To query by distance, you must use a projected coordinate system. 要按照距离进行查询,必须使用投影坐标系。
The rectilinear ( straight-line ) coordinates of a projected coordinate system are distance measures, expressed in units of length. 投影坐标系的直线坐标是距离度量,表示为长度单位。
If any of these assumptions are not valid for your database, you have to make adjustments that vary from trivial ( for column names ) to somewhat involved ( in the case of a projected coordinate system ). 如果这些假设对于您的数据库不成立,那么必须做某些调整,这些调整可能很简单(比如对于列名),也可能比较复杂(比如对于投影坐标系)。
The aerodynamics and the propulsion are linearized with the coefficient freezing method, and projected in the airframe coordinate system. After simplified, the mathematical model is built, which is decoupled into the pitch / yaw model and the roll model. 基于系数冻结假设,线性化飞行器所受气动力和推力,投影在弹体坐标系中,经简化后得到控制系统线性数学模型,而后基于数据模型分析结论将该模型分解为俯仰偏航模型以及滚转模型。