Showing papers by "Ministry of Supply published in 1949"
TL;DR: In this paper, the structure of one-dimensional flames is determined by constants such as those of heat conductivity, of diffusion, and of the homogeneous reaction rates, and three simple cases are solved fully by a mathematical method of successive approximations.
Abstract: The structure of one-dimensional flames is shown to be completely determined by constants such as those of heat conductivity, of diffusion, and of the homogeneous reaction rates. The mathematical problem in the most general case is intractable, but three simple cases are solved fully by a mathematical method of successive approximations. The three cases are those in which diffusion is neglected compared with heat conductivity and in which reaction velocities of the following types are considered: unimolecular, bimolecular, and the quasibimolecular form of a unimolecular reaction at low pressures. The method of mathematical approximation is shown to involve errors of the order of only 10% in some actual cases, an error which is negligible compared with other uncertainties of the problem. In these simple cases it is possible to solve all details of the structure such as the variation of composition and temperature through the flame.
43 citations
01 Oct 1949
TL;DR: In this paper, an analysis of the effect of irregularities in the amplitude of pulses and jitter in the repetition rate on the energy-spectrum of a succession of pulses is presented.
Abstract: An analysis is presented of the effect of (i) irregularities in the amplitude of pulses, and (ii) jitter in the repetition rate on the energy-spectrum of a succession of pulses. In both cases the spectrum bas two components: (a) a line spectrum, and (b) a continuous spectrum. In case (i), the envelope of both spectra is proportional to the envelope of the energy-spectrum of a single pulse and the lines in the line spectrum are spaced by the repetition frequency (see Figs. 1 and 2). In case (ii), the envelopes of the spectra are not the same as the envelope of a single pulse, and the lines are spaced by the mean repetition frequency (see Figs. 3 and 4).
27 citations
TL;DR: In this paper, the general equations of a single-reaction flame are written down, allowing for the diffusion of the main reactants and products, and a method of successive approximation is applied to the equations with diffusion, giving an easily applied solution for the speed of a flame maintained by a single reaction whose rate depends only on the temperature and the concentrations of the reactants.
Abstract: The general equations of a single-reaction flame are written down, allowing for the diffusion of the main reactants and products. It is shown that the pressure-dependence of the flame speed is not altered by the consideration of diffusion. A method of successive approximation is applied to the equations with diffusion, giving an easily applied solution for the speed of a flame maintained by a single reaction whose rate depends only on the temperature and the concentrations of the reactants.
26 citations
17 citations
TL;DR: In the determination of metallic traces, insufficient attention has been paid either to the advantages of direct spectrography of chromatographic columns, or to the chromatic behaviour of organic metal complexes, although in the latter sphere the use of oxine1 and of violuric acid2 has been reported as discussed by the authors.
Abstract: IN the determination of metallic traces, insufficient attention has been paid either to the advantages of direct spectrography of chromatographic columns, or to the chromatographic behaviour of organic metal complexes, although in the latter sphere the use of oxine1 and of violuric acid2 has been reported.
13 citations
TL;DR: This preliminary note summarizes briefly some of the main results obtained to date, which are to be reported in full elsewhere.
Abstract: A FUNDAMENTAL investigation is in progress at the National Gas Turbine Establishment of the mechanism of the combustion of droplets in a fuel spray In particular, the factors influencing the rate of burning, that is, the rate of evaporation of the burning drops, are being investigated This preliminary note summarizes briefly some of the main results obtained to date, which are to be reported in full elsewhere
12 citations
TL;DR: In this article, it has been deduced that divalent manganese is only slowly oxidized by periodate unless a catalyst (such as the surfacc of metallic platinum) is present.
12 citations
TL;DR: In this article, a brief account of the analytical application of the distillation from IoM sulphuric acid is given, along with a brief description of the permanganate distillation process.
7 citations
TL;DR: Insecticidal smoke generators tested in the laboratory and in practice reduced heavy cockroach infestations to negligible proportions for 2–3 months, and there was evidence of some repellent effect.
Abstract: Insecticidal smoke generators were tested in the laboratory and in practice. Each generator contained 110–120 g. of crude insecticide, either D.D.T. or benzene hexachloride. Over half the insecticide was evolved unchanged as a smoke of particles less than 1 μ in diameter, by a slow combustion mixture. In the laboratory tests, the generators were used at the rate of one to 1800–2500 cu.ft. (50–70 cu.m.). Benzene hexachloride had a greater initial insecticidal effect and a better residual action up to a week after treatment; thereafter (1 and 6 months) the D.D.T. was more effective. The residual effects of horizontal surfaces were good against bedbugs, but the deposits on vertical surfaces were not highly efficient. Residual action against mosquitoes of vertical surfaces a week after treatment was fair, but effects of inverted surfaces were poor.
The deposits of active insecticide on horizontal surfaces were about 15–30 mg./sq.ft.; on vertical surfaces, 3–10 mg./sq.ft.; and on inverted surfaces, 2–6 mg./sq.ft.
A field trial was conducted between August and November in kitchens infested by flies and cockroaches. The generators were used at the rate of one per 64 cu.ft. (18 cu.m.). A substantial reduction of flies for 11 weeks was obtained by D.D.T., but for only 2 weeks with benzene hexachloride. Both treatments reduced heavy cockroach infestations to negligible proportions for 2–3 months. There was evidence of some repellent effect.
