Design and instrumentation of the SHARCS scaled rotor with three independent control systems

Design and instrumentation of the SHARCS (Smart Hybrid Active Rotor Control System) scaled rotor is presented in the paper. The goal of the project is to demonstrate the simultaneous reduction of vibration and noise on helicopters via multiple independent feedback control systems. Three actively controlled systems are implemented on a single blade: the Active Pitch Link (APL), the Actively Controlled Flap (ACF) and the Actively Controlled Tip (ACT), combining both flow control (ACF and ACT) and structural control (APL systems) approaches in a hybrid manner. First, a review of the hybrid control concept is given, followed by the description of the design requirements for each individual control system as well as for the rotor as a whole. Following this, the active control systems' design and prototypes are presented, along with the design of the composite blade structure housing them. The incorporation of three control systems called for original and unorthodox design solutions, from which the most prominent ones concern: design and prototype of the first ever smart spring concept based Active Pitch Link, the use of a counterweight based concept to reduce the extreme hinge moments acting on the Actively Controlled Tip and the design of a special removable structure called the Skeleton, housing the ACF and ACT systems and allowing easy access and maintenance of the actively controlled subsystems. Finally, the instrumentation of the rotor is presented in detail, concluding that due to the capacity of the applied slip ring unit, only separate measurements of the blade strains and the control system can be facilitated. Copyrigh

Whirl tower demonstrations of the SHARCS hybrid control concept

Elements of the SHARCS (Smart Hybrid Active Rotor Control System) Hybrid Control concept are demonstrated via two sets of whirl tower tests. Hybrid Control stands for combining a flow control (such as an Actively Controlled Flap or Active Twist Rotor) and of a structural (or stiffness) control device on a helicopter blade. A Hybrid Control system promises to reduce vibration and noise on helicopters simultaneously as well as to improve the efficiency of the flow control device. For the structural control system, a unique and entirely original Active Pitch Link has been developed at Carleton University, which is capable of dynamically controlling the torsional stiffness of a blade. Design, prototyping, static and whirl tower testing of this device is presented in the paper. A second set of whirl tower tests of an Active Twist Rotor equipped with a range of springs instead of the conventional pitch link, demonstrates that the Active Pitch Link shall indeed be capable of lowering the torsional stiffness of the blade. For these tests, the modal parameters of the blade were evaluated via a novel "Output-Only" method, which represents the first application of such methodology for rotary-wing applications.Copyrigh

Measurement of the branching fraction and CPCP asymmetry in B+→J/ψρ+B^{+}\rightarrow J/\psi \rho^{+} decays

International audienceThe branching fraction and direct $C\!P$ asymmetry of the decay ${{{B} ^+}} \!\rightarrow {{J /\psi }} {{\rho } ^+}$ are measured using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to a total integrated luminosity of 3 $\,\text{ fb }^{-1}$ . The following results are obtained: $\begin{aligned} \mathcal {B}({{B} ^+} \!\rightarrow {{J /\psi }} {{\rho } ^+} )&= (3.81^{+0.25-0.24} \pm 0.35) \times 10^{-5},\\ \mathcal {A}^{{C\!P}} ({{B} ^+} \!\rightarrow {{J /\psi }} {{\rho } ^+} )&= -0.045^{+0.056-0.057} \pm 0.008, \end{aligned}$ where the first uncertainties are statistical and the second systematic. Both measurements are the most precise to date

Amplitude analysis of the B(s)0→K∗0K‾∗0B^0_{(s)} \to K^{*0} \overline{K}^{*0} decays and measurement of the branching fraction of the B0→K∗0K‾∗0B^0 \to K^{*0} \overline{K}^{*0} decay

International audienceThe ${B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ and ${B}_s^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decays are studied using proton-proton collision data corresponding to an integrated luminosity of 3 fb$^{−1}$. An untagged and timeintegrated amplitude analysis of B_{( s}_{)}^{0}  → (K$^{+}$π$^{−}$)(K$^{−}$π$^{+}$) decays in two-body invariant mass regions of 150 MeV/c$^{2}$ around the K$^{∗0}$ mass is performed. A stronger longitudinal polarisation fraction in the ${B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decay, f$_{L}$ = 0.724 ± 0.051 (stat) ± 0.016 (syst), is observed as compared to f$_{L}$ = 0.240 ± 0.031 (stat) ± 0.025 (syst) in the ${B}_s^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decay. The ratio of branching fractions of the two decays is measured and used to determine $\mathrm{\mathcal{B}}\left({B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}\right)=\left(8.0\pm 0.9\left(\mathrm{stat}\right)\pm 0.4\left(\mathrm{syst}\right)\right)\times {10}^{-7}$

Measurement of CPCP-violating and mixing-induced observables in Bs0→ϕγB_s^0 \to \phi\gamma decays

International audienceA time-dependent analysis of the Bs0→ϕγ decay rate is performed to determine the CP -violating observables Sϕγ and Cϕγ and the mixing-induced observable AϕγΔ. The measurement is based on a sample of pp collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3  fb-1 at center-of-mass energies of 7 and 8 TeV. The measured values are Sϕγ=0.43±0.30±0.11, Cϕγ=0.11±0.29±0.11, and AϕγΔ=-0.67-0.41+0.37±0.17, where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables S and C in radiative Bs0 decays. The results are consistent with the standard model predictions

Model-Independent Observation of Exotic Contributions to B0→J/ψK+π−B^0\to J/\psi K^+\pi^- Decays

International audienceAn angular analysis of B0→J/ψK+π- decays is performed, using proton-proton collision data corresponding to an integrated luminosity of 3  fb-1 collected with the LHCb detector. The m(K+π-) spectrum is divided into fine bins. In each m(K+π-) bin, the hypothesis that the three-dimensional angular distribution can be described by structures induced only by K* resonances is examined, making minimal assumptions about the K+π- system. The data reject the K*-only hypothesis with a large significance, implying the observation of exotic contributions in a model-independent fashion. Inspection of the m(J/ψπ-) vs m(K+π-) plane suggests structures near m(J/ψπ-)=4200 and 4600 MeV

Study of Υ\Upsilon production in ppPb collisions at sNN=8.16\sqrt{s_{NN}}=8.16 TeV

International audienceThe production of ϒ(nS) mesons (n = 1, 2, 3) in pPb and Pbp collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb$^{−1}$. The ϒ(nS) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the ϒ(1S) and ϒ(2S) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum p$_{T}$ and rapidity in the nucleon-nucleon centre-of-mass frame y$^{*}$ of the ϒ(nS) states, in the kinematic range p$_{T}$ < 25 GeV/c and 1.5 < y$^{*}$ < 4.0 (−5.0 < y$^{*}$ < −2.5) for pPb (Pbp) collisions. In addition, production cross-sections for ϒ(3S) are measured integrated over phase space and the production ratios between all three ϒ(nS) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models

First Measurement of Charm Production in its Fixed-Target Configuration at the LHC

International audienceThe first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of J/ψ and D0 mesons is studied with beams of protons of different energies colliding with gaseous targets of helium and argon with nucleon-nucleon center-of-mass energies of sNN=86.6 and 110.4 GeV, respectively. The J/ψ and D0 production cross sections in pHe collisions in the rapidity range [2, 4.6] are found to be σJ/ψ=652±33(stat)±42(syst)   nb/nucleon and σD0=80.8±2.4(stat)±6.3(syst)  μb/nucleon, where the first uncertainty is statistical and the second is systematic. No evidence for a substantial intrinsic charm content of the nucleon is observed in the large Bjorken-x region