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Sample records for metallographic cooling rates

  1. Metallographic Cooling Rate of IVA Irons Revisited

    NASA Technical Reports Server (NTRS)

    Yang, J.; Goldstein, J. I.; Scott, E. R. D.

    2005-01-01

    There is long standing problem reconciling the chemical evidence that the IVA iron meteorites formed in a core with the diverse cooling rates reported by several researchers. This large inferred range of cooling rates suggests that the IVA irons were distributed at different depths in a parent body with a complex structure when the Widmanstatten pattern formed. On the other hand, some researchers argued that the diverse cooling rates in group IVA result from inaccurate model parameters such as phase diagram, interdiffusion coefficients, and kamacite nucleation and growth mechanisms. In addition, the measured cooling rates may not apply for the same cooling temperature ranges, and the variation in the crystallographic orientations of the Widmanstatten plates on the analysis surface may result in inaccurate measurements of widths needed for the computer simulation models. We have revaluated the major parameters in computer model developed by Hopfe and Goldstein and measured cooling rates for the IVA irons. Such data are useful in evaluating whether these meteorites were part of a single core of a parent body during the formation of the Widmanstatten pattern.

  2. Metallographic cooling rates of L-group ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Bennett, Marvin E.; Mcsween, Harry Y., Jr.

    1993-01-01

    Shock metamorphism appears to be a ubiquitous feature in L-group ordinary chondrites. Brecciation and heterogeneous melting obscure much of the early history of this meteorite group and have caused confusion as to whether L chondrites have undergone thermal metamorphism within onion-shell or rubble-pile parent bodies. Employing the most recent shock criteria, we have examined 55 Antarctic and 24 non-Antarctic L chondrites in order to identify those which have been least affected by post-accretional shock. Six low-shock samples (those with shock grade less than S4) of petrographic types L3-L5 were selected from both populations and metallographic cooling rates were obtained following the technique of Willis and Goldstein. All non-Antarctic L6 chondrites inspected were too heavily shocked to be included in this group. However, 4 shocked L6 chondrites were analyzed in order to determine what effects shock may impose on metallographic cooling rates. Metallographic cooling rates were derived by analyzing the cores of taenite grains and then measuring the distance to the nearest grain edge. Taenites were identified using backscatter imaging on a Cameca SX-50 electron microprobe. Using backscatter we were able to locate homogeneous, rust-free, nearly spherical grains. M-shaped profiles taken from grain traverses were also used to help locate the central portions of selected grains. All points which contained phosphorus above detection limits were discarded. Plots of cooling-rate data are summarized and data from the high-shock samples are presented. The lack of coherency of cooling rates for individual samples is indicative of heterogeneous cooling following shock. The data confirms the statement expressed by numerous workers that extreme care must be taken when selecting samples of L chondrites for cooling-rate studies. Data for the 6 non-Antarctic low-shock samples are also presented. The samples display a general trend in cooling rates. The lowest metamorphic grade

  3. A Comparison of Metallographic Cooling Rate Methods Used in Meteorites

    NASA Technical Reports Server (NTRS)

    Herpfer, Marc A.; Larimer, John W.; Goldstein, J. I.

    1994-01-01

    cooling times inferred from the cooling rates suggests that the parent body cooled more slowly after the metallographic cooling rates were established.

  4. Implications for Metallographic Cooling Rates, Derived from Fine-Scale Analytical Traverses Across Kamacite, Taenite, and Tetrataenite in the Butler Iron Meteorite

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Ross, D. K.; Chabot, N. L.; Keller, L. P.

    2016-01-01

    The "M-shaped" Ni concentrations across Widmanstatten patterns in iron meteorites, mesosiderites, and ordinary chondrites are commonly used to calculate cooling rates. As Ni-poor kamacite exolves from Ni-rich taenite, Ni concentrations build up at the kamacite-taenite interface because of the sluggish diffusivity of Ni. Quantitative knowledge of experimentally-determined Ni diffusivities, coupled with the shape of the M-profile, have been used to allow calculation of cooling rates that pertained at low temperatures, less than or equal to 500 C. However, determining Ni metallographic cooling rates are challenging, due to the sluggish diffusivity of Ni at low temperatures. There are three potential difficulties in using Ni cooling rates at low temperatures: (i) Ni diffusivities are typically extrapolated from higher-temperature measurements; (ii) Phase changes occur at low temperatures that may be difficult to take into account; and (iii) It appears that Ge in kamacite and taenite has continued to equilibrate (or attempted to equilibrate) at temperatures below those that formed the M-shaped Ni profile. Combining Ni measurements with those of other elements has the potential to provide a way to confirm or challenge Ni-determined cooling rates, as well as provide insight into the partitioning behaviors of elements during the cooling of iron meteorites. Despite these benefits, studies that examine elemental profiles of Ni along with other elements in iron meteorites are limited, often due to the low concentration levels of the other elements and associated analytical challenges. The Butler iron meteorite provides a good opportunity to conduct a multi-element analytical study, due to the higher concentration levels of key elements in addition to Fe and Ni. In this work, we perform combined analysis for six elements in the Butler iron to determine the relative behaviors of these elements during the evolution of iron meteorites, with implications for metallographic cooling

  5. Relative Metallographic Cooling Rates: Can They be Measured Using Co/Ni Ratios at Taenite/Kamacite Interfaces?

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Yang, J.; Scott, E. R. D.

    2012-09-01

    The relative cooling rates of IVA and IIIAB irons obtained recently by Wasson and Hoppe must be treated with much caution as they were obtained with inadequate spatial resloution and a flowed phase diagram and methodology.

  6. The Effect of Early Impacts on Iron Meteorite Cooling Rates

    NASA Astrophysics Data System (ADS)

    Lyons, R. J.; Ciesla, F. J.; Bowling, T. J.; Davison, T. M.; Collins, G. S.

    2016-08-01

    Sizes and structures of iron meteorite parent bodies have been inferred by comparing metallographic cooling rates to thermal evolution models. We examine the effect that impacts would have on cooling rates of cores of differentiated planetesimals.

  7. Cooling rates and parent bodies of iron meteorites from group IIICD, IAB, and IVB

    NASA Astrophysics Data System (ADS)

    Rasumssen, K. L.

    1989-03-01

    Metallographic cooling rates for the iron meteorites Carlton (IIICD), Toluca (IAB), and Odessa (IAB) are calculated using the central Ni concentration versus taenite width method. For members of group IVB, the ungrouped iron meteorite Chinga, and the high-Ni members of IIICD and IAB, kamacite bandwidth cooling rates are determined. The cooling rates are up to several orders of magnitude faster than those from previous calculations.

  8. Cation ordering in orthopyroxenes and cooling rates of meteorites: Low temperature cooling rates of Estherville, Bondoc and Shaw

    NASA Technical Reports Server (NTRS)

    Ganguly, J.; Yang, H.; Ghose, S.

    1993-01-01

    The cooling rates of meteorites provide important constraints on the size of their parent bodies, and their accretionary and evolutionary histories. However, the cooling rates obtained so far from the commonly used metallographic, radiometric and fission-track methods have been sometimes quite controversial, such as in the case of the mesosiderites and the meteorite Shaw. We have undertaken a systematic study of the cooling rates of meteorites using a different approach, which involves single crystal x-ray determination of Fe(2+)-Mg ordering in orthopyroxenes (OP(x)) in meteorites, subject to bulk compositional constraints, and numerical simulation of the evolution of the ordering state as a function of cooling rate, within the framework of the thermodynamic and kinetic principles governing cation ordering. We report the results obtained for OP(x) crystals from Shaw and two mesosiderites, Estherville and Bondoc.

  9. Postexercise Cooling Rates in 2 Cooling Jackets

    PubMed Central

    Brade, Carly; Dawson, Brian; Wallman, Karen; Polglaze, Ted

    2010-01-01

    Abstract Context: Cooling jackets are a common method for removing stored heat accumulated during exercise. To date, the efficiency and practicality of different types of cooling jackets have received minimal investigation. Objective: To examine whether a cooling jacket containing a phase-change material (PC17) results in more rapid postexercise cooling than a gel cooling jacket and a no-jacket (control) condition. Design: Randomized, counterbalanced design with 3 experimental conditions. Setting: Participants exercised at 75% V̇o2max workload in a hot climate chamber (temperature  =  35.0 ± 1.4°C, relative humidity  =  52 ± 4%) for 30 minutes, followed by postexercise cooling for 30 minutes in cool laboratory conditions (ambient temperature  =  24.9 ± 1.8°C, relative humidity  =  39% ± 10%). Patients or Other Participants: Twelve physically active men (age  =  21.3 ± 1.1 years, height  =  182.7 ± 7.1 cm, body mass  =  76.2 ± 9.5 kg, sum of 6 skinfolds  =  50.5 ± 6.9 mm, body surface area  =  1.98 ± 0.14 m2, V̇o2max  =  49.0 ± 7.0 mL·kg−1·min−1) participated. Intervention(s): Three experimental conditions, consisting of a PC17 jacket, a gel jacket, and no jacket. Main Outcome Measure(s): Core temperature (TC), mean skin temperature (TSk), and TC cooling rate (°C/min). Results: Mean peak TC postexercise was 38.49 ± 0.42°C, 38.57 ± 0.41°C, and 38.55 ± 0.40°C for the PC17 jacket, gel jacket, and control conditions, respectively. No differences were observed in peak TC cooling rates among the PC17 jacket (0.038 ± 0.007°C/min), gel jacket (0.040 ± 0.009°C/min), and control (0.034 ± 0.010°C/min, P > .05) conditions. Between trials, no differences were calculated for mean TSk cooling. Conclusions: Similar cooling rates for all 3 conditions indicate that there is no benefit associated with wearing the PC17 or gel jacket. PMID:20210620

  10. Co/Ni ratios at taenite/kamacite interfaces and relative cooling rates in iron meteorites

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Hoppe, Peter

    2012-05-01

    We report a pilot study of a new technique to use the distribution of Co between kamacite and taenite to infer relative cooling rates of iron meteorites; data of Widge and Goldstein (1977) showed that the distribution is temperature dependent. A plot of the logarithm of the double ratio [(Co/Ni)kamacite/(Co/Ni)taenite] (abbreviated Rαγ) against inverse temperature yields a linear equation showing that the ratio ranges from ˜2.5 at 1080 K to ˜30 at 710 K. Thus, a measurement of Rαγ in the kamacite and taenite near the interface offers information about relative cooling rates; the higher Rαγ, the lower the cooling rate. A major advantage of this technique is that it is mainly affected by the final (low-temperature) cooling rate, just before the sample cooled to the blocking temperature where diffusion became insignificant. To test this method we used the NanoSIMS ion probe to measure Rαγ in two IVA and two IIIAB irons; members of each pair differ by large factors in elemental composition and in published metallographic cooling rates (Yang and Goldstein, 2006; Yang et al., 2008). Despite differing by a factor of 25 in estimated metallographic cooling rate, the two IVA irons showed similar Rαγ values of ˜22. If experimental uncertainties are considered this implies that, at low temperatures, their cooling rates differ by less than a factor of 5 with 95% confidence, i.e., significantly less than the range in metallographic cooling rates. In contrast, the IIIAB irons have different ratios; Rαγ in Haig is 29 whereas that in Cumpas, with a reported cooling rate 4.5 times lower, is 22, the opposite of that expected from the published cooling rates. A reevaluation of the Yang-Goldstein IIIAB data set shows that Haig has anomalous metallographic properties. We suggest that both the high Rαγ in Haig and the systematically low taenite central Ni contents are the result of impact-produced fractures in the taenite that allowed equilibration with kamacite down to

  11. New fine structure cooling rate

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.

    1976-01-01

    One of the dominant electron cooling processes in the ionosphere is caused by electron impact induced fine structure transitions among the ground state levels of atomic oxygen. This fine structure cooling rate is based on theoretical cross sections. Recent advances in the numerical cross section determinations to include polarization effects and more accurate representations of the atomic target result in new lower values. These cross sections are employed in this paper to derive a new fine structure cooling rate which is between 40% and 60% of the currently used rate. A new generalized formula is presented for the cooling rate (from which the fine structure cooling rate is derived), valid for arbitrary mass and temperature difference of the colliding particles and arbitrary inelastic energy difference.

  12. Cooling rates of group IVA iron meteorites

    NASA Technical Reports Server (NTRS)

    Willis, J.; Wasson, J. T.

    1978-01-01

    Cooling rates of six group IVA iron meteorites were estimated by a taenite central Ni concentration-taenite half-width method. Calculated cooling rates range from 13 to 25 C/Myr, with an average of 20 C/Myr. No correlation between cooling rate and bulk Ni content is observed, and the data appear to be consistent with a uniform cooling rate as expected from an igneous core origin. This result differs from previous studies reporting a wide range in cooling rates that were strongly correlated with bulk Ni content. The differences result mainly from differences in the phase diagram and the selected diffusion coefficients. Cooling rates inferred from taenite Ni concentrations at the interface with kamacite are consistent with those based on taenite central Ni content.

  13. Cooling rate calculations for silicate glasses.

    NASA Astrophysics Data System (ADS)

    Birnie, D. P., III; Dyar, M. D.

    1986-03-01

    Series solution calculations of cooling rates are applied to a variety of samples with different thermal properties, including an analog of an Apollo 15 green glass and a hypothetical silicate melt. Cooling rates for the well-studied green glass and a generalized silicate melt are tabulated for different sample sizes, equilibration temperatures and quench media. Results suggest that cooling rates are heavily dependent on sample size and quench medium and are less dependent on values of physical properties. Thus cooling histories for glasses from planetary surfaces can be estimated on the basis of size distributions alone. In addition, the variation of cooling rate with sample size and quench medium can be used to control quench rate.

  14. Experimental and Numerical Investigation on the Phase Separation Affected by Cooling Rates and Marangoni Convection in Cu-Cr Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Fei; von Klinski-Wetzel, Katharina; Mukherjee, Rajdip; Nestler, Britta; Heilmaier, Martin

    2015-04-01

    In this work, we study the microstructures upon rapid solidification from the melt which occurs in Cu-Cr electrical contacts after switching operations. As the local cooling rates are difficult to be determined experimentally, we numerically compute the mean radius of Cr-particles from phase separation as a function of the cooling rate by utilizing a convective Cahn-Hilliard model. Based on the computationally derived correlation and on the metallographically observed microstructure, we are able to extract back the local cooling rates during heat treatment. We further examine the effect of Marangoni convection on the phase separation structure in a particularly composed simulation study. We obtain the cooling rate for a given particle size affected by the solutal Marangoni convection.

