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Spontaneous ignition of corrugated cardboard under dynamic high radiant flux

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Defence Technology（防务技术） 2024年第10期40卷 65-77页

作者： Liu Liu Yan Gu Hong Yang Xing Wang Yang Zhou xiaogan Dai Yong Han Shanggang Wen Ming Li Congmei Lin Changgen Feng Fei Tang Yushi Wen Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621999China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China Institute of Applied physics and Computational Mathematics China Academy of Engineering PhysicsBeijing 100088China

Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme *** the more moderate radiant fluxes in conventional hydrocarbon fires,extreme events such as strong explosion,concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m^(2. level,creating a unique threat to *** study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods,under 10-cm dynamic high radiant fluxes ranging from 0.2.to 1.2. MW/m^(2. for 10 *** spontaneous ignition process at dynamic high radiant fluxes was recorded and *** ignition modes were found at the critical radiant flux of 0.4 MW/m^(2.,namely hot-gas spontaneous ignition and hot-residue piloted *** latter is not the focus of this paper due to its extremely small probability of *** research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition,lower ignition energy density,along with a corresponding rise in the critical mass flux and surface temperature at ignition *** simulation results are generally aligned with the experimental findings,despite some divergences may be attributed to model simplifications and parameter *** work contributes to a deeper insight into material behavior under extreme radiation,with valuable implications for fire safety and hazard assessment.

关键词： Extreme radiation Fire safety Corrugated cardboard Pyrolysis Ignition temperature

Output Rate of Atomic Four-Wave Mixing in Two-Component Bose-Einstein Condensate

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Communications in Theoretical physics 2004年第5期41卷 695-698页

作者： LI Jia-Hua~1 LI Wei-Bing~1 PENG Ju-Cun~2.1 department of physics,Huazhong {2. of Science and Technology,Wuhan 430074,china2.department of physics,xiaogan Normal {2.,xiaogan 4.2.00,china department of physics Xiaogan Normal University Xiaogan 432100 China

In this letter,following the proposal of Heurich et al.[***.A63(2.01)033605],we analyze anddiscuss output rate of atomic four-wave mixing in the two-component Bose-Einstein condensate under the condition ofthe steady *** results show that the magnitude of the signal beam increases with the increase of the intensityof the probe beam,up to a saturated value,then it decreases as the probe beam *** influence of theinteraction range on the signal beam is also *** particular,it is worth while pointing out that in contrast tothe previous solutions,our obtained analytical solutions are of very simple and explicit forms,which open the door forfurther investigating the related physical mechanisms.

关键词： atomic four-wave mixing steady state Bose-Einstein condensate

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. department of physics, Tsinghua {2., Beijing 100084, china 2. department of physics, Peking {2., 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.

Effect of an impurity on 3-electron quantum dots in magnetic fields

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Science china(physics,Mechanics & Astronomy) 2004年第5期47卷 521-530页

作者： LIU Yimin1,2. HUANG Gangming1 & BAO Chengguang1 1. department of physics, Zhongshan {2., Guangzhou 5102.5, china 2. department of physics, Shaoguan {2., Shaoguan 512.05, china 1. department of physics Zhongshan University 510275 Guangzhou China 2. department of physics Shaoguan University 512005 Shaoguan China

The ground-state property of a 2.dimensional 3-electron quantum dot (QD) subjected to an external magnetic fieldB and affected by an impurity is studied. The impurity is located at thez-axis by a distanced from the plane of the dot. The evolution of the angular momentumL o and the spinS o of the ground state in accordance withB andd has been calculated, and the results are summarized and plotted in a (L o,S o) diagram. The spatial distribution of the electrons (the size and the geometric features) and the optical absorption have also been investigated. The (L o S o) diagram indicates thatL o andS o may jump whend and/orB vary. It was found that, due to the constraints arising from symmetry, each symmetric geometry is accessible only to a specific group of states having specificL o andS o.

关键词： quantum dot, ground state, charged impurity, magnetic field.

