| 1. |
- Ballan, M., et al.
(författare)
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Nuclear physics midterm plan at Legnaro National Laboratories (LNL)
- 2023
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Ingår i: European Physical Journal Plus. - 2190-5444. ; 138:8, s. 3-26
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Tidskriftsartikel (refereegranskat)abstract
- The next years will see the completion of the radioactive ion beam facility SPES (Selective Production of Exotic Species) and the upgrade of the accelerators complex at Istituto Nazionale di Fisica Nucleare – Legnaro National Laboratories (LNL) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics, and applications. The nuclear physics community has organised a workshop to discuss the new physics opportunities that will be possible in the near future by employing state-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.
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| 2. |
- Valiente-Dobon, J. J., et al.
(författare)
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Conceptual design of the AGATA 2 pi array at LNL
- 2023
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1049
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Tidskriftsartikel (refereegranskat)abstract
- The Advanced GAmma Tracking Array (AGATA) has been installed at Laboratori Nazionali di Legnaro (LNL), Italy. In this installation, AGATA will consist, at the beginning, of 13 AGATA triple clusters (ATCs) with an angular coverage of 1n,and progressively the number of ATCs will increase up to a 2 pi angular coverage. This setup will exploit both stable and radioactive ion beams delivered by the Tandem-PIAVE-ALPI accelerator complex and the SPES facility. The new implementation of AGATA at LNL will be used in two different configurations, firstly one coupled to the PRISMA large-acceptance magnetic spectrometer and lately a second one at Zero Degrees, along the beam line. These two configurations will allow us to cover a broad physics program, using different reaction mechanisms, such as Coulomb excitation, fusion-evaporation, transfer and fission at energies close to the Coulomb barrier. These setups have been designed to be coupled with a large variety of complementary detectors such as charged particle detectors, neutron detectors, heavy-ion detectors, high-energy gamma-ray arrays, cryogenic and gasjet targets and the plunger device for lifetime measurements. We present in this paper the conceptual design, characteristics and performance figures of this implementation of AGATA at LNL.
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| 3. |
- Polettini, M., et al.
(författare)
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Decay studies in the A∼225 Po-Fr region from the DESPEC campaign at GSI in 2021
- 2022
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Ingår i: Il Nuovo Cimento. - : Società Italiana di Fisica. - 2037-4909. ; 45:5
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Tidskriftsartikel (refereegranskat)abstract
- The HISPEC-DESPEC collaboration aims at investigating the structure of exotic nuclei formed in fragmentation reactions with decay spectroscopy measurements, as part of the FAIR Phase-0 campaign at GSI. This paper reports on first results of an experiment performed in spring 2021, with a focus on beta-decaystudies in the Po-Fr nuclei in the 220 < A <230 island of octupole deformation exploiting the DESPEC setup. Ion-beta correlations and fast-timing techniques are being employed, giving an insight into this difficult-to-reach region.
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| 4. |
- Jaworski, G., et al.
(författare)
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The New Neutron Multiplicity Filter NEDA and Its First Physics Campaign with AGATA
- 2019
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 50:3, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- A new neutron multiplicity filter NEDA, after a decade of design, R&D and construction, was employed in its first physics campaign with the AGATA spectrometer. Properties and performance of the array are discussed.
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| 5. |
- Valiente-Dobon, J. J., et al.
(författare)
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NEDA-NEutron Detector Array
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 927, s. 81-86
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Tidskriftsartikel (refereegranskat)abstract
- The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.
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| 6. |
- Zanon, I., et al.
(författare)
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High-Precision Spectroscopy of 20O Benchmarking Ab Initio Calculations in Light Nuclei
- 2023
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:26
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Tidskriftsartikel (refereegranskat)abstract
- The excited states of unstable 20O were investigated via γ-ray spectroscopy following the 19O(d,p)20O reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2+2 and 3+1 states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2+2 and 3+1 states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.
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| 7. |
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| 8. |
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| 9. |
- Stacey, Simon N, et al.
