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Phase behavior of undecane–tetradecane mixtures confned in SBA-15

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Chinese Chemical Letters 2013年第10期24卷 885-888页

作者： xiao Yan xiao-zheng Lan College of Chemistry and Materials Science Shandong Agriculture University

Phase behavior of undecane-tetradecane （n-C11H24-C14H3o, C11-C14） mixtures in bulk and confined in SBA-15 have been studied using differential scanning calorimetry. The bulk C11-C14 system shows multiple phase regions due to rotator phase. Confined in the pores of SBA-15 （pore diameters 3.8- 7.8 rim）, the mixtures only show a melting boundary of a straight line and a curve, respectively. In SBA- 15 （ 17.2 nm）, phase behavior of the mixtures has some similarity to that of the bulk. Under confinement, the phase diagrams of the mixtures vary with the pore size, temperature, and compositions.

关键词： Confinement Undecane-tetradecanemixtures Size effect Phase diagram

Time-dependent density-functional theory for open electronic systems

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Science China Chemistry 2014年第1期57卷 26-35页

作者： zheng xiao WANG RuLin Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Department of Physics University of Science and Technology of China

Time-dependent density-functional theory(TDDFT)has been successfully applied to predict excited-state properties of isolated and periodic ***,it cannot address a system coupled to an environment or whose number of electrons is not *** tackle these problems,TDDFT needs to be extended to accommodate open *** paper provides a comprehensive account of the recent developments of TDDFT for open systems(TDDFT-OS),including both theoretical and practical *** practicality and accuracy of a latest TDDFT-OS method is demonstrated with two numerical examples:the time-dependent electron transport through a series of quasi-one-dimensional atomic chains,and the real-time electronic dynamics on a two-dimensional graphene *** advancement of TDDFT-OS may lead to promising applications in various fields of chemistry,including energy conversion and heterogeneous catalysis.

关键词： time-dependent density functional theory,real-time electronic dynamics,hierarchical equations of motion

Blow up of Solutions for a Nonlinear Petrovsky Type Equation with Time-dependent Coefficients

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Acta Mathematicae Applicatae Sinica 2020年第4期36卷 836-846页

作者： xiao-xiao zheng Ya-dong SHANG xiao-ming PENG School of Mathematical Sciences Qufu Normal UniversityQufu 273155China School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006China School of Statistics and Mathematics Guangdong University of Finance and EconomicsGuangzhou 510320China

4In this paper,we study a nonlinear Petrovsky type equation with nonlinear weak damping,a superlinear source and time-dependent coefficients utt+△^2u-ki(t)|ut|m^2ut=k2(t)|u|^p-2u,x∈Ω,t>0,whereΩis a bounded domain in R^*** certain conditions on k1(t),k2(t)and the initial-boundary data,the upper bound for blow-up time of the solution with negative initial energy function is given by means of an auxiliary functional and an energy estimate met hod if p>***,a lower bound of blow-up time are obtained by using a Sobolev-type inequality and a first order differential inequality technique for n=2,3 and n>4.

关键词： nonlinear Petrovsky type equation time-dependent coefficients blow-up upper bound lower bound

Derivation of a second-order model for Reynolds stress using renormalization group analysis and the two-scale expansion technique

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Acta Mechanica Sinica 2011年第5期27卷 649-659页

作者： xiao-Hong Wang zheng-Feng Liu xiao-Xia Lu Department of Thermal Science and Energy Engineering University of Science and Technology of China230026 Hefei China

With the two-scale expansion technique proposed by Yoshizawa,the turbulent fluctuating field is expanded around the isotropic *** a low-order two-scale expansion,applying the mode coupling approximation in the Yakhot-Orszag renormalization group method to analyze the fluctuating field,the Reynolds-average terms in the Reynolds stress transport equation,such as the convective term,the pressure-gradient-velocity correlation term and the dissipation term,are *** numerical examples：turbulent flow past a backward-facing step and the fully developed flow in a rotating channel,are presented for testing the efficiency of the proposed second-order *** these two numerical examples,the proposed model performs as well as the Gibson-Launder （GL） model,giving better prediction than the standard k-ε model,especially in the abilities to calculate the secondary flow in the backward-facing step flow and to capture the asymmetric turbulent structure caused by frame rotation.

关键词： Turbulent modeling Renormalization group Two-scale expansion Reynolds stress transport equation Second-order model

Effects of phase change material(PCM)-based nanocomposite additives on thermal decomposition and burning characteristic of high energy propellants containing RDX

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Defence Technology（防务技术） 2022年第4期18卷 557-566页

作者： En-fa Fu Na Sun zheng-gang xiao Key Laboratory of Special Energy Materials Ministry of Education School of Chemical Engineering Nanjing University of Science and Technology

A kind of phase change material(PCM)-based nanocomposite was prepared and added into high energy propellants containing RDX as additives to investigate its effect on thermal decomposition and burning characteristic of high energy *** effect of PCM-based nanocomposites on thermal decomposition of high energy propellants is investigated by TG/DSC-FTIR-MS *** to the delayed protection effect(PCM-based nanocomposites can absorb lots of heat at the range of certain temperature when it undergoes structure change or phase transitions)of PCM-based nanocomposites under the thermal decomposition condition,the thermal stability of high energy propellants modified with PCMbased nanocomposites is *** the same time,the concentration of N2,NO2,H2O and CO_(2)is increased during thermal decomposition of high energy propellants whereas NO and CO is *** burning gaseous products and burning characteristic of high energy propellants are studied by the combination of closed bomb test and Fourier transform infrared *** main burning gaseous products are N2,CO_(2),CO,H2O,CH4,*** the high energy propellant modified with PCM-based nanocomposites,the concentration of CH4is increased while CO,CO_(2) and H2O is decreased under the high-pressure burning *** progressivity factor of high energy propellants is increased by22.2%compared with the control sample while the maximum pressure is merely decreased 1.25%after the addition of the PCM-based nanocomposite,thus PCM-based nanocomposites can be used to adjust the burning process and improve the burning progressivity of high energy *** study is expected to boost the practical application of PCM-based nanocomposite to the propellant formulation and effectively control the burning characteristic of high energy propellants.

关键词： Phase change material Propellants Nanocomposite Thermal decomposition Burning

Joint Sample Position Based Noise Filtering and Mean Shift Clustering for Imbalanced Classification Learning

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Tsinghua Science and Technology 2024年第1期29卷 216-231页

作者： Lilong Duan Wei Xue Jun Huang xiao zheng School of Computer Science and Technology Anhui University of TechnologyMaanshan 243032China Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China

The problem of imbalanced data classification learning has received much *** classification algorithms are susceptible to data skew to favor majority samples and ignore minority *** weighted minority oversampling technique(MWMOTE)is an effective approach to solve this problem,however,it may suffer from the shortcomings of inadequate noise filtering and synthesizing the same samples as the original minority *** this end,we propose an improved MWMOTE method named joint sample position based noise filtering and mean shift clustering(SPMSC)to solve these ***,in order to effectively eliminate the effect of noisy samples,SPMsC uses a new noise filtering mechanism to determine whether a minority sample is noisy or not based on its position and distribution relative to the majority *** that MWMOTE may generate duplicate samples,we then employ the mean shift algorithm to cluster minority samples to reduce synthetic replicate ***,data cleaning is performed on the processed data to further eliminate class *** on extensive benchmark datasets demonstrate the effectiveness of SPMsC compared with other sampling methods.

关键词： imbalanced data classification oversampling noise filtering clustering

The Influence of Water Level Change in Slope Stability of Earth Dam

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上海交通大学学报 2004年第z2期38卷 217-222页

作者： xiao zheng-hua Han Bo Liao Hong-jian Gao xiao-yu Department of Civil Engineering Xi''an Jiaotong University Xi''an710049 China College of Architectural Engineering Xinjiang University Urumqi830008 China Department of Civil Engineering Xi''an Jiaotong University Xi''an710049 China Department of Civil Engineering Xi''an Jiaotong University Xi''an710049 China Department of Civil Engineering Xi''an Jiaotong University Xi''an710049 China

The analysis of seepage flow and slope stability to earth dam in water level change is performed. FEM is used to analyzing the influence of percolation and the results including the pore water head of any point, seepage discharge and so on are obtained. The method of slices is introduced to calculating the slope stability of the earth dam. Through an example it is separately discussed the influence of seepage flow when water level is changed in earth dam slope and the effects of percolation in the stability of the earth dam slope. Some helpful conclusions are *** can be making the best of the tow methods and the results can be used in engineering for reference.

关键词： seepage flow stability factor FEM the method of Bishop

The Invariance Principle for p-■Chain

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Acta Mathematica Sinica,English Series 2007年第1期23卷 41-56页

作者： Di He HU zheng Yan xiao School of Mathematics and Statistics Wuhan University Wuhan 430072 P. R. China School of Statistics Renmin University of China Beijing 100872 P. R. China

There are two parts in this paper. In the first part we construct the Markov chain in random environment（MCRE）, the skew product Markov chain and p-θ^→ chain from a random transition matrix and a two-dimensional probability distribution, and in the second part we prove that the invarianee principle for p-θ^→ chain, a more complex non-homogeneous Markov chain, is true under some reasonable conditions. This result is more powerful.

关键词： random transition matrix Markov chain in random environment skew product Markov chain p-θ^→ chain invariance principle

Unusual phase behavior of decane-dodecane mixtures confined in SBA-15:Size effect on binary phase diagram

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Chinese Chemical Letters 2012年第10期23卷 1173-1176页

作者： Hai Rong Pei xiao Yan xiao zheng Lan College of Chemistry and Materials Science Shandong Agriculture UniversityTaian 271018China

Phase behavior of normal decane-dodecane （n-CloH2/-CI2H26, Clo-C12） system confined in SBA-15 （Santa Barbara Amorphous, pore diameters 3.8, 7.8, and 17.2 nm） has been studied by using differential scanning calorimetry. It has been found solid-liquid phase diagram of the C10-C12/SBA-15 system is composed of a straight line （3.8 nm）, a curve （7.8 nm） and a loop line （17.2 nm）. The growth of the phase diagram clearly shows the size effect on phase behavior of binary alkanes. Phase behavior has been compared among the systems C10H22-CI2H26]SBA-15, C12H26-C14H3o/SBA-15 and C14H30-C16H34/SBA-15.

关键词： Phase behavior Confinement SBA-15 Decane–dodecane system