Vibration characteristics of self-expanding stayed columns for use in space

The type of stayed column considered was developed by the ASTRO Research Corporation for NASA to evaluate, and is designed to be deployed in space after forming a light, compact package in the Space Shuttle. It consists of a core with three identical stay frames equally spaced around it. Each stay frame has a central compressed spoke which pretensions stays which radiate from its end to the core. Three pretensioned battens connect the ends of the spokes. NASA performed vibration tests on a model of such a column and compared their results with approximate theoretical predictions. The present paper gives exact theoretical results, including natural frequencies and mode types not given in the NASA results. A substitute column method is used to achieve economy and a much deeper understanding of the modes. Approximations which give even greater economy and convenience are evaluated. A proposed design is analyzed alongside the NASA model. The proposed design is better than the NASA model because recent developments were implemented in the design method, and also because it has a graphite epoxy core whereas the NASA model had an aluminium one, due to temporary availability problems.     

Bianchi VI0 electric type cosmological models in General Relativity with stiff fluid and heat conduction

The paper consists of some exact tilted solutions for a homogeneous Bianchi type VI₀ universe. The material distribution is taken to be a stiff fluid with heat conduction. The physical and kinematical parameters have also been calculated to discuss the models in detail.     

Application of density-functional perturbation theory to calculate nonlinear polarizabilities of helium-like systems

Density-based perturbation theory within the Hohenberg-Kohn (HK) formalism of density functional theory (DFT), developed recently by us, is employed to calculate hyperpolarizabilities of helium-like ions from their ground-state densities obtained from their respective Hylleraas wavefunctions. The only approximation made is that of the local density (LDA) for exchange and correlation. Use of densities — instead of wavefunctions — in density-based perturbation theory together with simple approximate energy functionals makes our calculations much simpler than those based on wavefunctions. They lead, however, to accurate results.     

Spherically symmetric solutions with heat flow in general relativity

Some new solutions of shear-free imperfect fluid spheres with heat flux in the radial direction are obtained. They have isotropic pressure and could be the generalizations of earlier solutions of Nariai and of Banerjee and Banerji for perfect fluid without dissipation.     

Stepwise formation of uranium(vi) complexes with sulphonated phenolic compounds

The metal complexes of uranium(VI) with disodiuM 2-naphthol-3,6-disulphonate and 7-amino-1-naphthol-3,6-disulphonic acid were studied by the established potentiometric techniques of Bjerrum and Irving and Rossotti. The step-wise protonation constants of the ligands and the step-wise stability constants of the uranyl complexes were deterMined in 0.1 M sodiuM perchlorate Media at 25°.