Core experiments

Tubular conductors provide the most efficient system for current carrying, particularly large currents. As discussed above, the current density is the maximum at the skin (surface) of the conductor and falls rapidly towards the core. Experiments have been conducted to establish the normal pattern of current distribution in such conductors at different depths from the surface (Figure 31.11). 

Micic 01, Smith BB, Nozik AJ (2000) Core-shell quantum dots of lattice-matched ZnCdSe2 shells on InP cores Experiment and theory. J Phys Chem B 104 12149-12156... 

Hughes, J. C., Swain, T. (1962). After-cooking blackening in potatoes. II. Core experiments. J. Sci. Food Agric., 13,229-236. 

The core experiments with Kern River oil were performed using sandpacks (25.4 cm by 3.7 cm) made from unconsolidated field core. The core material was packed into Teflon sleeves with Teflon end caps and then placed into a Hassler type core holder. Before packing, the sand was cleaned by Soxhlet extraction with toluene and was not fired. Otherwise, the procedure was similar to that for saturating the consolidated Berea sandstone cores. 

The dissolved organic carbon concentration in uncontaminated ground water eluent for the Fe reduction core experiment was 120 mg/L C, and 0 mg/L C for the remediation experiments. 

Arsenic was modeled using a combination of adsorption on Fe(OH)3 and reductive dissolution of a separate, modified Fe(OH)3 sohd phase with a fixed concentration of As. Although Fe oxyhydroxide is represented as Fe(OH)3 in reaction 3, the actual formula for this solid phase in the geochemical model is Feo.995Aso.oo5(OH)3. This As/Fe ratio is based on results from the Fe reduction core experiment which is discussed later. 

Figure 3. Experimental and modeled As(IlI) concentrations (a) and Fe(II) concentrations (b) in leachate from the Fe reduction core experiment.

Arsenite concentrations in leachate from cores 1 and 2 are shown in Figs. 9a and 9b. Although 20% of the total As concentration measured in contaminated ground water samples collected in 1997 (Table 1) was determined to be As(V), all of the As in the core experiments was As(III). Arsenite concentrations in leachate from core 1 (initial pore water... 

The light exposure test matrix includes six core experiments. L-1 is a baseline experiment for the light exposure series it examines the effeets of photolysis reaetions on the exhaust composition. Experiment L-2 examines the effeet of HO reactions on exhaust composition at relatively high NOx. Experiment L-3 is proposed to examine the effect of the... 

Thompson and Gdanski (34) also performed dual-core experiments to determine the best diversion method using foam, and the maximum permeability difference needed to achieve an equal flow rate through the core. Multiple diversion techniques were used, including foamed acid, multiple stages of foamed add, and various qualities of foamed brine. The tests showed that foamed brine reduced flow rates better than foamed add. Also, higher quality foamed brines were most effective. In order to effectively use foamed diversion fluids, the permeabilities of the zones of interest must be relatively similar. The limit on permeability differences is approximately a factor of 10. Otherwise, the more permeable zone will accept both the diversion and treatment fluids. 

Langdon GS, Karagiozova D, von Klemperer CJ, Nurick GN, Ozinsky A, Pickering EG. The air-blast response of sandwich panels with composite face sheets and polymer foam cores experiments and predictions. Int J Impact Eng 2013 54 64-82. 

This demonstrates a significant improvement on the predictions made with the previous calculation scheme and data, in particular by calculating the values of the core experiments directly without the need for separate calculation and application of numerous additional corrections (e.g. the control rod worth calculation with the old scheme and data required some 50 basic calculations to reach the method biases necessary, while only 3 are needed with the new tools). 

Crystal core experiments have shown that trans-vinylene and diene are formed throughout the crystal with G values of 2.4 and 0.5 (100eV)" respectively. The trans-vinylene yield roughly agrees with the bulk yield, which appears to suggest a random process. 

A polyacrylamide and a polysaccharide (which performed best in the compatibility studies and in the core experiments) were tested for rheological and retentive behavior in the cores in a 100 percent brine environment. These tests were performed in order to examine the interaction of the pol3rmers with brines of unswept regions in the reservoir. The pol3nners were dissolved in distilled water and then mixed with 100 percent formation brine to the... 

In test tubes we had observed that, upon contacting an aqueous surfactant and polymer solution, a liquid-liquid phase separation can become visible after some time (2-40 hours). Such a phase separation could be harmful in field application, whereas it may either not show up or have only little effect in 0.3m core experiments, since these take only 24 hours. 

A critical experiment for nitride fuel FBR cores is in progress at Fast Critical Assembly (FCA) as a cooperative study between Japan Atomic Energy Research Institute and PNC. The first stage of the experiment, which consists of reaction rate and sample reactivity measurement in small area of nitride fuel, was completed on June 1994. The preliminary analysis showed the general prediction accuracy of the nitride fuel core seemed to be equivalent to that of the conventional oxide fuel cores. The second phase of the nitride fuel core experiment with enlarged region of nitride fuel is planned in 1996. 

Figure 18. Imbibition curves for the long water-wet and mixed-wet core experiments at low IFT. (Reproduced with permission from reference 97, copyright 1996 Elsevier.)...

At low IFT, oil production from a small mixed-wet core may stop even after just a small percentage recovery [97]. On the contrary, oil production would continue in a small water-wet core. In long core experiments, where the gravity forces are about 10 times larger than in small cores, the imbibition curves for mixed-wet and water-wet cores may be quite similar in shape. The production profiles have a break after a certain time, see Figure 18. This break is related to change in the imbibition mechanism. 

Apparatus. Essentially the coreflood equipment used for the long and short core experiments was very similar. For the short core experiments, only a single pressure drop across the whole core was measured. In the long core apparatus five separate pressure taps were mounted along the 1.8 m long core (see Figure 1). 

Foam Flooding in Oil Free Cores. Short Core Experiments. The bulk of the short core experiments consist of measurements of pressure drops and mobility reduction factors (MRFs) generated by foams in porous media. The MRF is determined by comparing the pressure drop across a core during simultaneous injection of surfactant solution and gas with that during injection of brine (without surfactant) and gas at the same experimental conditions. The MRF is defined as follows ... 

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