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This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less noise.

Aeroengine performance analyses were carried out covering a wide range of parameters for more complex thermodynamic cycles. This led to the identification of major component features and the establishing of preconceptual aeroengine layout concepts for various types of recuperated and ICR variants.

Novel aeroengine architectures were identified for heat exchanged turboshaft, turboprop, and turbofan variants covering a wide range of applications. While conceptual in nature, the results of the analyses and design studies generally concluded that heat exchanged engines represent a viable solution to meet demanding defence and commercial aeropropulsion needs in the 2015‐2020 timeframe, but they would require extensive development.

As highlighted in Parts I and II, early development work was focused on the use of recuperation, but this is only practical with compressor pressure ratios up to about 10. For today's aeroengines with pressure ratios up to about 50, improvement in SFC can only be realised by incorporating intercooling and recuperation. The new aeroengine concepts presented are clearly in an embryonic stage, but these should enable gas turbine and heat exchanger specialists to advance the technology by conducting more in‐depth analytical and design studies to establish higher efficiency and “greener” gas turbine aviation propulsion systems.

It is recognised that meeting future environmental and economic requirements will have a profound effect on aeroengine design and operation, and near‐term efforts will be focused on improving conventional simple‐cycle engines. This paper has addressed the longer‐term potential of heat exchanged aeroengines and has discussed novel design concepts. A deployment strategy, aimed at gaining confidence with emphasis placed on assuring engine reliability, has been suggested, with the initial development and flight worthiness test of a small recuperated turboprop engine for UAVs, followed by a larger recuperated turboshaft engine for a military helicopter, and then advancement to a larger and far more complex ICR turbofan engine.

To advance the design of heat exchanged gas turbine propulsion aeroengines utilising experience gained from early development testing, and based on technologies prevailing in the 1970‐2000 time frame.

With emphasis on recuperated helicopter turboshaft engines, particularly in the 1,000 hp (746 kW) class, detailed performance analyses, parametric trade‐off studies, and overall power plant layouts, based on state‐of‐the‐art turbomachinery component efficiencies and high‐temperature heat exchanger technologies, were undertaken for several engine configuration concepts.

Using optimised cycle parameters, and the selection of a light weight tubular heat exchanger concept, an attractive engine architecture was established in which the recuperator was fully integrated with the engine structure. This resulted in a reduced overall engine weight and lower specific fuel consumption, and represented a significant advancement in technology from the modified simple‐cycle engines tested in the late 1960s.

While heat exchanged engine technology advancements were projected, there were essentially two major factors that essentially negated the continued study and development of recuperated aeroengines, namely again as mentioned in Part I, the reduced fuel consumption was not regarded as an important economic factor in an era of low‐fuel cost, and more importantly in this time frame very significant simple‐cycle engine performance advancements were made with the use of significantly higher pressure ratios and increased turbine inlet temperatures. Simply stated, recuperated variants could not compete with such a rapidly moving target.

Establishing an engine design concept in which the recuperator was an integral part of the engine structure to minimise the overall power plant weight was regarded as a technical achievement. Such an approach, together with the emergence of lighter weight recuperators of assured structural integrity, would find acceptance around the year 2000 when there was renewed interest in the use of more efficient heat exchanged variants towards the future goal of establishing “greener” aeroengines, and this is discussed in Part III of this paper.

Interest is currently being expressed in heat exchanged propulsion gas turbines for a variety of aeroengine applications, and in support of this, the aim of this paper is to evaluate the relevance of experience gained from development testing of several recuperated aeroengines in the USA in the late 1960s.

Technology status, including engine design features, performance, and specific weight of recuperated propulsion gas turbines based on radial and axial turbomachinery, that were development tested in the power range of about 300 to 4,000 hp (224 to 2,984 kW) is discussed in Part I.

A successful flight worthiness test was undertaken in the USA of a helicopter powered solely by a recuperated turboshaft engine and this demonstrated a specific fuel consumption reduction of over 25 percent compared with the simple‐cycle engine. However; in an era of low‐fuel cost, and uncertainty about the long‐term structural integrity of the high‐temperature heat exchanger, further development work was not undertaken.

The gas turbines tested were based on conventional simple‐cycle engines with essentially “bolted‐on” recuperators. Optimum approaches to minimize engine overall weight were needed in which the recuperator was integrated with the engine structure from the onset of design, and these are discussed in Part II.

Based on engine hardware testing, a formidable technology base was established, which although dated, could provide insight into the technical issues likely to be associated with the introduction of future heat exchanged aeroengines. These are projected to have the potential for reduced fuel burn, less emissions, and lower noise, and recuperated and intercooled turboshaft, turboprop, and turbofan variants are discussed in Part III.

