A MECHANICAL MODEL FOR THE PREDICTION OF THE TIRE/ROAD FRICTION
The viscoelastic deformation of tire rubber by road surface asperities was modeled by the rolling contact between a Kelvin solid and a surface motif, which is the part of surface profiles between two peaks. Stress and strain calculations showed that contact losses might occur locally, depending on the rolling speed, the viscoelastic properties of the Kelvin solid and the geometry of the motif. Mean vertical and horizontal forces were calculated, from which a coefficient of friction was derived. The model was successfully coupled with a profile analysis method to predict tire/road friction at low speed from road surface microtexture. The contribution of various texture scales to friction was emphasized. For the covering abstract see ITRD E118503.
SKID RESISTANCE OF ASPHALT PAVEMENT SURFACES RELATED TO THEIR MICROTEXTURE
Well-designed and constructed asphalt pavements can provide safe and durable surfaces with high-skid resistance. Pavement surface characteristics are related to their overall longitudinal profiles that contain various wavelength ranges. The range of wavelength, shorter than 10(-3) ~ 10(-4) [m], is often referred to as a microtexture and it is related to skid resistance of the surface. Many research works have been carried out about the pavement/tire interactions, however, very few of them have dealt with actually measured microtexture including the wavelength of 10(-5) [m]. The aim of this research is to acquire precise microtextures of pavement surfaces first as longitudinal profiles using a laser type profilometer. The measurements were done for 30 [mm] at the interval of 10 [m] (=10(-5) [m]). And also, dynamic friction coefficient was measured using Dynamic Friction Tester, which was recently employed as a standard tester by ASTM. The measured profiles were analyzed using conventional FFT and PSDs (Power Spectral Density) were obtained. Finally, the relationship between the measured skid resistances and the results of the analyses were discussed. As a conclusion, the most influential wavelength range was found to be 0.01 ~ 1 [mm] from the FFT analysis.
A preliminary account of a new tyrannosauroid theropod from the Wessex Formation (Early Cretaceous) of southern England
Abstract A new genus and species of coelurosaurian theropod dinosaur from the Wessex Formation (Early Cretaceous, Barremian) of the Isle of Wight, England, is described and named. Distinctive characters of the premaxilla, its dentition, maxilla and nasals allow it to be diagnosed. The teeth in the premaxilla are D-shaped in cross-section and the nasals are fused. The hands are elongate and slender and the hindlimbs are gracile. Lack of element fusion elsewhere in the skeleton suggests that it is a subadult. Numerous character states are shared with tyrannosaurids but the new taxon appears to be excluded from the group that comprises aublysodontine and tyrannosaurine tyrannosaurids. We conclude that the taxon is a basal tyrannosauroid and as such it is one of the earliest and (with the exception of some teeth and an isolated ilium from Portugal) the first from Europe. Implications for tyrannosauroid biogeography and evolution are discussed. The animal was part of an unusual taphonomic assemblage in which some elements were partially articulated while others were scattered or broken.