Browsing by Issue Date, starting with "2016-04-05"

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Analytical analysis and experimental verification of trapezoidal fin for assessment of heat sink performance and material saving
(2016-04-05)
Chen, Hong-Long
;
Wang, Chi-Chuan
;
機械工程學系
;
Department of Mechanical Engineering
A quick assessment of the performance loss in association with material saving amid rectangular and trapezoidal fin is analytically investigated and experimentally verified. A novel dimensionless parameter - r(t) representing the ratio of the fin tip to base thickness - is used to simplify the fin equation. A dimensionless differential equation is derived based on the formulation and the corresponding closed form solution of the dimensionless temperature and fin efficiency is presented. It is found that the performance drop depends on various rt ratios, and the most pronounced performance difference occurs in the region between M = 1.7 and 2.5. Yet the performance difference between the rectangular and trapezoidal fin are quite insignificant at low velocity region; with the increasing of velocity, the performance loss ratio is gradually discriminated to reach the maximum performance loss between region of M = 1 and 2, then it begins to converge again toward M = 4. The recovering of the ratio is actually associated with the diverging and converging trend of the fin efficiency. The analytical results are in line with the experimental results. At a frontal velocity of 4 m/s, the predicted difference of heat transfer rate between trapezoidal and rectangular fin profile in terms of total heat transfer ratio is only 0.88%. (C) 2015 Elsevier Ltd. All rights reserved.
Increased risks of tic disorders in children with epilepsy: A nation-wide population-based case control study in Taiwan
(2016-04-05)
Weng, Wen-Chin
;
Huang, Hui-Ling
;
Wong, Lee Chin
;
Jong, Yuh-Jyh
;
Yin, Yun-Ju
Both epilepsy and tic disorders may share common mechanisms with the involvement of abnormal cortical-basal ganglion circuit connection and dopaminergic dysfunction. However, the association between epilepsy and tic disorders has never been studied. This study investigated the risks of developing tic disorders among children with epilepsy using databases of a universal health insurance system in Taiwan. The data analyzed in this study were retrieved from the National Health Insurance Research Database in Taiwan. The study cohort included children with epilepsy between 2001 and 2007 (n = 2629) and a three-fold age- and gender-matched controls (n = 7887). All subjects were followed up for 3 years from the date of cohort entry to identify their admissions due to tic disorders (ICD-9-CM codes 307.2, 307.20-307.23). Cox hazard regression analysis was performed to estimate the effect of epilepsy on the occurrence of tics. The epilepsy cohort had a higher prevalence of tics (1.7% vs. 0.2%), and a 8.70-fold increased risk of developing a tic disorder compared with the controls (adjusted hazard ratio (AHR) 8.70, 95% confidence interval (CI) 4.26-16.37, p < 0.001). Male patients were observed to have a higher risk of developing a tic disorder (AHR 1.90, 95% CI = 1.04-3.46, p < 0.001) compared to female individuals. Patients with multiple antiepileptic drugs treatment also exhibited higher crude OR for developing tic disorders. This nationwide population-based cohort study, for the first time, demonstrated that there is a significantly increased risk for tic disorders among children with epilepsy. We also found males, attention deficit disorder and the use of multiple AEDs to be independent risk factors of tic disorders. Closely evaluating possible tic disorders would be crucial for improving the outcome and life quality in children with epilepsy. (C) 2015 Elsevier Ltd. All rights reserved.
