黑河中上游地区最高、最低气温非对称变化的时空特征分析

运用气候倾向率、趋势系数法、复值Morlet小波及Mann-kendall突变检测等方法,对黑河中上游地区1960-2009年最高、最低气温非对称变化的时空特征进行了分析．结果表明,近50a来,年和四季的平均最高、最低气温均呈明显增温趋势,最低气温空间上表现为由西北向东南方向依次递增,最高气温在流域东部和西南部为强增温区．年平均最高气温变化的突变点为1994年,最低气温变化的突变点为1989年．黑河中上游地区最高气温年变化具有明显的14a振荡周期,而最低气温主振荡周期为12a．     

蕴含强(p,q)哈密尔顿性的几个条件

利用路收缩技术,证明了,如果有向图D满足下列条件中的任何一个,(1)最小半度δ0(D)≥(n+p+q)/2;(2)D是(p+q+1)强连通有向图,且d+(x)+d+(y)+d-(u)+d-(v)≥2(n+p+q)-1,这里,x,y是任意控制顶点对,u,v是任意被控制顶点对;(3)D的弧数超过(n-1)2+q2+p;那么D是强(p,q)哈密尔顿的.     

GPS RAIM定位误差保护限值算法分析

针对基于最小二乘法的偏差完好性风险方法,采用总体最小二乘法估计准则,将数据矩阵和观测值两者的误差综合考虑,使残差更精确,数据可靠性更高,提高了RAIM算法的可靠性,并给出了RAIM解算模型.结合各个航段的完好性需求进行仿真,分析了不同飞行阶段的PIR性能.结果验证了PIR是更合适的可用性分析方法.     

Infrared image segmentation method based on 2D histogram shape modification and optimal objective function

In the methods of image thresholding segmentation,such methods based on two-dimensional(2D) histogram and optimal objective functions are important.However,when they are used for infrared image segmentation,they are weak in suppressing background noises and worse in segmenting targets with non-uniform gray level.The concept of 2D histogram shape modification is proposed,which is realized by target information prior restraint after enhancing target information using plateau histogram equalization.The formula of 2D minimum Renyi entropy is deduced for image segmentation,then the shape-modified 2D histogram is combined with four optimal objective functions(i.e.,maximum between-class variance,maximum entropy,maximum correlation and minimum Renyi entropy) respectively for the application of infrared image segmentation.Simultaneously,F-measure is introduced to evaluate the segmentation effects objectively.The experimental results show that F-measure is an effective evaluation index for image segmentation since its value is fully consistent with the subjective evaluation,and after 2D histogram shape modification,the methods of optimal objective functions can overcome their original forms’ deficiency and their segmentation effects are more or less improvements,where the best one is the maximum entropy method based on 2D histogram shape modification.     

Semi-algebraically connected components of minimum points of a polynomial function

In a recent article, the authors provided an effective algorithm for both computing the global infimum of f and deciding whether or not the infimum of f is attained, where f is a multivariate polynomial over the field R of real numbers. As a complement, the authors investigate the semi- algebraically connected components of minimum points of a polynomial function in this paper. For a given multivariate polynomial f over R, it is shown that the above-mentioned algorithm can find at least one point in each semi-algebraically connected component of minimum points of f whenever f has its global minimum.     

关于拟常曲率空间子流形的调和与Killing向量场

本文研究了一般拟常曲率空间N的紧可定向子流形M上的调和向量场,射影Killing向量场以及保形Killing向量场。给出了M上任意向量场所满足的两个积分公式,并且运用这两个积分公式讨论了M上的调和向量场、射影Killing向量场,保形Killing向量场的平行性、不存在性与M的主曲率之间的关系。同时在N为一种特殊的拟常曲率空间即S—流形的假设下又得出了进一步的结论。本文中主要结果是Shetty,D.J.在常曲率空间子流形上类似结果的推广。     

加权残数法在双曲扁壳有矩理论中的应用

文[1]讨论的加权残数法在正交正放类平板网架夹层板法中的应用,具有推导简单,內力挠度表达式简练易懂的优点。本文讨论的是将加权残数法由平板型结构推广到曲面壳体型结构的应用。工程界常用的壳体结构,以双曲率扁壳为多,但当跨度较大时,一般均采用符拉索夫(BπaCOB)的有矩理论[2]即建立两个高阶偏微分方程作为基本方程,通过单三角级数法或纳维尔(Navicy)双三角级数法求解出内力函数φ与法向位移ω。但是,单三角级数法求出的挠度、内力表式冗长,计算麻烦。纳维尔法所得的内力表达式虽然比较简单,但推导过程不如加权残数直接、简单。利用本文方法推导的双曲扁壳内力、挠度表达式与用纳维尔法所得结果完全吻合,说明其计算精度与收敛性均达到满意的结果。我们用本文的方法设计了18×18~M和36×37.5~M两个钢筋混凝土双曲扁壳结构,以证明其实用价值。     

高次抛物线的曲率与转角

本文讨论了高次抛物线曲率变化规律，指出了曲率取最大值的点处切线的斜率（转角）只与次数ｎ有关，且当ｎ→∞时，其极限为（３５．２６４°）。     

规范空间理论的破坏准则及经典形式

从脆性材料自身演变的角度，研究了各向异性材料破坏的内部规律和控制因素，提出了最小本征弹性趋近于零为各向异性材料在载荷作用下失效的破坏准则，并以最小本征弹性所对应的异性子空间中的模态应力达到临界值作为经典形式．在不变子空间情况下，在各向同性体及面上正好就是Ｍｉｓｅｓ强度准则     

几何形状对孤立导体面电荷分布的影响

本文通过例子说明了几何形状对孤立导体上面电荷分布的影响,然后再通过对几种带电孤立导体的电荷密度的分析、计算、讨论,得出孤立导体表面电荷分布不仅与导体表面的曲率有关,还与导体表面的整体形状有关。