sight reduction

简明释义

测天计算

英英释义

例句

1.After taking the measurements, the crew performed sight reduction to plot their course.

在进行测量后，船员进行了视线修正以绘制他们的航线。

2.The instructor demonstrated how to carry out sight reduction using a sextant.

讲师演示了如何使用六分仪进行视线修正。

3.Understanding sight reduction is essential for anyone studying maritime navigation.

理解视线修正对于任何学习海洋导航的人来说都是必不可少的。

4.In celestial navigation, sight reduction helps convert angles into usable coordinates.

在天文导航中，视线修正有助于将角度转换为可用坐标。

5.The process of sight reduction is crucial for navigators to determine their position accurately.

对于导航员来说，视线修正的过程对于准确确定他们的位置至关重要。

作文

In the field of navigation, particularly in celestial navigation, the term sight reduction refers to the process of converting the observations of celestial bodies into usable navigational data. This process is crucial for sailors and aviators who rely on celestial bodies like the sun, moon, stars, and planets to determine their position on the Earth. The importance of sight reduction cannot be overstated, as it allows navigators to accurately plot their course, ensuring safe travel across vast oceans and skies.To begin with, sight reduction involves taking accurate measurements of the angles between a celestial body and the horizon using a sextant or similar instrument. Once these measurements are obtained, the navigator must then perform calculations to convert these angular measurements into a geographic position. This typically involves using mathematical formulas and tables, such as the Nautical Almanac, which provides the necessary data about celestial bodies at any given time.The first step in sight reduction is to take a sighting of a celestial body. For instance, if a navigator sights the sun at a specific time, they record the angle of elevation above the horizon. This angle is known as the altitude. Along with the time of the observation, this data is essential for the next steps. The navigator also needs to account for various corrections, such as the height of the observer's eye above sea level and atmospheric refraction, which can affect the accuracy of the readings.After collecting the necessary data, the next phase of sight reduction involves plotting the information on a celestial navigation chart. This is where the navigator uses the calculated altitude and the time of the sighting to find the corresponding position of the celestial body on the chart. By doing so, they can draw a line of position (LOP), which indicates their possible location on the Earth’s surface.One of the challenges of sight reduction is that it requires a good understanding of both mathematics and astronomy. Navigators must be proficient in spherical trigonometry, as the Earth is a sphere and the calculations often involve spherical geometry. Additionally, they need to stay updated on the positions of celestial bodies, which change over time due to the movement of the Earth and other celestial phenomena.Moreover, technology has advanced significantly, and while traditional sight reduction techniques are still taught, many navigators now use electronic devices that automate much of the process. However, understanding the fundamentals of sight reduction remains essential, especially in situations where electronic systems may fail or when navigating in remote areas where technology is unavailable.In conclusion, sight reduction is a vital skill for anyone engaged in celestial navigation. It combines observational skills with mathematical prowess to enable navigators to determine their positions accurately. As we continue to advance in technology, the principles behind sight reduction remain relevant, serving as the foundation for modern navigation practices. Understanding and mastering this process ensures that navigators can safely and effectively traverse the world's oceans and skies, relying on the stars and celestial bodies that have guided explorers for centuries.

在导航领域，尤其是天文导航中，术语sight reduction指的是将天体观测结果转换为可用导航数据的过程。这个过程对于依赖太阳、月亮、星星和行星等天体来确定地球上位置的水手和飞行员至关重要。sight reduction的重要性不容小觑，因为它使导航员能够准确地绘制航线，确保安全地穿越广阔的海洋和天空。首先，sight reduction涉及使用六分仪或类似仪器测量天体与地平线之间的角度。一旦获得这些测量值，导航员必须进行计算，以将这些角度测量转换为地理位置。这通常涉及使用数学公式和表格，例如《航海年鉴》，该年鉴提供了任何给定时间天体的必要数据。在sight reduction的第一步中，导航员需要观察天体。例如，如果导航员在特定时间观察到太阳，他们会记录太阳在地平线上方的高度角。这个角度被称为高度（altitude）。连同观测时间，这些数据对于下一步至关重要。导航员还需要考虑各种修正因素，例如观察者眼睛高于海平面的高度和大气折射，这些因素可能影响读数的准确性。在收集到必要的数据后，sight reduction的下一阶段涉及在天文导航图上绘制信息。这时，导航员使用计算出的高度和观测时间来找到天体在图表上的相应位置。通过这样做，他们可以绘制出一个位置线（LOP），表示他们在地球表面可能的位置。sight reduction的挑战之一在于它需要对数学和天文学有很好的理解。导航员必须精通球面三角学，因为地球是一个球体，计算通常涉及球面几何。此外，他们需要随时了解天体的位置，天体位置会随着时间的推移而变化，这是由于地球的运动和其他天文现象造成的。此外，科技已经显著进步，尽管传统的sight reduction技术仍然被教授，但许多导航员现在使用电子设备来自动化处理过程。然而，理解sight reduction的基本原理仍然至关重要，特别是在电子系统可能失效的情况下，或者在技术无法使用的偏远地区进行导航时。总之，sight reduction是从事天文导航的任何人都必须掌握的重要技能。它结合了观察技能和数学能力，使导航员能够准确确定自己的位置。随着我们继续在技术上取得进展，sight reduction背后的原则仍然具有相关性，作为现代导航实践的基础。理解和掌握这个过程确保导航员能够安全有效地穿越世界的海洋和天空，依靠那些几个世纪以来引导探险家的星星和天体。