177,413 research outputs found
Drinfeld twists of the open XXZ chain with non-diagonal boundary terms
The Drinfeld twists or factorizing F-matrices for the open XXZ spin chain
with non-diagonal boundary terms are constructed. It is shown that in the
F-basis the two sets of pseudo-particle creation operators simultaneously take
completely symmetric and polarization free form. The explicit and completely
symmetric expressions of the two sets of Bethe states of the model are
obtained.Comment: Latex file, 25 page
Bequests and heterogeneity in retirement wealth
Households hold vastly heterogeneous amounts of wealth when they reach retirement, and differences in lifetime earnings explain only part of this variation. This paper studies the role of intergenerational transmission of ability, voluntary bequest motives, and the recipiency of accidental and intended bequests (both in terms of timing and size) in generating wealth dispersion at retirement, in the context of a rich quantitative model. Modeling voluntary bequests, and realistically calibrating them, not only generates more wealth dispersion at retirement and reduces the correlation between retirement wealth and lifetime income, but also generates a skewed bequest distribution that is close to the one in the observed data
New Coherence and RIP Analysis for Weak Orthogonal Matching Pursuit
In this paper we define a new coherence index, named the global 2-coherence,
of a given dictionary and study its relationship with the traditional mutual
coherence and the restricted isometry constant. By exploring this relationship,
we obtain more general results on sparse signal reconstruction using greedy
algorithms in the compressive sensing (CS) framework. In particular, we obtain
an improved bound over the best known results on the restricted isometry
constant for successful recovery of sparse signals using orthogonal matching
pursuit (OMP).Comment: arXiv admin note: substantial text overlap with arXiv:1307.194
Vector lattices with a Hausdorff uo-Lebesgue topology
We investigate the construction of a Hausdorff uo-Lebesgue topology on a
vector lattice from a Hausdorff (o)-Lebesgue topology on an order dense ideal,
and what the properties of the topologies thus obtained are. When the vector
lattice has an order dense ideal with a separating order continuous dual, it is
always possible to supply it with such a topology in this fashion, and the
restriction of this topology to a regular sublattice is then also a Hausdorff
uo-Lebesgue topology. A regular vector sublattice of
for a semi-finite measure falls into this
category, and the convergence of nets in its Hausdorff uo-Lebesgue topology is
then the convergence in measure on subsets of finite measure. When a vector
lattice not only has an order dense ideal with a separating order continuous
dual, but also has the countable sup property, we show that every net in a
regular vector sublattice that converges in its Hausdorff uo-Lebesgue topology
always contains a sequence that is uo-convergent to the same limit. This
enables us to give satisfactory answers to various topological questions about
uo-convergence in this context.Comment: 37 pages. Minor changes; a few references added. Final version, to
appear in J. Math. Anal. App
Free-form 2.5D thermoplastic circuits using one-time stretchable interconnections
A technology is presented for the production of soft and rigid circuits with an arbitrary 2.5D fixed shape. The base of this technology is our proprietary technology for elastic circuits with a random shape, in which the elastic thermoset (mostly PDMS) polymer is now replaced by soft or rigid thermoplastic variants. An additional thermoforming step is required to transform the circuit from its initial flat to its final fixed 2.5D shape, but for rigid fixed shape circuits only one-time stretchability of the extensible interconnects is required, relieving the reliability requirements
Self-desiccation and self-desiccation shrinkage of silica fume-cement pastes
Self-desiccation is one common phenomenon of high-performance cementitious materials, which are
characterized by low water/binder (w/b) ratio and high mineral admixture incorporation. As a
consequence, large magnitude of self-desiccation shrinkage, a key factor which influences the
cracking behavior of concrete, develops rapidly in the cement matrix due to the internal relative
humidity (RH) decrease and capillary pressure induced by self-desiccation.
The objective of this study is to evaluate the behavior of self-desiccation and self-desiccation
shrinkage in silica fume (SF) blended cement pasts with low w/b ratio of 0.25. The self-desiccation
process was revealed by the measurement of internal RH of the sealed cement pastes with
conventional method of hygrometer. The shrinkage of the sealed cement pastes was measured by the
corrugated tube method, permitting measurements to start at early age.
Experimental results revealed that SF blending leads to a higher internal RH, indicating slower
self-desiccation process, compared with pure cement paste. Consequently, less self-desiccation
shrinkage was observed in SF blended cement pastes than that in pure cement paste
Explicit memory schemes for evolutionary algorithms in dynamic environments
Copyright @ 2007 Springer-VerlagProblem optimization in dynamic environments has atrracted a growing interest from the evolutionary computation community in reccent years due to its importance in real world optimization problems. Several approaches have been developed to enhance the performance of evolutionary algorithms for dynamic optimization problems, of which the memory scheme is a major one. This chapter investigates the application of explicit memory schemes for evolutionary algorithms in dynamic environments. Two kinds of explicit memory schemes: direct memory and associative memory, are studied within two classes of evolutionary algorithms: genetic algorithms and univariate marginal distribution algorithms for dynamic optimization problems. Based on a series of systematically constructed dynamic test environments, experiments are carried out to investigate these explicit memory schemes and the performance of direct and associative memory schemes are campared and analysed. The experimental results show the efficiency of the memory schemes for evolutionary algorithms in dynamic environments, especially when the environment changes cyclically. The experimental results also indicate that the effect of the memory schemes depends not only on the dynamic problems and dynamic environments but also on the evolutionary algorithm used
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