A well‐prepared and presented proposal or tender can give a company a strong competitive edge. It is, however, an aspect of marketing that is often neglected.

This study aims to examine the antecedents of perceived value in the Airbnb context using the variables of perceived benefits (i.e. monetary saving, hedonic benefit, novelty and social interaction) and perceived risks (i.e. performance, physical, psychological and time).

The study population was Airbnb users in South Korea. This study applied a survey research method using a questionnaire. A link to the survey was sent via e-mail to panel members of a multinational research company.

The results revealed the positive influence of monetary saving, hedonic benefit and novelty on perceived value and the negative influence of psychological risk on perceived value.

The results of this study, which identified the specific factors that influence Airbnb users’ perception of value, can assist Airbnb managers and Airbnb hosts in developing appropriate marketing plans and strategies to enhance the value of their offerings.

This study provided empirical support to the inclusion of affective factors and risk in determining perceived value. Moreover, while previous Airbnb studies focused on consumers from Western countries (e.g. USA and Canada), this study used a sample of South Korean consumers.

The recent epidemic of food poisoning at Nelson, Lancashire, is an event which is unfortunately not unknown in this country, especially in summer time. It has been said that at least two hundred people have been affected more or less seriously, and that there have been four deaths from acute gastro enteritis. Cases of suspected food poisoning are now in many places compulsorily notifiable to the local authority by medical practitioners to whose notice such cases may have been brought in the course of their practice. As far as we know such notification was not made compulsory before the year 1924, when Wakefield obtained powers under a Corporation Act to do so. A large number of places since that time have followed the lead of Wakefield. Thus among watering places, Cleethorpes, Bridlington, Brighton and Bournemouth; among manufacturing centres, Sheffield, Stoke‐on‐Trent, Bradford, Blackburn, Oldbury, Smethwick, Cardiff and Rochdale have powers of compulsory notification.—Cheap, rapid, and frequent means of road and rail transport has in these days resulted in an enormously increased influx of holiday makers from the manufacturing centres into seaside towns during the summer. Here, then, is a floating population amounting to several thousands. They are at a place that has been freely and emphatically advertised as a health resort. The have come for a “change” in every sense of the word. It is high summer. The weather is hot. The holiday spirit in the air. A very natural result is for people to eat more fruit, ice cream, and fancy dishes than they would ordinarily do. Assume through some mischance there are one or two cases of food poisoning. These are now automatically reported to the local authority, which at once institutes investigations, tries to trace the evil to its source, and check it from spreading. A serious outbreak is a damning catastrophe for the place, and may adversely affect its future for years to come. In manufacturing centres the need for action on the part of the local authority is still more urgent. The danger is perennial. It may easily reach the dimensions of an epidemic in a poor and crowded district. The people are there from necessity not from choice, and there they would have to stay even if the place were swept by cholera. In the County of London notification is compulsory under the London County Council (General Powers) Act, 1932, Pt. II., s.7, which says : “ Every registered medical practitioner, if he suspects that a person is suffering from food poisoning shall notify the Medical Officer of Health for the district.” This section it is pointed out, was drawn up on the lines of the Sheffield Corporation Act, 1928, s.190, one of the main Corporation Acts that insist on notification. There seems indeed to be a growing belief that compulsory notification of food poisoning is desirable in the interests of public health. Processed foods are particularly liable to become sources of infection. Thus the Act just quoted, Pt. II. s.5, states that premises used for the sale or manufacture of ice cream; or for the preparation or manufacture of sausages or potted, pressed, pickled, or preserved meat, fish or other food must be registered with the Sanitary Authority of the district. Under the same section registration may be refused or registration may be cancelled. Many towns have similar regulations. This section of the London County Act is founded on the Exeter Corporation Act, 1928, s.111. The fact that the London County Council have adopted these two regulations that had already been “ tried out ” in two important cities of such widely different interests as Sheffield and Exeter is a good illustration of how closely associated all municipal bodies are in matters connected with public health. Medical Officers of Health and Public Analysts are officers of the Ministry of Health, and the Ministry itself is a clearing house for general information, investigation, and the co‐ordination of statistics. The sanitary authority of, and the medical practitioners in, any given district discharge not only admittedly most important but, as it seems to us, complementary duties. Each has knowledge not possessed by the other. Diagnosis in cases of suspected food poisoning is by no means easy. Time is not on the doctor's side so that the sooner the sanitary authority is notified the better are the chances of being able to trace the trouble to its source and to deal with it— assuming, of course, that it did not originate in some piece of purely domestic carelessness or ignorance. The information acquired may be slight, or even negative in any given case, but in the aggregate a fund of knowledge must accumulate that cannot fail in the long run to be of value. In many cases of suspected food poisoning further investigation has shown that they are not due to food poisoning at all. For instance, in one borough nine cases reported were found to be due to “ dietetic indiscretion ”; in another twenty reported cases were only forms of more or less acute digestive disturbance of the ordinary kind; in another it was found that daffodil bulbs had been eaten in mistake for onions. Other instances could be given. Facts like these would seem to support the argument that compulsory notification is unnecessary, but it is surely better that twenty suppositious cases should be reported than that the circumstances of one real case should escape investigation. In other cases the cause may remain unknown, but as to the seriousness of the matter there can be no doubt. In a recent outbreak in a home for “unwanted” children out of thirty‐nine infants in one dormitory twenty‐seven were attacked, and twenty died in from two to four days from some obscure form of gastro enteritis. Bacteriological examination of excreta and vomit yielded negative results. The high rate of mortality was attributed to the poor physical condition of the children when they were admitted to the institution in which they died. The case is admittedly an extreme one. Another was reported of exactly the opposite character. Twelve cases of undoubted food poisoning were reported, but these were of so slight a character that no action was taken in regard to the circumstances. In general, however, there is no room for giving the benefit of the doubt. The error—even if it may be so called—of reporting what turns out to be a case of indigestion instead of one of food poisoning is an error on the right side. A question arose recently in the House of Commons as to whether it was necessary to retain an Act on the Statute Book when there had been no prosecutions under the Act. It will be remembered that the Solicitor‐General replied that the mere fact that the Act was on the Statute Book had a very salutary effect. As far as it may be possible to draw an analogy it seems that even better reasons exist not only for retaining, but for extending, compulsory notification of cases of suspected food poisoning. Registration and inspection of premises, plant, storage conditions, and the food itself in places where food is prepared and sold is now a general practice in all centres of population. How necessary this is a glance at the Law Reports of this journal will show. The state of the places mentioned in the records of the prosecution was often such as to ensure them being potential centres of food poisoning. Had it not been for the vigilance of the respective sanitary authorities they would have become actively and permanently so. Such prosecutions are comparatively rare having regard to the large number of food shops in existence, but it would certainly be a backward step to cease to register and to inspect.