Thermal generators require careful precautions to prevent indirect tainting of food or beverages. They are very wasteful of insecticide especially since two or perhaps three treatments per season might be necessary. This would use twenty times as much insecticide as a spray treatment. On the other hand, labour and equipment costs are somewhat lower, and ease of operation very much greater, with smoke generators.
5 citations
TL;DR: In this paper, four methods of recording the transient optical phenomena associated with the spark breakdown of gases are described, and the consequent problems, limitations and characteristics of the methods are discussed, so that their application to the recording of similar optical phenomena may be appreciated.
Abstract: Four methods of recording the transient optical phenomena associated with the spark breakdown of gases are described in the paper. The duration of such transients may vary between the limits 10−3 sec down to 10−8 sec. The consequent problems, limitations and characteristics of the methods are discussed, so that their application to the recording of similar optical phenomena may be appreciated.The first two methods of recording are direct photographic techniques which make use of the Kerr cell and the rotating-mirror camera respectively. The third method described is an indirect one, in which a photo-multiplier tube is used to convert the optical transient to an electrical one; the latter is then displayed on the screen of a high-speed oscillograph and photographed. This method makes use of a sealed off cathode-ray tube which has a 9-cm screen and is operated from a 10-kV supply. The design of the oscillograph and the associated photo-multiplier and amplifier circuits are described and oscillograms are included to illustrate the performance of the equipment. In the latter part of the paper, a recording technique is considered, which is based on the application of television techniques to this work. The principles of the method, which makes use of an iconoscope type of tube, are stated.
4 citations
01 Apr 1949
TL;DR: During the war radar synthetic training devices were used to a great extent by the Royal Air Force for training operators, navigators, controllers, etc., in radar techniques, but the urgent necessity for training devices declined and comparatively few trainers are being designed at the present time.
Abstract: During the war radar synthetic training devices were used to a great extent by the Royal Air Force for training operators, navigators, controllers, etc., in radar techniques. As each new radar device was introduced (CHL, GCI, AI, Gee, H2S, Oboe, etc.) a simple synthetic trainer was designed concurrently with the design of the radar equipment. As operational experience was gained on the equipment a more complex crew trainer was designed. This type of trainer provided accurate presentation of a moving synthetic target or targets and complete operational ?practice?, with a record of the trainee's errors. Approximately 70 different types of trainers were developed for the various ?marks? of radar systems, varying in scope from the provision of simple synthetic echoes to a complex device such as the reproduction on the ground of a complete A.I. night-fighter interception. A brief description is given of the major types of trainers. The fundamental principles necessary for the control of synthetic targets in two and three dimensions are discussed. With the end of the war the urgent necessity for training devices declined and comparatively few trainers are being designed at the present time.
01 Mar 1949
TL;DR: In this paper, the results obtained from tests extending from 1943 to 1946 which were made to determine the meteorological factors controlling the propagation of centimeter waves were summarized and the correlation between the radio results and the various meteorological parameters was studied in the light of current theories of microwave propagation.
Abstract: This paper summarizes the results obtained from tests extending from 1943 to 1946 which were made to determine the meteorological factors controlling the propagation of centimeter waves. Oversea paths of 60 and 200 miles off the West Coast of Great Britain were used for the experiments. Continuous records of radio field strengths and frequent measurements of the meteorological conditions along the paths were made. The correlation between the radio results and the various meteorological parameters is studied in the light of current theories of microwave propagation.
TL;DR: Five separate suggestions concerned with the correction and siting of magnetic compasses are put forward, unrelated to each other except in the fact that they have all resulted from viewing the problems from a deliberately unconventional standpoint.
Abstract: This paper describes a number of proposals concerning the correction of the errors of magnetic compasses. The first proposal concerns the correction, by means of special soft iron correctors, of the deviating effects of both vertically and horizontally induced magnetization.A scheme for removing constant error without having to use algebraic addition or even having to record the existing deviations is next described.A scheme is then suggested whereby, provided no constant deviation is present, a compass may be corrected for the effects of permanent magnetism in four operations, each of which consists of the complete removal of deviation on a particular heading by a particular corrector.Possibilities of putting compasses below decks without seriously affecting their performance are also discussed; these particular suggestions cannot apply to merchant ships in which magnetic cargo is being transported. Suggestions are also made of correcting the compass by modifying the disposition of the magnetic material in the bridge structure instead of by adding a corrector to the compass binnacle.Finally, a scheme is introduced to maintain an aeroplane compass mounting parallel to the surface of the Earth during a level turn by using the centrifugal force due to the turn.This paper puts forward five separate suggestions concerned with the correction and siting of magnetic compasses. The suggestions are unrelated to each other except in the fact that they have all resulted from viewing the problems from a deliberately unconventional standpoint. Some of the solutions proposed may be of interest to those concerned with magnetic compasses in ships, aircraft and vehicles.
TL;DR: In this paper, Shreve, Pomeroy and Mysels found that pure aluminium laurate which had been dried in vacuo over phosphorus pentoxide at room temperature gave 2·5 ± 0·4 per cent of water when examined with the Karl Fischer reagent.
Abstract: IN the course of a study of the water sorption of aluminium soaps, Shreve, Pomeroy and Mysels1 found that pure aluminium laurate which had been dried in vacuo over phosphorus pentoxide at room temperature gave 2·5 ± 0·4 per cent of water when examined with the Karl Fischer reagent. They maintained, consequently, that the reagent gives misleading results because, under the conditions of the determination, soap molecules react with each other, or with free acid, to give water, thus: