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  1. Nonlinear Deflections of Shallow Spherical Shells

    Reiss, Edward L. ; Greenberg, Herbert J. ; Keller, Herbert B. - Journal of the Aeronautical Sciences
    The equations obtained by Chien for the nonlinear deflection of shallow spherical shells under uniform external pressure are solved by means of power series expansions following procedures introduced by Friedrichs and Stoker in their treatment of buckling of circular plates. These equations depend upon two parameters. One of these is related to the external pressure, while the other depends upon the dimensions of the shell. The equations are solved for several ranges of the parameters under boundary conditions corresponding to a fixed edge. The solution, carried out numerically on the Univac at New York University, yields a complete description ofmore » the stresses and deflections as functions of the polar angle over a wide range of values of the loading parameter and the dimensional parameter. Prediction of the upper buckling load is then made by means of a numerical criterion based on the load vs. deflection curve. For some cases, the post-buckling behavior is investigated. Finally, the results agree well with existing experimental and theoretical studies and cover a wide range of cases not previously treated.« less

  2. Pairing Effects in Coulomb Energies and the Radii of Mirror Nuclei

    Carlson, B. C. ; Talmi, I. - Physical Review
    The Coulomb energy difference between the nuclei of a mirror pair exhibits an odd-even alternation with Z that is presumed to reflect the well-known pairing property of the short-range nuclear forces. By taking second differences of Coulomb energy (differences between successive mirror pairs), the alternation is seen to continue to at least Z = 15, and additional irregularities appear that may be shell-structure effects. The analysis of Feenberg and Goertzel is discussed from the point of view of the shell model, and the pairing of spins is extended to the spherically symmetric pairing characteristic of the state of lowest seniority.more » A harmonic oscillator model with jj coupling is used to calculate the Coulomb energy, including exchange effects, in the state of lowest proton seniority. The single parameter of the model is determined by comparison with experimental data and remains constant to ±1.5 percent through the p$$\frac{1}{2}$$ and d$$\frac{5}{2}$$ shells. The rms radius of the nuclear charge distribution is calculated by the same model. Between C13 and Al27, the equivalent r0 decreases fairly smoothly from 1.34 to 1.20. For A ≤ 11 the model is not satisfactory, and for A ≥ 31 there are some serious inconsistencies in the data. Finally, the most recent data indicate that r0 may decrease to the range 1.1 to 1.15 for A≅39.« less

  3. Diffusion Coefficients for the System Biphenyl in Benzene

    Sandquist, C. Lennart ; Lyons, Philip A. - Journal of the American Chemical Society
    The diffusion coefficients, densities, viscosities and molar refractive increments for solutions of biphenyl in benzene have been determined at 25 and 35° in the concentration region 0-3 molar. Attention has been called to the significance of the overlapping of the plots of Dη/T against 5 at the two temperatures. A simple and useful deviation function has been pro-posed for the description of this type system. The activation energies for the viscous and diffusion processes have been compared. The suggestion has been made that the data, in particular at 25°, constitute reliable standards for calibration purposes.

  4. Elastic Scattering of Protons by Nuclei

    Chase, D. M. ; Rohrlich, F. - Physical Review
    Exact calculations are carried out for the optical model in the 20-Mev region. A complex potential of spherical well shape is assumed in addition to the Coulomb potential. Results for the elastic scattering of protons by Al, Cu, and Ag are compared with experiments. Though all relevant parameters are varied over large domains, no satisfactory agreement is obtained. Various possible alternatives are discussed. Finally, it is also shown that the "boundary condition model" offers a good approximation to the optical model within its range of validity.

  5. The interpretation of diffuse X-ray scattering from powder patterns of solid solutions

    Flinn, P. A. ; Averbach, B. L. ; Rudman, P. S. - Acta Crystallographica
    Methods are developed for the evaluation of the Fourier coefficients which measure the local order and the sizes of atoms in solid solution. A transform of the diffuse scattering from polycrystalline samples modified by an exponential weighting function is used to obtain these coefficients with a minimum of false detail. Two experimental examples are given. Measurements of the diffuse intensity in electron units from an aluminum-zinc alloy at 400°C show that zinc-rich clusters exist in the equilibrium solid solution above the solubility temperature. Similar measurements for a nickel-gold solid solution indicate a preference for unlike neighbors above the solubility gap.more » Finally, in the latter system the diffuse intensity produced by the difference in atomic radii is also observed.« less

  6. The Signs of the Phase Shifts for Pion-Proton Scattering

    Barnes, S. W. ; Angell, C. E. ; Perry, J. P. ; ... - Physical Review
    In principle, it is possible to determine the sign of the pion-proton nuclear interaction by measuring the effect of interference between the nuclear and Coulomb amplitudes in pion-proton scattering. The findings are discussed in this work.

  7. Acoustic Wave Velocities, Elastic Constants, and Debye Characteristic Temperature for Polycrystalline MgCd

    Smith, Charles S. ; Wallace, W. E. - Journal of Chemical Physics
    The longitudinal and transverse acoustic wave velocities in a polycrystalline magnesium-cadmium alloy containing 50.6 atomic per cent cadmium were measured using the pulsed ultrasonic method. The alloy was prepared by fusing together spectroscopically pure magnesium and cadmium under a blanket of helium purified by evaporation. Experimental details concerning preparation and analysis of the alloy and the method employed in measuring the sound velocities are given elsewhere.

  8. The Dipole Moment of Thioacetoacetic Ester in Solution1

    Ferraro, Charles F. ; Draney, John J. ; Cefola, Michael - Journal of the American Chemical Society
    Values of the apparent dipole moment of 2.2 to 2.4 D were observed for thioacetoacetic ester dissolved in benzene, n-hexane, carbon tetrachloride and carbon disulfide. Structural configurations have been assigned to the thioenol and thione tautomeric forms of the ester and their dipole moments calculated from reported bond and group moments. Finally, on the basis of the observed and calculated values, it is postulated that a trans-thione and a trans-thioenol tautomer with the latter exhibiting intramolecular rotation are the predominant configurations of the ester in solution.

  9. Studies on Coördination Compounds. I. A Method for Determining Thermodynamic Equilibrium Constants in Mixed Solvents1, 2

    Van Uitert, LeGrand G. ; Haas, Charles G. - Journal of the American Chemical Society
    In the past "pH" titrations in partially non-aqueous solvents have been made in order to determine the stability of coordination compounds. The interpretation of such data has been reconsidered with the object of obtaining thermodynamic stability constants. It is assumed that the activity coefficient of electrolytic solutes in these solvents is determined solely by the solvent composition and the ionic concentration. Finally, experimental substantiation of the assumption is given and the method of calculating thermodynamic stability constants is discussed.

  10. The Effect of a Low Absorption Coefficient on X-Ray Spectrometer Measurements

    Keating, D. T. ; Warren, B. E. - Review of Scientific Instruments
    In x-ray spectrometer measurements with a flat sample, low absorption produces an asymmetric broadening and displacement of the measured peak. The distortion of the peak due to low absorption can be corrected by an expression involving only the measured peak shape and its derivative. Finally, the distortion can also be corrected by the Stokes method of Fourier analysis, and values of the coefficients are given for a suitable range of experimental conditions.
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