Tourism development, emerging market entrepreneurship.

This case may be used in lower or upper division courses. Lower division courses may want to focus on the elementary issues of project planning, business plan development, and marketing. Upper division courses will find opportunities to enhance the discussion with ethical dilemmas and more advanced business plan development.

The case takes place in a nature conservancy in Namibia. A local villager wants to open an attraction portraying local customs, traditions, art, and dance for tourists. This case can be used as an introductory strategy case study in at least three types of classes, strategic management, entrepreneurship, or hospitality management. The case presents many opportunities for students to analyze various business topics, including start-up financing, competitive and industry analysis, questions of pricing, product, and promotion, government relations, tourism development, and ethics. It is designed to be taught in either a 1 hour class or a 1.5 hour class with student preparation taking between 2 and 3 hours depending on the questions assigned. If students are asked to complete a business plan the preparation and discussion time will be longer.

Students will demonstrate ability to prepare a business plan, conduct market research, and evaluate potential business idea using Porter's five forces. Students will also demonstrate depth of understanding ethical dilemmas in an emerging and foreign market.

Teaching note.

This public educational conference on our food and drug law has a particular significance. For in the first place it deals with the public law of greatest personal importance to our people ; and that is why it is truly called “ the people's law ” In the second place this law is inadequately known, mainly for three reasons. They are: (a) the general public ordinarily has no direct contact with this law; (b) its official reports do not reach that public, as a rule; and (c) other general publicity about it is insufficient. Furthermore, this conference has the additional value of recalling that our people now enjoy the highest food and drug standards of living ever reached anywhere. That situation has an essential relation to the national welfare ; and it was achieved by the great scientific, technological and economic progress of our food and drug industries. But the food and drug law has played an indispensable role in this achievement.

IT is fitting that a new series of this magazine should be introduced by some reflections on the whole question of book selection, both for the general public and libraries.

