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Microwave peak absorption frequency of liquid

Science china(physics,Mechanics & Astronomy) 2008年第9期51卷 1254-1263页

作者： han guangze1 & chen mingdong2 1 department of physics,south china university of technology,guangzhou {3.40,china 2 guangzhou Auto College,south china university of technology,guangzhou 510800,china 1. department of physics South China University of Technology Guangzhou 510640 China 2. guangzhou Auto College South China University of Technology Guangzhou 510800 China

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

关键词： microwave-assisted extraction microwave heating relaxation time liquid viscosity peak absorption fre-quency

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Properties of Rotating Neutron Stars in the Relativistic σ-ω Model

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Communications in Theoretical physics 2004年第1期41卷 51-54页

作者： WEN De-Hua~(1,2) chen Wei~3.WANG Xian-Ju~1 AI Bao-Quan~1 LIU Guo-Tao~1 LIU Liang-Gang~1 1 department of physics,Zhongs{3. university,guangzhou 510275,china2 department of physics,south china university of technology,guangzhou 510641,china3.department of physics,Jinan university,guangzhou 51063.,china department of physics Jinan University Guangzhou 510632 China

The properties such as the moment of inertia,the surface redshift and the radius of gyration of rotatingneutron stars in the relativistic σ-ω model are studied with the Hartle’s *** relation between the angularvelocity of the fluid relative to the local inertial frame and the uniform angular velocity relative to the infinite iscalculated.

关键词： relativistic σ-ω model rotating neutron star equation of state

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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,{3. china Normal university,guangzhou 510006,china 2 department of Information Science and technology,SUN Yat-sen university,guangzhou 510026,china 1. School of physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China2. Department of Information Science and Technology SUN Yat-sen University Guangzhou 510026 China

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

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Superconductivity of small metal grains

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Science china(physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 chen Zhiqian2 & ZHU Shunquan1,3.1. department of physics, S{3.ghai Normal university, S{3.ghai 20023., china 2. department of physics, southwest Normal university, Chongqing 400715, china 3. department of Computer and Electric {13., S{3.ghai Business School, S{3.ghai 201400, china 1. department of physics Shanghai Normal University 200234 Shanghai China 2. department of physics Southwest Normal University 400715 Chongqing China 3. department of Computer and Electric technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

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Study on the two and three-parameter working stability regions of 3.-TZP suspension

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Science china(Technological Sciences) 2006年第5期49卷 547-568页

作者： chen Youqiang1, 2, ZhanG Xinni3. chen Sha’ou3.& QI Ping3.1. {3. of Chemistry, Qingdao university, Qingdao 266071, china 2. {3. of Chemistry, Tsinghua university, Beijing 100084, china 3. {3. of physics, Qingdao university, Qingdao 266071, china 1. department of Chemistry Qingdao University Qingdao 266071 China 2. department of Chemistry Tsinghua University Beijing 100084 China 3. department of physics Qingdao University Qingdao 266071 China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3.-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3.-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3.-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3.-TZP, suspension, stability, DLVO theory, interparticle potential energy.

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Degradation of nitrobenzene in wastewater by γ-ray irradiation

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Journal of Environmental Sciences 2004年第3期16卷 364-366页

作者： ZhanG Shu juan 1, FENG Shao hong 1, YU han qing 1,* , LI Qian rong 2 (1 department of Chemistry, {3. of Science & technology of china, Hefei 23.026, china. 2 Research Center for physics & Chemistry, {3. of Science & technology of china, Hefei 23.026, china) department of Chemistry University of Science & Technology of China Hefei 230026 China.

The degradation of nitrobenzene(NB) by γ ray irradiation was studied. The influences of dose rate and initial NB concentration were investigated in details. At a dose rate of 55 Gy/min, the degradation kinetics was pseudo first order at NB concentrations from 0 2 mmol/L to 4 0 mmol/L. At an initial NB concentration of 0 8 mmol/L, the degradation of NB at various dose rates also followed pseudo first order kinetics. Dissolved oxygen was found to have a positive effect on NB degradation. The degradation products were identified as nitrophenol, nitrosobenzene, and hydroquinone, and so on. Based on the product analysis, possible degradation pathways of nitrobenzene were proposed.

