Abstract: A method for diagnosis of a defect of an object to be inspected, such as a rotational machine, etc., by measuring a vibration generated thereby, wherein a measured signal generated by the object is detected, an amplitude probability density function of wave-form of the obtained measured signal is expanded orthogonally through a Gram-Charlier series, and the Gram-Charlier series are calculated so as to make diagnosis of defect(s) in the object to be inspected.

Abstract: Ferrite having a uniform degree of oxidation is produced at a higher rate of ferrite forming reaction by pelletizing a mixture of iron oxide and ferromanganese powders and calcining the mixture at a temperature of 900.degree. C. or higher. Zinc oxide, magnesium oxide and/or nickel oxide may be further added to the mixture, as required.

Abstract: A method of detecting the shape of flat products, which comprises applying, through an exciter, to an examined objects in its width, exciting signal generated in an exciting signal generator, as an exciting force, concurrently detecting the deflection of said examined object taking place due to the application of such exciting force at a plurality of points on said examined object in the width direction, correlating the exciting signal and the so detected values of deflection in the signal processing circuit, and determining the tension of said examined object at respective points on said examined object. The tension distribution on said examined object, in the width direction can therefore by determined, whereby the shape of said examined object can be ascertained.