3 thoughts on “What is DDC?”

  1. DDC refers to Dewey's decimal classification method.
    Dewey decimal (DDC) is a classification method widely used in libraries around the world. This classification system was first published in 1873, Melvil Dewey, and was officially published in 1876, named "AND SUBJECT Index for And Arranging The Books and Pamphlets of a Library."
    The relevant information:

    DDC has been used by libraries in more than 135 countries around the world, and more than 30 languages ​​are translated, including Arabic, Chinese, French, Greek, Hebrew , Italian, Persian, Russian, Spanish and Turkish text. In the United States, 95%of public libraries and school libraries, 25%of colleges and university libraries and 20%of special libraries use DDC. In addition, DDC can be used to organize various resources on the Internet.
    DDC is classified by traditional disciplines. A total of 10 main disciplines (Main Classes) include all the knowledge systems. Each category is subdivided by 10 categories, and then divided into 10 small small categories. Class (Sections).

  2. Control for short), the computer collects real -time data through analog input channel (AI) and switch quantity input channel (DI), then calculates in accordance with certain rules, and finally sends out control signals. The quantitative output channel (DO) directly controls the production process. Therefore, the DDC system is a closed -loop control system and is the most common application method in the process of industrial production. The computer in the DDC system undertakes the control task directly, so it requires good real -time, high reliability and adaptability.

  3. Direct digital control system (Direct Digital Control short), the computer collects real -time data through analog input channel (AI) and switch volume input channel (DI), then calculates in accordance with certain rules, finally sends out control signals, and uses analog quantity through the simulation quantity quantity Output channel (AO) and switching output channel (DO) directly control the production process. Therefore, the DDC system is a closed -loop control system and is the most common application method in the process of industrial production. The computer in the DDC system undertakes the control task directly, so it requires good real -time, high reliability and adaptability.

Leave a Comment