Showing papers in "Acta Astronautica in 1978"

TL;DR: In this paper, the authors studied the role of photo-chemical initiation in the formation of a detonation in gaseous mixtures of C 2 H 2 -O 2, H 2 O 2 and H 2 Cl 2 in the pressure range of 10 −150 torr using flash photolysis.

TL;DR: In situ production of rocket propellant to reduce landing mass requirements for Mars return missions has been investigated in this paper, where it was shown that a system which utilizes atmospheric carbon dioxide and soil moisture to produce liquid methane-oxygen propellant requires a landed mass which is less than half the mass of the ascent vehicle it produces.

TL;DR: An experimental verification of Marangoni convection in the liquid inter-space between two-coaxial discs is carried out at reduced gravity effect using small Bond's number obtained by choice of small characteristical diameter.

TL;DR: In this paper, it was shown that spherical detonations are self-sustained by continuous measurement of detonation velocity using X-band microwave interferometry, which indicates the existence of a dissociated phase in which shock and reaction fronts may no longer be coupled.

TL;DR: In this paper, a general formulation for librational dynamics of satellites with an arbitrary number, types, and orientation of deploying flexible appendages is presented, and the corresponding nonlinear, nonautonomous equations for in-plane and out-of-plane vibrations are derived, allowing for the variation of mass density and flexural rigidity along the length with time dependent deployment velocity and spin rate.

TL;DR: In this paper, the Nordtvedt effect was shown to be caused by planetary perturbations, general relativity, and the solar gravitational quadrupole moment (GQM), and a value of (2.5 ± 1.6) × 10 −6 is obtained for J 2.

TL;DR: In this paper, two different interatomic potentials have been used, one endothermic and one net-exothermic, to simulate flyer-plate impact on two-dimensional lattices.

TL;DR: In this article, it is suggested that the flow of the liquid in foam cells has to be taken into account in order to predict the behavior of shock waves in foams, and the nature of the gas which fills the cells is shown to have a strong effect on the quenching of blast waves in foam.

TL;DR: In this paper, a model for an elementary detonation cell is proposed and the geometry of the cell pattern and the kinematics of the wave fronts forming the cells are evaluated.

TL;DR: In this article, nonequilibrium chemical processes of nitric oxide formation were computed for the wake of the Tunguska meteor of 1908, and the wake characteristics were derived by carrying out an optically-thick radiation field analysis for ablation of the meteoroid.

TL;DR: In this article, the basic set of equations needed to completely describe the thermodynamics and dynamics of pure interfaces is derived, on a coherent postulatory basis, and a discussion of the interface balance equations considered as boundary conditions for the field equations pertaining to the adjoining bulk phases is given and the inadequacies of previous ad hoc formulations pointed out.

TL;DR: In this article, a numerical simulation approach is employed in which they use a one-dimensional (spherical symmetry), time-dependent computer model to simulate the coupled compressible fluid dynamics-chemical kinetics processes which occur upon direct initiation of detonation in unconfined, gaseous mixtures of methane/oxygen/nitrogen.

TL;DR: In this paper, the problem of numerical modeling of unsteady flame propagation with large amounts of exothermic heat release has been addressed through the use of a model equation which contains many of the important nonlinearities and difficulties in the problem.

TL;DR: In this article, an analysis of experiments which test the uniqueness of the ratio of inertial and passive gravitational mass has been made, which shows that an improvement in sensitivity of at least six orders of magnitude is possible in Earth orbit.

TL;DR: In this article, an ultralow magnetic field apparatus for earth-based testing of a cryogenic gyroscope system designed for a satellite test of general relativity is described, which makes use of a superconducting lead shield while also maintaining sufficient mechanical stability to obtain a gyroscopic readout sensitivity of one arcsec over a limited range.

TL;DR: In this article, the authors considered the problem of finding the equilibrium of a floating zone held between two discs in relative motion, and showed that the solution of the problem is difficult even assuming a constant property-newtonian liquid.

TL;DR: In this paper, the general equations of a sloshing fluid in a rigid container are written for Newtonian potential and the unknowns are reduced to an ordinary system via Galerkin's weighting technique.

TL;DR: In this paper, an experimental study of the turbulence generated by an enclosed, premixed, propane-air flame has been carried out in a combustion chamber of 25 × 20 cm cross section.

TL;DR: In this paper, a numerical model of chemically reactive flow in combustion systems is examined with a simulation of flames propagating through spatially uniform and stratified media, and results indicate that hydrodynamic factors can have a significant effect on the energy production rates, pressure rise rates, and unburned fuel concentrations for all models.

TL;DR: In this paper, the authors model the combustion of a turbulent homogeneous mixture of propane and air within a duct having a stationary one-dimensional mean flow and apply the Bray-Moss model to the closure of the chemical production terms.

TL;DR: In this article, a series of experiments were conducted using kerosene drops of 388 μm diameter dispersed in air through use of a large number of hypodermic needles, and preliminary results relating to the effect of the size of the cloud gap on detonation velocity, quenching, and initiator energy levels required for detonation were discussed.

TL;DR: The Hermes satellite as mentioned in this paper is a communications technology satellite that was launched by NASA on 17 Jan. 1976 as part of a joint U.S/Canadian program in which Canada designed, assembled and now operates the satellite.

TL;DR: In this paper, a method to improve rock fragmentation with explosives is proposed based on a new way of explosion energy transfer to the solid media, which provides a considerably higher efficiency of the explosion energy by changing the gas dynamic processes of the expansion of detonation products in the charge chamber.

TL;DR: In this article, two superconducting accelerometers have been developed as sensors for the gravity wave experiment, which consist of radio frequency resonant circuits whose parameters are modulated by acceleration.

TL;DR: In this article, the authors proposed a three-axis stabilized spacecraft design with sun-oriented solar panels, which provides maximum power and weight capability to the primary communications payload within the launch vehicle envelope.

TL;DR: In this paper, the authors considered the problem of estimating the probability of a triple system formation by a random meeting of two binary stars and gave a first order integrable approximation for any eccentricities and any inclinations.

TL;DR: In this paper, the theoretical sensitivity of a gravitational radiation antenna instrumented with a resonant capacitor transducer is considered. And an expression for the sensitivity limit resulting from the preamplifier noise is derived.

TL;DR: In this paper, the rate of amplification of a discontinuity in the slope of the field variables (velocity, pressure, etc.) at the head of a disturbance is evaluated for propagation through a homogeneous exploding atmosphere.

TL;DR: In this paper, the development of satellite communication is presented in the context of the evolution of electrical communication at large, the formulation of information theory, and the impact of space technology on communication.

TL;DR: In this paper, the authors compare the caracteristiques of the perturbation (amplitude, duree de la surpression τ+, celerite de propagation) produite par l'explosion (deflagration, detonation) des charges spheriques de melanges reactifs gazeux, dans l'air environnant.