PV System With Reconnection to Improve Output Under Nonuniform Illumination

Photovoltaic (PV) systems are often nonuniformly illuminated owing to shadows of neighboring buildings, trees, clouds, etc. In order to reduce the effect of shadows on solar panels, we propose the concept of a PV system with reconnection; this system consists of PV arrays that can be reconnected to minimize the mismatch loss, depending on the output of each of its module, measured at regular time intervals. In this study, the relationship between the output improvement with reconnection and the switching interval is shown. For a 3-kW PV system, under conditions of cloudlessness and cloudiness, a sharp difference in the output improvement relative to the switching interval is not observed. However, under the condition of shading, the output improvement sharply decreases relative to the switching interval; the output improvement at a 1-min switching interval is 0.15 kWh·h (+22.4%). For the 90-kW building-integrated photovoltaic system, during the summer solstice, a sharp difference in the output improvement relative to the switching interval is not observed. However, during the vernal equinox and winter solstice, when a large area of the PV system is shaded for a long period of time, the output improvement sharply decreases relative to the switching interval. The output improvement at a 1-min switching interval is 6.5 kWh·d (+2.9%) during the vernal equinox and 2.3 kWh·d (+3.7%) during winter solstice

Different expressions of trypsin and chymotrypsin in relation to growth in Atlantic salmon (Salmo salar L.)

The expressions of trypsin and chymotrypsin in the pyloric caeca of Atlantic salmon (Salmo salar L.) were studied in three experiments. Two internal (trypsin phenotypes, life stages) and three common external factors (starvation, feeding, temperatures) influencing growth rates were varied. Growth was stimulated by increased temperature and higher feeding rate, and it was depressed during starvation. The interaction between trypsin phenotype and start-feeding temperature affected specific activity of trypsin, but not of chymotrypsin. Trypsin specific activity and the activity ratio of trypsin to chymotrypsin (T/C ratio) increased when growth was promoted. Chymotrypsin specific activity, on the other hand, increased when there was a reduction in growth rate whereas fish with higher growth had higher chymotrypsin specific activity resulting in lower T/C ratio value. During a rapid growth phase, trypsin specific activity did not correlate with chymotrypsin specific activity. On the other hand, a relationship between specific activities of trypsin and chymotrypsin could be observed when growth declined, such as during food deprivation. Trypsin is the sensitive key protease under conditions favouring growth and genetically and environmentally affected, while chymotrypsin plays a major role when growth is limited or depressed. Trypsin specific activity and the T/C ratio value are shown to be important factors in the digestion process affecting growth rate, and could be applicable as indicators for growth studies of fish in captive cultures and in the wild, especially when food consumption rate cannot be measured

Habitats of small pelagic fish

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Feeding habits of stone flounder Platichthys bicoloratus larvae in Mutsu Bay, Japan

To clarify the feeding strategy of pelagic larvae of stone flounder in Mutsu Bay, the dietary composition and prey size was investigated from February to April during 1989–1999. Diets were compared with the numerical and volumetric compositions and frequency of occurrence of each prey species. Mensuration formulae were applied to estimate individual prey volume in the diet, while the length of planktonic species was measured from net and water samples. Prey shapes were assumed as sphere, cylinder, ellipsoid, pyramid, two elliptical cones, or a combination of ellipsoid and cylinder. Prey-size range increased as the larvae grew. Preflexion larvae fed mainly on copepod nauplii. Flexion and postflexion larvae ingested primarily appendicularians, with a suggestion that these larvae might depend on some parts of the microbial food web. Low frequencies of flexion and postflexion larvae with empty guts (1.7 and 1.4%, respectively) might be derived from feeding on slow-swimming appendicularians. From a size comparison between 'house'-like organ length and trunk length of the appendicularian Oikopleura sp., almost all house-like organs with trunks in the larval diet were nonexpanded 'house rudiments', not expanded 'houses'. Thus, stone flounder larvae may not chew the houses, but swallow the house rudiments with trunks