Analogue computation applied to the needs of atomic engineering

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Annales de l'Association internationale pour le Calcul analogique

N o 2 -- Avril 1961

EDITORIAL

ANALOGUE COMPUTATION APPLIED TO THE NEEDS OF ATOMIC ENGINEERING Nuclear Centers in all countries - - a n d even the most unassuming - - now have computation installations of varying potential but which are always very much in use. In these computation centers analogue computation installations are well represented and, as the case may be, they are or not connected with the same organization as the digital computation installations. Quite often analogue equipment comprises several hundred amplifiers, dozens of multipliers and many accessory installations, particularly one or multiple channel recorders, multidimensionals, etc. The success of analogue computation in the nuclear field is not a mystery. It is due to the existence of numerous dynamic problems, particularly for neutronic kinetics, neutronic power control, evolution of thermal exchanges in the reactor and, contingently, energetic utilization of the thermal power thus produced. In many cases, the equations are not linear. What is more, they are partial derivative equations. It is therefore necessary to adopt a m.ethod of approximation (general& a t~'ansition to finite differences) which t~'ansforms the equation into a system of differential equations. All this explains lhe importance of equipment necessa~7 ~o the solution of such problems. What seems to me even more important, is the development of more original problems, and of corresponding techniques 1o soh'e them, devel,opment imposed by needs specifically nuclear. First of all must be mentioned the problem of a.ttmmadc changes of scale. It is known that at the starting and stopping of reactors the neutronic power evoh,es over several <>. It is therefore necessary, either to consider directly log n in the place of n, or to establish a device for automatic changing of scale. In both cases the analogue method becomes competitive in precision with the digital method, while becoming much cheaper. Mr. Caillet, of the Commissariat ~ l'Energie atomique, carries out interesting comparisons in this field. However, when speaking of automatic changes, one approaches the field of the introduction of logical devices in the analogue circuDs. It is the optimization of dynamic systems, which has been investigated ve~7 fully by Mr. A. Feldbaum, at the Institute of Automation and Telemechanics in Moscow. Without setting from now on such complicated problems, the nuclear field gives us the possibility of making the maximum use of the equipment for automatic recording of coeffidents with which most installations are fitted. Particularly, it is not out of the question to consider the direct connection of mmlogue and digital installations, connection which wow]d especially allow the automatization of the computation of scales and coefficients and thereby t,o pass directly to physical equations with analogue diagrams.

Edi/o~'ia/

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A first step has been made in this direction at the C.C.R, of ISPRA where a progl'aln has been written for a digital machine which does this work of automatic recording. The possibility of sending the punched strip made by this machine directly into the analogue machine is being considered at the moment. It must therefore be foreseen that there will be an ever increasing connection between ~nalogue and digital equipment. Even better, it can be foresaid that in the preparation of this future, the centers of nuclear computation will be pioneer,s, as can be expected of them. P. ERAFFORT Che] du Centre de Traitement de l'Ip~]ormation Scienti]ique. .DirectioJ~ G~ngrale, Recherches et Ep~seig~ement EURATOM,