四元数

A novel direction of arrival and polarization estimation of electromagnetic vector sensors mounted on the airframe is proposed based on biquaternion. The signal processing model for EM-sensor mounted on the airframe is made by biquaternion and then the eigenvalue decomposition of spectral matrix is obtained by means of the EVD of its quaternion adjoint matrix. The memory requirement for data is reduced, and more accurate estimation result is gotten by deducing the stronger orthogonality constraint between the sin- gal and noise subspaces on the field of biquaternion. The performance of the new algorithm is confirmed through numerical examples.

针对机载电磁矢量传感器阵列DOA和极化参数估计问题，提出了一种基于复四元数估计方法，该算法利用四元数建立机载电磁矢量传感器阵列信号处理模型，然后利用四元数联合矩阵的特征分解得到阵列数据相关矩阵的特征分解，一方面使得计算过程中数据的贮存量大大减少，另一方面通过推导得到信号子空间和噪声子空间在四元数域上的正交性从而使DOA和极化参数佑计的精度更高，仿真证实了本算法的有效性。

The research on the CCD sensor information is used to determinate the satellite attitude system without gyroscope .(1) Using quaternion and MRP as attitude representation , the attitude kinematics function are established . The satellite attitude dynamics function is established,that is disturbed by the first-order Markov force moment.(2) Using the quaternion as attitude representations, the attitude determination state estimator EKF and UKF are designed , numerical simulation is done .

基于CCD星敏感器的无陀螺测量卫星姿态确定系统的研究(1)针对地球同步轨道卫星，分别建立了以姿态四元数和修正罗德里格参数为卫星姿态描述参数的姿态运动方程；建立了卫星受一阶马尔柯夫干扰力矩时的卫星姿态动力学方程；(2)设计了采用姿态四元数为卫星姿态描述参数的EKF和UKF估计器，设计了分别以姿态四元数和修正罗德里格参数为卫星姿态描述参数的UKF估计器，并进行了数学仿真。

The quaternion calculation for spacecraft attitude determination is investigated in this paper,including the transformation between quaternion and the direction cosine matrix,the quaternion differential equation,the selection of time steps for integrating the quaternion equation,and the compensation methods for the noncommutativity error in high dynamic motion.

介绍了四元数计算中的相关问题，包括四元数与方向余弦阵之间的转换、四元数运动方程、求解四元数运动方程时积分步长的选取和高动态应用中非互易误差的补偿，此外还介绍了对偶四元数的发展。

The research of matrixes is continuously an important aspect of the quaternion division algebra. The purpose of this paper is to discuss the property of skew self-conjugate matrix. The definition of skew self-conjugate matrix on real quaternion division algebra is given.

四元数体上矩阵的研究是四元数代数理论中的一个重要方面，本文研究实四元数体上斜自共轭矩阵的性质，给出实四元数体上斜自共轭矩阵的定义。

Rotation, store the data in the matrix as an axis/angle and do the conversions yourself or will need to convert it to a quaternion.A quaternion is composed of four components: a vector with x, y, z coordinates and a w rotation.

当用一个四元数乘以一个向量时，实际上就是让该向量围绕着这个四元数所描述的旋转轴，转动这个四元数所描述的角度而得到的向量。

Furthermore, we express a real quaternionic polynomial with four general polynomials which have real coefficients, thus build direct relation between real quaternionic polynomials and general polynomials.

新方法以四元数的复表示及其可对角化的特征结构为理论基础，将问题等价为求解2×2矩阵多项式的可对角化解；进一步将四元数多项式用四个实系数多项式表示，建立了四元数多项式与一般多项式的直接关联。

The reason why quaternion is used in flight simulation of fighter aircraft and the geometric meaning of quaternion are described,according to axis system used in flight simulation of fighter aircraft in China,three problems are introduced as follows:(1) quaternion kinematic equations,(2) relationship of quaternion and coordinate transformation matrix,(3) Euler angles in terms of quaternion.

阐述了在战斗机的飞行仿真中采用四元数的原因和四元数的几何意义，并按照中国战斗机飞行仿真中采用的坐标系，介绍了三个问题：四元数运动学方程；四元数与坐标变换矩阵的关系；用四元数表示的欧拉角。

The numerical calculations of quaternion matrices The quaternionic quantum mechanics is a new coming disciplines of physics, because of noncommutation of quaternions, some numerical calculation methods of quaternion and quaterinon matrices are complicated and tedious.

四元数矩阵的数值计算问题四元数量子力学是近十几年来才发展起来的一门新兴的物理学科，由于四元数乘法的不可交换性，使得四元数量子力学中的四元数数学理论基础，特别是有关四元数问题的数值计算方法很不完备。

By comparing the matrix theory over number field,we mainly discussed the quaternion matrix norm theory,the quaternionic determinant,the complex number expression of the quaternion matrix and the quarternion linear matrix equation.

通过对比一般域上矩阵理论，本文主要从四元数矩阵范数理论、四元数矩阵行列式、四元数矩阵的复表示以及四元数线性方程组和线性矩阵方程四个方面阐述了四元数矩阵理论。

In the last two chapters, this thesis first develops two quaternion-based color image filtering methods that are based on the quaternion rotation theory and quaternion unit transform, respectively, then analyzes the fulfillment algorithm of the QSVD (Quaternion Singular Value Decomposition) and its applications to color image processing, and expands the real number-valued PCA to quaternion-valued PCA.

在论文的最后二章，通过利用四元数旋转和色调抵消机制以及四元数单位变换来表达二个彩色像素的色调差异，提出了二个基于四元数理论的彩色图像滤波的新方法；并分析了四元数奇异值分解QSVD (Quaternion Singular Value Decomposition)的实现算法及其在彩色图像处理中的应用；同时将实数域上的主成份分析扩展到四元数域，形成了四元数版本的主成份分析QPCA (Quaternion Principal Component Analysis)。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。