Passivity-based control of islanded microgrids with unknown power loads

In this paper, the control problem of microgrids (MGs)operating in islanded mode is approached from a passivity-based control perspective. A control scheme is proposed that, relying only on local measurements for the power converters included in the network representation, achieves both voltage regulation and power balance in the network through the generation of grid-forming and grid-following nodes. From the mathematical perspective, the importance of the contribution lies in the feature that, exploiting a port-controlled Hamiltonian representation of the MG, the closed-loop system’s stability properties are formally proved using arguments from the theory of non-linear dynamical systems. Fundamental for this achievement is the decomposition of the system into subsystems that require a control law and another whose variables can evolve in a free way. From the practical viewpoint, the advantage of the proposed controller lies in the feature that the power demanded by the loads is satisfied without neither computing its specific value nor solving the non-linear algebraic equations given by the power flow, avoiding the computational burden associated with this task. The usefulness of the scheme is illustrated via a numerical simulation that includes practical considerations.Universidad Tecnológica de Bolíva

Desafíos de las metrópolis: Efectos ambientales y sociales. Tendencias geográficas II

El libro está conformado de estudios realizados por profesores-investigadores de la Universidad Autónoma del Estado de México, de la Universidad de Varsovia, así como de la Universidad Pedagógica Comisión de Educación Nacional de Cracovia. En esta obra se exponen algunas investigaciones sobre los cambios en los factores sociales, naturales, económicos y ambientales como principales desafios que presentan las zonas de México, Polonia y de contextos de Sudamérica, tales como Sao Paulo, Quito y Bogotá y ciudades medias y pequeñas.Universidad Autónoma del Estado de Méxic

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Global position-feedback tracking control of flexible-joint robots

International audienceWe solve the open problem of global tracking control of 2nd-degree under-actuated lossless (without friction) Lagrangian systems via position measurements only. For flexible-joint robots, we design a dynamic controller which is based on measurements of link and joint positions only. Then, approximate differentiation is used for link velocities and a simple Luenberger observer for rotor velocities. The main results constitute a significant extension of recent work on observerless output-feedback control of Lagrangian systems. Strictly speaking, we establish uniform global asymptotic stability for the closed loop system

A simple PI2D output feedback controller for the permanent magnet synchronous motor

International audienceIn this paper it is presented a PI control scheme with guaranteed stability properties for the Permanent Magnet Synchronous Motor (PMSM). The proposed controller solves the speed tracking control problem and is of the output feedback type, since it is assumed that only stator currents and the rotor position are available for measurement, i.e. it is avoided the use of (noisy) speed sensors. The algorithm is equipped with an adaptation mechanism that compensates a (constant) unknown load torque. From a theoretical perspective its more valuable characteristic lies in the fact that Uniform Global Exponential Stability (UGES) of the desired operation regime is achieved. The usefulness of the proposed scheme is evaluated in a numerical setting

Consensus control of flexible joint robots

International audienc

Search for the lepton flavor violating τ→\tau \to 3μ\mu decay in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceA search for the lepton flavor violating $\tau \to$ 3$\mu$ decay is performed using proton-proton collision events at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2017-2018, corresponding to an integrated luminosity of 97.7 fb$^{-1}$. Tau leptons produced in both heavy-flavor hadron and W boson decays are exploited in the analysis. No evidence for the decay is observed. The results of this search are combined with an earlier null result based on data collected in 2016 to obtain a total integrated luminosity of 131 fb$^{-1}$. The observed (expected) upper limits on the branching fraction $\mathcal{B}$($\tau \to$ 3$\mu$) at confidence levels of 90 and 95% are 2.9$\times$10$^{-8}$ (2.4$\times$10$^{-8}$) and 3.6$\times$10$^{-8}$ (3.0$\times$10$^{-8}$), respectively

Elliptic anisotropy measurement of the f0_0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition

International audienceDespite the f$_0$(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark ($\mathrm{q\bar{q}}$) meson, a tetraquark ($\mathrm{q\bar{q}q\bar{q}}$) exotic state, a kaon-antikaon ($\mathrm{K\bar{K}}$) molecule, or a quark-antiquark-gluon ($\mathrm{q\bar{q}g}$) hybrid. This paper reports strong evidence that the f$_0$(980) state is an ordinary $\mathrm{q\bar{q}}$ meson, inferred from the scaling of elliptic anisotropies ($v_2$) with the number of constituent quarks ($n_\mathrm{q}$), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f$_0$(980) state is reconstructed via its dominant decay channel f$_0$(980) $\to$$\pi^+\pi^-$, in proton-lead collisions recorded by the CMS experiment at the LHC, and its $v_2$ is measured as a function of transverse momentum ($p_\mathrm{T}$). It is found that the $n_q$ = 2 ($\mathrm{q\bar{q}}$ state) hypothesis is favored over $n_q$ = 4 ($\mathrm{q\bar{q}q\bar{q}}$ or $\mathrm{K\bar{K}}$ states) by 7.7, 6.3, or 3.1 standard deviations in the $p_\mathrm{T}$$\lt$ 10, 8, or 6 GeV/$c$ ranges, respectively, and over $n_\mathrm{q}$ = 3 ($\mathrm{q\bar{q}g}$ hybrid state) by 3.5 standard deviations in the $p_\mathrm{T}$$\lt$ 8 GeV/$c$ range. This result represents the first determination of the quark content of the f$_0$(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates

Extracting the speed of sound in the strongly interacting matter created in ultrarelativistic lead-lead collisions at the LHC

International audienceUltrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark-gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we extracted the speed of sound in this medium created using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb$^{-1}$. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of 0.241 $\pm$ 0.002 (stat) $\pm$ 0.016 (syst) in natural units. The effective medium temperature, estimated using the mean transverse momentum, is 219 $\pm$ 8 (syst) MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions