Direct current voltage gradient

The effectiveness of cathodic protection can be accomphshed by monitoring the pipeline potential using the close interval potential survey (CIPS) method or by using direct current voltage gradient (DCVG) or IR coupon techniques. Also, physical and electrochemical methods can be used to estimate the corrosion rates of a cathodicaUy protected system. 

Direct and Alternating Current Voltage Gradient Surveys... 

Countercurrent electrophoresis can be nsed to split a mixtnre of mobile species into two fractions by the electrical analog of elntria-tion. In such countercurrent electrophoresis, sometimes termed an ion still, a flow of the suspending flnid is maintained parallel to the direction of the voltage gradient. Species which do not migrate fast enough in the applied electric field will be physically swept out of the apparatus. An apparatus based mainly on this principle bnt nsing also natural convection currents has been developed (Bier, Electrophoresis, vol. II, Academic, New York, 1967). 

The negative sign indicates that positive ions flow in the direction of the negative potential gradient. Note that the current density and current is the same at all positions across this cell, since the voltage gradient is linear across the cell (assuming that the conductivity is also the same at all positions). 

Figure 8 shows power output characteristics of FGM thermoelectric sample shown in Figure 7. Voltage-Current plot and Power-Current plot show the difference in the direction of temperature gradient applied to the sample. Output power with forward temperature gradient is 6% larger than that with reversed temperature gradient. The most likely explanation of this asymmetry can be found in a graded structure of the sample. But there is room for argument on this result because there seems a problem on reproducibility of both the material properties and the soldering technique. In this study the expected enhancement on conversion efficiency is rather small, it seems necessary to solve the problem mentioned above.

Electrophoresis is the transport of charged particles of colloidal size and bound contaminants due to the application of a low direct current or voltage gradient relative to the stationary pore fluid. Compared to ionic migration and electroosmosis, mass transport by electrophoresis is negligible in low-permeability soil systems. However, mass transport by electrophoresis may become significant in soil suspensicm systems, and it is the mechanism for the transportation of biocolloids (i.e., bacteria) and nucelles. 

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