Friction and wear behaviours of surface densified powder metallurgy Fe–2Cu–0.6C material

Surface rolling was employed to fabricate a densified layer on a powder metallurgy (PM) Fe–2Cu–0.6C piece. A densified surface layer with a depth of 335?μm and a surface hardness of 330?HV_0.1 was obtained, in which the lamellar spacing of pearlite and grain size of ferrite were refined. Friction and wear behaviours of the surface densified material were studied. Results indicated that friction coefficient of the rolled material decreased as the load increased, which was lower than that of the un-rolled material. Wear volumes were lower than that of the un-rolled material, which increased as the load increased. Wear loss was caused by flake spalling and grooves, and the wear mechanism mainly was abrasive wear. The surface densified layer with higher hardness and lower porosity can hinder the cracks initiation and propagation on the surface and under the surface, which enhance the wear resistance of the PM material.     

Stereo vision-based road estimation assisted by efficient planar patch calculation

A robust and accurate road model estimation algorithm can greatly improve the performance of many Advanced Driver Assistance Systems applications such as lane detection, obstacle detection and road marking recognition. To estimate the road model, the proposed algorithm employs a stereo vision camera system. In this paper, local planar patches are efficiently estimated in the disparity domain rather than conventionally in the Euclidean domain. Then, the estimated planar patch orientations are integrated to the fitting stage, and orientation differences are minimized along with height differences. Moreover, patch orientation differences are exploited for weighting data points. Thus, outliers become insignificant in the fitting stage, and the road model is estimated robustly and accurately without any prior knowledge of any extrinsic camera parameters. Experiments have been carried out for a free space calculation application, and the road is segmented with a true positive rate (TPR) of 88 %.     

Geometrical dependence of thermal conductivity in elliptical and rectangular nanowires

The aim of this work is to analyze the shape dependence of the effective thermal conductivity of nanowires, based on the model of phonon hydrodynamics. In particular, we consider elliptical and rectangular nanowires, and we compare their respective thermal conductivities with those of circular nanowires and of wide thin plates.     

Validation of coastal sea and lake surface temperature measurements derived from NOAA/AVHRR data

An interactive validation monitoring system is being used at the NOAA/NESDIS to validate the sea surface temperature (SST) derived from the NOAA-12 and NOAA-14 polar orbiting satellite AVHRR sensors for the NOAA CoastWatch program. In 1997, we validated the SST in coastal regions of the Gulf of Mexico, Southeast US and Northeast US and the lake surface temperatures in the Great Lakes every other month. The in situ     

Sources of Variability and Lower Values in Toughness Measurements of Weld Metals

In this paper, the sources of variability and lower values in toughness measurements of a high-strength low alloy weld metal are investigated by detailed observations of fracture surfaces and the microstructures at crack initiation. The results reveal that the variability of the notch Charpy toughness is related to the location of the cleavage initiation origins. The three factors jointly contribute to give rise to variability and lower value of toughness. That is, (1) the location that the notch is sampled at deposited weld metal or reheated weld metal, (2) the location that a large grain region is appeared on the path ahead of the notch root, (3) the distributed location of the defect or the brittle second-phase particle. When three factors were simultaneously satisfied, the lower value of the Charpy toughness is appeared. The notch is sampled at the largest grain region at deposited weld metal, and the defect or the brittle second-phase particle is close to the notch root and sampled by its high stress field, the lowest Charpy toughness is obtained.