An experimental and analytical investigation of the photo-thermal-electro characteristics of a high power InGaN LED module
(2016-04-05)
Yang, Kai-Shing
;
Ding, Wei-Ting
;
Yeh, Chih-Ting
;
Lee, Ming-Tsang
;
Wang, Chi-Chuan
The photo-thermal-electro characteristics of a high power InGaN LED module were studied both experimentally and theoretically. Three types of heat sink substrate composed of two layers of materials were used to investigate the coupled relationships between chip temperature, thermal resistance, input electric power and light emission efficiency. The results showed that the thermal spreading resistance accounts for a significant fraction of the total substrate thermal resistance. The measured thermal resistance of the LED module increased with rising electric power input. Luminescent efficacy measurements revealed that this increase of thermal resistance was the result of increased heat dissipation from the chip due to less efficient conversion of electric power to light output. Furthermore, experimental results showed that the radiant efficiency of the LED decreases with increasing input electric power. The coupled effects of chip temperature, input power and thermal resistance of the substrate are responsible for this efficiency droop. A revised model for estimating the luminous efficacy that takes both thermal and electrical effects into consideration is proposed. It is shown that the efficiency droop of the LED module for all three types of substrates can be clearly demonstrated by using the proposed analysis. (C) 2015 Elsevier Ltd. All rights reserved.
Evaluation of thermal performance of packaged GaN HEMT cascode power switch by transient thermal testing
(2016-04-05)
Chen, Szu-Hao
;
Chou, Po-Chien
;
Cheng, Stone
;
機械工程學系
;
Department of Mechanical Engineering
In this investigation, thermal transient measurements and analyses are used to study the thermal performance of a cascoded GaN power device. The method is based on the thermal characterization of the on-resistance (R-on) of the device and the synchronized current-voltage characteristics under continuous operation. The changes in R-on with temperature (25 degrees C-180 degrees C) are measured, statistically studied, and correlations investigated. The proposed method for estimating transient thermal impedance has the following characteristics: (1) it is robust and reproducible; (2) it yields a heating curve to prevent overheating for the device under test (DUT); (3) it provides in-situ current-voltage characterization; (4) it includes a transient offset correction for initial transient electrical disturbances (such as current collapse); (5) it optimizes a compact thermal model; (6) it is sensitive to package structure and design variables. This monitoring of thermal impedance variation provides a simple and fast non-destructive method for analyzing power switching devices during thermal testing. Satisfactory experimental results confirm the feasibility of in-situ current-voltage characterization and the real power varies with the thermal impedance. (C) 2015 Elsevier Ltd. All rights reserved.
Increased risk of epilepsy in children with Tourette syndrome: A population-based case-control study
(2016-04-05)
Wong, Lee Chin
;
Huang, Hui-Ling
;
Weng, Wen-Chin
;
Jong, Yuh-Jyh
;
Yin, Yun-Ju
The association between epilepsy and Tourette syndrome has rarely been investigated. In this retrospective cohort study, we analyzed a dataset of 1,000,000 randomly sampled individuals from the Taiwan National Health Insurance Research Database to determine the risk of epilepsy in children with Tourette syndrome. The study cohort consisted of 1062 patients with Tourette syndrome aged <= 18 years, and the control group consisted of three times the number of age- and sex-matched patients without Tourette syndrome, who were insurants, from the same database during the same period. The Tourette syndrome group had an 18.38-fold increased risk of epilepsy than the control group [hazard ratio = 18.38, 95% confidence interval (Cl) = 8.26-40.92; P < 0.001]. Even after adjusting for the comorbidities, the risk of epilepsy in the Tourette syndrome group with comorbidities remained high (hazard ratio = 16.27, 95% CI = 6.26-18.46; P < 0.001), indicating that the increased risk was not associated with comorbidities. This population-based retrospective cohort study provides the first and strong evidence that Tourette syndrome is associated with a higher risk of epilepsy. A close follow-up of children with Tourette syndrome for the development of epilepsy is warranted. (C) 2015 Elsevier Ltd. All rights reserved.
Monolithic 3D CMOS Using Layered Semiconductors
(2016-04-06)
Sachid, Angada B.
;
Tosun, Mahmut
;
Desai, Sujay B.
;
Hsu, Ching-Yi
;
Lien, Der-Hsien
Monolithic 3D integrated circuits using transition metal dichalcogenide materials and low-temperature processing are reported. A variety of digital and analog circuits are implemented on two sequentially integrated layers of devices. Inverter circuit operation at an ultralow supply voltage of 150 mV is achieved, paving the way to high-density, ultralow-voltage, and ultralow-power applications.
