Principles of Systems Science by George E. Mobus & Michael C. Kalton

Author:George E. Mobus & Michael C. Kalton
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Communications subsystems allow intra-process coordination or cooperation. What is required is that two or more processes have established a channel link. As we saw before, a communications chan nel is of value when it most efficiently provides a mechanism for sending and receiving messages, as covered in Chap.7. Cooperation is possible when the communications are two way, meaning that one process can send messages to the other and vice versa, creating a feedback loop that enables them to work in terms of one another.

Processes can communicate, after a fashion, in a one-way message sent through whatever substance is being sent by one and received by the other (e.g., product from A to B). What is necessary is that the receiver must have some means to interpret the message and act on whatever information is contained. For example, process B in Fig. 9.1, above, can monitor the actual flow of a low entropy material that it receives from process A. Fluctuations in the flo w rate may encode information that will activate reactions by process B. Indeed most complex systems have subsystems that receive and monitor their input flows. A raw material inventory system in a manufacturer, for example, has to monitor the flows of received material in order to provide information on things like late deliveries.

But one-way communications can only suffice in purely reactive systems, those that may take action but are not, technically speaking, cooperating with their supplier. Two-way communications evolved as a way to allow complex processes to coordinate their activities. This figure shows a basic set up for two-way communications.

Internally, both processes need to have subsystems as covered in Chap. 7 that allow them to encode and receive/decode the messages. Each needs a transduction capability that includes a way to encode energy flows through the communications channel to the other (partner) process. Each also needs a way to interpret the incoming signal and actuate responses based on the information content.

Question Box 9.2

In what ways is this communication also a computation process, as discussed in Chap. 8?

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