What is CDN
The full name of CDN is Content Delivery Network. The purpose is to publish the content of the website to the "edge" of the network closest to the user by adding a new network architecture to the existing Internet, thereby increasing the speed of network access. Figure 1 is a CDN network hierarchy diagram. Common content distribution methods include configuring content server nodes at major Internet access points throughout the world (Figure 2), and using a special routing mechanism to redirect content requests to the closest content server. For example, when a web user clicks on a URL that can distribute content, the content distribution network redirects user requests to the nearest user based on information such as network traffic and connections, load conditions, distance to the user, and response time. The content server greatly improves the network access speed.
At present, CDN technology has achieved vigorous development. In China, CDN application services have been started, but the tracking and research of CDN technology is still in its infancy. The National "863" Fund has established a project for CDN, and the Institute of Communication and Information System of Zhejiang University has applied for the project and established a CDN laboratory. The initial research work has already begun. CDN routing is an important direction in the early days.
Incremental Encoder is commonly used, and Absolute Encoder is used if there are strict requirements on position and zero position. Servo system should be analyzed in detail, depending on the application situation. Commonly used incremental encoder for speed measurement, which can be used for infinite accumulation measurement; Absolute encoder is used for position measurement, and the position is unique (single or multiple turns). Finally, it depends on the application situation and the purpose and requirements to be realized.
Incremental Linear Encoders,Linear Optical Encoder,Linear Position Encoder,Encoder Bearing Tester
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