An investigation is carried out on the problem involved in 4D variational data assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint te...An investigation is carried out on the problem involved in 4D variational data assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint technology, penalty method and augmented Lagrangian method are used in constraint optimization field to minimize the defined constraint objective functions. The results of the numerical experiments show that the optimal solutions are obtained if the functions reach the minima. VDA with constraint conditions controlling the growth of gravity oscillations is efficient to eliminate perturbation and produces optimal initial field. It seems that this method can also be applied to the problem in numerical weather prediction. Key words Variational data assimilation - Constraint conditions - Penalty methods - finite-element model This research is supported by National Natural Science Foundation of China (Grant No. 49575269) and by National Key Basic Research on the Formation Mechanism and Prediction Theory of Severe Synoptic Disasters (Grant No. G1998040910).展开更多
针对传统虚假数据注入攻击将量测值与状态变量间的非线性函数关系近似作为直流模型进行处理,且未考虑交流潮流和不完整拓扑信息的问题,文章提出一种虚拟数据注入攻击(dummy data injection attack,DDIA)生成方法。首先,详细分析交流状...针对传统虚假数据注入攻击将量测值与状态变量间的非线性函数关系近似作为直流模型进行处理,且未考虑交流潮流和不完整拓扑信息的问题,文章提出一种虚拟数据注入攻击(dummy data injection attack,DDIA)生成方法。首先,详细分析交流状态评估及不良状态检测方法,为后续DDIA生成提供理论依据;其次,提出了计及交流潮流和拓扑约束的DDIA生成方法,并考虑DDIA的虚拟性特征,通过确保量测数据与被攻击数据距离最小的数据点,即可构造被篡改的量测数据;最后,在IEEE 14、IEEE 118和IEEE 300节点系统上进行攻击模拟,结果表明,提出的虚拟数据注入攻击十分隐蔽且对电力系统的稳定运行造成了严重影响。展开更多
We study the constraints on the dark energy model with constant equation of state parameter w = pip and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjectur...We study the constraints on the dark energy model with constant equation of state parameter w = pip and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjecture and the observational data gives tu 〈 -0.7 at the 3σ confidence level. The holographic dark energy model realized by a scalar field is in swampland.展开更多
基金National Natural Science Foundation of China (Grant No. 49575269) National Key Basic Research on the Formation Mechanism and
文摘An investigation is carried out on the problem involved in 4D variational data assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint technology, penalty method and augmented Lagrangian method are used in constraint optimization field to minimize the defined constraint objective functions. The results of the numerical experiments show that the optimal solutions are obtained if the functions reach the minima. VDA with constraint conditions controlling the growth of gravity oscillations is efficient to eliminate perturbation and produces optimal initial field. It seems that this method can also be applied to the problem in numerical weather prediction. Key words Variational data assimilation - Constraint conditions - Penalty methods - finite-element model This research is supported by National Natural Science Foundation of China (Grant No. 49575269) and by National Key Basic Research on the Formation Mechanism and Prediction Theory of Severe Synoptic Disasters (Grant No. G1998040910).
基金Supported by the National Natural Science Foundation of China under Grant No 10605042.
文摘We study the constraints on the dark energy model with constant equation of state parameter w = pip and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjecture and the observational data gives tu 〈 -0.7 at the 3σ confidence level. The holographic dark energy model realized by a scalar field is in swampland.
