General Bulletin


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Bulletin


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Fans and Ventilation


Book Description

The practical reference book and guide to fans, ventilation and ancillary equipment with a comprehensive buyers' guide to worldwide manufacturers and suppliers. Bill Cory, well-known throughout the fans and ventilation industry, has produced a comprehensive, practical reference with a broad scope: types of fans, how and why they work, ductwork, performance standards, testing, stressing, shafts and bearings. With advances in technology, manufacturers have had to continually improve the performance and efficiency of fans and ventilation systems; as a result, improvements that once seemed impossible have been achieved. Systems now range in all sizes, shapes, and weight, to match the ever increasing applications. An important reference in the wake of continuing harmonisation of standards throughout the European Union and the progression of National and International standards. The Handbook of Fans and Ventilation is a welcome aid to both mechanical and electrical engineers. This book will help you to... •Understand how and why fans work •Choose the appropriate fan for the right job, helping to save time and money •Learn installation, operational and maintenance techniques to keep your fans in perfect working order •Discover special fans for your unique requirements •Source the most appropriate equipment manufacturers for your individual needs - Helps you select, install, operate and maintain the appropriate fan for your application, to help you save time and money - Use as a reference tool, course-book, supplier guide or as a fan/ventilation selection system - Contains a guide to manufacturers and suppliers of ventilation systems, organised according to their different styles and basic principles of operation







Legislative Document


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Theory and Practice of Direct Methods in Crystallography


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Direct methods of crystal structure determination are usually associated with techniques in which phases for a set of structure factors are determined from the corresponding experimental amplitudes by probabilistic calcula tions. It is thus implied that such ab initio phase calculations do not require a knowledge of atomic positions, and this basis distinguishes direct methods from other techniques for structure determination. An acceptably wider interpretation of the term direct methods leads to other important applica tions involving, inter alia, the use of heavy atoms, resolution-limited phase data for large molecules, rotation functions, and Fourier series. These topics are discussed in the later chapters of this book. Although some earlier theoretical investigations were made by Harker and Kaspar, direct methods may be considered to have begun around the year 1950. Important landmarks in the development of the subject include the book by Hauptmann and Karle, The Centrosymmetric Crystal (1953), the definitive paper by Karle and Karle in Acta Crystallographica (1966), and the recent (1978) sophisticated program package MULTAN 78 produced mainly by Germain, Main, and Woolfson. Woolfson's book, Direct Methods in Crystallography, was published in 1961, but because of the rapid progress in direct methods, much of it soon became outmoded. It is interesting to note that direct methods nearly came into being many years earlier. Certainly the E2 relationship was used implicitly by Lonsdale in 1928 in determining the crystal structure of hexamethylbenzene.