An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCl and 0.000 5 mol L-l Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized ...An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCl and 0.000 5 mol L-l Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized water, possibly through slow jarosite hydrolysis. Acid release through jarosite hydrolysis was greatly enhanced by Ca(OH)2 extraction at the expense of the added OH- being neutralized by the acid released. Successive extraction of the sample with KCl removed the largest amounts of acidity from the sample. However, it is likely that the major form of acidity released by KCl extraction was exchangeable acidity. The results also show the occurrence of low or non charged Al and Fe species in water and Ca(OH)2 extracts after first a few extractions. It appears that such a phenomenon was related to a decreasing EC value with increasing number of extractions.展开更多
Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electri...Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.展开更多
文摘An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCl and 0.000 5 mol L-l Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized water, possibly through slow jarosite hydrolysis. Acid release through jarosite hydrolysis was greatly enhanced by Ca(OH)2 extraction at the expense of the added OH- being neutralized by the acid released. Successive extraction of the sample with KCl removed the largest amounts of acidity from the sample. However, it is likely that the major form of acidity released by KCl extraction was exchangeable acidity. The results also show the occurrence of low or non charged Al and Fe species in water and Ca(OH)2 extracts after first a few extractions. It appears that such a phenomenon was related to a decreasing EC value with increasing number of extractions.
基金The authors would like to acknowledge the financial support from University of Malaya,Impact Oriented Interdisciplinary Research Grant(Project:IIRG015B-2019)to carry out this research.
文摘Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.
