Control chemical sensors

Chemical sensors are key in the transportation industry. Sensors are used to determine the fuel ratio, manage the optimum ratio, and measure the oil quality for pollution control. Chemical sensors monitor tailpipe emissions and catalytic converters. Additionally, sensors aid in chemical diagnostics of oil, transmission fluids, and other performance fluids. 

Many physio-chemical processes involve a time delay between the input and output. This delay may be due to the time required for a slow chemical sensor to respond, or for a fluid to travel down a pipe. A time delay is also called dead time or transport lag. In controller design, the output will not contain the most current information, and systems with dead time can be difficult to control. 

Miller H.H., Hirschfeld T.B., Fiber optic chemical sensors for industrial and process control, Proc. SPIE-Int. Soc. Opt. Eng. 1987 718 39. 

Sol-gel coating technique for optical chemical sensors and biosensors is now in extensive research phase. For example, the side-coating of optical fibers or waveguides in evanescent-wave sensors it is particularly important to control precisely the sensitivity determining parameters, such as the coating thickness and length45. 

Chemical sensors are widely used to monitor hazardous and combustible gases [65]. Applications include safety control in industrial applications, surveillance of boilers and other devices which are operated with natural gas as well as more sophisticated areas like cooking control and odor determination [66]. 

Fan, X. White, I. M. Zhu, H. Suter, J. D. Oveys, H., Overview of novel integrated optical ring resonator bio/chemical sensors, Proc. SPIE (Laser Resonators and Beam Control X) 2007, 6452, 64520M.1 64520M.20... 

Chemical sensors are becoming more and more important in any area where the measurement of concentrations of volatile compounds is relevant for both control and analytical purposes. They have also found many applications in sensor systems called electronic noses and tongues. 

In parallel with improvements in chemical sensor performance, analytical science has also seen tremendous advances in the development of compact, portable analytical instruments. For example, lab-on-a-chip (LOAC) devices enable complex bench processes (sampling, reagent addition, temperature control, analysis of reaction products) to be incorporated into a compact, device format that can provide reliable analytical information within a controlled internal environment. LOAC devices typically incorporate pumps, valves, micromachined flow manifolds, reagents, sampling system, electronics and data processing, and communications. Clearly, they are much more complex than the simple chemo-sensor described above. In fact, chemosensors can be incorporated into LOAC devices as a selective sensor, which enables the sensor to be contained within the protective internal environment. Figure 5... 

Biological chemical detection, chemical sensors versus, 22 269 Biological Control of Weeds Handbook,... 

S. M. Barnard and D. R. Walt, Chemical sensors based on controlled-release polymer systems,... 

Production of the API begins with the selection of a synthetic route, as determined in the development program. Raw materials are added into a reaction vessel. These raw materials as reactants are heated or cooled in the reaction vessel (normal range is from -15 to 140 °C purpose-built vessels are needed for extreme reactions that require lower or higher temperature controls or pressurization of reaction processes). The chemical synthesis reactions are monitored and controlled via sensor probes (pH, temperature, and pressure) with in-process feedback controls for adjustments and alarms when necessary. Samples are withdrawn at dehned intervals for analysis to determine the reaction progress. Catalysts, including enzymes, may be added to speed up and direct the reaction along a certain pathway. 

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