Guest Editorial: Special Section on Emerging Topics in the Design of High Performance Internet Routers
(2016-04-06)
Tseng, Yu-Chee
;
Hsieh, Sun-Yuan
;
資訊工程學系
;
Department of Computer Science
交大e-News第206期-大專盃嶄露頭角交大女籃九場全勝奪冠
(2016-04-06)
國立交通大學秘書室
;
Secretariat
Measurement of Cosmic-ray Muon-induced Spallation Neutrons in the Aberdeen Tunnel Underground Laboratory
(2016-04-06)
Blyth, S. C.
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Chan, Y. L.
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Chen, X. C.
;
Chu, M. C.
;
Cui, K. X.
Muon-induced neutrons are one of the major backgrounds to various underground experiments, such as dark matter searches, low-energy neutrino oscillation experiments and neutrino-less double beta-decay experiments. Previous experiments on the underground production rate of muon-induced neutrons were mostly carried out either at shallow sites or at very deep sites. The Aberdeen Tunnel experiment aims to measure the neutron production rate at a moderate depth of 611 meters water equivalent. Our apparatus comprises of six layers of plastic-scintillator hodoscopes for tracking the incident cosmic-ray muons, and 760 L of gadolinium-doped liquid-scintillator for both neutron production and detection targets. In this paper, we describe the design and the performance of the apparatus. The preliminary result on the measurement of neutron production rate is also presented.
The Dark Matter Self-Interaction and Its Impact on the Critical Mass for Dark Matter Evaporations Inside the Sun
(2016-04-06)
Chen, Chian-Shu
;
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Lin, Yen-Hsun
;
物理研究所
We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 similar to 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels chi chi -> tau(+)tau(-), nu(nu) over bar as examples. The PINGU sensitivities to DM self-interaction cross section sigma(chi chi) are estimated for track and cascade events.
Photoisomerization mechanisms from trans, trans-1,4-diphenyl-1,3-butadiene: CASSCF on-the-fly trajectory surface hopping dynamic simulations
(2016-04-07)
Zheng, Xiaolei
;
Zhai, Gaohong
;
Gao, Wanqing
;
Lei, Yibo
;
Yu, Le
We have employed the SA2-CAS(4,4)/6-31G ab initio method together with an on-the-fly global-switching trajectory surface hopping algorithm to simulate photoisomerization reaction dynamics from reactant trans, trans-1,4-diphenyl-1,3-butadiene (DPB) to products cis,trans-DPB and cis,cis-DPB. This topic has been extensively studied experimentally and the present theoretical study is the first to simulate DPB photoisomerization reaction dynamics as far as we know. With total 600 sampling trajectories, 300 actively contribute to isomerization reaction via two conical intersections between the electronic ground and the first excited states. Simulated quantum yields of photoisomerization to cis, trans-DPB and cis, cis-DPB are 0.09 and 0.045, which are in good agreement with the experimental values of 0.07-0.25 and 0.02, respectively. The lifetime of the first excited state is estimated as 702 fs. The present simulation has shown two reactive photoisomerization mechanisms, namely one bond twist (OBT) and bicycle pedal (BP), and two non-reactive photoisomerization mechanisms, namely single bond torsion (SBT) and reverse torsion (RT) with respect to the central backbone CC bonds. We believe that the present theoretical work can benefit the experiments on photoisomerization of DPB derivates.
Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory
(2016-04-07)
Blyth, S. C.
;
Chan, Y. L.
;
Chen, X. C.
;
Chu, M. C.
;
Cui, K. X.
We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be I-mu = (5.7 +/- 0.6) x 10(-6) cm(-2) s(-1) sr(-1). The yield of muon-induced neutrons in the liquid scintillator was determined to be Y-n = (1.19 +/- 0.08(stat) +/- 0.21(syst)) x 10(-4) neutrons/(mu.g.cm(-2)). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of < E-mu >(0.76 +/- 0.03) for liquid-scintillator targets.
