Measurement Grid

Concerning some counted algae species, linear dimension measurements were performed, using a special measuring grid on the ocular of the microscope. 

Figure 6.18 Polymer pore surface characterizations (a) measurement grid from SEM and (b) plateau occurrence frequency distribution.

Rotameters have a glass tube with a flow element trapped between the measurement grid. This type of device provides direct contact between the measurement element and the fluid. Flow typically enters at the bottom of the rotameter and lifts the flow element. Oval gear meters and turbine flow meters displace a specific amount of liquid on each rotation. This is used to calculate total flow rate through the system. Pitot tubes are positioned perpendicular to flow. As the liquid enters the tube, precision-machined sensing vents determine flow rate. 

Twenty-seven capacitance wave gages were used to measure surface wave elevations (Fig. 39.12). The first four gages were located parallel to the wavemaker to measure incident wave conditions. The same procedure for locating the incident gages as described for previous experiments was followed. A measurement grid of... 

Positive ions are obtained from a sample by placing it in contact with the filament, which can be done by directing a gas or vapor over the hot filament but usually the sample is placed directly onto a cold filament, which is then inserted into the instrument and heated. The positive ions are accelerated from the filament by a negative electrode and then passed into a mass analyzer, where their m/z values are measured (Figure 7.1). The use of a suppressor grid in the ion source assembly reduces background ion effects to a very low level. Many types of mass analyzer could be used, but since very high resolutions are normally not needed and the masses involved are quite low, the mass analyzer can be a simple quadrupole. 

The room air concentration (Q) can be determined by measuring the concentration for a grid of points around the room. 

To produce this kind of grid map by quickly measuring the concentrations at some points for immediate processing and graphical presentation is a simple and often effective way to communicate the results to persons w ho are not trained to analyze primary results of measurements. The method must, however, be used with care since there is a risk that the sampling of data itself may affect the airflow in the studied area. I he equipment needed is relatively expensive, and the method is therefore of interest when the prerequisites are already available for other reasons. 

It is of course also possible to arrange so that the measurements are made at every point with a fixed instrument and the data transferred to a computer equipped with suitable software to produce the grid map, all in real time. If the graph is also superimposed on a video picture from the measured area, the result will be a video, visualizing the. spatial distribution in real time. 

Hot grid anemometer An instrument for the measurement of fluid velocity simi-... 

Pulsed hot wire anemometer A device used for gas flow measurement, similar to the hot grid anemometer, in which measurement, are made by pulses of hot air at a downstream sensor. 

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