7,165 research outputs found
DEVELOPMENT OF THE UTILIZATION OF PASTORAL LAND IN THE EU 25 AFTER 2003
Farming systems based on products of roughage feeders are a vital part of the EU agricultural production. Up to the CAP reform in 2003 the EU promoted these systems via a wide variety of measures. This paper highlights the different impacts European, national and regional support measures have on the utilization of pastoral resources across the EU-25. Based on an expert survey and a literature review the paper summarizes the expected developments of pastoral farming systems across the EU.Pastoral Systems, EU, 2003 CAP Reform, Enlargement, Land Economics/Use,
Confidence regions for the multinomial parameter with small sample size
Consider the observation of n iid realizations of an experiment with d>1
possible outcomes, which corresponds to a single observation of a multinomial
distribution M(n,p) where p is an unknown discrete distribution on {1,...,d}.
In many applications, the construction of a confidence region for p when n is
small is crucial. This concrete challenging problem has a long history. It is
well known that the confidence regions built from asymptotic statistics do not
have good coverage when n is small. On the other hand, most available methods
providing non-asymptotic regions with controlled coverage are limited to the
binomial case d=2. In the present work, we propose a new method valid for any
d>1. This method provides confidence regions with controlled coverage and small
volume, and consists of the inversion of the "covering collection"' associated
with level-sets of the likelihood. The behavior when d/n tends to infinity
remains an interesting open problem beyond the scope of this work.Comment: Accepted for publication in Journal of the American Statistical
Association (JASA
Work Roll Cooling System Design Optimisation in Presence of Uncertainty
Organised by: Cranfield UniversityThe paper presents a framework to optimise the design of work roll based on the cooling performance. The
framework develops Meta models from a set of Finite Element Analysis (FEA) of the roll cooling. A design of
experiment technique is used to identify the FEA runs. The research also identifies sources of uncertainties
in the design process. A robust evolutionary multi-objective algorithm is applied to the design optimisation I
order to identify a set of good solutions in the presence of uncertainties both in the decision and objective
spaces.Mori Seiki â The Machine Tool Compan
Entanglement spectrum and boundary theories with projected entangled-pair states
In many physical scenarios, close relations between the bulk properties of
quantum systems and theories associated to their boundaries have been observed.
In this work, we provide an exact duality mapping between the bulk of a quantum
spin system and its boundary using Projected Entangled Pair States (PEPS). This
duality associates to every region a Hamiltonian on its boundary, in such a way
that the entanglement spectrum of the bulk corresponds to the excitation
spectrum of the boundary Hamiltonian. We study various specific models, like a
deformed AKLT [1], an Ising-type [2], and Kitaev's toric code [3], both in
finite ladders and infinite square lattices. In the latter case, some of those
models display quantum phase transitions. We find that a gapped bulk phase with
local order corresponds to a boundary Hamiltonian with local interactions,
whereas critical behavior in the bulk is reflected on a diverging interaction
length of the boundary Hamiltonian. Furthermore, topologically ordered states
yield non-local Hamiltonians. As our duality also associates a boundary
operator to any operator in the bulk, it in fact provides a full holographic
framework for the study of quantum many-body systems via their boundary.Comment: 13 pages, 14 figure
Bond-order modulated staggered flux phase for the model on the square lattice
Motivated by the observation of inhomogeneous patterns in some high-T
cuprate compounds, several variational Gutzwiller-projected wave-functions with
built-in charge and bond order parameters are proposed for the extended
model on the square lattice at low doping. First, following a recent
Gutzwiller-projected mean-field approach by one of us (Phys. Rev. B. {\bf 72},
060508(R) (2005)), we investigate, as a function of doping and Coulomb
repulsion, the stability of the staggered flux phase with respect to small
spontaneous modulations of squared unit cells ranging from to
. It is found that a bond-order (BO)
modulation appears spontaneously on top of the staggered flux pattern for hole
doping around 1/8. A related wave-function is then constructed and optimized
accurately and its properties studied extensively using an approximation-free
variational Monte Carlo scheme. Finally, the competition of the BO-modulated
staggered flux wave-function w.r.t. the d-wave RVB wave-function or the
commensurate flux state is investigated. It is found that a short range Coulomb
repulsion penalizes the d-wave superconductor and that a moderate Coulomb
repulsion brings them very close in energy. Our results are discussed in
connection to the STM observations in the under-doped regime of some cuprates.Comment: 10 pages, 9 figure
- âŠ