This paper examined actual farmers’ cultivation practices of NERICA (New Rice for Africa) and the determinants of its yield, based on data obtained from a field survey conducted in central Uganda. NERICA’s high yielding potential was realized in farmers’ fields. On average, farmers attained yield as high as 3 t ha-1. A high seeding rate, high fertilizer/chemical applications and high laborintensity characterized the upland NERICA cultivation in the study area. The estimation of yield function revealed that the response of rice yield to nitrogen was as high as 46 kg ha-1 of paddy per 1 kg ha-1 of nitrogen applied, and that the continuous planting reduced the yield significantly. The large difference in the unit yield between large and small farmers was explained by small farmers’ higher input intensities than large farmers’, and it is the high labor requirement of NERICA that makes it a pro-smallholder technology.
The decomposition of CF 4 using pulsed-electron-beam-generated atmospheric-pressure nonthermal nitrogen plasmas (CF 4 900 ppm, 130 kPa) is demonstrated. A high energy efficiency was obtained in the destruction and removal of CF 4 compared with the results obtained using dielectric-barrier-discharge plasmas. The results are mainly attributed to the enhanced decomposition of CF 4 by nitrogen ions that are efficiently generated by high-energy electron beams. The scavenging of reactive intermediates from the plasma without producing hydrogen fluoride is also attempted and its validity is discussed.
In the image formation performance of an underwater acoustic lens, the use of geometrical skew ray analysis for usually use in optical lens design field was examined. We measured acoustic pressure fields through a single lens, from which the acoustic energy distribution was obtained by using encircled energy. On the other hand, the analyzed acoustic energy distribution was evaluated by geometrical skew ray analysis under the measurement condition including the apodization of the source and effect of water temperature. We compared the measured and analyzed convergence positions, which the diameter of 80% of total amount of acoustic energy is the minimum. Then the both convergence positions correspond. As a result, it was shown that the image performance evaluation of a wide-view acoustic lens by geometrical skew ray analysis is useful.
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