Development of transition mat scour protection design methodology and comparison to the state-of-the-practice
2011 annual AGU hydrology days was held at Colorado State University on March 21 - March 23, 2011.
Hydraulic Design of Energy Dissipators for Culverts and Channels
This aid to selecting and designing an energy dissipator wihch will meet the requirements indicated by an erosion hazard assessment, details the design concept, and the erosion hazards, and discusses such aspects as culvert outlet velocity, velocity modification, flow transitions and the erosion of culvert outlets. Forced hydraulic jump and increased resistance, and details of impact basins, drop structures, stilling wells and riprap are also discussed. Preliminary energy dissipator selection is made by comparing the input constraints or design criteria flow regime, debris problems, location, channel characteristics, allowable scour, etc., with the attributes of the various energy distributiors. The attributes of individual dissipators include: Froude number (Fr) range for best performance; discharge velocity or other limitations; possible maintenance; operational or location problems; maximum size; and limiting features such as culvert slope or shape. Dissipator designs fall into 2 general groups: those with Fr less than 3 (most designs are in this group), and those with Fr greater than 3. The designs are treated as illustrated by the conceptual models, and are related to actual situations through example problems.
Microstructure of the solder-casting zone in bridges of dental gold alloys.
The composition and structure were studied in the cast and in the solder of bridges which had failed clinically. Both materials were gold alloys but with different contents of Pt, Ag and Zn. The metallographic investigation revealed defects mostly in the solder, situated in the subsurface layer. SEM studied of the fracture surface revealed large porosites and a structure of dense parallel lines--striations--, indicating that the material had failed from fatigue. The materials in the fractured bridges were identified by micro-probe measurements. It was stated that cast material and solder material used together, were of different composition.