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Effect of cation exchange on major cation chemistry in the large scale redox experiment at Aespoe

Description: Predicting the chemical changes that result from excavating a repository below the groundwater table in granitic terrain is a major focus of the SKB geochemistry program. The modeling study presented here demonstrates that cation exchange can play a major role in controlling the fluid chemistry that results when groundwaters of differing composition mix due to flow induced by excavation of the HRL tunnel. The major goal of this study was to assess whether an equilibrium cation exchange model could explain the composition of groundwater sampled from boreholes in the HRL tunnel. Given the consistency of the cation exchange hypothesis with observations, geochemical modeling was used to assess whether the quantity of exchanger necessary to match model results and observation was physically reasonable. The impact of mineral dissolution and precipitation on fluid chemistry was also evaluated. Finally, the compositions of exchanger phases expected to be in equilibrium with various Aespoe groundwaters were predicted.
Date: October 1, 1994
Creator: Viani, B.E. & Bruton, C.J.
Item Type: Article


Description: A series of experiments were performed to examine the effect of metal cations common to high level waste on the phase of aluminum formed. Experiments were performed at temperature of 150 C, 75 C, and room temperature, either without additional metal cation, or with 0.01-0.2 molar equivalents of either Ni{sup 2+}, Fe{sup 3+}, Mn{sup 2+}, or Cr{sup 3+}. Results showed that temperature has the greatest effect on the phase obtained. At 150 C, boehmite is the only phase obtained, independent of the presence of other metal cations, with only one exception where a small amount of gibbsite was also detected in the product when 0.2 equivalents of Ni{sup 2+} was present. At 75 C, a mixture of phases is obtained, most commonly including bayerite and gibbsite; however, boehmite is also formed under some conditions, including in the absence of additional metal ion. At room temperature, in the absence of additional metal ion, a mixture of bayerite and gibbsite is obtained. The addition of another metal cation suppresses the formation of gibbsite, with a couple of exceptions (0.2 equivalents of Ni{sup 2+} or 0.01 equivalents of Cr{sup 3+}) where both phases are still obtained.
Date: July 31, 2012
Creator: Taylor-Pashow, K. & Hobbs, D.
Item Type: Report

Effect of Ce composition on the structural and electronic characteristics of some metal hydride electrodes: A XANES and EXAFS investigation

Description: Substitution of the B component in the prototype AB{sub 5} type (LaNi{sub 5}) metal hydride alloys have resulted in their increased acceptance as anodes for rechargeable alkaline batteries. Recently substitution of the A component (La) for imparting properties such as increased corrosion resistance has received attention. This investigation deals with the role of Ce as a substituent for the La and its effect in terms of corrosion resistance. The alloys chosen have the general composition of La{sub x}Ce{sub 1-x}B{sub 5} (x = 1, 0.8, 0.5 and 0.25) where B is Ni{sub 3.55}CO{sub 0.75}Mn{sub 0.4}Al{sub 0.3} together with alloys containing the mischmetal (Mm) as the A component (both synthetic and commercial). Electrochemical cycling results show that Ce lowers the capacity loss in the alloys and that this effect is not a simple function of the extent of lattice expansion during hydriding as was previously suggested. Correlation of the electrochemical and XAS results show that capacity loss is directly related to the extent of Ni corrosion. Effect of Ce substitution seems to result in a stable Ce oxide hydroxide coating which imparts the corrosion resistance.
Date: December 31, 1994
Creator: Mukerjee, S.; McBreen, J.; Reilly, J.J.; Johnson, J.R.; Adzic, G.; Kumar, M.P.S. et al.
Item Type: Article

Effect of centrifugal force on the elastic curve of a vibrating cantilever beam

Description: A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondimensional basis for second and third mode vibration; the experiments were conducted on beams of various lengths, materials, and cross sections for second-mode vibration. From this investigation it was concluded that high vibratory-stress positions are unaffected by the addition of centrifugal force. Nonrotating vibration surveys of blades therefore are valuable in predicting high vibratory-stress locations under operating conditions.
Date: January 1, 1948
Creator: Simpkinson, Scott H; Eatherton, Laurel J & Millenson, Morton B
Item Type: Report

Effect of Centrifugal Transverse Wakefield for Microbunch in Bend

Description: We calculate centrifugal force for a short bunch in vacuum moving in a circular orbit and estimate the emittance growth of the beam in a bend due to this force. Many of the basic features of the coherent synchrotron radiation (CSR) of short bunches and its effect on beam dynamics in accelerators are now well established. The effect is usually described in terms of the longitudinal force, or wakefield, that causes the energy loss in the beam, and also redistributes the energy between the particles by accelerating the head and decelerating the tail of the bunch. Coherent radiation becomes most important for short bunches and high currents. More subtle features of CSR such as transition effect due to the entrance to and exit from the bend, CSR force in the undulator, and shielding due to the close metallic boundaries have been also studied. Much less is known about the transverse force in a short bunch moving on a circular orbit. The problem has been treated in several papers beginning from R. Talman's work, who pointed out that the centrifugal force of a rotating bunch can result in a noticeable tune shift of betatron oscillations. Later, an important correction to the Talman paper has been added, where it was shown that due to the energy variation in the bunch, the effect of the transverse force proportional to R{sup -1} is canceled, and the residual effect is of the order of R{sup -2}, that is much smaller than originally predicted. Recently, however, Derbenev and Shiltsev found the centrifugal force of the order of R{sup -1} that differs from Talman's result by a logarithmic factor only. Taking into account the existing controversy in the literature, in this paper, we consider the transverse force in a bunch based on simple physical arguments, starting from ...
Date: March 22, 2006
Creator: Stupakov, G.V. & /SLAC
Item Type: Article

