Mid-frequency prediction of transmission loss using a novel hybrid deterministic and statistical method

A novel hybrid deterministic-statistical approach named ES-FE-SEA method specially used to predict the sound Transmission loss of panels in mid-frequency is proposed in this paper. The proposed hybrid methods takes the best advantages of edged-based smoothing FEM (ES-FEM) and statistical energy analysis (SEA) to further improve the accuracy of mid-frequency transmission loss predictions. The application of ES-FEM will “soften” the well-known “overly-stiff” behavior in the standard FEM solution and reduce the inherent numerical dispersion error. While the SEA approach will deal with the physical uncertainty in the relatively higher frequency range. Two different types of subsystems will be coupled based on “reciprocity relationship” theorem. The proposed was firstly applied to a standard simple numerical example, and excellent agreement with reference results was achieved. Thus the method is then applied to a more complicated model-a 2D dash panel in a car. The proposed ES-FE-SEA is verified by various numerical examples

Ambient air pollution and adverse birth outcomes: a natural experiment study

Background Radical regulations to improve air quality, including traffic control, were implemented prior to and during the 2008 Beijing Olympic Games. Consequently, ambient concentrations of nitrogen dioxide (NO 2 ) and particular matter 10 micrometers or less (PM 10 ), were reduced in a distinct and short window of time, which presented a natural experiment for testing the relationships between maternal exposure to PM 10 and NO 2 during pregnancy and adverse birth outcomes. Methods We estimated the effect of PM 10 and NO 2 exposure during each trimester of gestation on the risk of preterm birth among live births and the birth weight among term babies. The data were based on 50,874 live births delivered between January 1, 2006 and December 31, 2010 at the Beijing Haidian Maternal and Child Health Hospital. Air monitoring data for the same period were obtained from the Beijing Municipal Environmental Monitoring Center. Results Among full-term births, maternal exposure to NO 2 in the third trimester predicted birth weight, with each 10-unit increment (per 10 ug/m 3 ) in NO 2 concentration associated with a 13.78 g (95 % confidence interval: −21.12, −6.43; p \u3c 0.0001) reduction in birth weight. This association was maintained after adjusting for other pollutants, including carbon monoxide (CO), sulfur dioxide (SO 2 ), and PM 10 . No relationship was found between the concentration of PM 10 and low birth weight among full-term births. Neither PM 10 nor NO 2 concentrations predicted the risk of premature birth. Conclusions Exposure to ambient air pollution during certain periods of pregnancy may decrease birth weight, but the effect size is small

Mantle Flow Underneath the South China Sea Revealed by Seismic Anisotropy

It Has Long Been Established that Plastic Flow in the Asthenosphere Interacts Constantly with the overlying Lithosphere and Plays a Pivotal Role in Controlling the Occurrence of Geohazards Such as Earthquakes and Volcanic Eruptions. Unfortunately, Accurately Characterizing the Direction and Lateral Extents of the Mantle Flow Field is Notoriously Difficult, Especially in Oceanic Areas Where Deployment of Ocean Bottom Seismometers (OBSs) is Expensive and Thus Rare. in This Study, by Applying Shear Wave Splitting Analyses to a Dataset Recorded by an OBS Array that We Deployed between Mid-2019 and Mid-2020 in the South China Sea (SCS), We Show that the Dominant Mantle Flow Field Has a NNW-SSE Orientation, Which Can Be Attributed to Mantle Flow Extruded from the Tibetan Plateau by the Ongoing Indian-Eurasian Collision. in Addition, the Results Suggest that E-W Oriented Flow Fields Observed in South China and the Indochina Peninsula Do Not Extend to the Central SCS