This note focuses on the control of continuous-time linear systems subject to time-domain constraints (input amplitude limitation, output overshoot) on closed-loop signals. Using recent results on ...positive polynomials, it is shown that finding a Youla-Kuc/spl breve/era polynomial parameter of fixed degree (hence, a controller of fixed order) such that time-domain constraints are satisfied amounts to solving a convex linear matrix inequality (LMI) optimization problem as soon as distinct strictly negative closed-loop poles are assigned by pole placement. Proceeding this way, time-domain constraints are handled by an appropriate choice of the closed-loop zeros.
An algorithm is presented which computes a state feedback for a standard linear system which not only stabilizes, but also dampens the closed-loop system dynamics. In other words, a feedback gain ...matrix is computed such that the eigenvalues of the closed-loop state matrix are within the region of the left half-plane where the magnitude of the real part of each eigenvalue is greater than that of the imaginary part, This may be accomplished by solving a damped algebraic Riccati equation and a degenerate Riccati equation. The solution to these equations are computed using numerically robust algorithms, Damped Riccati equations are unusual in that they may be formulated as an invariant subspace problem of a related periodic Hamiltonian system. This periodic Hamiltonian system induces two damped Riccati equations: one with a symmetric solution and another with a skew symmetric solution. These two solutions result in two different state feedbacks, both of which dampen the system dynamics, but produce different closed-loop eigenvalues, thus giving the controller designer greater freedom in choosing a desired feedback.
The article discusses a control problem when the manipulated variable is constrained to be a finite length sequence, i.e. it can modify the behaviour of the controlled system only in a limited number ...of steps and is zero afterwards. The basic criterion considered is to minimize the number of control steps or to minimize l
2
norm of the control signal. Open-loop and closed-loop formulations are presented.
We report on the measurement of the inclusive J/ Formula omitted polarization parameters in pp collisions at a center of mass energy Formula omitted TeV with the ALICE detector at the LHC. The ...analysis is based on a data sample corresponding to an integrated luminosity of 1.23 pb Formula omitted. J/ Formula omitted resonances are reconstructed in their di-muon decay channel in the rapidity interval Formula omitted and over the transverse-momentum interval Formula omitted Formula omitted. The three polarization parameters ( Formula omitted, Formula omitted, Formula omitted) are measured as a function of Formula omitted both in the helicity and Collins-Soper reference frames. The measured J/ Formula omitted polarization parameters are found to be compatible with zero within uncertainties, contrary to expectations from all available predictions. The results are compared with the measurement in pp collisions at Formula omitted TeV.
Neutral pion and Formula omitted meson invariant differential yields were measured in non-single diffractive p-Pb collisions at Formula omitted = 5.02 TeV with the ALICE experiment at the CERN LHC. ...The analysis combines results from three complementary photon measurements, utilizing the PHOS and EMCal calorimeters and the Photon Conversion Method. The invariant differential yields of Formula omitted and Formula omitted meson inclusive production are measured near mid-rapidity in a broad transverse momentum range of Formula omitted and Formula omitted, respectively. The measured Formula omitted ratio increases with Formula omitted and saturates for Formula omitted > 4 Formula omitted at Formula omitted. A deviation from Formula omitted scaling is observed for Formula omitted 2 Formula omitted. The measured Formula omitted ratio is consistent with previous measurements from proton-nucleus and pp collisions over the full Formula omitted range. The measured Formula omitted ratio at high Formula omitted also agrees within uncertainties with measurements from nucleus-nucleus collisions. The Formula omitted and Formula omitted yields in p-Pb relative to the scaled pp interpolated reference, Formula omitted, are presented for Formula omitted 20 Formula omitted and Formula omitted 20 Formula omitted, respectively. The results are compared with theoretical model calculations. The values of Formula omitted are consistent with unity for transverse momenta above 2 Formula omitted. These results support the interpretation that the suppressed yield of neutral mesons measured in Pb-Pb collisions at LHC energies is due to parton energy loss in the hot QCD medium.
Formula omitted meson measurements provide insight into strangeness production, which is one of the key observables for the hot medium formed in high-energy heavy-ion collisions. ALICE measured ...Formula omitted production through its decay in muon pairs in Pb-Pb collisions at Formula omitted TeV in the intermediate transverse momentum range Formula omitted GeV/c and in the rapidity interval Formula omitted. The Formula omitted yield was measured as a function of the transverse momentum and collision centrality. The nuclear modification factor was obtained as a function of the average number of participating nucleons. Results were compared with the ones obtained via the kaon decay channel in the same Formula omitted range at midrapidity. The values of the nuclear modification factor in the two rapidity regions are in agreement within uncertainties.
A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy sNN=5.02 TeV is presented. The semi-inclusive decay channel of beauty ...hadrons into J/ψ is considered, where the J/ψ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The bb¯ production cross section at mid-rapidity, dσbb¯/dy, and the total cross section extrapolated over full phase space, σbb¯, are obtained. This measurement is combined with results on inclusive J/ψ production to determine the prompt J/ψ cross sections. The results in p–Pb collisions are then scaled to expectations from pp collisions at the same centre-of-mass energy to derive the nuclear modification factor RpPb, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. RpPb is found to be smaller than unity at low pT for both J/ψ coming from beauty hadron decays and prompt J/ψ.
The problem of stabilization of single-input single-output discrete-time periodic systems subject to input constraint is discussed in this paper. Precisely, the initial state of the system is assumed ...to belong to a given polyhedron and the scalar input is constrained to be bounded. It is shown how this problem can be posed in terms of the polynomial description of the system. The solution can be found by using a linear programming optimization algorithm.
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