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Some basic principles for the linear theory of piezoelectric micropolar elastodynamics

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中国科学：物理学、力学、天文学英文版 2010年第6期53卷 1094-1100页

作者： luo En & LI WeiHua department of Applied Mechanics and engineering,sun yat-sen university,guangzhou 510275,china department of Applied Mechanics and engineering Sun Yat-sen University Guangzhou China

According to the basic idea of classical yin-yang complementarity and modern dual-complementarity,in a simple and unified way proposed by luo,some basic principles in the linear theory of piezoelectric micropolar elastodynamics can be established systematically. In this paper,an important integral relation in terms of convolutions is given,which can be considered as the generalized principle of virtual work in mechanics. Based on this relation,it is not only possible to obtain the principle of virtual work and the reciprocal theorem,but also to systematically derive the complementary functionals for the eleven-field,nine-field and six-field simplified Gurtin-type variational principles and the potential energy-functional for the three-field one in the linear theory of piezoelectric micropolar elastodynamics by the generalized Legendre transformations given in this paper. Furthermore,with this approach,the intrinsic relationships among various principles can be explained clearly.

关键词： piezoelectric micropolar elastodynamics principle of virtual work reciprocal theorem simplified Gurtin-type variational principle complementary relation

Linearly time-varying channel estimation and training power allocation for OFDM/MIMO systems using superimposed training

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Science china(Information Sciences) 2011年第7期54卷 1456-1470页

作者： ZHANG Han 1,DAI XianHua 2 & Pan DaRu 1 1 school of physics and Telecommunication engineering,South china Normal university,guangzhou 510006,china 2 department of Information Science and Technology,sun yat-sen university,guangzhou 510026,china school of physics and Telecommunication engineering South China Normal University department of Information Science and Technology SUN Yat-sen University

We address the problem of estimating the linearly time-varying (LTV) channel of orthogonal frequency division multiplexing (OFDM)/multiple-input multiple-output (MIMO) systems using superimposed training (ST).The LTV channel is modeled by truncated discrete Fourier *** on this model,a two-step approach is adopted to estimate the LTV channel over multiple OFDM *** also present performance analysis of the channel estimation and derive a closed-form expression for the channel estimation *** is shown that the estimation variances,unlike that of the conventional ST-based schemes,approach to a fixed lower-bound as the training length increases,which is directly proportional to information-pilot power *** wireless communication systems with a limited transmission power,we optimize the ST power allocation by maximizing the lower bound of the average channel *** results show that the proposed approach outperforms the frequency-division multiplexed training schemes.

关键词： OFDM/MIMO systems linearly time-varying channel estimation superimposed training training power allocation

Reflection of plane electromagnetic waves from the surface of a perfect conductor moving in an arbitrary direction

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Chinese Science Bulletin 2000年第17期45卷 1564-1569页

作者： HE Qicai & HUANG Yaoxiong1. department of physics, sun yat-sen university of Medical Sciences, guangzhou 510089, china 2. Institute of Biomedical engineering, Ji’nan university, guangzhou 510632, china Correspondence should be addressed to Huang Yaoxiong department of physics Sun Yat-sen University of Medical Sciences Guangzhou China Institute of Biomedical engineering Ji’nan University Guangzhou China

The reflection of plane electromagnetic waves (TE wave and TM wave) from a perfect conductor which moves in an arbitrary direction is investigated. Based on Maxwell’s equations and the boundary conditions for moving boundary, the relation between the field vectors of reflected and incident waves, and the reflection coefficient are derived. The energy balance between incident and reflected waves, the force exerted by electromagnetic waves to the moving conductor are also discussed and some new conclusions are suggested for notice.

关键词： plane electromagnetic wave moving conductor reflection coefficient radiation pressure.

