Sensor distribution

A water quality analyzer may be as simple as a probe inserted into the water and connected to a conveniently located recorder or as complex as a data collection system with multiple sensors distributed in several locations and provided with wired or wireless connection to a centralized data-com-piling system. Trace concentrations of components are monitored in drinking, industrial, and ultrapure water. 

Array stations are sets of 9-25 geometrically arranged seismic sensors distributed over an area of up to 500 km. These arrays have an enhanced detection capability and accurately measure the direction of the source of an event and its distance. 

Class of Sensors Distributed (D) or Centralized (C) Facility Potential Market ( million) Comments... 

The easiest way to locate the source of acoustic emissions is the so-called zone location method, where the exact source coordinates are not determined. Here, localization means detecting a signal and the radius (or in plate structures, the zone) of the sensor sensitivity range defines the localization accuracy. However, this is also the most imprecise localization method. The principal of zone localization is simple. For a particular sensor distribution, the sensor that records the arrival of the elastic wave first is the sensor closest to the source. An example for such a case is shown in Fig. 6.4. 

It is an important fact that for a homogeneous material the shape of the error ellipsoid is determined by geometrical relationships between source location and sensor distribution only, as summarized in the matrix G of the partial derivatives (Eq. 6.16 and 6.17). The data uncertainty is assumed to obey Gaussian statistics and acts as a scaling factor for C. 

Besides the reach discussed in section 16.2.2 the sensor distribution has a great influence for quantitative AE methods like source localization. 

The sensor distribution should be optimized for the expected source regions aiming at a good azimuthal coverage. 

For interpreting the results the uncertainties of the applied AE method have to be known. They are influenced by measurement errors like picking uncertainties, an inadequate sensor distribution, too less sensors or systematic model errors. Artificial sources with known parameters can be used for testing the accuracy of an AE method. 

As of 2011, pressure-measurement systems are stiU too expensive to allow sufficient numbers to be deployed to report pressure with enough spatial and time resolution to permit development of a real-time three-dimensional representation. Research in this area will doubtless improve the resolution and response and hopefully bring down the cost. With more pressure sensors distributed over the world, weather prediction will become more accurate and reliable. 

BIOTEX, an EU-funded project, aims at developing dedicated biochemical-sensing techniques compatible with integration into textiles. The goal was to monitor the body fluids via sensor distributed on a textile substrate and performing biochemical measurements. The approach involves the development of sensing patches adapted to different body fluids and biological species to be monitored, where the textile itself is the sensor (Coyle et al., 2010). 

Aromatic solvents or polycyclic aromatic hydrocarbons (PAFI) in water, e.g. can be detected by QCM coated with bulk-imprinted polymer layers. Flere, the interaction sites are not confined to the surface of the sensitive material but are distributed within the entire bulk leading to very appreciable sensor responses. Additionally, these materials show high selectivity aromatic solvents e.g. can be distinguished both by the number of methyl groups on the ring (toluene vs. xylene, etc.) and by their respective position. Selectivity factors in this case reach values of up to 100. 

Minimization of pollutants from the combustion chamber. This approach consists of designing the engine with improved fuel-air distribution systems, ignition timing, fuel-air ratios, coolant and mixture temperatures, and engine speeds for minimum emissions. The majority of automobiles sold in the United States now use an electronic sensor/control system to adjust these variables for maximum engine performance with minimum pollutant emissions. 

The balancing process must be in accord with the rotor dynamics, as specified by the operating environment. Unfortunately, the dynamic characteristics are often not properly recognized when the balancing procedure is specified. As a result, the unbalance distribution problem may not be identified not enough planes may be provided sensors may be located at nonoptimum positions, or critical speeds may be overlooked entirely. It is the responsibility of the machinery end user to satisfy himself that the manufacturer has considered ... 

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