Browsing by Issue Date, starting with "2017-01-15"

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專題-秩序與複雜的華爾滋（上）簡單通往複雜之路
(國立交通大學丘成桐中心, 2017-01-15)
班榮超　
科學家對成長函數超過一甲子的狂熱
在里約海灘發現馬蹄鐵
(國立交通大學丘成桐中心, 2017-01-15)
周樹靜　
電影《侏羅紀公園》中，有一位數學家在討論混沌（chaos）。葛雷易克（James Gleick）的《混沌》長期占據暢銷書排行榜，史托帕德（Tom Stoppard）知名劇作《艾凱狄雅》（Arcadia）中的角色高談混沌的意義。到底，大家在興奮個什麼勁？
專題-秩序與複雜的華爾滋（上）心臟與大腦中的秩序與混沌
(國立交通大學丘成桐中心, 2017-01-15)
陳志強
;
楊穎任
冪次律和自相似性一例
四位大物理學家眼中高能物理的未來
(國立交通大學丘成桐中心, 2017-01-15)
何紅建　　
霍金、格拉肖、溫伯格、韋頓談中國的巨型對撞機計畫
Generation of terahertz optical beating from a simultaneously self-mode-locked Nd: YAG laser at 1064 and 1123 nm
(2017-01-15)
Sung, C. L.
;
Lee, C. Y.
;
Chang, C. C.
;
Liang, H. C.
;
Chen, Y. F.
The reflectivity of the output coupler is designed to achieve the synchronously self-mode-locked operation at 1064 and 1123 nm in a diode-end-pumped Nd:YAG laser. Numerical analyses are performed to confirm that the designed output coupler can lead the emission lines to be predominant at 1064 and 1123 nm. Moreover, the crossover of the threshold pump powers for the 1064 and 1123 nm emission lines can be exploited to obtain the single central wavelength of 1064 nm or the single central wavelength of 1123 nm or, simultaneously, dual-central-wavelength self-mode-locked operation by finely adjusting the cavity alignment. For the dual-central-wavelength mode-locked emissions, the pulse repetition rate and the pulse duration are 4.5 GHz and 50.8 ps, respectively. The maximum output power can be up to 2.47 W at a pump power of 7.5 W. The synchronization of the 1064 and 1123 nm mode-locked pulses generates the optical beating pulse trains with repetition rates up to 14.7 THz. (C) 2017 Optical Society of America
V-band gapless OFDM RoF system with power detector down-conversion and novel Volterra nonlinear filtering
(2017-01-15)
Lin, Chun-Ting
;
Chiang, Shou-Chih
;
Li, Che-Hao
;
Huang, Hou-Tzu
;
Lin, Chi-Hsiang
This Letter presents a V-band gapless orthogonal frequency division multiplexing (OFDM) RoF system at 60 GHz employing a power detector to support vector signal down-conversion. Additional RF tone is generated and transmitted from a central station to replace the local oscillator at a wireless receiver for power detector down-conversion. To enhance the spectrum efficiency, the gap between the OFDM signal and the RF tone is not needed. However, the down-converted signal will suffer signal-to-signal interference (SSBI). In this Letter, we propose and successfully employ a novel Volterra nonlinear compensation to mitigate SSBI, resulting in a 22% data rate improvement with a bit-loading algorithm. (C) 2017 Optical Society of America
Group key management with efficient rekey mechanism: A Semi-Stateful approach for out-of-Synchronized members
(2017-01-15)
Chen, Yi-Ruei
;
Tzeng, Wen-Guey
;
資訊工程學系
;
Department of Computer Science
This paper addresses the problem of managing a cryptographic group key among a large and highly dynamic group of members, who may miss group key update (rekey) messages frequently. We propose two provably-secure and practical schemes: KeyDer-GKM and ReEnc-GKM. The rekey process in these schemes has an O(logN) rekey message and O(logN) computation and storage cost for a member, where N is the number of group members. Moreover, our schemes have the following distinct features. (1) Each member is given only one private key and O(logN) public information. The private key remains unchanged during the membership period. For the public information, a member can hold them locally and update accordingly from each rekey message, or get them from a public bulletin if needed. (2) The size of published information is O(N) no matter how many rekey processes occur. The computation cost for a member, who has missed some rekey messages, to compute the up-to-date group key is always O(logN) no matter how many rekey messages have been missed. Our KeyDer-GKM scheme is very efficient since it can be implemented by using hash and XOR functions only. Our ReEnc-GKM scheme allows a member to reduce the cost of computing the up-to-date group key to one decryption by outsourcing logN operations. Both of our schemes are shown immune to the collusion attacks. For KeyDer-GKM, a set of collusive members cannot recover an unauthorized group key. For ReEnc-GKM, a set of collusive members cannot distinguish an unauthorized group key from a random string. (C) 2016 Elsevier B.V. All rights reserved.
