The Soil and Water Assessment Tool (SWAT) is a versatile model presently used worldwide to evaluate water quality and hydrological concerns under varying land use and environmental conditions. In this study, SWAT was ...The Soil and Water Assessment Tool (SWAT) is a versatile model presently used worldwide to evaluate water quality and hydrological concerns under varying land use and environmental conditions. In this study, SWAT was used to simulate streamflow and to estimate sediment yield and nutrients loss from the Murchison Bay catchment as a result of land use changes. The SWAT model was calibrated and validated for streamflow for extended periods. The Sequential Uncertainty Fitting (SUFI-2) global sensitivity method within SWAT Calibration and Uncertainty Procedures (SWAT-CUP) was used to identify the most sensitive streamflow parameters. The model satisfactorily simulated stream discharge from the catchment. The model performance was determined with different statistical methods. The results showed a satisfactory model streamflow simulation performance. The results of runoff and average upland sediment yield estimated from the catchment showed that, both have increased over the period of study. The increasing rate of runoff can lead to severe and frequent flooding, lower water quality and reduce crop yield in the catchment. Therefore, comprehensive water management steps should be taken to reduce surface runoff in the catchment. This is the first time the SWAT model has been used in the Murchison Bay catchment. The results showed that, if all uncertainties are minimised, a well calibrated SWAT model can generate reasonable hydrologic simulation results in relation to land use, which is useful to water and environmental resources managers and policy and decision makers.展开更多
平方公里阵列(Square Kilometre Array,SKA)射电望远镜的数据处理是通过管线方式进行的,管线的执行效率是SKA区域中心考虑的重要因素.连续谱成像观测是SKA的主要观测模式之一,也是许多科学工作的基础.本文以SKA低频先导设备(Murchison W...平方公里阵列(Square Kilometre Array,SKA)射电望远镜的数据处理是通过管线方式进行的,管线的执行效率是SKA区域中心考虑的重要因素.连续谱成像观测是SKA的主要观测模式之一,也是许多科学工作的基础.本文以SKA低频先导设备(Murchison Widefield Array,MWA)的成像管线为例,在中国SKA区域中心原型机(China SKA Regional Centre Prototype,CSRC-P)上进行并行处理管线优化.以往的优化方案都集中在少数性能热点,缺乏对整体管线的系统优化,导致整体加速比相对较低.针对这一问题,本文提出一种全局优化方案,针对管线使用多种编程语言和图像数据可独立处理的特点,综合使用C++多线程、Python多进程和Shell多任务并行等优化方法,并验证了优化结果的准确性.实验表明,优化后的代码在CSRC-P的x86节点和ARM(Advanced RISC Machine)节点上分别获得了2.7和2.4倍加速,运行时间分别从7479和9666 s,降低为2759和4061 s.ARM计算节点展现出对SKA应用良好的适应性.本文的优化策略和方法也适用于其他SKA科学应用,对SKA先导望远镜的科学运行和未来的运行也有帮助.展开更多
平方公里阵列(Square Kilometre Array, SKA)将成为世界上最大的综合孔径射电望远镜.凭借其高分辨率、超高灵敏度和超快巡天速度, SKA能以前所未有的细节探索宇宙.连续谱巡天是SKA的几个主要观测模式之一,为理解和认识射电天空奠定基础....平方公里阵列(Square Kilometre Array, SKA)将成为世界上最大的综合孔径射电望远镜.凭借其高分辨率、超高灵敏度和超快巡天速度, SKA能以前所未有的细节探索宇宙.连续谱巡天是SKA的几个主要观测模式之一,为理解和认识射电天空奠定基础. SKA探路者设备已经运行了几年,积累了丰富的巡天观测数据.中国天文学家正在为中国SKA区域中心(China SKA Regional Centre, CSRC)的建设进行积极的准备,已经完成了原型机.本文详细介绍了在CSRC原型机中部署SKA低频数据处理系统的进展.默奇森宽场阵列(Murchison Wide-field Array, MWA)是SKA低频阵列的先导项目.我们使用MWA的观测数据来验证成像管线系统的部署并测试其正确性. CSRC原型机的数据处理结果与已发表的结果一致,表明在CSRC原型机上部署开发的并行数据处理系统取得了巨大成功.而且,该原型机的灵活适配性和可扩展性使其可以轻松扩展,支持未来SKA第一阶段试运行期间的大规模连续谱成像实验.这些经验将有助于改善成像管线系统,并有助于完善CSRC.展开更多
文摘The Soil and Water Assessment Tool (SWAT) is a versatile model presently used worldwide to evaluate water quality and hydrological concerns under varying land use and environmental conditions. In this study, SWAT was used to simulate streamflow and to estimate sediment yield and nutrients loss from the Murchison Bay catchment as a result of land use changes. The SWAT model was calibrated and validated for streamflow for extended periods. The Sequential Uncertainty Fitting (SUFI-2) global sensitivity method within SWAT Calibration and Uncertainty Procedures (SWAT-CUP) was used to identify the most sensitive streamflow parameters. The model satisfactorily simulated stream discharge from the catchment. The model performance was determined with different statistical methods. The results showed a satisfactory model streamflow simulation performance. The results of runoff and average upland sediment yield estimated from the catchment showed that, both have increased over the period of study. The increasing rate of runoff can lead to severe and frequent flooding, lower water quality and reduce crop yield in the catchment. Therefore, comprehensive water management steps should be taken to reduce surface runoff in the catchment. This is the first time the SWAT model has been used in the Murchison Bay catchment. The results showed that, if all uncertainties are minimised, a well calibrated SWAT model can generate reasonable hydrologic simulation results in relation to land use, which is useful to water and environmental resources managers and policy and decision makers.
文摘平方公里阵列(Square Kilometre Array,SKA)射电望远镜的数据处理是通过管线方式进行的,管线的执行效率是SKA区域中心考虑的重要因素.连续谱成像观测是SKA的主要观测模式之一,也是许多科学工作的基础.本文以SKA低频先导设备(Murchison Widefield Array,MWA)的成像管线为例,在中国SKA区域中心原型机(China SKA Regional Centre Prototype,CSRC-P)上进行并行处理管线优化.以往的优化方案都集中在少数性能热点,缺乏对整体管线的系统优化,导致整体加速比相对较低.针对这一问题,本文提出一种全局优化方案,针对管线使用多种编程语言和图像数据可独立处理的特点,综合使用C++多线程、Python多进程和Shell多任务并行等优化方法,并验证了优化结果的准确性.实验表明,优化后的代码在CSRC-P的x86节点和ARM(Advanced RISC Machine)节点上分别获得了2.7和2.4倍加速,运行时间分别从7479和9666 s,降低为2759和4061 s.ARM计算节点展现出对SKA应用良好的适应性.本文的优化策略和方法也适用于其他SKA科学应用,对SKA先导望远镜的科学运行和未来的运行也有帮助.
文摘平方公里阵列(Square Kilometre Array, SKA)将成为世界上最大的综合孔径射电望远镜.凭借其高分辨率、超高灵敏度和超快巡天速度, SKA能以前所未有的细节探索宇宙.连续谱巡天是SKA的几个主要观测模式之一,为理解和认识射电天空奠定基础. SKA探路者设备已经运行了几年,积累了丰富的巡天观测数据.中国天文学家正在为中国SKA区域中心(China SKA Regional Centre, CSRC)的建设进行积极的准备,已经完成了原型机.本文详细介绍了在CSRC原型机中部署SKA低频数据处理系统的进展.默奇森宽场阵列(Murchison Wide-field Array, MWA)是SKA低频阵列的先导项目.我们使用MWA的观测数据来验证成像管线系统的部署并测试其正确性. CSRC原型机的数据处理结果与已发表的结果一致,表明在CSRC原型机上部署开发的并行数据处理系统取得了巨大成功.而且,该原型机的灵活适配性和可扩展性使其可以轻松扩展,支持未来SKA第一阶段试运行期间的大规模连续谱成像实验.这些经验将有助于改善成像管线系统,并有助于完善CSRC.
