共查询到20条相似文献,搜索用时 31 毫秒
1.
《Physica A》1996,231(4):551-574
We consider the form of the rebound velocity, ν0, particle velocity, ν, and height, h, probability density functions (PDFs) for the one-dimensional motion of a single particle on a sinusoidally oscillating base. The motion is considered in the limit of high excitation (vibration frequency ⪢ collision rate). Experimentally, we find that these PDFs are well-approximated by Pν0(ν0) ∞ ν0 exp(− αν02), a Gaussian Pν(ν) ∞ exp(− αν2) and a Boltzmann-type function Ph(h) ∞ exp(− 2αgh), where α is a constant and g is the acceleration due to gravity. We develop an analytical model which accurately predicts the general form for the rebound velocity PDF; the other two PDFs are then analytically shown to follow as a consequence. Scaling laws for the particle granular temperature with peak base velocity and particle-base restitution coefficient, determined from previous work, can also be predicted from the PDF. A fine scale “spiky” structure in the rebound velocity PDF is found, using numerical simulations, to be a consequence of resonance phenomena between the particle and vibrating base. Good agreement between scaling laws from the theory and simulation is found but insufficient data is obtainable to derive accuracy exponents experimentally. 相似文献
2.
We consider the effects of an external potential -h∑f(S x ) withh>0,f increasing, on the equilibrium state of a system with a Hamiltonian of the form $$H^0 (S) = \sum\limits_{\left\langle {xy} \right\rangle } {\Phi (S_x - S_y )} ,S_x \in R,x \in Z^d ,d \geqslant 3$$ Φ even and convex, e.g.,Φ(t)=1/2t 2 andf(t)=signt. This can be thought of as a model of the interactions between a random interface S x and a “soft” wall. We show that the random surface is (entropically) repelled to infinity for allh>0, i.e., with probability one,S x ≥K, for anyK ε R. 相似文献
3.
I.S. Osad'ko 《Optics Communications》2010,283(23):4671-4675
A single two-level molecule driven by CW-laser field and a photomultiplier tube (PMT) are considered as two parts of the united dynamical system connected with each other by photons of molecular fluorescence. Each PMT is characterized by a rate α of photo-effect and by a rate β of PMT recovery. A theory for the photon distribution function wN(t) and for the photoelectric pulse distribution function fn(t) for such a system is built up. If times 1/ α and 1/ β characterizing PMT are much shorter as compared to the average time interval 1/ k between two successively emitted photons of fluorescence, the photon and the photoelectron distribution functions coincide with each other, i.e. fn(t) ≅ wN(t). A relation between wN(t) and fn(t) is studied in detail for the case in which PMT works slower as compared to the rate k of photon emission, i.e. at 1/ α, 1/ β ≥ 1/ k. 相似文献
4.
A. Kiliç K. Kiliç M. Olutaş A. Altinkok 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(8):1-18
We study the effect of multiple interpenetrating pinning arrays on the vortex motion in the presence of an ac driving force, f d (t), by using extensive molecular dynamics (MD) simulations. Firstly, the response to a square ac wave f d (t) has been explored for the vortices interacting with a periodic square pinning array which has different pinning strengths and sizes. The effect of the type of an ac drive and its amplitude on the oscillatory dynamics of vortices have been investigated in detail. For very low displacements of the vortices, we have found that the single-particle model can produce results analytically similar to the ones obtained by the MD simulations. It is shown that the collective motion of vortices can be controlled easily by varying the number of multiple interpenetrating square pinning lattices (N SPSL). A regular sequence of peaks has been observed for N SPSL = 3 in the time evolution of the average velocity of the vortices (i.e., V? x - t curves). The number of peaks (N peak) strongly depends on the magnitude of f d (t), and increases with increasing the magnitude of f d . The close relation between N peak and f d is considered as an indication of controlling vortex motion in a multiple periodic pinning structure. Finally, the variation of the power spectrum of noise S(ν) with N SPSL has been investigated. For N SPSL = 3, it has been found that the plastic motion of the row of vortices evolves at low frequencies, i.e., 1/ν behavior, whereas, at high frequencies, S(ν) shows a typical behavior of Gaussian white noise. 相似文献
5.
D. Alde F. G. Binon M. Boutemeur C. Bricman S. V. Donskov M. Gouanère A. V. Inyakin V. A. Kachanov G. V. Khaustov E. A. Knapp A. A. Kondashov A. V. Kulik G. L. Landsberg A. A. Lednev V. A. Lishin J. P. Peigneux S. A. Polovnikov V. A. Polyakov M. Poulet Yu. D. Prokoshkin S. A. Sadovsky V. D. Samoylenko P. M. Shagin A. V. Shtannikov A. V. Singovsky J. P. Stroot V. P. Sugonyaev 《Zeitschrift fur Physik C Particles and Fields》1995,66(3):375-378
A high-statistics study of the π0π0-system produced in the π- p→π0π0 n reaction at 38GeV/c has been carried out at the IHEP accelerator using the GAMS-2000 multiphoton spectrometer. A partial-wave analysis which includesS, D 0, D? andD + waves has been performed in the |t|-range up to 1 (GeV/c)2. TheS */f 0(980) resonance is seen as a dip in theS-wave amplitude at small |t|. A distinct peak with a mass of 997±5MeV and a width of 48±10MeV is observed in theS-wave at |t|>0.3 (GeV/c)2. The production cross sections are measured. 相似文献
6.
I. V. Ajinenko S. A. Akimenko G. I. Britvich I. G. Britvich K. V. Datsko A. P. Filin A. V. Inyakin A. S. Konstantinov V. F. Konstantinov I. Ya. Korolkov V. M. Leontiev V. P. Novikov V. F. Obraztsov V. A. Polyakov V. I. Romanovsky V. I. Shelikhov N. E. Smirnov M. M. Soldatov O. G. Tchikilev E. A. Usenko M. V. Vasiliev E. V. Vlasov V. I. Yakimchuk O. P. Yushchenko V. N. Bolotov S. V. Laptev V. A. Lebedev A. R. Pastsjak A. Yu. Polyarush R. Kh. Sirodeev 《Physics of Atomic Nuclei》2003,66(1):105-109
The decay K ? → μ ? νπ 0 has been studied using in-flight decays detected with the ISTRA+ setup operating in the 25-GeV negative secondary beam of the U-70 PS. About 112K events were used for the analysis. The λ + and λ 0 slope parameters of the decay form factors f +(t) and f 0(t) have been measured: λ +=0.0321±0.004(stat.)±0.002(syst.), λ 0=0.0209±0.004(stat.)±0.002(syst.); the correlation dλ 0/dλ +=?0.46. The limits on the possible tensor and scalar couplings have been derived: f T/f +(0)=?0.021±0.028(stat.)±0.014(theor.), f S/f +(0)=0.004±0.005(stat.)±0.005(theor.). 相似文献
7.
S.K. Ottarsson 《Journal of Geometry and Physics》1985,2(1):49-72
The main topic discussed in this paper is the following question: Given a Riemannian manifold M and a closed C1 curve f: S1 → M does there exist a (unique) solution of the heat equation ?tft = τ(ft) defined for all t ≧ 0 which is continuous at t = 0 along with its first S1-derivative and which coincides with f at t = 0. 相似文献
8.
A system of N particles $\xi ^N = x_1 ,\upsilon_1,...,x_N ,\upsilon _N )$ interacting self-consistently with one wave Z = A exp(iφ) is considered. Given initial data (Z (N)(0), ξ N (0)), it evolves according to Hamiltonian dynamics to (Z (N)(t), ξ N (t)). In the limit N → ∞, this generates a Vlasov-like kinetic equation for the distribution function f(x, v, t), abbreviated as f(t), coupled to the envelope equation for Z: initial data (Z (∞)(0), f(0)) evolve to (Z (∞)(t), f(t)). The solution (Z, f) exists and is unique for any initial data with finite energy. Moreover, for any time T>0, given a sequence of initial data with N particles distributed so that the particle distribution f N(0) → f(0) weakly and with Z (N)(0) → Z(0) as N → ∞, the states generated by the Hamiltonian dynamics at all times 0 ≤ t ≤ T are such that (Z (N)(t), f N(t)) converges weakly to (Z (∞)(t), f(t)). 相似文献
9.
J.W. Evans 《Physica A》1980,102(1):87-104
A class of initial value problems for a one-dimensional hard sphere gas is considered where a specified particle has a given distribution f(1)(z1; 0) and the rest are in equilibrium at t=0. An exact expansion is obtained for a certain n-particle reduced distribution function f(n)(z1;…;zn; t) in terms of the 1-particle reduced distribution function f(1)(z1; t) for the specified particle by starting with separate expressions for these functions in terms of f(1)(z1; 0). Expansions for the corresponding cluster functions are first obtained and then graph theoretic methods applied to obtain a solution. 相似文献
10.
