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In-situ generation of gold nanoparticles on MnO_2 nanosheets for the enhanced oxidative degradation of basic dye(Methylene Blue)

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Journal of Environmental Sciences 2018年第3期30卷 236-245页

作者： Xueqin bao Zhen qin Tianshu Zhou Jingjing Deng School of Ecological and Environmental Sciences East China Normal University

In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective *** experiments were carried out to optimize the oxidation of basic dye（Methylene Blue（MB））,including the molar ratio of MnO2to chloroauric acid（HAu Cl4）,the p H of the solution and the effect of initial *** the optimal condition,the highest degradation efficiency for MB achieved to 98.9%within 60 min,which was obviously better than commercial MnO2powders（4.3%）and MnO2nanosheets（74.2%）.The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO2nanosheets and Au-NPs and facilitated the uptake of electrons by MnO2from MB during the oxidation,thus validating the application of MnO2/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.

关键词： MnO2/Au-NPs nanocomposite In-situ generation Dye degradation Synergistic effect and inteffacial effect Enhanced oxidative degradation

An improved Bag-of-Words framework for remote sensing image retrieval in large-scale image databases

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International Journal of Digital Earth 2015年第4期8卷 273-292页

作者： Jin Yang Jianbo Liu qin dai Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences BeijingChina University of Chinese Academy of Sciences BeijingChina

Due to advances in satellite and sensor technology,the number and size of Remote Sensing(RS)images continue to grow at a rapid *** continuous stream of sensor data from satellites poses major challenges for the retrieval of relevant information from those satellite *** Bag-of-Words(BoW)framework is a leading image search approach and has been successfully applied in a broad range of computer vision problems and hence has received much attention from the RS ***,the recognition performance of a typical BoW framework becomes very poor when the framework is applied to application scenarios where the appearance and texture of images are very *** this paper,we propose a simple method to improve recognition performance of a typical BoW framework by representing images with local features extracted from base *** addition,we propose a similarity measure for RS images by counting the number of same words assigned to *** compare the performance of these methods with a typical BoW *** experiments show that the proposed method has better recognition performance than that of the BoW and requires less storage space for saving local invariant features.

关键词： remote sensing image retrieval base image Bag-of-Words visual word

Deterioration in Heat Transfer of Endothermal Hydrocarbon Fuel

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Journal of Thermal Science 2011年第2期20卷 173-180页

作者： Weixing Zhou Wen bao Jiang qin Yunfeng Qu Harbin Institute of Technology Harbin China 150001

Numerical studies under supercritical pressure are carried out to study the heat transfer characteristics in a single-root coolant channel of the active regenerative cooling system of the scramjet engine, using actual physical properties of pentane. The relationships between wall temperature and inlet temperature, mass flow rate, wall heat flux, inlet pressure, as well as center stream temperature are obtained. The results suggest that the heat transfer deterioration occurs when the fuel temperature approaches the pseudo-critical temperature, and the wall temperature increases rapidly and heat transfer coefficient decreases sharply. The decrease of wall heat flux, as well as the increase of mass flow rate and inlet pressure makes the starting point of the heat transfer deterioration and the peak point of the wall temperature move backward. The wall temperature increment induced by heat transfer deterioration decreases, which could reduce the severity of the heat transfer deterioration. The relational expression of the heat transfer deterioration critical heat flux derives from the relationship of the mass flow rate and the inlet pressure.

关键词： supercritical pressure pentane heat transfer deterioration numerical study

Dynamic Characteristics of Hydrocarbon Fuel within the Channel at Supercrit- ical and Pyrolysis Condition

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Journal of Thermal Science 2017年第6期26卷 560-569页

作者： YU Bin ZHOU Weixing qin Jiang bao Wen Harbin Institute of Technology 150001 Heilongjiang China

Regenerative cooling with fuel as the coolant is used in the scramjet engine. In order to grasp the dynamic cha- racteristics of engine fuel supply processes, this article studies the dynamic characteristics of hydrocarbon fuel within the channel. A one-dimensional dynamic model was proved, the thermal energy storage effect, fuel volume effect and chemical dynamic effect have been considered in the model, the ordinary differential equations were solved using a 4th order Rungc-Kutta method. The precision of the model was validated by three groups of expe- rimental data. The effects of input signal, working condition, tube size on the dynamic characteristics of pressure, flow rate, temperature have been simulated. It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow. The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the control performance of the engine thrust system. Meanwhile, when the inlet flow rate appears the step change, the inlet pressure leads to overshoot, the overshoot can reach as much as 100%, such highly transient impulse will result in detrimental effect on fucl pump.

关键词： dynamic characteristics n-Decane supercritical pyrolysis

Cross-correlation matrix Root-MUSIC algorithm for bistatic multiple-input multiple-output radar

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Science China(Information Sciences) 2015年第2期58卷 58-67页

作者： qin GuoDong bao Dan LIU GaoGao LI Peng The Ministry Key Laboratory of Electronic Information Countermeasure and Simulation Xidian University

A novel Root-MUSIC algorithm based on cross-correlation matrix is proposed to estimate the direction of arrival(DOA) and direction of departure(DOD) for the bistatic multiple-input multiple-output(MIMO)radar. In the algorithm, the cross-correlation matrix is first constructed by using the received data which are arranged according to the transmit array and the receive array, respectively. And the DOAs and DODs are estimated independently employing cross-correlation Root-MUSIC algorithms without eigendecomposition,where the null spaces are constructed with a linear operation of the cross-correlation matrices. Secondly the pair-matching of DOAs and DODs is accomplished by solving an angle estimate optimization. The effectiveness of the proposed method is verified through numerical simulations, and it is shown that the proposed method can provide more accurate angle estimation with small computational complexity than conventional eigendecomposition algorithms.

