一类二阶微分方程Poincaré分岔极限环的不存在性

讨论一类二阶微分方程x¨+εf(x,x.)x.+g(x)=0的Poincar分岔极限环的不存在性,利用一阶Mel’nikov函数直接从整体上进行分析讨论,得出了若干充分条件和判别准则。     

Transforming the Spanish military

The article analyses the Spanish military transformation. This process started in 2004 as a means to adapt the force structure, organization and capabilities of the Spanish military to meet present and future threats in compliance with NATO’s initiatives, thus ensuring the continuity of the equipment modernization, professionalization and the adjustment of the country’s defence architecture to the post-cold war environment. A decade later, although transformation is still a priority for the Ministry of Defence, limited political will, a lack of strategic guidance, poor resource management and the effects of the economic crisis are compromising its development. This article describes the Spanish military transformation and assesses its value in adapting the country’s armed forces to the current and prospective security environment.     

常微分方程数值计算导数权重法

提出一个新的单步法 ,它对导数取权重平均值代替算术平均值 .其计算结果与真实值吻合很好 ,计算量小