This paper introduces the functioning principle as well as dimensioning elements of a new active solar heating system using air as heat carrier. The air is heated in flat-plate collectors and then circulated through the building walls having circulation “hollows”. The heat storage function is performed by a rockbed storage unit. The solar collectors have water-air double service and supply the ...

It is analytically shown that the presence of submicrometer-sized air gaps between the dielectric and metal contact surfaces in a dielectric-filled metallic parallel-plate waveguide can have a dramatic effect on the guided-wave propagation of subpicosecond terahertz pulses. Through the use of metal-evaporated dielectric surfaces to overcome the imperfect contact problem, and a special air-diele...

Polyethylene wear increasingly has been blamed for osteolysis and granuloma formation after total joint arthroplasty. The authors evaluated the wear difference between bearing surfaces of stainless steel, cobalt chrome, and titanium alloy. They also compared cemented all-polyethylene molded cups with cemented metal-backed molded acetabular cups. These were compared with molded and machined poly...

We examined radiographic polyethylene wear in 233 cemented total hip arthroplasties (201 patients) with either a metal-backed or a non-metal-backed acetabular cup. All patients had identical cemented one-piece titanium femoral stems with a femoral head diameter of 28 mm. The mean linear wear rate was 0.11 mm/yr in metal-backed sockets and 0.08 mm/yr in non-metal-backed sockets (p = 0.0002). The...

The new study has been prompted by indications from researchers at Australia's Casey Station which suggest the subglacial basins could make the East Antarctic ice sheet more vulnerable in a warming world. Satellite data suggest that the Totten Glacier, which dominates the ice of the Aurora subglacial basin, appears to be losing ice at its downstream edge. " We are getting more science done with...

The performance of two evaporatively cooled heat exchangers is investigated under similar operating conditions of air flow rates and inlet hot water temperatures. The heat exchangers are plain and plate-finned circular tube types which occupy the same volume. Spray water, which is circulated in a closed circuit, is injected onto the exposed surfaces of the tubes and fins. The contact between ai...