Low-temperature Synthesis of Large-area Films of Molybdenum Trioxide Microbelts in Air and the Dependence of Their Field Emission Performance on Growth Conditions

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Journal of Materials Science & Technology 2010年第7期26卷 584-588页

作者： Dongmei Ban,Ningsheng Xu,Shaozhi Deng,Jun Chen and Juncong She State Key Lab of Optoelectronic Materials and Technologies,Guangdong Province Key Laboratory of Display Material and Technology,school of physics and engineering,sun yat-sen university,guangzhou 510275,china State Key Lab of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and Technology School of Physics and Engineering Sun Yat-sen University

A simple method is introduced for the preparation of large-area films of molybdenum trioxide （MoO3） microbelts. It is found that such films can be grown on indium tin oxide （ITO） glasses or silicon substrates at low temperatures by thermal evaporation deposition in air without using catalyst. Field emission measurements show that the turn-on field of the MoO3 microbelts is as low as 2.2 V/μm required to obtain a current density of 10 μA/cm^2, The combination of the simplicity of the growth method and the attractive field emission performance makes it a potential low-cost technique for the preparation of large-area field emission cold cathode material.

关键词： Field emission Large-area film Molybdenum trioxide Microstructures and synthesis

Stochastic resonance in the growth of a tumor induced bycorrelated noises

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Science Bulletin 2005年第20期 19-21页

作者： ZHONG Weirong, SHAO Yuanzhi & HE Zhenhui department of physics, sun yat-sen university, guangzhou 510275, china

Multiplicative noise is found to divide the growth law of tumors into two parts in a logistic model, which is driven by additive and multiplicative noises simul- taneously. The Fokker-Planck equation was also derived to explain the fact that the influence of the intensity of multi- plicative noise on the growth of tumor cells has a stochastic resonance-like characteristic. An appropriate intensity of multiplicative noise is benefit to the growth of the tumor cells. The correlation between two sorts of noises weakens the sto- chastic resonance-like characteristic. Homologous noises promote the growth of the tumor cells.

关键词： stochastic resonance multiplicative noise tumor logistic model correlation.

Bound states and critical behavior of the Yukawa potential

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Science china(physics,Mechanics & Astronomy) 2006年第1期49卷 60-71页

作者： LI Yongyao1,luo xiangqian1 & Helmut Krōger2 1. department of physics,sun yat-sen university,guangzhou 510275,china 2.Département de Physique,Université Laval,Québec G1K 7P4,Canada department of physics Sun Yat-sen University Guangzhou 510275 China

We investigate the bound states of the Yukawa potential V(r)=-λexp(-αr)/r, using different algorithms: solving the Schrodinger equation numerically and our Monte Carlo Hamiltonian approach. There is a critical α = αC, above which no bound state exists. We study the relation between αC and A for various angular momentum quantum number l. and find in atomic units, αC(l) = λ[A1 exp(-l/B1) + A2exp(-l/B2)], with A1 = 1.020(18), B1 = 0.443(14), A2 = 0.170(17), and B2 = 2.490(180).

关键词： Yukawa potential bound states critical behavior.

Vortex genesis over the Bay of Bengal in spring and its role in the onset of the Asian Summer Monsoon

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Science china Earth Sciences 2011年第1期54卷 1-9页

作者： WU GuoXiong1, GUAN Yue1,2, WANG TongMei3, LIU YiMin1, YAN JingHui4 & MAO JiangYu1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric physics, Chinese Academy of Sciences, Beijing 100029, china 2Graduate university of Chinese Academy of Sciences, Beijing 100049, china 3department of Atmospheric Science, sun yat-sen university, guangzhou 510275, china 4National Climate Center, china Meteorological Administration, Beijing 100080, china State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China department of Atmospheric Science Sun Yat-Sen University Guangzhou 510275 China National Climate Center China Meteorological Administration Beijing 100080 China

