Reliable sensor system

Many other important application areas of chemometrics have been the subject of reviews and are too numerous to list here. A sampling of reviews in this category illustrates the breadth and diversity of chemometrics application areas. A review of applications in smart sensors [54] describes how chemometrics is an important enabling technology for the development of smart and reliable sensor systems. A review of environmental forensics [55] describes how numerical methods are critical in the process of identifying the chemical fingerprints of complex contaminant sources in environmental systems. Often, multiple sources are present at different geographic sites. By use of appropriate chemometric methods, these mixtures of different sources can be mathematically resolved to identify them and map their temporal and spatial distributions. 

Robots will become an essential component of Integrated automated manufacturing systems In the future The development of a reliable sensor system for detecting the Intrusion of humans Into robotic work areas will greatly Improve the safety conditions Many types of systems are possible candidates, but the capacitive system Is the most promising one at the present time ... 

Reliable gas sensor systems that are small and inexpensive and do not need re-calibration over a lifespan of at least 10 years are required for... 

In the past few decades, a precise methodology has been developed for sensory evaluation and has proved to give reliable results [826]. Increasingly, in recent years chemical sensor systems ( electronic noses ) are used for such purposes [826a]. 

A very simple type of a bubble column, which was not mentioned above is a gas-wash bottle. This very small-scale system (VL = 0.2-1.0 L) may be used for basic studies, in which general effects (e. g. influence of pH and/or buffer solutions specific ozone dose) are to be assessed. Its use is not recommended for detailed studies, because the mass-transfer coefficient is often low and its dependency on the gas flow rate is unknown or difficult to measure. Often there is no possibility to insert sensors or establish a reliable measuring system for exact balancing of the ozone consumption. An optimal mode of operation would comprise treatment of the (waste-)water for a certain period of time, preferably without withdrawal of solution during the ozonation. In this way different ozonation conditions can be tested by varying the ozonation time or the ozone gas concentration. A variation of the gas flow rate is not recommended. 

Although new techniques of analyzing VOCs like sensor systems and online mass spectrometers have been introduced in the last decade, the use of solid sorbents in combination with thermal desorption and gas chromatographic separation still seems to be the preferred method due to the sensitivity, selectivity, convenience of use and the reliability that has been proven over the years. 

If it is possible to get highly reliable devices to process thousands of samples immediately with an appropriate production technology to obtain cheap and portable devices, a breakthrough of microanalytical sensor systems is still to be expected. 

The integrated system, including transducer and enzyme reactor, provides improved reliability and stability in multianalyte determinations, as compared with discrete thermal sensor systems. In addition, application of micromachining and IC technologies is of benefit for the manufacture of uniform, cheap thermal transducers with flexible shape, size, and resistance, as well as delicate microstructure on the chips. The good thermal insulation of the transducers from the flow stream eliminates interference from the reactants on the transducers, and the intrinsic stability of the transducers obviates the need for frequent recalibration of the sensors. 

The vision of braking and steering by wire will demand new, extremely reliable sensors. Even in early implementations of steer-by-wire systems, in which manual control can override any system failure, more than one sensor is normally used for the sake of redundancy. Many of the sensor principles required are already established in the market, including steering-angle sensors (e.g., for vehicle dynamics control) and pedal-position sensors. Mechanical action or feedback control, however, will drive the emergence of torque and force sensors. 

Sensors for force and torque measurement in automotive applications will always reflect the needs of the system in which they are used. For reasons of cost and reliability, most system designers try to reduce the number of sensors. 

A perfect sensor is defined by the point in the upper left of the ROC curve. The red line shows behavior typically observed when the analyte concentration lies below the detection limit of a sensor system. In this instance, attempts to increase sensitivity by amplifying the signal provide a yes/no detection answer near that of a random guess line. The intermediate blue curve displays typical behavior when analyte concentration approaches the useful range for a sensor. Increasing the sensitivity so that an analyte is reliably detected (increasing TPP) will also increase... 

Micromachined and microfabricated electrochemical sensors have been used either per se, or as part of a sensor system, in many practical applications. This includes various biosensors and chemical sensors reported in research literature. An example of a practical electrochemical sensor is the yttria-stabilized zirconium dioxide potentiometric oxygen sensor used for fuel-air control in the automotive industry. Thick-film metallization is used in the manufacture of this sensor. Even though the sensor is not microsize, this solid electrolyte oxygen sensor has proven to be reliable in a relatively hostile environment. It is reasonable to anticipate that a smaller sensor based on the same potentiometric or the voltammetric principle can be developed using advanced microfabrication and micromachining techniques. 

Systems such as the one illustrated in figure 23.2 will also incorporate artificial intelligence. The information from the sensors will be used with fuzzy logic and neural networking to enable decisions by individual controllers based on the input from multiple sensors. Such systems will also incorporate sensor self-testing, self-calibration, and fault correction, resulting in reliable, automated systems applicable to any process or production line. These systems will significantly affect the productivity and profitability of food, chemical, and pharmaceutical production. 

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