This text is about methods used for the computer simulation of analog systems. It concentrates on electronic applications, but many of the methods are applicable to other engineering problems as well. This revised edition (1st, 1983) encompasses recent theoretical developments and program-writing tips for computer-aided design. About 60% of the text is suitable for a senior-level course in circuit theory. The whole text is suitable for graduate courses or as a reference for scientists and engineers who seek information in the field. Annotation copyright by Book News, Inc., Portland, OR

Advancements in science and engineering have occurred at a surprisingly rapid pace since the release of the seventh edition of this encyclopedia. Large portions of the reference have required comprehensive rewriting and new illustrations. Scores of new topics have been included to create this thoroughly updated eighth edition. The appearance of this new edition in 1994 marks the continuation of a tradition commenced well over a half-century ago in 1938 Van Nostrand's Scientific Encyclopedia, First Edition, was published and welcomed by educators worldwide at a time when what we know today as modern science was just getting underway. The early encyclopedia was well received by students and educators alike during a critical time span when science became established as a major factor in shaping the progress and economy of individual nations and at the global level. A vital need existed for a permanent science reference that could be updated periodically and made conveniently available to audiences that numbered in the millions. The pioneering VNSE met these criteria and continues today as a reliable technical information source for making private and public decisions that present a backdrop of technical alternatives.

From areport by a Lieutenant Colonel W.A. Ross (Chern. News, Nov.15, 1878, p. 236). Progress did not accelerate during the next 50 years. McBain, in his clas sic 1932 book, The Sorption oi Gases by So lids, devoted a chapter to sorp tion by chabasite, other zeolites, and permeable crystals. McBain remarked that "great interest attaches to the finding of Weigel and Steinhoff [0. Weigel and E. Steinhoff, Z. Kris!., 61, 125 (1925{raquo}) that chabasite rapidly sorbs the vapors of water, methyl and ethyl alcohol and formie acid, whereas acetone, ether and benzene are largely excluded. The significance of their results was pointed out by McBain [J.W. McBain, Colloid. Syrnp. Mon., 20, 1 (1926{raquo}) and recognized by alliater writers. It is evident that the partially dehydrated chabasite forms a nearly perfect molecular sieve or a semipermeable membrane of extremely regular structure ... ". While the significance of the above observation may have been recog nized, it had little impact. Thus, an eminent pioneer in the synthesis and characterization af zeolites, Professor R.M. Barrer, spent nearly two dec ades (following his Ph. D. studies in the 1930s) developing a firm foundation for the rapid growth in scientific understanding and industrial applications of zeolites which has taken place during the last 30 years.

As each area of technology with a potential for significantly impacting any major segment of the electronics industry evolves, it often is accompanied by the development of a succession of new circuits. Each new circuit indeed appears different, employing different components in differing configurations, and claims an assortment of distinct features of "improved performance. " Without a considerable investment of laboratory time to construct, evaluate, and compare each candidate circuit, it usually is difficult to realistically appraise the relative merits of one approach over another. It often is even more difficult to identify the underlying principles which point up basic similarities and differences. Such is the situation in the new and rapidly expanding area known as electronic power processing or switching mode power supplies. The area of switching power supplies has been spurred by the need for power sources of higher performance, smaller volume, and lighter weight in order to achieve compatibility with the shrinking size of all forms of communication and data handling systems, and particularly with the portable battery-operated equipment in everything from horne appliances and handtools to mobile com munication equipment. Static dc-to-dc converters and dc-to-ac inverters provide a natural interface with the new direct energy sources such as solar cells, fuel cells, thermoelectric generators, and the like, and form the central ingredient in most uninterruptable power sources.