关键词： bistatic MIMO radar DOD DOA cross-correlation Matrix angle estimation

Covalent electron density analysis and surface energy calculation of gold with the empirical electron surface model

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 676-682页

作者： bao-qin Fu Zhi-lin Li Wei Liu College of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China Laboratory of Advanced Materials Department of Material Science and Engineering Tsinghua University Beijing 100084 China

Based on the empirical electron surface model （EESM）,the covalent electron density of dangling bonds （CEDDB） was calculated for various crystal planes of gold,and the surface energy was calculated *** results show that CEDDB has a great influence on the surface energy of various index surfaces and the anisotropy of the *** calculated surface energy is in agreement with experimental and other theoretical *** calculated surface energy of the close-packed （111） surface has the lowest surface energy,which agrees with the theoretical ***,it is found that the spatial distribution of covalent bonds has a great influence on the surface energy of various index ***,CEDDB should be a suitable parameter to describe and quantify the dangling bonds and surface energy of various crystal surfaces.

关键词： surface energy dangling bonds covalent bonds electron density gold

Experimental Study on Measurement and Calculation of Heat Flux in Supersonic Combustor of Scramjet

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Journal of Thermal Science 2015年第3期24卷 254-259页

作者： ZHANG Cong YAO Zhanli qin Jiang bao Wen Harbin Institute of Technology

An experimental measurement and calculation method which consist of thermal response model, convergence criteria and control algorithms, is proposed in this paper for the determination of heat flux in a scramjet combus- tot. Numerical simulations are done to evaluate the effectiveness of the proposed method, and experiments are made in the direct-connect hydrocarbon fueled scramjet combustor of Mach-6 flight for different equivalence ra- tios. The distribution of heat flux along the axial and circumferential directions can be obtained using the pro- posed method. The distribution of heat flux is uneven which is caused by the aerodynamic heating, combustion heat release and changes of section area, and the peak heat flux can be more than 2MW/m^2 during the experi- ments. Heat flux increases with the increase in equivalence ratio for the same Mach number. And axial distribu- tion of heat flux is uniform for different equivalence ratios. In addition, the combustion heat release area of the combustion chamber can therefore be concluded which is useful for guiding the structural design of the thermal protection system.

关键词： Scramjet Heat flux Thermal response model Thermal protection

Large eddy simulation for wind field analysis based on stabilized finite element method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第4期12卷 278-290页

作者： Cheng HUANG Yan bao dai ZHOU Jin-quan XU School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China

In this paper,a stabilized finite element technique,actualized by streamline upwind Petrov-Galerkin(SUPG) stabilized method and three-step finite element method(FEM),for large eddy simulation(LES) is developed to predict the wind flow with high Reynolds *** form of LES motion equation is combined with the SUPG stabilized term for the spatial finite element *** explicit three-step scheme is implemented for the temporal *** the numerical example of 2D wind flow over a square rib at Re=4.2×105,the Smagorinsky's subgrid-scale(SSGS) model,the DSGS model,and the DSGS model with Cabot near-wall model are applied,and their results are analyzed and compared with experimental ***,numerical examples of 3D wind flow around a surface-mounted cube with different Reynolds numbers are performed using DSGS model with Cabot near-wall model based on the present stabilized method to study the wind field and compared with experimental and numerical ***,vortex structures for wind flow around a surface-mounted cube are studied by present numerical *** and satisfactory results are obtained,which are consistent with most of the measurements even under coarse mesh.

关键词： Large eddy simulation(LES) Subgrid-scale model Stabilized finite element method(FEM) Unstructured grid Wind flow

Oxygen Isotopic Compositions in a Plagioclase-Olivine Inclusion from Ningqiang Similar to Those in Al-rich Chondrules

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Acta Geologica Sinica(English Edition) 2021年第5期95卷 1583-1590页

作者： dai Deqiu bao Haimei LIU Shuang YIN Feng Department of Geology Hunan University of Science and TechnologyXiangtanHunan 411201China Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081China Hunan Provincial Key Laboratory of Shale Gas Resource Utilization Hunan University of Science and TechnologyXiangtanHunan 411201China

We report the petrology and oxygen isotopic composition,using a Cameca Nano SIMS 50L ion microprobe,of a plagioclase-olivine inclusion,C#1,found in the Ningqiang carbonaceous *** addition to major phases(plagioclase,spinel and olivine),C#1 is also surrounded by a pyroxene rim(64 vol%Ca-rich and 36 vol%Ca-poor pyroxenes).On a three-isotope oxygen diagram,δ^(17)O vs.δ^(18)O,the compositions of individual minerals analyzed in C#1 fall along the carbonaceous chondrite anhydrous mineral line(CCAM),and oxygen isotopic compositions in C#1 show significant variability in δ^(18)O and δ^(17)*** oxygen isotopic compositions of the pyroxene rim minerals are similar to those of the other host minerals,which suggests that the rim likely formed from the same melting process as the *** rim is considered to have formed as a result of interaction between an ^(16)O-poor gas and a *** spinel grains are typically ^(16)O-rich and likely of relict origin,which is similar to ^(16)O-rich Ca-,Al-rich inclusions,which are probably a precursor of C#*** inclusion then likely melted in an ^(16)O-poor region where chondrules form,accompanied by oxygen isotope exchange with an ^(16)O-poor *** anorthite,pyroxene and spinel might have undergone fluid-assisted thermal metamorphism on the Ningqiang chondrite parent *** oxygen isotope data and evolution of the C#1 plagioclase-olivine inclusion are similar with those of Al-chondrules in chondrites.

关键词： meteorite petrology oxygen isotopes CAIs plagioclase–olivine inclusion Al-rich chondrules Ningqiang chondrite Shanxi