Saturated Cores

The core is put into a Hassler sleeve inside a core holder where overburden pressure is applied outside of the sleeve by using water. Gas is not used, since it has the potential to diffuse through the rubber sleeve. The overburdened core holder is connected to the Isco pump, from which 1% acidified brine is pumped into the core. The needle valve that restricts flow from the output end of the core is opened slightly to allow the escape of air and air-saturated brine. The needle valve which restricts flow from the input end of the core is opened fully. Complete saturation is attained after several pore volumes of brine have been pumped through the core under pressure, and this fully saturated core is used throughout the experiment. 

Other important characteristics of the converter are the reflected ripple attenuation and the turn-on characteristics. It is expected that the turn-on characteristics will be difficult to simulate because of the nonlinear characteristics of a saturating core. A nonsaturating core is simply described by Faraday s law, and it can be easily modeled by any of the SPICE simulators. The model used for the EMI filter is shown in Fig. 3.66, and the results of each of the simulators output and the measured impedance plots are shown in Figs. 3.67 to 3.70. 

Note the saturating core model is available in both PSpice and IsSpice. In PSpice the core is available as part of the AEi Systems Power IC Model Library for PSpice. This figure is shown to give a visual representation of the effects of an EMI filter. 

Thordarson (1) and Benson (LBL, Berkeley, written commun., 1978) both describe the Paintbrush Tuff as partially saturated. Core samples obtained from the lower part of the Paintbrush in the tunnel complex were reported by Diment and others (2 ) to have saturation levels of 55-91 percent, with an average of 77 percent. Benson (LBL, Berkeley, written commun., 1978) reported an average value for water saturation in the Paintbrush of 90 percent. It would therefore be expected that the total aquifer-pore surface would not be involved in transport of water. As a matter of fact, assuming that all of the saturated-pore space is effective in transmitting water, one might predict that, on the average, somewhere between 77 and 90 percent of the aquifer surface is in contact with percolating water. 

A core-flood for adsorption determination consists of injecting a measured volume of surfactant solution containing a nonadsorbing tracer into a brine-saturated core and collecting effluent fractions at the core outlet. Chemical analysis of the effluent samples allows the calculation of an adsorption level based on material balance considerations and also results in a set of effluent profiles for the surfactant and the tracer. In addition to the material balance, adsorption is evaluated by matching experimental effluent concentrations from the core-floods with a convection—dispersion—adsorption numerical model. The model parameters then allow calculation of a complete adsorption isotherm. 

A 14-electron tt system can be generated in circumstances in which the steric problem associated with the internal hydrogens of [14]annulene can be avoided. This can be achieved in 10b,10c-dihydropyrene systems, in which the annulene ring is built around a saturated core. 

Research on liquid crystals with a disc-like shape started in 1977 [130] when hexa(hep-tanoyl)benzene (38, first synthesized forty years earlier [131]) was proved to form a columnar mesophase (m.p.=/tj, 81.2°C, cl.p.=/ci 87.0°C) [132]. Disc-shaped amphiphilic molecules with saturated cores, such as the hexaesters 39 or even the hexa-ethers 40 of the naturally occurring scyllo-inositol [9, 109, 133-137] form columnar liquid crystals much more easily with me-sophases more stable and very much wider in range than known for the mentioned benzene derivatives. 

SCR Abbreviation for either saturable-core reactor or sihcon-controlled rectifier. 

The pore volume (later referred to as PV or t) and the porosity, ( ) of the dry packed core is first determined from the weight and measured grain density of the Ottawa sand (2.65 g/cc) and the bulk volume of the core. The permeability of the sandpack to gas is then measured in a N2 permeameter from a minimum of six values of pressure drop versus flowrate. The core is placed in a multifluid flow displacement apparatus for saturation with brine or fresh water. The saturated core is oil flooded to irreducible water saturation, at rates which make the capillary pressure... 

Production, concentration and pressure histories of secondary waterflood and tertiary sodium hydroxide flood of brine saturated core. 

The untreated cores were saturated with brine, whereas the Dri-Film treated cores were saturated with Soltrol in a core saturator. The saturated cores were weighed, and with the help of the known density of the liquid the porosities were calculated. 

The saturated core is placed in the core holder and its initial permeability (K ) of the sandstone core is then measured by pumping a 30,000 ppm of sodium chloride solution at a constant... 

LDL. The corresponding fragmented alkyl phosphatidylcholines, butanoyl GPC and butenyl GPC products are inflammatory platelet-activating factor (PAF)-like phospholipids and also named butanoyl PAF and butenyl PAF. These C-4 core aldehydes are probably the most stable and are readily analysed directly by LC-MS. Several additional and perhaps more bioactive unsaturated core aldehydes are also expected by non-enzymatic oxidation and fragmentation of PC and CE containing arachidonic, linoleic and n-3 PUFA acids (see Chapter 4) in oxidized LDL. These unsaturated core aldehydes may not have been detected because they may form covalent PC-apoprotein adducts that are not readily identified and analysed directly by LC-MS. However, these unsaturated core aldehydes may be potentially more bioactive and important than the saturated core aldehydes reported in oxidized LDL. 

Baseline pressure drops, APn, were measured during co-injection of brine and gas into a previously brine saturated core (no foam present in... 

An initially brine saturated core was flooded with oil to irreducible water saturation (S c), and subsequently waterflooded. During the water-flooding stage, the pressure drop and oil productions were continuously monitored until the residual oil saturation was reached. In Figure 27 the comparison between experimental and simulated values of the waterflood recovery and concurrent pressure drop (across the core) is made. The history matched relative permeability curves are shown in Figure 28 the corresponding parameters are listed here ... 

Figure 8, from reference [14], shows the permeability ratio as a function of the acid injection rate. For brine saturated cores, the final core permeability exponentially increases with the acid injection rate. The same trend is noted in the case of oil saturated cores. 

The cyclohexyldecalin material (compound 37) has a completely saturated core that may be expected to pack well in a lamellar fashion and indeed an SA phase is exhibited. However, the broad molecular structure reduces smectic phase stability and allows a large nematic range to be generated. When this broad core structure comprises saturated and aromatic regions (compound 38), the smectic phase is completely ehminated to give a nematogen of reduced phase stability. 

As the alternating current input of a transformer increases, the output also increases, but it reaches a maximum value when the core becomes "saturated" and can no longer increase its magnetization. If the transformer is purposely operated under these conditions, the output will be constant, even if the input varies a small amount. This is sometimes used to provide a dependable, constant voltage to operate sensitive instruments, heaters, and other devices, and it is called a "saturable core reactor" or a "constant voltage transformer." In newer equipment designs, it has mostly been replaced by the semiconductor devices that will be described in Chapter 15 (Fig. 15.6). 

The aluminium calorimeter block is maintained at a constant temperature within a cylindrical furnace which has main and control heaters parallel to, and end heaters perpendicular to, the cylindrical axis of the furnace. Power input is via a saturable core reactor operating from a resistance bridge. 

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