5,317 research outputs found
A Robust Low-Complexity MIMO Detector for Rank 4 LTE/LTE-A Systems
This paper deals with MIMO detection for rank 4 LTE systems. The paper
revolves around a previously known detector [1, by Inkyu Lee, TCOM'2010] which
we shall refer to as RCSMLD
(Reduced-Constellation-Size-Maximum-Likelihood-Detector). However, a direct
application of the scheme in [1, by Inkyu Lee, TCOM'2010] to LTE/LTE-A rank 4
test cases results in unsatisfactory performance. The first contribution of the
paper is to introduce several modifications that can jointly be applied to the
basic RCSMLD scheme which, taken together, result in excellent performance. Our
second contribution is the development of a highly efficient hardware structure
for RCSMLD that allows for an implementation with very few multiplications.Comment: Accepted for publication in PIMRC-2014, Washington DC, US
From an axiological standpoint
I maintain that intrinsic value is the fundamental concept of axiology. Many contemporary philosophers disagree; they say the proper object of value theory is final value. I examine three accounts of the nature of final value: the first claims that final value is non‐instrumental value; the second claims that final value is the value a thing has as an end; the third claims that final value is ultimate or non‐derivative value. In each case, I argue that the concept of final value described is either identical with the classical notion of intrinsic value or is not a plausible candidate for the primary concept of axiology
Maxwell-Chern-Simons theory for curved spacetime backgrounds
We consider a modified version of four-dimensional electrodynamics, which has
a photonic Chern-Simons-like term with spacelike background vector in the
action. Light propagation in curved spacetime backgrounds is discussed using
the geometrical-optics approximation. The corresponding light path is modified,
which allows for new effects. In a Schwarzschild background, for example, there
now exist stable bounded orbits of light rays and the two polarization modes of
light rays in unbounded orbits can have different gravitational redshifts. An
Erratum with important corrections has been published, which appears as
Appendix E in this arXiv version.Comment: 28 pages with elsart, v6: published version of paper and Erratu
Combinatorial Properties of Triangle-Free Rectangle Arrangements and the Squarability Problem
We consider arrangements of axis-aligned rectangles in the plane. A geometric
arrangement specifies the coordinates of all rectangles, while a combinatorial
arrangement specifies only the respective intersection type in which each pair
of rectangles intersects. First, we investigate combinatorial contact
arrangements, i.e., arrangements of interior-disjoint rectangles, with a
triangle-free intersection graph. We show that such rectangle arrangements are
in bijection with the 4-orientations of an underlying planar multigraph and
prove that there is a corresponding geometric rectangle contact arrangement.
Moreover, we prove that every triangle-free planar graph is the contact graph
of such an arrangement. Secondly, we introduce the question whether a given
rectangle arrangement has a combinatorially equivalent square arrangement. In
addition to some necessary conditions and counterexamples, we show that
rectangle arrangements pierced by a horizontal line are squarable under certain
sufficient conditions.Comment: 15 pages, 13 figures, extended version of a paper to appear at the
International Symposium on Graph Drawing and Network Visualization (GD) 201
Generalization of Linearized Gouy-Chapman-Stern Model of Electric Double Layer for Nanostructured and Porous Electrodes: Deterministic and Stochastic Morphology
We generalize linearized Gouy-Chapman-Stern theory of electric double layer
for nanostructured and morphologically disordered electrodes. Equation for
capacitance is obtained using linear Gouy-Chapman (GC) or
Debye-ckel equation for potential near complex
electrode/electrolyte interface. The effect of surface morphology of an
electrode on electric double layer (EDL) is obtained using "multiple scattering
formalism" in surface curvature. The result for capacitance is expressed in
terms of the ratio of Gouy screening length and the local principal radii of
curvature of surface. We also include a contribution of compact layer, which is
significant in overall prediction of capacitance. Our general results are
analyzed in details for two special morphologies of electrodes, i.e.
"nanoporous membrane" and "forest of nanopillars". Variations of local shapes
and global size variations due to residual randomness in morphology are
accounted as curvature fluctuations over a reference shape element.
Particularly, the theory shows that the presence of geometrical fluctuations in
porous systems causes enhanced dependence of capacitance on mean pore sizes and
suppresses the magnitude of capacitance. Theory emphasizes a strong influence
of overall morphology and its disorder on capacitance. Finally, our predictions
are in reasonable agreement with recent experimental measurements on
supercapacitive mesoporous systems
Orientation-Constrained Rectangular Layouts
We construct partitions of rectangles into smaller rectangles from an input
consisting of a planar dual graph of the layout together with restrictions on
the orientations of edges and junctions of the layout. Such an
orientation-constrained layout, if it exists, may be constructed in polynomial
time, and all orientation-constrained layouts may be listed in polynomial time
per layout.Comment: To appear at Algorithms and Data Structures Symposium, Banff, Canada,
August 2009. 12 pages, 5 figure
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