(författare)
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Ancestry-shift refinement mapping of the C6orf97-ESR1 breast cancer susceptibility locus.
- 2010
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Ingår i: PLoS genetics. - : Public Library of Science. - 1553-7404. ; 6:7, s. e1001029-
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Tidskriftsartikel (refereegranskat)abstract
- We used an approach that we term ancestry-shift refinement mapping to investigate an association, originally discovered in a GWAS of a Chinese population, between rs2046210[T] and breast cancer susceptibility. The locus is on 6q25.1 in proximity to the C6orf97 and estrogen receptor alpha (ESR1) genes. We identified a panel of SNPs that are correlated with rs2046210 in Chinese, but not necessarily so in other ancestral populations, and genotyped them in breast cancer case:control samples of Asian, European, and African origin, a total of 10,176 cases and 13,286 controls. We found that rs2046210[T] does not confer substantial risk of breast cancer in Europeans and Africans (OR = 1.04, P = 0.099, and OR = 0.98, P = 0.77, respectively). Rather, in those ancestries, an association signal arises from a group of less common SNPs typified by rs9397435. The rs9397435[G] allele was found to confer risk of breast cancer in European (OR = 1.15, P = 1.2 x 10(-3)), African (OR = 1.35, P = 0.014), and Asian (OR = 1.23, P = 2.9 x 10(-4)) population samples. Combined over all ancestries, the OR was 1.19 (P = 3.9 x 10(-7)), was without significant heterogeneity between ancestries (P(het) = 0.36) and the SNP fully accounted for the association signal in each ancestry. Haplotypes bearing rs9397435[G] are well tagged by rs2046210[T] only in Asians. The rs9397435[G] allele showed associations with both estrogen receptor positive and estrogen receptor negative breast cancer. Using early-draft data from the 1,000 Genomes project, we found that the risk allele of a novel SNP (rs77275268), which is closely correlated with rs9397435, disrupts a partially methylated CpG sequence within a known CTCF binding site. These studies demonstrate that shifting the analysis among ancestral populations can provide valuable resolution in association mapping.
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| 10. |
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| 11. |
- Zanon, M., et al.
(författare)
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Microwave-assisted methacrylation of chitosan for 3D printable hydrogels in tissue engineering
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 3:1, s. 514-525
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Tidskriftsartikel (refereegranskat)abstract
- Light processable natural polymers are highly attractive for 3D printing of biomedical hydrogels with defined geometries and sizes. However, functionalization with photo-curable groups, such as methacrylate or acrylate groups, is required. Here, we investigated a microwave-assisted process for methacrylation of chitosan to replace conventional methacrylation processes that can be time consuming and tedious. The microwave-assisted methacrylation reaction was optimized by varying the synthesis parameters such as the molar ratio of chitosan to the methacrylic agent, the launch and reaction times and process temperature. The optimized process was fast and efficient and allowed tuning of the degree of substitution and thereby the final hydrogel properties. The successful methacrylation and degree of substitution were verified by 1H NMR and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The influence of the degree of methacrylation on photo-rheology, mechanical stiffness, swelling degree and gel content was evaluated. Furthermore, favourable 3D printability, enzymatic degradability, biocompatibility, cell migration and proliferation were demonstrated giving promise for further applications in tissue engineering.
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| 12. |
- Jin, S. Y., et al.
(författare)
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Spectroscopy of 98Cd by two-nucleon removal from 100In
- 2021
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Ingår i: Physical Review C: covering nuclear physics. - 2469-9985. ; 104:2
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Tidskriftsartikel (refereegranskat)abstract
- Low-lying states of Cd-98 have been populated by the two-nucleon removal reaction (In-100, Cd-98+gamma) and studied using in-beam gamma-ray spectroscopy at the Radioactive Isotope Beam Factory at RIKEN. Two new gamma transitions were identified and assigned as decays from a previously unknown state. This state is suggested to be based on a pi 1g(/9/2)(-1)2p(1/2)(-2) configuration with J(pi) = 5(-). The present observation extends the systematics of the excitation energies of the first 5(-) state in N = 50 isotones toward Sn-100. The determined energy of the 5(- )state in Cd-98 continues a smooth trend along the N = 50 isotones. The systematics are compared with shell-model calculations in different model spaces. Good agreement is achieved when considering a model space consisting of the pi(1f(5/2), 2p(3/2), 2p(1/2), 1g(9/2)) orbitals. The calculations with a smaller model space omitting the orbitals below the Z = 38 subshell could not reproduce the experimental energy difference between the ground and first 5(-) states in N = 50 isotones, because proton excitations across Z = 38 subshell yield a large amount of correlation energy that lowers the ground states.
