An efficient Kullback-Leibler optimization algorithm for probabilistic control design

This paper addresses the problem of iterative optimization of the Kullback-Leibler (KL) divergence on discrete (finite) probability spaces. Traditionally, the problem is formulated in the constrained optimization framework and is tackled by gradient like methods. Here, it is shown that performing the KL optimization in a Riemannian space equipped with the Fisher metric provides three major advantages over the standard methods: 1. The Fisher metric turns the original constrained optimization into an unconstrained optimization problem; 2. The optimization using a Fisher metric behaves asymptotically as a Newton method and shows very fast convergence near the optimum; 3. The Fisher metric is an intrinsic property of the space of probability distributions and allows a formally correct interpretation of a (natural) gradient as the steepest-descent method. Simulation results are presented

Oracle for guidance with deep neural networks in reusable launch vehicle landing

Oracles are of paramount importance for Deep Neural Networks training. In this paper, an oracle developed for landing reusable launch vehicles is created from a linearizing feedback control law that can perform a prescribed landing trajectory tracking. The oracle is then used to train a Deep Neural Network that can be used as a guidance system for landing maneuvers. Verification is performed by Monte-Carlo.info:eu-repo/semantics/publishedVersio

Energy management of refrigeration systems with thermal energy storage based on non-linear model predictive control

This work addresses the energy management of a combined system consisting of a refrigeration cycle and a thermal energy storage tank based on phase change materials. The storage tank is used as a cold-energy buffer, thus decoupling cooling demand and production, which leads to cost reduction and satisfaction of peak demand that would be infeasible for the original cycle. A layered scheduling and control strategy is proposed, where a non-linear predictive scheduler computes the references of the main powers involved (storage tank charging/discharging powers and direct cooling production), while a low-level controller ensures that the requested powers are actually achieved. A simplified model retaining the dominant dynamics is proposed as the prediction model for the scheduler. Economic, efficiency, and feasibility criteria are considered, seeking operating cost reduction while ensuring demand satisfaction. The performance of the proposed strategy for the system with energy storage is compared in simulation with that of a cycle without energy storage, where the former is shown to satisfy challenging demands while reducing the operating cost by up to 28%. The proposed approach also shows suitable robustness when significant uncertainty in the prediction model is considered

Optimal Control Applied to Distributed Solar Collector Fields

[EN] This work describes the optimal control of a parabolic trough solar plant when the solar radiation is subject to variations due to the passage of clouds. The objective of the control strategies developed is to optimize the generated power, unlike other strategies that pursue the maintenance of the outlet oil temperature of the solar field. The solar plant model developed includes the solar field with all its loops, as well as the power generation system and the storage system. It also models the passage of clouds with dfferent sizes of coverage of the solar field. Dierent control strategies are developed to maximize the power generated and at the same time to try to produce that power as long as possible and with the smallest variations.[ES] En este trabajo se describe el control de una planta solar de colectores cilíndrico parabólicos cuando la radiación solar está sometida a variaciones debidas al paso de nubes. El objetivo de las estrategias de control desarrolladas es optimizar la potencia generada, a diferencia de otras estrategias que persiguen el mantenimiento de la temperatura de salida del campo solar. El modelo desarrollado de la planta solar incluye tanto el campo solar con todos sus lazos, como el sistema de generación de potencia y el sistema de almacenamiento. Así mismo se modela el paso de las nubes con diferentes tamaños de cobertura del campo solar. Se desarrollan diferentes estrategias de control para maximizar la potencia generada y al mismo tiempo intentar producir dicha potencia el máximo de tiempo posible y con las menores variaciones.Este trabajo ha sido soportado por los proyectos DPI2013-44135-R y DPI2015-70973-R del Ministerio Español de Ciencia e Innovación.R. Rubio, F.; Navas, SJ.; Ollero, P.; Lemos, JM.; Ortega, MG. (2018). Control Óptimo Aplicado a Campos de Colectores Solares Distribuidos. Revista Iberoamericana de Automática e Informática industrial. 15(3):327-338. https://doi.org/10.4995/riai.2018.8944OJS327338153Abutayeh, M., Alazzam, A. and El-Khasawneh, B. 2014. Balancing heat transfer fluid flow in solar fields. Solar Energy, 105, 381-389. https://doi.org/10.1016/j.solener.2014.03.025Barão, M., Lemos, J. and Silva, R. 2002. Reduced complexity adaptive nonlinear control of a distributed collector solar field. Journal of Process Control, 12-1, 131-141.Camacho, E.F., Rubio, F.R. and Gutierrez, J.A. 1988. Modelling and Simulation of a Solar Power Plant with a Distributed Collectors System. Power Systems, Modelling and Control Applications. pp 11.3.1-11.3.5, Federation IBRA-BIRA, Bruselas.Camacho, E.F., Berenguel, M. and Rubio, F.R. 1997. Advanced control of solar plants. Springer-Verlag, London. https://doi.org/10.1007/978-1-4471-0981-5Camacho, E.F., Rubio, F.R., Berenguel, M. and Valenzuela, L. 2007. A survey on control schemes for distributed solar collector fields. Part I: Modeling and basic control approaches. Solar Energy, 81-10, 1240-1251.Camacho, E.F., Rubio, F.R., Berenguel, M. and Valenzuela, L. 2007. A survey on control schemes for distributed solar collector fields. Part II: Advanced control approaches. Solar Energy, 81-10, 1252-1272.Camacho, E.F., Berenguel, M., Rubio, F.R. and Martínez, D. 2012. Control of solar energy systems. Springer-Verlag, London. https://doi.org/10.1007/978-0-85729-916-1Camacho, E.F. and Gallego, A. 2013. Optimal operation in solar trough plants :A case study. Solar Energy, 95, 106-117. https://doi.org/10.1016/j.solener.2013.05.029Carmona, R., 1985. Análisis, modelado y control de un campo de colectores solares distribuidos con sistema de seguimiento en eje. Ph.D. Thesis.Cirre, C., Berenguel, M., Valenzuela, L. and Camacho, E.F. 2007. Feedback linearization control for a distributed solar collector field. Control Engineering Practice, 15-12, 1533-1544.Cirre, C., Berenguel, M., Valenzuela, L. and Klempous, R. 2009. Reference governor optimization and control of a distributed solar collector field. European Journal of Operational Research, 193, 709-717. https://doi.org/10.1016/j.ejor.2007.05.056Colmenar-Santos, A., Munuera-Perez, F., Tawfik, M. and Castro-Gil, M. 2014.A simple method for studying the effect of scattering of the performance parameters of parabolic trough collectors on the control of a solar field. Solar Energy, 99, 215-230.G https://doi.org/10.1016/j.solener.2013.11.004Gallego, A. and Camacho, E.F. 2012. Estimation of effective solar irradiation using an unscented kalman filter in a parabolic-trough field. Solar Energy,86-12, 3512-3518.García, S. 2012. Guía técnica de la energía solar termoeléctrica Fenercom, Capítulo 1.Lemos, J.M. 2006. Adaptive control of distributed collector solar fields. International journal of systems science, Vol. 37-8, 523-533. https://doi.org/10.1080/00207720600783686Lemos, J.M., Neves-Silva, R. and Igreja, J.M., 2014. Adaptive control of solar energy collector systems. Springer-Verlag, London. https://doi.org/10.1007/978-3-319-06853-4Lima, D., Normey-Rico, J. and Santos, T. 2016. Temperature control in a solar collector field using filtered dynamic matrix control. ISA Transactions, 62, 39-49. https://doi.org/10.1016/j.isatra.2015.09.016Lippke, F. 1995. Simulation of the part-load behavior of a 30 MWe SEGS plant. Report No. SAND95-1293, SNL, Albuquerque, NM, USA.Manzolini, G., Giostri, A., Saccilotto, C., Silva, P. and Macchi, E. 2012. A numerical model for off-design performance prediction of parabolic trough based solar power plants. Journal of Solar Energy Engineering, Vol.134. https://doi.org/10.1115/1.4005105Meaburn, A. and Hughes, F.M. 1993. Resonance Characteristics of a Distributed Solar Collector Fields. Solar Energy, 51, 3, 215-221. https://doi.org/10.1016/0038-092X(93)90099-AMontes, M., Abánades, A., Martínez-Val, J. and Valdés, M. 2009. Solar multiple optimization for a solar-only thermal power plant, using oil as heat transfer fluid in the parabolic trough collectors. Solar Energy, 83-12, 2165-2176. https://doi.org/10.1016/j.solener.2009.08.010Navas, S.J., Rubio, F.R., Ollero, P. and Ortega, M.G. 2016. Modeling and simulation of parabolic trough solar fields with partial radiation. XV European Control Conference, 31-36. https://doi.org/10.1109/ECC.2016.7810259Navas, S.J., Ollero, P. and Rubio, F.R. 2017. Optimum operating temperature of parabolic trough solar fields. Solar energy, 158, 295-302. https://doi.org/10.1016/j.solener.2017.09.022Price, H., Lupfert, E., Kearney, D., Zarza, E., Cohen, G., Gee, R. and Mahoney, R. 2002. Advances in parabolic trough solar power technology. Solar Energy, 124-2, 109-125.Romera, J.A. y Santos, M. 2017. ParaTrough v1.0: Librería en Modelica paraSimulación de Plantas Termosolares. Revista Iberoamericana de Automática e Informática Industrial (RIAI), Vol 14, 412-423. https://doi.org/10.1016/j.riai.2017.06.005Rubio, F.R., Camacho, E.F. and Berenguel, M. 2006. Control de campos de colectores solares. Revista Iberoamericana de Automática e Informática Industrial (RIAI), 3-4, 26-45.Shinskey, F. 1978. Energy conservation through control. Academic Press.Smith, R. 2005. Chemical process design and integration. Wiley.Stodola, A. 1945. Steam and gas turbines. Vol. 1, Peter Smith, New York

Robust Control of Maintenance-Phase Anesthesia

In biomedical systems, feedback control can be applied whenever adequate sensors, actuators, and sufficiently accurate mathematical models are available. The key issue is the capacity of the control algorithm to tackle the large levels of uncertainty, both structured and unstructured, associated with patient dynamics. In the particular case of intravenous anesthesia considered here, manipulated variables are drug infusion rates, administered by syringe pumps, and the measured signal outputs are the levels of hypnosis or depth of anesthesia (DoA) and of neuromuscular blockade (NMB). Figure 1 provides an example of a loop closed for the control of NMB

Software Engineering for Self-Adaptive Systems: A second Research Roadmap

The goal of this roadmap paper is to summarize the state of-the-art and identify research challenges when developing, deploying and managing self-adaptive software systems. Instead of dealing with a wide range of topics associated with the field, we focus on four essential topics of self-adaptation: design space for adaptive solutions, processes, from centralized to decentralized control, and practical run-time verification and validation. For each topic, we present an overview, suggest future directions, and focus on selected challenges. This paper complements and extends a previous roadmap on software engineering for self-adaptive systems published in 2009 covering a different set of topics, and reflecting in part on the previous paper. This roadmap is one of the many results of the Dagstuhl Seminar 10431 on Software Engineering for Self-Adaptive Systems, which took place in October 2010

Thrombocytopenia and platelet transfusions in ICU patients: an international inception cohort study (PLOT-ICU)

Purpose Thrombocytopenia (platelet count < 150 × 109/L) is common in intensive care unit (ICU) patients and is likely associated with worse outcomes. In this study we present international contemporary data on thrombocytopenia in ICU patients. Methods We conducted a prospective cohort study in adult ICU patients in 52 ICUs across 10 countries. We assessed frequencies of thrombocytopenia, use of platelet transfusions and clinical outcomes including mortality. We evaluated pre-selected potential risk factors for the development of thrombocytopenia during ICU stay and associations between thrombocytopenia at ICU admission and 90-day mortality using pre-specified logistic regression analyses. Results We analysed 1166 ICU patients; the median age was 63 years and 39.5% were female. Overall, 43.2% (95% confidence interval (CI) 40.4–46.1) had thrombocytopenia; 23.4% (20–26) had thrombocytopenia at ICU admission, and 19.8% (17.6–22.2) developed thrombocytopenia during their ICU stay. Non-AIDS-, non-cancer-related immune deficiency, liver failure, male sex, septic shock, and bleeding at ICU admission were associated with the development of thrombocytopenia during ICU stay. Among patients with thrombocytopenia, 22.6% received platelet transfusion(s), and 64.3% of in-ICU transfusions were prophylactic. Patients with thrombocytopenia had higher occurrences of bleeding and death, fewer days alive without the use of life-support, and fewer days alive and out of hospital. Thrombocytopenia at ICU admission was associated with 90-day mortality (adjusted odds ratio 1.7; 95% CI 1.19–2.42). Conclusion Thrombocytopenia occurred in 43% of critically ill patients and was associated with worse outcomes including increased mortality. Platelet transfusions were given to 23% of patients with thrombocytopenia and most were prophylactic.publishedVersio

Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV