描述了基于以太网的无源光网络系统的框架结构、设计原则和网络规划；

The frame structures, design principles and network planning of system based on Ethernet Passive Optical Network (EPON) are described.

youdao

以广东省始兴县城区为例，运用景观生态学原理，探讨了城镇绿地系统规划的目标、原则、方法及布局结构等问题。

Taking Shixing County as an example, the goal, the principle, the methods, and the layout of the urban green system planning are studied by using the theory of landscape ecology.

youdao

阐述了污水收集系统的规划原则和本区管网布置特点。

The planning principles of the sewage collection system and the characteristics of sewer network layout are also introduced.

youdao