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| 13. |
- Zanon, M., et al.
(författare)
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Airborne wind energy: Airfoil-airmass interaction
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; 19, s. 5814-5819
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Konferensbidrag (refereegranskat)abstract
- The Airborne Wind Energy paradigm proposes to generate energy by flying a tethered airfoil across the wind flow at a high velocity. While Airborne Wind Energy enables flight in higher-altitude, stronger wind layers, the extra drag generated by the tether motion imposes a significant limit to the overall system efficiency. To address this issue, two airfoils with a shared tether can reduce overall system drag. A study proposed in Zanon et al. (2013) confirms this claim by showing that, in the considered scenario, the dual-airfoil system is more advantageous than the single-airfoil one. The results computed in Zanon et al. (2013) however, do not model the interaction between the airfoils and the airmass. In this paper, the impact of the airfoil-airmass interaction on the extracted power is studied. As this phenomenon is complex to model, a blade element-momentum approach is proposed and the problem is solved by means of optimal control techniques.
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| 14. |
- Zanon, M., et al.
(författare)
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Indefinite linear MPC and approximated economic MPC for nonlinear systems
- 2014
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Ingår i: Journal of Process Control. - : Elsevier BV. - 0959-1524. ; 24:8, s. 1273-1281
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Tidskriftsartikel (refereegranskat)abstract
- The stability proof for economic model predictive control (MPC) relies on strict dissipativity, which is in general hard to check. In this contribution, we will first analyze the linear quadratic case with possibly indefinite cost. The conditions for stability will be recalled and it will be shown that every stabilizing LQR/MPC has an equivalent positive definite LQR/MPC which yields the same open loop and closed loop behavior. This analysis will then be used to formulate an approximated nonlinear economic MPC scheme, which has stability guarantees. An example will be used to illustrate the proposed technique and show its potential in terms of performance.
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| 15. |
- Zanon, M., et al.
(författare)
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Local properties of economic NMPC, dissipativity and dynamic programming
- 2015
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; 2015-February, s. 2746-2751
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Konferensbidrag (refereegranskat)abstract
- Classical model predictive control (MPC) implementations rely on a quadratic, positive definite cost function. In economic MPC on the contrary, the stage cost can be any generic function. Recent research has focused on establishing the conditions for stability of economic MPC where strict dissipativity has been shown to play an important role. In this paper, starting from the linear quadratic case and successively extending the analysis to the nonlinear case, we attempt at clarifying the relationship between strict dissipativity and the properties of the MPC optimal control problem.
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| 16. |
- Zanon, M., et al.
(författare)
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Lyapunov Function for Periodic Economic Optimizing Model Predictive Control
- 2013
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Ingår i: Conference on Decision and Control, 2013.
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Konferensbidrag (refereegranskat)abstract
- Model Predictive Control (MPC) schemes are commonly using reference-tracking cost functions, which have attractive properties in terms of stability and numerical implementation. However, many control applications have clear economic objectives that can be used directly as the NMPC cost function. Such NMPC schemes are labelled Economic NMPC. Unfortunately, Economic NMPC schemes suffer from some drawbacks. In particular, stability results for economic NMPC are still very sparse. A Lyapunov function for Economic NMPC was first proposed in [1] for problems having a steady-state optimum. The present paper develops a further generalization and clarification of these results for periodic systems.
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| 17. |
- Zanon, M., et al.