Extremal RN/CFT in both hands revisited
(2016-04-10)
Kuo, En-Jui
;
Yang, Yi
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電子物理學系
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Department of Electrophysics
We study RN/CFT correspondence for four dimensional extremal Reissner-Nordstrom black hole. We uplift the 4d RN black hole to a 5d rotating black hole and make a geometric regularization of the 5d space-time. Both hands central charges are obtained correctly at the same time by Brown-Henneaux technique. (C) 2016 The Authors. Published by Elsevier B.V.
Restoring electronic coherence/decoherence for a trajectory-based nonadiabatic molecular dynamics
(2016-04-11)
Zhu, Chaoyuan
;
應用化學系分子科學碩博班
;
Institute of Molecular science
By utilizing the time-independent semiclassical phase integral, we obtained modified coupled time-dependent Schrodinger equations that restore coherences and induce decoherences within original simple trajectory-based nonadiabatic molecular dynamic algorithms. Nonadiabatic transition probabilities simulated from both Tully's fewest switches and semiclassical Ehrenfest algorithms follow exact quantum electronic oscillations and amplitudes for three out of the four well-known model systems. Within the present theory, nonadiabatic transitions estimated from statistical ensemble of trajectories accurately follow those of the modified electronic wave functions. The present theory can be immediately applied to the molecular dynamic simulations of photochemical and photophysical processes involving electronic excited states.
Helical Majorana fermions in d(x2-y2) + id(xy)-wave topological superconductivity of doped correlated quantum spin Hall insulators
(2016-04-11)
Sun, Shih-Jye
;
Chung, Chung-Hou
;
Chang, Yung-Yeh
;
Tsai, Wei-Feng
;
Zhang, Fu-Chun
There has been growing interest in searching for exotic self-conjugate, charge-neutral low-energy fermionic quasi-particles, known as Majorana fermions (MFs) in solid state systems. Their signatures have been proposed and potentially observed at edges of topological superconcuctors with non-trivial topological invariant in the bulk electronic band structure. Much effort have been focused on realizing MFs in odd-parity superconductors made of strong spin-orbit coupled materials in proximity to conventional superconductors. In this paper, we propose a novel mechanism for realizing MFs in 2D spin-singlet topological superconducting state induced by doping a correlated quantum spin Hall (Kane-Mele) insulator. Via a renormalized mean-field approach, the system is found to exhibits time-reversal symmetry (TRS) breaking d(x2-y2) + id(xy)-wave (chiral d-wave) superconductivity near half-filling in the limit of large on-site repulsion. Surprisingly, however, at large spin-orbit coupling, the system undergoes a topological phase transition and enter into a new topological phase protected by a pseudo-spin Chern number, which can be viewed as a persistent extension of the quantum spin Hall phase upon doping. From bulk-edge correspondence, this phase is featured by the presence of two pairs of counter-propagating helical Majorana modes per edge, instead of two chiral propagating edge modes in the d + id' superconductors.
A high performance transparent resistive switching memory made from ZrO2/AlON bilayer structure
(2016-04-11)
Tsai, Tsung-Ling
;
Chang, Hsiang-Yu
;
Lou, Jesse Jen-Chung
;
Tseng, Tseung-Yuen
;
電子工程學系及電子研究所
In this study, the switching properties of an indium tin oxide (ITO)/zirconium oxide (ZrO2)/ITO single layer device and those of a device with an aluminum oxynitride (AlON) layer were investigated. The devices with highly transparent characteristics were fabricated. Compared with the ITO/ZrO2/ITO single layer device, the ITO/ZrO2/AlON/ITO bilayer device exhibited a larger ON/OFF ratio, higher endurance performance, and superior retention properties by using a simple two-step forming process. These substantial improvements in the resistive switching properties were attributed to the minimized influence of oxygen migration through the ITO top electrode (TE), which can be realized by forming an asymmetrical conductive filament with the weakest part at the ZrO2/AlON interface. Therefore, in the ITO/ZrO2/AlON/ITO bilayer device, the regions where conductive filament formation and rupture occur can be effectively moved from the TE interface to the interior of the device. Published by AIP Publishing.
