptotic behavior of the average velocity as a function of the relaxation time for extremely and not extremely asymmetric potential profiles, respectively. The result is interpreted in terms of the self-similar representation. (C) 2018 Elsevier B.V. All rights reserved.
將物理應用於數學
(國立交通大學丘成桐中心, 2019-01-15)
時枝正
;
江孟蓉
;
Tadashi Tokieda
作者時枝正在日本長大，最初是一位畫家，後來在法國成為古典語文學者。然後轉行從事數學研究，再換到物理領域。他現在是史丹福大學的數學教授，之前曾以英國劍橋大學為根據地工作多年。他積極參與在開發中國家的教育推廣，尤其是透過非洲數學科學研究院（African Institute for Mathematical Sciences，AIMS）。有時候數學定理是這樣湧現的：設定一個物理情境，從物理學的經驗來看會發生什麼現象，把它翻成數學語言，就成為一個定理。本文展示四個初階的例子：三角形的餘弦定律、正弦定律、柯西 / 史瓦茲不等式、算數幾何平均不等式。
無用研究的有效性：大栗博司Kavli IPMU 主任就職演說
(國立交通大學丘成桐中心, 2019-01-15)
大栗博司
;
陳明鈺
;
Hirosi Ooguri
作者大栗博司是加州理工大學的理論物理與數學的卡弗里講座教授與柏克（Walter Burke）理論物理研究所所長，卡弗里數物連攜宇宙研究機構（Kavli Institute for the Physics and Mathematics of the Universe，Kavli IPMU）與東京大學國際高等研究所（The University of Tokyo Institute for Advanced Study，UTIAS）主任。他的研究領域是基本粒子物理，弦論和相關的數學理論。本文出自大栗博司的2018 年 10 月 8 日Kavli IPMU 主任就職演說。
編輯曲線
(國立交通大學丘成桐中心, 2019-01-15)
編輯室
本期內容:畢氏法則
只有詠唱才能學會詠唱（下）：悼威廉‧瑟斯頓(1946～2012)
(國立交通大學丘成桐中心, 2019-01-15)
噶拜
;
科寇夫
;
翁秉仁
;
David Gabai
;
Steve Kerckhoff
作者噶拜現為普林斯頓大學教授。科寇夫現為史丹福大學教授。本文出自“William P. Thurston 1946-2012” Notices of the AMS (63) 2016 No. 1。這裡是下篇（上篇請見數理人文 14 期）。
Electro-autotrophs induced the growth of exoelectrogens on the anode in a microbial fuel cell
(2019-01-15)
Chen, Kuo-Ti
;
Bai, Min-Der
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Wu, Shao-I
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Chen, Chang-Chieh
;
Lu, Wen-Jang
In microbial fuel cells (MFCs), exoelectrogens act as a catalyst and produce electricity directly. Exoelectrogens such as Geobacter in the heterotrophic condition acts as electron donors but when they transferred to the autotrophic condition, they act as electron acceptors and undergo continuous growth. However, most of the nonelectrochemical bacteria will collapse and disperse in the liquid phase with environmental change. In this study, we used electro-autotroph and acetate enrichment alternately rather than only an acetate-fed control system in the batch operation. After the five-batch operation, the microorganism diversity shifted from complex to simple, and Geobacter was the most abundant microorganism in the experimental system. The coulombic efficiency (CE) and the highest current density were 20%--45%, and 657 mA/m(2), respectively, for the experimental group and 8%-20%, and 511 mA/m(2), respectively, for the control group. The monosodium glutamate wastewater was treated in this study. The control group was acclimated in a shorter time, but the experimental group had higher current density and CE. The results indicate that the electro-autotroph process reduced the number of non-bioelectrochemical bacteria but induced the growth of exoelectrogens on the electrode, resulting in the MFCs achieving a higher efficiency.
iSIRA: Integrated shift-invert residual Arnoldi method for graph Laplacian matrices from big data
(2019-01-15)
Huang, Wei-Qiang
;
Lin, Wen-Wei
;
Lu, Henry Horng-Shing
;
Yau, Shing-Tung
;
交大名義發表
The eigenvalue problem of a graph Laplacian matrix L arising from a simple, connected and undirected graph has been given more attention due to its extensive applications, such as spectral clustering, community detection, complex network, image processing and so on. The associated matrix L is symmetric, positive semi-definite, and is usually large and sparse. It is often of interest for finding some smallest positive eigenvalues and corresponding eigenvectors. However, the singularity of L makes the classical eigensolvers inefficient since we need to factorize L for the purpose of solving large and sparse linear systems exactly. The next difficulty is that it is usually prohibitive to factorize L generated by real network problems from big data such as social media transactional databases, and sensor systems because there is in general not only local connections. In this paper, we propose a trimming to cure the singularity of L according to its special property: zero row/column sum. This remedy technique leads us to solve a positive definite linear system reduced in one dimension and then recover the result to get a suitable solution of the original system involved in an eigensolver. Besides, we apply a deflating approach to exclude the influence of converged eigenvalues. We show how to apply the idea of trimming to the graph Laplacian eigenvalue problem together with a deflated term and a target shift. Accordingly, based on the inexact residual Arnoldi (Lee, 2007; Lee and Stewart, 2007) method, we propose an integrated eigensolver for this kind of L combining with the implicit remedy of the singularity, an effective deflation for convergent eigenvalues and the shift-invert enhancement. Numerical experiments reveal that the integrated eigensolver outperforms the classical Arnoldi/Lanczos method for computing some smallest positive eigeninformation especially when the LU factorization is not available. (C) 2018 Elsevier B.V. All rights reserved.
畢氏法則：第一個數學定理？！
(國立交通大學丘成桐中心, 2019-01-15)
大衛 ‧ 曼弗德
;
趙學信
;
David Mumford
作者曼弗德現為哈佛大學與布朗大學退休榮譽教授，研究領域是代數幾何與圖形視覺與模式理論。曾獲頒費爾茲獎（1974），麥克阿瑟獎（1987）與沃爾夫獎（2008）