2,394 research outputs found
The inverse electromagnetic scattering problem in a piecewise homogeneous medium
This paper is concerned with the problem of scattering of time-harmonic
electromagnetic waves from an impenetrable obstacle in a piecewise homogeneous
medium. The well-posedness of the direct problem is established, employing the
integral equation method. Inspired by a novel idea developed by Hahner [11], we
prove that the penetrable interface between layers can be uniquely determined
from a knowledge of the electric far field pattern for incident plane waves.
Then, using the idea developed by Liu and Zhang [21], a new mixed reciprocity
relation is obtained and used to show that the impenetrable obstacle with its
physical property can also be recovered. Note that the wave numbers in the
corresponding medium may be different and therefore this work can be considered
as a generalization of the uniqueness result of [20].Comment: 19 pages, 2 figures, submitted for publicatio
Protecting Against the Harms of the Mistaken Utility Undercharge
First, Part I introduces the basic law concerning estoppel. Then, Part II discusses the application of estoppel doctrine to the collection of undercharges by public utilities. Next, Part III examines whether, even in situations where the utility may collect the undercharge, it may be prohibited from using service disconnection as a collection device. Part IV analyzes the right of a consumer to bring a counter-claim for damages resulting from a utility\u27s mistaken undercharge. Finally, Part V recommends the adoption of a new approach to the problem of the utility undercharge as it relates to low-income households
Discrimination As a Sword for the Poor: Use of an “Effects Test” in Public Utility Litigation
This Article looks at how the effects test might be applied in the utility area. Part I discusses the definition and application of the prohibition against discrimination in utility cases. Part II examines the use of an effects test in the non-utility context. Part III describes how such an analysis can be used in seeking to prove utility discrimination. Part IV provides illustrative uses of an effects test in customer service situations and reviews one particular case to determine if application of this test might have given rise to different results
"Oxide-free" tip for scanning tunneling microscopy
We report a new tip for scanning tunneling microscopy and a tip repair procedure that allows one to reproducibly obtain atomic images of highly oriented pyrolytic graphite with previously inoperable tips. The tips are shown to be relatively oxide-free and highly resistant to oxidation. The tips are fabricated with graphite by two distinct methods
GPU LSM: A Dynamic Dictionary Data Structure for the GPU
We develop a dynamic dictionary data structure for the GPU, supporting fast
insertions and deletions, based on the Log Structured Merge tree (LSM). Our
implementation on an NVIDIA K40c GPU has an average update (insertion or
deletion) rate of 225 M elements/s, 13.5x faster than merging items into a
sorted array. The GPU LSM supports the retrieval operations of lookup, count,
and range query operations with an average rate of 75 M, 32 M and 23 M
queries/s respectively. The trade-off for the dynamic updates is that the
sorted array is almost twice as fast on retrievals. We believe that our GPU LSM
is the first dynamic general-purpose dictionary data structure for the GPU.Comment: 11 pages, accepted to appear on the Proceedings of IEEE International
Parallel and Distributed Processing Symposium (IPDPS'18
Minimizers with discontinuous velocities for the electromagnetic variational method
The electromagnetic two-body problem has \emph{neutral differential delay}
equations of motion that, for generic boundary data, can have solutions with
\emph{discontinuous} derivatives. If one wants to use these neutral
differential delay equations with \emph{arbitrary} boundary data, solutions
with discontinuous derivatives must be expected and allowed. Surprisingly,
Wheeler-Feynman electrodynamics has a boundary value variational method for
which minimizer trajectories with discontinuous derivatives are also expected,
as we show here. The variational method defines continuous trajectories with
piecewise defined velocities and accelerations, and electromagnetic fields
defined \emph{by} the Euler-Lagrange equations \emph{% on} trajectory points.
Here we use the piecewise defined minimizers with the Li{\'{e}}nard-Wierchert
formulas to define generalized electromagnetic fields almost everywhere (but on
sets of points of zero measure where the advanced/retarded velocities and/or
accelerations are discontinuous). Along with this generalization we formulate
the \emph{generalized absorber hypothesis} that the far fields vanish
asymptotically \emph{almost everywhere%} and show that localized orbits with
far fields vanishing almost everywhere \emph{must} have discontinuous
velocities on sewing chains of breaking points. We give the general solution
for localized orbits with vanishing far fields by solving a (linear) neutral
differential delay equation for these far fields. We discuss the physics of
orbits with discontinuous derivatives stressing the differences to the
variational methods of classical mechanics and the existence of a spinorial
four-current associated with the generalized variational electrodynamics.Comment: corrected minor typo: piecewise differentiable on closed instead of
open interval
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