Abstract: An electrically-conductive composite fiber composed of an electrically-conductive polyamide layer (A) containing 15-50 wt % of electrically-conductive carbon black and which is three or more times exposed at the fiber surface and a protective polyamide layer (B) which covers no less than 60% of the periphery of the fiber cross section and accounts for 50-97 wt % of the total fiber weight, does not exhibit component separation during spinning, retains its good initial conductive performance for a long period of time, and exhibits good color fastness.

Abstract: A highly oriented, undrawn, conductive, composite filament is provided, which is white or colorless and has antistatic properties durable over a long period when clothing utilizing the fiber are actually put on and washed. The filament is a sheath-core composite filament comprising a sheath of a fiber-forming thermoplastic polymer (A) and a core of a composition (B) comprising a conductive material which comprises a conductive metal oxide and a thermoplastic polyamide, having a core resistance of not more than 9.times.10.sup.10 .OMEGA./cm.multidot.filament, the composite filament maintaining a critical elongation--an elongation reached in the course of extending a composite filament at which the core resistance exceeds 1.times.10.sup.11 .OMEGA./cm.multidot.filament at a D.C. voltage of 1 kV--of at least 5% and a shrinkage in hot water at 100.degree. C. of not higher than 20%.

Abstract: There is described a composite sheet includes a textile layer containing an electrically conductive fiber with an electric resistance of 10.sup.5 to 10.sup.9 ohms/cm as disposed at spaced intervals not exceeding 30 mm and a semiconductive layer with a surface resistivity of 10.sup.6 to 10.sup.10 ohms as disposed on the reverse side of the textile layer. This composite sheet releases the static electricity of the charged body on mutual contact and is therefore suitable for use as a car upholstery material and particularly as a seat covering material.

Abstract: For measuring the sizes of particles in the falling state, electromagnetic waves having different frequencies are transmitted from a transmitter/receiver onto the particles in the falling state and reflected electromagnetic waves having different frequencies reflected from the particles in the falling state are received by the transmitter/receiver. Data of the distribution of sizes of the particles and the average size of the particles are derived from the detected intensities of the received reflected electromagnetic waves.

Abstract: For measuring the sizes of particles in the falling state, electromagnetic waves having different frequencies are transmitted from a transmitter/receiver onto the particles in the falling state and reflected electromagnetic waves having different frequencies reflected from the particles in the falling state and received by the transmitter/receiver. Data of the distribution of sizes of the particles and the average size of the particles are derived from the detected intensities of the received reflected electromagnetic waves.