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Strong-form framework for solving boundary value problems with geometric nonlinearity

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Applied Mathematics and Mechanics(English Edition) 2016年第12期37卷 1707-1720页

作者： J.P.YANG W.T.SU Department of Civil Engineering Chiao Tung University

In this paper, we present a strong-form framework for solving the boundary value problems with geometric nonlinearity, in which an incremental theory is developed for the problem based on the Newton-Raphson scheme. Conventionally, the finite ele- ment methods （FEMs） or weak-form based meshfree methods have often been adopted to solve geometric nonlinear problems. However, issues, such as the mesh dependency, the numerical integration, and the boundary imposition, make these approaches com- putationally inefficient. Recently, strong-form collocation methods have been called on to solve the boundary value problems. The feasibility of the collocation method with the nodal discretization such as the radial basis collocation method （RBCM） motivates the present study. Due to the limited application to the nonlinear analysis in a strong form, we formulate the equation of equilibrium, along with the boundary conditions, in an incremental-iterative sense using the RBCM. The efficacy of the proposed framework is numerically demonstrated with the solution of two benchmark problems involving the geometric nonlinearity. Compared with the conventional weak-form formulation, the pro- posed framework is advantageous as no quadrature rule is needed in constructing the governing equation, and no mesh limitation exists with the deformed geometry in the increment al-it erative process.

关键词： geometric nonlinearity incremental-iterative algorithm radial basis collo-cation method (RBCM) strong form

Photocatalytic removal of NO and NO_2 using titania nanotubes synthesized by hydrothermal method

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Journal of Environmental Sciences 2014年第5期26卷 1180-1187页

作者： Nhat Huy Nguyen Hsunling Bai Institute of Environmental Engineering National Chiao Tung University

In this study, the photocatalysts of titania nanotubes （TNTs） were synthesized at different calcination temperatures using commercial Degussa TiO2 （P25） as a precursor. The materials were then characterized by BET, SEM, TEM, and XRD analyses. The photocatalytic reactions with NO and NO2 under UV-A irradiation were both performed. The results showed that the photocatalytic reaction rate of NO was much faster than that of NO2, and the conversion of NO2 to nitrate was the rate-limiting step for photocatalytic removal of NOx if the nitrate produced cannot be removed continuously from the photocatalyst surface. For TNTs calcined at different temperatures, a significant enhancement was observed on the total NOx removal efficiency by TNT calcined at 500℃ for both NO and NO2 photocatalytic reaction, which could be attributed to its high anatase crystallinity as well as high surface area. These two factors affect primarily on the NO2 conversion step in which the high anatase crystallinity could be responsible for the high efficiency at the beginning, while the high surface area could be accounted for retaining this high efficiency from nitric acid poisoning during the test period.

关键词： nitrogen oxides TNTs TiO2 indoor air pollution control environmental photocatalysis

A multi-subwaveform parametric retracker of the radar satellite altimetric waveform and recovery of gravity anomalies over coastal oceans

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Science China Earth Sciences 2010年第4期53卷 610-616页

作者： HWANG CheinWay Department of Civil Engineering Chiao Tung University

The quality of satellite radar altimetric data is very important in studies of geodesy,geophysics,and *** coastal oceans,altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open *** we develop a new multi-subwaveform parametric retracker(MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal *** least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric *** waveform data records from Geosat/GM around Taiwan Island are practically retracked with *** compared with the Taiwan geoid height,the results retracked by MSPR are more accurate than those retracked by the well-known β-5-parmeter method and from the geophysical data records(GDRs).The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares *** we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean,we found that the results from retracked data are more accurate than those from GDRs.

关键词： multi-subwaveform parametric retracker waveform retracking for radar satellite altimetry gravity anomaly least squares collocation Geosat/GM

Optimized evacuation route based on crowd simulation

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Computational Visual Media 2017年第3期3卷 243-261页

作者： Sai-Keung Wong Yu-Shuen Wang Pao-Kun Tang Tsung-Yu Tsai 'National chiao tung university' TaiwanChina

An evacuation plan helps people move away from an area or a building. To assist rapid evacuation,we present an algorithm to compute the optimal route for each local region. The idea is to reduce congestion and maximize the number of evacuees arriving at exits in each time span. Our system considers crowd distribution, exit locations, and corridor widths when determining optimal routes. It also simulates crowd movements during route optimization. As a basis,we expect that neighboring crowds who take different evacuation routes should arrive at respective exits at nearly the same time. If this is not the case, our system updates the routes of the slower crowds. As crowd simulation is non-linear, the optimal route is computed in an iterative manner. The system repeats until an optimal state is achieved. In addition to directly computing optimal routes for a situation, our system allows the structure of the situation to be decomposed,and determines the routes in a hierarchical *** strategy not only reduces the computational cost but also enables crowds in different regions to evacuate with different priorities. Experimental results,with visualizations, demonstrate the feasibility of our evacuation route optimization method.

关键词： crowd simulation evacuation path planning optimization

Efficiency balance of a light guide plate with microstructures for a see-through head-mounted display

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Chinese Optics Letters 2016年第2期14卷 73-77页

作者：趙凱緯潘瑞文 Institute of Lighting and Energy Photonics National Chiao Tung University Institute of Photonic System National Chiao Tung University Biomedical Electronics Translational Research Center National Chiao Tung University Department of Medical Research Chi Mei Medical Center

The efficiency balance phenomenon for see-through head-mounted displays with different microstructure con- ditions can be found both theoretically and using optical simulation software. A simple mathematical calculation is used to determine the relationship between the real image （see-through function） energy and the virtual image energy. The simulation is based on factors taken from previous research studies. It is found that the balance value of the optical efficiency remains almost constant （66.63% to 67.38%） under different microstructure conditions. In addition, suitable conditions for the microstructures in see-through head-mounted displays for daily applications can be predicted.

关键词： Efficiency balance of a light guide plate with microstructures for a see-through head-mounted display head

An accelerated K-means clustering algorithm using selection and erasure rules

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Journal of Zhejiang university-Science C(Computers and Electronics) 2012年第10期13卷 761-768页

作者： Suiang-Shyan LEE Ja-Chen LIN Department of Computer Science National Chiao Tung University

The K-means method is a well-known clustering algorithm with an extensive range of applications,such as biological classification,disease analysis,data mining,and image ***,the plain K-means method is not fast when the number of clusters or the number of data points becomes large.A modified K-means algorithm was presented by Fahim et al.(2006).The modified algorithm produced clusters whose mean square error was very similar to that of the plain K-means,but the execution time was *** this study,we try to further increase its *** are two rules in our method:a selection rule,used to acquire a good candidate as the initial center to be checked,and an erasure rule,used to delete one or many unqualified centers each time a specified condition is *** clustering results are identical to those of Fahim et al.(2006).However,our method further cuts computation time when the number of clusters *** mathematical reasoning used in our design is included.

关键词： K-means clustering Acceleration Vector quantization Selection Erasure

Optical cross-talk reduction in a quantumdot-based full-color micro-light-emitting-diode display by a lithographic-fabricated photoresist mold

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Photonics Research 2017年第5期5卷 411-416页

作者： HUANG-YU LIN CHIN-WEI SHER DAN-HUA HSIEH XIN-YIN CHEN HUANG-MING PHILIP CHEN TENG-MING CHEN KEI-MAY LAU CHYONG-HUA CHEN CHIEN-CHUNG LIN HAO-CHUNG KUO Department of Photonics and Institute of Electro-Optical Engineering National Chiao Tung University Department of Applied Chemistry National Chiao Tung University Department of Electric and Computer Engineering Hong Kong University of Science and Technology Institute of Photonic System National Chiao Tung University

In this study, a full-color emission red–green–blue(RGB) quantum-dot(QD)-based micro-light-emitting-diode(micro-LED) array with the reduced optical cross-talk effect by a photoresist mold has been demonstrated. The UV micro-LED array is used as an efficient excitation source for the QDs. The aerosol jet technique provides a narrow linewidth on the micrometer scale for a precise jet of QDs on the micro-LEDs. To reduce the optical cross-talk effect,a simple lithography method and photoresist are used to fabricate the mold, which consists of a window for QD jetting and a blocking wall for cross-talk reduction. The cross-talk effect of the well-confined QDs in the window is confirmed by a fluorescence microscope, which shows clear separation between QD pixels. A distributed Bragg reflector is covered on the micro-LED array and the QDs' jetted mold to further increase the reuse of UV *** enhanced light emission of the QDs is 5%, 32%, and 23% for blue, green, and red QDs, respectively.

