Noise reduction of plenum windows on the façade of a high-rise residential building next to heavy road traffic

Extensive traffic noise transmission loss measurements were carried out inside selected residential units of a standalone 32-storey housing block located next to a very busy and noisy main trunk road in the present study. A total of 35 units, which were all equipped with plenum windows, was surveyed. These plenum windows are intended to help reduce noise exposure of the residents and at the same time allow for a reasonable level of natural ventilation. The results show that the traffic noise transmission losses of the unit façades installed with the plenum windows adopted in this housing block vary between 10.6 and 13.0 dBA and are only weakly dependent on elevation from the trunk road. The results also validate in-situ the prediction model established previously by the authors using laboratory and site mockup data. Generalized models for both empirical and experimental estimation of the traffic noise transmission loss across a residential flat unit façade installed with multiple plenum windows are developed. The differences between their estimations are well within engineering tolerance

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Noise reduction of enhanced acoustic balconies on a high-rise building block

Device called”enhanced acoustic balcony” is installed in a public housing development in Hong Kong. It is intended to help mitigate the impact of traffic noise on the residents. This balcony is basically an enlarged form of a plenum window allowing a more decent ventilation path. Apart from the outdoor air fenestration, there is a balcony door and window(s) on the interior balcony wall for natural ventilation of the indoor habitable area. Sound absorption material of NRC 0.7 is installed on the balcony ceiling and its sidewall facing the traffic noise and projected inclined panel is installed outside the balcony for further noise screening. On-site measurement of its noise reduction is carried out in the present study in a newly completed housing block. A 28 m long loudspeaker array is used as the sound source. The indoor noise levels are measured according to ISO standard. The results show that the difference between indoor and outdoor noise levels in the presence of this balcony form varies over a relatively narrow range between 10 to 13 dBA for an elevation angle from 25 to ~60 degrees. There is a insignificant increase of the noise level difference with elevation angle

Precision luminosity measurement in proton-proton collisions at root S=13 TeV in 2015 and 2016 at CMS

The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton-proton collisions at root S = 13 TeV in 2015 and 2016, is reported. The absolute luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3 fb(-1) in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.Peer reviewe