Performance Evaluation of Color Face Hallucination with a Linear Regression Model in MPCA.

A dual speed hub includes a CPU, two hubs of different transmission speeds, two MACs (media access controls), and a switch, wherein the CPU periodically sends a test packet in proper order through one MAC, one hub, the switch and the other hub to the other MAC, then checks the receiving condition and the content of the returned test packet, then determines the normality of the function of the switch subject to the receiving condition and the content of the returned test packet, and then provides a warning signal to a network management system when the switch is judged abnormal, informing the network manager to repair the switch.