Abstract: In an electronic circuit being provided with a plurality of circuit elements and performing a specified function, a plurality of specific circuit elements related to a circuit performing the specified function out of the plurality of circuit elements are composed of circuit elements changing their element parameters according to values indicated by control signals. The electronic circuit is provided with a plurality of holding circuits for holding a plurality of control signals to be given to the plurality of specific circuit elements. The values of the plurality of control signals which these holding circuits hold are changed by external or internal apparatuses according to a probabilistic searching technique (for example genetic algorithms or simulated annealing algorithms) so that the function of the electronic circuit satisfies designated specifications.

Abstract: A magnetic field detecting circuit has a relaxation oscillator SQUID. An oscillator circuit includes a coil and a resistor connected together in series. The oscillator circuit produces an output signal having an oscillating frequency dependent on an applied DC bias current. A magnetic field input circuit is magnetically coupled with the coil of the oscillator circuit for applying a magnetic field. A Josephson device is connected in parallel with the oscillator circuit for converting the magnetic field to an electric signal for varying the oscillating frequency dependent on the magnetic field. The magnetic field is detected by detecting a variation of the oscillating frequency. The sensitivity of the magnetic field detecting circuit is improved by magnetically coupling an RF-SQUID with an input coil to form the magnetic field input circuit.

Abstract: Method of and apparatus for measuring a space distribution of spacings between point scatterers. An ultrasonic wave is applied to an ultrasonic scattering medium which is an aggregation of point scatterers. Ultrasonic waves, scattered from the medium, are converted into an electric signal. The shape of a power spectrum of the electric signal is determined. A fractal analysis is effected so as to determine a fractal dimension and self-similarity with respect to the power spectrum shape. A spatial distribution of a structural inhomogeneity of the scattering medium is measured in accordance with results of the fractal analysis.