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The purpose of this paper is to investigate the ionization and dispersion effects in combination with the inhomogeneity of soil simultaneously on the effective lengths of counterpoise wires.

Improved multi-conductor transmission line model is used for computing effective length of counterpoise wires considering all aspects of soils.

The simulation results show that the ionization and dispersion effects simultaneously results in placing the effective length between situations where only one effect is considered. Also, predicting formulae for effective length of counterpoise wires considering all effects are proposed.

A sensitivity analysis on the effective lengths of counterpoise wires considering all aspects of soils is carried out.

BEFORE DISCUSSING the treatment of the various subjects in a course, one must look closely at the purposes for which the course was designed, at the course's structure, and at the type of student likely to be taking it. The General Course (Engineering) contains four technical subjects:

THE property possessed by certain discharges of radiating relatively large proportions of their energy in the visible part of the spectrum is well known. Thus efficiencies of the order of 50–70 lumens per watt are obtained from high pressure mercury vapour and sodium vapour discharges.

This paper aims to focus on the inclusion of the frequency behavior of grounding system effect on surge arrester (SA) model parameters’ estimation.

The grounding system impedance and its frequency behavior are the factors that have influence on the SA performance. Up to now, the grounding system impedance effect and the frequency behavior of the soil parameters have not been studied for the estimation of the parameters of the SA frequency-dependent model. In this paper, the grounding system’s influence on the SA dynamic model has been simulated for rod- and counterpoise-shaped electrodes. Particle swarm optimization with a grey wolf optimization algorithm has been implemented as an optimization algorithm to adjust the parameters of the SA dynamic model.

The results show that the frequency behavior of the grounding impedance and soil electrical parameters can impress the optimum parameters of the SA frequency-dependent model and should be considered for more reliable results. Also, the results evidence that the proposed optimization method provides more accurate results compared to other optimization methods.

To the best of the authors’ knowledge, this work is one of the first attempts to investigate the effect of frequency grounding system on SA frequency-dependent model parameters.

The purpose of this paper is to investigate the simultaneous effects of ionization and dispersion of soil on the impulse behavior of grounding electrodes under first and subsequent stroke currents.

A recently introduced technique called improved multi-conductor transmission line (MTL) is simplified for grounding electrodes buried in both-affected soils.

The simulation results show that including the two effects simultaneously in highly resistive soils under high-valued subsequent stroke current is recommended. Otherwise, simultaneous effects can be disregard.

To the best of the authors’ knowledge, there is no research on sensitivity analyses for the simultaneous inclusion of the two effects on the effective length and the induced voltage on the soil surface. To this end, the simplified MTL is applied to the grounding electrodes. The simulation results show that the computational efficiency in comparison with previous methods is, first, considerably increased. Second, the simultaneous effects result in decreasing the soil surface voltage with respect to situations where either ionization or dispersion is taken into account (single-affected soils). In other words, the performance of grounding systems is improved. Third, the effective length in both-affected soil is has a middle value with respect to the single-affected soil. Such findings practically and financially are of importance.

The writer was sent from the Royal Aircraft Establishment as a member of C.I.O.S. Party No. 641 which visited the Dornier Works, Friedrichshafen, during the period July 21–27, 1945. Since the main purpose of the visit was to investigate the production methods and capacity of Dorniers, these notes, which describe the airframe strength‐test equipment and test methods used at Dorniers, were not included in the team's production report.

An information society is one in which labour has been intellectualised; one in which the expression ‘to earn one's daily bread by the sweat of one's brow’ sounds decidedly anachronistic. Employment in the information sector of the economy is growing apace — counterpoising stagnation and decline in the traditional manufacturing industries. Soon, terms such as information worker, knowledge engineer, ideas processor, symbol manipulator will be as common as weaver, cartwright and miller once were. As if to underscore this trend, the US Bureau of Labor recently reclassified the white‐collar work‐force as ‘information workers’. The soi disant information society has come of age. What began life as a sociological construct and then became a feature of futurologists' patois before degenerating into a media cliché, has finally achieved respectability through endorsement by economic and political analysts. How has this come about and what does it portend?

AS little information has been published, the subject of bombsights is shrouded in mystery, and hence from time to time it is natural that the daily press should make amazing disclosures concerning the alleged performances of new types of bombsights; including an American one capable of dropping bombs into a barrel from the sub‐stratosphere. Such statements can be viewed in their proper perspective if the functions of a bombsight are understood. The state of the enemy ground defences dictate the requirements of a bombsight, since if no opposition is met it is possible to drop delayed action bombs from a low altitude without using a bombsight. As ground defence improves, it is necessary to bomb from a greater height, and so the need for a bombsight increases. It is also necessary to bomb from a great height if armour‐piercing bombs are used, so that they can attain their terminal velocity. Unfortunately, or fortunately, depending on one's position at bomb release, accurate bomb aiming is a complicated matter, and errors increase with height. Thus, as high altitude bombing becomes necessary, so the bombsight becomes more complicated, and as ground defences become more accurate the operational difficulties of the aircraft increase and make still further demands on the bombsight. Thus, as the war proceeds a steady evolution can be observed in the types of bombsight used, as will be seen from those described in this article. Anti‐aircraft gunsights have progressed from simple open ones to those incorporated in the predictor system, and in a like manner bombsights have made similar progress. As each sight has had a bearing on the design of the other, it is interesting to compare the requirements and operation of a bombsight with those required for an anti‐aircraft gunsight.

The equipment described in the following article was installed in a German Messerschmidt 109 shot down over the Thames estuary. The aeroplane was shipped to the United States through arrangements made by Mrs. Winston Churchill, honorary sponsor of “Bundles for Britain.” Upon its arrival Lear engineers removed the radio apparatus, and the equipment was thoroughly tested by Mr. Lear in his laboratories at Lear Avia, Inc., Piqua, Ohio. A covering note accompanying the article says: “Mr. Lear's report on the German radio equipment stressed four points: (1) The Germans have apparently ‘frozen’ their military radio design since 1933, and standardized their tubes and components for ease of mass production and servicing. (2) Shortages of war materials are indicated by the use of ceramics instead of plastics, fibre instead of rubber and special alloys instead of aluminium. (3) The extremely limited range of the transmitter (around 5 miles) and the provision for higher power output, indicate that most German warplancs in a given squadron can talk only to one another, while only the leader can communicate with his base. (4) German aircraft radio apparatus found in the Messerschmidt cannot pass U.S. Government lest for even commercial radio equipment, and weighs more than comparable American apparatus.”

EMPHASISING the world‐wide nature of aerospace, Farnborough 1974 was particularly notable for the arrival of the record‐breaking transatlantic aircraft at the beginning of the show, first public appearances of two new British aircraft, and opportunities to see the A300B Airbus and the TriStar in the air and on the ground. Aircraft in the flying display also included Concorde and types new to Britain such as the F15 Eagle and the Alpha Jet as well as the VFW 614 and various helicopters. More than 400 companies from ten countries were represented in the largest display of equipment ever assembled here which covered every aspect of aircraft construction and operation. Also available was news of the Panavia flight‐test programme and the progress of other multi‐national ventures.