关键词： QDs Optical cross-talk reduction in a quantumdot-based full-color micro-light-emitting-diode display by a lithographic-fabricated photoresist mold

Experimental and numerical studies of micro PEM fuel cell

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Acta Mechanica Sinica 2011年第5期27卷 627-635页

作者： Rong-Gui Peng Chen-Chung Chung Chiun-Hsun Chen Department of Mechanical Engineering National Chiao Tung UniversityHsinchu Taiwan China

A single micro proton exchange membrane fuel cell （PEMFC） has been produced using Micro-electromechanical systems （MEMS） technology with the active area of 2.5 cm 2 and channel depth of about 500 μ m.A theoretical analysis is performed in this study for a novel MEMS-based design of a micro *** model consists of the conservation equations of mass,momentum,species and electric current in a fully integrated finite-volume solver using the CFD-ACE＋ commercial *** polarization curves of simulation are well correlated with experimental ***-dimensional simulations are carried out to treat prediction and analysis of micro PEMFC temperature,current density and water distributions in two different fuel flow rates （15 cm 3 /min and 40 cm 3 /min）.Simulation results show that temperature distribution within the micro PEMFC is affected by water distribution in the membrane and indicate that low and uniform temperature distribution in the membrane at low fuel flow rates leads to increased membrane water distribution and obtains superior micro PEMFC current density distribution under 0.4 V operating *** predictions are well within those known for experimental mechanism phenomena.

关键词： Micro PEMFC · MEMS · Simulation · Fuel flow rate

Numerical analyses and experiment investigations of an annular micro gas turbine power system using fuels with low heating values

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Science China(Technological Sciences) 2009年第12期52卷 3565-3579页

作者： YANG ChunHsiang LEE ChengChia HSIAO JenHao CHEN ChiunHsun Department of Mechanical Engineering ‘National’Chiao Tung University

This study investigates the effects of using fuels with low heating values on the performance of an annular micro gas turbine(MGT)experimentally and *** MGT used in this study is MW-54, whose original fuel is liquid(Jet A1).Its fuel supply system is re-designed to use biogas fuel with low heating value(LHV).The purpose is to reduce the size of a biogas distributed power supply system and to enhance its *** study assesses the practicability of using fuels with LHVs by using various mixing ratios of methane(CH4)and carbon dioxide(CO2).Prior to experiments,the corresponding simulations,aided by the commercial code CFD-ACE+,were carried out to investigate the cooling effect in a perforated combustion chamber and combustion behavior in an annular MGT when LHV gas was *** main purposes are to confirm that there are no hot spots occurring in the liners and the exhaust temperatures of combustor are lower than 700°C when MGT is operated under different *** experiments,fuel pressure and mass flow rate,turbine rotational speed,generator power output,and temperature distribution were measured to analyze MGT *** results indicate that the presented MGT system operates successfully under each tested condition when the minimum heating value of the simulated fuel is approximately 50%of pure *** power output is around 170 W at 85000 r/min as 90%CH4 with 10%CO2 is used and 70 W at 60000 r/min as 70%CH4 with 30%CO2 is *** a critical limit of 60%CH4 is used,the power output is extremely low. Furthermore,the best theoretical Brayton cycle efficiency for such MGT is calculated as 23%according to the experimental data while LHV fuel is ***,the numerical results and experiment results reveal that MGT performance can be improved further and the possible solutions for performance im- provement are suggested for the future studies.

关键词： numerical analyses experiment investigations annular micro gas turbine low heating values