Aluminium alloy sheets were joined to stainless steel ones by a resistance spot welding method using Al-Mg alloy interlayer. The interlayer exhibits a lower melting point than the Al alloy. Consequently, melted interlayer with a lower temperature filled the gap between the two sheets and resulted in effective joining. Subsequently, tensile shear fatigue tests had been conducted to evaluate fatigue strength and to determine the fatigue fracture mechanism. Resistance spot welding dissimilar welds exhibited higher fatigue strengths than friction stir spot welded dissimilar ones. Fatigue fracture modes were dependent on the load levels, where plug type fracture occurred at high load levels, shear fracture through the nugget at medium load levels and through thickness fatigue crack propagation in the Al sheet at low load levels. The fracture mode transition was attributed to the geometrical rotation around the nugget.

A night-time OLS (Operational Linescan System) visible± near-infrared (VNIR) channel image of the DMSP (Defense Meteorological Satellite Program) was overlaid on the simultaneously corrected OLS thermal infrared (TIR) channel image for the area around Japan. The OLS composite image showed a clear relationship between the location of ® shing¯eet lights detected by the VNIR channel and the sea surface temperature (SST) distribution observed by the TIR channel. Many ® shing¯eets were located at the cold side of the boundary area between warm currents and cold currents. Since some types of ® sh are likely to gather in certain sea temperature zones, the OLS composite image may provide useful information for the monitoring of ® shing¯eets as well as for marine resources management.

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