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This paper aims to determine the optimum arrangement of a reverse osmosis system in two methods of plug and concentrate recycling.

To compare the optimum conditions of these two methods, a seawater reverse osmosis system was considered to produce fresh water at a rate of 4,000 m3/d for Mahyarkala city, located in north of Iran, for a period of 20 years. Using genetic algorithms and two-objective optimization method, the reverse osmosis system was designed.

The results showed that exergy efficiency in optimum condition for concentrate recycling and plug methods was 82.6 and 92.4 per cent, respectively. The optimizations results showed that concentrate recycling method, despite a 36 per cent reduction in the initial cost and a 2 per cent increase in maintenance expenses, provides 6 per cent higher recovery and 19.7 per cent less permeate concentration than two-stage plug method.

Optimization parameters include feed water pressure, the rate of water return from the brine for concentrate recycling system, type of SW membrane, feedwater flow rate and numbers of elements in each pressure vessel (PV). These parameters were also compared to each other in terms of recovery (R) and freshwater unit production cost. In addition, the exergy of all elements was analyzed by selecting the optimal mode of each system.

A novel cost-effective bio-digester was explored to convert biological waste into useful clean energy. The bioreactor was aimed to anaerobically digest locally sourced cow dung and chicken droppings.

The design consideration is a batch horizontal 267 L digester made from cast iron with centrally positioned four-impeller shaft to enhance mixing. The system operated with a retention time of 63 days and a substrate (cow dung and poultry waste) ratio of 1:2 and water substrate ratio of 1:0.5 in the gasholder system. The purification, compression and performance evaluation of the generated biogas were also conducted.

The total volume of gas produced for each substrate compositions designed over 14 days ranges between 49.34 and 52.91 mL/day. The optimal value of 52.45 ml using cow dung and poultry waste (w/w) 20:80 was obtained. The average ambient temperatures during the study were within the mesophilic range of 20-40°C. The pH values were stable and always in the optimal range of 6.5-8.0. The reductions in moisture content, ash content, total solids and volatile solids were from 80.50-0.20 per cent, 39.60-14 per cent, 18.50-5.90 per cent and 11.60-4.90 per cent, respectively.

The developed digester is cost-effective and would help minimize solid waste disposal. The estimated methane contents of the gas from cow dung and chicken waste after scrubbing were found to be 71.95 per cent and could be harnessed in solving the energy crisis in the developing nations.

A Lecture Delivered by Mr. A. C. Lovesey to the de Havilland Aircraft Company Technical Department in November, 1945. SINCE the war ended a number of British and American technicians have visited Germany and nearly all come back with the same story—the story of that army of German scientists who have been working with super equipment—supersonic wind‐tunnels, high altitude plants—long term planning of most fantastic projects—and one is almost persuaded that we must have been a lot of amateurs in this country!

SOME THREE YEARS or so ago a statistical study of the British motor car population revealed that the average life of the individual vehicle was significantly longer than pre‐war. Several contributory factors were discussed. Firstly we apparently drive fewer miles a year than heretofore while the quality of engines and components such as tyres is much higher nowadays. We also note in the post‐war period that changes in vehicle design and greater mechanical efficiency have reduced the time spent on maintenance and at the same time made driving easier. Included here are long‐life plugs, ‘permanent’ anti‐freeze solutions, anti‐corrosive underseal, improved suspension and joints ‘packed‐for‐life’ with special quality grease. All these things might he regarded as indicative of a compensatory trend; as we drive less in our improved labour‐saving vehicles, road conditions become more uncomfortable and hazardous.

Do social movement organizations increase the supply of a public good? We address this question by investigating the role of generalist social movement organizations and technology-focused organizations for the development of the electric vehicle (EV) charging infrastructure in California from 1995 until 2012. We find that increases in the membership of Electric Auto Association (EAA) chapters in the cities of California enhanced the number of EV charging stations set up in each city. Our analyses also show that the organizational diversity of the environmental movement spurred the growth of EAA membership but did not directly increase the establishment of charging stations.

THE demands made on equipment for the modern aircraft have been commented on increasingly of recent years, and as with all that goes into aircraft, there is the perennial requirement for minimum weight. With this in mind magnesium‐zirconium alloys have been studied by Dowty Fuel Systems Ltd. for use in such components as the bodies of items of hydraulic equipment. Magnesium alloys in general are very light, having a specific gravity of about 1·8, which is not much more than that of such non‐metallic materials as glass fibre laminates, but their physical properties are rather low, and they are subject to corrosion. However, alloys containing zirconium, such as ZRE 1, are much less liable to micro‐porosity than other magnesium alloys, and have correspondingly improved mechanical properties, apart from the fact that porosity affects directly hydraulic equipment operating at the high pressures now common. In order to assess the suitability of this alloy for such applications a series of tests was carried out to check strength and freedom from porosity. Sand castings were obtained, of fairly large mass relative to the dimensions, the form being shown in FIG. 1. A number of bores were made so as to provide conditions similar to those in a functioning production unit, and porosity and strength checked by static pressure and pulsation tests. Details of the results are given below. Thread shear tests and tests on the use of circlips to retain plugs in the bores were also carried out.

CONCERN about the possible future of fuel supplies and the effect on fuel specifications was felt in the early 1970's, and since that time Dowty Fuel Systems has taken an active policy to ensure that hydromechanical components will be capable of handling aviation fuels which may be expected to appear in future years. A continuing programme of research is in existance which both monitors the trends in aviation fuels and develops controls which will satisfy future requirements.

The purpose of this paper is to estimate whether sexual activity is associated with wages, and also to estimate potential interactions between individuals’ characteristics, wages and sexual activity.

The central hypothesis behind this research is that sexual activity, alike health indicators and mental well-being, may be thought of as part of an individual’s set of productive traits that affect wages. Using two-stage estimations the author examines the relationship between adult sexual activity and wages.

The author estimates that there is a monotonic relationship between the frequency of sexual activity and wage returns, whilst the returns to sexual activity are higher for those between 26 and 50 years of age. In addition, heterosexuals’ sexual activity does not seem to provide higher or lower wage returns than that of homosexuals, but wages are higher for those health-impaired employees who are sexually active. Over-identification tests, robustness checks, falsification tests, as well as, decomposition analysis and sample selection modelling enhance study’s strength.

Contemporary social analysis suggests that health, cognitive and non-cognitive skills and personality are important factors that affect wage level. Sexual activity may also be of interest to social scientists, since sexual activity is considered to be a barometer for health, quality of life, well-being and happiness.

The paper adds to the literature on the importance of unobserved characteristics in determining labour market outcomes.

This paper aims to introduce a method to reduce corrosion caused by acidic-oxidized polymer degradant through subsection injection with different inhibitor.

This paper introduced a method to reduce corrosion caused by acidic-oxidized polymer degradant through subsection injection with different inhibitor.

The experimental results indicated that the influence of pre-corrosion status on corrosion rate and effectiveness of corrosion inhibitor are significant. The corrosion inhibitors in both injection stage inhibited the corrosion process by preventing the contact of corrosive medium and steel surface through formation of a protective film on the surface of N80 steel. The corrosion rate of polymer degradant can be reduced to 0.63 g/m 2 h through subsection injection with different inhibitor.

This result will increase the production of polymer injection plugging wells through expanding the application of acidic-oxidized polymer degradant.

The existing theoretical and empirical research on cultural impact is rather inconsistent. The purpose of this paper is to deal with the reasons for this inconsistency by debating the adequate inclusion of the cultural factor in the growth model and the way to properly measure cultural capital (CC) for this purpose.

The paper starts with analyzing the limitations of growth theory (in particular Paul Romer ' s endogenous growth model) when CC is not taken into consideration. The amelioration is suggested through involvement of the Weberian mechanism of cultural impact. The difference between Weber ' s mechanism and using religion as a measurement proxy for cultural attitudes is enlightened. The improvement of Weber ' s measurement of CC by elevating Pierre Bourdieu ' s approach to CC from individual to aggregate regional level is suggested. Real data from five EU countries on NUTS II level is addressed for illustrating the above reasoning.

The evidence shows that the suggested by the paper measurement strategy for CC allows for treating culture indeed as a single factor both in theoretical and econometrical sense of the term factor, but without loss of information, which is otherwise inevitable if the author try to approximate culture with a single mono-dimensional variable such as religion.

Through discussion on Rome ' s endogenous growth model and Weber ' s cultural mechanisms of impact, the amelioration of growth theory by inclusion of CC is explained, operationalized and applied on a real data example.