Tomographic technique

The presence of a magnetic dipole moment in many nuclei that have an intrinsic spin has found enormous application in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). NMR is extensively used in chemical laboratories to identify the structural and chemical environments of the nuclei in molecules, whereas MRI uses a tomographic technique to locate specific molecules... 

Many studies on the flow distribution in random packed beds have been reported in the literature. Mercandelli et al. [8] published a short review of the flow distribution work in random packed trickle bed, which includes the list of various techniques used to determine and quantify the flow distribution. Conventional methods include, for example, collecting liquid at the bottom of the column from different zones while advanced methods include tomographic techniques. Mercandelli et al. [8] used several techniques to quantify liquid distribution in columns of diameters up to 30 cm with three different distributor designs. They used global pressure drop measurements, global residence time distribution (RTD) of the liquid, local heat transfer probes, capacitance tomography and a collector at the bottom of the column. 

Examples of the use of tomographic techniques to determine gas/liquid distribution in stmctured packing is limited in the open literature. Mewes et al. [9] studied flow distribution in monoliths using capacitance tomography. A spatial... 

On the other hand, as only the global content in the sample is to be derived, imaging and tomographic techniques... 

T. Dyakowski, A.J. Jaworski, Application of tomographic techniques for imaging fluidized beds, 3rd Israeli Conference for Conveying and Handling of Particulate Solids, Dead Sea, Israel, 2000, pp. 15.1-15.10. 

The direct tomographic technique can be further subdivided according to the detector area into which a certain elemental volume in the object can radiate. For the case of a primary beam confined to a 1-D pencil beam, these include the point-to-point, point-to-line, line-to-line and point-to-plane variants [35],... 

Foods, in general, present online physical measurements with quite a challenge, in particular the need to obtain 100% inspection arising from the highly variable nature of the raw materials. Ultrasound is one technique, which has the potential for 100% inspection using tomographic techniques (Beck et al., 1994), in which the entire sample is penetrated by the inspecting field. 

Figure 4.20 The moving concentration waves corresponding to variations in the oxidation state of the IVln + Mn + cations during the BZ reaction in a cylindrical reactor. The pattern presents the time evolution of the concentration profiles along the reactor, which is observed using the NMR tomographic technique. The dark regions indicate a higher concentration of Mn +. A total of Mn concentration is 0.006 M [7].

Some, if not all, of the requirements of in-line measurement techniques are satisfied in tomographic techniques that provide spatially and temporally resolved data. The techniques utilize the inherent properties of the food material and include those based on magnetic, acoustic, optical, and electrical signals (Choi et al., 2002). These... 

Positron emission tomography (PET) is another tomographic technique using radiotracers, labeled with... 

Tomographic results. Upper-mantle velocity structure (James et al. 20016) was determined by tomographic techniques based on the analysis of delay times from teleseismic broadband waveform data. Relative arrival times of phases P, PKPdf, S and SKS were retrieved via a multichannel cross-correlation procedure using all possible pairs of waveforms (VanDecar Crosson 1990). This procedure produces highly accurate delay times, with typical standard errors for the... 

Interferometry, Holographic, and Tomographic Techniques for Scalar Measurements... 

Gas holdup can be measured by numerous invasive or noninvasive techniques, which have been reviewed by Kumar et al. (1997) and Boyer et al. (2002), and include changes in total bed expansion upon gassing, pressure drop measurements, dynamic gas disengagement (DGD), and tomographic techniques. 

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