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Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the worlds oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume the authors, all of whom have extensive at-sea experience in US and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.
Russian academic journal in the field of acoustics. The journal publishes scientific reviews, original papers, short communications, letters to the editor and current events. It covers theoretical and experimental aspects of physical, technical, and biological acoustics. This journal presents results of research conducted at the institutes of the Russian Academy of Sciences, and at universities and research establishments in Russia and abroad.
Seafloor investigation has long been a feature of not only seismology but also of acoustics. Indeed it was acoustics that produced depth sounders, giving us the first capability of producing both global and local maps of the seafloor. Subsequently, better instrumentation and techniques led to a clearer, more quantitative picture of the seabed itself, which stimulated new hypotheses such as seafloor spreading through the availability of more reliable data on sediment thickness over ocean basins and other bottom features. Geologists and geophysicists have used both acoustic and seismic methods to study the seabed by considering the propagation of signals arising from both natural seismic events and man-made impulsive sources. Although significant advances have been made in instrumentation, such as long towed geophysical arrays, ai r guns and ocean bot tom seismometers, the pic ture of the seafloor is still far from complete. Underwater acoustics concerns itself today with the phenomena of propagation and noise at frequencies and ranges that require an understanding of acoustic interaction at both of its boundaries, the sea surface and seafloor, over depths ranging from tens to thousands of meters. Much of the earlier higher frequency (>1 kHz) work included the characterization of the seafloor in regimes of reflection coefficients which were empirically derived from surveys. The results of these studies met with only limited success, confined as they were to those areas where survey data existed and lacking a physical understanding of the processes of reflection and scattering.
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 39 (thesis year 1994) a total of 13,953 thesis titles from 21 Canadian and 159 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 39 reports theses submitted in 1994, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
The Workshop on Hybrid Formulations of Wave Propagat~on and Scattering underwent a sequence of iterations before emerging in the format recorded here. These iterations were caused by various administrative and logistical problems which need not be detailed. However, its direction being set initially, the iterations led to modifications of the original concept so that the final form was arrived at through an indirect approach. This circumstance may ex plain some possible deficiencies which might have been removed, had the final concept been implemented directly. The motivation arose from a perception that the newly restored interest, coupled with new developments, in hybrid methods employ ing progressing wave fields and oscillatory wave fields for time harmonic and transient guided propagation in manmade or general geo physical environments, and for scattering by targets and irregulari ties, merits exposure to the wider scientific community. Accord ingly, a meeting with highly tutorial content was envisaged. For administrative reasons, related to sponsorship and organizational structure, this objective could not be realized but, eventually, there emerged the possibility of convening an Advanced Research Workshop (ARW) under the auspices of the NATO Advanced Study Insti tute Series. The original concept was then modified to accommodate a Workshop, wherein state-of-the-art science is discussed by a relatively small group of specialists, instead of tutorial presenta tions of more basic material.
ZENG Cheng-kui (C. K. TSENG) Research Professor; Director Emeritus illStitllte of Oceanology, Academia Sillica Qillgdao 26607 J, China Ten years ago I was invited by Professor John Steele, Director of the Woods Hole Oceanographic Institute of the U. S. A. to write a preface for the special issue on "Oceanography in China" for the Oceanus. I was then the Director of the Institute of Oceanology, Academia Sinica. I gladly appreciated the honor, and in the preface I briefly enumerated the history of oceanology, or oceanography according to the American custom, in China dividing it into four stages: the founding stage 1950-1956, the growing stage 1956-1964, the partial expanding stage 1965-1978, and the elevation stage since 1978 (Tseng, 1983/84). The founding stage of Chinese oceanofogy should actually start in 1931 with the establishment of the short-life Chinese Marine Biological Association in old China. The following twenty years in Chinese history between 1931 and 1959 comprised a very memorable period in China, badly marked by the World War II, and the 1946-1950 civil war. Some scattered research in marine biology was conducted in phycology, invertebrate zoology and ichthyology, mostly in taxonomy. A little work was devoted to delta geology and tidal and seawater temperature records. Two expeditions were organized and sent by the National Central Academy of Sciences to the Bohai Sea in 1935 and by the Beijing Academy of Sciences to the Jiaozhou Bay in 1936, both engaged principally in marine biological research.