National Physical Laboratory

About: National Physical Laboratory is a facility organization based out in London, United Kingdom. It is known for research contribution in the topics: Dielectric & Thin film. The organization has 7615 authors who have published 13327 publications receiving 319381 citations.

The Influence of Structure on the Physico-chemical Properties of Slags.

Abstract: The current knowledge of the structures of silicate slags is summarised and the relationships between measures of the depolymerisation of the melt and various physical properties are examined. It is shown that the optical basicity when corrected for the cations required to charge-balance any AlO45- tetrahedra present, provides a reasonable measure of the depolymerisation of the melt and has the advantage over the (NBO/T) ratio that it compensates for cation effects. It is shown that the depolymerisation of the melt is the primary factor affecting most physical properties, the cations having only a secondary effect. The relationships between structure and the viscosity, electrical and thermal conductivity, diffusion coefficient, density, thermal expansion coefficient, thermodynamic and optical properties of melts are discussed.

The physical properties of composite materials

Abstract: In this review, the physical properties of composite materials are discussed; however, discussion of the mechanical properties has been excluded except when necessary for the consideration of properties such as thermal expansion or swelling and shrinkage. One of the main aims in the review has been to show how the theoretical and experimental information that is already available may be used (a) to design and construct composite materials with predetermined physical properties and (b) to ensure that the physical properties of composite materials are properly measured and properly defined.

Recording of In-plane Surface Displacement by Double-exposure Speckle Photography

Abstract: Local displacements in the plane of an object surface illuminated by coherent light may be measured by recording double-exposure photographs of it. When the surface is illuminated symmetrically by two oblique beams, ‘speckle correlation fringes’ appear in the doubly exposed negative, due to the non-linear nature of the photographic recording. Factors affecting the visibility of these fringes and the range of displacement which can be measured are discussed. The fringe visibility falls to zero for displacements larger than a speckle width, but measurements can then be performed upon the optical transform of the negative image. With uni-directional object illumination, the in-plane displacement can be measured on a point-by-point basis in magnitude and in direction from Young's fringes observed. With two symmetrical oblique illuminating beams the effect of a small surface strain is displayed, even if large lateral displacement has occurred, by using spatial filtering when viewing the photographic image.

Low voltage analog circuit design techniques

Abstract: Analog signal processing is fast and can address real world problems. The applications of battery powered analog and mixed mode electronic devices require designing analog circuits to operate at low voltage levels. In this paper, some of the issues facing analog designers in implementing low voltage circuits are discussed, and possible low voltage design techniques are examined. The authors describe briefly almost all low voltage design techniques suitable for analog circuit structures along with their merits and demerits.