The investigation here reported was undertaken to determine certain physical principles and their application to dehydration problems in general. The project was not carried to the point where it was possible to consider the modifications necessary for the different varieties of fruits and vegetables. Factors leading to the deterioration of dehydrated products and the relation which the condition of the fresh material may bear to this deterioration are important phases of the problem not here considered. Spoilage of raw food is due principally to the growth of moulds and bacteria. This growth does not occur when the soluble solids are sufficiently concentrated through the reduction, by drying or by other means, of the water present in foods. Even if they are not killed, the moulds and bacteria remain dormant and harmless in the absence of a suitable medium for their growth. Changes in composition, flavour and appearance, however, may also be brought about by the action of the enzymes present in practically all foodstuffs. As these natural catalytic bodies are not always inactivated by the treatment which stops mould and bacterial action they must be considered in working out methods of dehydration. The outstanding advantage of drying as a method of preserving foods is that the weight and bulk of the products are greatly reduced, thus making possible economy in storage and transportation. The production cost of dehydration compares favourably with that of canning. Dried fruits and vegetables are almost as convenient for use in the home as the fresh products. They need no peeling or other preliminary treatment, and soaking and cooking can often be combined. Only the quantity required need be used when the package is opened; the rest will keep in good condition for a reasonable time. “Dried,” “sun‐dried,” “evaporated” and “dehydrated” are the terms most commonly used to describe dried products. Dried indicates drying by any means; sun‐dried indicates drying without artificial heat; and evaporated implies the use of artificial heat. Evaporated refers more particularly to the use of artificial heat in driers depending for their air circulation on natural draught, while dehydrated implies mechanical circulation of artificial heat. The commercial dehydration of fruits has reached a more advanced stage of development than has the commercial dehydration of vegetables, owing largely to the fact that the public is familiar with sun‐dried and evaporated fruits, whereas it knows comparatively little about dried vegetables. During the World War 8,905,158 lbs. of dehydrated vegetables, divided as follows, were shipped to the United States Army overseas: Potatoes, 6,437,430lbs.; onions, 336,780; carrots, 214,724; turnips, 56,224; and soup mixture, 1,860,000. In the years immediately following 1919 the drying of vegetables declined rapidly, and for the last 10 years or more production has been compartively small. To be successful, a dehydration plant must be built where fresh materials are plentiful and reasonable in price. A diversity of products makes possible an operating season long enough to keep the overhead expenses down to the minimum. The products dried, however, should be limited to those for which a ready market exists. The only satisfactory method of operating is to contract for a sufficient acreage to take care of the needs of a plant at a price which will permit both the grower and the drier to make a profit. Material to be dried must be carefully sorted so as to be free of mould, decay and other defects that would lower the grade of the finished product. The stone fruits (apricots, peaches, cherries and plums) must be sufficiently firm to permit mechanical pitting without tearing. Where they are prepared by manual labour they must not be so soft as to stick to the trays. Apples and pears must not be so soft as to crush in the coring and peeling machines. Berries, cranberries and grapes are usually dried whole. Fruit that needs trimming must be avoided, as it not only adds to the cost of operation, but also lowers the grade of the final product. Vegetables, such as beans (snap), cabbage, carrots, celery, corn, parsnips, potatoes, pumpkin, spinach, squash and turnips, are sliced, shredded, diced or cut in desired pieces before drying. Dehydration does not improve the quality of fresh fruits or vegetables, nor does it provide for the satisfactory use of unsound products. At best the process can only conserve the original constituents of the foods, minus replaceable water. Careful handling reduces labour and waste. Bruised tissue is especially susceptible to discolouration and decay. Individual pieces prepared from good stock are more uniform and attractive than those from heavily trimmed stock. Raw materials should be as carefully washed and cleaned for dehydration as for table use. Much of the washing machinery used in canning is suitable for use in dehydration plants. A rotary cylindrical washer equipped with a water‐spraying system is very satisfactory for washing many types of products. Soft or easily broken fruits and vegetables may be washed by passing the trayed material between several sprays of cold water. The segregation of fresh fruits and vegetables according to size facilitates both the preparatory handling and the drying. One type of grader consists of a perforated metal plate, 3 by 10 feet, or larger. The perforations are in sections of varying size, and the plate is inclined and mechanically agitated in order to insure an even flow of the material in one direction. The product is separated according to size by being passed through the perforations. Perforated plates are also used in stacks. Several plates, each stamped with holes of a uniform size, the holes varying in size with each plate, are set one above the other, with 6 inches or more between plates. They are arranged so that the holes are progressively smaller from top to bottom. Another grader sorts out easily rolling materials according to diameter. As a mechanically driven cable rolls the materials along an opening that increases in width, the product falls through and is collected according to size. A grader based on the same principle passes the product down a chute the floor of which consists of rollers placed at increasingly greater distances apart. As the product rolls along the chute it is separated in progression according to size.