基于单位四元数的单独像对相对定向

目前对单位四元数描述空间旋转的应用,基本上是将其转换成旋转矩阵的形式,而忽略了单位四元数描述空间向量旋转具有描述几何关系的直观性以及运算简洁的优势。基于此提出一种基于单位四元数的单独像对相对定向法,方法首先采用向量描述同名光线,然后利用单位四元数描述立体像对中左右影像同名光线的变换关系,建立单位四元数共面条件方程模型,再按照带有约束条件的间接平差原理进行最小二乘平差,确定相对定向元素。针对RC30航空影像和低空无人机影像采用单位四元数法分别进行单独像对相对定向实验,结果表明单位四元数相对定向方法计算精度较高,为解决摄影测量中坐标变换问题提供更多选择。     

Hannay angles for relativistic polar orbits around an oblate spheroid

The Hannay adiabatic angles are computed for polar orbits in the gravitational field of an oblate spheroid described in the post-Newtonian framework of general relativity.     

Comparison of the dynamic response of a saturated soil between two models

The dynamic response of marine sediment to ocean surface waves is treated extremely by marine geotechnical and coastal engineers. In the area of conventional hydrodynamics, the assumption of im-permeable rigid seabed has been used as the boundary of water waves theories and the waves parameters de-duced from the theory have not referred to the interac-tion of water waves and seabed. In the area of soil mechanics, many engineers regard the response as slow loading according to the Zienkewiczs[1…     

测角观测误差在初轨确定中的传布

本文用非线性规划方法探讨了初轨确定问题。测角观测误差看作为参数的微摄动,而非线性规划的灵敏性分析模型（ｆｈｐ） 建立在无摄动的情况下。由此,得出了在一阶近似下轨道根数计算值和测角观测误差值间关系的分析表达式。     

线阵CCD指向角解算方法的模拟实验研究

本文根据卫星线阵CCD指向角的特点提出简化解算模型,用单位四元数来描述旋转角,以几乎无偏估计作为平差方法。通过一系列模拟实验证实在外方位元素初值比较准确的前提下可以以较高精度求得设计的参数。模拟了不同的姿态稳定度、控制点精度、控制点密度、岭参数及航线长度对解算结果的影响。     

等高线光滑中不合理尖角钝化方法研究

在等高线光滑过程中,会出现一些不合理的尖角,影响制图效果,本文提出一种钝化尖角的方法,使经过钝化处理后的等高线更加光滑、制图效果更好。试验表明此方法在钝化尖角的过程中,既能够保持等高线的基本形状,又能够钝化尖角,满足生产要求,具有推广使用的价值。     

带双腹板顶底角钢连接初始刚度研究

初始连接刚度在节点刚度分类和钢结构地震分析中占有很重要的地位,因此研究连接的初始刚度很有现实意义。主要研究带双腹板顶底角钢连接初始刚度的确定方法以及影响其性能的主要因素。     

Studies of TLP dynamic response under wind, waves and current

Investigated is the coupled response of a tension leg platform (TLP) for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load of TLP in moving coordinating system. Infinitesimal method is applied to divide columns and pontoons into small parts. Time domain motion equation is solved by Runge-Kutta integration scheme. Jonswap spectrum is simulated in the random wave, current is simulated by linear interpolation, and NPD spectrum is applied as wind spectrum. The Monte Carlo method is used to simulate random waves and fluctuated wind. Coupling dynamic response, change of tendon tension and riser tension in different sea conditions are analyzed by power spectral density (PSD). The influence of approach angle on dynamic response of TLP and tendon tension is compared.     

坡面日出日没时角的配置关系与太阳赤纬

若坡面的坡向β和纬度φ满足条件| sinβcosφ|≥sin 23°26',则坡面日出日没时角的配置关系不随太阳赤纬的变化而变化;反之,则存在两个绝对值相等、符号相反的一般临界赤纬δc,以-δc、δc为界,坡面日出日没时角的配置关系具有三种不同的形式。坡面日出日没时角的配置关系及其随太阳赤纬的变化,可根据δ=δc时,非水平面日出日没时角和水平面日出日没时角的相等关系、坡向、坡度确定。在水平面或非水平面极昼、极夜前后,坡面日出日没时角的配置关系也会发生变化。     

Active region magnetic fields

The tilt angles of sunspot groups are defined, using the Mount Wilson data set. It is shown that groups with tilt angles greater than or less than the average value (≈ 5 deg) show different latitude dependences. This effect is also seen in synoptic magnetic field data defining plages. The fraction of the total sunspot group area that is found in the leading spots is discussed as a parameter that can be useful in studying the dynamics of sunspot groups. This parameter is larger for low tilt angles, and small for extreme tilt angles in either direction. The daily variations of sunspot group tilt angles are discussed. The result that sunspot tilt angles tend to rotate toward the average value is reviewed. It is suggested that at some depth, perhaps 50 Mm, there is a flow relative to the surface that results from a rotation rate faster than the surface rate by about 60 m/sec and a meridional drift that is slower than the surface rate by about 5 m/sec. This results in a slanted relative flow at that depth that is in the direction of the average tilt angle and may be responsible for the tendency for sunspot groups (and plages) to rotate their magnetic axes in the direction of the average tilt angle.