天顶

As one of the most often used mountings, the altazimuth mounting satellite tracker has a blind area near the zenith because of the very high azimuth angular velocity, as a result, discontinuous observing data are caused. As for those fast flying satellites, this kind of blind area is very significant because it causes difficulties in precisely determining the satellites' orbits.

作为最常用的一种机架，采用地平式机架的人卫跟踪仪在观测天顶附近区域的目标时，由于方位转速过大而不能连续观测，存在一个固有的天顶盲区，特别是对飞行速度较快的近地卫星，这个盲区的影响是相当大的。

You'll also need a diagonal and if this is your first apochromatic refractor, I'll recommend a 3-6 nagler zoom.

如果这是你的第一架复消色差折射望远镜，那么你还需要一个天顶镜。我推荐用3－6毫米耐格勒变焦的天顶镜。

The basic principle is based on spherical astronomy and elementary geometry of the trajectory mapping method based on the observation of a celestial body zenith distance, then the ship is located in order to sing the next point as the center of this satellite zenith distance of the ship's position as the radius of the circle, observing the same two objects, or objects at different times of the two observations, we can get two ship's position round, then the ship must have been a point of intersection of two ship's position on the circle.

其基本原理是建立在球面天文学和初等几何中的轨迹作图法基础上的，观测一个天体的天顶距，则航船就位于以星下点为圆心，此星天顶距为半径的船位圆上，观测两个天体或者不同时间同一天体的两个观测值，就可以得到两个船位圆，则航船一定在两个船位圆的一个交点上。

In order to improve the monitoring precision and resolution of tropospheric zenith delay, the hybrid approach, using a batch least squares estimator but parameterizing the zenith delay by a linear spline with knots at 30-minute intervals and treating the knots as a Gauss-Markov process, is employed to deal with the tropospheric zenith delay.

为了提高对流层天顶延迟的监测精度和分辨率，我们采用了分段的参数估计和随机过程相结合的估算方法来处理对流层延迟，由此获得了分辨率分别为2 h和30 min，精度好于1 cm的天顶延迟量。

The results indicate that the distribution of the solar zenith distance versus the occurring probability of earthquakes is quite consistent with the lunar case, and the case for small earthquakes is different from the larger earthquakes. The latter is mainly clustered at 0oand l80o of the zenith distance, and consistent with the distribution of the absolute value of the solar tide forces, while the former are clustered at 60o and l2Oo.

统计发现：地震的太阳天顶距地震频度和月球天顶距地震频度分布表现出一致的规律性，且较大地震和小地震的活动规律不同，较大地震丛集发生在太阳天顶距0°和180°附近，与地面引潮力的绝对值分布有较好的一致性；而小地震多丛集在太阳天顶距60°和120°附近。

Based on the ISC earthquake catalogue data, according to the orbit equations of two-body-problem and the perturbation theory of celestial mechanics, we could determine the projection pole of the sun, and thus calculate the zenith distance from the sun to the epicenter. After calculating all the earthquakes on their zenith distances, we could get the distribution of the solar zenith distance versus the occurring probability of earthquakes.

基于ISC地震记录，利用天体动力学中二体问题的轨道方程和摄动理论，确定发震时刻太阳在地面的投影点位置，并进一步计算出太阳相对震中的地心天顶距，将地震按天顶距的大小进行统计，得到地震的太阳天顶距地震频度分布。

Zenith telescope天顶仪It felt as if we had traveled from nadir to zenith.

感觉上我们好像已从天底走到了天顶。

The corona type aurora mainly occurs at polarward and overhead of Zhongshan Station during postnoon and around midnight. The band type aurora mainly appears during postnoon, while during evening and around midnight only appears at equatorward.

冕状极光主要出现在子夜附近和午后的极向侧和天顶，在傍晚出现很少；带状极光主要出现在午后和赤道侧的傍晚与子夜；极光浪涌主要出现在子夜前后；向日极光弧则主要出现在子夜前后，子夜前比子夜后多，极向和天顶比赤道侧多。

The conclusion is that the extent of the zenith blind zone was restricted by three parameters: maximum azimuth angular velocity of tracking mount, flight level and airspeed of the target. In astronomical coordinates (reference mark is north latitude 43. 9°), analyzed is the effect of azimuth angular velocity, acceleration and altitude angular velocity, acceleration etc. Some formulae were given to compute all correlative quantities.

在观测坐标系中推导出确定天顶盲区理论范围公式和满足过天顶跟踪条件的关系式；在天文坐标系中以长春卫星观测站（北纬43.9°）作为计算基准，分别讨论了方位、俯仰方向的角速度、角加速度等对天顶盲区的影响，在理论分析上为解决过天顶跟踪问题打下了基础。

The conclusion is that the extent of the zenith blind zone was restricted by three parameters: maximum azimuth angular velocity of tracking mount, flight level and airspeed of the target. In astronomical coordinates (reference mark is north latitude 43.9 ), analyzed is the effect of azimuth angular velocity, acceleration and altitude angular velocity, acceleration etc. Some formulae were given to compute all correlative quantities.

在观测坐标系中推导出确定天顶盲区理论范围公式和满足过天项跟踪条件的关系式；在天文坐标系中以长春卫星观测站(北纬43.9°)作为计算基准，分别讨论了方位、俯仰方向的角速度、角加速度等对天顶盲区的影响，在理论分析上为解决过天顶跟踪问题打下了基础。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。