Monitoring mixing

One chemometric method used to monitor mixing involves comparing the spectrum for the unknown sample with that for one assumed to be homogeneous via the so-called conformity index , which is calculated by projecting the spectrum for the unknown sample onto the wavelength space of the spectrum or mean of spectra for the homogeneous sample. This procedure is similar to that involving the calculation of distances in a principal component space. 

Y. Liu, D.O. Wipf and C.S. Henry, Conductivity detection for monitoring mixing reactions in microfluidic devices, Analyst, 126 (2001) 1248-1251. 

There is a need for improving the understanding of complex fluid and suspension flow behavior in mixing equipment. The concentration profiles obtained by MR imaging were used to monitor mixing with respect to axial position in a Kenics mixer, to which the two viscosity-matched test fluids were delivered at approximately the same volumetric flow rate. ... 

World Wide Monitoring Mixed-mode sorbents, drug analysis specialists... 

To conclude this chapter, we will present a brief introduction to some emerging technologies for monitoring mixed-phase flow. 

The principle of operation of the hydraulic reciprocating pump is similar to the beam pump, with a piston-like sub-surface pump action. The energy to drive the pump, however, is delivered through a hydraulic medium, the power fluid, commonly oil or water. The power fluid drives a downhole hydraulic motor which in turn drives the pump. A separate surface pump delivers the hydraulic power. The power fluid system can be of the closed loop or of the open type. In the latter case, the power fluids are mixed with the produced fluid stream. The performance of the hydraulic pump is primarily monitored by measuring the discharge pressures of both surface and sub-surface pumps. 

Instead of shifting the detector position, as indicated in figure B2.5.1 one often varies the location of the reactant mixing region using moveable injectors. This allows complex, possibly slow, but powerfril, analytical teclmiques to be used for monitoring gas-phase reactions. In combination with mass-spectrometric detection. 

Thermal energy in flame atomization is provided by the combustion of a fuel-oxidant mixture. Common fuels and oxidants and their normal temperature ranges are listed in Table 10.9. Of these, the air-acetylene and nitrous oxide-acetylene flames are used most frequently. Normally, the fuel and oxidant are mixed in an approximately stoichiometric ratio however, a fuel-rich mixture may be desirable for atoms that are easily oxidized. The most common design for the burner is the slot burner shown in Figure 10.38. This burner provides a long path length for monitoring absorbance and a stable flame. 

Suffice it to say at this stage that the surfaces of most solids subjected to such laser heating will be heated rapidly to very high temperatures and will vaporize as a mix of gas, molten droplets, and small particulate matter. For ICP/MS, it is then only necessary to sweep the ablated aerosol into the plasma flame using a flow of argon gas this is the basis of an ablation cell. It is usual to include a TV monitor and small camera to view the sample and to help direct the laser beam to where it is needed on the surface of the sample. 

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