  15. Abundances of volatile-bearing phases in carbonaceous chondrites and cooling rates of meteorites based on cation ordering of orthopyroxenes

    NASA Technical Reports Server (NTRS)

    Ganguly, Jibamitra

    1989-01-01

    Results of preliminary calculations of volatile abundances in carbonaceous chondrites are discussed. The method (Ganguly 1982) was refined for the calculation of cooling rate on the basis of cation ordering in orthopyroxenes, and it was applied to the derivation of cooling rates of some stony meteorites. Evaluation of cooling rate is important to the analysis of condensation, accretion, and post-accretionary metamorphic histories of meteorites. The method of orthopyroxene speedometry is widely applicable to meteorites and would be very useful in the understanding of the evolutionary histories of carbonaceous chondrites, especially since the conventional metallographic and fission track methods yield widely different results in many cases. Abstracts are given which summarize the major conclusions of the volatile abundance and cooling rate calculations.

  16. Electron cooling rates characterization at Fermilab's Recycler

    SciTech Connect

    Prost, Lionel R.; Shemyakin, A.; /Fermilab

    2007-06-01

    A 0.1 A, 4.3 MeV DC electron beam is routinely used to cool 8 GeV antiprotons in Fermilab's Recycler storage ring [1]. The primary function of the electron cooler is to increase the longitudinal phase-space density of the antiprotons for storing and preparing high-density bunches for injection into the Tevatron. The longitudinal cooling rate is found to significantly depend on the transverse emittance of the antiproton beam. The paper presents the measured rates and compares them with calculations based on drag force data.

  17. The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

    NASA Astrophysics Data System (ADS)

    Fabrizi, A.; Timelli, G.

    2016-03-01

    This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al15(Fe,Mn,Cr)3Si2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al5(Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates.

  18. Determining cooling rates of iron and stony-iron meteorites from measurements of Ni and Co at kamacite-taenite interfaces

    NASA Astrophysics Data System (ADS)

    Goldstein, Joseph I.; Yang, Jijin; Scott, Edward R. D.

    2014-09-01

    Analyses and modeling of Ni zoning in taenite in differentiated meteorites provide metallographic cooling rates at ∼500 °C that are inconsistent with conventional formation models. Group IVA iron meteorites have very diverse cooling rates of 100-6600 °C/Myr indicating that they cooled inside a large metallic body with little or no silicate mantle (Yang et al., 2007). Wasson and Hoppe (2012) have questioned these diverse cooling rates on the basis of their ion probe measurements of Ni/Co ratios at the kamacite-taenite interface in two group IVA and in two group IIIAB iron meteorites. To investigate their claims and to assess methods for determining relative cooling rates from kamacite-taenite interface compositions, we have analyzed 38 meteorites-13 IVA, 14 IIIAB irons, 4 IAB complex irons, 6 pallasites and a mesosiderite-using the electron probe microanalyzer (EPMA). Ni concentrations in taenite (Niγ) and kamacite (Niα) at kamacite-taenite interfaces are well correlated with metallographic cooling rates: Niγ values increase from 30 to 52 wt.% while Niα decreases from 7 to 4 wt.% as cooling rates decrease. EPMA measurements of Niγ, Niα, and Niα/Niγ, can therefore be used to provide order-of-magnitude estimates of relative cooling rates. Concentrations of Co in kamacite and taenite at their interface (Coα, Coγ) are controlled by bulk Ni and Co composition, as well as cooling rate. The ratios Coα/Coγ and (Co/Ni)α/(Co/Ni)γ are correlated with cooling rate, but because of significant scatter, these parameters should not be used to estimate cooling rates. Our analyses of 13 group IVA irons provide robust support for diverse cooling rates that decrease with increasing bulk Ni, consistent with measurements of cloudy zone size and tetrataenite width. Apparent equilibration temperatures, which are inferred from Niγ values and the Fe-Ni-P phase diagram and Ni diffusion rates in taenite, show that cooling rates of IVA irons vary by a factor of ≈100, in

  19. Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments.

    SciTech Connect

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.

    2008-05-05

    In light water reactors, components made of nickel-base alloys are susceptible to environmentally assisted cracking. This report summarizes the crack growth rate results and related metallography for field and laboratory-procured Alloy 600 and its weld alloys tested in pressurized water reactor (PWR) environments. The report also presents crack growth rate (CGR) results for a shielded-metal-arc weld of Alloy 182 in a simulated PWR environment as a function of temperature between 290 C and 350 C. These data were used to determine the activation energy for crack growth in Alloy 182 welds. The tests were performed by measuring the changes in the stress corrosion CGR as the temperatures were varied during the test. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. These values are in good agreement with the data reported in the literature. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the order of 220-230 kJ/mol, higher than the 130 kJ/mol commonly used for Alloy 600. The consequences of using a larger value of activation energy for SCC CGR data analysis are discussed.

  20. Relative cooling rates derived from basalt column geometries

    NASA Astrophysics Data System (ADS)

    Woodell, Daniel; Porritt, Lucy; Russell, Kelly

    2015-04-01

    Columnar joints form as a brittle relaxation response to tensile stresses that accumulate during cooling of lava flows, pyroclastic deposits, and intrusive magma bodies. Columnar jointing forms in different deposit types, in deposits of different compositions, and different outcrop geometries. Despite this diversity, columns follow a few "rules": column diameter is inversely proportional to cooling rate (small/quick cooling times, small diameter columns), columns only ever coalesce (never bifurcate), and columnar joints always propagate parallel to but in the opposite direction of heat flow (towards the hottest part of the flow). Using these "rules," cooling histories and emplacement environments can be reconstructed. While column geometries and definitions of various columnar structures vary between authors (upper and lower colonnade and entablature vs. master cracks and pseudopillows), this study focuses on relatively simple outcrops of basalt lava within the Cheakamus River valley near Whistler, BC, Canada. The basalt lavas described here, thought to have erupted subglacially, contain columns comprising only well-defined upper and lower colonnades (i.e., no entablature). Comparing the relative thicknesses of upper and lower colonnades reveals the cooling history, relative cooling rates, and amounts of heat transferred from the upper and lower flow boundaries. Forward numerical models using the finite element method are created with Matlab using the Partial Differential Equation Toolbox to model the outcrops in the Whistler field area, and determine the cooling rates and thermal gradients experienced by the lava flows during their formation. This study finds that noticeable differences in the thickness of upper and lower colonnades within an outcrop occur only when there are large differences in cooling rates between the upper and lower flow surfaces. Modeling shows that the cooling rates must differ by approximately an order of magnitude to produce the observed

  1. Effect of tropospheric aerosols upon atmospheric infrared cooling rates

    NASA Technical Reports Server (NTRS)

    Harshvardhan, MR.; Cess, R. D.

    1978-01-01

    The effect of tropospheric aerosols on atmospheric infrared cooling rates is investigated by the use of recent models of infrared gaseous absorption. A radiative model of the atmosphere that incorporates dust as an absorber and scatterer of infrared radiation is constructed by employing the exponential kernel approximation to the radiative transfer equation. Scattering effects are represented in terms of a single scattering albedo and an asymmetry factor. The model is applied to estimate the effect of an aerosol layer made of spherical quartz particles on the infrared cooling rate. Calculations performed for a reference wavelength of 0.55 microns show an increased greenhouse effect, where the net upward flux at the surface is reduced by 10% owing to the strongly enhanced downward emission. There is a substantial increase in the cooling rate near the surface, but the mean cooling rate throughout the lower troposphere was only 10%.

  2. Boar semen can tolerate rapid cooling rates prior to freezing.

    PubMed

    Juarez, Jorge D; Parrilla, Inma; Vazquez, Juan M; Martinez, Emilio A; Roca, Jordi

    2011-01-01

    Two experiments were performed in the present study that demonstrated that boar spermatozoa are capable of surviving rapid cooling rates within a range of 15-5 °C before freezing. Boar ejaculates diluted in Beltsville thawing solution (BTS) (1:1, v/v) were held at 17-20 °C and shipped over a 24-h time period from two AI centres to a cryobiology laboratory, where they were pooled (Experiment 1) or cryopreserved individually (Experiment 2) using a standard 0.5-mL straw freezing protocol. The effects of cooling before freezing were assessed after thawing through the objective evaluation of sperm motility and flow cytometric analysis of membrane integrity, acrosomal status, changes in membrane lipid architecture monitored by merocyanine and annexin V binding and intracellular production of reactive oxygen species. In Experiment 1 (six replicates), two semen pools (five ejaculates per pool) were cooled from 15 to 5 °C at rates of 0.08, 0.13, 0.40 and 1.50 °C min(-1). These cooling rates did not result in any significant differences (P>0.05) in any of the post-thaw sperm assessments, even in thawed samples incubated under capacitation conditions. In Experiment 2, three individual ejaculates from 16 boars were slowly (0.08 °C min(-1)) or rapidly (1.5 °C min(-1)) cooled before freezing. A consistent interboar variability (P<0.01) was detected, which was independent of the cooling rate used. Cooling rate only significantly influenced (P<0.05) sperm assessments in four of 16 boars, which exhibited slightly higher percentages of motile cells and intact plasma and acrosomal membranes in the samples that had been cooled slowly. These findings demonstrate that boar spermatozoa undergoing cryopreservation can withstand rapid cooling rates before freezing. PMID:21635817

  3. Computation of infrared cooling rates in the water vapor bands

    NASA Technical Reports Server (NTRS)

    Chou, M. D.; Arking, A.

    1978-01-01

    A fast but accurate method for calculating the infrared radiative terms due to water vapor has been developed. It makes use of the far wing approximation to scale transmission along an inhomogeneous path to an equivalent homogeneous path. Rather than using standard conditions for scaling, the reference temperatures and pressures are chosen in this study to correspond to the regions where cooling is most significant. This greatly increased the accuracy of the new method. Compared to line by line calculations, the new method has errors up to 4% of the maximum cooling rate, while a commonly used method based upon the Goody band model (Rodgers and Walshaw, 1966) introduces errors up to 11%. The effect of temperature dependence of transmittance has also been evaluated; the cooling rate errors range up to 11% when the temperature dependence is ignored. In addition to being more accurate, the new method is much faster than those based upon the Goody band model.

  4. Computation of infrared cooling rates in the water vapor bands

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Arking, A.

    1980-01-01

    A fast and accurate method is developed for calculating the infrared radiative terms due to water vapor - specifically, the atmospheric cooling rates. The accuracy is achieved by avoiding the constraints of band models and working directly with the absorption coefficient, which is a function of temperature and pressure as well as wavenumber. The method is based on calculation of an equivalent water vapor amount between atmospheric pressure levels and a table look-up procedure. Compared to line-by-line calculations, the present method has errors up to 4% of the maximum cooling rate. The use of a scaling factor, based on the far-wing approximation, limits the applicability of the method to the troposphere and lower stratosphere, where the line wings are responsible for most of the radiative cooling associated with water vapor.

  5. A liquid cooled garment temperature controller based on sweat rate

    NASA Technical Reports Server (NTRS)

    Chambers, A. B.; Blackaby, J. R.

    1972-01-01

    An automatic controller for liquid cooled space suits is reported that utilizes human sweat rate as the primary input signal. The controller is so designed that the coolant inlet temperature is inversely proportional to the subject's latent heat loss as evidenced by evaporative water loss.

  6. Field drying rate differences among three cool-season grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conserving cool-season grasses as silage or hay remains a challenge due to the time required for curing and the unpredictability of weather. We compared the drying rates of three grasses with differing yield potential, morphology, and physical characteristics. Inflorescence-stage meadow fescue, orch...

  7. MEASURING THE EVOLUTIONARY RATE OF COOLING OF ZZ Ceti

    SciTech Connect

    Mukadam, Anjum S.; Fraser, Oliver; Riecken, T. S.; Kronberg, M. E.; Bischoff-Kim, Agnes; Corsico, A. H.; Montgomery, M. H.; Winget, D. E.; Hermes, J. J.; Winget, K. I.; Falcon, Ross E.; Reaves, D.; Kepler, S. O.; Romero, A. D.; Chandler, D. W.; Kuehne, J. W.; Sullivan, D. J.; Von Hippel, T.; Mullally, F.; Shipman, H.; and others

    2013-07-01

    We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series photometry from 1970 November to 2012 January, we determine the rate of change of this period with time to be dP/dt = (5.2 {+-} 1.4) Multiplication-Sign 10{sup -15} s s{sup -1} employing the O - C method and (5.45 {+-} 0.79) Multiplication-Sign 10{sup -15} s s{sup -1} using a direct nonlinear least squares fit to the entire lightcurve. We adopt the dP/dt obtained from the nonlinear least squares program as our final determination, but augment the corresponding uncertainty to a more realistic value, ultimately arriving at the measurement of dP/dt = (5.5 {+-} 1.0) Multiplication-Sign 10{sup -15} s s{sup -1}. After correcting for proper motion, the evolutionary rate of cooling of ZZ Ceti is computed to be (3.3 {+-} 1.1) Multiplication-Sign 10{sup -15} s s{sup -1}. This value is consistent within uncertainties with the measurement of (4.19 {+-} 0.73) Multiplication-Sign 10{sup -15} s s{sup -1} for another similar pulsating DA white dwarf, G 117-B15A. Measuring the cooling rate of ZZ Ceti helps us refine our stellar structure and evolutionary models, as cooling depends mainly on the core composition and stellar mass. Calibrating white dwarf cooling curves with this measurement will reduce the theoretical uncertainties involved in white dwarf cosmochronometry. Should the 213.13 s period be trapped in the hydrogen envelope, then our determination of its drift rate compared to the expected evolutionary rate suggests an additional source of stellar cooling. Attributing the excess cooling to the emission of axions imposes a constraint on the mass of the hypothetical axion particle.

  8. Metallographic preparation techniques for ceramic materials

    SciTech Connect

    Saenz, N.T.

    1990-10-01

    With the increasing use of ceramic materials in many industrial areas, applied metallographic sample preparation techniques are used to produce true microstructural detail in ceramic materials. Due to the extreme hardness, porosity and brittleness of ceramic materials, improper ceramic preparation techniques tend to cause intergranular relief, grain plucking, grain fracturing, or other undesirable effects. Because of these inherent characteristics, care must be taken in the preparation of ceramic material. For example, defects such as cracking of the specimen can be initiated during the sectioning step and can also occur if improper mounting procedures are used. Pullout of grains which result from improper sectioning or a grinding technique that is too severe can also cause problems in later stages of preparation. To minimize any defects or a false microstructure, the metallographer must not only preform each step of sample preparation accurately, but must also have a clear understanding of the intended purpose for each specific sequence of preparation steps. 3 refs., 6 figs.

