Coefficient of thermal diffusivity of ChS-139 steel in wide temperature range

Laser flash method with 2–4% accuracy was used to determine the coefficient of thermal diffusivity of ferrite-martensite steel ChS-139 in temperature range 296–1274 K. Temperatures of Curie and martensite-austenite-martensite phase changes have been determined.     

Density of liquid and solid Mg-Pb alloys

Experimental data on the thermal properties of Mg-Pb alloys in solid and liquid states are generalized and analyzed. The temperature and composition dependences of molar volume and volumetric thermal expansion coefficient of the magnesium-lead system are constructed and discussed. The phase diagram of the system is refined.     

Hypersonic multicycle gas jet with a high degree of underexpansion at the nozzle exit

Experimental research on highly underexpanded gas jets flowing from supersonic nozzles into an ambient medium has shown that for fairly large Mach and Reynolds numbers at the nozzle exit the jet consists of several cycles or barrels [1–3]. The authors have made a theoretical study of these jets, using the nonstationary analogy method (law of plane sections). An approximate model of the flow is constructed and an analytic solution is obtained for the location of the boundary of the multicycle jet. The corresponding equivalent nonstationary problem of the expansion of a cylindrical slug of gas is solved numerically. The results are found to be consistent with the experimental data and make it possible to explain a number of observations. It is shown, for example, that the experimentally observed decrease in the amplitude of the cycles (maximum radius of the barrels) as they progress downstream is due to the dissipation of energy in shock waves. It appears that the length of the cycles is more or less independent of the dissipation and almost constant. The effect of the removal (supply) of heat, for example, due to radiation, the relaxation of internal degrees of freedom, etc., on the geometry of the jet is examined. It is shown that the removal of heat leads to a decrease in the amplitude of the cycles and the supply of heat to an increase, but, like dissipation, neither affects the length of the cycles. The problem of a jet in a weakly inhomogeneous atmosphere is solved. It has shown that the jet geometry possesses an adiabatic invariant linking the length and amplitude of the cycles.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 27–35, November–December, 1984.     

A limit theorem with weights for quadratic Dirichlet L-functions

Translated from Matematicheskie Zametki, Vol. 55, No. 2, pp. 128–129, February, 1994.     

Mean value of Dirichlet L-functions in the critical strip

Vilnius University. Translated from Litovskii Matematicheskii Sbornik (Lietuvos Matematikos Rinkinys), Vol. 31, No. 4, pp. 678–686, October–December, 1991.     

Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions

Time‐resolved pump–probe gas‐phase X‐ray scattering signals, extrapolated to zero momentum transfer, provide a measure of the number of electrons in a system, an effect that arises from the coherent addition of elastic scattering from the electrons. This allows to identify reactive transients and determine the chemical reaction kinetics without the need for extensive scattering simulations or complicated inversion of scattering data. We examine the photodissociation reaction of trimethylamine and identify two reaction paths upon excitation to the 3p state at 200 nm: a fast dissociation path out of the 3p state to the dimethyl amine radical (16.6±1.2 %) and a slower dissociation via internal conversion to the 3s state (83.4±1.2 %). The time constants for the two reactions are 640±130 fs and 74±6 ps, respectively. Additionally, it is found that the transient dimethyl amine radical has a N?C bond length of 1.45±0.02 Å and a C?N?C bond angle of 118°±4°.     

Thermal conductivity of liquid rubidium in the interval of 312–873 K

The thermal conductivity λ and the thermal diffusivity a of liquid rubidium were measured by the laser flash method in the temperature interval from the melting point up to 873 K. The measurement error was 4–6%. The data of this paper were compared with the results of other authors. Approximation equations and the table of reference values for the temperature dependence of λ and a have been obtained. The dependence of the Lorentz number on temperature has been calculated.