Patent GB-925589-A (GB)
Title: Improvements in or relating to analogue computers
Inventor: EMMS EDWARD THOMAS
IPC: G06G7/24
Filed: 1958-05-20
Abstract: 925,589. Electric analogue calculating. GENERAL PRECISION SYSTEMS Ltd. May 20, 1959 [May 20, 1958], No. 16235/58. Class 37. For simulating a dynamic system or process that involves a variable whose instantaneous rate of change is dependent on its own instantaneous value in that it increases with increase in such instantaneous value; an electromechanical analogue computer comprising computer means following a mathematical equation relating the variable to the rate of change of a logarithmic function thereof, instead of to the rate of change of the variable itself; thereby raising to a higher order the range of simulated system or process change to which the computer can continuously respond, as compared with a computer obeying the equation presenting the variable and its rate of change in direct form. For simulation of the operation of a nuclear reactor according to the reactor kinetic equations reduced to the form wherein n = neutron flux at time t (proportional to available power); to = mean neutron life; k = reproduction factor; # = proportion of total neutrons which are delayed; r i  = number of delayed neutrons in a group i (=1, 2, 3, 4 &c.) ; # i  = decay factor of delayed neutrons of i group Á i  = fraction of delayed neutrons in group i; s = term due to spontaneous fission; Y i  = r i /n; an electric analogue computer (Fig. 1) comprises an integrating servomotor energized by a signal d (log n) from summing amplifier 13 receiving dt 1 signals representing - over scaling resistance to (1- b)k 14, over scaling resistance 15 from poto tentiometer 16, positioned by the k servo simulator (not shown), ##iyi over sealing resistances 17 to 22 representing y i  from sources of voltage representing, e.g., y 1  to y 6 , and   s/n from antilogue potentiometer 24 over 1/n scaling resistance 23. The servomotor 11 adjusts shaft 12 and potentiometer 24, and other output potentiometers, e.g. 25, 26, feeding simulated power indicators to angular positions representing log n, and a follow-up servomotor 27 fed from amplifier 13 positions shaft 28 to d log n represent and to correspondingly adjust dt potentiometers 29 to 34 which produce six voltages Y 1  to y 6  of the form Respective computing circuits of the kind shown in Fig. 2 each comprise an electronic capacitance resistance integrator 36 receiving the appropriate potentiometer output together with a signal Á i #k/to from potentiometer 39 driven by the R servo over scaling resistance 38; and a signal yi#i over a scaling resistance from the integrator output. The appropriate potentiometer 29 is energized in anti-phase at opposite ends by means of inverting amplifier 37. Equation (4) is satisfied; and the integrator output represents y i  for energization of the corresponding scaling resistor 17 to 22. The apparatus of Fig. 1 then satisfies equation (5) so that the output potentiometers 25, 26 of antilogue characteristics produce outputs proportional to neutron flux n or available power. The circuit of Fig. 2 is repeated once for each of the values Y 1  to y 6  required for different values of i according to equation (4).