  9. Textural evolution of polyhedral olivine experiencing rapid cooling rates

    NASA Astrophysics Data System (ADS)

    Faure, François; Schiano, Pierre; Trolliard, Gilles; Nicollet, Christian; Soulestin, Bernard

    2007-04-01

    Dynamic crystallization experiments in the CaO MgO Al2O3 SiO2 (CMAS) system have been used to investigate the change in crystal shape when pre-existing polyhedral olivine crystals are cooled rapidly (1,639 2,182°C/h). Polyhedral olivines are crystallized initially in a first step using a slow cooling rate (2°C/h), then skeletal and dendritic overgrowths develop on the polyhedral crystals during a subsequent fast cooling event. During this second episode small dendritic olivines also nucleate within the liquid phase. Observation of the experimental sample by optical microscopy shows that the polyhedral olivine shape progressively changes to a skeletal and then to a dendritic morphology in the following sequence: polyhedral ⇒ hopper polyhedral ⇒ dendritic polyhedral. This evolutional sequence is discussed in terms of changes in the crystal growth conditions during cooling and a general relation between these olivine dynamic crystallization experiments and the integrated model of crystal growth by Sunagawa (Bull Minér 104:81 87, 1981, Morphology of crystals, Terra Scientific Publishing Company, 1987) is proposed.

  10. Computation of Infrared Cooling Rates in the Water Vapor Bands.

    NASA Astrophysics Data System (ADS)

    Chou, Ming Dah; Arking, Albert

    1980-04-01

    Ming Dah Chou and Albert ArkingLaboratory for Atmospheric Sciences, Goodard Space Flight Center, Greenbelt, MD 20771A fast but accurate method for calculating the infrared radiative terms due to water vapor has been developed. It makes use of the behavior in the far wings of absorption lines to scale transmission along an inhomogencous path to an equivalent homogeneous path. Rather than using standard conditions for scaling, the reference temperatures and pressures are chosen in this study to correspond to the-regions where cooling is most significant. This greatly increases the accuracy of the new method. Compared to line-by-line calculations, the new method has errors up to 4% of the maximum cooling rate, while a commonly used method based on the Goody band model (Rodgers and Walshaw, 1966) introduces errors up to 11%. The effect of temperature dependence of transmittance has also been evaluated; the cooling rate errors range up to 11% when the temperature-dependence is ignored. In addition to being more accurate, the new method is much faster than those based on the Goody band model.

  11. Hotter, Faster: A Thermal Model for the H-Chondrite Parent Body Consistent with Chronology and Cooling Rates

    NASA Astrophysics Data System (ADS)

    McSween, H. Y., Jr.; Bennett, M. E., III

    1995-09-01

    predicts post-metamorphic cooling rates through the temperature interval 800-500K of 26 K/Ma for H4, 22 K/Ma for H5, and 16 K/Ma for H6. These values approximately coincide, in both trend and magnitude, with metallographic and fission track cooling rate data for unshocked H chondrites [Lipschutz et al]. _

  12. Relative Cooling Rates of Meteoritic Fe-Ni Metal Determined from Kamacite-Taenite Interface Compositions

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Yang, J.; Scott, E. R. D.

    2013-09-01

    The validity of the kamacite/taenite interface method to obtain relative metallorgaphic cooling rates was reinvestigated. Strong support is found for the 50 fold variation in cooling rate across the IVA chemical group.

  13. Modeling Cooling Rates of Martian Flood Basalt Columns

    NASA Astrophysics Data System (ADS)

    Weiss, D. K.; Jackson, B.; Milazzo, M. P.; Barnes, J. W.

    2011-12-01

    Columnar jointing in large basalt flows have been extensively studied and can provide important clues about the emplacement conditions and cooling history of a basalt flow. The recent discovery of basalt columns on Mars in crater walls near Marte Vallis provides an opportunity to infer conditions on early Mars when the Martian basalt flows were laid down. Comparison of the Martian columns to Earth analogs allows us to gain further insight into the early Martian climate, and among the best terrestrial analogs are the basalt columns in the Columbia River Basalt Group (CRBG) in eastern Washington. The CRBG is one of the youngest (< 17 Myrs old) and most extensively studied basalt provinces in the world, extending over 163,700 square km with total thickness exceeding 1 km in some places. The morphologies and textures of CRBG basalt columns suggest that in many places flows ~100 m thick cooled at uniform rates, even deep in the flow interior. Such cooling seems to require the presence of water in the column joints since the flow interiors should have cooled much more slowly than the flow margins if conductive cooling dominated. Secondary features, such pillow basalts, likewise suggest the basalt flows were in direct contact with standing water in many places. At the resolution provided by the orbiting HiRISE camera (0.9 m), the Martian basalt columns resemble the CRBG columns in many respects, and so, subject to important caveats, inferences linking the morphologies of the CRBG columns to their thermal histories can be extended in some respects to the Martian columns. In this presentation, we will describe our analysis of the HiRISE images of the Martian columns and what can be reasonably inferred about their thermal histories and the conditions under which they were emplaced. We will also report on a field expedition to the CRBG in eastern Washington State. During that expedition, we surveyed basalt column outcrops on the ground and from the air using Unmanned Aerial

  14. Effect of tropospheric aerosols upon atmospheric infrared cooling rates

    NASA Technical Reports Server (NTRS)

    Harshvardhan, MR.; Cess, R. D.

    1978-01-01

    An investigation has been made of the impact of wind-blown dust particles upon local climate of arid regions. The case of Northwest India is specifically considered, where a dense layer of dust persists for several months during the summer. In order to examine the effect of this dust layer on the infrared radiative flux and cooling rates, a method is presented for calculating the IR flux within a dusty atmosphere which allows the use of gaseous band models and is applicable in the limit of small single scattering albedo and pronounced forward scattering. The participating components of the atmosphere are assumed to be water vapor and spherical quartz particles only. The atmospheric window is partially filled by including the water vapor continuum bands for which empirically obtained transmission functions have been used. It is shown that radically different conclusions may be drawn on dust effects if the continuum absorption is not considered. The radiative transfer model, when applied to a dusty atmosphere, indicates that there is a moderate enhancement in the atmospheric greenhouse and a 10% increase in the mean IR radiative cooling rate, relative to the dust free case, within the lower troposphere. These results have been compared with previous work by other authors in the context of the possibility of dust layers inhibiting local precipitation.

  15. Suprazero Cooling Rate, Rather Than Freezing Rate, Determines Post Thaw Quality Of Rhesus Macaque Sperm

    PubMed Central

    Martorana, Kelly; Klooster, Katie; Meyers, Stuart

    2013-01-01

    Sperm become most sensitive to cold shock when cooled from 37ºC to 5ºC at rates that are too fast or too slow; cold shock increases the susceptibility to oxidative damage due to its influence on reactive oxygen species (ROS) production ([1]. ROS are significant stress factors that are generated during cooling and low temperature storage, and may be a main cause of decreased motility and fertility upon warming. ROS have been shown to change cellular function through the disruption of the sperm plasma membrane and through damage to proteins and DNA. The objective of this study was to determine which cryopreservation rates result in the lowest degree of oxidative damage and greatest sperm quality. In the rhesus model it has not been determined whether suprazero cooling or subzero freezing rates causes a significant amount of ROS damage to sperm. Semen samples were collected from male rhesus macaques, washed, and resuspended in TEST-yolk cryopreservation buffer to 100 x 106 sperm/mL. Sperm were frozen in 0.5mL straws at four different combinations of suprazero and subzero rates. Three different suprazero rates were used between 22ºC and 0ºC: 0.5ºC/min (Slow), 45ºC/min (Medium), and 93ºC/min (Fast). These suprazero rates were used in combination with two different subzero rates for temperatures 0ºC to −110ºC: 42ºC/min (Medium) and 87ºC/min (Fast). The different freezing groups were as follows: Slow-Med (SM), Slow-Fast (SF), Med-Med (MM), and Fast-Fast (FF). Flow cytometry was used to detect lipid peroxidation (LPO), a result of ROS generation. Motility was evaluated using a computer assisted sperm motion analyzer. The MM and FF treated sperm had less viable (P < 0.0001) and motile sperm (P < 0.001) than the SM, SF, or fresh sperm. Sperm exposed to MM and FF treatments demonstrated significantly higher oxidative damage than SM, SF, or fresh sperm (P < 0.05). The SM and SF treated sperm showed decreased motility, membrane integrity, and LPO compared to fresh

  16. Metallographic techniques and microstructures: uranium alloys

    SciTech Connect

    Romig, A.D. Jr.

    1982-08-01

    The techniques used for the metallographic analysis of uranium and its alloys are discussed. Sample preparation and characterization procedures are described for: optical metallography, scanning electron microscopy, electron microprobe analysis, transmission electron microscopy, and scanning transmission electron microscopy. A brief overview of electron optics, electron/sample interactions, signal detectors, and x-ray microanalysis is presented. Typical uranium alloy microstructures observed by these techniques are presented and discussed. The microstructures examined include those produced by the diffusional decomposition of ..gamma..:U-0.75Ti and ..gamma..:U-6Nb, the martensitic decomposition of U-2Mo, U-6Nb, U-0.75Ti and Mulberry, and the aging of quenched U-2Mo.

  17. Effect of cooling rates on the cold hardiness and cryoprotectant profiles of locust eggs.

    PubMed

    Wang, Hong-Sheng; Kang, Le

    2005-10-01

    To examine the relationship between cooling rate and cold hardiness in eggs of the migratory locust, Locusta migratoria, the survival rates and cryoprotectant levels of three embryonic developmental stages were measured at different cooling rates (from 0.05 to 0.8 degrees C min(-1)) in acclimated and non-acclimated eggs. Egg survival rate increased with decreasing cooling rate. The concentration of cryoprotectants (myo-inositol, trehalose, mannitol, glycerol, and sorbitol) increased in non-acclimated eggs, but varied significantly in response to different cooling rates in acclimated eggs. The acclimation process (5 degrees C for 3 days) did not increase eggs resistance to quick cooling ("plunge" cooling and 0.8 degrees C min(-1)). Earlier stage embryos were much more sensitive than later stage embryos to the same cooling rates. Time spent at subzero temperatures also had a strong influence on egg survival. PMID:16115620

  18. Cooling Rates of Humans in Air and in Water: An Experiment

    NASA Astrophysics Data System (ADS)

    Bohren, Craig F.

    2012-12-01

    In a previous article I analyzed in detail the physical factors resulting in greater cooling rates of objects in still water than in still air, emphasizing cooling of the human body. By cooling rate I mean the rate of decrease of core temperature uncompensated by metabolism. I concluded that the "correct ratio for humans is closer to 2 than to 10." To support this assertion I subsequently did experiments, which I report following a digression on hypothermia.

  19. Cooling rates of LL, L and H chondrites and constraints on the duration of peak thermal conditions: Diffusion kinetic modeling and implications for fragmentation of asteroids and impact resetting of petrologic types

    NASA Astrophysics Data System (ADS)

    Ganguly, Jibamitra; Tirone, Massimiliano; Domanik, Kenneth

    2016-11-01

    We have carried out detailed thermometric and cooling history studies of several LL-, L- and H-chondrites of petrologic types 5 and 6. Among the selected samples, the low-temperature cooling of St. Séverin (LL6) has been constrained in an earlier study by thermochronological data to an average rate of ∼2.6 °C/My below 500 °C. However, numerical simulations of the development of Fe-Mg profiles in Opx-Cpx pairs using this cooling rate grossly misfit the measured compositional profiles. Satisfactory simulation of the latter and low temperature thermochronological constraints requires a two-stage cooling model with a cooling rate of ∼50-200 °C/ky from the peak metamorphic temperature of ∼875 °C down to 450 °C, and then transitioning to very slow cooling with an average rate of ∼2.6 °C/My. Similar rapid high temperature cooling rates (200-600 °C/ky) are also required to successfully model the compositional profiles in the Opx-Cpx pairs in the other samples of L5, L6 chondrites. For the H-chondrite samples, the low temperature cooling rates were determined earlier to be 10-20 °C/My by metallographic method. As in St. Séverin, these cooling rates grossly misfit the compositional profiles in the Opx-Cpx pairs. Modeling of these profiles requires very rapid cooling, ∼200-400 °C/ky, from the peak temperatures (∼810-830 °C), transitioning to the metallographic rates at ∼450-500 °C. We interpret the rapid high temperature cooling rates to the exposure of the samples to surface or near surface conditions as a result of fragmentation of the parent body by asteroidal impacts. Using the thermochronological data, the timing of the presumed impact is constrained to be ∼4555-4560 My before present for St. Séverin. We also deduced similar two stage cooling models in earlier studies of H-chondrites and mesosiderites that could be explained, using the available geochronological data, by impact induced fragmentation at around the same time. Diffusion kinetic

  20. Partitioning as a cooling rate indicator. [in chemical analysis of moon rocks

    NASA Technical Reports Server (NTRS)

    Onorato, P. I.; Yinnon, H.; Uhlmann, D. R.; Taylor, L. A.

    1979-01-01

    The paper presents a mathematical model for describing solute partitioning under continuous cooling conditions. It is shown that solute concentration profiles can be calculated for any cooling rate as a function of temperature provided that the appropriate data on diffusion and partitioning are known. As an example, the model is applied to zirconium partitioning between ilmenite and ulvospinel in a number of Apollo 15 Elbow Crater rocks in order to estimate the rates at which they cooled.

  1. New fine structure cooling rate. [electron impact transitions in the ionosphere

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.

    1976-01-01

    One of the dominant electron cooling processes in the ionosphere is caused by electron impact induced fine structure transitions among the ground state levels of atomic oxygen. This fine structure cooling rate is based on theoretical cross sections. Recent advances in the numerical cross section determinations to include polarization effects and more accurate representations of the atomic target result in new lower values. These cross sections are employed in this paper to derive a new fine structure cooling rate which is between 40% and 60% of the currently used rate. A new generalized formula is presented for the cooling rate (from which the fine structure cooling rate is derived), valid for arbitrary mass and temperature difference of the colliding particles and arbitrary inelastic energy difference.

  2. Abnormal correlation between phase transformation and cooling rate for pure metals.

    PubMed

    Han, J J; Wang, C P; Liu, X J; Wang, Y; Liu, Z-K; Zhang, T-Y; Jiang, J Z

    2016-01-01

    This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 10(11)-16.6 × 10(11) K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate. PMID:26939584

  3. Abnormal correlation between phase transformation and cooling rate for pure metals

    PubMed Central

    Han, J. J.; Wang, C. P.; Liu, X. J.; Wang, Y.; Liu, Z.-K.; Zhang, T.-Y.; Jiang, J. Z.

