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Background Little is known about the exposure of young children to radiofrequency electromagnetic fields (RF-EMF) and potentially associated health effects. We assessed the relationship between residential RF-EMF exposure from mobile phone base stations, residential presence of indoor sources, personal cell phone and cordless phone use, and children's cognitive function at 5–6 years of age. Methods Cross-sectional study on children aged 5–6 years from the Amsterdam Born Children and their Development (ABCD) study, the Netherlands (n=2354). Residential RF-EMF exposure from mobile phone base stations was estimated with a 3D geospatial radio wave propagation model. Residential presence of indoor sources (cordless phone base stations and Wi-Fi) and children's cell phone and cordless phone use was reported by the mother. Speed of information processing, inhibitory control, cognitive flexibility, and visuomotor coordination was assessed using the Amsterdam Neuropsychological Tasks. Results Residential presence of RF-EMF indoor sources was associated with an improved speed of information processing. Higher residential RF-EMF exposure from mobile phone base stations and presence of indoor sources was associated with an improved inhibitory control and cognitive flexibility whereas we observed a reduced inhibitory control and cognitive flexibility with higher personal cordless phone use. Higher residential RF-EMF exposure from mobile phone base stations was associated with a reduced visuomotor coordination whereas we observed an improved visuomotor coordination with residential presence of RF-EMF indoor sources and higher personal cell phone use. Conclusions We found inconsistent associations between different sources of RF-EMF exposure and cognitive function in children aged 5–6 years. [ABSTRACT FROM AUTHOR]

For the purpose of understanding the effects of rotation on wave propagation within a tire’s treadband, the vibration of an inflated, circular cylindrical shell, rotating about a fixed axis has been considered here. The equations of motion of the rotating shell are formulated in a fixed reference frame (i.e., Eulerian co-ordinates). By assuming wave-like solutions for the free vibration case, the natural frequencies and corresponding wave-like basis functions can then be obtained. A natural frequency selection procedure is introduced that can be used to associate each of the basis functions with a single natural frequency. The basis functions are then superimposed to represent the forced response of the system when driven by a point harmonic force at a fixed location in the reference frame. By using the procedure described here, the coefficients of the basis functions can be obtained directly by solving an uncoupled ordinary differential equation. Finally, the resulting forced responses are presented in both the spatial and wave number domains, and the wave number spectrum of the rotating shell is compared with that of a stationary shell. Based on the results presented here, it is suggested that at typical rotational speeds it may be possible to use a stationary tire analysis to predict the characteristics of a rotating tire after performing a simple kinematic compensation. [Copyright &y& Elsevier]

Four models are employed to analyze wave propagation from impact on a weak viscoelastic layer. Each model is exploited on the basis of its particular strength and all four are used co-operatively in a study that overcomes the limitations of each. These models are: a numerical finite volume model serving as reference which couples motions of projectile and layer, a two-dimensional viscoelastic model with prescribed pressure on the boundary, and two versions of a three-dimensional axisymmetric elastic model; one with prescribed pressure at the boundary, and one with prescribed velocity at the boundary. This last model superimposes the responses from several external annular pressure segments of unit intensity with time-dependent weights yielding a combined response equal to the prescribed instantaneous velocity. Stress histories from all models are comparable with greatest difference near the excited boundary. [Copyright &y& Elsevier]

The crossover or the Y-pipe that connects the two banks of a V-engine to a single exhaust duct in vehicles play a significant role in the relative arrival times of the primary pressure pulses in the Y-connector, thereby affecting the tailpipe-outlet sound quality. To quantify this behavior at full as well as part-load, dynamometer experiments are conducted on an even firing General Motors 4.3L V6 engine with two different crossover pipes: one with unequal and the other with equal branch lengths. The instantaneous crank-angle resolved pressure data is acquired simultaneously both inside the exhaust duct and externally at the tailpipe outlet. The in-duct measurements employ a piezoresistive pressure transducer, while the external tailpipe-outlet measurements use a binaural acoustic head. The significant impact of the branch-length inequality is established by examining the in-duct order content and tailpipe-outlet sound quality. [Copyright &y& Elsevier]