为了演示深度防御的工作原理，我们将首先研究包含三个主要层次的中心模型：核心层、中间层和最外层。
To show how the defense in depth works, we will first examine a centric model of three primary layers: core, middle, and outermost.
利用这一模型，研究了腐蚀速率、缺陷深度、管道壁厚和工作压力等因素对管线可靠性的影响。
The effects of corrosion rate, defect depth, thickness of pipe and operation pressure on pipeline reliability were investigated with this model.
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