协方差

Based on probability theory, a method for describing and calculating the collision probability between rendezvous and docking vehicle and debris is presented, and the method involves quantitatively analyzing the collision probability using quasi maximum instantaneous collision probability and total collision probability. The method calculating the indexes is developed, and the input required to perform a calculation includes the respective state vectors, position error covariance matrices and physical sizes of objects involved.(3) Two methods to analyze relative trajectory safety between chaser and target are developed, which are 3-sigma ellipsoid based methodology and collision probability based methodology.

1分析了交会对接各阶段面临的主要轨迹安全威胁，阐述了被动和主动安全策略、目标器的交会对接控制区域等保证交会安全的措施；(2)基于概率思想发展了线性和非线性运动情况下飞行器与空间碎片的碰撞判断方法，提出采用总碰撞概率和拟最大瞬时碰撞概率来综合描述飞行器与空间碎片的碰撞危险程度，推导了通过飞行器和空间碎片各自的状态矢量、位置误差协方差矩阵以及形状尺寸来计算碰撞概率的公式；(3)提出了两种分析追踪器和目标器之间相对轨迹安全的新方法：基于3σ椭球的轨迹安全分析方法和基于碰撞概率的轨迹安全分析方法。

To some extent,expectations and covariances can.

均值和协方差一定程度上可以描述这些随机变量的概率分布特性。

We use the normalized covariances between the first and theith protein to measure how the statistical correlations between them.

我们用标准化协方差来测量两个蛋白质之间的统计相关性。

In order to compute the optimal weights, the formulas of computing the local estimation error covariances are presented.

为了计算最优加权，提出了计算局部估计误差协方差公式。

Moreover,it involved less parameters and smoothed out differences in estimates of the covariances.

降阶配合涉及的参数较少，同时可以缓和协方差估值间的差异。

Results of both theoretical analysis and calculation examples show that these algorithms are effective, and the accuracy of algorithms relies on the expectation of nodal voltage and computation accuracy of covariances.

理论分析和算例结果表明了这些算法的有效性，算法的精确性依赖于节点电压的均值和协方差的计算精度。

The proposed method requires no a priori estimates of noise covariances, provides consistent estimates.

所提的方法不要求噪声协方差的先验估计，提供一致的估计。

The Lyapunov equations of computing local filtering error covariances are presented, which are applied to obtain the optimal weighting coefficients.

提出了计算局部滤波误差间的互协方差的Lyapunov方程，可用于计算最优加权系数。

NMC method is widely used to statistically analyze background error covariances currently.

NMC方法是目前较广泛采用的一种对模式背景场误差协方差进行统计分析的一种方法。

First, corresponding to the unknown virtual control coefficients and unknown noise covariances, some parameters to be estimated are properly chosen.

摘要研究了一类具有未知虚拟控制系数和未知噪声协方差的随机非线性时滞大系统的适应镇定问题。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了