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Luminescence properties of YAl_3(BO_3)_4 phosphors doped with Eu^(3+) ions

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Journal of Rare Earths 2008年第6期26卷 792-794页

作者：李桂芳曹全喜李智敏黄云霞 School of technical Physics Xidian University

YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.

关键词： YAl3(BO3)4:Eu^3+ solid state reaction luminescence phosphors rare earths

Relativity and impossibility of superluminal motion

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Chinese Physics B 2012年第11期21卷 63-67页

作者：张启仁 Department of technical Physics Peking University

I prove that not only particle motion but also wave propagation cannot be faster than light according to relativity.

关键词： micro particles wave propagation impossibility of superluminal motion

A robust WENO scheme for nonlinear waves in a moving reference frame

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Journal of Hydrodynamics 2016年第3期28卷 482-488页

作者： Stavros KONTOS Harry B.BINGHAM Ole LINDBERG Allan P.ENGSIG-KARUP Department of Mechanical Engineering Technical University of DenmarkDenmark Department of Applied Mathematics and Computer Science Technical University of DenmarkDenmark

For robust nonlinear wave simulation in a moving reference frame, we recast the free surface problem in Hamilton-Jacobi form and propose a Weighted Essentially Non-Oscillatory （WENO） scheme to automatically handle the upwinding of the convective term. A new automatic procedure for deriving the linear WENO weights based on a Taylor series expansion is introduced. A simplified smoothness indicator is proposed and is shown to perform well. The scheme is combined with high-order explicit Runge-Kutta time integration and a dissipative Lax-Friedrichs-type flux to solve for nonlinear wave propagation in a moving frame of reference. The WENO scheme is robust and less dissipative than the equivalent order upwind-biased finite difference scheme for all ratios of frame of reference to wave propagation speed tested. This provides the basis for solving general nonlinear wave-structure interaction problems at forward speed.

关键词： nonlinear waves Weighted Essentially Non-Oscillatory (WENO) finite difference

A CAD-compatible body-fitted particle generator for arbitrarily complex geo-metry and its application to wave-structure interaction

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Journal of Hydrodynamics 2021年第2期33卷 195-206页

作者： Yujie Zhu Chi Zhang Yongchuan Yu Xiangyu Hu Department of Mechanical Engineering Technical University of MunichGarchingGermany Department of Aerospace and Geodesy Technical University of MunichTaufkirchenGermany

Generating body-fitted particle distribution for arbitrarily complex geometry underpins the applications of particle-based method to engineering and bioengineering and is highly challenging,and thus hinders the potential of particle *** this paper,we present a new computer-aided design(CAD)compatible body-fitted particle generator,termed as CAD-BPG,for arbitrarily complex 3-D *** parsing a CAD model,the present method can accurately tackle arbitrarily complex geometry representation and describe the corresponding geometry surface by constructing an implicit zero level-set function on Cartesian background *** achieve a body-fitted and isotropic particle distribution,physics-driven relaxation process with surface bounding governed by the transport-velocity formulation of smoothed particle hydrodynamics(SPH)methodology is conducted to characterize the particle evolution.A set of examples,ranging from propeller,stent structures and anatomical heart models,show simplicity,accuracy and versatility of the present CAD-BPG for generating body-fitted particle distribution of arbitrarily complex 3-D *** but not least,the present CAD-BPG is applied for modeling wave-structure interaction,where wave interaction with an oscillating wave surge converter is studied,and the results show that the present method not only provides an efficient and easy-to-implement pre-processing tool for particle-based simulation but also improves the numerical accuracy compared with lattice particle ***,the propose CAD-BPG sheds light on simulating real-world applications by particle-based methods for researchers and engineers.

关键词： CAD-compatible body-fitted particle distribution level-set

Monte Carlo study of single-barrier structure based on exclusion model full counting statistics

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Chinese Physics B 2011年第1期20卷 553-556页

作者：陈华杜磊曲成立何亮陈文豪孙鹏 School of technical Physics Xidian University

Different from the usual full counting statistics theoretical work that focuses on the higher order cumulants computation by using cumulant generating function in electrical structures, Monte Carlo simulation of single-barrier structure is performed to obtain time series for two types of widely applicable exclusion models, counter-flows model, and tunnel model. With high-order spectrum analysis of Matlab, the validation of Monte Carlo methods is shown through the extracted first four cumulants from the time series, which are in agreement with those from cumulant generating function. After the comparison between the counter-flows model and the tunnel model in a single barrier structure, it is found that the essential difference between them consists in the strictly holding of Pauli principle in the former and in the statistical consideration of Pauli principle in the latter.

