PID

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PID

PID

(1) (Process IDentifier) A temporary number assigned by the operating system to a process or service.

(2) (Proportional-Integral-Derivative) The most common control methodology in process control. It is a continuous feedback loop that keeps the process flowing normally by taking corrective action whenever there is any deviation from the desired value ("setpoint") of the process variable (rate of flow, temperature, voltage, etc.). An "error" occurs when an operator manually changes the setpoint or when an event (valve opened, closed, etc.) or a disturbance changes the load, thus causing a change in the process variable.

The PID controller receives signals from sensors and computes corrective action to the actuators from a computation based on the error (proportional), the sum of all previous errors (integral) and the rate of change of the error (derivative). See PAC.


Inputs from a PID
The large white boxes are Opto 22 SNAP PACs, which are programmable automation controllers that are processing the PID loops in Chevron's research facility in Richmond, Virginia. The wires come from thermocouples that sense pipe temperature in a laboratory test that analyzes the best way to break down crude oil. The PACs determine when to raise and lower the temperature, and the three modules with the black sockets send digital signals to the heaters (cables not connected in this image). (Image courtesy of Opto 22, www.opto22.com)
References in periodicals archive ?
The treatment in primary immunodeficiency: As a result of disrupted immune system function, frequent and multiple infections, autoimmune disorders and malignancies are commonly seen in patients with PIDs. Untreated or under-treated PID can lead to life-threatening infections, chronic organ damage, or a marked reduction in life expectancy (6).
Unlike the PCC, the PIDS acknowledged the 'technical loophole' that PLDT and Globe used to proceed with transaction while avoiding the antitrust body's scrutiny.
According to the UNHRC, most of the 8,745 PIDs are in Sarangani (3,155), while 2,777 are in Davao del Sur.
Actually, PIDs received P660 million - P560 million of the amount intended for the implementation of Grants-in-Aid for Research Development and Extension, and the remaining P100 million for the purchase of land and construct a building that would house the agency.
Increased aeration on lung graphy was found with a markedly higher rate in the patients with selective IgA deficiency compared to the other PIDs (44.4%).
The CISF, meanwhile, justified its action by saying that the PIDS system had malfunctioned.
Recipients were asked to complete the survey or forward it to other PIDs in their organization as appropriate.
Installation of the AgilFence PIDS at Changi has already begun, with the implementation to be rolled out in stages and the project to be completed by the end of 2012.
Pids chairman John Godfrey said: "The Pids board set its initial objective to collect only enough to repay the Defra loan.
Contributions of PID to other fields of medicine: Winkelstein concluded his seminars to nurses by identifying some of the significant therapies developed over the years as a direct result of research con ducted for the benefit of patients with PIDs.
PIDS noted emerging technologies such as 3D printing enables textile firms to improve their productivity and output at lower cost and fewer errors.