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An overview is presented of several diverse branches of work in the area of effectively 2D fluid equilibria which have in common that they are constrained by an infinite number of conservation laws. Broad concepts, and the enormous variety of physical phenomena that can be explored, are highlighted. These span, roughly in order of increasing complexity, Euler flow, nonlinear Rossby waves, 3D axisymmetric flow, shallow water dynamics, and 2D magnetohydrodynamics. The classical field theories describing these systems bear some resemblance to perhaps more familiar fluctuating membrane and continuous spin models, but the fluid physics drives these models into unconventional regimes exhibiting large scale jet and eddy structures. From a dynamical point of view these structures are the end result of various conserved variable forward and inverse cascades. The resulting balance between large scale structure and small scale fluctuations is controlled by the competition between energy and entropy in the system free energy, in turn highly tunable through setting the values of the conserved integrals. Although the statistical mechanical description of such systems is fully self-consistent, with remarkable mathematical structure and diversity of solutions, great care must be taken because the underlying assumptions, especially ergodicity, can be violated or at minimum lead to exceedingly long equilibration times. Generalization of the theory to include weak driving and dissipation (e.g., non-equilibrium statistical mechanics and associated linear response formalism) could provide additional insights, but has yet to be properly explored. [ABSTRACT FROM AUTHOR]

This study identifies general characteristics of methods to estimate the absolute range between an acoustic transmitter and a receiver in the deep ocean. The data are from three days of the PhilSea10 experiment with a single fixed transmitter depth (∼998 m) and 150 receiver depths (∼210–5388 m) of known location, and a great-circle transmitter-receiver distance of ∼510 km. The proposed ranging methods compare observed acoustic records with synthetic records computed through the HYCOM (hybrid coordinate ocean model) model. More than 8900 transmissions over 3 days characterize the statistical variation of range errors. Reliable ranging methods de-emphasize the parts of the data records least likely to be reproduced by the synthetics, which include arrival amplitudes, the later parts of the acoustic records composed of nearly horizontally launched rays (i.e., the finale), and waves that sample a narrow span of ocean depths. The ranging methods proposed normalize amplitudes, measure travel times, or reject parts of the waveforms beyond a critical time. All deliver reliable range estimates based on the time and path-averaged HYCOM model, although the final method performs best. The principles behind these methods are transportable and expected to provide reliable range estimates in different deep water settings. [ABSTRACT FROM AUTHOR]

The work reported here details basic validation of our advanced physics-based electromagnetic induction forward and inverse models against data collected by the Naval Research Laboratory Time-Domain Electromagnetic Multisensor Towed Array Detection System platform. The data were collected under laboratory-type conditions using both artificial spheroidal targets and real unexploded ordnance (UXO). The artificial target models are essentially exact and enable detailed comparison of theory and data in support of measurement platform characterization and target identification. Real UXO targets cannot be treated exactly, but it is demonstrated that quantitative comparisons of the data with the spheroid models nevertheless aid in extracting key target discrimination information, such as target geometry and hollow target shell thickness. [ABSTRACT FROM AUTHOR]

A concise and somewhat personal review of the problem of superfluidity and quantum criticality in regular and disordered interacting Bose systems is given, concentrating on general features and important symmetries that are exhibited in different parts of the phase diagram, and that govern the different possible types of critical behavior. A number of exact results for various insulating phase boundaries, which may be used to constrain the results of numerical simulations, can be derived using large rare region type arguments. The nature of the insulator-superfluid transition is explored through general scaling arguments, exact model calculations in one dimension, numerical results in two dimensions, and approximate renormalization group results in higher dimensions. Experiments on 4He adsorbed in porous Vycor glass, on thin film superconductors, and magnetically trapped atomic vapors in a periodic optical potential are used to illustrate many of the concepts. [ABSTRACT FROM AUTHOR]