Effect of cerium incorporation into zirconia on the activity ofCu/ZrO2 for methanol synthesis via CO hydrogenation

Description: The effects of Ce incorporation into ZrO2 on the catalyticperformance of Cu/ZrO2 for the hydrogenation of CO have beeninvestigated. A Ce0.3Zr0.7O2 solid solution was synthesized by forcedhydrolysis at low pH. After calcination at 873 K, XRD and Ramanspectroscopy characterization indicated that the Ce0.3Zr0.7O2 had a t''crystal structure. 1.2 wt percent Cu/Ce0.3Zr0.7O2 exhibited H2consumption peaks at low temperature (<473 K) during H2-TPRindicating a significant fraction (~; 70 percent) of Ce4+ is reduced toCe3+. 1.2 wt percent Cu/Ce0.3Zr0.7O2 is 2.7 times more active formethanol synthesis than 1.2 wt percent Cu/m-ZrO2 at 3.0 MPa attemperatures between 473 and 523 K and exhibits a higher selectivity tomethanol. In-situ infrared spectroscopy shows that, analogous toCu/m-ZrO2, the primary surface species on Cu/Ce0.3Zr0.7O2 during COhydrogenation are formate and methoxide species. A shift in the bandposition of the bridged methoxide species indicated that some of thesegroups were bonded to both Zr4+ and Ce3+ cations. For both catalysts, therate-limiting step for methanol synthesis is the reductive elimination ofmethoxide species. The higher rate of methanol synthesis onCu/Ce0.3Zr0.7O2 relative to Cu/m-ZrO2 was primarily due to a ~; 2.4 timeshigher apparent rate constant, kapp, for methoxide hydrogenation, whichis attributed to the higher surface concentration of H atoms on theformer catalyst. The increased capacity of the Ce-containing catalyst isattributed to interactions of H atoms with Ce-O pairs present at thesurface of the oxide phase.
Date: August 24, 2005
Creator: Pokrovski, Konstantin A.; Rhodes, Michael D. & Bell, Alexis T.
Item Type: Article

Effect of Cesium and Xenon Seeding in Negative Hydrogen Ion Sources

Description: It is well known that cesium seeding in volume hydrogen negative ion sources leads to a large reduction of the extracted electron current and in some cases to the enhancement of the negative ion current. The cooling of the electrons due to the addition of this heavy impurity was proposed as a possible cause of the mentioned observations. In order to verify this assumption, the authors seeded the hydrogen plasma with xenon, which has an atomic weight almost equal to that of cesium. The plasma properties were studied in the extraction region of the negative ion source Camembert III using a cylindrical electrostatic probe while the negative ion relative density was studied using laser photodetachment. It is shown that the xenon mixing does not enhance the negative ion density and leads to the increase of the electron density, while the cesium seeding reduces the electron density.
Date: September 6, 1999
Creator: Bacal, M.; Brunteau, A.M.; Deniset, C.; Elizarov, L.I.; Sube, F.; Tontegode, A.Y. et al.
Item Type: Article

Effect of Cesium Pressure on Thermionic Stability

Description: It is shown that under certain conditions of heat input, reservoir temperature, and load voltage or resistance a thermionic converter can equilibrate at two radically different operation points, corresponding to conditions of high and low cesium coverage. Moreover, abrupt transitions between these operating regimes, accompanied by a temperature rise of hundreds of degrees, can occur whenever the critical heat generation rate for a given reservoir temperature is exceeded. To provide an adequate safety margin against such an occurrence, thermionic systems must be operated at relatively high cesium pressures, even though this may cause some performance degradation. This paper consists of two parts. The first explains the above effect with reference to a single converter. The second part illustrates the effect of cesium reservoir temperatures on the dynamic behavior of an open-loop thermionic reactor following a small reactivity perturbation.
Date: August 1, 1969
Creator: Schock, Alfred
Item Type: Report

Effect of CH4 and O2 variations on rates of CH4 oxidation and stable isotope fractionation in tropical rain forest soils