(författare)
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Model Predictive Control of Rigid-Airfoil Airborne Wind Energy Systems
- 2013
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Ingår i: U. Ahrens, M. Diehl & R. Schmehl (Eds.), Airborne Wind Energy. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 219-233
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In order to allow for a reliable and lasting operation of Airborne Wind Energy systems, several problems need to be addressed. One of the most important challenges regards the control of the tethered airfoil during power generation. Tethered flight of rigid airfoils is a fast, strongly nonlinear, unstable and constrained process, and one promising way to address the control challenge is the use of Nonlinear Model Predictive Control (NMPC) together with online parameter and state estimation based on Moving Horizon Estimation (MHE). In this paper, these techniques are introduced and their performance demonstrated in simulations of a 30 m wingspan tethered airplane with power generation in pumping mode.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Verschueren, R., et al.
(författare)
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A Sparsity Preserving Convexification Procedure for Indefinite Quadratic Programs Arising in Direct Optimal Control
- 2017
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Ingår i: SIAM Journal on Optimization. - : Society for Industrial & Applied Mathematics (SIAM). - 1052-6234 .- 1095-7189. ; 27:3, s. 2085-2109
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Tidskriftsartikel (refereegranskat)abstract
- Quadratic programs (QP) with an indefinite Hessian matrix arise naturally in some direct optimal control methods, e.g., as subproblems in a sequential quadratic programming scheme. Typically, the Hessian is approximated with a positive de finite matrix to ensure having a unique solution; such a procedure is called regularization. We present a novel regularization method tailored for QPs with optimal control structure. Our approach exhibits three main advantages. First, when the QP satisfies a second order sufficient condition for optimality, the primal solution of the original and the regularized problem are equal. In addition, the algorithm recovers the dual solution in a convenient way. Second, and more importantly, the regularized Hessian bears the same sparsity structure as the original one. This allows for the use of efficient structure-exploiting QP solvers. As a third advantage, the regularization can be performed with a computational complexity that scales linearly in the length of the control horizon. We showcase the properties of our regularization algorithm on a numerical example for nonlinear optimal control. The results are compared to other sparsity preserving regularization methods.
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| 23. |
- Zanon, Mario, 1985, et al.
(författare)
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A tracking MPC formulation that is locally equivalent to economic MPC
- 2016
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Ingår i: Journal of Process Control. - : Elsevier BV. - 0959-1524. ; 45, s. 30-42
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Tidskriftsartikel (refereegranskat)abstract
- The stability proof for economic Model Predictive Control (MPC) is in general difficult to establish. In, contrast, tracking MPC has well-established and practically applicable stability guarantees, but can yield poor closed-loop performance in terms-of the selected economic criterion. In this paper, we derive a formal procedure to design a tracking MPC scheme so as to locally approximate the behaviour of economic MPC. Given an economic stage cost, the desired tracking stage cost can therefore be computed automatically. Because tracking MPC guarantees stability of the closed-loop system, our procedure succeeds if and only if economic MPC is locally stabilising. This fact can be used to certify whether economic MPC is not stabilising. We illustrate the theoretical developments in a simulated example. (C) 2016 Elsevier Ltd. All rights reserved.
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| 24. |
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| 25. |
- Zanon, Mario, 1985, et al.
(författare)
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Periodic Optimal Control, Dissipativity and MPC
- 2017
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Ingår i: IEEE Transactions on Automatic Control. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9286 .- 1558-2523. ; 62:6, s. 2943-2949
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Tidskriftsartikel (refereegranskat)abstract
- Recent research has established the importance of (strict) dissipativity for proving stability of economic MPC in the case of an optimal steady state. Inmany cases, though, steady-state operation is not economically optimal and periodic operation of the system yields a better performance. In this technical note, we propose ways of extending the notion of (strict) dissipativity for periodic systems. We prove that optimal P-periodic operation and MPC stability directly follow, similarly to the steady-state case, which can be seen as a special case of the proposed framework. Finally, we illustrate the theoretical results with several simple examples.
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