Scalable multicasting with multiple shared trees in software defined networking
(2017-01-15)
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
Teng, Hung-Yi
;
Liao, Chun-Chieh
;
Kao, Yi-Chih
With Software Defined Networking (SDN), IP multicast becomes promising again. For IPTV applications over SDN, existing works would not scale well since they are based on per-source trees. As control-plane in SDN is logically centralized, constructing multiple shared trees is more feasible than that in traditional IP networks. Thus, in this work, we present a locality-aware multicast approach (LAMA) to construct multi-group shared trees in SDN, where each shared tree covers multiple multicast groups. In LAMA, the controller first clusters the multicast sources located in the vicinity into the same multicast cluster. For each multicast cluster, the controller selects the center switch which has the minimum distance to all multicast sources as its rendezvous point (RP) and then constructs a shortest-path multicast tree from the RP to its hosts. Finally, based on the multi-group shared trees, the controller can establish coarse-grained flow entries into on-tree switches to reduce the number of installed flow entries. Emulations on the Ryu controller and the Mininet emulator show that only 2-5 shared trees would suffice. The computation time in the controller using LAMA is around 70 ms, much less than hundreds ms required for per-source trees. Moreover, LAMA only establishes 2300 flow entries, 4% of that with per-source trees in a large topology.
Adsorption of precious metals in water by dendrimer modified magnetic nanoparticles
(2017-01-15)
Yen, Chia-Hsin
;
Lien, Hsing-Lung
;
Chung, Jung-Shing
;
Yeh, Hund-Der
;
環境工程研究所
Magnetic nanoparticles modified by third-generation dendrimers (MNP-G3) and MNP-G3 further modified by ethylenediaminetetraacetic acid (EDTA) (MNP-G3-EDTA) were conducted to investigate their ability for recovery of precious metals (Pd(IV), Au(III), Pd(II) and Ag(I)) in water. Experiments were carried out using batch reactors for the studies of adsorption kinetics, adsorption isotherms, competitive adsorption and regeneration. The pseudo second-order model is the best-fit model among others suggesting that the adsorption of precious metals by MNP-G3 in water is a chemisorption process. Three adsorption isotherms namely Langmuir, Freundlich and Dubinin-Radushkevich isotherm were examined and the results showed the similarities and consistency of both linear and nonlinear analyses. Pd(IV) and Au(III) with higher valence exhibited relatively better adsorption efficiency than Pd(II) and Ag(I) with lower valence suggesting that the adsorption of precious metals by MNP-G3 is a function of valence. In the presence of the competing ion Zn(II), the adsorption efficiency of MNP-G3 for all four precious metals was declined significantly. The use of MNP-G3-EDTA revealed an increase in the adsorption efficiency for all four precious metals. However, the low selectivity of MNP-G3 towards precious metals was not enhanced by the modification of EDTA onto the MNP-G3. The regeneration of metal-laden MNP-G3 can be readily performed by using 1.0% HCl solution as a desorbent solution. (C) 2016 Elsevier B.V. All rights reserved.
Sound radiation of panel-form loudspeaker using flat voice coil for excitation
(2017-01-15)
Jiang, C. H.
;
Kam, T. Y.
;
Chang, Y. H.
;
機械工程學系
;
Department of Mechanical Engineering
A novel panel-form loudspeaker in which the panel of the speaker is excited by the forces generated through the flat voice coil of a rectangular electro-magnetic type exciter for sound radiation is presented. The exciter when properly designed has the advantage of exerting appropriate loads to the panel so that the major sound pressure level (SPL) dips of the speaker can be suppressed or even eliminated. For designing such panel-form speaker, a method formulated on the basis of the classical plate theory (CPT), Ritz method, and first Rayleigh integral is proposed for predicting the SPL curve of the speaker. An experimental investigation was performed to verify the feasibility of the proposed method. The effects of some system parameters on the major SPL dips of the proposed panel-form speakers are investigated by means of several numerical examples. The optimal locations of flat voice coils for exciting several panel-form speakers are determined to illustrate the important role of excitation location for enhancing sound quality of such speakers via the removal or suppression of the major SPL dips. (C) 2016 Elsevier Ltd. All rights reserved.