关键词： degradation irradiation nitrobenzene(NB) kinetics

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A fractal study for nucleate pool boiling heat transfer of nanofluids

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Science china(physics,Mechanics & Astronomy) 2010年第1期53卷 30-37页

作者： XIAO BoQi 1 , JIANG GuoPing 2 & chen LingXia 1 1 department of physics and Electromec{3.ical Engineering, Sanming university, Sanming 3.5004, china 2 Earthquake Engineering Research Test Center, guangzhou university, guangzhou 510405, china 1. department of physics and Electromechanical Engineering Sanming University Sanming 365004 China2. Earthquake Engineering Research Test Center Guangzhou University Guangzhou 510405 China

In this paper, a fractal model for nucleate pool boiling heat transfer of nanofluids is developed based on the fractal distribution of nanoparticles and nucleation sites on boiling surfaces. The model shows the dependences of the heat flux on nanoparticle size and the nanoparticle volume fraction of the suspension, the fractal dimension of the nanoparticle and nucleation site, temperature of nanofluids and properties of fluids. The fractal model predictions show that the natural convection stage continues relatively longer in the case of nanofluids. The addition of nanoparticles causes a decrease of the pool nucleate boiling heat transfer. The nucleate pool boiling heat transfer coefficient is decreased by increasing particle concentration. An excellent agreement between the proposed model predictions and experimental data is found. The validity of the fractal model for nucleate pool boiling heat transfer is thus verified.

关键词： nanofluid nucleate pool boiling fractal heat transfer

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Density-functional formula for strongly correlated systems

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Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, han Rushan2 and chen Nanxian1(1. {3. of physics, Tsinghua university, Beijing 100084, china 2. {3. of physics, Peking university, Beijing 100871, china) department of physics Tsinghua University Beijing 100084 China department of physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

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Reply to“Comment on ‘Recent progress in thermodynamics of radiation—Exergy of radiation,effective temperature of photon and entropy constant of photon'”

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Science china(Technological Sciences) 2010年第3期53卷 878-880页

作者： chen ZeShao 1,MO SongPing 1,2 &HU Peng 1 1department of Thermal Science and Energy Engineering,university of Science and {3. of china,Hefei 23.027,china 2 Faculty of Material and Energy,Guangdong university of {3.,guangzhou 510006,china 1. department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 China2. Faculty of Material and Energy Guangdong University of Technology Guangzhou 510006 China

Two counterexamples in Liu's comment on'Recent Progress in Thermodynamics of Radiation—Exergy of radiation,effective temperature of photon and entropy constant of photon'are analyzed and the incorrect applications of the related concepts are *** similarities and differences between the concepts of the effective temperature of photon,the exergy of spectral radiation,the entropy constant of photon and the macroscopic concepts of temperature,exergy,and entropy are further *** duality of radiant energy,micro-state quantum characteristic and macro-state thermal characteristic is presented.

关键词： thermodynamics of radiation photon entropy

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Electronic structure and magnetism of R(Fe,Si)_(12) (R=Y,Nd)

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Science china(physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： SUN Guang’ai1, chen Bo1, DU Honglin2, FAN Zhijian1, GAO Tao3.& QI Xinhua3.. Institute of Nuclear physics and Chemistry, china Academy of Engineering physics, Mianyang 621900, china 2. department of physics, Peking university, Beijing 100871, china 3. Institute of Atomic and Molecular physics, Sichuan university, chengdu 610065, china 1. Institute of Nuclear physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China 2. department of physics Peking university Beijing 100871 China 3. Institute of Atomic and Molecular physics Sichuan University Chengdu 610065 China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, Si)12 compounds (R = Y, Nd) are calculated using the method. The distribution of Si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOS) and partial density of states (PDOS) for different crystal sites Si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10Si2 (R = Y, Nd) are larger than those of RFe10M2 (M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. Si(8j) reduce the mag-netic moments of Fe at three sites, however, Si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of Si atoms according to spin fluctuation of DOS at Fermi level.

关键词： (L)APW+lo method R(Fe Si)12(R = Y Nd) magnetic moment Density of state.

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