Application of thermoelectric aging models to polymeric insulation in cable geometry

The life expressions of models of insulation ageing are functions of temperature and field as well as material parameters. A methodology is presented that allows these models to be applied to a cable geometry in which there is a radial variation of both field and temperature. In this way material parameters can be extracted from cable data. The methodology is illustrated using one such model and the parameters deduced from cable failure distributions are compared with those obtained for thin films. This comparison allows conclusions to be drawn about how the ageing process affects specimens of the same material with different volumes

Application of polymer ageing models to power cables

Ageing models have been developed to predict the lifetime of polymeric insulation subject to electro-thermal stresses. We present here a method for applying the models to situations in which the field is not constant over the whole specimen, as for cable geometry. The method has been applied to characteristic lifetime data from AC ageing experiments on cables. The results are presented, and the effect of insulation volume upon the model parameters is discussed

Material Morphology and energy barriers to electrical ageing

A distribution of the parameters representing activation energy of the ageing process within the Dissado-Montanari-Mazzanti (DMM) lifetime model has been shown to model experimental lifetime distributions of PET films well. The results imply small differences in the local environments of the moieties involved in the ageing process. Very small changes in the minimum activation energy values have a pronounced effect on the resultant lifetimes of polymer specimens. Changes in the distributions of activation energies with field and temperature can be explained by assuming the ageing process to be one whereby polymer segments on lamella surfaces crystallise to create free volume within the polymer

Relations of literature, science & philosophy in university education

RELATIONS OF LITERATURE, SCIENCE & PHILOSOHPY: Thought distinguished from feeling;- series of minds founded on this distinction. - The general and the particular distinguished, and a second series of minds suggested;- a corresponding series cf expressions of mentality;- diagram. Summary to this point. Of the scientific method,- ancient philosophy. The development of the inductive method,- Dr» Reid quoted;-the growth of science;- oscillation;- the likeness of the new to the old philosophy recapitulation.*THE FOREGOING ANALYSIS AS BEARING ON UNIVERSITIES: A. Nature & Function of University Education: Meaning of university Education defined,- Professor Butcher quoted. The discussion introduced by a list of materials.B(1) Literature: Why music and fine art are not essential in university education;- literature completely representative of the artistic spirit, but improperly used.- Ancient literature, modern literature.- Common arguments in favour of literary training stated and refuted, The real reason why literature must be studied;- the need for changed method in the study of literature.* Summary and conclusions regarding literature.B.(2) Science & Philosophy Limited nature of most arts courses;- gaps in arts courses;- enough subjects included, but why always the same? The real object of scientific training;- The best plan of education in science & philosophy;- Omission of natural science from most arts courses;- this omission not obviated by Scottish "honours" courses,- comparison of these with those of Cambridge. Advantages of free choice of subjects. Need for philosophy and practical suggestions. The argument confirmed by reference to history. Summary,APPLICATION OF THE FOREGOING TO EDINBURGH UNIVERSITY: The teaching organisation in Edinburgh. The use that is made of this organisation, and the use that might be

On the Leaves of Climbing Plants

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The decay of space charge in a glassy epoxy resin following voltage removal

The PEA technique is used to measure the distribution of space charge in an epoxy resin after polarisation for one week at an applied field of 7.14kV/mm over a range of temperatures. The decay of the space charge is followed for times up to 114 hours after removal of the voltage and analysed in terms of a number of alternative decay mechanisms. It is shown that the rate-determining stage of the decay mechanism is that of a thermally activated process that has been associated with charge de-trapping. At times greater than 102s the de-trapping process behaves as though the space charge field does not exist and the retention time of the space charge depends only upon the depth of the deepest occupied traps and the temperature

Nanodielectics (A "Universal" Panacea for Solving All Electrical Insualation Problems?)

This text summarizes the keynote presentation that is based on the full-length paper of the same title. Dr. Fréchette's oral presentation should not be seen as a summary of the “Brainstorm paper” but a glance at some major accomplishments, hinrances and still remaining questions relative to nanodielectrics. Are nanodielectrics a “universal” panacea? The answer to that question is no - but they've got a lot of potential

Some Abnormal Reactions of Organomagnesium Halides

Nitro and nitroso groups react with methylmagnesium halides (and other RMgX compounds) to give methane and some ethane. The gases so evolved make it necessary to correct for the ordinary determination of active hydrogen by means of the Zerewitinoff method. Accordingly, the new hydroxy structure proposed for o-nitrobenzaladehyde finds no support on the basis of gas evolved when treated with alkylmagnesium halides

Control Of Norway Rats In Sewer And Utility Systems Using Pulsed Baiting Methods

There were 1,288 sewer and 235 other utility manholes baited to control Norway rat (Rattus norvegicus) populations in downtown Boston using pulsed-baiting methods. About 15% of all sewer, 18% of phone, and 26% of electric manholes had rat activity. Sewer populations were most associated with residential areas with low flow, small diameter (\u3c61 cm) brick sewers; in those circumstances, up to 38% of manholes had rat activity. Bait consumption in sewers (high risk areas) was 91 % below baseline, five months after the fourth baiting period. Bait consumption and the number of active sewer holes were 96% and 87% below baseline, respectively, when seasonal maintenance baiting was last initiated. Reinfestation of phone/electric manholes was so minimal that maintenance baiting was not necessary or cost-effective. Subsurface baiting should be an integral part of urban rodent control programs