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Ferrimagnetic Properties of Bond Dilution Mixed Blume-Capel Model with Random Single-Ion Anisotropy

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Communications in Theoretical Physics 2005年第4X期44卷 743-748页

作者： LIU lei YAN shi-lei Department of Physics Suzhou University Suzhou 215006 China Jiangsu Key Loboratory of Thin Films Suzhou University Suzhou 215006 China CCAST (World Loboratory) P.O. Box 8730 Beijing 100080 China

We study the ferrimagnetic properties of spin 1/2 and spin-1 systems by means of the effective field theory. The system is considered in the framework of bond dilution mixed Blume-Capel mode/ （BCM） with random single-ion anisotropy. The investigation of phase diagrams and magnetization curves indicates the existence of induced magnetic ordering and single or multi-compensation points. Special emphasis is placed on the influence of bond dilution and random single-ion anisotropy on normal or induced magnetic ordering states and single or multi-compensation points. Normal magnetic ordering states take on new phase diagrams with increasing randomness （bond and anisotropy）, while anisotropy induced magnetic ordering states are always occurrence no matter whether concentration of anisotropy is large or small. Existence and disappearance of compensation points rely strongly on bond dilution and random singleion anisotropy. Some results have not been revealed in previous papers and predicted by Néel theory of ferrimagnetism.

关键词： ferrimagnetic property mixed Blume-Capel model induced magnetic ordering compensation point bond dilution and random single-ion anisotropy

Highly active mixed-phase TiO_2 photocatalysts fabricated at low temperature and the correlation between phase composition and photocatalytic activity

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Journal of Environmental Sciences 2008年第10期20卷 1263-1267页

作者： shi, lei WENG, Duan Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

The idea of varying volume ratio of water to ethanol in solvent was firstly employed to yield phase composition controllable mixed- phase titanium dioxide (TiO2) photocatalysts via a low temperature solvothermal route at 353 K. It was found that anatase contents increase from 0 to 100% with increase of ethanol contents in solvent. The mixed-phase TiO2 with 60% anatase content exhibited the best photocatalytic activity in photodecomposing formaldehyde (FAD) under UV light irradiation, which increases by abou...

关键词： titanium dioxide solvothermal synthesis phase compositional control synergistic effect photocatalysis

Time-Resolved Spectroscopy for the Study of Perovskite

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Chinese Journal of Electronics 2022年第6期31卷 1053-1071页

作者： SHEN Tangyao ZHAN Yiqiang shi lei Physics Department Fudan University School of Information Science and Technology Fudan University

Carrier behavior in halide perovskite is a critical factor impacting on the properties of material, and finally determines the performance of perovskite photovoltaic and luminescent devices. It is necessary to clarify the mechanism of carrier relaxation and migration at extremely microscopic time scale. Time-resolved spectroscopy provides a powerful means for the detection of ultrafast processes, which has been an indispensable technique in research on perovskites. In this review, we will elaborate the basic principle and system implementation of time-resolved spectroscopy, and introduce the applications for carrier dynamics in perovskite.

关键词： carrier relaxation critical factor extremely microscopic time scale carrier behavior halide perovskite perovskite photovoltaic devices time-resolved spectroscopy time resolved spectra luminescent devices photoluminescence high-speed optical techniques

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

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

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)

Role of a Single shield in Thermocouple Measurements in Hot Air Flow

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Journal of Thermal Science 2017年第6期26卷 523-532页

作者： ma hongwei shi lei tian yangtao National Key Laboratory of Science and Technology on Acre—Engines Collaborative Innovation Center of Advan ced Acre—Engine School of Energy&Power Engineering Beihang UniversityBeijing100191China

To investigate the role of a single shield on steady temperature measurement using therrnocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In order to compare with the experimental results, a cylindrical computational domain is established, which is the same size with the hot calibration wind-tannel. In the computational domain, two kinds of thermocouples, the bare-bead and the single-shielded thermocouples, are simulated respectively. Surface temperature distribution and the tempera- ture measurement bias of the two typical thermocouples are compared. The simulation results indicate that： 1） The existence of the shield reduces bead surface heat flux and changes the direction of wires inner heat conduction in a colder surrounding; 2） The existence of the shield reduces the temperature measurement bias both by improving bead surface temperature and by reducing surface temperature gradient; 3） The shield effectively reduces the effect of the ambient temperature on the temperature measurement bias; 4） The shield effectively reduces the influence of airflow velocity on the temperature measurement bias.

关键词： single-shield bare-bead thermocouples temperature measurement fluid-solid conjugated heat transfer.

A Survey of Macroscopic Brain Network Visualization Technology

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Chinese Journal of Electronics 2018年第5期27卷 889-899页

作者： CHEN Weifeng shi lei CHEN Wei School of Information Zhejiang University of Finance & Economics State Key Lab of Computer Science Institute of SoftwareChinese Academy of Sciences State Key Lab of CAD&CG Zhejiang University

Brain science, as an important branch of Neuroscience, is a discipline that studies the structure and function of brain nervous system of human and other mammals. With the invention of new technologies such as brain imaging, light microscopes and brain electromagnetics,brain science is gradually unraveling the mysteries of human emotion, intelligence and behavior. In this wave, data visualization punctuates the landmark advances in brain science since its beginning. This survey reviews the recent literature on brain network visualization(aka connectome)from the fields of both connectomics and visualization. In particular, we focus on the macroscopic-level brain network visualization techniques, that reveal the structural and functional connectivity of the whole brain, in comparison to microsopic-level neuronal connectivities. We also discuss the interactive visualization tools currently available for viewing the brain networks. Finally, we conclude with a number of ongoing challenges in macroscopic brain network visualization.

关键词： Brain network Connectomics Visualization

Critical Properties of Mixed Ising Spin System with Different Trimodal Transverse Fields in the Presence of Single-Ion Anisotropy

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Communications in Theoretical Physics 2006年第6期45卷 1131-1136页

作者： CHEN Qiang YAN shi-lei Department of Physics Suzhou University Suzhou 215006 China Jiangsu Key Laboratory of Thin Films Suzhou University Suzhou 215006 China Nantong shipping College Nantong 226006 China CCAST （World Loboratory） P.O. Box 8730 Beijing 100080 China

Within the framework of an effective field approximation, the effects of single-ion anisotropy and different trimodal transverse fields of two sublattices on the critical properties of the mixed spin-1/2 and spin-1 Ising system are investigated on the simple cubic lattice. A smaller single-lon anisotropy can magnify magnetic ordering phases and a larger one can depress magnetic ordering phase for T-Ω1/2 space at low temperatures, while a smaller single-ion anisotropy can hardly change the value of critical transverse field for T-Ω1 space. On the other hand, influences of two different trimodal transverse fields concentrations on tricritical points and magnetic ordering phases take on some interesting results in T-D space. The main reason comes from the common action of single-ion anisotropy, different transverse fields and two trimodal distributions.

关键词： critical property mixed spin system trimodal transverse field single-ion anisotropy