Electrical instrument-making in Holland

Summary We should organize and develop the production of electrical measuring instruments similar to those made by Dutch firms, such as rack-mounted indicating instruments of a nominal grade of 0.5 (and higher) and scale angles of 90 and 240°; rack-mounted bimetallic pointer instruments (these instruments have been developed by the Kiev Polytechnic Institute); rack-mounted pointer instruments with built-in control and signaling contacts used for many automatic and semiautomatic processes.     

P. F.

Abstract

The effect of pulse duration and electrode type (copper or graphite) on the pick-up of carbon in the surface of a die steel shaped using electrodischarge machining and on surface microcracks has been studied. The present work suggests that the number and the size of surface microcracks increase with pulse duration when machining with a copper electrode, but there is some evidence to suggest that, when using a graphite electrode, the number and the length of microcracks and the average thickness of the recast layer may be greatest at intermediate (75–150μs) pulse durations. Although no definite conclusion can be drawn from the results, it is suggested that this may be because the manner of decay of the temperature field after each pulse is determined by both electrode material and pulse duration. At high current densities and long pulse durations, the length and frequency of microcracks is increased greatly at the corners of specimens machined using a graphite electrode, but this occurred to a much lesser extent when using a copper electrode – a difference that would seem to reinforce the suggestion that the characteristics of the temperature field after each pulse depend on the electrode material. It was concluded that carbon was absorbed from the dielectric (paraffin) rather than from the electrode. The amount of copper absorbed did not depend on pulse duration.

MST/1040     

多彩的城市动脉

“FromAtoB”公共设计事务所位于荷兰的乌得勒支市，这支设计团队专门为公共空间和公共交通做设计。团队里的工业设计师、平面设计师和建筑师擅长二维和三维项目的设计。不久前，“FromAtoB”设计事务所推出了许多形象设计，为公共交通系统提供了醒目和出色的识别。这些遍布城市动脉的手笔成了让人难以忘怀的亮点。本期《Design》的特约记者将导游大家一饱眼福。     

F.C. Williams

F.C. Williams spent his whole professional life in inventive research. He defined invention as a forward step which is not taken as the result of logical processes on the available data. In his career there were many such forward steps, including inventing circuits for aircraft identification using radar, the computer storage medium used extensively in the early days of computer memory, the structure of the operational amplifier, variable-speed machines and speed control systems. This paper descibes the work of F.C. Williams     

M. F. Romanova

Measurement Techniques -     

Reply by C. F. Hendriks

Letter to the Editor

Reply by C. F. Hendriks     

R.F. sputtering of plastics

This paper outlines the application of r.f. sputtering to plastic as a means of obtaining thinner dielectric layers with good electrical properties for use in the capacitor industry.The construction and characteristics of the sputtering system employed to obtain thin films of PTFE are described. A brief résumé of the differences observed between such films and conventional PTFE is included together with a short discussion of the observed electrical behaviour.