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An improvement of Chen-Ru-Yan's degenerated second main theorem

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Science China Mathematics 2015年第12期58卷 2517-2530页

作者： shi lei RU Min Department of Mathematics East China Normal University Department of Mathematics University of Houston

We give an improvement for the second main theorem of algebraically non-degenerate holomorphic curves into a complex projective variety V intersecting hypersurfaces in subgeneral position, obtained by Chen et al.(2012... 详细信息

关键词： Nevanlinna theory holomorphic curve second main theorem truncation level

Sulphate attack resistance of high-performance concrete under compressive loading

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第7期14卷 459-468页

作者： Hui XU Yu-xi ZHAO lei CUI bi XU Institute of Structural Engineering Zhejiang University School of Civil Engineering Newcastle University CCCC Tianjin Dredging Co. Ltd.

In this paper, an experimental study on the sulphate attack resistance of high-performance concrete (HPC) with two different water-to-binder ratios (w/b) under compressive loading is presented. The sulphate concentration, compressive strength, and the mass change in the HPC specimens were determined for immersion in a Na2SO4 solution over different durations under external compressive loading by self-regulating loading equipment. The effects of the compressive stress, the w/b ratio, and the Na2SO4 solution concentration on the HPC sulphate attack resistance under compressive loading were analysed. The results showed that the HPC sulphate attack resistance under compressive loading was closely related to the stress level, the w/b ratio, and the Na2SO4 solution concentration. Applying a 0.3 stress ratio for the compressive loading or reducing the w/b ratio clearly improved the HPC sulphate attack resistance, whereas applying a 0.6 stress ratio for the compressive loading or exposing the HPC to a more concentrated Na2SO4 solution accelerated the sulphate attack and HPC deterioration.

关键词： Sulphate attack resistance High-performance concrete (HPC) Compressive loading

An evaluation of new satellite-derived latent and sensible heat fluxes with moored buoy data, OAFlux and NCEP2 reanalysis products

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Acta Oceanologica Sinica 2017年第9期36卷 27-38页

作者： ZHANG lei shi Hanqing Institute of Meteorology and Oceanography National University of Defense Technology Nanjing 211101 China

New satellite-derived latent and sensible heat fluxes are performed by using Wind Sat wind speed, Wind Sat sea surface temperature, the European Centre for Medium-range Weather Forecasting（ECMWF） air humidity, and ECMWF air temperature from 2004 to 2014. The 55 moored buoys are used to validate them by using the 30 min and 25 km collocation window. Furthermore, the objectively analyzed air-sea heat fluxes（OAFlux） products and the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis 2（NCEP2） products are also used for global comparisons. The mean biases of sensible and latent heat fluxes between Wind Sat flux results and buoy flux data are –0.39 and –8.09 W/m^2, respectively. In addition, the rootmean-square（RMS） errors of the sensible and latent heat fluxes between them are 5.53 and 24.69 W/m^2,respectively. The RMS errors of sensible and latent heat fluxes are observed to gradually increase with an increasing buoy wind speed. The difference shows different characteristics with an increasing sea surface temperature, air humidity, and air temperature. The zonal average latent fluxes have some high regions which are mainly located in the trade wind zones where strong winds carry dry air in January, and the maximum value centers are found in the eastern waters of Japan and on the US east coast. Overall, the seasonal variability is pronounced in the Indian Ocean, the Pacific Ocean, and the Atlantic Ocean. The three sensible and latent heat fluxes have similar latitudinal dependencies; however, some differences are found in some local regions.

关键词： latent and sensible heat fluxes WindSat ECMWF reanalysis data OAFlux

Application of a Neural Network to Store and Compute the Optical Properties of Non-Spherical Particles

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Advances in Atmospheric Sciences 2022年第12期39卷 2024-2039页

作者： Jinhe YU lei bi Wei HAN Xiaoye ZHANG Key Laboratory of Geoscience big Data and Deep Resource of Zhejiang Province School of Earth SciencesZhejiang UniversityHangzhou 310027China Center for Earth System Modeling and Prediction China Meteorological AdministrationBeijing 100081China Numerical Weather Prediction Center China Meteorological AdministrationBeijing 100081China Key Laboratory of Atmospheric Chemistry of China Meteorological Administration Institute of Atmospheric CompositionChinese Academy of Meteorological SciencesBeijing 100081China