    2016-01-01

    This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 1011–16.6 × 1011 K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate. PMID:26939584

  4. Abnormal correlation between phase transformation and cooling rate for pure metals

    NASA Astrophysics Data System (ADS)

    Han, J. J.; Wang, C. P.; Liu, X. J.; Wang, Y.; Liu, Z.-K.; Zhang, T.-Y.; Jiang, J. Z.

    2016-03-01

    This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 1011–16.6 × 1011 K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate.

  5. The cooling rates of pahoehoe flows: The importance of lava porosity

    NASA Technical Reports Server (NTRS)

    Jones, Alun C.

    1993-01-01

    Many theoretical models have been put forward to account for the cooling history of a lava flow; however, only limited detailed field data exist to validate these models. To accurately model the cooling of lava flows, data are required, not only on the heat loss mechanisms, but also on the surface skin development and the causes of differing cooling rates. This paper argues that the cause of such variations in the cooling rates are attributed, primarily, to the vesicle content and degassing history of the lava.

  6. Soil temperature extrema recovery rates after precipitation cooling

    NASA Technical Reports Server (NTRS)

    Welker, J. E.

    1984-01-01

    From a one dimensional view of temperature alone variations at the Earth's surface manifest themselves in two cyclic patterns of diurnal and annual periods, due principally to the effects of diurnal and seasonal changes in solar heating as well as gains and losses of available moisture. Beside these two well known cyclic patterns, a third cycle has been identified which occurs in values of diurnal maxima and minima soil temperature extrema at 10 cm depth usually over a mesoscale period of roughly 3 to 14 days. This mesoscale period cycle starts with precipitation cooling of soil and is followed by a power curve temperature recovery. The temperature recovery clearly depends on solar heating of the soil with an increased soil moisture content from precipitation combined with evaporation cooling at soil temperatures lowered by precipitation cooling, but is quite regular and universal for vastly different geographical locations, and soil types and structures. The regularity of the power curve recovery allows a predictive model approach over the recovery period. Multivariable linear regression models alloy predictions of both the power of the temperature recovery curve as well as the total temperature recovery amplitude of the mesoscale temperature recovery, from data available one day after the temperature recovery begins.

  7. Transient and residual stresses in dental porcelains as affected by cooling rates.

    PubMed

    Asaoka, K; Tesk, J A

    1989-06-01

    The development of either transient or residual stress in a slab of dental porcelain during cooling was simulated by use of a super-computer. The temperature dependences of the elastic modulus, the thermal expansion coefficient, and the shear viscosity, and the cooling rate dependence of the glass transition temperature, Tg, were considered in this calculation. Internal stress and viscoelastic creep were computed for several cooling rates. Calculated results display stress profiles which agree reasonably well with reported measured profiles in quenched, tempered glasses. The calculated residual surface stress, sigma, could be fit by the following empirical formula, sigma = kl2(q/q0)n, q is the cooling rate, q0 is a reference cooling rate and l is the half-thickness of the porcelain. The method by which residual stress develops is also discussed. This discussion suggests a method for strengthening of the porcelain by the development of high-compressive residual stress on the surface. PMID:2638963

  8. Cooling rate variation in natural volcanic glasses from Tenerife, Canary Islands

    NASA Astrophysics Data System (ADS)

    Wilding, M.; Webb, Sharon; Dingwell, D.; Ablay, Giray; Marti, Joan

    1996-10-01

    Silicate melts form glasses in a variety of geological environments. The relaxation (equilibration) of the frozen glass structure provides a means of investigating the quench rates of natural glasses, and this cooling history provides an important constraint for models of melt dynamics. Phonolite glasses from the central volcanic edifice of Tenerife, Canary Islands indicate a range of five orders of magnitude cooling rate, determined by modeling the relaxation of the structure-dependent property, enthalpy ( H) across the glass transition. The relaxation of enthalpy is determined by heat capacity ( c p = Δ H/Δ T) measurement of natural glass samples by differential scanning calorimetry (DSC). Upon heating, the heat capacity curve in the vicinity of the glass transition has a geometry characteristic of the previous cooling rate. A series of thermal treatments applied to each individual sample results in a set of sample-specific parameters which are used to model the heat capacity curve of the naturally cooled glass. The cooling rate is then derived. The equivalence of shear and enthalpic relaxation enables the relaxation of enthalpy for these volcanic samples to be described by a general term for the evolution of fictive temperature. Quench rates for thirty-one glasses are calculated to be within the range 10°C s 1 to 7°C per day. The cooling rates quoted are linear approximations across the glass transition. Within different volcanic facies cooling rates depend on several factors. The most rapidly cooled glasses occur where samples lose heat by radiation from the surface. Our analyses indicate that in certain environments, a natural annealing process results in slow quench rates. This is interpreted as either a slow initial cooling process or the reheating of a glass to an annealing temperature within the glass transition interval. The latter results in relaxation to a lower temperature structure. Controls on these processes include the initial temperature and

  9. Influence of cooling rate on the precipitation behavior in Ti–Nb–Mo microalloyed steels during continuous cooling and relationship to strength

    SciTech Connect

    Bu, F.Z.; Wang, X.M.; Chen, L.; Yang, S.W.; Shang, C.J.; Misra, R.D.K.

    2015-04-15

    In this study we elucidate carbide precipitation at varied cooling rates in Ti–Nb–Mo microalloyed steels during continuous cooling. The study suggests that increasing the cooling rate prevents precipitate formation in the ferrite phase during continuous cooling after finish rolling at 850 °C. At a lower cooling rate of 0.5 °C/s, the microhardness of ferrite grains exhibited maxima because of high volume fraction of fine carbides. A high density of nanoscale carbides with similar precipitation characteristics, including interphase precipitates, was observed at cooling rates of 0.5 and 1 °C/s, but the carbides were marginally larger and the spacing between them was increased with cooling rate. Additionally, carbide precipitation at a high cooling rate was associated with strain-induced precipitation. Through the analysis of selection area electron diffraction patterns and high-resolution transmission electron microscopy, lattice imaging, the fine spherical-shaped carbides of size ~ 6–10 nm were identified as MC-type carbides of the type (Ti,Nb,Mo)C and NbC. - Highlights: • We model three cooling rates which have indicated different precipitation behaviors. • We find two types of precipitates including NbC and (Ti,Nb,Mo)C based on HRTEM study. • Increasing cooling rate will decrease volume fraction and size of the precipitates. • There is no absence of interphase precipitation when the cooling rate increases to 5 °C/s.

  10. The Dominance of Warming Rate Over Cooling Rate in the Survival of Mouse Oocytes Subjected to a Vitrification Procedure✰

    PubMed Central

    Seki, Shinsuke; Mazur, Peter

    2009-01-01

    The formation of more than trace amounts of ice in cells is lethal. The two contrasting routes to avoiding it are slow equilibrium freezing and vitrification. The cryopreservation of mammalian oocytes by either method continues to be difficult, but there seems a slowly emerging consensus that vitrification procedures are somewhat better for mouse and human oocytes. The approach in these latter procedures is to load cells with high concentrations of glass-inducing solutes and cool them at rates high enough to induce the glassy state. Several devices have been developed to achieve very high cooling rates. Our study has been concerned with the relative influences of warming rate and cooling rate on the survival of mouse oocytes subjected to a vitrification procedure. Oocytes suspended in an ethylene glycol-acetamide-Ficoll-sucrose solution were cooled to −196°C at rates ranging from 37°C/min to 1827°C/min between 20°C and −120°C, and for each cooling rate, warmed at rates ranging from 139°C/min to 2950°C/min between −70°C and −35°C. The results are unambiguous. If the samples were warmed at the highest rate, survivals were >80% over cooling rates of 187°C/min to 1827°C/min. If the samples were warmed at the lowest rate, survivals were near 0% regardless of the cooling rate. We interpret the lethality of slow warming to be a consequence of it allowing time for the growth of small intracellular ice crystals by recrystallization. PMID:19427303

  11. Influence of cooling rate on interlaminar fracture properties of unidirectional commingled CF/PEEK composites

    NASA Astrophysics Data System (ADS)

    Beehag, Andrew; Ye, Lin

    1995-05-01

    The influence of cooling rates on the mechanical property profile (transverse flexure properties and modes-I and -II interlaminar fracture toughness) has been investigated for unidirectional commingled CF/PEEK composites. A laboratory hot press with a steel mould was used to process the composites at 400°C for 60 min, at an applied pressure of 1 MPa. Cooling rates from fast (quenching in oil) to slow (hot press cooling) were achieved at ambient pressure. The results indicate that different matrix morphology was found at different cooling conditions, although deconsolidation occurred in the CF/PEEK composites during cooling. When the cooling rate was shifted from slow to fast, consolidation quality of the CF/PEEK composites was improved. The resulting effect of the consolidation quality and cooling rates on the mechanical property profile of commingled CF/PEEK composites is presented. It was found that the effect of the cooling rate on the mechanical property profile of the commingled CF/PEEK composites could not be isolated from the consolidation quality.

  12. Induction of rapid cold hardening by cooling at ecologically relevant rates in Drosophila melanogaster.

    PubMed

    Kelty, J D.; Lee, R E.

    1999-08-01

    Over a decade ago it was hypothesized that the rapid cold hardening process allows an organism's overall cold tolerance to track changes in environmental temperature, as would occur in nature during diurnal thermal cycles. Although a number of studies have since focused on characterizing the rapid cold hardening process and on elucidating the physiological mechanisms upon which it is based, the ecological relevance of this phenomenon has received little attention. We present evidence that in Drosophila melanogaster rapid cold hardening can be induced during cooling at rates which occur naturally, and that the protection afforded in such a manner benefits the organism at ecologically relevant temperatures. Drosophila melanogaster cooled at natural rates (0.05 and 0.1 degrees C min(-1)) exhibited significantly higher survival after one hour of exposure to -7 and -8 degrees C than did those directly transferred to these temperatures or those cooled at 0.5, or 1.0 degrees C min(-1). Protection accrued throughout the cooling process (e.g., flies cooled to 0 degrees C were more cold tolerant than those cooled to 11 degrees C). Whereas D. melanogaster cooled at 1.0 degrees C min(-1) had a critical thermal minimum (i.e., the temperature at which torpor occurred) of 6.5+/-0.6 degrees C, those cooled at an ecologically relevant rate of 0.1 degrees C min(-1) had a significantly lower value of 3.9+/-0.9 degrees C. PMID:12770302

  13. Effect of the cooling rate on the phase composition and structure of copper matte converting slags

    NASA Astrophysics Data System (ADS)

    Selivanov, E. N.; Gulyaeva, R. I.; Udoeva, L. Yu.; Belyaev, V. V.; Pankratov, A. A.

    2009-08-01

    The effect of the cooling rate on the phase composition and microstructure of copper matte converting slags is studied by X-ray diffraction, combined thermogravimetry and calorimetry, mineragraphy, and electron-probe microanalysis. The compositions of oxide and sulfide phases are determined, and the forms of nonferrous metals in slags cooled at a rate of 0.3 and 900°C/s are revealed. At high cooling rates of the slags, iron silicate glass is shown to form apart from sulfide phases. Repeated heating of the slags leads to the development of devitrification, “cold” crystallization, and melting. A decrease in the cooling rate favors an increase in the grain sizes in oxides (magnetite, iron silicates) and sulfides (bornite-, sphalerite, and galena-based solid solutions).

  14. Effect of Cooling Rate on the Dendrite Coherency Point During Solidification of Al2024 Alloy

    NASA Astrophysics Data System (ADS)

    Ghoncheh, M. H.; Shabestari, S. G.

    2015-03-01

    Most research related to dendrite coherency point (DCP) has been done on cast aluminum alloys and at a low cooling rate condition. In this research, the DCP of a wrought aluminum alloy is calculated in the range of high cooling rates used in the direct-chill casting process. The two-thermocouple thermal analysis technique was used to determine the DCP of Al2024 alloy. The aim of this work is to investigate the effect of different cooling rates on the dendrite coherency characteristics of Al2024. The cooling rates used in the present study range from 0.4 to 17.5 °C s-1. Also, the effect of 1.2 wt pct Al-5Ti-1B grain refiner on the DCP was studied. To calculate the solid fraction at dendrite coherency, solid fraction versus time is plotted based on Newtonian technique. The results show that by increasing the cooling rate, both time and temperature of dendrite coherency are decreased. Also, by adding the Al-5Ti-1B master alloy, dendrite coherency temperature is reduced and dendrite impingement is postponed. To reduce casting defects occurring during equiaxed solidification, e.g., macrosegregation, porosities, and hot tearing, these two operations which lead to postpone the transition from mass to inter-dendritic feeding, or dendrite coherency, can be useful. By increasing the cooling rate, solid fraction at dendrite coherency increases initially and then decreases at higher cooling rates. Presence of grain refiner leads to increasing of solid fraction at DCP. Thus, by delaying the dendrite coherency and increasing the solid fraction at DCP, semi-solid forming can be performed on parts with higher solid fraction and less shrinkage. Microstructural evaluation was carried out to present the correlation between the cooling rate and solid fraction in 2024 aluminum alloy.

  15. Apparent Cooling Rate of 7°C per Hour in an Avalanche Victim.

    PubMed

    Ströhle, Mathias; Putzer, Gabriel; Procter, Emily; Paal, Peter

    2015-12-01

    Avalanche victims can become hypothermic within 35 minutes of snow burial. However, reported cooling rates for avalanche victims are highly variable and it is poorly understood how much cooling is influenced by general factors (body composition, clothing, ambient conditions, duration of burial, and metabolism), unknown inter-individual factors or other phenomena (e.g., afterdrop). We report an apparent cooling rate of ∼7°C in ∼60 minutes in a healthy backcountry skier who was rewarmed with forced air and warm fluids and was discharged after 2 weeks without neurological sequelae.

  16. Apparent Cooling Rate of 7°C per Hour in an Avalanche Victim.

    PubMed

    Ströhle, Mathias; Putzer, Gabriel; Procter, Emily; Paal, Peter

    2015-12-01

    Avalanche victims can become hypothermic within 35 minutes of snow burial. However, reported cooling rates for avalanche victims are highly variable and it is poorly understood how much cooling is influenced by general factors (body composition, clothing, ambient conditions, duration of burial, and metabolism), unknown inter-individual factors or other phenomena (e.g., afterdrop). We report an apparent cooling rate of ∼7°C in ∼60 minutes in a healthy backcountry skier who was rewarmed with forced air and warm fluids and was discharged after 2 weeks without neurological sequelae. PMID:26217979

  17. Effect of Cooling Rate on Phosphorus Removal During Al-Si Solvent Refining

    NASA Astrophysics Data System (ADS)

    Li, Yanlei; Ban, Boyuan; Li, Jingwei; Zhang, Taotao; Bai, Xiaolong; Chen, Jian; Dai, Songyuan

    2015-04-01

    The effect of cooling rate on phosphorus removal during Al-Si solvent refining is studied during solar grade silicon purification. It is found that the phosphorus removal rate is controlled by kinetic factors. When the cooling rate decreases, the phosphorus removal rate increases. A concept of apparent segregation coefficient of phosphorus is introduced to characterize the phosphorous removal ability. It increases with the decrease in the average solidification temperature between 910.5 K and 1050.5 K (637.5 °C and 777.5 °C).

