Sensitivity filters

By choosing the proper correlation algorithm, it is possible to realise sensitive filters for other types of defects (e.g. corrosion). Fig. 5.2 shows an example for the suppression of signals which do not exhibit the expected defect stmcture (Two parallel white lines near upper central rim portion of Fig. 5.2). The largest improvement in SNR is obtained here by using the expression (ai ai+x /ai+yj), since for a gradiometric excitation, one expects the crack response to show two maxima (a, aj+x) with a minimum (a m) in the centre (see Fig. 5.3). 

Microstructured surfaces, as well as micromachined substrates and devices discussed in Sects. II, III, and iy are suitable for a number of applications. They include reflective and absorbing surfaces, wavelength-sensitive filters, multiaperture lens arrays and Fresnel microoptics, field emitter arrays, precision apertures, or molds for microstructured surfaces of other materials. Microstructured alumina ceramics can also be used for tuned broadband infrared emitters. In addition, due to the robustness at high temperatures and well-developed and controlled porosity, the freestanding, heat-treated micromachined anodic alumina substrates can be used for the fabrication of sensors that incorporate a high temperature microheater with low power consumption. 

An accurate and convenient configuration for measuring luminous efficiency from OLEDs/PLEDs is shown in Fig. 4.5. Because the luminous efficiency strongly depends on the OLED/PLED emission spectrum (even for constant quantum efficiency), an eye-sensitivity filter is mounted directly onto the surface of the calibrated photodiode (see Fig. 4.4) [15],... 

The direct determination of amino acids using ion-exchange analysers. Any standard amino-acid analyser may be modified by the addition of a sensitive filter fluorimeter to allow the determination of amino acids down to a few picomoles. The reagent employed, o-phthalaldehyde, is best prepared as given in section 2.1.3 and mixed 1 1 with the column effluent, allowing 2 min reaction time at room temperature before passing the reacted stream through the fluorimeter cell. 

In Section 11.3, various wavelength-sensitive filter types were discussed, including cut-off and bandpass filters. The response of those filters was related to internal material properties (e.g. coloured glasses). The same filter effects, i.e. sharp cut-off or very narrow band-pass, can be achieved by using tailor-made... 

For an industrial application it is necessary to separate the response of a real crack from artifacts, and to derive information about the geometry and the location of the crack. For this purpose we have developed a filter which is sensitive to the characteristic features of a signal caused by a crack and amplifies it, whereas signals without these typical features are suppressed. In Fig. 5.1 first results obtained with such an iterative filter algorithm are shown. 

The image generated by the image intensifier was found to be very sensitive to noise and to reduce this effect, a low pass filter was included. This filter has greatly improved the final 3D... 

The oxidation of black lead(II) sulphide to the white sulphate is a very sensitive test if the black sulphide is used as a stain on filter paper. 

Both these acids are colourless, but the spots of each acid on a filter-paper strip show up in ultraviolet light as intense blue fluorescent zones. They can also be detected, but considerably less sensitively, by spraying with ethanolic ferric chloride solution, which gives with N-methylanthranilic acid a purple-brown coloration. 

It is advisable to test a small portion of the filtrate for platinum by acidifying with hydrochloric acid and adding a few drops of stannous chloride solution a yellow or brown colour develops according to the quantity of platinum pVesent. The yellow colour is soluble in ether, thus rendering the t t more sensitive. If platinum is found, treat the filtrate with excess of formaldehyde and sodium iQrdroxide solution and heat,- platinum black septarates on standing and may be filtered and worked up with other platinum residues (see Method 3). 

Photomultipliers are used to measure the intensity of the scattered light. The output is compared to that of a second photocell located in the light trap which measures the intensity of the incident beam. In this way the ratio [J q is measured directly with built-in compensation for any variations in the source. When filters are used for measuring depolarization, their effect on the sensitivity of the photomultiplier and its output must also be considered. Instrument calibration can be accomplished using well-characterized polymer solutions, dispersions of colloidal silica, or opalescent glass as standards. 

Dewatering of high value products and particle systems sensitive to high pressure drops are the most likely candidates for electrofiltration. The Dorr-OHver Electrofilter is a commercial example of a vacuum filter adapted for electrofiltration. 

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