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Article
Publication date: 14 November 2008

Giacomo Oliveri and Mirco Raffetto

The paper's purpose is to deduce additional information on the accuracy of finite element simulators for electromagnetic problems involving effective models of metamaterials.

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Abstract

Purpose

The paper's purpose is to deduce additional information on the accuracy of finite element simulators for electromagnetic problems involving effective models of metamaterials.

Design/methodology/approach

The objective is achieved by solving, with a well known commercial simulator, many different configurations of two types of electromagnetic problems: a free‐space scattering by a sphere and a waveguide discontinuity problem. Such problems are known to be able to point out the difficulties of numerical simulators. On the other hand, they are representative of two important classes of problems and can provide indications on what can happen in other cases.

Findings

This analysis confirms that the numerical errors can be important just in close proximity of the interface between metamaterials and standard media. Small values of loss tangents can be sufficient to obtain very accurate results. Adaptive mesh generators should not be used in the presence of negligible values of the loss tangents. For more uniform meshes the results are satisfactory, with sufficiently fine meshes. When the magnitude of the real parts of the effective dielectric permittivity of a metamaterial and of the adjacent standard media are significantly different, the accuracy is satisfactory in any case.

Research limitations/implications

The results are obtained by considering problems of two types. There is no guarantee that all the deductions apply to other models.

Practical implications

To design practical devices involving metamaterials reliable electromagnetic simulators are necessary. The reported results seem to indicate that it is possible to adopt some countermeasures against the possible lack of accuracy of finite element simulators in the presence of effective models of metamaterials.

Originality/value

For the first time, to the best of authors' knowledge, an extensive analysis on the accuracy of finite element simulators for critical problems involving metamaterials has been carried out. Some simple suggestions to improve their reliability in these cases are provided.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 December 1900

In 1899 the medical practitioners of Dublin were confronted with an outbreak of a peculiar and obscure illness, characterised by symptoms which were very unusual. For want of a…

70

Abstract

In 1899 the medical practitioners of Dublin were confronted with an outbreak of a peculiar and obscure illness, characterised by symptoms which were very unusual. For want of a better explanation, the disorder, which seemed to be epidemic, was explained by the simple expedient of finding a name for it. It was labelled as “beri‐beri,” a tropical disease with very much the same clinical and pathological features as those observed at Dublin. Papers were read before certain societies, and then as the cases gradually diminished in number, the subject lost interest and was dropped.

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British Food Journal, vol. 2 no. 12
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 1 October 1900

The latest information from the magazine chemist is extremely valuable. He has dealt with milk‐adulteration and how it is done. His advice, if followed, might, however, speedily…

55

Abstract

The latest information from the magazine chemist is extremely valuable. He has dealt with milk‐adulteration and how it is done. His advice, if followed, might, however, speedily bring the manipulating dealer before a magistrate, since the learned writer's recipe is to take a milk having a specific gravity of 1030, and skim it until the gravity is raised to 1036; then add 20 per cent. of water, so that the gravity may be reduced to 1030, and the thing is done. The advice to serve as “fresh from the cow,” preferably in a well‐battered milk‐measure, might perhaps have been added to this analytical gem.

Details

British Food Journal, vol. 2 no. 10
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 1 September 1900

There are very few individuals who have studied the question of weights and measures who do not most strongly favour the decimal system. The disadvantages of the weights and…

85

Abstract

There are very few individuals who have studied the question of weights and measures who do not most strongly favour the decimal system. The disadvantages of the weights and measures at present in use in the United Kingdom are indeed manifold. At the very commencement of life the schoolboy is expected to commit to memory the conglomerate mass of facts and figures which he usually refers to as “Tables,” and in this way the greater part of twelve months is absorbed. And when he has so learned them, what is the result? Immediately he leaves school he forgets the whole of them, unless he happens to enter a business‐house in which some of them are still in use; and it ought to be plain that the case would be very different were all our weights and measures divided or multiplied decimally. Instead of wasting twelve months, the pupil would almost be taught to understand the decimal system in two or three lessons, and so simple is the explanation that he would never be likely to forget it. There is perhaps no more interesting, ingenious and useful example of the decimal system than that in use in France. There the standard of length is the metre, the standard of capacity the cubic decimetre or the litre, while one cubic centimetre of distilled water weighs exactly one gramme, the standard of weight. Thus the measures of length, capacity and weight are most closely and usefully related. In the present English system there is absolutely no relationship between these weights and measures. Frequently a weight or measure bearing the same name has a different value for different bodies. Take, for instance, the stone; for dead meat its value is 8 pounds, for live meat 14 pounds; and other instances will occur to anyone who happens to remember his “Tables.” How much simpler for the business man to reckon in multiples of ten for everything than in the present confusing jumble. Mental arithmetic in matters of buying and selling would become much easier, undoubtedly more accurate, and the possibility of petty fraud be far more remote, because even the most dense could rapidly calculate by using the decimal system.

