随着高科技园区等用户对供电可靠性要求的提高,环形配电网成为一种发展趋势。与射线型配电网相似,由功率因数校正电容和系统自身电感导致的谐波谐振现象,使得环形配电网中的谐波污染问题成为人们关注的焦点之一。该文针对环形配电网中...随着高科技园区等用户对供电可靠性要求的提高,环形配电网成为一种发展趋势。与射线型配电网相似,由功率因数校正电容和系统自身电感导致的谐波谐振现象,使得环形配电网中的谐波污染问题成为人们关注的焦点之一。该文针对环形配电网中谐波谐振现象,基于将环形配电网等效为射线型配电网的基本思想,提出一种在环形配电网中点安装等效无限长有源电力滤波器(infinite active power filter,I-APF)的谐波抑制方案。相比于在环形配电网中点安装阻性有源电力滤波器(resistive active power filter,R-APF)的传统方案,该方案不仅能够获得更好的谐波抑制效果;同时,该方案对于安装位置的改变、电容的改变和非线性负载的改变,均具有更好的适应性和谐波抑制效果。仿真分析和实验结果均验证了该方案的正确性和有效性。展开更多
Spermonde Archipelago has been found to have a high sponge biodiversity. Sponges that have feeding behavior as filter feeder can be exposed to heavy metals, including Zn metal. Zn is an essential metal that is physiol...Spermonde Archipelago has been found to have a high sponge biodiversity. Sponges that have feeding behavior as filter feeder can be exposed to heavy metals, including Zn metal. Zn is an essential metal that is physiologically needed by sponge to catalyze chemical reactions and generally operates on enzymes. A study on Zn pollution level in Spermonde Archipelago from zone I to Zone IV was conducted by analyzing Zn concentration in sponges, sediments, and seawater. Physicochemical parameters measurement in Spermonde Archipelago indicates that Spermonde Archipelago meets the requirements for sponge growth. Callyspongia aerizusa can be used as metal pollution indicator because this sponge can accumulate heavy metal Zn in high level (99.30 mg/kg dry weight). This sponge was derived from Kondingareng Lompo island at zone III. In addition, Kodingareng Lompo island waters had the highest Zn concentration compared to other islands. Sediments from Lae-Lae island at zone I had the highest Zn metal concentration. Lae-Lae island is the nearest island to Makassar coastal line.展开更多
Wild collection management and farming of the mangrove oyster (Crassostrea gasar) occurring widely at the Benin (West Africa) coastal zone require knowledge on the feeding ecology to explore energy sources and nutriti...Wild collection management and farming of the mangrove oyster (Crassostrea gasar) occurring widely at the Benin (West Africa) coastal zone require knowledge on the feeding ecology to explore energy sources and nutritional needs. Six hundred thirty (630) individuals of C. gasar have been sampled in the rearing site at the Benin coastal lagoon to investigate on the trophic ecology of this cultivated bivalve. The diet analysis revealed that C. gasar is a filter-feeder foraging mainly on phytoplankton (72.70%) and substrate particles (22.95%). This trophic specialization results from anatomical structure, mainly the presence of gills which facilitate the filtering of number of plankton taxa. Dominant phytoplanktons ingested comprised of Diatomophycea (33.52%), Chlorophycae (17.19%), Scenedesmacae (13.80%), Dictyosphaeriacae (3.79%), and Pleurococcacae (2.75%). Eight genuses of phytoplankton, Polycystis, Coelosphaerium, Protococcus, Botryoccocus, Crucigenia, Melosira, Cyclotella, and Gyrosigma dominated the diet of C. gasar with aggreated volumetric proportions reaching 69.06% of the diet. Higher occurrences were recorded mainly for Melosira occurring in 263 (41.75%) stomachs, substrate particles in 211 (33.49%), and Polycystis in 151 (23.97%). C. gasar exhibited a high niche breadths varying from 4.54 to 5.78, suggesting that this bivalve consumed a high variety of food items, thus exhibiting a degree of trophic plasticity. Diet overlaps (?jk) among different size classes were high and varied from 0.71 to 0.98, indicating an ontogenetic diet shift pattern in C. gasar. Probably, to adapt to the benthic-muddy environment and to increase survival, C. gasar has evolved a specialized feeding mechanism and strategy to retrieve only needed nutrients for growth and to reject awful and nondigestible foods. Also, at the oyster rearing grounds, there is an evidence of shift in the food web structure leading to an increase of the biological productivity at the coastal zone. The output from this study is a valuable documentation for the sustainable development of oyster aquaculture, wild stock management and conservation. However, further scientific knowledge on nutritional needs, phytoplankton toxicity and habitat degradation, and improvement of farming techniques are required for an integrated oyster management.展开更多