Physical processes associated with onset of the 1998 Asian summer monsoon were examined in detail using multi-source datasets. We demonstrated that strong ocean-atmosphere-land interaction in the northern Indian Ocean and tropical Asian area during spring is a fundamental factor that induces the genesis and development of a monsoon onset vortex over the Bay of Bengal (BOB), with the vortex in turn triggering onset of the Asian summer monsoon. In spring, strong surface sensible heating over India and the Indochina Peninsula is transferred to the atmosphere, forming prominent in situ cyclonic circulation, with anticyclonic circulations over the Arabian Sea and northern BOB where the ocean receives abundant solar radiation. The corresponding surface winds along the North Indian Ocean coastal areas cause the ocean to produce the in situ offshore currents and upwelling, resulting in sea surface temperature (SST) cooling. With precipitation on the Indochina Peninsula increasing from late April to early May, the offshore current disappears in the eastern BOB or develops into an onshore current, leading to SST increasing. A southwest-northeast oriented spring BOB warm pool with SST >31°C forms in a band from the southeastern Arabian Sea to the eastern BOB. In early May, the Somali cross-equatorial flow forms due to the meridional SST gradient between the two hemispheres, and surface sensible heat over the African land surface. The Somali flow overlaps in phase with the anticyclone over the northern Arabian Sea in the course of its inertial fluctuation along the equator. The convergent cold northerlies on the eastern side of the anticyclone cause the westerly in the inertial trough to increase rapidly, so that enhanced sensible heat is released from the sea surface into the atmosphere. The cyclonic vorticity forced by such sensible heating is superimposed on the inertial trough, leading to its further increase in vorticity strength. Since atmospheric inertial motion is destr

关键词： air-sea interaction spring BOB warm pool monsoon onset vortex inertial oscillation Asian summer monsoon onset

A primary study of the correlation between the net air-sea heat flux and the interannual variation of western North Pacific tropical cyclone track and intensity

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Acta Oceanologica Sinica 2011年第6期30卷 27-35页

作者： WU Liang WEN Zhiping HUANG Ronghui Center for Monsoon and Environment Research/department of Atmospheric Sciences Sun Yat-sen University Guangzhou 510275 China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

A singular value decomposition （SVD） analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones （WNPTCs） in the tropical cyclone （TC） active season （July–November） and the global net air-sea heat flux （Q net ） in the preceding season （April–June）. For this purpose, a tropical cyclone track and intensity function （TIF） is defined by a combination of accumulated cyclone energy （ACE） index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific （WNP） TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Q net anomalies in some key regions have a substantial remote impact on the WNP TC activity.

关键词： tropical cyclone western North Pacific the net air-sea heat flux (Q net ) interannual variation

Amplified circularly polarized luminescence of chiral metal-organic frameworks via post-synthetic installing pillars

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Chinese Chemical Letters 2024年第10期35卷 511-515页

作者： Xue-Zhi Wang Yi-Tong Liu Chuang-Wei Zhou Bei Wang Dong luo Mo Xie Meng-Ying sun Yong-Liang Huang Jie luo Yan Wu Shuixing Zhang Xiao-Ping Zhou Dan Li department of Radiology The First Affiliated Hospital Jinan University College of Chemistry and Materials Science and Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications Jinan University department of Medicinal Chemistry Shantou University Medical College department of Anesthesiology The First Affiliated Hospital of Sun Yat-sen University

Post-synthetic installation strategy is an effective approach to improve the functions of metal-organic frameworks（MOFs）. Herein, a pair of chiral MOFs is successfully constructed through solvothermal subcomponent self-assembly and exhibit circularly polarized luminescence（CPL）. These MOFs contain coordinatively unsaturated Zn sites and channels, which allow the installation of pyridyl-terminated pillars into the original structure. Such a post-synthetic installation process reinforces the MOFs' rigidity and increases the photoluminescence quantum yields（PLQYs）. Furthermore, the luminescence dissymmetry factors(glum) of these post-modified MOFs are amplified after installing the pillars. This work provides an appealing strategy for boosting the CPL performance of chiral MOFs.

关键词： Chiral metal-organic frameworks Chirality transfer Circularly polarized luminescence Post-synthetic installation Pyridyl-terminated pillars