摘要:

The anomalous thermodynamic behavior of fluids near the critical point can be described in terms of sealing laws. In this paper we consider two critical region equations of state, to be referred to as the NBS equation and the Linear Model parametric equation, that satisfy the scaling laws. A complete formulation of the thermodynamic properties in terms of the two equations is given. The statistical methods used for fitting these equations to experimental data are described. Each of the equations is fitted to experimental equation of state data for six fluids, namely He3, He4, Xe, CO2, O2, and H2O. An evaluation of the recorded experimental material is included. We find that the two equations represent the experimental data in the range ‖T−Tc‖/Tc<0.03 and ‖p−pc‖/pc< 0.25 equally well and that the exponents and amplitudes of the power laws deduced from the two equations agree closely. The optimum critical exponents appear to vary little from substance to substance. Moreover, a restricted version of the Linear Model with only two freely adjustable constants, in addition to the critical point parameters and the critical exponents, fits the data well in most cases, in agreement with expectations based on universality of critical behavior. The principle of universality is discussed and applied to predict critical region parameters for nine additional fluids, including several for which only limited experimental information is available. These additional fluids are Ar, Kr, N2, H2, CH4, C2H4, SF6, NH3and D2O. We thus conclude with a single universal equation for the critical region of all fifteen fluids considered in this paper.

ISSN:0047-2689    

DOI:10.1063/1.555529

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The microwave spectrum of acetaldehyde is critically reviewed and augmented through calculations which include the effects of internal rotation and centrifugal distortion. Since the primary objective of this review is to provide microwave spectral transitions applicable to radio astronomy studies, the review encompasses only the ground state rotational spectrum of the most abundant isotopic form of acetaldehyde,12CH312CH16O. While all measured transitions are included, the predicted transition frequencies were limited toJ?12 in the range of 900 MHz to 250 GHz. In addition to this spectral information, the review includes the rotational constants, centrifugal distortion constants, inertial rotation parameters, electric dipole moment, structural data, moments of inertia, and constants relating to the barrier to internal rotation.

ISSN:0047-2689    

DOI:10.1063/1.555530

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The available data on the microwave spectrum of isocyanic acid are critically reviewed for information applicable to radio astronomy. Molecular data such as rotational constants, centrifugal distortion parameters, dipole moments, hyperfine coupling constants, and structural parameters are tabulated. Detailed centrifugal distortion calculations have been carried out for all isotopic forms of this molecule, including DNCO. Transitions have been predicted for the parent molecule for the frequency range 160 MHz−300 GHz. All predicted transitions include error limits. The quoted uncertainties represent one standard deviation. A 95 percent confidence limit is obtained by using approximately twice the calculated standard deviation. Estimated error limits for the measured transitions are discussed. References are given for all data included.

ISSN:0047-2689    

DOI:10.1063/1.555531

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A survey, comparison, and critical analysis is presented of data compiled from the scientific literature concerning diffusion in copper alloy systems involving elements in Group VII (Co, Fe, Ni, Pd, Pt, Rh, Ru). Here the term ’’copper alloy system’’ is interpreted in the broadest sense. For example, the review of diffusion in the Cu‐M system reports all diffusion situations which involve both copper and element M. including diffusion of Cu in M or in any binary, ternary or multicomponent alloy containing M; diffusion of M in Cu or in any alloy containing Cu; and diffusion of any element in any alloy containing both Cu and M. Topics include volume diffusion, surface diffusion, grain boundary diffusion, tracer diffusion, alloy interdiffusion, electromigration, thermomigration, dislocation‐pipe diffusion, and diffusion in molten metals. An extensive bibliography is presented along with figures, tabular presentation of data and discussion of results.

ISSN:0047-2689    

DOI:10.1063/1.555528

出版商:AIP    

年代:1976

数据来源: AIP