文摘随着高科技园区等用户对供电可靠性要求的提高,环形配电网成为一种发展趋势。与射线型配电网相似,由功率因数校正电容和系统自身电感导致的谐波谐振现象,使得环形配电网中的谐波污染问题成为人们关注的焦点之一。该文针对环形配电网中谐波谐振现象,基于将环形配电网等效为射线型配电网的基本思想,提出一种在环形配电网中点安装等效无限长有源电力滤波器(infinite active power filter,I-APF)的谐波抑制方案。相比于在环形配电网中点安装阻性有源电力滤波器(resistive active power filter,R-APF)的传统方案,该方案不仅能够获得更好的谐波抑制效果;同时,该方案对于安装位置的改变、电容的改变和非线性负载的改变,均具有更好的适应性和谐波抑制效果。仿真分析和实验结果均验证了该方案的正确性和有效性。
文摘Spermonde Archipelago has been found to have a high sponge biodiversity. Sponges that have feeding behavior as filter feeder can be exposed to heavy metals, including Zn metal. Zn is an essential metal that is physiologically needed by sponge to catalyze chemical reactions and generally operates on enzymes. A study on Zn pollution level in Spermonde Archipelago from zone I to Zone IV was conducted by analyzing Zn concentration in sponges, sediments, and seawater. Physicochemical parameters measurement in Spermonde Archipelago indicates that Spermonde Archipelago meets the requirements for sponge growth. Callyspongia aerizusa can be used as metal pollution indicator because this sponge can accumulate heavy metal Zn in high level (99.30 mg/kg dry weight). This sponge was derived from Kondingareng Lompo island at zone III. In addition, Kodingareng Lompo island waters had the highest Zn concentration compared to other islands. Sediments from Lae-Lae island at zone I had the highest Zn metal concentration. Lae-Lae island is the nearest island to Makassar coastal line.
文摘Wild collection management and farming of the mangrove oyster (Crassostrea gasar) occurring widely at the Benin (West Africa) coastal zone require knowledge on the feeding ecology to explore energy sources and nutritional needs. Six hundred thirty (630) individuals of C. gasar have been sampled in the rearing site at the Benin coastal lagoon to investigate on the trophic ecology of this cultivated bivalve. The diet analysis revealed that C. gasar is a filter-feeder foraging mainly on phytoplankton (72.70%) and substrate particles (22.95%). This trophic specialization results from anatomical structure, mainly the presence of gills which facilitate the filtering of number of plankton taxa. Dominant phytoplanktons ingested comprised of Diatomophycea (33.52%), Chlorophycae (17.19%), Scenedesmacae (13.80%), Dictyosphaeriacae (3.79%), and Pleurococcacae (2.75%). Eight genuses of phytoplankton, Polycystis, Coelosphaerium, Protococcus, Botryoccocus, Crucigenia, Melosira, Cyclotella, and Gyrosigma dominated the diet of C. gasar with aggreated volumetric proportions reaching 69.06% of the diet. Higher occurrences were recorded mainly for Melosira occurring in 263 (41.75%) stomachs, substrate particles in 211 (33.49%), and Polycystis in 151 (23.97%). C. gasar exhibited a high niche breadths varying from 4.54 to 5.78, suggesting that this bivalve consumed a high variety of food items, thus exhibiting a degree of trophic plasticity. Diet overlaps (?jk) among different size classes were high and varied from 0.71 to 0.98, indicating an ontogenetic diet shift pattern in C. gasar. Probably, to adapt to the benthic-muddy environment and to increase survival, C. gasar has evolved a specialized feeding mechanism and strategy to retrieve only needed nutrients for growth and to reject awful and nondigestible foods. Also, at the oyster rearing grounds, there is an evidence of shift in the food web structure leading to an increase of the biological productivity at the coastal zone. The output from this study is a valuable documentation for the sustainable development of oyster aquaculture, wild stock management and conservation. However, further scientific knowledge on nutritional needs, phytoplankton toxicity and habitat degradation, and improvement of farming techniques are required for an integrated oyster management.