  18. The Influence of Cooling Rates on Paleointensity of Volcanic Glasses: an Experimental Approach on Synthetic Glass

    NASA Astrophysics Data System (ADS)

    von Aulock, F. W.; Ferk, A.; Leonhardt, R.; Hess, K.-U.; Dingwell, D. B.

    2009-04-01

    The suitability of volcanic glass for paleointensity determinations has been proposed in many studies throughout the last years. Besides the mainly single domain magnetic remanence carriers and the pristine character of the volcanic glass, this was also reasoned by the possibility to correct paleointensity data for cooling rate dependency using relaxation geospeedometry. This method gives the cooling rate of a glass at the glass transition interval which marks the change of a ductile supercooled liquid to a brittle glass. In this study the cooling rate correction as carried out for example by Leonhardt et al. 2006 is tested on synthetic volcanic glass. In order to obtain a stable multicomponent glass with ideal magnetic properties, a natural phonolithic glass from Tenerife (Spain) was melted to avoid heterogeneity and degassing. Further it was tempered for 5 hours at 900 °C to yield a sufficient concentration of magnetic remanence carriers. To exclude nucleation or crystallisation 7 samples were then heated to about 50 °C above the glass transition temperature at around 720 °C and quenched at different rates from 0.1 to 15 K/min. After carrying out a paleointensity experiment using a modified Thellier method, which incorporated alteration, additivity and tail checks, the dependence of the thermoremance on cooling rate was investigated. Using the original cooling rates we corrected the data and obtained paleointensities of around 46 T, which is a good approximation of the ambient field of 48 T. Taking into account that the uncorrected mean paleointensity is about 57 T, this suggests that cooling rate correction is not only working, but also a necessary tool to yield the true field value. R. Leonhardt , J. Matzka, A.R.L. Nichols , D.B. Dingwell Cooling rate correction of paleointensity determination for volcanic glasses by relaxation geospeedometry; Earth and Planetary Science Letters 243 (2006) 282-292

  19. Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yi, D.; Mironov, S.; Sato, Y. S.; Kokawa, H.

    2016-06-01

    In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20-62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 Tm (Tm being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.

  20. Is it reasonable to assume a uniformly distributed cooling-rate along the microslide of a directional solidification stage?

    PubMed

    Rabin

    2000-10-01

    It is commonly assumed that the cooling-rate along the microslide of a directional solidification stage is uniformly distributed, an assumption which is typically applied in low cooling-rates studies. A new directional solidification stage has recently been presented, which is specified to achieve high cooling-rates of up to 1.8 x 104 degrees C min-1, where cooling-rates are still assumed to be uniformly distributed. The current study presents a closed-form solution to the temperature distribution and to the cooling-rate in the microslide. Thermal analysis shows that the cooling-rate is by no means uniformly distributed and can vary by several hundred percent along the microslide in some cases. Therefore, the mathematical solution presented in this study is essential for experimental planning of high cooling-rate experiments.

  1. Radiative forcing of the stratosphere of Jupiter, Part I: Atmospheric cooling rates from Voyager to Cassini

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Nixon, C. A.; Shia, R. L.; West, R. A.; Irwin, P. G. J.; Yelle, R. V.; Allen, M. A.; Yung, Y. L.

    2013-11-01

    We developed a line-by-line heating and cooling rate model for the stratosphere of Jupiter, based on two complete sets of global maps of temperature, C2H2 and C2H6, retrieved from the Cassini and Voyager observations in the latitude and vertical plane, with a careful error analysis. The non-LTE effect is found unimportant on the thermal cooling rate below the 0.01 mbar pressure level. The most important coolants are molecular hydrogen between 10 and 100 mbar, and hydrocarbons, including ethane (C2H6), acetylene (C2H2) and methane (CH4), in the region above. The two-dimensional cooling rate maps are influenced primarily by the temperature structure, and also by the meridional distributions of C2H2 and C2H6. The temperature anomalies at the 1 mbar pressure level in the Cassini data and the strong C2H6 latitudinal contrast in the Voyager epoch are the two most prominent features influencing the cooling rate patterns, with the effect from the 'quasi-quadrennial oscillation (QQO)' thermal structures at ~20 mbar. The globally averaged CH4 heating and cooling rates are not balanced, clearly in the lower stratosphere under 10 mbar, and possibly in the upper stratosphere above the 1 mbar pressure level. Possible heating sources from the gravity wave breaking and aerosols are discussed. The radiative relaxation timescale in the lower stratosphere implies that the temperature profile might not be purely radiatively controlled.

  2. Cooling rate dependence of solidification for liquid aluminium: a large-scale molecular dynamics simulation study.

    PubMed

    Hou, Z Y; Dong, K J; Tian, Z A; Liu, R S; Wang, Z; Wang, J G

    2016-06-29

    The effect of the cooling rate on the solidification process of liquid aluminium is studied using a large-scale molecular dynamics method. It is found that there are various types of short-range order (SRO) structures in the liquid, among which the icosahedral (ICO)-like structures are dominant. These SRO structures are in dynamic fluctuation and transform each other. The effect of the cooling rate on the microstructure is very weak at high temperatures and in supercooled liquids, and it appears only below the liquid-solid transition temperature. Fast cooling rates favour the formation of amorphous structures with ICO-like features, while slow cooling rates favour the formation of FCC crystalline structures. Furthermore, FCC and HCP structures can coexist in crystalline structures. It is also found that nanocrystalline aluminium can be achieved at appropriate cooling rates, and its formation mechanism is thoroughly investigated by tracing the evolution of nanoclusters. The arrangement of FCC and HCP atoms in the nanograins displays various twinned structures as observed using visualization analysis, which is different from the layering or phase separation structures observed in the solidification of Lennard-Jones fluids and some metal liquids. PMID:27302145

  3. Building a continuous cooling transformation diagram of {beta}-CEZ alloy by metallography and electrical resistivity measurements

    SciTech Connect

    Angelier, C.; Bein, S.; Bechet, J.

    1997-12-01

    The phase transformations of Ti-5Al-2SN-4Zr-4Mo-2Cr-1Fe ({beta}-CEZ) have been studied during continuous cooling after {beta}-solution treatment. For this purpose, electrical resistivity measurements and metallographical examinations have been carried out, and the continuous cooling transformation (CCT) diagram of {beta}-CEZ alloy has been plotted. The different kinds of {beta}-phase decomposition schemes in {beta}-CEZ alloy during continuous cooling have been investigated in detail. Two main morphological features of the {alpha}/{beta} structure are involved, depending on the cooling rate: the basket-weave and the colony structures are observed for high and low cooling rates, respectively. For the intermediate cooling rates, the two morphologies coexist. Finally, a generalized scheme of the {beta} {yields} {beta} + {alpha} transformation sequences during continuous cooling is presented.

  4. Theoretical analysis of specimen cooling rate during impact freezing and liquid-jet freezing of freeze-etch specimens.

    PubMed

    Kopstad, G; Elgsaeter, A

    1982-11-01

    We have carried out a theoretical analysis of specimen cooling rate under ideal conditions during impact freezing and liquid-jet freezing. The analysis shows that use of liquid helium instead of liquid nitrogen as cooling medium during impact freezing results in an increase in a specimen cooling rate of no more than 30-40%. We have further shown that when both impact freezing and liquid-jet freezing are conducted at liquid nitrogen temperature, the two methods give approximately the same specimen cooling rate under ideal conditions except for a thin outer layer of the specimen. In this region impact freezing yields the highest cooling rate. PMID:7171712

  5. The effects of cooling rates and type of freezing extenders on cryosurvival of rat sperm

    PubMed Central

    Varisli, Omer; Scott, Hollie; Agca, Cansu; Agca, Yuksel

    2013-01-01

    Cryopreservation of rat sperm is very challenging due to its sensitivity to various stress factors. The objective of this study was to determine the optimal cooling rate and extender for epididymal sperm of outbred Sprague Dawley (SD) and inbred Fischer 344 (F344) rat strains. The epididymal sperm from 10–12 weeks old sexually mature SD and F344 strains were suspended in five different freezing extenders, namely HEPES buffered Tyrode’s lactate (TL-HEPES), modified Kreb’s Ringer bicarbonate (mKRB), 3% dehydrated skim milk (SM), Salamon’s Tris-citrate (TRIS), and tes/tris (TES). All extenders contained 20% egg yolk, 0.75% Equex Paste and 0.1 M raffinose or 0.1 M sucrose. The sperm samples in each extender were cooled to 4°C and held for 45 min for equilibration before freezing. The equilibrated sperm samples in each extender were placed onto a shallow quartz dish inserted into Linkam Cryostage (BCS 196). The samples were then cooled to a final temperature of −150 °C by using various cooling rates (10, 40, 70, and 100 °C/min). For thawing, the quartz dish containing the sperm samples were rapidly removed from the Linkam cryo-stage and placed on a 37 °C slide warmer and held for 1 min before motility analysis. Sperm membrane and acrosomal integrity and mitochondrial membrane potential (MMP) were assessed by SYBR-14/Propidium iodide, Alexa Fluor-488-PNA conjugate and JC-1, respectively. The total motility, acrosomal integrity, membrane integrity and MMP values were compared among cooling rates and extenders. Both cooling rate and type of extender had significant effect on cryosurvival (P<0.05). Sperm motility increased as cooling rate was increased for both strains (P<0.05). Highest cryosurvival was achieved when 100 °C/min cooling rate was used in combination with TES extender containing 20% egg yolk, 0.75% Equex paste and either 0.1 M sucrose or raffinose (P < 0.05). This study showed that TES extender containing 0.1 M raffinose or sucrose with 70

  6. Apparent I-Xe Cooling Rates of Chondrules Compared with Silicates from the Colomera Iron Meteorite

    NASA Technical Reports Server (NTRS)

    Hohenberg, C. M.; Meshik, A. P.; Pravdivseva, O. V.

    2004-01-01

    In I-Xe dating, a regular pattern of increasing Xe-129/128Xe-128 ratio with increasing extraction temperature is often observed. If one makes the crude assumption that the temperatures at which the Xe is extracted in the laboratory is approximately the same as the temperature at which those sites closed 4.6 Ga ago, a (zeroth order) model cooling rate can be found. In order to test and refine this model we can apply the cooling theory of Dodson to those extraction steps approaching the I-Xe isochrons. Using an Arrhenius plot for these temperature fractions, and assuming that an only single phase is involved, the effective diffusion parameters can be estimated (frequency factor and activation energy). From the apparent (zeroth order) cooling rate, the closure temperature can be estimated from the Dodson equation. This model closure temperature can then be compared with the actual laboratory temperature at which the isochron begins. The ratio of the closure temperature and the temperature corresponding to the start of the isochron provides the ratio of the two temperature scales, incorporation and extraction. The actual cooling rate is then given by the apparent (zeroth order) cooling rate times the temperature scale factor. Figure 1 shows Arrhenius plots for I-Xe data

  7. The influence of cooling rate on the microstructure of stainless steel alloys

    SciTech Connect

    Elmer, J.W.

    1988-09-01

    The emergence of high energy density welding, laser surface modification and rapid solidification as commonly used metallurgical processing techniques has greatly increased the range of cooling rates that can be accessed during the solidification of metals and alloys. The microstructures which develop during these rapid cooling conditions may be significantly different from those which develop during low cooling rate conditions as the result of access to new metastable phases with the additional kinetic limitations that accompany rapid solidification. This investigation explores the influence of cooling rate on a series of seven ternary alloys which span the line of two-fold saturation in the Fe-Ni-Cr system. High speed electron beam surface melting was used to resolidify these alloys at scan speeds up to 5 m/s. The resulting cooling rates were estimated from dendrite arm spacing measurements and were confirmed by heat flow modeling to vary from 7 /times/ 10/sup 0/ /degree/C/s to 8 /times/ 10/sup 6/ /degree/C/s. The microstructures that developed from each solidification condition were examined using optical metallography, electron microprobe analysis, scanning electron microscopy and a vibrating sample magnetometer. These results were used to create diagrams to predict the primary mode of solidification, the ferrite content and the complex microstructural morphologies which develop as a function of interface velocity and composition. 158 refs., 90 figs., 45 tabs.

  8. Evaporation Loss of Light Elements as a Function of Cooling Rate: Logarithmic Law

    NASA Technical Reports Server (NTRS)

    Xiong, Yong-Liang; Hewins, Roger H.

    2003-01-01

    Knowledge about the evaporation loss of light elements is important to our understanding of chondrule formation processes. The evaporative loss of light elements (such as B and Li) as a function of cooling rate is of special interest because recent investigations of the distribution of Li, Be and B in meteoritic chondrules have revealed that Li varies by 25 times, and B and Be varies by about 10 times. Therefore, if we can extrapolate and interpolate with confidence the evaporation loss of B and Li (and other light elements such as K, Na) at a wide range of cooling rates of interest based upon limited experimental data, we would be able to assess the full range of scenarios relating to chondrule formation processes. Here, we propose that evaporation loss of light elements as a function of cooling rate should obey the logarithmic law.

  9. Investigations on the effect of different cooling rates on the stability of amorphous indomethacin.

    PubMed

    Karmwar, P; Boetker, J P; Graeser, K A; Strachan, C J; Rantanen, J; Rades, T

    2011-10-01

    Amorphous forms of indomethacin have previously been prepared using various preparation techniques and it could be demonstrated that the way the material was prepared influenced the physicochemical properties of the amorphous form of the drug. The aim of this study was to use one preparation technique (transformation via the melt) to prepare amorphous indomethacin and to investigate the influence of the cooling rate (as a processing parameter) on the physical stability of the resulting amorphous form. The amorphous materials obtained were analysed for their structural characteristics using Raman spectroscopy in combination with multivariate data analysis. The onset of crystallisation was determined as an indicator of the physical stability of the materials using differential scanning calorimetry (DSC) and polarising light microscopy. The Johnson-Mehl-Avrami (JMA) model and Sestak-Berggren (SB) model were used in this study to describe the non-isothermal crystallisation behaviour. All differently cooled samples were completely X-ray amorphous. Principal component analysis of the Raman spectra of the various amorphous forms revealed that the samples clustered in the scores plot according to the cooling rate, suggesting structural differences between the differently cooled samples. The minimum cooling rate required to obtain amorphous indomethacin was 1.2 K min(-1), as assessed from the time-temperature-transformation (TTT) diagram. The physical stability of the samples was found to increase as a function of cooling rate in the order of 30 K min(-1) > 20 K min(-1) > 10 K min(-1) > 5 K min(-1) > 3 K min(-1) ≈ 1.2 K min(-1) and was in agreement with calculated descriptors for the glass forming ability (GFA), including the reduced glass transition temperature (T(rg)) and the reduced temperature (T(red)). The JMA model could not be applied to describe the crystallisation process for the differently cooled melts of indomethacin in this study. The kinetic exponent M from

  10. Microwave continuum measurements and estimates of mass loss rates for cool giants and supergiants

    NASA Technical Reports Server (NTRS)

    Drake, S. A.; Linsky, J. L.

