Computer-based instrumentation

However, the developments of microprocessor or computer-based instrumentation that can be used to monitor the operating condition of plant equipment, machinery and systems have provided the means to manage the maintenance operation. They have provided the means to reduce or eliminate unnecessary repairs, prevent catastrophic machine failures, and reduce the negative impact of the maintenance operation on the profitability of manufacturing and production plants. 

Calculation If a computer-based instrument is used, the data output is reported as micrograms per liter. Calculate the concentration of arsenic, in micrograms per gram (equivalent to milligrams per kilogram), in the original sample taken by the formula... 

Today the tunneling microscope is a member of a whole new class of computer-based instruments (SPMs) employing scanning proximity probes combined with feedback systems to control the probe s vertical position relative to its lateral position on the sample under investigation. Conceptually and operationally they are elegantly simple and versatile. Features common to all proximity microscopes are the use of (1) very fine sharp tips, (2) small. 

Number bias is another source of personal systematic error that is widely encountered and varies considerably from person to person. The most common bias encountered in estimating the position of a needle on a scale is a preference for the digits 0 and 5. Also prevalent is a preference for small digits over large and even ones over odd. Digital displays and computer-based instruments eliminate number bias. 

At the outset it was clear that the development of a computer-based instrument and the use of a surrogate compound (tracer) would make the method much more complex than the traditional approach. Thus, the study has extended over several years, involving both laboratory and field tests. Appropriate fluorescent tracers were first screened, and their chemical and environmental characteristics studied. Simultaneously, the video image processing system was designed and tested. Software was then developed to run the system, and evaluation and quantification procedures established. Finally, the system was taken into the field to study applicators conducting routine spraying operations. 

With current technology, it is possible in principle to develop computer based instrumentation and control systems with the necessary dependabihty for systems important to safety and to demonstrate their safety sufficiently. However,... 

Many modern instruments use computers and computer monitors as readout devices. Data manipulation, data processing, and formatting for graphical display and printing can all be done with the computer. Computer-based instruments arc discussed in detail in Section 4D. 

Monitoring and control of the production process will be performed by a combination of instrumentation and control equipment plus manual involvement. The level of sophistication of the systems can vary considerably. For example, monitoring well performance can be done in a simple fashion by sending a man to write down and report the tubing head pressures of producing wells on a daily basis, or at the other extreme by using computer assisted operations (CAO) which uses a remote computer-based system to control production on a well by well basis with no physical presence at the wellhead. 

Energy Spectrometry (EDS) uses the photoelectric absorption of the X ray in a semiconductor crystal (silicon or germanium), with proportional conversion of the X-ray energy into charge through inelastic scattering of the photoelectron. The quantity of charge is measured by a sophisticated electronic circuit linked with a computer-based multichannel analyzer to collect the data. The EDS instrument is... 

The case study described here concerns a human factors audit of a computer controlled process system which was being introduced in a distillation imit of a chemical plant. The unit was in transition from replacing its pneumatic panel instrumentation with the new system. However, control had not yet been transferred and the staff were still using the panel instrumentation. The role of the project was to evaluate a preliminary design of the computer-based display system and provide recommendations for future development. 

Fraunhofer rules do not include the influence of refraction, reflection, polarization and other optical effects. Early Iziser particle analyzers used Fraunhofer approximations because the computers of that time could not handle the storage cuid memory requirements of the Mie method. For example, it has been found that the Fraunhofer-based instrumentation cannot be used to measure the particle size of a suspension of lactose (R.I. = 1.533) in iso-octane (R.I. = 1.391) because the relative refractive index is 1.10, i.e.- 1.533/1.391. This is due to the fact that diffraction of light passing through the particles is nearly the same as that passing around the particles, creating a combined interference pattern which is not indicative of the true... 

Pressure or density programming is the most popular of the gradient techniques in SFC. Density is the important parameter with respect to retention but pressure is the physical property which is directly monitored by SFC instruments. If enough experimental density-volume-temperature data are available for the mobile phase then a computer-based algorithm can be used to generate specific density programs. Such data are available for only a few mobile phases, such as carbon dioxide and the n-... 

Although the condensation of phenol with formaldehyde has been known for more than 100 years, it is only recently that the reaction could be studied in detail. Recent developments in analytical instrumentation like GC, GPC, HPLC, IR spectroscopy and NMR spectroscopy have made it possible for the intermediates involved in such reactions to be characterized and determined (1.-6). In addition, high speed computers can now be used to simulate the complicated multi-component, multi-path kinetic schemes involved in phenol-formaldehyde reactions (6-27) and optimization routines can be used in conjunction with computer-based models for phenol-formaldehyde reactions to estimate, from experimental data, reaction rates for the various processes involved. The combined use of precise analytical data and of computer-based techniques to analyze such data has been very fruitful. 

---