A meson-theoretical model for the reaction π? p → π0π0 n for large π? momenta is developed which treats the final-state interaction between the two produced pions microscopically. For small momentum transfers, the squares of the S-wave amplitudes of the produced two-pion system show a dip for invariant twopion masses in the vicinity of the f 0(980) meson, while for momentum transfers ?t>0.2(GeV/c)2, the f 0(980) meson appears as a bump. The model provides a microscopic explanation of the long-standing puzzle seen by both the GAMS and the BNL experimental collaborations. 相似文献
11.
Ross D. Rosenwald Henry A. Hill Jerry D. Logan 《Journal of Quantitative Spectroscopy & Radiative Transfer》1984,31(3):221-234
One to six point Gaussian quadrature formulas have been computed for the roots and weight coefficients of the integrals, from zero to infinity, of the integrands f(x) exp(-|x?t|) and f(x)En(|x?t|). These are then tabulated as functions of t. Analytic formulas are given explicitly for one and two point quadratures for any n. The asymptotic behavior of the roots and weight coefficients is discussed. Estimates of errors for the quadratures are also given. 相似文献
12.
Diffusion activation energy versus the favourable energy in two-order-parameter model:A molecular dynamics study of liquid Al
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In the present work, we find that both diffusion activation energy Ea(D) and Ea(Sex) increase linearly with pressure and have the same slope (0.022±0.001 eV/GPa) for liquid Al. The temperature and pressure dependence of excess entropy is well fitted by the expression -Sex(T,P)/kB=a(P)+b(P)T+c(P)exp(Ef/kBT), which together with the small ratio of Ef/kBT leads to the relationship of excess entropy to temperature and pressure, i.e. Sex≈-cEf/T, where c is about 12 and Ef (=Δ E-PΔV) is the favourable energy. Therefore, there exists a simple relation between Ea(Sex) and Ef, i.e. Ea(Sex)≈cEf. 相似文献
13.
A. S. Schwarz 《Communications in Mathematical Physics》1974,39(1):33-48
It is shown that Møller matricesS ± and scattering matrixS in axiomatic field theory can be expressed through their adiabatic analogs. In particular, it is proved under certain conditions that \(S_ - = \mathop {s\lim }\limits_{\alpha \to 0} S_\alpha (0,\infty )W_\alpha \) whereW α is a trivial phase factor [i.e. a unitary operator of the form exp i / α ∝r(k)a + (k)a(k)dk]. Corresponding results in Hamiltonian approach are discussed. 相似文献
14.
F. Binon A. M. Blik S. V. Donskov S. Inaba V. N. Kolosov A. A. Lednev V. A. Lishin Yu. V. Mikhailov J. P. Peigneux V. A. Polyakov S. A. Sadovsky V. D. Samoilenko A. E. Sobol J. P. Stroot V. P. Sugonyaev K. Takamatsu T. Tsuru I. Fujii G. V. Khaustov H. Shimizu Y. Yasu 《Physics of Atomic Nuclei》2005,68(6):960-973
The ηη system produced in charge-exchange π ? p interaction at a momentum of 32.5 GeV/c is studied in an experiment performed with the GAMS-4π spectrometer at the 70-GeV accelerator of the Institute for High-Energy Physics (IHEP, Protvino). A partial-wave analysis is performed in the mass range between 1.1 and 3.9 GeV for ?t <0.2 (GeV/c)2, S, D, G, and J waves being taken into account in this analysis. The S wave has a complicated structure, displaying peaks at about 1.5 and 1.7 GeV. These peaks are associated with the f 0(1500) and f 0(1710) mesons. One of the solutions (preferable one) involves the f 0(2200) and f 2(1950) resonances. The mass region above 2.4 GeV is dominated by the G wave. A broad state of mass about 3 GeV and width 0.7 GeV is found in the J wave. The parameters of the resonances in question and their production cross sections are measured. 相似文献
15.
K. Yamada 《Physics letters. [Part B]》1980,97(1):156-158
We discuss the precise momentum dependence of the Ke3 form factor f+(t) by studying some of the recent experimental results on K0L → π± e? ν decays. The parametrization of f+(t) based on the assumption of K1-dominance can considerably improve the agreement of Sirlin's relation with existing data. 相似文献
16.