    1986-01-01

    Attention is given to the results of a sensitive, 6-cm radio continuum survey conducted with the NRAO VLA of 39 of the nearest single cool giants and supergiants of G0-M5 spectral types; the survey was conducted in order to obtain accurate measurements of the mass loss rates of ionized gas for a representative sample of such stars, in order to furnish constraints for, and a better understanding of, the total mass loss rates. The inferred angular diameters for the cool giant sources are noted to be twice as large as photospheric angular diameters, implying that these stars are surrounded by extended chromospheres containing warm partially ionized gas.

  11. A flight-rated liquid-cooled garment for use within a full-pressure suit

    NASA Technical Reports Server (NTRS)

    Carpenter, R.; Winter, W. R.

    1972-01-01

    A flight rated liquid cooled garment system for use inside a full pressure suit has been designed, fabricated, and tested. High temperature tests with this system have indicated that heat is absorbed at a rate decreasing from 224 kg-cal/hr to 143 kg-cal/hr over a 40-min period. The first 30 min are very comfortable; thereafter a gradual heat load builds that results in mild sweating at the end of the 40-min period. In flight tests during hot weather when this cooling system was worn under a regulation flight suit, the pilot reported that temperatures were comfortable and that the garment prevented sweating.

  12. Probing polymer crystallization at processing-relevant cooling rates with synchrotron radiation

    SciTech Connect

    Cavallo, Dario; Portale, Giuseppe; Androsch, René

    2015-12-17

    Processing of polymeric materials to produce any kind of goods, from films to complex objects, involves application of flow fields on the polymer melt, accompanied or followed by its rapid cooling. Typically, polymers solidify at cooling rates which span over a wide range, from a few to hundreds of °C/s. A novel method to probe polymer crystallization at processing-relevant cooling rates is proposed. Using a custom-built quenching device, thin polymer films are ballistically cooled from the melt at rates between approximately 10 and 200 °C/s. Thanks to highly brilliant synchrotron radiation and to state-of-the-art X-ray detectors, the crystallization process is followed in real-time, recording about 20 wide angle X-ray diffraction patterns per second while monitoring the instantaneous sample temperature. The method is applied to a series of industrially relevant polymers, such as isotactic polypropylene, its copolymers and virgin and nucleated polyamide-6. Their crystallization behaviour during rapid cooling is discussed, with particular attention to the occurrence of polymorphism, which deeply impact material’s properties.

  13. Modeling Thermospheric Energetics: Implications of Cooling Rate Measurements by TIMED/SABER

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; Qian, L.; Mlynczak, M. G.

    2012-12-01

    Infrared radiation from the lower thermosphere has a significant effect on thermospheric temperature throughout its altitude range. Energy deposited in the upper thermosphere is conducted downward to altitudes where collisional processes with heterogeneous molecules are effective in exciting radiative transitions. Thus, exospheric temperature is strongly influenced by the infrared cooling rates. Measurements from the SABER instrument on the TIMED satellite have provided the global distribution and temporal variation of the two most important cooling rates, from the 15-micron band of carbon dioxide, and the 5.3-micron band of nitric oxide, both excited in the thermosphere primarily by collisions with atomic oxygen [e.g., Mlynczak et al., JGR, 2010]. Because these measurements are of the cooling rate itself, they are nearly independent of assumptions concerning carbon dioxide or nitric oxide density, atomic oxygen density, temperature, and rate coefficients, and so provide strong constraints on global models. Simulations using the NCAR Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM) have obtained reasonable agreement with global nitric oxide cooling rates, on daily and solar-cycle time scales alike [c.f., Qian et al., JGR, 2010; Solomon et al., JGR, 2012]. This may be somewhat surprising, or serendipitous, considering the complexity of the production and chemistry of thermospheric nitric oxide, but is a hopeful indication of the model's ability to describe thermospheric temperature structure and variability. However, initial model simulations of 15-micron carbon dioxide emission have been significantly lower than the SABER measurements. This indicates that there may be issues with the carbon dioxide densities, with the atomic oxygen density, or with the rate coefficient for their interaction. Simply increasing any of these to bring the cooling rate into agreement with SABER measurements will have the additional effect of

  14. Temperatures and cooling rates recorded in REE in coexisting pyroxenes in ophiolitic and abyssal peridotites

    NASA Astrophysics Data System (ADS)

    Dygert, Nick; Liang, Yan

    2015-06-01

    Mantle peridotites from ophiolites are commonly interpreted as having mid-ocean ridge (MOR) or supra-subduction zone (SSZ) affinity. Recently, an REE-in-two-pyroxene thermometer was developed (Liang et al., 2013) that has higher closure temperatures (designated as TREE) than major element based two-pyroxene thermometers for mafic and ultramafic rocks that experienced cooling. The REE-in-two-pyroxene thermometer has the potential to extract meaningful cooling rates from ophiolitic peridotites and thus shed new light on the thermal history of the different tectonic regimes. We calculated TREE for available literature data from abyssal peridotites, subcontinental (SC) peridotites, and ophiolites around the world (Alps, Coast Range, Corsica, New Caledonia, Oman, Othris, Puerto Rico, Russia, and Turkey), and augmented the data with new measurements for peridotites from the Trinity and Josephine ophiolites and the Mariana trench. TREE are compared to major element based thermometers, including the two-pyroxene thermometer of Brey and Köhler (1990) (TBKN). Samples with SC affinity have TREE and TBKN in good agreement. Samples with MOR and SSZ affinity have near-solidus TREE but TBKN hundreds of degrees lower. Closure temperatures for REE and Fe-Mg in pyroxenes were calculated to compare cooling rates among abyssal peridotites, MOR ophiolites, and SSZ ophiolites. Abyssal peridotites appear to cool more rapidly than peridotites from most ophiolites. On average, SSZ ophiolites have lower closure temperatures than abyssal peridotites and many ophiolites with MOR affinity. We propose that these lower temperatures can be attributed to the residence time in the cooling oceanic lithosphere prior to obduction. MOR ophiolites define a continuum spanning cooling rates from SSZ ophiolites to abyssal peridotites. Consistent high closure temperatures for abyssal peridotites and the Oman and Corsica ophiolites suggests hydrothermal circulation and/or rapid cooling events (e.g., normal

  15. Pāhoehoe flow cooling, discharge, and coverage rates from thermal image chronometry

    USGS Publications Warehouse

    Dehn, Jonathan; Hamilton, Christopher M.; Harris, A. J. L.; Herd, Richard A.; James, M.R.; Lodato, Luigi; Steffke, Andrea

    2007-01-01

    Theoretically- and empirically-derived cooling rates for active pāhoehoe lava flows show that surface cooling is controlled by conductive heat loss through a crust that is thickening with the square root of time. The model is based on a linear relationship that links log(time) with surface cooling. This predictable cooling behavior can be used assess the age of recently emplaced sheet flows from their surface temperatures. Using a single thermal image, or image mosaic, this allows quantification of the variation in areal coverage rates and lava discharge rates over 48 hour periods prior to image capture. For pāhoehoe sheet flow at Kīlauea (Hawai`i) this gives coverage rates of 1–5 m2/min at discharge rates of 0.01–0.05 m3/s, increasing to ∼40 m2/min at 0.4–0.5 m3/s. Our thermal chronometry approach represents a quick and easy method of tracking flow advance over a three-day period using a single, thermal snap-shot.

  16. Measurement of cooling and warming rates in vitrification-based plant cryopreservation protocols.

    PubMed

    Teixeira, Aline S; González-Benito, M Elena; Molina-García, Antonio D

    2014-01-01

    Cryopreservation protocols include the use of additives and pretreatments aimed to reduce the probability of ice nucleation at all temperatures, mainly through micro-viscosity increase. Still, there is a risk of ice formation in the temperature region comprised between the equilibrium freezing (Tf ) and the glass transition (TG ) temperatures. Consequently, fast cooling and warming, especially in this region, is a must to avoid ice-derived damage. Vitrification and droplet-vitrification techniques, frequently used cryopreservation protocols based in fast cooling, were studied, alongside with the corresponding warming procedures. A very fast data acquisition system, able to read very low temperatures, down to that of liquid nitrogen, was employed. Cooling rates, measured between -20°C and -120°C, ranged from ca. 5°C s(-1) to 400°C s(-1) , while warming rates spanned from ca. 2°C s(-1) to 280°C s(-1) , for the different protocols and conditions studied. A wider measuring window (0°C to -150°C) produced lower rates for all cases. The cooling and warming rates were also related to the survival observed after the different procedures. Those protocols with the faster rates yielded the highest survival percentages. PMID:24933257

  17. Measurement of cooling and warming rates in vitrification-based plant cryopreservation protocols.

    PubMed

    Teixeira, Aline S; González-Benito, M Elena; Molina-García, Antonio D

    2014-01-01

    Cryopreservation protocols include the use of additives and pretreatments aimed to reduce the probability of ice nucleation at all temperatures, mainly through micro-viscosity increase. Still, there is a risk of ice formation in the temperature region comprised between the equilibrium freezing (Tf ) and the glass transition (TG ) temperatures. Consequently, fast cooling and warming, especially in this region, is a must to avoid ice-derived damage. Vitrification and droplet-vitrification techniques, frequently used cryopreservation protocols based in fast cooling, were studied, alongside with the corresponding warming procedures. A very fast data acquisition system, able to read very low temperatures, down to that of liquid nitrogen, was employed. Cooling rates, measured between -20°C and -120°C, ranged from ca. 5°C s(-1) to 400°C s(-1) , while warming rates spanned from ca. 2°C s(-1) to 280°C s(-1) , for the different protocols and conditions studied. A wider measuring window (0°C to -150°C) produced lower rates for all cases. The cooling and warming rates were also related to the survival observed after the different procedures. Those protocols with the faster rates yielded the highest survival percentages.

  18. Metallographic autopsies of full-scale ITER prototype cable-in-conduit conductors after full testing in SULTAN: 1. The mechanical role of copper strands in a CICC

    NASA Astrophysics Data System (ADS)

    Sanabria, Carlos; Lee, Peter J.; Starch, William; Blum, Timothy; Devred, Arnaud; Jewell, Matthew C.; Pong, Ian; Martovetsky, Nicolai; Larbalestier, David C.

    2015-08-01

    Cables made with Nb3Sn-based superconductor strands will provide the 13 T maximum peak magnetic field of the ITER central solenoid (CS) coils and they must survive up to 60 000 electromagnetic cycles. Accordingly, prototype designs of CS cable-in-conduit-conductors (CICC) were electromagnetically tested over multiple magnetic field cycles and warm-up-cool-down scenarios in the SULTAN facility at CRPP. We report here a post-mortem metallographic analysis of two CS CICC prototypes which exhibited some rate of irreversible performance degradation during cycling. The standard ITER CS CICC cable design uses a combination of superconducting and Cu strands, and because the Lorentz force on the strand is proportional to the transport current in the strand, removing the copper strands (while increasing the Cu:SC ratio of the superconducting strands) was proposed as one way of reducing the strand load. In this study we compare the two alternative CICCs, with and without Cu strands, keeping in mind that the degradation after the SULTAN test was lower for the CICC without Cu strands. The post-mortem metallographic evaluation revealed that the overall strand transverse movement was 20% lower in the CICC without Cu strands and that the tensile filament fractures found were less, both indications of an overall reduction in high tensile strain regions. It was interesting to see that the Cu strands in the mixed cable design (with higher degradation) helped reduce the contact stresses on the high pressure side of the CICC, but in either case, the strain reduction mechanisms were not enough to suppress cyclic degradation. Advantages and disadvantages of each conductor design are discussed here aimed to understand the sources of the degradation.

  19. Metallographic autopsies of full-scale ITER prototype cable-in-conduit conductors after full testing in SULTAN: 1. The mechanical role of copper strands in a CICC

    DOE PAGES

    Sanabria, Carlos; Lee, Peter J.; Starch, William; Blum, Timothy; Devred, Arnaud; Jewell, Matthew C.; Pong, Ian; Martovetsky, Nicolai; Larbalestier, David C.

    2015-06-22

    Cables made with Nb3Sn-based superconductor strands will provide the 13 T maximum peak magnetic field of the ITER Central Solenoid (CS) coils and they must survive up to 60,000 electromagnetic cycles. Accordingly, prototype designs of CS cable-in-conduit-conductors (CICC) were electromagnetically tested over multiple magnetic field cycles and warm-up-cool-down scenarios in the SULTAN facility at CRPP. We report here a post mortem metallographic analysis of two CS CICC prototypes which exhibited some rate of irreversible performance degradation during cycling. The standard ITER CS CICC cable design uses a combination of superconducting and Cu strands, and because the Lorentz force on themore » strand is proportional to the transport current in the strand, removing the copper strands (while increasing the Cu:SC ratio of the superconducting strands) was proposed as one way of reducing the strand load. In this study we compare the two alternative CICCs, with and without Cu strands, keeping in mind that the degradation after SULTAN test was lower for the CICC without Cu strands. The post mortem metallographic evaluation revealed that the overall strand transverse movement was 20% lower in the CICC without Cu strands and that the tensile filament fractures found were less, both indications of an overall reduction in high tensile strain regions. Furthermore, it was interesting to see that the Cu strands in the mixed cable design (with higher degradation) helped reduce the contact stresses on the high pressure side of the CICC, but in either case, the strain reduction mechanisms were not enough to suppress cyclic degradation. Advantages and disadvantages of each conductor design are discussed here aimed to understand the sources of the degradation.« less

  20. Metallographic autopsies of full-scale ITER prototype cable-in-conduit conductors after full testing in SULTAN: 1. The mechanical role of copper strands in a CICC

    SciTech Connect

    Sanabria, Carlos; Lee, Peter J.; Starch, William; Blum, Timothy; Devred, Arnaud; Jewell, Matthew C.; Pong, Ian; Martovetsky, Nicolai; Larbalestier, David C.

