Abstract: An apparatus for evaluating dielectrically-anisotropic materials including a plurality of microwave transmitters with differing planes of polarization, and a plurality of microwave receivers with differing planes of polarization, wherein each transmitter includes a device for modulating the microwave beam to be transmitted, the transmitters and receivers arranged, relative to a workplace to be measured, so as to cooperate in communication therebetween, and wherein connected to each receiver is a processor to identify the received amplitude and phase of a component of the transmitted microwave beam, and to analyze by Fourier analysis the received signals to identify the principal axes, attenuations and phase shifts of the received microwave beam without requiring the phases of the transmitted microwave beams to be synchronized.

Abstract: An apparatus for evaluating dialectically-anisotropic materials comprising a plurality of microwave transmitters with differing planes of polarization, and a plurality of microwave receivers with differing planes of polarization, wherein each transmitter includes a means of modulating the microwave beam to be transmitted, the transmitters and receivers arranged, relative to a workpiece to be measured, so as to cooperate in communication therebetween, and wherein connected to each receiver is a processor to identify the received amplitude and phase of a component of the transmitted microwave beam, and to analyze by Fourier analysis the received signals to identify the principal axes, attenuations and phase shifts of the received microwave beam without requiring the phases of the transmitted microwave beams to be synchronized.

Abstract: This invention provides an improved method for estimating the strength or stiffness of a piece of wood by measuring the longitudinal density profile of the wood. The density profile of the wood is determined by measuring the absorption or other modification of radiation at a sequence of local areas in the wood. The strength or stiffness estimation method identifies and quantifies those features in the wood density profile which describe two of the main wood factors that control overall wood strength or stiffness, i.e. the inherent (clear) wood strength or stiffness and the wood structural effect. The inherent wood strength or stiffness is mainly identified by the areas relatively constant density between knots, and the wood structural effect is mainly identified by the sharp density increases caused by knots. The strength or stiffness estimate for the wood combines these two factors.

Abstract: A glass for sealing a beta-alumina tube in a sodium-sulphur cell has a composition suitable to resist attack by sodium at elevated temperatures and a coefficient of thermal expansion suitable for use with beta-alumina. The glass consists essentially of 28-48 mol % B.sub.2 O.sub.3, 0-20 mol % SiO.sub.2, 16-28 mol % Al.sub.2 O.sub.3, together with 18-33 mol % of at least one alkaline earth oxide selected from the group consisting of BaO, SrO, CaO and MgO, the proportions of the constituents being such that the combined total of B.sub.2 O.sub.3 and SiO.sub.2 is 40 to 60 mol % and furthermore being such that 0.0517 A.sub.1 +0.0354 A.sub.2 -0.0063 A.sub.3 +0.168 A.sub.4 +0.1336 A.sub.5 +0.098 A.sub.6 +0.1597 A.sub.7, lies between 5.7 and 6.4 where A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5, A.sub.6 and A.sub.7 are the respective molar percentages of B.sub.2 O.sub.3, SiO.sub.2, Al.sub.2 O.sub.3, BaO, CaO, MgO and SrO.A cell sealed with such a glass is described.