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Papers by Michael Brown

Journal of Geophysical Research: Solid Earth, 2020

Existing amplitude variation with offset (AVO) and slowness (AVS) theories fail to interpret obse... more Existing amplitude variation with offset (AVO) and slowness (AVS) theories fail to interpret observed amplitudes in terms of actual elastic properties of the media for a reflection event resulting from a stack of thin layers. We propose a method to replace the stack of thin layers with an equivalent medium of elastic properties using the Backus averaging theory. Numerical examples show considerable deviation in intercept calculated from the modified AVO and AVS theories from the conventional methods. AVS theory is preferred as it can be applied irrespective of impedance contrast in both precritical and postcritical reflections, and no spherical divergence correction is required. P and S wave velocities, density, and thickness of thin layers are determined using the inversion scheme of very fast simulated annealing (VFSA). Uncertainty in prediction is evaluated using an approximate marginal posterior probability density function and a parameter correlation matrix. We demonstrate our methodology on synthetic and real seismic data from the Sleipner field, which is a good example of enhanced seismic amplitudes due to interference among reflections from thin layers. We select 11 common depth point (CDP) gathers for amplitude analysis of four identified reflectors along a line of 3‐D seismic data acquired in 2008. Predicted mean models of CO2‐saturated sand layers at all locations show that the thickness, density, and P and S wave velocities vary from 5–7 m, 1.8–2.0 g/cm3, and 1,460–1,490 and 630–650 m/s, respectively. Our analysis suggests that the model parameters are well constrained and independent except at a few locations.

Physical Modelling in Geotechnics

AIP Conference Proceedings, 2003

More than half of the approximately 360 Lyman-alpha emitters found by the LALA survey show rest e... more More than half of the approximately 360 Lyman-alpha emitters found by the LALA survey show rest equivalent widths (EWs) larger than 200 Å, which is the maximum EW expected for normal stellar population. The high EWs can be reproduced by stellar populations with high proportions of young, massive stars, or by type 2 AGNs, which are supposed to be detectable

We test a Monte Carlo simulation of particle collisions based on a model by Takizuka and Abe [JCP... more We test a Monte Carlo simulation of particle collisions based on a model by Takizuka and Abe [JCP 25, 205, (1977)]. This model is included in the Hamiltonian particle pushing code (PPC) for simulating particle orbits in the Swarthmore Spheromak eXperiment (SSX) MHD wind tunnel. The simulated dynamics, with collisions, are compared with analytical transport equations for slowing down, diffusion, and energy loss. Preliminary results show general agreement with the analytic model. The Takizuka collision model performs binary collisions between the test particle and a field particle drawn from a stationary Maxwellian background distribution of ions. The time difference between collisions is dependent on the current plasma parameters. Realistic particle dynamics in simulated SSX wind tunnel fields will be presented if available.

Process Safety and Environmental Protection, 2001

Revista Brasileira de Cirurgia Cardiovascular, 2009

2012 IEEE International Conference on Green Computing and Communications, 2012

Lecture Notes in Computer Science, 2014

Political Geography, 2005

Political Geography, 2006

Magnetic Resonance Imaging, 1991

The Journal of the Acoustical Society of America, 2008

ABSTRACT The importance of resonantforward scattering of sound by highly directional large amplit... more ABSTRACT The importance of resonantforward scattering of sound by highly directional large amplitude nonlinear internal waves in shallow water environments has been well established. In contrast, most deep ocean environments are characterized by the presence of a sound speed perturbation (due mostly to internal waves) whose horizontal wave number spectrum is broad and approximately horizontally isotropic; under such conditions, the importance of resonantforward scattering is less clear. Exceptional deep ocean conditions are found in the vicinity of submarine ridges, which serve to generate internal tides that are both highly directional and have a narrow horizontal wave number spectrum. In this talk, ray, mode, and PE simulations are presented to explore the importance of resonantforward scattering by such structures under fairly realistic oceanographic conditions. [Work supported by ONR.]

Journal of Pharmaceutical Sciences, 1973

Several new experimental results are reported from plasma merging studies at the Swarthmore Spher... more Several new experimental results are reported from plasma merging studies at the Swarthmore Spheromak Experiment (SSX) with relevance to three dimensional magnetic reconnection in laboratory and space plasmas. First, recent high-resolution velocity measurements of impurity ions using ion Doppler spectroscopy (IDS) show bi- directional outflow jets at 40 km/s (nearly the Alfv'en speed). Second, ion heating to nearly 10^6 K is observed after reconnection events in a low density regime. Third, the out-of-plane magnetic field in a reconnection volume shows a quadrupolar structure at the ion inertial scale (c/phipi). Time resolved vector magnetic field measurements on a 3D lattice (B(r, t)) enables this measurement. Each of these measurements will be related to and compared with similar observations in a solar or space context.

Journal of Metamorphic Geology, 1985

Journal of Folklore Research: An International Journal of Folklore and Ethnomusicology, 2007

Page 1. "Earnest Spade Work": The New Zealand Folklore Society, 1966-1975 Micha... more Page 1. "Earnest Spade Work": The New Zealand Folklore Society, 1966-1975 Michael Brown Abstract: The New Zealand Folklore Society was a small organisation that emerged from the folk revival scene in Wellington, New Zealand, in 1966. ...

Environment and Planning D: Society and Space, 2003

Critical perspectives on space and spatiality have been underdeveloped theoretically and underapp... more Critical perspectives on space and spatiality have been underdeveloped theoretically and underapplied empirically in the context of queer studies (including queer theory). In this paper we demonstrate how critical perspectives on one form of spatiality, diffusion, can enhance understandings of queer cultures, identities, and politics. We begin by reviewing traditional approaches to diffusion within geography and explicating a specifically queer approach to the topic. Our approach builds on existing critical perspectives and certain principles of structurationism. We then apply this approach to our empirical research and activism in two very different locales: Duluth, Minnesota, and Seattle, Washington. In so doing we illustrate the complex and nuanced spatialities of heteronormative power and resistances to it.