22 research outputs found
Parallel gradient projection successive overrelaxation for symmetric linear complementarity problems and linear programs
A shooting algorithm for problems with singular arcs
In this article we propose a shooting algorithm for a class of optimal
control problems for which all control variables appear linearly. The shooting
system has, in the general case, more equations than unknowns and the
Gauss-Newton method is used to compute a zero of the shooting function. This
shooting algorithm is locally quadratically convergent if the derivative of the
shooting function is one-to-one at the solution. The main result of this paper
is to show that the latter holds whenever a sufficient condition for weak
optimality is satisfied. We note that this condition is very close to a second
order necessary condition. For the case when the shooting system can be reduced
to one having the same number of unknowns and equations (square system) we
prove that the mentioned sufficient condition guarantees the stability of the
optimal solution under small perturbations and the invertibility of the
Jacobian matrix of the shooting function associated to the perturbed problem.
We present numerical tests that validate our method.Comment: No. RR-7763 (2011); Journal of Optimization, Theory and Applications,
published as 'Online first', January 201
Some aspects of modelling the high-latitude ionospheric convection from Cluster/Edi data
Modeling Synergy Effects Considering Both Positive and Negative Factors Between Participants
ZurĂŒckfĂŒhrung einer Klasse von Minimum-Problemen der Steuertheorie auf Minimax-Aufgaben
Different space weather effects in anomalies of the high and low orbital satellites
Preliminary results of the EU INTAS Project 00810, which aims to improve the methods of safeguarding satellites in the Earth's
magnetosphere from the negative effects of the space environment, are presented. Anomaly data from the ââKosmosââ series satellites
in the period 1971â1999 are combined in one database, together with similar information on other spacecraft. This database contains,
beyond the anomaly information, various characteristics of the space weather: geomagnetic activity indices (Ap, AE and Dst),
fluxes and fluences of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary
and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried
out for the total number of anomalies (about 6000 events), and separately for high (~5000 events) and low (about 800 events) altitude
orbit satellites. No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies,
averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and
low (<1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the
orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found
to be different for various orbits that should be taken into account under developing of the anomaly frequency models.
© 2004 COSPAR. Published by Elsevier Ltd. All rights reserved