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SINGLE PHASE PWM INVERTER WITH CURRENT MINOR CONTROL LOOP
Y.Shikano,T.Kawabata,T.Furuno,K.Honjo,N.Sashida,Y.Yamamoto 전력전자학회 1989 ICPE(ISPE)논문집 Vol.- No.-
This paper proposes a single phase sinusoidal voltage inverter with current minor loop using high speed switching devices such as Bi-MOS or IGBT.<br/> Following new methods are successfully combined and adopted to get high performance:<br/> (a) A high speed current minor control loop is given for the Inverter to constrain inverter current within SOA of switching devices, and as the reference of this current loop, following signals are given to get sinusoidal output voltage.<br/> (1) Current for the parallel element of the<br/> output filter<br/> (ii) Feedforward of the load current (iii) Voltage adjusting and stabilizing signal which is the output of voltage controller<br/> (b) Micro processor control using the dead beat algorithm is developed for sinusoidal output voltage Inverter. This system consists of two dead beat controllers for current and voltage. By using the dead beat control, the inverter current and the output voltage settle with one sampling period.
Kikuchi, Eisuke,Takagi, Shigeto,Shikano, Shuichi,Hideyuki, Doi The Korean Society of Limnology 2005 생태와 환경 Vol.38 No.S
Carbon stable isotope ratios of producers varied in lake ecosystems. In tile present study, we tried to estimate the seasonal variations of carbon isotope ratios of phytoplankton and benthic diatoms in a strongly acidic lake ecosystem. Lake Katanuma is a volcanic, strongly acidic lake (average pH of 2.2), located in Miyagi, Japan. Only two algal species dominate in Lake Katanuma; Pinnularia acidojaponica as a benthic diatom, and Chlamydomonas acidophila as a green alga. Carbon isotope values of P. acidojaponica varied seasonally, while those of particulate organic matter, which were mainly composed of C. acidophila remained fairly stable. The differences suggested that $CO_2$ gas was more frequently limited for P. acidojaponica than C. acidophila, since high density patches of benthic diatoms were sometimes observed on the lake sediment. Generally, carbon concentration mechanisms (CCMs)of microalgae can fix bicarbonate in lakes, and affect the carbon isotope values of microalgae. While, in Lake Katanuma, CCMs of the microalgae may scarcely function because of high $CO_2$ gas concentration and low pH. This is the reason for low seasonal amplitude of carbon isotope values of phytoplankton relative to those in other lakes.
Interannual Variations of Limnological and Ecological Characteristics in Acidic Lake Katanuma
Kikuchi, Eisuke,Takagi, Shigeto,Doi, Hideyuki,Shuichi, Shikano The Korean Society of Limnology 2005 생태와 환경 Vol.38 No.4
We observed the physical, chemical, and biological characteristics of an acidic lake, Lake Katanuma, from 1998 to 2002 at weekly or biweekly intervals, except during the winter. This volcanic lake has a dimictic thermal pattern. In summer, the volcanic heat supply at the lake bottom results in weak thermal stratification. In 1998, 1999, and 2002, short-term holomixis was observed during the stratification period, when the anoxic, hydrogen sulfide-rich water from the hypolimnion spread across the entire lake. In contrast, distinct short-term holomixis did not occur during the stratificatlon period in 2000 and 2001. However, the early onset of the autumn turnover in August 2000 and 2001 caused anoxic conditions to persist throughout the entire water column for more than 2 weeks. The anoxic and hydrogen sulfide-rich conditions affected population densities of chironomid larvae (Chironomus acerbiphilus) and planktonic algae (Chlamydomonas acidophila), both dominant species in Lake Katanuma. Thus, the interannual variations of limnological characteristics influenced the seasonal population changes of these species.