Axisymmetric vibrations of polar orthotropic mindlin annular plates of variable thickness

Analysis and numerical results are presented for the axisymmetric vibrations of polar orthotropic annular plates with linear variation in thickness, according to Mindlin's shear theory of plates. A chebyshev collocation technique has been employed to obtain the frequency equations for the transverse motion of such plates, for three different boundary conditions. Frequencies, mode shapes and moments for the first three modes of vibration have been computed for different plate parameters. A comparison of frequencies with the corresponding values obtained by classical plate theory leads to some interesting conclusions.     

The measurement of tritium activity in natural waters

Proceedings - Mathematical Sciences - To exploit natural and artificial activity of tritium, H3 (half-life, 12.3 y.), as a tracer for the study of the large-scale circulation of air in the...     

Effect of an elastic foundation on axisymmetric vibrations of polar orthotropic annular plates of variable thickness

Free axisymmetric vibrations of a polar orthotropic annular plate of linearly varying thickness resting on an elastic foundation of Winkler type are studied on the basis of classical theory of plates. The fourth order linear differential equation with variable coefficients governing the motion is solved by using the quintic spline interpolation technique for three different combinations of boundary conditions. The effect of the elastic foundation together with the orthotropy on the natural frequencies of vibration is illustrated for different values of the radii ratio and the thickness variation parameter for the first three modes of vibration. Transverse displacements and moments are presented for a specified plate. The validity of the spline technique is demonstrated by presenting a comparison of present results with those available in the literature.     

Fluorescence and lifetime studies of Ho3+: CaF2

Four fluorescence groups in the wavelength region 4775–7590 Å have been recorded in Ho³⁺: CaF₂ single crystals in the concentration range from 0.01 to 0.1 wt% of Ho³⁺. The observed variation of the relative intensities of various fluorescence lines with concentration indicate the presence of more than one Ho³⁺ site in CaF₂. This has been further substantiated by the observation of three different fluorescent decay times. The increase in the fluorescent decay times with concentration above 373 K is explained as probably being due to reabsorption of fluorescence radiation.     

Cylindrical wave solutions of a scalar-tensor theory

Summary Recently Dunn(1974) has formulated a scalar-tensor theory of gavitation and proposed a set of field equations, by taking a modification of the Riemannian geometry and has obtained static spherically symmetric solutions of the vacuum field equations. In this paper we have investigated the cylindrical wave solutions of the above mentioned field equations in a space-time with a metric which is more general than that of Einstein-Rosen. It has been shown that these solutions can be deduced from the known solutions of the field equations representing empty space-time taken along with the Einstein-Rosen metric. Lastly some plane-wave solutions corresponding to the Bondi's general plane-wave metric, have come under inverstigation as a direct consequence of a certain assumption. Entrata in Redazione il 10 aprile 1976.     

On the magnetic susceptibility of samarium and europium molybdates and tungstates

Measurement of molar magnetic susceptibility of [α-Eu₂(WO₄)₃] type samarium and europium molybdates and tungstates are reported in the temperature range (5–300 K) at an applied magnetic field of 1.2×10⁶Am^-1. The results have been explained taking crystal field effect and exchange forces.     

Development of a novel composite by coating polyacrylic fibres with hexacyanoferrates for the removal of Cs from radioactive liquid waste

Hexacyanoferrates (HCFs) are known to be efficient sorbents for the removal of Cs from aqueous solutions. But the powdery precipitate of HCF is unsuitable for use in columns. To make it amenable to column application, it has been coated on polyacrylic fibres by in situ precipitation. In batch and column experiments, the fibres coated with Cupric ferric hexacyanoferrate provided good removal of¹³⁷Cs from radioactive effluents. Leaching of Cs from the fibres was found to be only 14% in demineralised water medium. The Cs-loaded fibres could easily be incinerated to a smaller volume for further conditioning.     

Kinetics and mechanism of the oxidation of α-amino acids by n-bromoacetamide

The kinetics of the oxidation of eight α-amino adds by N-bromoacltanude have been studied in aqueous perchloric acid solution. The main products of the oxidation are the corresponding carbonyl compounds. The reaction is of first order with respect to the oxidant and the amino acid. The rate of oxidation decreases linearly with an increase in hydrogen ion concentration. The rate is decreased by the addition of acetamide. The oxidation of deuteriated glycine indicated the absence of a primary kinetic isotope effect. The reaction rate has been determined at different temperatures and activation parameters have been calculated. Hypobromous add has been postulated as the reactive oxidizing species. A rate-determining reaction of the neutral amino add and hypobromous add to give an N-bromo derivative has been proposed. The slow step is followed by a fast decomposition of the N-bromo derivative to yield the ultimate product.     

On the asymptotic theory of rank order tests for experiments involving paired comparisons

Summary The problem of testing the hypothesis of no difference among several treatments for the case when the comparisons between the treatments is possible only in pairs has been considered by Durbin [3], Bradley and Terry [1], Elteren and Noether [4], and Mehra and Puri [6], among others. Following the lines of Sen and Puri [9], a new approach to the asymptotic theory of rank order tests for this problem is developed. This avoids the unnecessarily complicated and lengthy conditional approach of Mehra and Puri [6] and also simplifies the proofs considerably. Prepared under contract Nonr-285 (38) with the Office of Naval Research, and Research Grant GM-12868 with the National Institutes of Health, Public Health Service.