Radiative transfer simulations and remote sensing studies fundamentally require accurate and efficient computation of the optical properties of non-spherical *** paper proposes a deep learning(DL)scheme in conjunction with an optical property database to achieve this *** neural network(DNN)architectures were obtained from a dataset of the optical properties of super-spheroids with extensive shape parameters,size parameters,and refractive *** dataset was computed through the invariant imbedding T-matrix *** separate DNN architectures were created to compute the extinction efficiency factor,single-scattering albedo,asymmetry factor,and phase *** criterion for designing these neural networks was the achievement of the highest prediction accuracy with minimal DNN *** numerical results demonstrate that the determination coefficients are greater than 0.999 between the prediction values from the neural networks and the truth values from the database,which indicates that the DNN can reproduce the optical properties in the dataset with high *** addition,the DNN model can robustly predict the optical properties of particles with high accuracy for shape parameters or refractive indices that are unavailable in the ***,the ratio of the database size(~127 GB)to that of the DNN parameters(~20 MB)is approximately 6810,implying that the DNN model can be treated as a highly compressed database that can be used as an alternative to the original database for real-time computing of the optical properties of non-spherical particles in radiative transfer and atmospheric models.

关键词： non-spherical particles light scattering super-spheroid model deep learning neural network

Amphibian and reptilian distribution patterns in the transitional zone between the Euro-Siberian and Central Asia Subrealms

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Journal of Arid Land 2015年第4期7卷 555-565页

作者： ZHOU Lu shi lei College of Animal Science Xinjiang Agricultural University

There exist some controversies over the larger zoogeographic divisions of the arid areas of Central Asia, whose characteristics include complex ecological environments, complex fauna origins and unique patterns of animal distribution. The aim of this study was to determine, using quantitative analysis, the distribution patterns of amphibians and reptiles in the arid areas of Central Asia, whose various physiographical regions were divided into 17 Operative Geographical Units （OGUs）. Based on the presence or absence of 52 amphibian and reptile genera in the 17 OGUs, and by making use of the Czekanowski Similarity Index, the Baroni-Urbani and Buser＇s Similarity Index, and the strong and weak boundary test, we studied the biotic boundaries within these contested regions. In accordance with our results, the classification dendrogram was divided into two main branches. One branch is composed of the northern OGUs of the Altai Mountains which are a part of the Euro-Siberian Subrealm. The other branch includes all of the OGUs south of the Altai Mountains, which belong to the Central Asia Subrealm. There is a significantly weak biotic boundary （DW〉0, GW〉GS, P〈0.01） between the Euro-Siberian Subrealm and the Central Asia Subrealm that corre- sponded to the transitional zones. The boundary between the two subrealms runs along the Altai Mountains, the Sayan Mountains, the Hangai Mountains and the Mongolian Dagurr Mountains. The boundaries between the main branches in the Central Asia Subrealm are weak, reflecting the widespread existence of transitional zones in the arid areas of Central Asia. The Tianshan Mountains should be elevated to form its own separate region, ＂the Middle Asian Mountain Region＂, which, due to its special fauna and environment, would be classified at the same level as the Mongolia-Xinjiang Region. With the approach of creating a cluster analysis dendogram based upon the genera of amphibians and reptiles, the relationship of these higher level zoogeographi

关键词： amphibian and reptile distribution pattern higher level zoogeographic division similarity analysis boundary test arid area Central Asia

PVC DISULFIDE AS CATHODE MATERIALS FOR SECONDARY LITHIUM BATTERIES

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Chinese Journal of Polymer Science 2006年第3期24卷 307-313页

作者： Guo-xiang Xu 其鲁 bi-tao Yu lei Wen Department of Applied Chemistry College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Department of lnorganic Nonmetal Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

PVC disulfide （2SPVC） was synthesized by solution crosslink and its molecular structure was confirmed by infrared spectrum. 2SPVC＇s specific area is 36.1 m^2·g^-1 tested by stand BET method, and granularity experiment gives out the particle size of d0.5 = 11.3 μm. With SEM （Scanning Electron Microscope） experiment the surface morphology and particle shape of 2SPVC were observed. Cyclic voltammetry （scan rate： 0.5 mV · s^-1） shows that 2SPVC experience an obvious S-S redox reaction in charge-discharge process. When 2SPVC was used as cathode material for secondary lithium battery in a 1 mol·L^-1 solution of lithium bis（trifluoromethylsulfonyl） imide （Li（CF3SO2）2N） in a 5：45：50 volume ratio mixture of o-xylene （oxy）, diglyme （DG） and dimethoxymethane （DME） at 30℃, the first discharge capacity of 2SPVC is about 400.3 mAh·g^-1 which is very close to its theoretical value （410.5 mAh ·g^-1） at a constant discharge current of 15 mA·g^-1. It can retain at about 346.1 mAh ·g^-1 of discharge capacity after 30 charge-discharge cycles. So 2SPVC is a very promising cathode candidate for rechargeable lithium batteries.