Details

British Food Journal, vol. 2 no. 9
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 1 January 1901

IN order to be able to discriminate with certainty between butter and such margarine as is sold in England, it is necessary to carry out two or three elaborate and delicate…

47

Abstract

IN order to be able to discriminate with certainty between butter and such margarine as is sold in England, it is necessary to carry out two or three elaborate and delicate chemical processes. But there has always been a craving by the public for some simple method of determining the genuineness of butter by means of which the necessary trouble could be dispensed with. It has been suggested that such easy detection would be possible if all margarine bought and sold in England were to be manufactured with some distinctive colouring added—light‐blue, for instance—or were to contain a small amount of phenolphthalein, so that the addition of a drop of a solution of caustic potash to a suspected sample would cause it to become pink if it were margarine, while nothing would occur if it were genuine butter. These methods, which have been put forward seriously, will be found on consideration to be unnecessary, and, indeed, absurd.

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British Food Journal, vol. 3 no. 1
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 1 November 1900

A pæan of joy and triumph which speaks for itself, and which is a very true indication of how the question of poisonous adulteration is viewed by certain sections of “the trade,”…

62

Abstract

A pæan of joy and triumph which speaks for itself, and which is a very true indication of how the question of poisonous adulteration is viewed by certain sections of “the trade,” and by certain of the smaller and irresponsible trade organs, has appeared in print. It would seem that the thanks of “the trade” are due to the defendants in the case heard at the Liverpool Police Court for having obtained an official acknowledgment that the use of salicylic acid and of other preservatives, even in large amounts, in wines and suchlike articles, is not only allowable, but is really necessary for the proper keeping of the product. It must have been a charming change in the general proceedings at the Liverpool Court to listen to a “preservatives” case conducted before a magistrate who evidently realises that manufacturers, in these days, in order to make a “decent” profit, have to use the cheapest materials they can buy, and cannot afford to pick and choose; and that they have therefore “been compelled” to put preservatives into their articles so as to prevent their going bad. He was evidently not to be misled by the usual statement that such substances should not be used because they are injurious to health— as though that could be thought to have anything to do with the much more important fact that the public “really want” to have an article supplied to them which is cheap, and yet keeps well. Besides, many doctors and professors were brought forward to prove that they had never known a case of fatal poisoning due to the use of salicylic acid as a preservative. Unfortunately, it is only the big firms that can manage to bring forward such admirable and learned witnesses, and the smaller firms have to suffer persecution by faddists and others who attempt to obtain the public notice by pretending to be solicitous about the public health. Altogether the prosecution did not have a pleasant time, for the magistrate showed his appreciation of the evidence of one of the witnesses by humorously rallying him about his experiments with kittens, as though any‐one could presume to judge from experiments on brute beasts what would be the effect on human beings—the “lords of creation.” Everyone reading the evidence will be struck by the fact that the defendant stated that he had once tried to brew without preservatives, but with the only result that the entire lot “went bad.” All manufacturers of his own type will sympathise with him, since, of course, there is no practicable way of getting over this trouble except by the use of preservatives; although the above‐mentioned faddists are so unkind as to state that if everything is clean the article will keep. But this must surely be sheer theory, for it cannot be supposed that there can be any manufacturer of this class of article who would be foolish enough to think he could run his business at a profit, and yet go to all the expense of having the returned empties washed out before refilling, and of paying the heavy price asked for the best crude materials, when he has to compete with rival firms, who can use practically anything, and yet turn out an article equal in every way from a selling point of view, and one that will keep sufficiently, by the simple (and cheap) expedient of throwing theory on one side, and by pinning their faith to a preservative which has now received the approval of a magistrate. Manufacturers who use preservatives, whether they are makers of wines or are dairymen, and all similar tradesmen, should join together to protect their interests, for, as they must all admit, “the welfare of the trade” is the chief thing they have to consider, and any other interest must come second, if it is to come in at all. Now is the time for action, for the Commission appointed to inquire into the use of preservatives in foods has not yet given its decision, and there is still time for a properly‐conducted campaign, backed up by those “influential members of the trade” of whom we hear so much, and aided by such far‐reaching and brilliant magisterial decisions, to force these opinions prominently forward, in spite of the prejudice of the public; and to insure to the trades interested the unfettered use of preservatives,—which save “the trade” hundreds of thousands of pounds every year, by enabling the manufacturers to dispense with heavily‐priced apparatus, with extra workmen and with the use of expensive materials,—and which are urgently asked for by the public,—since we all prefer to have our foods drugged than to have them pure.

Details

British Food Journal, vol. 2 no. 11
Type: Research Article
ISSN: 0007-070X

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