Abstract: Excellent likeness of impulse response function r.sub.o (t) of a given linear space is obtained by exciting the space through a transmitting transducer with a compressible probing signal x(t) which is a string of lowpass narrow p(t)-wavelets polarity-controlled by a single cycle of an m-sequence and processing received raw-data by cross-correlating it with a special reference s(t) which is cyclical repetition of the same m-sequence. Cross-correlating x(t) directly with s(t) yields compressed version of x(t) (denoted e(t)) which is p(t) multiplied by length of the m-sequence. e(t) equivalently excites the space to give processed output which is the likeness of r.sub.o (t). e(t) is free from side-lobes and readily made arbitrarily slim by choosing p(t) slim; keeping duration and energy of x(t) fixed, e(t) characterizes an area invariant of the slimness of e(t) or p(t).

Abstract: A torsion pendulum apparatus and a dialometer are combined for simultaneous measurement of the internal friction and the expansion of an alloy. The combination is controlled by a programmable controller so as to conduct in-situ measurements of the internal friction and the expansion of a metal during its phase transformation or specific heat treatment. The results of the internal friction measurement and the expansion measurement can be checked and assumed by one another so that more accurate and detailed information can be obtained for the study of metal alloys.

Abstract: A measuring apparatus is provided for measuring the internal friction of a transversely vibrating metal specimen at various operation temperatures. The measuring apparatus includes a container body mounted on a machine table and having an open upper end, an ascending device for moving vertically a container lid into and out of engagement with the container body, and a measuring unit secured to the lower surface of the container lid. The measuring unit includes a measuring rack, a heating body, a heating source, a temperature sensing element, a water-cooled driving member and a water-cooled detecting member. The specimen can be driven by the driving member to vibrate in the measuring unit and detected by the detecting member to allow determination of its metal properties.