    2015-06-22

    Cables made with Nb3Sn-based superconductor strands will provide the 13 T maximum peak magnetic field of the ITER Central Solenoid (CS) coils and they must survive up to 60,000 electromagnetic cycles. Accordingly, prototype designs of CS cable-in-conduit-conductors (CICC) were electromagnetically tested over multiple magnetic field cycles and warm-up-cool-down scenarios in the SULTAN facility at CRPP. We report here a post mortem metallographic analysis of two CS CICC prototypes which exhibited some rate of irreversible performance degradation during cycling. The standard ITER CS CICC cable design uses a combination of superconducting and Cu strands, and because the Lorentz force on the strand is proportional to the transport current in the strand, removing the copper strands (while increasing the Cu:SC ratio of the superconducting strands) was proposed as one way of reducing the strand load. In this study we compare the two alternative CICCs, with and without Cu strands, keeping in mind that the degradation after SULTAN test was lower for the CICC without Cu strands. The post mortem metallographic evaluation revealed that the overall strand transverse movement was 20% lower in the CICC without Cu strands and that the tensile filament fractures found were less, both indications of an overall reduction in high tensile strain regions. Furthermore, it was interesting to see that the Cu strands in the mixed cable design (with higher degradation) helped reduce the contact stresses on the high pressure side of the CICC, but in either case, the strain reduction mechanisms were not enough to suppress cyclic degradation. Advantages and disadvantages of each conductor design are discussed here aimed to understand the sources of the degradation.

  1. Cryofixation of tissue specimens studied by cooling rate measurements and scanning electron microscopy.

    PubMed

    Zierold, K

    1980-03-01

    The freezing velocity, the most important parameter for the quality of cryofixation of biological objects, was measured in frog liver specimens. The cooling course was found to depend on the size of the specimen, the specimen support and the cooling medium used (liquid nitrogen, supercooled nitrogen, Freon 12 and propane). The results were compared with scanning electron micrographs of freeze fractures cryofixed in the same manner: Propane yielded the highest cooling rates and, consequently, the best structural preservation. Morphologically similar results were obtained by combining Freon 12 and very small specimen supports. Generally, it can be said that the smaller both specimen and specimen support are, the higher is the freezing rate and the better the structural preservation. The findings are discussed with regard to further possibilities of improving the cryofixation of biological tissue. PMID:7392964

  2. Rapid cooling rates at an active mid-ocean ridge from zircon thermochronology

    USGS Publications Warehouse

    Schmitt, Axel K.; Perfit, Michael R.; Rubin, Kenneth H.; Stockli, Daniel F.; Smith, Matthew C.; Cotsonika, Laurie A.; Zellmer, Georg F.; Ridley, W. Ian

    2011-01-01

    Oceanic spreading ridges are Earth's most productive crust generating environment, but mechanisms and rates of crustal accretion and heat loss are debated. Existing observations on cooling rates are ambiguous regarding the prevalence of conductive vs. convective cooling of lower oceanic crust. Here, we report the discovery and dating of zircon in mid-ocean ridge dacite lavas that constrain magmatic differentiation and cooling rates at an active spreading center. Dacitic lavas erupted on the southern Cleft segment of the Juan de Fuca ridge, an intermediate-rate spreading center, near the intersection with the Blanco transform fault. Their U–Th zircon crystallization ages (29.3-4.6+4.8 ka; 1δ standard error s.e.) overlap with the (U–Th)/He zircon eruption age (32.7 ± 1.6 ka) within uncertainty. Based on similar 238U-230Th disequilibria between southern Cleft dacite glass separates and young mid-ocean ridge basalt (MORB) erupted nearby, differentiation must have occurred rapidly, within ~ 10–20 ka at most. Ti-in-zircon thermometry indicates crystallization at 850–900 °C and pressures > 70–150 MPa are calculated from H2O solubility models. These time-temperature constraints translate into a magma cooling rate of ~ 2 × 10-2 °C/a. This rate is at least one order-of-magnitude faster than those calculated for zircon-bearing plutonic rocks from slow spreading ridges. Such short intervals for differentiation and cooling can only be resolved through uranium-series (238U–230Th) decay in young lavas, and are best explained by dissipating heat convectively at high crustal permeability.

  3. Rapid cooling rates at an active mid-ocean ridge from zircon thermochronology

    NASA Astrophysics Data System (ADS)

    Schmitt, Axel K.; Perfit, Michael R.; Rubin, Kenneth H.; Stockli, Daniel F.; Smith, Matthew C.; Cotsonika, Laurie A.; Zellmer, Georg F.; Ridley, W. Ian; Lovera, Oscar M.

    2011-02-01

    Oceanic spreading ridges are Earth's most productive crust generating environment, but mechanisms and rates of crustal accretion and heat loss are debated. Existing observations on cooling rates are ambiguous regarding the prevalence of conductive vs. convective cooling of lower oceanic crust. Here, we report the discovery and dating of zircon in mid-ocean ridge dacite lavas that constrain magmatic differentiation and cooling rates at an active spreading center. Dacitic lavas erupted on the southern Cleft segment of the Juan de Fuca ridge, an intermediate-rate spreading center, near the intersection with the Blanco transform fault. Their U-Th zircon crystallization ages (29.3 - 4.6 + 4.8 ka; 1σ standard error s.e.) overlap with the (U-Th)/He zircon eruption age (32.7 ± 1.6 ka) within uncertainty. Based on similar 238U- 230Th disequilibria between southern Cleft dacite glass separates and young mid-ocean ridge basalt (MORB) erupted nearby, differentiation must have occurred rapidly, within ~ 10-20 ka at most. Ti-in-zircon thermometry indicates crystallization at 850-900 °C and pressures > 70-150 MPa are calculated from H 2O solubility models. These time-temperature constraints translate into a magma cooling rate of ~ 2 × 10 - 2 °C/a. This rate is at least one order-of-magnitude faster than those calculated for zircon-bearing plutonic rocks from slow spreading ridges. Such short intervals for differentiation and cooling can only be resolved through uranium-series ( 238U- 230Th) decay in young lavas, and are best explained by dissipating heat convectively at high crustal permeability.

  4. Effects of Cooling Rate on Blocking Temperature and Paleointensity, Revisited: Old and New Results

    NASA Astrophysics Data System (ADS)

    Halgedahl, S. L.

    2002-12-01

    Recent years have witnessed a renaissance in experiments to determine paleointensities. Some of the most notable studies have focused on the rapidly chilled margins of oceanic pillow basalts; other studies have yielded paleointensities from single domain magnetite within parent crystals which cooled slowly within an igneous body. Yet, work by several authors has shown theoretically that cooling rate can affect the blocking temperature and the intensity of weak-field thermoremanent magnetization (TRM) acquired by single domain (SD) grains. If the natural cooling rate was sufficiently slow, a Thellier-Thellier paleointensity experiment can yield an ancient field value that is several tens of percent higher than the true field in which the particles originally cooled. In this talk, the theory of this effect is reviewed for SD magnetite. New calculations are presented, which account for a range of grain volumes and aspect ratios in SD magnetite particles, as well as for different sizes and shapes of the cooling body. These results are discussed in light of time variations in the virtual dipole moment and secular variation in direction of the earth's field.

  5. Effect of cooling rate on structural and electromagnetic properties of high-carbon ferrochrome powders

    NASA Astrophysics Data System (ADS)

    Yang, Jian-ping; Chen, Jin; Hao, Jiu-jiu; Guo, Li-na; Liu, Jin-ying

    2016-03-01

    The structural and electromagnetic properties of high-carbon ferrochrome powders (HCFCP) obtained at different cooling rates were respectively investigated by means of optical microscope, X-ray diffractometer, electron probe as well as the vector network analyzer in the frequency range of 1-18 GHz. The results show that the cell structure of main phase, (Cr,Fe)7C3, transforms from hexagonal to orthogonal with the improvement of cooling rate. Meanwhile the mass ratio of Cr to Fe in (Cr,Fe)7C3 gradually declines, while that for CrFe goes up. Both the real part and the imaginary part of relative complex permittivity of HCFCP are in an increasing order with cooling rate rising in most frequencies. For comparison, the relative complex permeability presents an opposite changing tendency. The peaks of the imaginary part of relative complex permeability appearing in low and high frequencies are attributed to nature resonance. The reflection loss of HCFCP gradually decreases as cooling rate reduces and frequency enhances. At 2.45 GHz, the algebraic sum of dielectric loss factor and magnetic loss factor increases first and then decreases in the temperature extent from 298 K to 1273 K.

  6. AN EMPIRICAL MEASURE OF THE RATE OF WHITE DWARF COOLING IN 47 TUCANAE

    SciTech Connect

    Goldsbury, R.; Heyl, J.; Richer, H. B.; Woodley, K. A. E-mail: heyl@phas.ubc.ca E-mail: kwoodley@phas.ubc.ca; and others

    2012-11-20

    We present an empirical determination of the white dwarf cooling sequence in the globular cluster 47 Tucanae. Using spectral models, we determine temperatures for 887 objects from Wide Field Camera 3 data, as well as 292 objects from data taken with the Advanced Camera for Surveys. We make the assumption that the rate of white dwarf formation in the cluster is constant. Stellar evolution models are then used to determine the rate at which objects are leaving the main sequence, which must be the same as the rate at which objects are arriving on the white dwarf sequence in our field. The result is an empirically derived relation between temperature (T {sub eff}) and time (t) on the white dwarf cooling sequence. Comparing this result to theoretical cooling models, we find general agreement with the expected slopes between 20,000 K and 30,000 K and between 6000 K and 20,000 K, but the transition to the Mestel cooling rate of T {sub eff}{proportional_to}t {sup -0.4} is found to occur at hotter temperatures, and more abruptly than is predicted by any of these models.

  7. The effect of cooling rates on the apparent fragility of Zr-based bulk metallic glasses

    SciTech Connect

    Evenson, Zach; Gallino, Isabella; Busch, Ralf

    2010-06-15

    We investigate the behavior of the kinetic fragility parameter D* as different cooling rates are applied to samples of the Zr{sub 57}Cu{sub 15.4}Ni{sub 12.6}Al{sub 10}Nb{sub 5} and Zr{sub 58.5}Cu{sub 15.6}Ni{sub 12.8}Al{sub 10.3}Nb{sub 2.8} bulk metallic glass formers. The glassy samples are heated into the supercooled liquid region using differential scanning calorimetry (DSC) and cooled back into the glassy state with sets of different cooling rates, q{sub C}. The shifts in the glass transition are measured by determining the onset glass transition temperature, T{sub g}{sup onset}, as well as the limiting fictive temperature, T{sub f}{sup '}, upon reheating with a set of heating rates, q{sub H}. We then model the data by assuming a Vogel-Fulcher-Tammann-type behavior in the structural relaxation time, {tau}, and observe an apparent increase in the kinetic fragility parameter for slower cooling rates. These results show that fragilities calculated from DSC scans, where q{sub H}=q{sub C} are in good agreement with those from equilibrium viscosity data recently obtained by three-point beam-bending.

  8. The relationship between sperm quality in cool-shipped semen and embryo recovery rate in horses.

    PubMed

    Love, C C; Noble, J K; Standridge, S A; Bearden, C T; Blanchard, T L; Varner, D D; Cavinder, C A

    2015-12-01

    The relationship between the quality of cool-shipped stallion semen and fertility has not been adequately described. This study evaluated sperm quality of cool-shipped semen from 459 ejaculates (N = 130 stallions) that were used for insemination of 196 embryo donor mares (n = 496 estrous cycles). Embryo recovery rate (ERR; %) increased, as all sperm measures (e.g., motility, viability, DNA quality, morphology, concentration, and total number) increased. Threshold values are reported for each sperm quality measure (e.g., total sperm motility ≥ 65%) that separate two ERR groups (e.g., average: ∼50% ERR; high: ∼65% ERR). PMID:26363735

  9. Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure

    NASA Astrophysics Data System (ADS)

    Ryltsev, R. E.; Klumov, B. A.; Chtchelkatchev, N. M.; Shunyaev, K. Yu.

    2016-07-01

    Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ṡ 109, 1013) K/s. Investigating short- and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 ṡ 109 K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at γmin.

  10. Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure.

    PubMed

    Ryltsev, R E; Klumov, B A; Chtchelkatchev, N M; Shunyaev, K Yu

    2016-07-21

    Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ⋅ 10(9), 10(13)) K/s. Investigating short- and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 ⋅ 10(9) K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at γmin. PMID:27448895

  11. [Surface analysis and metallographic studies of Judet's prosthesis].

    PubMed

    Häussler, G; Polster, J

    1985-01-01

    Surveying a quantity of 25 prostheses type Judet by stereoscopy and scanning electron microscopy in all specimen contaminations of the surface were found. By X-ray microanalysis these contaminations were ascertained to be mainly residues of the casting mould. Furthermore, tooling residues from the sandblast (e.g. grains of corundum or glass) were found. A metallographic investigation, which was performed thereupon on two randomly selected specimen, shows clusters of microporosities in the cross sections and carbides in the grain boundaries. PMID:4050038

  12. Metallographic techniques for evaluation of thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Brindley, William J.; Leonhardt, Todd A.

    1990-01-01

    The performance of ceramic thermal barrier coatings is strongly dependent on the amount and shape of the porosity in the coating. Current metallographic techniques do not provide polished surfaces that are adequate for a repeatable interpretation of the coating structures. A technique recently developed at NASA-Lewis for preparation of thermal barrier coating sections combines epoxy impregnation, careful sectioning and polishing, and interference layering to provide previously unobtainable information on processing-induced porosity. In fact, increased contrast and less ambiguous structure developed by the method make automatic quantitative metallography a viable option for characterizing thermal barrier coating structures.

  13. New metallographic preparation techniques for tantalum and tantalum alloys

    SciTech Connect

    Kelly, A.M.; Bingert, S.R.; Reiswig, R.D.

    1995-09-01

    Two new metallographic techniques have been developed for tantalum and its alloys. The first is a chemical polishing method that can even be used on specimens immediately after grinding on silicon carbide papers. The second is an etching technique that even delineates low-angle grain boundaries, making it particularly suitable for quantitative grain size measurements. It has also been determined that these are suitable for the preparation of a surprisingly large variety of other metals and alloys, including, titanium, tungsten, Ti-6Al-4V, molybdenum, a Zr-Ti-Cu-Ni alloy, a Ti-Ta-Sc alloy, Fansteel 85, and a Hf-Zr alloy to name a few.

