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It is not normally possible to heat a static steel work‐piece past the Curie temperature without incurring reduced inverter utilisation. Since the inverter cost increases with rated power, reduced utilisation implies an increase in investment costs for a given performance. The paper shows that third‐order resonant work‐head circuits can intrinsically allow better utilisation of the inverter for variable‐load heating operations. A further refinement is then shown to allow control of the load impedance, thereby allowing the utilisation to approach 100 percent over the heating cycles.

IN DECEMBER 1969, I reviewed for the Library world the library literature of the 1960s'. I remember hoping, when I wrote that I might have the chance to perform a similar office for the library literature of the 1970s. The opportunity has come. But note: I have not used it to nominate the best publications of the decade. I would certainly like to think that I knew the best, and therefore also the worst, when I saw them, but after a swift reconnaissance of the decade's offerings I was appalled at what I had missed. There was a time when I could recite the names of every British librarian who had published at least one book on librarianship, and a fair number of American librarians besides. Who could do it now? Who would want to?

The purpose of this paper is to analyze the performance of LCLC resonant converter (RC) with proportional integral controller and fuzzy gain scheduled proportional integral controller.

The drawbacks of series RC and parallel resonant converter (PRC) are explained using relevant references in Section 1 of this paper. The necessity of RCs and the merits of zero voltage and zero current switching are given in the Section 2. In Section 3, the modeling of LCLC RC using state space technique is done. In Section 4, the open loop analysis and performance evaluation of proportional integral controller, fuzzy gain scheduled proportional controller using MATLAB Simulink is obtained. The hardware specification is given and experimental results are taken for LCLC RC. In Section 5, conclusion of study is given.

The LCLC RC overcomes the drawbacks of series and PRC. The fuzzy gain scheduled proportional integral controller is suitable for load variations in RC.

The output of the converter is not affected with the load variations since the controller suggested in the paper works for load changes and can be a solution for load parameter deviation applications. Also performance of the RC is improved by the fast response of the proposed controller.

Many electric circuits feature some type of non-linearity of their used devices. Non-linear resistors or inductors could be typical examples. Also, all semiconductor devices are in their nature non-linear ones. The simulation models are very important parts of the design of the devices in various fields of industry. Multiply (multiple) simulation, verified by the measurement on the physical sample, help to improve the converter design by understanding the current and voltage behavior of non-linear elements. The paper aims to discuss these issues.

Mathematical model of LCTLC inverter was made. Fictitious exciting function was applied on LCTLC inverter model. The non-linear inductance with the real core EFD model has been created and consequentially used for MatLab simulation experiments. MatLab and OrCAD/PSpice simulation results were compared with experimental measurements carried out on physical sample.

The authors have found how to simulate non-linear resonant circuits within mathematical apparatus using fictitious exciting function method. The authors provided comparisons between proposed simulation mathematical model and relevant physical sample. Multiply simulations can help to improve the converter design by understanding the current and voltage behavior of non-linear elements.

The proposed method is applicable for simulation purposes. The only limitation is that MatLab model does not include hysteresis curve of the core, therefore it has to be modeled.

The design of power supplies (switched mode power supplies, UPS and resonant inverter).

Research in the area of behaviors of non-linear components in resonant circuits.

NEWS of the next Anglo‐Scandinavian Library Conference to be held in Denmark from Sept. 28th to Oct. 1st, 1961, has just reached us, though at the time of writing we have no details of the precise venue or of the programme. As many of our readers will remember, the first of these Conferences took place at Halmstad in Sweden in 1953, and another was held at York in 1958. We can be certain that our Danish colleagues will this year prepare an interesting programme in the conference hall, and will supplement it by visits to some of their newer libraries. In this respect they have much to show, for in addition to the impressive main library of the Copenhagen city system, and the delightful library at Hørsholm, both of which have been seen by touring librarians from Britain, we have news of even more recent buildings at Horsens, Køge, Møn and other places. The new State Library at the University of Aarhus, now in course of erection, may not be finished at the time of the Conference, but it would still be worth visiting, even if it is not included in the official programme. Danish hospitality is world‐famous, and those British librarians who can afford to make the trip will find it rewarding in every way.

The term coaching comes from the sports field, where an experienced and knowledgeable player watches the way the less‐skilled batsman or golfer makes his shots, and suggests ways of improvement — ‘Keep your eyes on the ball, use your wrists’ and so on. Increasingly the development of subordinates is seen as a major responsibility of managers. But what is accepted in principle is found to be very difficult to practise in the day‐to‐day pressures of industrial life, because it involves the interactions of people with each other. This article takes a typical make or break situation. Built on a case‐study, it shows how a deputy, who might have been passed over, becomes the man ready to take the place of his promoted boss.

The German Iron and Steel Institute in Düsseldorf invited me to spend three weeks visiting technical information services on the Continent. Three aims were kept in view: to examine methods of operating information services, to study the attitude of industrial management and research toward technical information, to contact some of the leading people in the technical information field in Western Europe. Twenty‐two technical information organizations are described.

This article follows on an investigation conducted by the Unit for Library and Information Research of the Human Sciences Research Council in 1981 for the Department of National Education. The article is limited to a consideration of the aim and functions of national library services. Matters such as the organisation and management of these services, the pros and cons of centralisation and decentralisation in particular circumstances, bringing services into line with modern demands, problem areas in existing services, the raison d'être of national library and information advisory councils alongside the management councils of national library services, legislation of these services, etc. have been excluded from the discussion.

This study investigates national trends in students’ science, technology, engineering, and mathematics (STEM) occupational expectations by using Program for International Student Assessment (PISA) 2000, 2003, and 2006 data. The analyses in this study revealed several noteworthy national trends in STEM occupational expectations. In many countries students’ computing or engineering (CE) occupational expectations changed between PISA 2000 and PISA 2006, while students’ health service (HS) occupational expectations remained constant. In particular, many developed countries experienced downward national trends in CE occupational expectations among top performers in science. This study also found gender differences in national trends in STEM occupational expectations. In many countries boys’ CE occupational expectations decreased between PISA 2000 and PISA 2006, while girls’ occupational expectations remained unchanged in both CE and HS fields. Finally, the gender gaps in CE occupational expectations converged in many countries, but this convergence was not due to increases in CE occupational expectations among girls, but rather decreases in expectations among boys. Because one of the policy goals in many countries is to promote engagement in STEM education and occupations among students, especially academically talented students, the current findings – national declines in CE occupational expectations among top academic performers – will most likely be viewed as problematic in several countries. Future research should use data collected over longer periods to investigate whether students’ interest in STEM education and occupations increased or decreased in a variety of countries, and whether these patterns varied by student characteristics and performance levels. Moreover, future research must focus on factors that can explain the national trends in student interest in STEM education and occupations.

This study examines the educational aspirations of immigrant students, who are descendants of eight different immigrant communities in Germany. First, the article shows that compared to native German students, the educational aspirations of students with migration origin vary substantially. Challenging previous narratives of immigrant optimism and information deficit, the article suggests that the students of Turkish origin develop a conscious appraisal of obtaining an academic high-school qualification (AHSQ), even if they realize they will not be able to receive one by the end of the high-school. The study also shows that the duration of their stay in Germany plays a significant role in attenuating the high educational aspirations of most immigrant communities. However, Turkish students constitute an exception to this finding as they maintain high idealistic aspirations from first- to third-generation. The return migrant students from the former Soviet Union are the only group who report high educational aspirations, when asked about both their idealistic and realistic aspirations. Finally, the findings indicate that the position of the particular immigrant groups within the German social status hierarchy is a strong determinant of the educational aspirations of immigrant students and their parents.