Quasi-static buckling and first-ply failure loads of shear web reinforced glass-fabric composite wind blades
(2017-01-15)
Kam, T. Y.
;
Su, H. M.
;
Huang, C. Y.
;
機械工程學系
;
Department of Mechanical Engineering
A procedure is proposed to analyze the structural failure of a composite wind blade subjected to quasi-static loads. The structural failure of a wind blade under extreme wind loads which can be treated as quasi-static loads is an important issue to be tackled when assessing the reliability of a wind turbine. In the proposed structural failure analysis procedure, the geometrically nonlinear finite element (FE) method together with several phenomenological failure criteria is used to investigate the possible failure modes such as incipient buckling, interfacial debonding, and first-ply failure of the blade via an incremental loading approach. The failure loads and locations associated with the possible failure modes for a number of small wind blades with different structural configurations are determined to study the appropriateness of the failure criteria. Static tests of several small glass-fabric composite wind blades were conducted to validate the suitability of the proposed procedure. It has been shown that the experimentally and theoretically predicted failure processes of the wind blades are in good agreement. The applications of the proposed procedure are demonstrated by means of a numerical example in which the failure process of a wind blade under quasi-static wind loads is simulated. (C) 2016 Elsevier Ltd. All rights reserved.
統一隨機性的定理
(國立交通大學丘成桐中心, 2017-01-15)
紀露結　
相異隨機結構背後的深刻幾何連結
專題-秩序與複雜的華爾滋（上）螢火蟲的數學習題
(國立交通大學丘成桐中心, 2017-01-15)
莊重
同步現象的前世今生
因名將而流芳異國的青春之詩
(國立交通大學丘成桐中心, 2017-01-15)
季理真
;
林奕君
兼談數學家的青春情結
Enhanced visible-light-responsive photodegradation of bisphenol A by Cu, N-codoped titanate nanotubes prepared by microwave-assisted hydrothermal method
(2017-01-15)
Doong, Ruey-An
;
Liao, Chun-Yi
;
環境工程研究所
;
Institute of Environmental Engineering
In this study, a rapid and effective microwave-assisted hydrothermal method was developed for the synthesis of Cu, N-codoped titanate nanotubes (Cu, N-TNTs) to enhance the photocatalytic degradation efficiency and rate of bisphenol A (BPA) under UV and visible light irradiations. The TNTs were first synthesized at 150 degrees C for 3 h under microwave heating conditions followed by the calcination at 450 degrees C in the presence of 6 wt% Cu ions and N-2/NH3 to fabricate Cu, N-TNTs composites. The Cu, N-TNTs exhibited excellent photocatalytic activity toward BPA degradation under UV and visible light irradiations. The X-ray photoelectron spectra indicated that Cu species in Cu, N-TNTs were mainly in zerovalent form and could serve as the electron donors as well as shuttling species to accelerate the photodegradation of BPA. In addition, the nitrogen atoms were incorporated into the anatase lattices to increase the visible light-responsive capability. The surface normalized reaction rate constants for BPA degradation were 4.3 and 1.5 times higher than those of Degussa P25 TiO2 under UV and visible light irradiations, respectively. The electron spin resonance spectra showed that Cu, N-codoped TNTs prolonged the generation of oxygen-containing radicals for at least 5 min, resulting in the significant enhancement of photodegradation efficiency and rate of BPA. Results obtained in this study open a new avenue by using simple and effective microwave-assisted hydrothermal method to fabricate low dimensional codoped TNTs which can be potentially applied in a wide variety of fields of purification, green chemistry and photocatalysis. (C) 2016 Elsevier B.V. All rights reserved.
編輯曲線混沌、複雜、隨機中的秩序
(國立交通大學丘成桐中心, 2017-01-15)
編輯室
「淨從穢生」的科學演繹
專題-秩序與複雜的華爾滋（上）從天體力學到混沌理論的形成
(國立交通大學丘成桐中心, 2017-01-15)
陳國璋
龐卡赫無價的美麗錯誤
數理簡訊拓樸相變和拓樸物質
(國立交通大學丘成桐中心, 2017-01-15)
張明強
2016 諾貝爾物理學獎簡介
數理人文第十一期中英文對照
(國立交通大學丘成桐中心, 2017-01-15)
編輯室
中英名詞對照
提升民眾對於數學的知覺
(國立交通大學丘成桐中心, 2017-01-15)
李國偉　
兼記臺灣 IMAGINARY 數學特展