| 1. |
- Bolin, Anette, 1962-
(författare)
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Lärares samarbete med socialtjänsten
- 2011. - 1
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Ingår i: Läraryrket. - Lund : Studentlitteratur. - 9789144068497 ; , s. 209-226
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
- Zhang, Han, et al.
(författare)
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Consensus control for linear systems with optimal energy cost
- 2018
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Ingår i: Automatica. - : Elsevier. - 0005-1098 .- 1873-2836. ; 93, s. 83-91
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we design an optimal energy cost controller for linear systems asymptotic consensus given the topology of the graph. The controller depends only on relative information of the agents. Since finding the control gain for such controller is hard, we focus on finding an optimal controller among a classical family of controllers which is based on Algebraic Riccati Equation (ARE) and guarantees asymptotic consensus. Through analysis, we find that the energy cost is bounded by an interval and hence we minimize the upper bound. In order to do that, there are two classes of variables that need to be optimized: the control gain and the edge weights of the graph and are hence designed from two perspectives. A suboptimal control gain is obtained by choosing Q=0 in the ARE. Negative edge weights are allowed, and the problem is formulated as a Semi-definite Programming (SDP) problem. Having negative edge weights means that “competitions” between the agents are allowed. The motivation behind this setting is to have a better system performance. We provide a different proof compared to Thunberg and Hu (2016) from the angle of optimization and show that the lowest control energy cost is reached when the graph is complete and with equal edge weights. Furthermore, two sufficient conditions for the existence of negative optimal edge weights realization are given. In addition, we provide a distributed way of solving the SDP problem when the graph topology is regular.
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| 4. |
- Acharya, B., et al.
(författare)
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Effective-field-theory predictions of the muon-deuteron capture rate
- 2018
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 98:6
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Tidskriftsartikel (refereegranskat)abstract
- We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate. Theoretical error estimates of this low-energy process are important for a reliable interpretation of forthcoming experimental results by the MuSun Collaboration. Specifically, we estimate the three dominant sources of uncertainties that impact theoretical calculations of this rate: those resulting from uncertainties in the pool of fit data used to constrain the coupling constants in the nuclear interaction, those due to the truncation of the effective field theory, and those due to uncertainties in the axial radius of the nucleon. For the capture rate into the S01 channel, we find an uncertainty of approximately 4.6s-1 due to the truncation in the effective field theory and an uncertainty of 3.9s-1 due to the uncertainty in the axial radius of the nucleon, both of which are similar in size to the targeted experimental precision of a few percent.
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| 5. |
- Ribeiro, Yuri S., et al.
(författare)
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Low-Complexity Joint Active and Passive Beamforming Design for IRS-Assisted MIMO
- 2024
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Ingår i: IEEE Wireless Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 2162-2337 .- 2162-2345. ; 13:3, s. 607-611
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we consider an intelligent reflecting surface (IRS)-assisted multiple input multiple output (MIMO) communication and we optimize the joint active and passive beamforming by exploiting the geometrical structure of the propagation channels. Due to the inherent Kronecker product structure of the channel matrix, the global beamforming optimization problem is split into lower dimensional horizontal and vertical sub-problems. Based on this factorization property, we propose two closed-form methods for passive and active beamforming designs, at the IRS, the base station, and user equipment, respectively. The first solution is a singular value decomposition (SVD)-based algorithm independently applied on the factorized channels, while the second method resorts to a third-order rank-one tensor approximation along each domain. Simulation results show that exploiting the channel Kronecker structures yields a significant improvement in terms of computational complexity at the expense of negligible spectral efficiency (SE) loss. We also show that under imperfect channel estimation, the tensor-based solution shows better SE than the benchmark and proposed SVD-based solutions.
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