Ta-You Wu 《International Journal of Theoretical Physics》1975,14(5):289-294
The Umkehreinwand of Loschmidt and the Wiederkehreinwand of Zermelo have been reexamined. The former paradox depends on the augument that for a dynamical system, upon the reversal of the velocities of all the molecules, theH function retraces its sequence of values so thatdH/dt will change its sign. The latter paradox depends on the argument that theH function returns infinitely close to its value after a Poincare' quasi-period and therefore cannot be decreasing all the time. While the main contention of the two paradoxes is correct, that theH theorem is inconsistent with classical dynamical laws, the arguments there can be considerably simplified and the “paradoxes” answered more directly. If the distribution functionf(q K ,p K ,t) is governed by an equation which is time-reversal invariant (such as the Liouville equation for a closed dynamical system), then it can be shown immediately thatdH/dt=0,H=cons. In this case, both paradoxes disappear, but together with them, thedH/dt<0 part of theH theorem also has disappeared, i.e., there is no second law of thermodynamics. Iff(q K ,p K ,t) is governed by an equation which is not time-reversal invariant (such as the Boltzmann equation, or the Master Equation for Markovian processes), then (1) there is no argument forf andH(t) to retrace their sequence of values upon the reversal of all the velocities of the system, (2) there is no quasiperiod in whichf andH(t) return to their earlier values. In this case, both paradoxes disappear also, but then one must go beyond classical dynamics in order to maintain theH theorem. 相似文献
17.
Henry E. Kandrup 《International Journal of Theoretical Physics》1989,28(6):605-617
This paper defines, and then evaluates perturbatively, an information-theoretic notion of entropyS
2 for a system ofN interacting particles which assesses an observer's limited knowledge of the state of the system, assuming that he or she can measure with arbitrary precision all one-particle observables and correlations involving pairs of particles, but is completely ignorant of the form of any higher-order correlations involving three or more particles. By construction, thisS
2(t) involves only the reduced two-particle distribution functions, or density matrices,f
2(i,j) at timet, and, though the implementation of a subdynamics,dS
2
(t)/dt can be realized in terms of thef
2(i, j)'s at retarded timest–. A similar line of reasoning demonstrates that the most probable three-particlef
3(i,j, k) consistent with a knowledge of thef
2's is precisely thatf
3 suggested by the Kirkwood, or cluster, decomposition. 相似文献
18.
《Nuclear Physics A》1983,398(1):141-188
We present a formalism and some of its applications aimed at describing RPA-like correlations on top of a time-dependent mean field. These correlations correspond to the zero-point oscillations of collective modes orthogonal to the TDHF trajectory. They are not the result of some instantaneous local RPA equations but they evolve freely from some given initial conditions. A generalized time-dependent generator coordinate (TDGCM) variational formulation leads to explicit equations of motion for both f(q, t) and |φq(t〉 in |ψ(t)〉 = ∝dqf(q, t)|φq(t)〉, the correlated time-dependent wave functions. The q-distorted Slater determinants |φq(t)〉, obey well known TDHF equations of motion while f(q, t) obey a time-dependent generator coordinate integral equation. This last one is further simplified by the assumption of gaussian overlaps for the correlations, so that one can then solve for the time dependence of the correlations by evaluating a few TDHF trajectories differing by small amounts in the collective variables q considered. This TDGCM method is applied in a one-dimensional TDHF scheme. Momentum, energy and breathing fluctuations are studied, as well as their mutual interaction. We find that the fluctuations can be enlarged by an order of magnitude over the values predicted by pure TDHF. 相似文献
19.
20.
A. Asselah P. Dai Pra J. L. Lebowitz Ph. Mounaix 《Journal of statistical physics》2001,104(5-6):1299-1315
We investigate solutions to the equation ? t ?? $\mathcal{D}$ Δ?=λS 2?, where S(x, t) is a Gaussian stochastic field with covariance C(x?x′, t, t′), and x∈ $\mathbb{R}$ d . It is shown that the coupling λ cN (t) at which the N-th moment <? N (x, t)> diverges at time t, is always less or equal for $\mathcal{D}$ >0 than for $\mathcal{D}$ =0. Equality holds under some reasonable assumptions on C and, in this case, λ cN (t)=Nλ c (t) where λ c (t) is the value of λ at which <exp[λ ∫ t 0 S 2(0, s) ds]> diverges. The $\mathcal{D}$ =0 case is solved for a class of S. The dependence of λ cN (t) on d is analyzed. Similar behavior is conjectured when diffusion is replaced by diffraction, $\mathcal{D}$ →i $\mathcal{D}$ , the case of interest for backscattering instabilities in laser-plasma interaction. 相似文献