关键词： PVC disulfide (2SPVC) Cathode Lithium battery Capacity Cycle.

Energy budget of cold and hot gas-solid fluidized beds through CFD-DEM simulations

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Particuology 2024年第6期89卷 153-171页

作者： lei bi Yunpeng Jiao Chunjiang Liu Jianhua Chen Wei Ge School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization ***,the energy paths are proposed from thermodynamic *** consumption means total power input to the specific system,and it can be decomposed into energy retention and energy *** retention is the variation of accumulated mechanical energy in the system,and energy dissipation is the energy converted to heat by irreversible *** based on the Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)framework,different energy terms are quantified from the specific flow elements of fluid cells and particles as well as their interactions with the *** order to clarify the energy budget,it is important to identify which system is studied:the particle-fluid system or the particle *** the cold flow,the total energy consumption of the particle sub-system can well indicate the onset of bubbling and turbulent,while the variation of local energy consumption terms can reflect the evolution of heterogeneous *** the hot flow,different heat transfer mechanisms are analyzed and the solver is modified to reproduce the experimental *** impact of the heat transfer mechanisms and heat production on energy consumption is also *** proposed budget method has proven to be energy-conservative and easy to conduct,and it is hopeful to be applied to other multiphase flow systems.

关键词： Energy budget Gas-solid fluidization CFD-DEM Regime transition Heat transfer mechanism

Effect of Squealer Tip with Deep Scale Depth on the Aero-thermodynamic Characteristics of Tip Leakage Flow

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Journal of Thermal Science 2022年第5期31卷 1773-1789页

作者： bi Shuai WANG Longfei WANG Feilong WANG lei LI Ziqiang Jiangsu Province Key Laboratory of Aerospace Power System Nanjing University of Aeronautics and AstronauticsNanjing210016China

In this paper,the aero-thermal performance of squealer tips with deep-scale depth is numerically investigated in an axial flow turbine,which is compared with the squealer tip with traditional cavity *** methods were validated with experimental *** effect of cavity depth and tip clearance was *** numerical results show that for the squealer tip with conventional cavity depth,the size of the reflux vortex enlarges as the cavity depth *** velocity and uniformity of high entropy production rate(EPR)inside the cavity reduce obviously with the cavity developing into ***,the increase of depth 10%of the blade span(H)leads to enlargement of cavity volume,which increases the total entropy production *** the overall dimensionless entropy production rate(DEPR)of gap and cavity obtains a maximum increase of 43.54%in contrast to the case with 1%H depth *** a result,the relative leakage mass flow rate reduces by 20.6%as the cavity depth increases from 1%to 10%.Given the heat transfer,as the cavity significantly increases to 10%H,the enhanced cavity volume results in a more enormous cavity vortex with low velocity covering the floor,which weakens the convective heat transfer intensity and reduces the area of high heat *** normalized average heat transfer coefficient at the cavity bottom reduces by 40.26%compared to the cavity depth of 1%*** addition,the deep-scale cavity is more effective in inhibiting leakage flow at smaller tip *** reduction amplitude of normalized average heat transfer coefficient at the squealer floor decreases as tip clearance increases,which reduces at most by about 72.6%for the tip clearance of 1%H.

关键词： squealer tip turbine aerothermodynamics tip leakage flow deep-scale depth heat transfer numerical methods

Quantum transport in topological semimetals under magnetic fields (III)

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Frontiers of physics 2023年第2期18卷 63-87页

作者： lei shi Hai-Zhou Lu Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and TechnologyShenzhen 518055China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen 518055China

We review our most recent research on quantum transport,organizing the review according to the intensity of the magnetic field and focus mostly on topological semimetals and topological *** first describe the phenomenon of quantum transport when a magnetic field is not *** introduce the nonlinear Hall effect and its theoretical ***,we discuss Coulomb instabilities in 3D higher-order topological ***,we pay close attention to the surface states and find a function to identify the axion insulator in the antiferromagnetic topological insulator *** weak magnetic fields,we focus on the decaying Majorana oscillations which has the correlation with spin−orbit *** the section on strong magnetic fields,we study the helical edge states and the one-sided hinge states of the Fermi-arc mechanism,which are relevant to the quantum Hall *** extremely large magnetic fields,we derive a theoretical explanation of the negative magnetoresistance without a chiral ***,we show how magnetic responses can be used to detect relativistic ***,we introduce the 3D quantum Hall effect’s charge-density wave mechanism and compare it with the theory of 3D transitions between metal and insulator driven by magnetic fields.

关键词： topological semimetal topological insulator axion insulator nonlinear Hall effect(NHE) quantum oscillation quantum Hall effect(QHE) charge density wave(CDW)