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Search Results: 1 - 10 of 23449 matches for " Jiulin Shi "
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Effect of atmospheric environment on the attenuation coefficient of light in water
Juan Liu,Jiulin Shi,Yijun Tang,Kaixing Zhu,Yuan Ge,Xuegang Chen,Xingdao He,Dahe Liu
Physics , 2014,
Abstract: The attenuation coefficient of 532 nm light in water under different atmospheric conditions was investigated. Measurements were made over a two-year period at the same location and show that the attenuation coefficient is significantly influenced by the atmospheric environment. It is lowest when the atmospheric pressure is high and temperature is low, and is highest when the atmospheric pressure is low and temperature is high. The maximum attenuation coefficient of pure water in these studies was about three times the minimum value. The mechanism of the phenomena is discussed. These results are also important in underwater acoustics.
Possible dynamics of the Tsallis distribution from a Fokker-Planck equation (I)
Jiulin Du
Physics , 2009, DOI: 10.1088/1674-1056/19/4/040501
Abstract: The dynamical property of the Tsallis distribution is studied from a Fokker-Planck equation. For the Langevin dynamical system with an arbitrary potential function, Markovian friction and Gaussian white noise, we show that no possible nonequilibrium dynamics can use the Tsallis distribution for the statistical description. The current form of the Tsallis distribution stands for a simple isothermal situation with no friction and no noise.
A new form of Tsallis distribution based on the probabilistically independent postulate
Jiulin Du
Physics , 2009, DOI: 10.1088/1674-1056/19/7/070501
Abstract: The current form of Tsallis distribution for a Hamiltonian system with an arbitrary potential is found to represent a simple isothermal situation. In this letter, the q-exponential of a sum can be applied as the product of the q-exponential based on the probabilistically independent postulate employed in nonextensive statistical mechanics. Under this framework, a new form of Tsallis distribution is suggested. It is shown that the new form of Tsallis distribution can supply the statistical description for the nonequilibrium dynamical property of the Hamiltonian system governed by an arbitrary potential, and it is found to be one potential statistical distribution for the dark matter.
Property of Tsallis entropy and principle of entropy increase
Jiulin Du
Physics , 2008,
Abstract: The property of Tsallis entropy is examined when considering tow systems with different temperatures to be in contact with each other and to reach the thermal equilibrium. It is verified that the total Tsallis entropy of the two systems cannot decrease after the contact of the systems. We derived an inequality for the change of Tsallis entropy in such an example, which leads to a generalization of the principle of entropy increase in the framework of nonextensive statistical mechanics.
The Chandrasekhar condition of the equilibrium and stability for a star in the nonextensive kinetic theory
Jiulin Du
Physics , 2006, DOI: 10.1016/j.newast.2006.06.004
Abstract: The idea of Chandrasekhar condition of the equilibrium and stability for a star is revisited in the nonextensive kinetic theory based on Tsallis entropy. A new analytical formula generalizing the Chandrasekhar condition is derived by assuming that the stellar matter is kinetically described by the generalized Maxwell-Boltzmann distribution in Tsallis statistics. It is found that the maximum radiation pressure allowed at the center of a star of a given mass is dependent on the nonextensive parameter q. The Chandrasekhar condition in the Maxwellian sense is recovered from the new condition in the case of q=1.
Test of Nonextensive Statistical Mechanics by Solar Sound Speeds
Jiulin Du
Physics , 2006, DOI: 10.1209/epl/i2006-10196-3
Abstract: To check the validity of the theory of nonextensive statistical mechanics, we have investigated the nonextensive degree of the solar interior and have tried to find the experimental evidence by helioseismological measurements that q is different from unity. We are able to derive a parameter for providing a lower limit to the nonextensive degree inside the sun that can be uniquely determined by the solar sound speeds measured by helioseismology. After calculating the parameter by using the solar sound speeds, we get the lower limit of(1-q)not less than 0.1902 for all solar radii between 0.15R(sun) and 0.95R(sun) and (1-q)approximately equal to 0.4 for the out layers extending from 0.75R(sun)to 0.95R(sun).Thus, the result that the nonextensive parameter q is significantly different from unity has received the support by the experiment measurements for the solar sound speeds in the helioseismology.
Transition state theory: a generalization to nonequilibrium systems with power-law distributions
Jiulin Du
Physics , 2011, DOI: 10.1016/j.physa.2011.11.009
Abstract: Transition state theory (TST) is generalized for the nonequilibrium system with power-law distributions. The stochastic dynamics that gives rise to the power-law distributions for the reaction coordinate and momentum is modeled by the Langevin equations and corresponding Fokker-Planck equations. It is assumed that the system far away from equilibrium has not to relax to a thermal equilibrium state with Boltzmann-Gibbs distribution, but asymptotically approaches to a nonequilibrium stationary-state with power-law distributions. Thus, we obtain a generalization of TST rates to nonequilibrium systems with power-law distributions. Furthermore, we derive the generalized TST rate constants for one-dimension and n-dimension Hamiltonian systems away from equilibrium, and receive a generalized Arrhenius rate for the system with power-law distributions.
What does the nonextensive parameter q stand for in self-gravitating systems ?
Jiulin Du
Physics , 2004, DOI: 10.1007/s10509-006-9199-4
Abstract: It is natural important question for us to ask what the nonextensive parameter stands for when Tsallis statistics is applied to the self-gravitating systems. In this paper, some properties of the nonextensive parameter and Tsallis equilibrium distribution for the self-gravitating system are discussed in the framework of nonextensive kinetic theory. On the basis of the solid mathematical foundation, the nonextensive parameter can be expressed by a formula with temperature gradient and the gravitational potential and can be presented the physical meaning with regard to the non-isothermal (nonequilibrium stationary state) nature of the systems with long-range interactions. We come to the conclusion that Tsallis equilibrium distribution is corresponding to the physical state of self-gravitating system at the hydrostatic equilibrium.
Jeans criterion and nonextensive velocity distribution function in kinetic theory
Jiulin Du
Physics , 2004, DOI: 10.1016/j.physleta.2003.11.047
Abstract: The effect of nonextensivity of self-gravitating systems on the Jeans criterion for gravitational instability is studied in the framework of Tsallis statistics. The nonextensivity is introduced in the Jeans problem by a generalized q-nonextensive velocity distribution function through the equation of state of ideal gas in nonextensive kinetic theory. A new Jeans criterion is deduced with a factor that, however, differs from that one in Ref.[21] and new results of gravitational instability are analyzed for the nonextensive parameter q. An understanding of physical meaning of q and a possible seismic observation to find astronomical evidence for a value of q different from unity are also discussed.
Jeans criterion in nonextensive statistical mechanics
Jiulin Du
Physics , 2004, DOI: 10.1016/j.physa.2003.11.027
Abstract: The Jeans gravitational instability in nonextensive statistical mechanics is studied and a general form of the generalized Jeans criterion is obtained that is related to the q-function . In this approach, the nonextensive model of classical ideal gas is applied to the Jeans problem instead of the ordinary one in extensive statistical mechanics and the generalized critical wavelength to describe the gravitational instability is deduced. This nonextensive modification of the Jeans criterion leads to a new critical length that depends not only on the nonextensive parameter q but also on the dimension D and the total particle numbers N of the system. When, the Jeans length is perfectly recovered. We also give the nonextensive parameter q a physical interpretation that represents an isothermal process of the gas, corresponding to the state of complete mixing, but 0< q <1 is nonisothermal, corresponding to the state of incomplete mixing, it measures the degree of mixing.
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