Showing papers in "Physica D: Nonlinear Phenomena in 1974"

TL;DR: In this article, the authors introduce even and odd coherent states, where the transition amplitudes between the energy levels of a singular nonstationary oscillator in the case of constant frequency in the remote past and future and generating functions for these amplitudes are obtained, by a method similar to the usual coherent-state method.

TL;DR: In this paper, a systematic expansion for the expectation value of a stochastic process is given, where the expansion parameter is the product of the magnitude of the fluctuations and their auto-correlation time.

TL;DR: In this paper, a relaxation-time model is proposed for the collisions term of the relativistic Boltzmann equation for a single-component gas, and the resultant equation is solved as a power series in the relaxation time and this solution is used to calculate the transport coefficients for the gas.

TL;DR: In this article, a transformation for a triangular lattice in the space of Ising-spin hamiltonians with short-range forces was constructed and evidence was presented that this transformation exhibits a fixed point corresponding to a hamiltonian with dominant nearest-neighbour interaction.

TL;DR: In this paper, a hot-wire-based line source was used to measure the thermal conductivity of gases up to 800°C and 400 atm in an absolute way.

TL;DR: The Langevin equation for a spherical brownian particle from the equations governing fluctuating hydrodynamics was derived in this paper for the case of a sphere with a time-dependent velocity through a fluid in nonstationary and nonhomogeneous flow.

TL;DR: In this article, the generalization of the Faxen theorem for the force on a sphere in an incompressible fluid to the general nonstationary case derived in a previous paper is further extended to the case of a compressible fluid.

TL;DR: In this article, a projection operator which reduces quantities to their expectation value is introduced and an exact integro-differential equation for the expectation value of the stochastic process is derived.

TL;DR: In this article, the Van der Waals model of a fluid is equivalent to the hard-sphere model, and the applicability of this model for the interpretation of transport coefficients of real dense fluids is rigorously tested using expressions for dense hardsphere transport coefficients given by Enskog theory but corrected for the effects of correlated molecular motions.

TL;DR: In this paper, the scaling laws of Van der Waals' equation of state have been studied in the critical region of gases and their consequences for the description of thermodynamic data of fluids in this critical region have been discussed.

TL;DR: In this article, the authors used molecular dynamics evidence for logarithmic terms in the density expansion for the diffusion coefficient of the 2-dimensional Lorentz gas to obtain the long-time behavior of the velocity autocorrelation function.

TL;DR: In this article, the 1/f noise in the open circuit thermo e.m.f. of intrinsic germanium is explained by the mobility of free charge carriers of ionic aqueous solutions.

TL;DR: In this paper, the transport coefficients for single component Fermi-Dirac and Bose-Einstein gases are calculated using the relativistic relaxation-time model developed in the previous paper.

TL;DR: The origin and physical meaning of the scaling and homogeneity hypotheses in the theory of equilibrium critical phenomena are discussed in this article, and the connection between this scaling picture and the recent renormalization-group theory is mentioned briefly.

TL;DR: In this article, a statistical theory is given for the surface material coefficients characterizing the dielectric properties of thin island films, expressed in terms of correlation functions describing the distribution of the islands on the surface and the distribution over the various shapes of the island.

TL;DR: In this article, the linear response technique of Kubo is extended to treat the response of a system to quadratic order in the external field and nonlinear equations of motion for a set of slowly varying macroscopic variables, a ( t ), are obtained.

TL;DR: In this paper, a new theory of propagation and scattering of light in fluids is formulated based on a resummation of the Kirkwood-Yvon series expansion for the dielectric constant.

TL;DR: In this paper, a description of the two-component lattice-gas model is presented, which combines the essential features of the lattice theory of Guggenheim for a two component system and lattice gas model for a one component system.

TL;DR: In this article, an expression for the Van der Waals force between two semi-infinite bodies with small surface irregularities was derived for the plane-plane and plane-sphere configuration.

TL;DR: In this paper, a set of 32 general parameters was used to describe 344 atomic levels in 8 spectra, with satisfactory precision, the mean error being 113 cm−1. But the results were obtained only when a new interaction term α2L(L + 1) was introduced in addition to the usual Trees correction α1L′(L′ + 1), L′ being the orbital quantum number of the dn−1 parent.

TL;DR: In this article, measurements of the temperature dependence of the magnetic field effect on the thermal conductivity were presented for the gases N 2, CO, CH 4 and CD 4 between 85 and 300K and for HD in the temperature region between 40 and 300 K.

TL;DR: In this paper, the self-diffusion of a tagged particle in a 3-dimensional fluid of identical particles cannot be described by a linear diffusion equation which contains corrections to Fick's law proportional to ▿4n, ▿6n, etc.

TL;DR: In this article, it was shown that fluctuations of intermediate wavelengths are the crucial effect producing non-classical exponent (intermediate wavelengths are much larger than the range of forces, much smaller than the correlation length).

TL;DR: In this paper, the authors used PVT and sound-velocity data for liquid argon, at temperatures from 90 to 150 K, to calculate the following properties at pressures up to the melting curve (P max = 3000 atm): isothermal compressibility, thermalexpansion coefficient, thermal pressure coefficient, configurational internal energy and specific heat ratio (C P / C V ).

TL;DR: In this article, the authors investigated the pressure broadening of the depolarized Rayleigh line at room temperature for the gases normal H 2, para H 2, HD, normal D 2, N 2, CO, CO 2 and OCS.

TL;DR: In this paper, pressure broadening of the rotational Raman lines at room temperature is investigated for the hydrogen isotopes for H 2, measurements have been carried out as a function of orthopara composition Evidence has been found that the contribution of resonance collisions to the widths of some of the Raman line exceeds 40%

TL;DR: In this paper, a mass-action law for the formation of bound pairs, triples, etc. is derived, which takes into account not only the discrete part of the energy spectrum but also the interactions corresponding to the continuous spectrum (e.g., free-free and free-bound interaction).

TL;DR: In this paper, expressions for the static dielectric permittivity analogous to the Kirkwood-Frohlich equation were derived for liquid crystals with uniaxial symmetry, and they were shown to be equivalent to the permittivities of liquid crystals in general.

TL;DR: In this article, the authors extend the calculation of the free energy in systems with separable interactions given in a previous paper, to a more general class of systems characterized by a hamiltonian, which contains a number of separable two-particle operators of the antiferromagnetic type in addition to separable ferromagnetic interactions and one particle operators.

TL;DR: In this paper, van der Waals's theory of capillarity was studied in the light of his own remark that he set out to determine the molecular pressure in Laplace's theory.