Organic Photovoltaics and Bioelectrodes Providing Electrical Stimulation for PC12 Cell Differentiation and Neurite Outgrowth
(2016-04-13)
Hsiao, Yu-Sheng
;
Liao, Yan-Hao
;
Chen, Huan-Lin
;
Chen, Peilin
;
Chen, Fang-Chung
Current bioelectronic medicines for neurological therapies generally involve treatment with a bioelectronic system comprising a power supply unit and a bioelectrode device. Further integration of wireless and self-powered units is of practical importance for implantable bioelectronics. In this study, we developed biocompatible organic photovoltaics (OPVs) for serving as wireless electrical power supply units that can be operated under illumination with near-infrared (NIR) light, and organic bioelectronic interface (OBEI) electrode devices as neural stimulation electrodes. The OPV/OBEI integrated system is capable to provide electrical stimulation (ES) as a means of enhancing neuron-like PC12 cell differentiation and neurite outgrowth. For the OPV design, we prepared devices incorporating two photoactive material systems-beta-carotene/N,N\'-dioctyl-3,4,9,10-perylenedicarboximide (beta-carotene/PTCDI-C8) and poly(3-hexylthiophene)/phenyl-C-61-butyric acid methyl ester (P3HT/PCBM)-that exhibited open circuit voltages of 0.11 and 0.49 V, respectively, under NIR light LED (NLED) illumination. Then, we connected OBEI devices with different electrode gaps, incorporating biocompatible poly(hydroxymethylated-3,4-ethyl-enedioxythiophene), to OPVs to precisely tailor the direct current electric field conditions during the culturing of PC12 cells. This NIR light-driven OPV/OBEI system could be engineered to provide tunable control over the electric field (from 220 to 980 mV mm(-1)) to promote 64% enhancement in the neurite length, direct the neurite orientation on chips, or both. The OPV/OBEI integrated systems under NIR illumination appear to function as effective power delivery platforms that should meet the requirements for wirelessly offering medical ES to a portion of the nervous system; they might also be a key technology for the development of next-generation implantable bioelectronics.
Synthesis and Luminescence Properties of Novel Ce3+- and Eu2+-Doped Lanthanum Bromothiosilicate La3Br(SiS4)(2) Phosphors for White LEDs
(2016-04-13)
Lee, Szu-Ping
;
Liu, Shuang-De
;
Chan, Ting-Shan
;
Chen, Teng-Ming
;
應用化學系
Novel Ce3+- and Eu2+-doped lanthanum bromothiosilicate La3Br(SiS4)(2):Ce3+ and La3Br(SiS4)(2):Eu2+ phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)(2):Ce3+ phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)(2):Eu2+ phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)(2):Ce3+ and La3Br(SiS4)(2):Eu2+ phosphors from 20 to 200 degrees C were investigated. The combination of a 450 nm blue InGaN-based LED chip with the red-emitting La3Br(SiS4)(2):Eu2+ phosphor, and green-emitting BOSE:Eu2+ commercial phosphor produced a warm-white light with the CRI value of similar to 95 and the CCT of 5,120 K. Overall, these results show that the prepared phosphors may have potential applications in pc-WLED.
清代數學家與經學家竟能鼎足而立
(國立交通大學丘成桐中心, 2016-04-15)
蘇俊鴻
從學術贊助看清代數學家專業與地位的提升
無窮小掀起大劇變
(國立交通大學丘成桐中心, 2016-04-15)
洪萬生
評論《無限小：一個危險的數學理論如何形塑現代世界》