12,852 research outputs found
Re-evaluation of cosmic ray cutoff terminology
The study of cosmic ray access to locations inside the geomagnetic field has evolved in a manner that has led to some misunderstanding and misapplication of the terminology originally developed to describe particle access. This paper presents what is believed to be a useful set of definitions for cosmic ray cutoff terminology for use in theoretical and experimental cosmic ray studies
Reoptimization of Some Maximum Weight Induced Hereditary Subgraph Problems
The reoptimization issue studied in this paper can be described as follows: given an instance I of some problem Π, an optimal solution OPT for Π in I and an instance I′ resulting from a local perturbation of I that consists of insertions or removals of a small number of data, we wish to use OPT in order to solve Π in I', either optimally or by guaranteeing an approximation ratio better than that guaranteed by an ex nihilo computation and with running time better than that needed for such a computation. We use this setting in order to study weighted versions of several representatives of a broad class of problems known in the literature as maximum induced hereditary subgraph problems. The main problems studied are max independent set, max k-colorable subgraph and max split subgraph under vertex insertions and deletion
Optimal self-assembly of finite shapes at temperature 1 in 3D
Working in a three-dimensional variant of Winfree's abstract Tile Assembly
Model, we show that, for an arbitrary finite, connected shape , there is a tile set that uniquely self-assembles into a 3D
representation of a scaled-up version of at temperature 1 in 3D with
optimal program-size complexity (the "program-size complexity", also known as
"tile complexity", of a shape is the minimum number of tile types required to
uniquely self-assemble it). Moreover, our construction is "just barely" 3D in
the sense that it only places tiles in the and planes. Our
result is essentially a just-barely 3D temperature 1 simulation of a similar 2D
temperature 2 result by Soloveichik and Winfree (SICOMP 2007)
Scattering of first and second sound waves by quantum vorticity in superfluid Helium
We study the scattering of first and second sound waves by quantum vorticity
in superfluid Helium using two-fluid hydrodynamics. The vorticity of the
superfluid component and the sound interact because of the nonlinear character
of these equations. Explicit expressions for the scattered pressure and
temperature are worked out in a first Born approximation, and care is exercised
in delimiting the range of validity of the assumptions needed for this
approximation to hold. An incident second sound wave will partly convert into
first sound, and an incident first sound wave will partly convert into second
sound. General considerations show that most incident first sound converts into
second sound, but not the other way around. These considerations are validated
using a vortex dipole as an explicitely worked out example.Comment: 24 pages, Latex, to appear in Journal of Low Temperature Physic
Flake aligner including baffles supported on continuously moving conveyor
Apparatus for forming a continuous elongated loosely felted mat of thin elongated wood flakes with the flakes being aligned in mutually parallel interleaved relation. The apparatus includes a plurality of belts positioned in adjacent side-by-side relation and for continuous movement so as to define a supporting surface for the mat. A plurality of sets of thin planar baffle plates are provided, each set including a plurality of thin planar baffle plates supported in coplanar alignment and in edge-to-edge adjacent relation. The baffle plates are positioned between a hopper for depositing wood flakes and the supporting surface and function to align the wood flakes in substantially mutually parallel relation in substantially parallel relation to the direction of movement of the supporting surface and to maintain the wood flakes in substantially parallel alignment as the flakes fall from the hopper onto the supporting surface. Each of the sets of baffle plates are positioned between pairs of belts and are supported for movement with the belts, and the baffle plates of one set are parallel to and spaced closely adjacent to baffle plates of an adjacent set.https://digitalcommons.mtu.edu/patents/1119/thumbnail.jp
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