45,857 research outputs found
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Control and optimization strategies for noise transmission reduction in sonic crystal acoustic barriers
No full textAcoustic metamaterials, such as Sonic Crystals (SC), are periodic artificial structures designed to manipulate sound waves in ways that natural materials cannot. These materials consist of arranged lattices of rigid scatterers embedded in air and exhibit unique properties, such as negative refraction and Band Gaps (BG), which can be leveraged to create highly effective noise control solutions. These Band Gaps prevent transmission of certain frequency ranges depending on the angle of incidence the sound waves relative to the crystal, making them ideal for applications in noise barriers and other acoustic devices.
This research investigates the potential of these advanced materials to enhance the performance of noise reduction devices through innovative design and optimization strategies aimed at minimizing unwanted sound, thereby improving the acoustic environment in various settings. Specifically, among noise reduction devices such as barriers, absorbers, and diffusers, this thesis focuses on Sonic Crystal Noise Barriers (SCNB).
The design and optimization of these devices require a deep understanding of acoustic principles and the ability to predict how sound interacts with different materials and structures. This is achieved through the use of simulations that forecast the behavior and performance of these devices, thus saving time and resources by avoiding the need to manufacture and experimentally test multiple prototypes before arriving at the optimal solution for each specific case.
In line with this, the thesis explores the potential of Active Noise Control (ANC) systems enhanced with Reinforcement Learning (RL) techniques as a complement to improve SCNBs. By integrating reinforcement learning, the study aims to develop ANC systems that continuously learn and adapt to changing environmental conditions, providing a dynamic and adaptive approach to noise control, particularly at low frequencies, where active control is most effective, and where SCNBs tend to be less efficient.
In addition to ANC, Helmholtz Resonators (HR) are incorporated to improve these barriers. By combining numerical methods and optimization algorithms, not only is the performance of SCNBs found in the literature improved, but a deeper understanding of the physical principles governing them and their interaction with HR is also achieved. 3D printing technology, used in architectural engineering, combined with parametric modeling, greatly increases the versatility in the creation of prototypes resulting from optimizations with HRs.
This thesis also addresses the insulation capabilities of SCNBs made from cylindrical scatterers with multiple Helmholtz resonators, proposing a design that incorporates two Helmholtz resonators per scatterer. This design shows a significant increase in Insertion Loss (IL) compared to conventional barriers. Additionally,examining the interaction between the BGs of HRs and Bragg-BGs, this thesis proposes new transmission applications for multiresonant SCs beyond noise barriers. The ability to control transmission through an active metamaterial by rotating the scatterers provides an advantage over conventional passive metamaterials.
Furthermore, the thesis explores, both numerically and experimentally, wave incidence measurements to further refine noise control strategies. Prototypes designed to mitigate tonal noise, such as that produced by train braking, are experimentally tested under both normal incidence and diffuse incidence of sound waves on the SCNB.
In summary, this doctoral thesis provides a comprehensive exploration of SCNBs, from design and optimization to practical applications. It delves into the phenomenology of the interactions between these periodic materials, ANC, HRs, and 3D printing. By integrating advanced optimization techniques and reinforcement learning, the study aims to improve current noise control solutions
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Real-time-capable prediction of temperature and density profiles in a tokamak using RAPTOR and a first-principle-based transport model
No full textThe RAPTOR code is a control-oriented core plasma profile simulator with various applications in control design and verification, discharge optimization and real-time plasma simulation. To date, RAPTOR was capable of simulating the evolution of poloidal flux and electron temperature using empirical transport models, and required the user to input assumptions on the other profiles and plasma parameters. We present an extension of the code to simulate the temperature evolution of both ions and electrons, as well as the particle density transport. A proof-of-principle neural-network emulation of the quasilinear gyrokinetic QuaLiKiz transport model is coupled to RAPTOR for the calculation of first-principle-based heat and particle turbulent transport. These extended capabilities are demonstrated in a simulation of a JET discharge. The multi-channel simulation requires ∼0.2 s to simulate 1 second of a JET plasma, corresponding to ∼20 energy confinement times, while predicting experimental profiles within the limits of the transport model. The transport model requires no external inputs except for the boundary condition at the top of the H-mode pedestal. This marks the first time that simultaneous, accurate predictions of T e, T i and n e have been obtained using a first-principle-based transport code that can run in faster-than-real-time for present-day tokamaks
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
K. F. C. Rose, The date and author of the Satyricon, with an introduction by J. P. Sullivan, 1971
No full textRastier Françoise. K. F. C. Rose, The date and author of the Satyricon, with an introduction by J. P. Sullivan, 1971. In: Revue des Études Anciennes. Tome 74, 1972, n°1-4. pp. 300-303
K. F. C. Rose, The Date and Author of the Satyricon. With an Introduction by J. P. Sullivan
No full textVerdière Raoul. K. F. C. Rose, The Date and Author of the Satyricon. With an Introduction by J. P. Sullivan. In: L'antiquité classique, Tome 42, fasc. 1, 1973. pp. 279-280
K. F. C. Rose, The date and author of the Satyricon, with an introduction by J. P. Sullivan, 1971
No full textRastier Françoise. K. F. C. Rose, The date and author of the Satyricon, with an introduction by J. P. Sullivan, 1971. In: Revue des Études Anciennes. Tome 74, 1972, n°1-4. pp. 300-303
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