Optimization of the Binder Formulation to Increase the Energetic Performance of Polynitrogen Oxidizers in Metal-Free Compositions

The dependence of the specific impulse of metal-free energetic compositions based on high-enthalpy organic oxidizers on the elemental content and enthalpy of formation of the oxidizer and the nature and volume content of the composite binder consisting of hydrocarbon and active components has been studied. At a given volume content of the binder, the specific impulse of compositions based on oxidizers with an oxygen saturation coefficient of 0.6–1.3 can be increased by finding the optimal mass ratio of the hydrocarbon and active components in the binder. The optimal content of the hydrocarbon component increases from 0 to 100% as the oxygen ratio of the oxidizer increases from 0.6 to 1.3.     

On the capacity of Rayleigh fading cooperative systems under adaptive transmission

In this letter, the use of adaptive source transmission with amplify-and-forward relaying is proposed. Three different adaptive techniques are considered: (i) optimal simultaneous power and rate adaptation; (ii) constant power with optimal rate adaptation; (iii) channel inversion with fixed rate. The capacity upper bounds of these adaptive protocols are derived for the amplify-and-forward cooperative system over both independent and identically distributed (i.i.d.) Rayleigh fading and non-i.i.d. Rayleigh fading environments. The capacity analysis is based on an upper bound on the effective received signal-to-noise ratio (SNR). The tightness of the upper bound is validated by the use of a lower bound and by Monte Carlo simulation. It is shown that at high SNR the optimal simultaneous power and rate adaptation and the optimal rate adaptation with constant power provide roughly the same capacity. Channel inversion is shown to suffer from a deterioration in capacity relative to the other adaptive techniques.     

Effect of fillers on the supermolecular structure and properties of polyformaldehyde

The authors studied the effect of fillers (silica and aluminum silicate) of various particle size and shape on the supermolecular structure, hardness, wear resistance, and compressive strength of polyformaldehyde (PFA). It was found that these properties are improved only by small filler additions; at higher filler concentrations the mechanical properties of PFA deteriorate and a change takes place in the character of wear of this material.