Infrastructure Layer - physical hardware, network and operating systems.

基础架构层——物理硬件、网络和操作系统。

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The whole system was divided into three layer: physical layer, communication link layer and application layer.

把整个系统分为三层：物理层，通信链路层和应用层。

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It features a simple interface and the physical key requirement provides an additional layer of security that avoids using a vendor's redirection service such as those offered by Cloud Engines for PogoPlug or Axentra for Netgear's Stora.

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To change your view layer in Apple Maps you have to tap the lower right corner (helpfully curled over as if it were physical paper) to reveal quite small traffic, satellite and hybrid views among four other options.

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