Solar air collectors can be used for heating rooms, drying crops and wood, and heating water. In present studies, first, a flow control system for obtaining a constant temperature at the exit of a flat-plate collector was installed in a hot air supply system and the feasibility of the control system was examined. When the flow temperature was lower than the temperature that was set by a digital indicating controller, the fan power was reduced to decrease the flow rate. When the outlet air temperature was higher than the setting temperature, the flow rate was increased. Consequently, the control system worked well to maintain the exit air temperature. Secondly, an unsteady state analysis was made on thermal performance of the collector. In analysis, flow rate variations over time were given as conditions. Validity of this analysis was checked by experimentation. Analytical results agreed well even when solar radiation intensity, wind speed, or flow rate changed abruptly.

Promotion of the use of renewable energy, such as solar heat, for space heating and drying crops and wood is desired to prevent global warming. High-temperature collection of heat by air collectors producing as much as 50°C in winter for space heating and about 80°C in summer for exchanging heat to circulating water for hot water supply would be appropriate applications. In this study, first, a flow control system for constant outlet temperature was installed in a hot air supply system to examine the feasibility of the control system. After experiments, it was found that the control system could function satisfactory. Second, an unsteady-state analysis was made to predict the thermal performance of a flat-plate collector under a given condition of variable flow rate. The analytical model became simple by the assumptions that the heat capacity of the air in the collector and heat conduction in the flow direction through the air and the materials of the collector could be neglected. The maximum differences in outlet temperature and collector efficiency for constant flow rate between the analysis and the experiment were 1.8°C and 6% of the collector efficiency, respectively, except in the beginning of experiments. The biggest difference in the collector efficiency was 30% at 3:00 P.M., which occurred at the end of one of the experiments. The analytical results generally agreed well with the experimental results even when the flow rate and solar radiation changed greatly as time went on. Transient effects are important to predict outlet temperature for variable solar radiation intensity, wind speed, and flow rate.

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ABSTRACT. A microbial culture was prepared by co-cultivation of Lactobacillus paracasei, Pichia membranifaciens and Saccharomyces cereviciae for 48 hr at 30C in rice bran extract medium, supplemented with dextrose. Oral administration of the resulting non-viable heat-inactivated microbial culture to common carp, Cyprinus carpio L., delivered in feed for four weeks, induced effective protection against experimental atypical Aeromonas salmonicida infection which causes "ulcer disease". After challenge of the carp by immersion, fish mortality and development of skin lesions such as hemorrhages and ulcers were significantly suppressed in carp treated with mixed microbial culture adsorbed on dry pellets relative to carp treated with medium or without extract. Atypical A. salmonicida was re-isolated from ulcerative lesions in parts of dead and surviving fish, but Aeromonas hydrophila and Flavobacterium sp. were also isolated from these fish, verifying microbial population changes during the progression of skin lesions. Among interleukin-1 (IL-1), tumor necrosis factor-, as well as CXC- and CXC- chemokines, gene expression of IL-1 was up regulated in the spleen and head kidney three weeks after administration of the mixed microbial culture. These results clearly show that this mixed microbial culture, delivered in feed, is effective in preventing A. salmonicida disease in carp.

Over the last few years, electro-optic (EO) polymers have reached the state of technological maturity where devices for practical applications become feasible. For example, polymers with EO coefficients stable up to 300°C' and r33 coefficients of 55 pm/V2 have been discovered recently. The ease with which polymers can be processed into multilayer devices by standard Si processing techniques makes them attractive for optoelec-