Abstract This work investigates the causes of wear occurring at engine valve tip end after 400 hours operation. Fatigue was observed on product development stage engine, which is going to be used in an automotive vehicle. Valves were assembled a gasoline/CNG fuel-based four-cylinder IC engine. In this prominent during high-speed testing conditions as compared other types tests. The chemical com...

Active and passive methods for control of hypersonic boundary layers have been experimentally examined in NASA Langley Research Center wind tunnels on a Hyper-X model. Several configurations for forcing transition using passive discrete roughness elements and active mass addition, or blowing, methods were compared in two hypersonic facilities, the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air ...

the growing demand for enhanced esthetic appearance has led to great developments in bleaching products. the exposure of hard tissues of the tooth to bleaching agents can affect the roughness of the enamel surface. the freshly bleached enamel surface exposed to various surface treatments such as fluoride and other remineralizing agents have been assessed in this study. the aim of this experimen...

We review recent theoretical progress on the dynamics of brittle crack fronts and its relationship to the roughness of fracture surfaces. We discuss the possibility that the intermediate scale roughness of cracks, which is characterized by a roughness exponent approximately equal to 0.5, could be caused by the generation, during local instabilities by depinning, of diffusively broadened corruga...

Robin Faivre 1,2,*, Jérôme Colin 1 and Massimo Menenti 2,3 1 ICube Laboratory, UMR 7357 CNRS-University of Strasbourg, F-67412 Illkirch Cedex, France; [email protected] 2 Department of Geoscience and Remote Sensing (GRS), Delft University of Technology, 2628 CN Delft, The Netherlands; [email protected] 3 State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital...

The authors use a coupled atmosphere-ocean-wave model (SWAN) to simulate winds in a particular region on the continental shelf in the Mediterranean Sea. After showing that the model does a good job in reproducing the observed wind and wave patters, the authors use different parameterizations for the atmospheric bottom roughness length: in one case it depends on wind intensity ("uncoupled" simul...

introduction: bleaching process can affect surface roughness of enamel, which is a vital factor in esthetic and resistance of tooth. the aim of this study was to compare surface roughness of enamel in teeth bleached using diode and neodymium-doped yttrium aluminium garnet (nd: yag) lasers with those bleached using conventional method. methods: in this study, 75 anterior human teeth from upper a...

The surface roughness of two contacting surfaces significantly influences the tribological performance mechanical elements. Their impression is more pronounced under mixed elasto-hydrodynamic lubrication condition. cam and flat follower mechanism a typical sample in which adverse conditions, including direct boundary interactions occurs. In this study, effects on friction force coefficient are ...

different construction materials with different roughness used to make circular weirs highly affect surface roughness and, in turn, flow hydraulics passing over these structures.  in the present research, numerous experiments under different hydraulic conditions were performed on a physical model to study the effects of roughness on flow hydraulics over a circular weir. the flow hydraulics incl...