It was a valued export in Silk Road trading, but the manufacturing process was kept secret. During the Tang Dynasty (618-907) and the Song Dynasty (960-1279), varieties of paper were developed for different purposes.
April 7, 2015 Written by controlguru. Like the P-Only controller, the Proportional-Integral (PI) algorithm computes and transmits a controller output (CO) signal every sample time, T, to the final control element (e.g., valve, variable speed pump).
Traffic Control Devices â A sign, signal, marking, or other device used to regulate, warn, or guide traffic, placed on, over, or adjacent to a street, highway, pedestrian facility, or shared-use path by authority of a public agency having jurisdiction  Current TCD definition from MUTCD.