Interrogation Area

A problem occurring is the deviation of the reflected hue values at isothermal conditions which is caused by several factors (see section Measurement Accuracy ). To decrease the position-dependent errors like illumination or image acquisition, a local calibration can be done. Hereby the FOV is divided in interrogation areas, and a temperature-hue calibration curve is... 

PIV Particle Image Velocimetry To obtain the velocity field with the PIV method (see also Micro-PlV-Based Diffusometry), two images with a short time interval A< are applied. It is possible to use the same images for the estimation of the temperature and the velocity fields (see Fig. 6). Therefore intensity images are created of the RGB images, which are preprocessed as described above and divided into interrogation areas. The two-dimensional cross correlation of related interrogation areas leads to the pixel displacement in the... 

The resolvable spatial resolution of temperature measurements in liquids mainly depends on the concentration of the TLCs in the suspension, the size of the averaging area (interrogation area) and the size of the TLC particles. To decrease the size of the averaging area, a better hue response of the temperature of the TLCs is needed. Since the concentration of the encapsulated TLCs in the suspension is restricted by the signal-to-noise ratio, only a smaller diameter of the particles can improve the resolvable spatial resolution. 

PIV is used to estimate two-dimensional velocity fields of fluid flows. The fluid is seeded with tracer particles (able to follow the flow) whose motion gives information about the motion of the fluid. Therefore, two images taken at two times are divided into interrogation areas. 

The normal or spontaneons Raman spectra of neat recrystalhzed samples of PETN and SEMTEX are shown in Fig 1(a) and 1(b), respectively. SEMTEX samples were smeared over stainless steel plates as previously described. Figure 1(b) shows that the amount of SEMTEX in the field of view of the objective is so little that only one signal (1291 cm, NO2 symmetric stretch) is clearly detected by spontaneous Raman spectroscopy (which has a hmit of detection of several picograms, depending on the analyte). It is estimated that there were 15-30 picograms (pg) in the interrogation area, if it is assumed that the analyte was uniformly distributed on the metal surface. 

By combining the velocities of all interrogation areas, the instantaneous velocity profile is obtained. 

The volume average displacement of the particle images between the interrogation areas in the first and second images in PIV (m)... 

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