Vertical electrical resistivity

Vertical Electrical Resistivity Sounding. The first example illustrates the ability of VES techniques to characterize regional subsurface geology into resistivity layers that have similar resistivity values at similar depths. Sediment lithologies and groundwater quality characteristics were determined for each unit based on observed resistivity values. The survey was conducted in Northampton County, Virginia which is located at the south end of the Del-Mar-Va Peninsula (9) (Figure 11). 

An improved approach from the point of view of thermal efficiency is the electrothermal process in which the mixture of zinc oxide and carbon, in the form of briquettes, are heated in a vertical shaft furnace using the electrical resistance of the briquettes to allow for internal electrical heating. The zinc vapour and CO(g) which are evolved are passed tluough a separate condenser, the carbon monoxide being subsequently oxidized in air. 

A mixture of powdered poly(vinyl chloride), cyclohexanone as solvent, silica, and water is extruded and rolled in a calender into a profiled separator material. The solvent is extracted by hot water, which is evaporated in an oven, and a semiflexible, microporous sheet of very high porosity ( 70 percent) is formed [19]. Further developments up to the 75 percent porosity have been reported [85,86], but these materials suffer increasingly from brittleness. The high porosity results in excellent values for acid displacement and electrical resistance. For profiles, the usual vertical or diagonal ribs on the positive side, and as an option low ribs on the negative side, are available [86],... 

Where RW of basic good quality is supplied for LP steam boilers (that is, firebox, Scotch marine, cast-iron sectional boilers, etc. at operating pressures below 15 psig) and where the MU water volume demand exceeds 5% of the FW, pretreatment by ion-exchange softening should be additionally provided. This rule also applies to electrical resistance boilers, electrode boilers, vertical boilers, and coil boilers. 

The idea of electronic conductivity in the crystals of this cluster is stimulated by the metallic reflectance of the crystals. A potential conductivity is expected to be anisotropic because of the anisotropic order of the clusters inside the crystal. As a consequence, the electric resistance is expected to be smaller in the direction of the tubes than in the vertical direction where there is no graphite-like bridging between the clusters. 

Fig. 1.22.3. Average of 22 electrical resistance plots of 1% NaCl solution (1 °C/min cooling) from -10 to -70 °C. Solid line, cooling vertical bars, average + sd. Dashed line, warming vertical bars, average + sd...

An electrical resistance heater with more turns at the tube ends (to compensate for heat losses) surrounds each tube. There is a vertical laminar flow hood over the loading area to minimize particle contamination of the wafers being loaded. As we can see, there are temperature controls for the furnace tubes, and a power module to provide the electrical power. When operated as a LPCVD system, a unit including both the gas flow and vacuum systems is positioned on the right side. Such a unit is shown in Figure 8. Here we can see the vacuum pumps on the left, and the mass flow controllers on the right. The vacuum pump oil recirculation systems are shown in the slide out drawers. As can be seen in Figure 9, this system, as well as most current similar systems, operate under computer control. 

To heat the materials under investigation to the required temperature and to maintain it, the electric-resistance furnace 1 is employed. The specimen 2 of a solid substance is connected, by means of the protective tube 3, with the shaft 5, being rotated by the electric motor 4. The shaft is free to move in the vertical direction and can be fixed in the required position by the stopper 6. The temperature is measured with the help of the thermocouple 7. The flux 8 is used both to pre-heat the solid specimen to the experimental temperature and to protect the liquid 9 from oxidation by atmospheric air. 

The electrical resistivity is as high as 1016 Q cm [17]. This is good for electrical isolation as it has been used for SOS (silicon on sapphire), but inhibits vertical current flow through sapphire. 

Electric resistance weld pipe is made from strip in coil form. After being uncoiled, flat strip is progressively rounded as it passes through a series of vertical and horizontal forming rolls before welding. Small-diameter pipe is welded by the high frequency induction method and medium-diameter... 

The salinity of formation waters is often calculated using electrical-resistivity and spontaneous-potential (SP) logs, and the values obtained are reasonable, except in geopressured zones with high shale content (Hearst and Nelson, 1985 Rider, 1996). It is often possible to determine vertical variations in salinity over a distance of several kilometers from a single log. 

The resistance distance is based on electrical network theory and is defined as the effective electrical resistance between two vertices (nodes) when a battery is connected across them and each graph edge is considered as a resistor taking a value of 1 ohm. 

For any pair of non-adjacent vertices, the resistance distance is the effective resistance calculated according to the two classical Kirchhoff laws for series and parallel electrical circuits some examples of calculations are given in Box R-1 for ethylbenzene. 

In a pioneering investigation, Serizawa [127, 128] measured the lateral void distribution as well as the turbulent axial liquid velocity fluctuations for bubbly air/water up-flows in a vertical pipe of diameter 60 (mm) inner diameter. They used electrical resistivity probes to measure the local void fraction, the bubble impaction rate, the bubble velocity and its spectrum. Turbulence quantities, such as the liquid phase mean velocity, and the axial turbulent fluctuations were measured using a hotfilm anemometer. A supplementary... 

Field surveys are conducted to complete either lateral profiles or vertical electrical soundings (VES). Resistivity profiles are completed by utilizing a fixed electrode spacing and obtaining an electrical resistivity value at each selected station along the... 

Data analysis and interpretation of electrical resistivity data may be limited because (1) resistivity values may be associated with any one of several geologic units (i.e. a silty sand unit may have similar resistivity values as a sand unit saturated with salt water) (2) thin beds of lower resistivity will be masked when they are sandwiched between two layers of higher resistivity and (3) the interpreted layer thickness will be greater than the actual thickness due to the anisotropic nature of the individual layers, which are generally characterized as having greater vertical resistivity values than horizontal (9). 

Figure 3.18 Change in electrical resistance of an anion exchange membrane (strongly basic anion exchange) with and without anionic polyelectrolyte layers in the presence of sodium tetradecyl sulfate (STS). 1. without the layers and with STS 2. with the layers (immersion time 4 h) and with STS 3. with the layers (immersion time 24 h) and with STS 4. with the layers and without STS 1 left vertical axis 2,3 and 4 right vertical axis. After an anion exchange membrane had been immersed in 100ppm anionic polyelectrolyte (polycondensation product of sodium naphthalene sulfonate and formaldehyde MW ca. 1000) solution for the respective time at room temperature, electrodialysis was carried out at a current density of 2.5 mAcmr2 using 0.10 N sodium chloride solution containing 2.16 X 10 3 mol dm3 of STS.

Fig. 2 Some of the very collinear sensor signals. The points in time where the value ofy( t) changed are marked by the vertical lines. The. sensor signals are electric resistances.

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