895 research outputs found
Approximated Computation of Belief Functions for Robust Design Optimization
This paper presents some ideas to reduce the computational cost of
evidence-based robust design optimization. Evidence Theory crystallizes both
the aleatory and epistemic uncertainties in the design parameters, providing
two quantitative measures, Belief and Plausibility, of the credibility of the
computed value of the design budgets. The paper proposes some techniques to
compute an approximation of Belief and Plausibility at a cost that is a
fraction of the one required for an accurate calculation of the two values.
Some simple test cases will show how the proposed techniques scale with the
dimension of the problem. Finally a simple example of spacecraft system design
is presented.Comment: AIAA-2012-1932 14th AIAA Non-Deterministic Approaches Conference.
23-26 April 2012 Sheraton Waikiki, Honolulu, Hawai
Expression profiling of snoRNAs in normal hematopoiesis and AML
Key Points
A subset of snoRNAs is expressed in a developmental- and lineage-specific manner during human hematopoiesis. Neither host gene expression nor alternative splicing accounted for the observed differential expression of snoRNAs in a subset of AML.</jats:p
A local-global principle for linear dependence of noncommutative polynomials
A set of polynomials in noncommuting variables is called locally linearly
dependent if their evaluations at tuples of matrices are always linearly
dependent. By a theorem of Camino, Helton, Skelton and Ye, a finite locally
linearly dependent set of polynomials is linearly dependent. In this short note
an alternative proof based on the theory of polynomial identities is given. The
method of the proof yields generalizations to directional local linear
dependence and evaluations in general algebras over fields of arbitrary
characteristic. A main feature of the proof is that it makes it possible to
deduce bounds on the size of the matrices where the (directional) local linear
dependence needs to be tested in order to establish linear dependence.Comment: 8 page
Optimal solutions to matrix-valued Nehari problems and related limit theorems
In a 1990 paper Helton and Young showed that under certain conditions the
optimal solution of the Nehari problem corresponding to a finite rank Hankel
operator with scalar entries can be efficiently approximated by certain
functions defined in terms of finite dimensional restrictions of the Hankel
operator. In this paper it is shown that these approximants appear as optimal
solutions to restricted Nehari problems. The latter problems can be solved
using relaxed commutant lifting theory. This observation is used to extent the
Helton and Young approximation result to a matrix-valued setting. As in the
Helton and Young paper the rate of convergence depends on the choice of the
initial space in the approximation scheme.Comment: 22 page
Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
We have performed thermodynamic and neutron scattering measurements on the
S=1/2 kagome lattice antiferromagnet Zn Cu_3 (OH)_6 Cl_2. The susceptibility
indicates a Curie-Weiss temperature of ~ -300 K; however, no magnetic order is
observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low
energy spin excitations with no observable gap down to 0.1 meV. The specific
heat at low-T follows a power law with exponent less than or equal to 1. These
results suggest that an unusual spin-liquid state with essentially gapless
excitations is realized in this kagome lattice system.Comment: 4 pages, 3 figures; v2: Updates to authors list and references; v3:
Updated version; v4: Published versio
Effects of Cognitive Fatigue on High Intensity Circuit Exercise: Preliminary study
Please refer to the pdf version of the abstract located adjacent to the title
High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCuVO(OH)
High-field electron spin resonance (ESR) measurements have been performed on
vesignieite BaCuVO(OH), which is considered as a nearly ideal
model substance of =1/2 kagome antiferromagnet, in the temperature region
from 1.9 to 265 K. The frequency region is from 60 to 360 GHz and the applied
pulsed magnetic field is up to 16 T. Observed g-value and linewidth show the
increase below 20 K, which suggest the development of the short range order.
Moreover, a gapless spin liquid ground state is suggested from the
frequency-field relation at 1.9 K.Comment: 5 pages, 6 figures, jpsj2 class file, to be published in J. Phys.
Soc. Jp
On the class SI of J-contractive functions intertwining solutions of linear differential equations
In the PhD thesis of the second author under the supervision of the third
author was defined the class SI of J-contractive functions, depending on a
parameter and arising as transfer functions of overdetermined conservative 2D
systems invariant in one direction. In this paper we extend and solve in the
class SI, a number of problems originally set for the class SC of functions
contractive in the open right-half plane, and unitary on the imaginary line
with respect to some preassigned signature matrix J. The problems we consider
include the Schur algorithm, the partial realization problem and the
Nevanlinna-Pick interpolation problem. The arguments rely on a correspondence
between elements in a given subclass of SI and elements in SC. Another
important tool in the arguments is a new result pertaining to the classical
tangential Schur algorithm.Comment: 46 page
High‐Frequency Sensor Data Reveal Across‐Scale Nitrate Dynamics in Response to Hydrology and Biogeochemistry in Intensively Managed Agricultural Basins
An edited version of this paper was published by AGU. Copyright 2018 American Geophysical Union.Excess nitrate in rivers draining intensively managed agricultural watersheds has caused coastal hypoxic zones, harmful algal blooms, and degraded drinking water. Hydrology and biogeochemical transformations influence nitrate concentrations by changing nitrate supply, removal, and transport. For the Midwest Unites States, where much of the land is used for corn and soybean production, a better understanding of the response of nitrate to hydrology and biogeochemistry is vital in the face of high nitrate concentrations coupled with projected increases of precipitation frequency and magnitude. In this study, we capitalized on the availability of spatially and temporally extensive sensor data in the region to evaluate how nitrate concentration (NO3−) interacts with discharge (Q) and water temperature (T) within eight watersheds in Iowa, United States, by evaluating land use characteristics and multiscale temporal behavior from 5‐year, high‐frequency, time series records. We show that power spectral density of Q, NO3−, and T, all exhibit power law behavior with slopes greater than 2, implying temporal self‐similarity for a range of scales. NO3− was strongly cross correlated with Q for all sites and correlation increased significantly with drainage area across sites. Peak NO3− increased significantly with crop coverage across watersheds. Temporal offsets in peak NO3− and peak Q, seen at all study sites, reduced the impact of extreme events. This study illustrates a relatively new approach to evaluating environmental sensor data and revealed characteristics of watersheds in which extreme discharge events have the greatest consequences
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