Ministry of Supply

About: Ministry of Supply is a based out in . It is known for research contribution in the topics: Polarography & Bacillus (shape). The organization has 416 authors who have published 355 publications receiving 8951 citations. The organization is also known as: MoS.

The Theory of Wedge Indentation of Ductile Materials

Abstract: The theoretical solution for the deformation produced by a rigid frictionless wedge penetrating a plastic material is presented in this paper. The solution determines the form of the lip and the deformation in the material squeezed out towards the surface. The variation with wedge angle of the force required for penetration is determined in terms of the yield stress in a tensile test. The deformation of a grid of squares on a plane normal to the axis of the wedge is shown in figure 9 for a 30° semi-angle wedge. Close agreement is obtained with experiments as shown by comparing figure 9 with the photographs in figure 10 (plate 4). Lead blocks were used with a grid of squares scribed before penetration. This investigation is a first step towards the correlation of hardness test results with the deformation properties of a material under other conditions of stress, e.g. the tensile test. The average strain due to wedge indentation is shown to correspond to an equivalent reduction of area in a tensile test which increases with increasing wedge angle.

The Theoretical Precision with which an Arbitrary Radiation-Pattern may be Obtained from a Source of Finite Size

Abstract: It appears that it is possible to approximate as closely as desired to a specified radiation-pattern by a suitable distribution of field over an aperture of given size, though the necessary currents in the conducting elements of the source would in general be prohibitively large in comparison with the power radiated. The difficulty of obtaining a high degree of approximation, and in particular a power gain very much greater than that of a uniformly illuminated aperture, is thus a practical rather than a theoretical one. The same is true for the linear array of given length as for the continuous aperture if no limit is set to the number of elements. Even when this number is limited by the adoption of half-wavelength spacing, the broadside power gain is not a maximum when the amplitudes and phases of the elements are equal, unless the elements are ideal isotropic point-sources.