| 1. |
- Johansson, Björn, et al.
(author)
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Distributed Model Predictive Consensus
- 2006
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In: Proceedings of the 17th International Symposium on Mathematical Theory of Networks and Systems. ; , s. 2438-2444
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Conference paper (peer-reviewed)abstract
- In this paper we consider the problem of designing a distributed control strategy such that a linear combination of the states of a number of vehicles coincide at a given time. The vehicles are described by linear difference equations and are subject to convex input constraints. It is demonstrated how primal decomposition techniques and incremental subgradient methods allow us to find a solution in which each vehicle performs individual planning of its trajectory and exchanges critical information with neighbors only. We explore various communication, computation, and control structures, and demonstrate the performance of the algorithms by numerical examples.
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| 2. |
- Johansson, Björn, et al.
(author)
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On decentralized negotiation of optimal consensus
- 2008
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In: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 44:4, s. 1175-1179
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Journal article (peer-reviewed)abstract
- A consensus problem consists of finding a distributed control strategy that brings the state or output of a group of agents to a common value, a consensus point. In this paper, we propose a negotiation algorithm that computes an optimal consensus point for agents modeled as linear control systems subject to convex input constraints and linear state constraints. By primal decomposition and incremental subgradient methods, it is shown that the algorithm can be implemented such that each agent exchanges only a small amount of information per iteration with its neighbors.
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| 3. |
- Johansson, Björn, et al.
(author)
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Subgradient methods and consensus algorithms for solving convex optimization problems
- 2008
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In: Decision and Control, 2008. CDC 2008. 47th IEEE Conference on. - : IEEE. - 9781424431236 ; , s. 4185-4190
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Conference paper (peer-reviewed)abstract
- In this paper we propose a subgradient method for solving coupled optimization problems in a distributed way given restrictions on the communication topology. The iterative procedure maintains local variables at each node and relies on local subgradient updates in combination with a consensus process. The local subgradient steps are applied simultaneously as opposed to the standard sequential or cyclic procedure. We study convergence properties of the proposed scheme using results from consensus theory and approximate subgradient methods. The framework is illustrated on an optimal distributed finite-time rendezvous problem.
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| 4. |
- Aksyutina, Yu, et al.
(author)
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Lithium isotopes beyond the drip line
- 2008
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In: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 666:5, s. 430-434
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Journal article (peer-reviewed)abstract
- The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in the 14Be ground-state, evidence for a 13Li resonance at 1.47(31) MeV above the threshold with a width around 2 MeV has been found.
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| 5. |
- Aksyutina, Yuliya, 1983, et al.
(author)
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Properties of the 7He ground state from 8He neutron knockout
- 2009
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In: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 679:3, s. 191 - 196
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Journal article (peer-reviewed)abstract
- The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+) + n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s-wave component at low energies in the α+n relative energy spectrum. A possible low-lying exited state in 7He observed in neutron knockout data from 8He in a carbon target and tentatively interpreted as a Iπ=1/2− state, could not be observed in the present experiment. Possible explanations of the shape difference between the 7He resonance obtained in the two knockout reactions are discussed in terms of target-dependence or different reaction mechanisms at relativistic energies.
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| 6. |
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| 7. |
- Bexell, Ulf, et al.
(author)
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Bonding of vegetable oils to mercapto silane treated metal surfaces : Surface engineering on the nano scale
- 2006
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:2, s. 838-841
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Journal article (peer-reviewed)abstract
- In this paper the bonding of thin vegetable oil films on mercapto silane treated aluminium surfaces has been studied. The silane molecules are attached to the surface by metal-oxygen-silicon bonds. The coupling between the unsaturated bonds of the vegetable oil and the thiol functionalised surface was obtained through a photoinduced thiol-ene reaction. The surfaces were characterised by X-ray photoelectron spectroscopy (XPS). Vegetable oil contains both saturated and unsaturated carbon chains. For the reactions investigated in this study it is the unsaturated carbon chains that can react by a thiol-ene reaction and the results indicate that it is possible to attach a vegetable oil to a metal surface pre-treated with a thiol functionalised silane.
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