Direct CP violation in hadronic B decays

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Science china(physics,Mechanics & Astronomy) 2006年第3期49卷 357-366页

作者： HONG Bihai1,2.& Lü Caidian3 1. department of physics, Lishui {2., Lishui 32.000,china 2. department of physics, Shanghai Jiaotong {2., Shanghai 2.0030, china 3. Institute of High Energy physics, Beijing 100049,china department of physics Lishui University Lishui 323000 China department of physics Shanghai Jiaotong University Shanghai 200030 China Institute of High Energy physics Beijing 100049 China

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on kT factorization, using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.

关键词： CP violation hadronic B decay factorization.

Stochastic resonance in surface catalytic oxidation of carbon monoxide induced by colored noise

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Science china Chemistry 2004年第2期47卷 106-112页

作者： GONG Yubing1,2. HOU Zhonghuai1 & XIN Houwen1 1. department of Chemical physics, {2. of Science and Technology of china, Hefei 2.002., china 2. department of physics, Yantai Teachers {2., Yantai 2.402., china 1. department of Chemical physics University of Science and Technology of China 230026 Hefei China 2. department of physics Yantai Teachers University 264025 Yantai China

The dynamical behavior of surface catalytic oxidation reaction of Pt(110)/CO+O2.modulated by colored noise, under the condition of specific temperature, has been investigated when the partial pressure of CO gas is near the supercritical Hopf bifurcation point. By computer simulation the oscillation and stochastic resonance induced by colored noise are observed. The influences of the intensity and correlation time of colored noise on stochastic resonance are discussed. The range of sensitivity of the system to the environmental fluctuation is analyzed.

关键词： colored noise, stochastic resonance, surface catalytic reaction of Pt(110)/CO+O2. supercritical Hopf bifurcation, signal-to-noise ratio (SNR).

Internal noise stochastic resonance in CO oxidation on nm-sized palladium particles

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Science china Chemistry 2005年第5期48卷 395-401页

Based on a stochastic mesoscopic model, the influence of internal noise on the oscillatory kinetics of the catalytic oxidation of CO on nm-sized palladium particles is studied, using the chemical Langevin equations, Poisson approximation algorithm, and exact stochastic simulation algorithm. The reaction rate oscillations are of stochastic nature due to considerable internal noise in such mesoscopic systems. It is found that the performance of the stochastic oscillations undergoes a maximum with the variation of internal noise level for a given CO partial pressure, which demonstrates the occurrence of internal noise stochastic resonance. This phe-nomenon implies that optimal internal noise would favor the reaction rate oscillation of CO oxi-dation on nm particles. Such a phenomenon is robust to the change of external parameters, such as CO pressures.

关键词： nanometer-sized palladium particles, surface catalytic CO oxidation, internal noise, stochastic resonance, chemical Langevin equation.

Anisotropic effect on the vibronic reduction factors

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Chinese Science Bulletin 2006年第21期51卷 2553-2558页

作者： QIU Qing-chun1,2.& QIAO Fen1,2.1. department of physics and IT, Medical College, Shantou {2.,Shantou 515041, china 2. department of physics, Shantou {2., Shantou 515063, china department of physics and IT Medical College Shantou University Shantou 515041 China department of physics Shantou University Shantou 515063 China

The reduction factors p and q defined by Ham in the Ee JT system and their relation 2.-p=1 have been well accepted and the concept of reduction factors is widely used in the studies of vibronic coupling. However, when the system is under the anisotropic conditions, the reduction factors and their relation will change accordingly. The first-order reduction factors p and q of Ee system were further studied using the method of unitary transformation here. The relation between p and q proposed by Ham was investigated under both conditions of the linear coupling and the anisotropic effects. The result demonstrated that the relation of 2.-p=1 was only correct for the linear vibronic coupling, but not correct when the anisotropic effect was considered. This result suggested that the anisotropic effect influence considerably the reduction factors, and hence the physical properties of materials. Our method could be also applied to other JT systems, especially the highly symmetric JT systems involving C60 molecules.

关键词：电子振动耦合声子交迭 Jahn-Teller效应各向异性

Study on the two and three-parameter working stability regions of 3Y-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. department of Chemistry, Qingdao university, Qingdao 2.6071,{2. 2. department of Chemistry, Tsinghua university, Beijing 100084,{2. 3. department of physics, Qingdao university, Qingdao 2.6071,{2. 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 3Y-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 3Y-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 3Y-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： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.