Search results

Another Christmas month is upon us, following it seems quickly on others that have been. Such is the relativity of Time, it is not yesteryear, but could be yester‐month or even yester‐week. The seasons pass like youth, all too soon. Our minds return to other Christmas months of yore — “Memories are like Christmas roses!”, the old saying goes. The children, singing much‐loved hymns and carols, happy family settings, a birth, christening, so much to look forward to in the new year. There are not always such happy memories, but memories just the same — Christmas in war‐time, Earth's joys growing dimmer each year, change and decay, life drawing to a close for many a soul; old folk tend to see Christmas as a time of passing, of leaving the world behind.

The purpose of this paper is to provide a detailed review of radiation dosimetry techniques based on optical fibre dosimeters. It presents a comprehensive bibliography of the current research activities in the area.

A range of published work on optical fibre radiation dosimeters are presented, with the merits and limitations discussed. Each radiation dosimetry technique is discussed in turn, providing examples of dosimeters using such techniques reviewed. The main focus is on gamma radiation although other radiation dosimeters are considered.

This paper provides information on the wide range of research activity into radiation dosimeters. The dose ranges of these dosimeters are presented, along with the advantages and disadvantages of different dosimetry techniques.

A comprehensive review of published research in the area of solid radiation dosimetry is presented in this paper. It provides an individual with a review of the various techniques used and most recent research in that field.

The purpose of this paper is to describe the techniques and technologies used in a selection of sensors which operate in extreme environments.

Following a short introduction, this paper discusses the technologies used in a range of sensors, principally accelerometers and pressure, temperature and displacement sensors, used in environments characterised by elevated temperatures, radiation and high shock and vibration levels.

The paper shows that a range of different strategies is employed to allow sensors to operate in extreme environments. These include specialised designs, novel sensing technologies and others which are inherently capable of withstanding extreme conditions and materials which can perform in, or which are resistant to, these environments. Several new technologies are under development which aim to extend sensor performance to new levels.

This paper provides details of the technologies used in a range of sensors aimed at applications in extreme environments.

This paper aims to describe the effects of radiation on certain classes of sensors and electronic devices and discusses the sensors used in high radiation environments.

Following an introduction, this paper firstly discusses the effects of radiation on semiconductors. It then considers the sensor technologies employed in high radiation applications and examines the impact of radiation on MEMS devices. Finally, it describes a radiation‐tolerant imaging sensor technology.

Ionising and non‐ionising radiation in terrestrial and space environments can exert a detrimental effect on semiconductor devices and has led to the development of a range of radiation hardening technologies. Most of the sensors used in nuclear power plants utilise long‐established and well‐characterised technologies which are inherently radiation‐tolerant but silicon MEMS devices are more prone to damage and a range of failure mechanisms have been identified. Most conventional image sensors are susceptible to radiation damage but a radiation‐hard technology termed the charge‐injection device has been developed which overcomes these problems.

This paper provides details of the sensor technologies used in high radiation applications.

THE JET AGE of today and the Space Age of tomorrow would not be possible without the recent developments in specialised lubricants that have increased the capabilities of fluids, greases, solid films, plastics, ceramics and other specialised lubricating agents. The present and potential use in aeronautical and astronautical flight have imposed and will continue to levy requirements upon lubricants that were beyond the vision or imagination of the lubrication expert of a decade ago. This article does not intend to create the illusion that all our problems have been solved. Rather, it is intended to present the new concepts and capabilities of some of the present products and the potential of the new developments on the basis of knowledge gained through both actual use and through research and development efforts.

Times are indeed a‐changing. Once, the night‐owl, roistering the hours of darkness away, could claim that he “came home with the milk!”, but not any more.

The purpose of this paper is to investigate the effect of materials, three dimensional (3D) structure and number of fabric layers on ultraviolet protection factor (UPF), air permeability and thickness of fabrics.

Total 24 fabrics samples were developed using two 3D structures and two weft materials. In warp direction cotton (CT) yarn and in weft direction polypropylene (PP) and polyester (PET) were used. Air permeability, thickness and UPF testings were performed and relationship among fabric layers, air permeability, thickness and UPF was developed.

UPF and thickness of fabrics increases with number of fabric layers, whereas air permeability decreases with the increase in number of fabric layers. Furthermore, change of multilayer structure from angle interlock to orthogonal interlock having same base weave does not give significant effect on UPF. However, change of material from polyester (PET) to polypropylene (PP) has a dominant effect on UPF. Minimum of three layers of cotton/polyester fabric, without any aid of ultraviolet radiation (UV) resistant coating, are required to achieve good. Cotton/polyester fabrics are more appropriate for outdoor application due to their long-term resistance with sunlight exposure.

Long-term exposure to UV is detrimental. So, there is need of proper selection of material and fabric to achieve ultraviolet protection. 3D fabrics have yarns in X, Y as well as in Z directions which provide better ultraviolet protection as compared to two dimensional (2D) fabrics. In literature, mostly work was done on ultraviolet protection of 2D fabrics and surface coating of fabrics. There is limited work found on UPF of 3D woven fabrics.

A paper with the above title was presented by P. E. B. Vaile, A.M.I.Mech.E., for discussion at a meeting of the Institution of Mechanical Engineers at the Social Club of Hoffmann Manufacturing Co. Ltd., Chelmsford, on 14th September. The paper was sponsored by the Lubrication Group in conjunction with the Nuclear Energy Group. We give here extracts from this paper. Copies of the complete paper are available from The Institution of Mechanical Engineers, 1 Birdcage Walk, London, S.W.1., who invite written communications thereon, which should reach them not later than 31st October. The first part of this paper dealt with industrial power reactors of the CO2 cooled, graphite‐moderated types, high‐temperature gas‐cooled types, etc., and gave details of the U.K.A.E.A. requirements for nuclear lubricants.

AMONGST the many engineering problems associated with the new field of nuclear power plants is that of lubricants. The problem here is more to do with lubricants than lubrication since in spite of very high temperatures, existing products are generally capable of providing adequate lubrication, even although some special materials may need to be devised to provide longer life and special methods of application may be required. In most cases, pumps and turbines will operate at similar speeds and with similar bearing loads as those in conventional power stations and conventional high grade lubricants will, in most cases, meet the bill.