天顶距

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。

By the same method we also obtain the distribution of the lunar zenith distance versus the occurring probability of earthquakes.

同样的方法，可得地震的月球天顶距地震频度分布。

The difference between the observation atmospheric refraction and Pulkovo table is about 15 arc second at the zenith distance of 84 degree.

在天顶距84°时，与普尔科沃大气折射表的差值约为15。

The method does not depend on strict local parameters and precise instruments, while the observational principle is relatively simple. An experimental observation was carried out with a simple telescope with large field of view at Xinglong station of NAOC at the end of 2007. The atmospheric refraction from the zenith distance of 44.8 degree to 87.5 degree is gotten by the differential method, which proves the feasibility of the method tentatively.

该方法不依赖于严格的地方参数和复杂精密的观测仪器，并且观测原理相对简单。2007年底，利用一台简易的大视场望远镜在兴隆观测站进行了试验观测，根据较差方法实测得到真天顶距44.8°至87.5°的大气折射值，初步证明了大气折射较差测量方法的可行性。

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。

According to the engineering practice, the theoretical basis and method that survey directly the horizontal distance and height difference by the total station system as fourth grade and below fourth grade control network are put forward instead of surveying slant distance and zenith distance.

摘要根据工程实践，提出了用全站仪直接测量平距、高差来代替测斜距、天顶距作四等及四等以下控制网测量的理论依据和方法，并以张河湾抽水蓄能电站施工控制网为例进行了比较计算。

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。

Starting with the zenith, a series of star fields at different altitude are observed by a telescope with larger field of view, the derivatives of various orders are calculated at different zenith distances, and finally the observational atmospheric refraction can be obtained by numerical integration.

利用一台较大视场的望远镜从天顶开始，在不同高度上对星空作一系列观测，计算不同天顶距处大气折射函数的各阶导数，最后经数值积分可给出大气折射实测值。

Based on this, the characteristics of related celestial body positions at the occurrence time of the triggered earthquakes are studied. The distribution patterns, which have tidal_triggering physical basis, of lunar_solar ecliptic longitude differences and declinations and zenith distances are obtained.

在此基础上，对受到潮汐应力触发的地震发震时的天体位置特征进行了研究，得到了具有潮汐应力触发物理基础的地震时的月日黄经差、月日赤纬和月日天顶距的分布图像。

The patterns show that earthquakes in Yunnan are apt to be triggered by tidal stress during new moon and the first or third quarter of moon. The lunar_solar declinations at the occurrence time of the triggered earthquakes have banded dense distribution.

图像显示，云南地区的地震在新月期间和上下弦附近较易受到潮汐应力的触发；受到潮汐应力触发作用的地震发震时刻的月日赤纬有明显的密集分布条带特征，地震频次在月、日天顶距分别为30°～140°和20°～140°范围内为平均优势分布区间。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。