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.

An investigation, by the method of characteristics, of the lateral expansion of the gases behind a detonating slab of explosive

Abstract: The phenomena occurring when an uncased explosive charge is detonated in a fluid medium are examined by hydrodynamical methods. Attention is focused chiefly on the pressure and velocity distributions in the gaseous products of the explosion, which expand laterally behind the detonation wave as it travels down the charge, the results being shown in graphical form. To simplify the problem, the charge, and the gas and fluid fields, were treated as two-dimensional. The hydrodynamical equations were solved numerically using the method of characteristics. This dates back to Monge, but it is only recently that it has been applied to the numerical solution of hyperbolic equations. The methods of numerical integration used in this paper are similar to those developed early in the war by the Research Section of the External Ballistics Department, Ordnance Board, for determining the velocity distributions around projectiles moving at supersonic speeds. The nature of the boundary conditions made it necessary to find explicit theoretical formulae for the gas field near the charge, and the analysis involved is given at length. For the problem in which the surrounding medium is air, the shape and position of the shock waves set up by the explosion are calculated. The shock waves are found to be straight to the nominal accuracy of the calculations (1 in 5000) for six charge widths from their intersections with the block of explosive.

The Initial Behaviour of a Spherical Explosion. I. Theoretical Analysis

Abstract: The analysis of the disturbance near the source of spherical blast from a polytropic explosive in which $\gamma $ = 3, given in Berry & Holt (1954), is generalized to apply to an explosive gas and a surrounding medium governed by any equations of state. Most of the properties established in the special case are found to be generally true. In particular, a second blast wave is shown to be a consequence of the breakdown of continuous gas flow in the neighbourhood of a singular characteristic. The complete field near the origin of blast can be determined from series expansions similar in type to those in Berry & Holt (1954). Except in the gas expansion zone the coefficients in these expansions can be expressed in simple terms. The quantity defining the first departure of the second shock from the singular characteristic is given by an expression as simple as that in the polytropic case, although its derivation presents new difficulties. The analysis shows that, for all types of explosive, the second shock is a second-order effect in terms of the square root of the time from the end of detonation. This contradicts that conclusion reached earlier by Wecken (1951) on the basis of less detailed analysis. Application to actual explosions is described in the second part of this paper.

The Effect of a Periodic Variation in the Field Intensity Across a Radiating Aperture

Abstract: Periodic variations in the field intensity across a radiating aperture are investigated, and it is shown that they may alter the shape of the radiation pattern and reduce the power gain of the aperture. The way in which such variations arise in the distribution existing across the outer surface of a microwave lens is discussed.

The liberation of cell-bound vaccinia virus by ultrasonic vibration.

Abstract: A true estimate of the virus content of infected tissues will only be obtained if all the complete virus particles are released from the cells and suspended without inactivation as individual infectious units. This is particularly important in the early stages of a growth cycle when an eclipse phase may be present. When the infected cells are present in the form of tissues or pieces of tissue only crude methods of cell disintegration are available such as grinding with abrasives or homogenizing in a blendor. Standard blendors produce very little cell breakdown, and Anderson (1954) has shown that some methods of grinding cause considerable reductions in the infectivity of vaccinia and other virus suspensions. With tissue-culture material more elegant techniques are applicable for the release of virus, and the increasing importance of tissue culture for the intimate study of virus multiplication and for the large-scale production of virus suspensions make a detailed investigation of such methods desirable. In this communication comparisons of several methods of liberating vaccinia virus from suspensions of infected HeLa cells are presented and the high efficiency of ultrasonic vibration for this purpose is clearly demonstrated. Virus suspensions obtained by this method are probably close to the ideal yield of infectious units from these cells.