Nutrient loads into water resources continues to be a major problem in Southern Africa. This has resulted in significant compromises in the ecological integrity of freshwater resources. The study aimed to assess the p...Nutrient loads into water resources continues to be a major problem in Southern Africa. This has resulted in significant compromises in the ecological integrity of freshwater resources. The study aimed to assess the pollution load into the Elands River in terms of nitrates and orthophosphates. These variables were compared against the Crocodile Catchment Interim Resource Quality Objectives to determine compliances or non-compliance of the Waterval Boven wastewater treatment plant. Generally upstream nitrate levels did not exceed the ideal limit of 0.5 mg·l-1 as indicated in the 2015 to 2016 samples where values ranged between 0.32 mg·l -1 and 0.27 mg·l-1, respectively. Similarly, observed upstream orthophosphates levels were below the ideal limit of 0.03 mg·l-1. However, downstream values of both nutrients exceeded the respective set limits. The nutrient load contribution from the sewage plant was characterised by a simple point-source model. Patterns of the loads into the river were demonstrated on a load duration curve based on the river which equalled or exceed 0.18 m3/s upstream and 1.31 m3/s downstream at 90% of the time. However, the flows were regarded as significantly low to deal with uncontrolled pollution loads. Most of the observed loads fell below the ideal limit of 0.05 mg·l-1 for nitrates both upstream and downstream of the sewage plant. For orthophosphates, most of the upstream loads were below the tolerable limit of 0.1 mg·l-1 whilst the downstream loads were exceeding the tolerable limits. The higher loads downstream in the river were attributed to the sewage discharge from the Waterval Boven wastewater treatment plant and the low river flows. Hence it could be concluded that river water quality should be interpreted based on the river flow regime in a given season.展开更多
等效电量函数法是电力系统随机生产模拟的实用高效方法,但在计算失负荷概率(Loss Of Load Probability,LOLP)指标时可能存在精度不高的问题。利用实际电力系统中持续负荷曲线的台阶状特征,引入基准单位将拐点横坐标整数化,提出了用于电...等效电量函数法是电力系统随机生产模拟的实用高效方法,但在计算失负荷概率(Loss Of Load Probability,LOLP)指标时可能存在精度不高的问题。利用实际电力系统中持续负荷曲线的台阶状特征,引入基准单位将拐点横坐标整数化,提出了用于电力系统随机生产模拟的稀疏卷积递推法。该方法采用变宽度矩形描述持续负荷曲线,充分利用了拐点横坐标在整数空间中分布的稀疏性,计算时间对基准单位的取值不敏感,比较适用于系统规模较大、对LOLP指标计算精度要求较高的场合。最后通过对IEEE-RTS79系统及其修正和扩大系统的仿真测试验证了所提方法的准确性及效率。展开更多
文摘Nutrient loads into water resources continues to be a major problem in Southern Africa. This has resulted in significant compromises in the ecological integrity of freshwater resources. The study aimed to assess the pollution load into the Elands River in terms of nitrates and orthophosphates. These variables were compared against the Crocodile Catchment Interim Resource Quality Objectives to determine compliances or non-compliance of the Waterval Boven wastewater treatment plant. Generally upstream nitrate levels did not exceed the ideal limit of 0.5 mg·l-1 as indicated in the 2015 to 2016 samples where values ranged between 0.32 mg·l -1 and 0.27 mg·l-1, respectively. Similarly, observed upstream orthophosphates levels were below the ideal limit of 0.03 mg·l-1. However, downstream values of both nutrients exceeded the respective set limits. The nutrient load contribution from the sewage plant was characterised by a simple point-source model. Patterns of the loads into the river were demonstrated on a load duration curve based on the river which equalled or exceed 0.18 m3/s upstream and 1.31 m3/s downstream at 90% of the time. However, the flows were regarded as significantly low to deal with uncontrolled pollution loads. Most of the observed loads fell below the ideal limit of 0.05 mg·l-1 for nitrates both upstream and downstream of the sewage plant. For orthophosphates, most of the upstream loads were below the tolerable limit of 0.1 mg·l-1 whilst the downstream loads were exceeding the tolerable limits. The higher loads downstream in the river were attributed to the sewage discharge from the Waterval Boven wastewater treatment plant and the low river flows. Hence it could be concluded that river water quality should be interpreted based on the river flow regime in a given season.
文摘等效电量函数法是电力系统随机生产模拟的实用高效方法,但在计算失负荷概率(Loss Of Load Probability,LOLP)指标时可能存在精度不高的问题。利用实际电力系统中持续负荷曲线的台阶状特征,引入基准单位将拐点横坐标整数化,提出了用于电力系统随机生产模拟的稀疏卷积递推法。该方法采用变宽度矩形描述持续负荷曲线,充分利用了拐点横坐标在整数空间中分布的稀疏性,计算时间对基准单位的取值不敏感,比较适用于系统规模较大、对LOLP指标计算精度要求较高的场合。最后通过对IEEE-RTS79系统及其修正和扩大系统的仿真测试验证了所提方法的准确性及效率。