关键词： Monte Carlo simulation higher order cumulant exclusion model full counting statistics

Clustering and classification of energy meter data: A comparison analysis of data from individual homes and the aggregated data from multiple homes

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Building Simulation 2021年第1期14卷 103-117页

作者： Juan Sala Rongling Li Morten H.Christensen Department of Civil Engineering Technical University of DenmarkLyngbyDenmark Department of Electrical Engineering Technical University of DenmarkLyngbyDenmark

The transition towards a more sustainable environment requires the development of new control systems on the demand side to integrate renewable energy sources into the energy *** this purpose,energy meter data of homes have been broadly used in modelling,forecast and optimal control of energy ***,usability and reliability of household energy meter data have not been specifically *** this study,we apply commonly used machine learning methods on the heating consumption data of(1)two individual homes in an apartment building and(2)the district heating substation of the apartment building which includes 72 homes,to identify how the characteristics of data affect the result of data *** clustering approaches were applied using the K-means algorithm to group similar heating daily *** the clustering results,different classification algorithms such as logistic regression and random forest were applied to predict the heating consumption level with regards to the weather *** data analysis process showed that the substation data which is the aggregated heating consumption of the 72 homes is more reliable and valid for energy prediction than the data from two individual *** is due to the large variation and uncertainty in the daily energy use of individual homes.

关键词： smart meter data daily profile clustering classification data usability heat substation

Interaction of TATB with Cu and Cu^(+1). A DFT study

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Defence Technology（防务技术） 2019年第1期15卷 27-37页

作者： Lemi Türker Middle East technical university Department of Chemistry

Symmetric triaminotrinitrobenzene known as TATB decomposes in contact with some heavy metals,such as copper. Presently, TATB and some of its important tautomers are subjected to B3LYP/6-31G(d,p) level of treatment. Some molecular orbital energies have been obtained and compared. Then. interaction of these species with Cu and Cu^+ are investigated. Although TATB has been found to be affected little by either Cu or Cu^+, undergoing only some bond length changes and/or distortions, the resonance-assisted tautomers having one to three aci groups decompose by the influence of Cu atom. In each case, only one N-OH bond rupture occurs.

关键词： Triaminitrinitrobenzene TATB Tautomerism Copper DFT Pull-push

Comparison of three methods for natural gas dehydration

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Journal of Natural Gas Chemistry 2011年第5期20卷 471-476页

作者： Michal Netusil Pavel Ditl Department of Process Engineering Czech technical university

This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.

关键词： gas reservoir underground gas storage natural gas gas dehydration

A method for calculating damage evolution in adiabatic shear band of titanium alloy

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中国有色金属学会会刊：英文版 2009年第5期19卷 1280-1285页

作者：王学滨 College of Mechanics and Engineering Liaoning Technical University

A method for calculating the evolution of the local damage variable at the adiabatic shear band(ASB)center was *** the present method,the JOHNSON-COOK model and the nonlocal theory were adopted,and the damage variable formula applicable for the bilinear(linearly elastic and strain-softening)constitutive relation was further generalized to consider the plastic deformation occurring in the strain-hardening *** at Ti-6Al-4V,the effect of strain rate on the evolution of the local damage variable at the ASB center was *** addition,a parametric study was carried out,including the effects of strain-hardening exponent,strain rate sensitive coefficient,thermal-softening exponent,static shear strength,strain-hardening modulus,shear elastic modulus,work to heat conversion factor,melting temperature and initial *** damage extent at the ASB center in the radial collapse experiment was *** is found that at higher strain rates the damage in the ASB becomes more serious at the same average plastic shear strain of the ASB.

关键词：绝热剪切带损伤变量钛铝合金演化方法计算应变速率敏感系数应变软化硬化指数