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The general theory of nuclear magnetic resonance ͑NMR͒ imaging of large electromagnetically active systems is considered. We emphasize particularly noninvasive geophysical applications such as the imaging of subsurface water content. We derive a general formula for the NMR response voltage, valid for arbitrary transmitter and receiver loop geometry and… (More)

- Peter B. Weichman, Dong Rong Lun, Michael H. Ritzwoller, Eugene M. Lavely
- 2002

Motivated by the recent application of the Earth-field nuclear magnetic resonance (NMR) technique to the detection and mapping of subsurface groundwater (to depths of 100 m or so), and making use of a recently developed theory of the method, we consider in detail the resulting inverse problem, namely the inference of the subsurface water distribution from a… (More)

We review a striking array of recent experiments and their theoretical interpretations on the superfluid transition in 4 He in the presence of a heat flux Q. We define and evaluate a new set of critical point exponents. The statics and dynamics of the superfluid-normal interface are discussed, with special attention to the role of gravity. If Q is in the… (More)

A concise, 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… (More)

The general theory of surface NMR imaging of large electromagnetically active systems is considered, motivated by geophysical applications. A general imaging equation is derived for the NMR voltage response, valid for arbitrary transmitter and receiver loop geometry and arbitrary conductivity structure of the sample. When the conductivity grows to the point… (More)

We review a striking array of recent experiments, and their theoretical interpretations, on the superfluid transition in 4 He in the presence of a heat flux, Q. We define and evaluate a new set of critical point exponents. The statics and dynamics of the superfluid-normal interface are discussed, with special attention to the role of gravity. If Q is in the… (More)

- Peter B. Weichman
- IEEE Trans. Geoscience and Remote Sensing
- 2013

- Peter B. Weichman
- 2011 4th IEEE International Workshop on…
- 2011

This paper reviews some recent physics-based modeling approaches in support of microwave through-wall building tomography. Building layout estimation is a nonlinear inverse problem with a large number of degrees of freedom (geometry, location, and scattering properties of major building elements, such as walls, floors, and ceilings, plus many other smaller… (More)

Uncertainties in Source Speciic Station Corrections SSSCs arise from several sources. If the SSSCs are constructed directly from empirical travel times, there are errors caused by origin time and hypocenter location errors, measurement errors, and phase misidentiication. If a 3-D model is used either to interpolate an empirical surface or to compute the… (More)

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