SEA analysis in the cabin of a regional turboprop with metamaterial lining panels

The main goal of this paper is to evaluate the comfort, and hence the interior sound pressure levels, in the cabin of a regional turboprop with metamaterial lining panels under Turbulent Boundary Layer flow over the fuselage during cruise flight conditions. In the preliminary work phase, the design of metamaterial and a numerical analysis at component level were performed. Then, the CAD model of the fuselage was created representing the typical features and dimensions of an airplane for regional flights and a Statistical Energy Analysis (SEA) model was built by using Va One software. An investigation on the influence of designed metamaterial on the soundproofing of the cabin was presented. Results reveal a reduction in Sound Pressure Level (SPL) of almost 5 dB with respect to classical materials, in overall the frequency range and for all the cavities analyzed, in the configuration with metamaterial applied as core of the sandwich lining panels

Growing Things Rare, Foreign, and Tender : The Early Nineteenth-Century Greenhouse at Gore Place, Waltham Massachusetts

Excavations and ground penetrating radar at Gore Place in Waltham, Massachusetts, uncovered part of an early 19th-century greenhouse (ca. 1806 to the early 1840s) constructed by Christopher and Rebecca Gore. Documentary, archaeological, and geophysical data suggest that the greenhouse was a formal space intended to display exotic plants and that it was built in the relatively new lean-to style, with a tall back wall and a short front wall. The artifact assemblage included tools and small finds related to the greenhouse operation, as well as the remains of at least 149 planting pots. The greenhouse was constructed during a period of intense interest in agricultural experimentation by members of the Massachusetts commercial and political elite, including Gore. Scholars have argued that these men used the positive associations of agriculture to offset some of the contemporary negative connotations of commerce. This article examines the greenhouse in the light of this scientific agricultural movement but also argues that the greenhouse was an extension of the social space of the house and posits that Rebecca Gore may have played a significant role in managing it

Effective conditions for the reflection of an acoustic wave by low-porosity perforated plates

International audienceThis paper describes an investigation of the acoustic properties of a low-porosity perforated plate in a compressible ideal inviscid fluid in the absence of mean flow. The study shows in particular how the reflection and transmission coefficients of an acoustic plane wave produced by such a device can be expressed in terms of the Rayleigh conductivity of an isolated perforation by extending the approach introduced for the case of thick plates by Leppington and Levine, \textit{Reflexion and transmission at a plane screen with periodically arranged circular or elliptical apertures}, J. Fluid Mech., 1973, p.109-127. Lower and upper bounds for the Rayleigh conductivity of a perforation in a thick plate are usually derived from intuitive approximations and by reasoning based on physical observation. The paper addresses a mathematical justification of these approaches, yielding accurate bounds for various geometries, untilted or tilted, with a conical shape or an elliptical section. Accurate estimates of the Rayleigh conductivity for a single perforation have a direct impact on the precision of models used for predicting the acoustic behavior of a perforated plate mainly on the basis of its reflection and transmission coefficients. It is shown in this paper how asymptotic expansions can be used to derive first and second-order accurate, albeit approximate expressions of these coefficients, as well as of the effective compliance of the perforated plate

Effects of External Vibration Stimulation on Internal Rotation Range of Motion and Hamstring Strength

Introduction Whole body and localized vibration therapy have gained increased use in the fitness community, clinical setting, and research Efficacy as a modality option is yet to be determined Objective Evaluate the effects of localized vibration treatment (LVT) to the sacral region on shoulder internal rotation (IR) range of motion (ROM) and isometric hamstring strength Participants 50 Concordia University DPT Students 28 females 22 males Age: 22-33 (Avg. 24) Methods Baseline dominant extremity shoulder IR ROM measured in supine with manual goniometry Baseline hamstring strength measurements in prone using MicroFETTM (hand held dynamometer), taken post 1 practice test Therapeutic intervention: application of LVT using the Hypervolt PlusR tool to 5 predetermined landmarks on sacral region for 40 seconds total Post-therapeutic intervention measurements Prone hamstring strength using MicroFETTM Supine shoulder IR ROM with manual goniometry Results Statistical significance (p \u3c 0.05) was demonstrated for increased shoulder IR (mean difference 3.5 degrees) Hamstring strength did not rise to statistical significance (p=0.09) Conclusion Vibration stimulation to neural dense area such as the sacral region can improve shoulder internal rotation range of motion. Clinical Relevance Potential acute gains in ROM and strength to allow for greater effectiveness in subsequent PT interventions In sport training, LVT could be used as a quick and effective tool for increased athletic performance Future Research Procedural modifications may improve outcomes Pelvis stabilization methods may demonstrate clinically significant improvements in hamstring strength Incremental testing post LVT delivery to assess duration of effect

Search for light massive gauge bosons as an explanation of the (g−2)μ(g-2)_\mu anomaly at MAMI

A massive, but light abelian U(1) gauge boson is a well motivated possible signature of physics beyond the Standard Model of particle physics. In this paper, the search for the signal of such a U(1) gauge boson in electron-positron pair-production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron (MAMI) is described. Exclusion limits in the mass range of 40 MeV up to 300 MeV with a sensitivity in the mixing parameter of down to $\epsilon^2 = 8\times 10^{-7}$ are presented. A large fraction of the parameter space has been excluded where the discrepancy of the measured anomalous magnetic moment of the muon with theory might be explained by an additional U(1) gauge boson.Comment: 4 pages, 3 figure

Acoustic radiation by vortex induced flexible wall vibration

Sound radiation due to unsteady interaction between an inviscid vortex (which models a turbulent eddy) and a finite length flexible boundary in a two-dimensional space is studied using potential theory and the matched asymptotic expansion technique. The Mach number of the vortex propagation is kept below 0.15. Results suggest that the monopole field created by the volumetric flow induced by the vibrating flexible boundary dominates the overall acoustic power radiation. The longitudinal dipole directly due to the transverse vortex acceleration is only important when the vortex is moving over the flexible boundary. The longitudinal dipole resulting from the boundary vibration gains slightly in importance in the strong vortex case, but the corresponding transverse dipole remains negligible for the cases considered in the present study. The two longitudinal dipoles give rise to biased radiation directivities on both sides of the flexible boundary. © 2005 Acoustical Society of America.published_or_final_versio

Search for lepton-flavour-violating decays of Higgs-like bosons.

A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2