Three-dimensional acoustic propagation through shallow water internal, surface gravity and bottom sediment waves

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2011This thesis describes the physics of fully three-dimensional low frequency acoustic interaction with internal waves, bottom sediment waves and surface swell waves that are often observed in shallow waters and on continental slopes. A simple idealized model of the ocean waveguide is used to analytically study the properties of acoustic normal modes and their perturbations due to waves of each type. The combined approach of a semi-quantitative study based on the geometrical acoustics approximation and on fully three-dimensional coupled mode numerical modeling is used to examine the azimuthal dependence of sound wave horizontal reflection from, transmission through and ducting between straight parallel waves of each type. The impact of the natural crossings of nonlinear internal waves on horizontally ducted sound energy is studied theoretically and modeled numerically using a three-dimensional parabolic equation acoustic propagation code. A realistic sea surface elevation is synthesized from the directional spectrum of long swells and used for three-dimensional numerical modeling of acoustic propagation. As a result, considerable normal mode amplitude scintillations were observed and shown to be strongly dependent on horizontal azimuth, range and mode number. Full field numerical modeling of low frequency sound propagation through large sand waves located on a sloped bottom was performed using the high resolution bathymetry of the mouth of San Francisco Bay. Very strong acoustic ducting is shown to steer acoustic energy beams along the sand wave’s curved crests.Office of Naval Research for the financial support of this work

«ОБЩЕСТВО ИСТРЕБЛЕНИЯ БОГАТСТВ» В ТВОРЧЕСТВЕ ЖОРЖА БАТАЯ

This article examines Georges Bataille's interpretation of the tribes of northwestern America (Indians), ancient Mexico (Aztecs), and similar archaic cultures as examples of a «society of the extermination of wealth». The reasoning is based on the analysis of such a basic binary opposition in the philosophy of the French writer as the profane «order of things» and the sacred «intimate order», moving later to the interpretation of sacrifice and potlatch as useless «unproductive waste». Special attention is paid to the second ritual practice, which, according to Bataille, most clearly shows the fact that wealth in archaic society is understood in connection with waste, and not with the accumulation and multiplication of goods, which is already characteristic of capitalism. The author, based on primary sources, as well as domestic and foreign interpretive literature, connects the useless waste of surplus production in the «society of the extermination of wealth» with Bataille's interpretation of glory as likening the immensity of the sun and his idea that the ultimate goal of any flow of energy is annihilation. In the finale of the work, a comparison is made between capitalism and the «society of the extermination of wealth».The article is of interest to readers interested in twentieth-century French philosophy, archaic cultures, social anthropology.Данная статья посвящена рассмотрению принадлежащей Жоржу Батаю интерпретации племен Северо-западной Америки (индейцы), древней Мексики (ацтеки) и подобных им архаических культур в качестве примеров «общества истребления богатств». Рассуждение отталкивается от анализа такой основной бинарной оппозиции в философии французского писателя, как профанный «порядок вещей» и сакральный «сокровенный порядок», переходя впоследствии к толкованию жертвоприношения и потлача как бесполезных «непроизводительных трат». Особое внимание уделяется второй ритуальной практике, в которой, согласно Батаю, наиболее отчетливо проявляется тот факт, что богатство в архаическом обществе понимается в связи с расточительством, а не с накоплением и преумножением благ, что уже свойственно капитализму. Автор, основываясь на первоисточниках, а также отечественной и зарубежной интерпретаторской литературе, связывает бесполезную растрату излишков производства в «обществе истребления богатств» с интерпретацией Батаем  славы как уподобления безмерности солнца и его идеей, что конечной целью любого потока энергии является аннигиляция. В финале же работы производится сравнение капитализма с «обществом истребления богатств».Статья представляет интерес для читателей, интересующихся французской философией двадцатого века, архаическими культурами и социальной антропологией

Hybrid MHD/PIC simulation of a metallic gas-puff z pinch implosion

We present the hybrid MHD/PIC simulations of the time evolution of a bismuth metallic gas-puff z pinch in external axial magnetic field (AMF). Recent experiments with IMRI-5 generator (450 kA, 450 ns) [1] show the certain effect of an axial magnetic field on radiation energy produced during z pinch implosion. In order to perform the numerical simulation of gas puff z pinch a hybrid model was developed. The hybrid model treats the electrons as a massless fluid and ions as macroparticles. The macroparticle dynamic is calculated with the use of PIC method. Ion-ion Coulomb collision is considered with the use of MC method. The radiation transfer of bismuth plasma was accounted in the framework of P1 method. The interelectrode gap pumping by plasma of 8 μs 80 kA bismuth arc with the following plasma implosion by 450 kA / 450 ns current pulse in different external AMF was modelled. The obtained results are in a reasonable agreement with the experimental results. © Published under licence by IOP Publishing Ltd.The work was supported by Russian Science Foundation (project No. 16-19-10142)