Description: Methane-oxidizing bacteria are the primary sink for CH{sub 4} in reduced soils, and account for as much as 90 percent of all CH{sub 4} produced. Methanotrophic bacteria strongly discriminate against the heavy isotopes of carbon, resulting in CH{sub 4} emissions that are significantly more enriched in {sup 13}C than the original source material. Previous studies have used an isotope mass balance approach to quantify CH{sub 4} sources and sinks in the field, based on the assumption that the fractionation factor for CH{sub 4} oxidation is a constant. This study quantifies the effect of systematic variations in CH{sub 4} and O{sub 2} concentrations on rates of CH{sub 4} oxidation and stable isotope fractionation in tropical rain forest soils. Soils were collected from the 0-15 cm depth, and incubated with varying concentrations of CH{sub 4} (100 ppmv, 500 ppmv, 1000 ppmv, and 5000 ppmv) or O{sub 2} (3 percent, 5 percent, 10 percent, and 21 percent). The isotope fractionation factor for CH{sub 4} oxidation was calculated for each incubation using a Rayleigh fractionation model. Rates of CH{sub 4} oxidation varied significantly between CH{sub 4} treatments, with the 100 ppmv CH{sub 4} treatment showing the lowest rate of CH{sub 4} uptake, and the other 3 treatments showing similar rates of CH{sub 4} uptake. Rates of CH{sub 4} oxidation did not vary significantly between the different O{sub 2} treatments. The fractionation factor for CH{sub 4} oxidation varied significantly between the different CH{sub 4} treatments, with the 5000 ppmv CH{sub 4} treatment showing the largest {sup 13}C-enrichment of residual CH{sub 4}. In treatments where CH{sub 4} concentration was not rate-limiting (&gt; 500 ppmv CH{sub 4}), the fractionation factor for CH{sub 4} oxidation was negatively correlated with CH{sub 4} oxidation rate (P &lt; 0.003, r{sup 2} = 0.86). A multiple regression model that included initial CH{sub ...
Date: October 1, 2003
Creator: Teh, Yit Arn; Conrad, Mark; Silver, Whendee L. & Carlson, Charlotte M.
Item Type: Article

Effect of Changes in Aileron Rigging on the Stick Forces of a High-Speed Fighter Airplane

Description: The effects of changes in aileron rigging between 2 deg up and 2 deg down on the stick forces were determined from wind-tunnel data for a finite-span wing model. These effects were investigated for ailerons deflecting equally in both directions and linearly with stick deflection. Data were analyzed for a Frise, a sealed internally balanced, and a beveled-trailing-edge aileron. The results of the analysis showed that only ailerons having linear hinge-moment characteristics are unaffected by changes in rigging and indicated that ailerons having decidedly nonlinear hinge-moment-coefficient curves, particularly for deflections near 0 deg, are very sensitive to changes in rigging.
Date: May 1, 1944
Creator: Murray, Harry E. & Warren, S Anne
Item Type: Report

The effect of changes in compression ratio upon engine performance

Description: This report is based upon engine tests made at the Bureau of Standards during 1920, 1921, 1922, and 1923. The majority of these tests were of aviation engines and were made in the Altitude Laboratory. For a small portion of the work a single cylinder experimental engine was used. This, however, was operated only at sea-level pressures. The report shows that an increase in break horsepower and a decrease in the pounds of fuel used per brake horsepower hour usually results from an increase in compression ratio. This holds true at least up to the highest ratio investigated, 14 to 1, provided there is no serious preignition or detonation at any ratio. To avoid preignition and detonation when employing high-compression ratios, it is often necessary to use some fuel other than gasoline. It has been found that the consumption of some of these fuels in pounds per brake horsepower hour is so much greater than the consumption of gasoline that it offsets the decrease derived from the use of the high-compression ratio. The changes in indicated thermal efficiency with changes in compression ratio are in close agreement with what would be anticipated from a consideration of the air cycle efficiencies at the various ratios. In so far as these tests are concerned there is no evidence that a change in compression ratio produces an appreciable, consistent change in friction horsepower, volumetric efficiency, or in the range of fuel-air ratios over which the engine can operate. The ratio between the heat loss to the jacket water and the heat converted into brake horsepower or indicated horsepower decreases with increase in compression ratio. (author).
Date: January 1, 1925
Creator: Sparrow, Stanwood W
Item Type: Report

Effect of changes in tail arrangement upon the spinning of a low-wing monoplane model

Description: A series of tests was made in the N.A.C.A. free spinning tunnel to find the effect upon spinning characteristics of systematic changes in tail arrangement. The tests were made with a 1/16-scale made of a low-wing monoplane of modern design. The changes consisted of: (1) variation of the fuselage length; (2) variation of the fore-and-aft location of the vertical surfaces; and (3) variation of the vertical location of the horizontal surfaces. The spinning characteristics of the model, including the number of turns required for recovery, were found to vary systematically and regularly with systematic changes in the tail arrangement. The following changes in tail arrangement had harmful effects upon the recovery characteristics (which originally were excellent): (1) shortening the fuselage; (2) placing the vertical surfaces directly above the horizontal surfaces as compared with locations either fore or aft of this position; (3) moving the horizontal surfaces downward from their original location at the top of the fuselage.
Date: June 1, 1936
Creator: Zimmerman, C H
Item Type: Report

Effect of changing the mean camber of an airfoil section

Description: Methodical experiments with the series of airfoil sections of the same relative thickness and of variable relative cambers can be utilized for determining the effect of the camber on the aerodynamic properties of airfoil sections.
Date: March 1, 1924
Creator: Toussaint, A.
Item Type: Report