Computer control information provided

The first set of case studies illustrates errors due to the inadequate design of the human-machine interface (HMI). The HMI is the boundary across which information is transmitted between the process and the plant worker. In the context of process control, the HMI may consist of analog displays such as chart records and dials, or modem video display unit (VDU) based control systems. Besides display elements, the HMI also includes controls such as buttons and switches, or devices such as trackballs in the case of computer controlled systems. The concept of the HMI can also be extended to include all means of conveying information to the worker, including the labeling of control equipment components and chemical containers. Further discussion regarding the HMI is provided in Chapter 2. This section contains examples of deficiencies in the display of process information, in various forms of labeling, and the use of inappropriate instrumentation scales. 

TTie detailed information provided by the measurement of mercury is vital to the economic operation of the plant, so it is necessary to hnk the measurements directly into the process control computer. This is achieved in a simple manner by adding a digital-to-analogue converter to the control computer. Once the analytical result is calculated for any run, the result can be transferred directly by the D/A converter to the process control computer in a 0—20 mA signal. 

A large part of accounting is concerned with providing control information for manufacturing operations. It is not within the scope of this chapter to discuss the many applications of computers in this work. There is, however, a part of accounting procedures which is of particular interest from a technical viewpoint. This is the subject of operations accounting, which is concerned with the current operations of process equipment. The subject is important in the planning of future operations as well as the control of current operations. It is worth while, if not indeed necessary, to know both what information is available and how it was obtained. 

Electronics for controlling instrument-operating parameters, such as temperature and pressure, have contributed to more stable operation. This produces better repeatability of the system for multiple cycles leading to higher precision of component isolation. Advantage of improved measurement devices can be realized once the sample preparation function is resolved. Computer hardware and software provide expanded capability for signal processing and data manipulation. Stable and precise sample preparation and measurement systems allow accurate analytical information provided that adequate maintenance and calibration practices are applied,... 

The undelayed evaluation of state of a culture by using software sensors and computers, based on the quantitative analytical information provided by hardware sensors and intelligent analytical subsystems, constitutes an excellent basis for targeted process control. Experts - either human or computer - have the data and the deterministic knowledge to trace observed behavior back to the physical, chemical and physiological roots thereby gaining a qualitative improvement of bioprocess control, a quantum leap process control can act on the causes of effects rather than just cure symptoms. A simple standard operating procedure [398] has proven useful, namely ... 

DEPT (Distortionless Enhanced Polarization Transfer) is a more recent technique that provides the same information as off-resonance decoupling. DEPT is easier to run on modem, computer-controlled Fourier transform spectrometers. DEPT gives better sensitivity, and it avoids overlapping multiplets because all the peaks remain decoupled singlets. 

This section should contain information on computer systems that control critical manufacturing processes. The developer of the system should be identified and information provided also should include a brief description of procedures for changes to the computer system. This section also should contain a validation summary for each of these systems and a certification that an IQ and OQ have been completed. 

Although not directly pertinent to detectors, the computer that handles the output from the detector should also provide other information in the analytical report. Today, most chromatographic systems, gas and liquid, have a dedicated computer associated with them which, as well as processing the information provided by the detector, will also control and record the operating conditions of the chromatograph. Temperatures, flow rates programs, etc., will be entered via the keyboard of the computer and the information stored for reporting purposes when required. 

Automatic specimen introduction requires the development of mechanical interfaces between each laboratory analyzer and devices such as conveyor belts, mobile robots, or robot arms. Enhancements to electronic interfaces for laboratory instruments are necessary to allow remote computer control of front-panel functions, notification of instrument status information, and coordination of the distribution of specimens between instruments. Most existing LIS interfaces with laboratory analyzers provide only the ability to download accession numbers and the tests requested on each specimen, and to upload the results generated by the analyzer. 

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