The 1966 flood on the Ynisei River at the Krasnoyarsk hydroelectric project site

Considered as a source of renewable energy, wave is a resource featuring high variability at all time scales. Furthermore wave climate also changes significantly from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period at the project site. In this paper we show that optimizing the device necessitates accounting for all possible wave conditions weighted by their annual occurrence frequency, as generally given by the classical wave climate scatter diagrams. A generic and very simple wave energy converter is considered here. It is shown how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the productive motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three sites with very different wave climate.

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Comparison of Superpave and Marshall Mixtures for Low-Volume Roads and Shoulders

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1609-06 ◽

1998 ◽

Vol 1609 (1) ◽

pp. 44-50 ◽

Cited By ~ 7

Author(s):

Affan Habib ◽

Mustaque Hossain ◽

Rajesh Kaldate ◽

Glenn Fager

Keyword(s):

Mix Design ◽

River Sand ◽

Low Volume Roads ◽

Superpave Gyratory Compactor ◽

Asphalt Content ◽

Low Volume ◽

Project Site ◽

Axle Loads ◽

Crushed Limestone ◽

Asphalt Film

Superpave and Marshall mix designs using local aggregates were done to study the suitability of the Superpave mix design as compared with the Marshall mix design for low-volume roads, especially shoulders. The project site was Kansas Route 177 in northeast Kansas. Three locally available aggregates, crushed limestone and coarse and fine river sands, were used in this study. Five blends with varying proportions of coarse and fine river sands were selected. Mix samples were compacted in the Superpave gyratory compactor with the applicable number of gyrations and were compacted with the Marshall hammer by using 50 blows per face. Bulk densities of the compacted samples and maximum specific gravities of loose samples also were measured for each blend. The results show that the Superpave mix design for low-volume roads and shoulders results in lower estimated asphalt content than does the Marshall method. The required asphalt content increases as the proportion of coarse river sand increases in the mix. Superpave requirements for the voids filled with asphalt (VFA) for low-volume traffic, that is, less than 0.3 million equivalent single-axle loads, appeared to be too high. High asphalt film thicknesses were computed for the mixtures that did not meet the Superpave VFA requirements. Lowering the design number of gyrations (Ndes) for compaction of samples would result in increased asphalt requirement for the Superpave mixture with a given gradation.

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Optimization of a Weld Overlay on a Plate Structure

Journal of Pressure Vessel Technology ◽

10.1115/1.4000511 ◽

2009 ◽

Vol 132 (1) ◽

Cited By ~ 1

Author(s):

John Goldak ◽

Mahyar Asadi ◽

Jianguo Zhou ◽

Stanislav Tchernov ◽

Dan Downey

Keyword(s):

Welding Process ◽

Francis Turbine ◽

Transient Temperature ◽

Weld Repair ◽

Weld Overlay ◽

Hydroelectric Project ◽

Repair Procedure ◽

Strain Stress ◽

Welding Direction ◽

Interpass Temperature

An overlay weld repair procedure on a 1066.8×1066.8 mm2 square plate 25.4 mm thick was simulated to compute the 3D transient temperature, microstructure, strain, stress, and displacement of the overlay weld repair procedure. The application for the overlay was the repair of cavitation erosion damage on a large Francis turbine used in a hydroelectric project. The overlay weld consisted of a 4×6 pattern of 100×100 mm2 squares. Each square was covered by 15 weld passes. Each weld pass was 100 mm long. The total length of weld in the six squares was 36 m. The welds in each square were oriented either front-to-back or left-to-right. The welding process was shielded metal arc. The analysis shows that alternating the welding direction in each square produces the least distortion. A delay time of 950 s between the end of one weld pass and the start of the next weld pass was imposed to meet the requirement of a maximum interpass temperature to 50°C.

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