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Luminescence properties of nitrogen-rich Ca-SiAlON:Eu2+ phosphors prepared by freeze-drying assisted combustion synthesis

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 687-692页

作者： Zhang-lin Chen Kai Liu Xuan-yi Yuan ke-xin Chen Beijing key Laboratory of Optoelectronic Functional Materials&Micro-nano Devices Department of PhysicsRenmin University of ChinaBeijing 100872China State key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100872China

Nitrogen-rich Eu2+-doped Ca-α-SiAlON phosphors(Cam/2-xSi12-m-nAlm+nOnN16-n:xEu) were synthesized by a freeze-drying assisted combustion synthesis(CS) route. Fast-synthesized products with high purity and uniform particle morphology were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The analysis of lattice parameters by comparison with empirical equations showed that the as-prepared phosphors had low oxygen content. A series of samples were prepared according to the stoichiometry of Cam/2-0.08Si12-mAlmN16:0.08 Eu for further research. The influences of m value on the luminescence properties were investigated in detail. As m increased, a redshift phenomenon was observed in both the excitation and emission spectra. First-principle electronic structure calculations showed that the 3d energy level of Ca played an important role in the occurrence of the redshift phenomenon.

关键词： freeze-drying combustion synthesis phosphors powder fluorescence spectra first-principle calculation

Tuning heat transport via coherent structure manipulation:recent advances in thermal turbulence

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National Science Review 2023年第6期10卷 245-257页

作者： ke-Qing Xia Shi-Di Huang yi-Chao Xie Lu Zhang Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering Southern University of Science and Technology State key Laboratory for Strength and Vibration of Mechanical Structures and School of Aerospace Xi'an Jiaotong University

Tuning transport properties through the manipulation of elementary structures has achieved great success in many areas,such as condensed matter ***,the ability to manipulate coherent structures in turbulent flows is much less *** article reviews a recently discovered mechanism of tuning turbulent heat transport via coherent structure *** first show how this me chanism can be realized by applying simple geometrical confinement to a classical thermally driven turbulence, which leads to the condensation of elementary coherent structures and significant heat-transport enhancement,despite the resultant slower *** potential applications of this new paradigm in passive heat management are also *** then explain how the heat transport behaviors in seemingly different turbulence systems can be understood by this unified framework of coherent structure *** future directions in this research area are also outlined.

关键词： coherent structure turbulent flow heat transport geometrical confinement dynamical constraint

Numerical simulation of flow characteristics of side-bottom combined blowing in iron bath reactor

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Journal of Iron and Steel Research International 2023年第2期30卷 236-248页

作者： yi-bo He Wen-ke Guo yi-hong Li Guang-ming Liu Xin Cui School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024ShanxiChina

A numerical model of an iron bath smelting reduction furnace with side-bottom combined blowing was established to study the influence of blowing arrangements on the stirring effect of the molten pool,and the accuracy of numerical simulation was verified by water model *** comparing the flow field of molten pool with single nozzle,double nozzles(symmetrical and asymmetrical),and four nozzles(symmetrical and asymmetrical),the proportion of dead zone,average turbulent kinetic energy,and mixing time,the results show that asymmetrical bottom blowing is better than symmetrical bottom blowing,and the effect of double nozzles bottom blowing was better than that of four nozzles bottom *** mixing effect is the worst under the condition of single *** the bottom blowing is asymmetrical with double nozzles,the mixing time is the *** the condition of double nozzles asymmetrical bottom blowing,when the insertion angle and depth of side lance are larger and deeper,the velocity streamline of molten slag layer is denser and the value is larger;meanwhile,the reflux of molten iron layer is larger,the proportion of dead zone is smaller,and the whole molten pool is fully *** the insertion depth of the side lance is deeper,the gas holdup in the molten pool is greater and the stirring of the molten pool is more intense,while the insertion angle has little effect on the gas *** comparing the influence of different side blowing conditions on the slag layer,it is found that the slag layer is divided into two layers by double-layer side lance,with the critical surface of the slag layer at about 200-260 mm from the bottom,and the insertion depth of the lower side lance has a greater influence on the layering of the slag.

关键词： Iron bath smelting reduction Side-bottom combined blowing Numerical simulation Mixing time Slag layering

Effect of Rare Earth and Cooling Process on Microstructure and Mechanical Properties of an Ultra-Cleaned X80 Pipeline Steel

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 639-648页

作者： He Duan yi-yin Shan ke Yang Xian-Bo Shi Wei Yan yi Ren Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China State key Laboratory of Metal Materials and Application for Marine Equipment Anshan114009China

In order to explore the eff ect of a small amount of rare earth addition in ultra-cleaned pipeline steel and the influence of the cooling process on the tensile and impact properties,three API X80 pipeline steels were fabricated by varying RE addition and the cooling process at the same *** microstructures with different features for a low C high Nb microalloyed high-strength pipeline steel and the corresponding mechanical properties were *** results showed that even in the ultra-cleaned steel with O and S contents less than 10 ppm,the addition of RE would still cause an increase in the volume fraction of inclusions consisting of complicated RE oxysulfide and RE *** inclusions formed in the 112 ppm RE steel were harmful to the low temperature toughness,while few inclusions formed in the 47 ppm RE steel had almost no influence on the low temperature *** two RE additions had no effect on strength of the *** the finishing cooling temperature was increased and the cooling rate was decreased within a certain range,the volume fractions of polygonal ferrite and quasi-polygonal ferrite as well as the number density and size of martensite–austenite islands were *** such combined effect,the strength of the steels had almost no *** the finishing cooling temperature was increased from 481 to 584℃and the cooling rate was reduced from 20 to 13℃/s,for the steel with 112 ppm addition of RE,there was an obvious decrease in the low temperature *** reduced value(about 33 J)of the USE of steel consisted of two parts including the influence(about 18 J)of more inclusions formed due to 112 ppm addition of RE and the eff ect(about 15 J)of the lower high-angle grain boundaries.

关键词： Low temperature toughness Cooling process High-angle grain boundaries(HAGBs) Ductile–brittle transition temperature(DBTT) Rare earth Inclusions

Effective Variational Data Assimilation in Air-Pollution Prediction

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Big Data Mining and Analytics 2018年第4期1卷 297-307页

作者： Rossella Arcucci Christopher Pain yi-ke Guo Data Science Institute Department of ComputingImperial College LondonLondonSW72AZUnited Kingdom Department of Earth Science&Engineering Imperial College LondonLondonSW72AZUnited Kingdom

Numerical simulations are widely used as a predictive tool to better understand complex air flows and pollution transport on the scale of individual buildings,city blocks,and entire *** improve prediction for air flows and pollution transport,we propose a Variational Data Assimilation(VarDA)model which assimilates data from sensors into the open-source,finite-element,fluid dynamics model *** is based on the minimization of a function which estimates the discrepancy between numerical results and observations assuming that the two sources of information,forecast and observations,have errors that are adequately described by error covariance *** conditioning of the numerical problem is dominated by the condition number of the background error covariance matrix which is *** this paper,a preconditioned VarDA model is presented,it is based on a reduced background error covariance *** Empirical Orthogonal Functions(EOFs)method is used to alleviate the computational cost and reduce the space *** results are provided assuming observed values provided by sensors from positions mainly located on roofs of buildings.

关键词： data assimilation reduced order space big data preconditioning

A quantum switching architecture on the basis of limited nonlocal operation

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The Journal of China Universities of Posts and Telecommunications 2006年第4期13卷 91-94页

作者： JIANG Min ZHANG Zeng-ke DONG Dao-yi Department of Automation Tsinghua University Beijing 100084 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

Quantum information system is fragile to be disturbed by the external environment. Quantum switching architecture is one of the promising schemes for transferring input quantum data to its destination port substituted for fully connected quantum networks. Since at present, interactions between the qubits are limited to a small number of neighboring qubits, one novel approach was extended, and the improved architecture was further demonstrated under limited nonlocal operation. The performance evaluation shows that the whole architecture with improved control module can achieve a time complexity of O（n^2） and will be more feasible for physical realization.

