Showing papers by "Technical University of Madrid published in 1977"
01 Nov 1977
TL;DR: In this article, a new equation for isothermal relaxation of stress-relieved steel was derived to study stress losses in prestressed elements due to steam curing of concrete, and a calculation method was proposed, which took into account the effect of loosening during heating and of releasing of the prestressing force.
Abstract: A new equation for isothermal relaxation of stress-relieved steel previously derived, has been modified to study stress losses in prestressed elements due to steam curing of concrete. A calculation method is proposed, which takes into account the effect of loosening during heating and of releasing of the prestressing force. The theory predicts a complete stress stabilization after steam curing up to times depending on temperature and duration of the steam curing. Furthermore, for longer periods the theory predicts an increase of the relaxation values. Tests performed show an excellent agreement between theory and experimental results.
3 citations
TL;DR: The effects of acute gamma irradiation on two models of phytocenoses (natural polyphytic grasslands and freshwater phytoplankton communities developed in artificial cultures) have been studied.
1 citations
01 Jan 1977
TL;DR: In this article, the stability of the equilibrium state was investigated by investigating the location of the roots of the quasicharacteristic equation. But the authors assume that the car following the leader is in an equilibrium state when there is no speed differential with the leading car and when it follows it at the safe minimum distance.
Abstract: of the distance between the cars and of the speed difference. We assume that the car following the leader is in an equilibrium state when there is no speed differential with the leading car, and when it follows it at the safe minimum distance. Taking into account the driver’s reaction time, the resulting model is a functional differential equation. We study the stability of the equilibrium state by investigating the location of the roots of the quasicharacteristic equation. We carry out both numerical and graphical simulations, and use a continuation method to get the variation of these roots as the parameters change whithin some ranges of values. This gives us regions of values of the parameters for which the equilibrium solution changes its stability giving rise, eventually, to some kind of periodic solutions.