6,002 research outputs found
Adjoint-based predictor-corrector sequential convex programming for parametric nonlinear optimization
This paper proposes an algorithmic framework for solving parametric
optimization problems which we call adjoint-based predictor-corrector
sequential convex programming. After presenting the algorithm, we prove a
contraction estimate that guarantees the tracking performance of the algorithm.
Two variants of this algorithm are investigated. The first one can be used to
solve nonlinear programming problems while the second variant is aimed to treat
online parametric nonlinear programming problems. The local convergence of
these variants is proved. An application to a large-scale benchmark problem
that originates from nonlinear model predictive control of a hydro power plant
is implemented to examine the performance of the algorithms.Comment: This manuscript consists of 25 pages and 7 figure
Analysis of directed flow from three-particle correlations
We present a new method for analysing directed flow, based on a
three-particle azimuthal correlation. It is less biased by nonflow correlations
than two-particle methods, and requires less statistics than four-particle
methods. It is illustrated on NA49 data.Comment: Contribution to Quark Matter 2002, Nantes, July 18-24, 200
Dynamics of cluster deposition on Ar surface
Using a combined quantum mechanical/classical method, we study the dynamics
of deposition of small Na clusters on Ar(001) surface. We work out basic
mechanisms by systematic variation of substrate activity, impact energy,
cluster orientations, cluster sizes, and charges. The soft Ar material is found
to serve as an extremely efficient shock absorber which provides cluster
capture in a broad range of impact energies. Reflection is only observed in
combination with destruction of the substrate. The kinetic energy of the
impinging cluster is rapidly transfered at first impact. The distribution of
the collision energy over the substrate proceeds very fast with velocity of
sound. The full thermalization of ionic and atomic energies goes at a much
slower pace with times of several ps. Charged clusters are found to have a much
stronger interface interaction and thus get in significantly closer contact
with the surface.Comment: 10 pages, 6 figures, accepted in Euro. Phys. J.
Adipocytes, aldosterone and obesity-related hypertension
Understanding the mechanisms linking obesity with hypertension is important in the current obesity epidemic as it may improve therapeutic interventions. Plasma aldosterone levels are positively correlated with body mass index and weight loss in obese patients is reported to be accompanied by decreased aldosterone levels. This suggests a relationship between adipose tissue and the production/secretion of aldosterone. Aldosterone is synthesized principally by the adrenal glands, but its production may be regulated by many factors, including factors secreted by adipocytes. In addition, studies have reported local synthesis of aldosterone in extra-adrenal tissues, including adipose tissue. Experimental studies have highlighted a role for adipocyte-secreted aldosterone in the pathogenesis of obesity-related cardiovascular complications via the mineralocorticoid receptor. This review focuses on how aldosterone secretion may be influenced by adipose tissue and the importance of these mechanisms in the context of obesity-related hypertension
On "the authentic damping mechanism" of the phonon damping model
Some general features of the phonon damping model are presented. It is
concluded that the fits performed within this model have no physical content
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