关键词： quantum information quantum switching time optimization limited operation

The Northern Path of Asian Dust Transport from the Gobi Desert to North America

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Atmospheric and Oceanic Science Letters 2010年第3期3卷 155-159页

作者： Chen ke-yi The Department of Atmospheric Sciences Chengdu University of Information & Technology Chengdu 610225 China

The aerosol index (AI) of the Total Ozone Mapping Spectrometer (TOMS) satellite data (1979 2001) was analyzed to reveal the climatological long-distance path of dust transport from Asia to North America. The AI in the west coast of the United States is highly correlated with that in the Gobi desert. Additionally, from the TOMS satellite images, it can be seen that very strong plumes advect from Asia to the west coast of North America in typical dust storm cases. When applying the sourcereceptor relationship to detect the northern dust transport path between the Gobi source region and the west coast of the United States receptor region, it is evident that the dust plume can be transported northward beyond 60°N from its source region and that it takes 5 to 6 days to reach the west coast of the United States. The cross correlation technique shown in this work is a useful tool that can be applied in other regions to give useful insights into relationships between major dust sources and downwind receptor locations by using remotely sensed dust observations.

关键词： dust transport the Total Ozone Mapping Spectrometer satellite data

Long-term kinematics and mechanism of a deep-seated slow-moving debris slide near Wudongde hydropower station in Southwest China

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Journal of Mountain Science 2018年第2期15卷 364-379页

作者： JIANG Shu WANG yi-feng TANG Chuan LIU ke Postdoctoral Research Station China Three Gorges Corporation Beijing 100038 China Wudongde Project Construction Department China Three Gorges Projects Development Co. Ltd Luquan 651500 China State key Laboratory of C-eohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610059 China

Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide located on the Jinsha river bank in southwest China. This debris slide is known to have a volume of 27×106 ms in active state for at least one century. Field survey and geotechnical investigation were carried out to define the structure of the landslide. The physical and mechanical properties of the landslide materials were obtained by in-situ and laboratory tests. Additionally, surface and subsurface displacements, as well as groundwater level fluctuations, were monitored since 2005. Movement features, especially the response of the landslide movement to rainfall, were analysed. Relationships between resisting forces and driving forces were analysed by using the limit equilibrium method assuming rigid-plastic frictional slip. The results confirmed a viscous comoonent in the long-term continuous movement resulting in the quasioverconsolidated state of the slip zone with higher strength parameters than some other types of slowmoving landslides. Both surface and subsurface displacements showed an advancing pattern by the straight outwardly inclined （rather than gently or reversely inclined） slip zone, which resulted in low resistance to the entire sliding mass. The average surface displacement rate from 2005 to 2016 was estimated to be 0.19-0.87 mm/d. Basal sliding on the silty clay seam accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the kinematics of Jinpingzi landslide while the role of groundwater level, though positive, was not significant. The response of the groundwater level to rainfall infiltration was not apparent. Unlike some shallow slow-moving earth flows or mudslides, whose behaviors are directly related to the phreatic groundwater level, th

关键词： Kinematics Slow-moving debris slide Shear strength Rainfall infiltration Viscouscomponent

Large Deviation Principle for the Fourth-order Stochastic Heat Equations with Fractional Noises

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Acta Mathematica Sinica,English Series 2010年第1期26卷 89-106页

作者： yi Ming JIANG ke Hua SHI Yong Jin WANG School of Mathematical Sciences and LPMC Nankai University Tianjin 300071 P. R. China

In this paper, we shall study a fourth-order stochastic heat equation driven by a fractional noise, which is fractional in time and white in space. We will discuss the existence and uniqueness of the solution to the equation. Furthermore, the regularity of the solution will be obtained. On the other hand, the large deviation principle for the equation with a small perturbation will be established through developing a classical method.

关键词： fourth-order stochastic heat equation fractional noise existence and uniqueness regularity large deviation principle