The output power produced by high-concentration solar thermal and photovoltaic systems is directly related to the amount of solar energy acquired by the system, and it is therefore necessary to track the sun's position with a high degree of accuracy. Many systems have been proposed to facilitate this task over the past 20 years. Accordingly, this paper commences by providing a high level overview of the sun tracking system field and then describes some of the more significant proposals for closed-loop and open-loop types of sun tracking systems.
Additive manufacture (AM) appears to be the most suitable technology to produce sophisticated, high quality, lightweight parts from Ti6Al4V alloy. However, the fatigue life of AM parts is of concern. In our study, we focused on a comparison of two techniques of additive manufacture—selective laser melting (SLM) and electron beam melting (EBM)—in terms of the mechanical properties during both static and dynamic loading. All of the samples were untreated to focus on the influence of surface condition inherent to SLM and EBM. The EBM samples were studied in the as-built state, while SLM was followed by heat treatment. The resulting similarity of microstructures led to comparable mechanical properties in tension, but, due to differences in surface roughness and specific internal defects, the fatigue strength of the EBM samples reached only half the value of the SLM samples. Higher surface roughness that is inherent to EBM contributed to multiple initiations of fatigue cracks, while only one crack initiated on the SLM surface. Also, facets that were formed by an intergranular cleavage fracture were observed in the EBM samples.
An experiment was conducted in rice ¢eld plots each of 30 m 2 to determine the appropriate combination of feeding and fertilization regimes for the giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879) cultured along with rice in rice ¢elds. There were four treatments: rice culture only with regular fertilization (A, control); rice^prawn integrated culture with regular fertilization (B); rice^prawn integrated culture with basal fertilization and commercial feed (C) and rice^prawn integrated culture with regular fertilization and commercial feed (D). Juvenile prawns of 1.5-g size were stocked on the third day after rice transplantation at a density of 2 prawns m À 2 and fed twice daily at 5% reducing to 2% of body weight during the experiment. The rice yield in treatment D (0.42 kg m À 2 ) was signi¢cantly higher than that in other treatments (0.34, 0.36, 0.34 kg m À 2 in treatments A, B, C respectively). Prawns grew signi¢cantly faster (Po0.05) in treatments C and D (23.8 AE 0.9 and 22.0 AE 1.7 g prawn À1 respectively) than in treatment B (14.7 AE 1.6 g prawn À1 ). Prawn production in treatment C (347 AE 13 kg ha À1 crop À1 ) was sig-ni¢cantly (Po0.05) higher than that (234 AE 30 kg ha À1 crop À1 ) in treatment B, while in treatment D (296 AE 53 kg ha À1 crop À1 ) it was not signi¢cantly di¡erent from that in treatments B and C (P40.05). Treatment C gave the highest economic returns among all treatments, followed by treatments D and B, indicating that the combination of basal fertilization and commercial feed is the most appropriate nutrient input regime for the rice^prawn integrated culture system.
A large-scale experiment on production of sand goby fry was conducted for one annual cycle at Nong-Sua Fisheries Station in Thailand. Approximately 1000 egg nests containing 25 million eggs were collected from January through October from artificial substrates. The hatching rate of fertilized eggs was approximately 80%. Fry were reared in two stages. In stage 1, the newly developed fry, with average total body length of 4 mm and mouth size opening of approx. 0.1 mm, were first fed with a combination of chicken-egg slurry and live rotifers. The survival rate for this stage ranged from 7 to 55%, with an average of 20% among batches of egg nests collected during the year. Older stage 2 fry were fed with live Moina sp., chironomid larvae, and ground raw fish from days 30 to 60. Stage 2 survival rates ranged from 60 to 99% and length increased from 2.4 to 3.8 cm. Growth rate was inversely related to stocking density at this stage. A total of 147 300 juvenile fish was produced in the l-year effort.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.