  14. COOLING RATES FOR RELATIVISTIC ELECTRONS UNDERGOING COMPTON SCATTERING IN STRONG MAGNETIC FIELDS

    SciTech Connect

    Baring, Matthew G.; Wadiasingh, Zorawar; Gonthier, Peter L. E-mail: zw1@rice.edu

    2011-05-20

    For inner magnetospheric models of hard X-ray and gamma-ray emission in high-field pulsars and magnetars, resonant Compton upscattering is anticipated to be the most efficient process for generating continuum radiation. This is in part due to the proximity of a hot soft photon bath from the stellar surface to putative radiation dissipation regions in the inner magnetosphere. Moreover, because the scattering process becomes resonant at the cyclotron frequency, the effective cross section exceeds the classical Thomson value by over two orders of magnitude, thereby enhancing the efficiency of continuum production and the cooling of relativistic electrons. This paper presents computations of the electron cooling rates for this process, which are needed for resonant Compton models of non-thermal radiation from such highly magnetized pulsars. The computed rates extend previous calculations of magnetic Thomson cooling to the domain of relativistic quantum effects, sampled near and above the quantum critical magnetic field of 44.13 TG. This is the first exposition of fully relativistic, quantum magnetic Compton cooling rates for electrons, and it employs both the traditional Johnson and Lippmann cross section and a newer Sokolov and Ternov (ST) formulation of Compton scattering in strong magnetic fields. Such ST formalism is formally correct for treating spin-dependent effects that are important in the cyclotron resonance and has not been addressed before in the context of cooling by Compton scattering. The QED effects are observed to profoundly lower the rates below extrapolations of the familiar magnetic Thomson results, as expected, when recoil and Klein-Nishina reductions become important.

  15. Cooling rates and crystallization dynamics of shallow level pegmatite-aplite dikes, San Diego County, California

    USGS Publications Warehouse

    Webber, Karen L.; Simmons, William B.; Falster, Alexander U.; Foord, Eugene E.

    1999-01-01

    Pegmatites of the Pala and Mesa Grande Pegmatite Districts, San Diego County, California are typically thin, sheet-like composite pegmatite-aplite dikes. Aplitic portions of many dikes display pronounced mineralogical layering referred to as "line rock," characterized by fine-grained, garnet-rich bands alternating with albite- and quartz-rich bands. Thermal modeling was performed for four dikes in San Diego County including the 1 m thick Himalaya dike, the 2 m thick Mission dike, the 8 m thick George Ashley dike, and the 25 m thick Stewart dike. Calculations were based on conductive cooling equations accounting for latent heat of crystallization, a melt emplacement temperature of 650 °C into 150 °C fractured, gabbroic country rock at a depth of 5 km, and an estimated 3 wt% initial H2O content in the melt. Cooling to -5 cm/s. Crystal size distribution (CSD) studies of garnet from layered aplites suggest growth rates of about 10-6 cm/s. These results indicate that the dikes cooled and crystallized rapidly, with variable nucleation rates but high overall crystal-growth rates. Initial high nucleation rates coincident with emplacement and strong undercooling can account for the millimeter-size aplite grains. Lower nucleation rates coupled with high growth rates can explain the decimeter-size minerals in the hanging walls, cores, and miarolitic cavities of the pegmatites. The presence of tourmaline and/or lepidolite throughout these dikes suggests that although the melts were initially H2O-undersaturated, high melt concentrations of incompatible (or fluxing) components such as B, F, and Li (±H2O), aided in the development of large pegmatitic crystals that grew rapidly in the short times suggested by the conductive cooling models.

  16. Cooling rate of an active Hawaiian lava flow from nighttime spectroradiometer measurements

    NASA Astrophysics Data System (ADS)

    Flynn, Luke P.; Mouginis-Mark, Peter J.

    1992-09-01

    A narrow-band spectroradiometer has been used to make nighttime measurements of the Phase 50 eruption of Pu'u O'o, on the East Rift Zone of Kilauea Volcano, Hawaii. On February 19, 1992, a GER spectroradiometer was used to determine the cooling rate of an active lava flow. This instrument collects 12-bit data between 0.35 to 3.0 microns at a spectral resolution of 1-5 nm. Thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period (21:27-22:26 HST) from which the cooling of the lava surface has been investigated. A two-component thermal mixing model (Flynn, 1992) applied to data for the flow immediately on emplacement gave a best-fit crustal temperature of 768 C, a hot component at 1150 C, and a hot radiating area of 3.6 percent of the total area. Over a 52-minute period (within the time interval between flow resurfacings) the lava flow crust cooled by 358 to 410 C at a rate that was as high as 15 C/min. The observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement.

  17. Evaluation of Cooling Rate Effects on the Mechanical Properties of Die Cast Magnesium Alloy AM60

    NASA Astrophysics Data System (ADS)

    Sharifi, P.; Fan, Y.; Anaraki, H. B.; Banerjee, A.; Sadayappan, K.; Wood, J. T.

    2016-10-01

    With the increased application of magnesium high-pressure die castings (HPDC), it is necessary to better understand process-structure-mechanical properties. In the case of HPDC, ductility and yield strength strongly depend on porosity, grain size, and the skin thickness. In this contribution, a new method is developed which employs knowledge of local cooling rates to predict the grain size and the skin thickness of HPDC magnesium components. The centreline cooling curve, together with the die temperature, and the thermodynamic properties of the alloy are then used as inputs to compute the solution to the Stefan problem of a moving phase boundary, thereby providing the through-thickness cooling curves at each chosen location of the casting. The local cooling rate is used to calculate the resulting grain size and skin thickness via established relationships. The prediction of skin thickness and average grain size of skin region determined from this method compares quite well with the experimental results. Due to the presence of externally solidified grains, this method underestimates the grain size value in the core region, as compared to the experiment. Finally, we predict the locally varying yield strength using a modified Hall-Petch equation.

  18. Cooling rate of an active Hawaiian lava flow from nighttime spectroradiometer measurements

    NASA Technical Reports Server (NTRS)

    Flynn, Luke P.; Mouginis-Mark, Peter J.

    1992-01-01

    A narrow-band spectroradiometer has been used to make nighttime measurements of the Phase 50 eruption of Pu'u O'o, on the East Rift Zone of Kilauea Volcano, Hawaii. On February 19, 1992, a GER spectroradiometer was used to determine the cooling rate of an active lava flow. This instrument collects 12-bit data between 0.35 to 3.0 microns at a spectral resolution of 1-5 nm. Thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period (21:27-22:26 HST) from which the cooling of the lava surface has been investigated. A two-component thermal mixing model (Flynn, 1992) applied to data for the flow immediately on emplacement gave a best-fit crustal temperature of 768 C, a hot component at 1150 C, and a hot radiating area of 3.6 percent of the total area. Over a 52-minute period (within the time interval between flow resurfacings) the lava flow crust cooled by 358 to 410 C at a rate that was as high as 15 C/min. The observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement.

  19. Effect of Cooling Rate on the Microstructure of Laser-Remelted INCONEL 718 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Yaocheng; Li, Zhuguo; Nie, Pulin; Wu, Yixiong

    2013-12-01

    The rapid cooling rate was achieved during laser remelting with high scanning speed. The microstructure and precipitations in the INCONEL 718 remelted layer were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and solid phase microextraction (SPME). The phase transition temperatures were carried out by differential thermal analysis (DTA). The results showed that columnar-dendritic and equiaxial structures appeared in different regions of the remelted layer. The dendritic spacing of the columnar dendrite and equiaxed grain size decreased with increasing scanning speed. The precipitations in the remelted layer consisted of Laves, granular phase, and a small quantity of quadrangular nitride (Ti, Nb)N. The granular phase Nb(Al, Ti) was precipitated at about 1272 K (999 °C) with the spontaneous decomposition of the supersaturation Laves during the cooling stage, and the small-size granule became coarsened to 0.2 to 0.9 μm during the cooling stage. The noncoherent relationship existed between the granular phase and austenite, and the coarsening of granule was related to the cube root of the diffusion coefficient, interfacial energy, and diffusion time. The microhardness of the remelted layer was increased by increasing the cooling rate due to the Nb atomic solid solution strengthening caused by the distorted elastic stress field and the short-range internal stress.

  20. Geomagnetic superchrons and time variations in the cooling rate of the core

    NASA Astrophysics Data System (ADS)

    Olson, P.

    2015-12-01

    Polarity reversal systematics from numerical dynamos are used to explore the relationship between geomagnetic reversal frequency, including geomagnetic superchrons, and time variations in the rate of the cooling of the core. We develop a parameterization of the average reversal frequency from numerical dynamos in terms of the core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit of this parameterization to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS) reveals that a decrease in core heat flux relative to present-day of approximately 30% can account for the Cretaceous Normal Polarity and Kiaman Reversed Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic GPTS imply a core heat flux approximately 20% higher than at present-day. Low heat flux and slow cooling of the core inferred during the Kiaman Reversed Polarity Superchron is qualitatively consistent with predictions from mantle global circulation models (mantle GCMs) that show a reduction in mantle convective activity during the time of Pangea, whereas these same mantle GCMs and most plate motion reconstructions predict fast core cooling during the Cretaceous Normal Polarity Superchron, suggesting that the cooling rate of the core is not generally in phase with variations in plate motions.

  1. Long-term stability of global erosion rates and weathering during late-Cenozoic cooling.

    PubMed

    Willenbring, Jane K; von Blanckenburg, Friedhelm

    2010-05-13

    Over geologic timescales, CO(2) is emitted from the Earth's interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions. Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion are superimposed on fluctuations in organic carbon burial. Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation. Widespread observations of a recent (0-5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them. Accelerated uplift and global cooling have been given as possible causes, but because of the links between rates of erosion and the correlated rate of weathering, an increase in the drawdown of CO(2) that is predicted to follow may be the cause of global climate change instead. However, globally, rates of uplift cannot increase everywhere in the way that apparent sedimentation rates do. Moreover, proxy records of past atmospheric CO(2) provide no evidence for this large reduction in recent CO(2) concentrations. Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record. As evidence, we recast the ocean dissolved (10)Be/(9)Be isotope system as a weathering proxy spanning the past approximately 12 Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and

  2. Diffusion kinetics of samarium and neodymium in garnet, and a method for determining cooling rates of rocks

    PubMed

    Ganguly; Tirone; Hervig

    1998-08-01

    Experimental determinations of the diffusion coefficients of samarium and neodymium in almandine garnet and theoretical considerations show that one cannot assign a sufficiently restricted range of closure temperature, TC, to the samarium-neodymium decay system in garnet for the purpose of constraining the cooling rate. However, it is shown that the samarium-neodymium cooling age of garnet can be used to calculate both cooling rate and TC if the temperature and age at the peak metamorphic conditions are known.

  3. Reassessing the cooling rate and geologic setting of Martian meteorites MIL 03346 and NWA 817

    NASA Astrophysics Data System (ADS)

    Richter, Frank; Chaussidon, Marc; Mendybaev, Ruslan; Kite, Edwin

    2016-06-01

    Lithium concentration and isotopic fractionation profiles across augite grains from two Martian meteorites - MIL 03346 and NWA 817 - were used to determine their thermal history and implications for their geologic setting. The iron-magnesium zoning and associated magnesium isotopic fractionation of olivine grains from NWA 817 were also measured and provide a separate estimate of the cooling rate. The observed correlation of concentration with isotopic fractionation provides the essential evidence that the zoning of these grains was in fact due to diffusion and thus can be used as a measure of their cooling rate. The diffusion rate of lithium in augite depends on the oxygen fugacity, which has to be taken into account when determining a cooling rate based on the lithium zoning. The Fe-Mg exchange in olivine is much less sensitive to oxygen fugacity, but it is significantly anisotropic and for this reason we determined the direction relative to crystallographic axes of the line along which the Fe-Mg zoning was measured. We found that the cooling rate of NWA 817 determined from the lithium zoning in augite grains and that based on the Fe-Mg zoning of olivines are in good agreement at an oxygen fugacity close to that of quartz-fayalite-magnetite oxygen buffer. The cooling rate of MIL 03346 was found to be resolvably faster than that of NWA 817 - of the order of 1 °C/h for the former and of the order of 0.2 °C/h for the latter. An important observation regarding the history of MIL 03346 and NWA 817 is that the lithium and Fe-Mg zoning are only observed where the augite or olivine is in contact with the mesostasis, which implies that they were already about 80% crystallized at the time diffusion began. The augite and olivine core compositions while very homogeneous are not in equilibrium with each other, which we interpret to imply that prior to the rapid cooling there must have been a protracted period of the order of years above the solidus, during which the much

  4. A New DTA Method for Measuring Critical Cooling Rate for Glass Formation

    NASA Technical Reports Server (NTRS)

    Ray, Chandra S.; Reis, Signo T.; Brow, Richard K.; Holand, Wolfram; Rheinberger, Volker

    2004-01-01

    A new differential thermal analysis (DTA) experimental method has been developed to determine the critical cooling rate for glass formation, R(sub c). The method, which is found especially suitable for melts that, upon cooling, have a small heat of crystallization or a very slow crystallization rate, has been verified using a 38Na2O-62SiO2 (mol%) melt with a known R(sub c) (-approx. 19 C/min), then used to determine R(sub c) for two complex lithium silicate glass forming melts. The new method is rapid, easy to conduct and yields values for R(sub c) that are in excellent agreement with the R(sub c)-values measured by standard DTA techniques.

  5. Constraining star formation rates in cool-core brightest cluster galaxies

    NASA Astrophysics Data System (ADS)

    Mittal, Rupal; Whelan, John T.; Combes, Françoise

    2015-07-01

    We used broad-band imaging data for 10 cool-core brightest cluster galaxies (BCGs) and conducted a Bayesian analysis using stellar population synthesis to determine the likely properties of the constituent stellar populations. Determination of ongoing star formation rates (SFRs), in particular, has a direct impact on our understanding of the cooling of the intracluster medium (ICM), star formation and AGN-regulated feedback. Our model consists of an old stellar population and a series of young stellar components. We calculated marginalized posterior probability distributions for various model parameters and obtained 68 per cent plausible intervals from them. The 68 per cent plausible interval on the SFRs is broad, owing to a wide range of models that are capable of fitting the data, which also explains the wide dispersion in the SFRs available in the literature. The ranges of possible SFRs are robust and highlight the strength in such a Bayesian analysis. The SFRs are correlated with the X-ray mass deposition rates (the former are factors of 4-50 lower than the latter), implying a picture where the cooling of the ICM is a contributing factor to star formation in cool-core BCGs. We find that 9 out of 10 BCGs have been experiencing starbursts since 6 Gyr ago. While four out of nine BCGs seem to require continuous SFRs, five out of nine seem to require periodic star formation on intervals ranging from 20 to 200 Myr. This time-scale is similar to the cooling time of the ICM in the central (<5 kpc) regions.

  6. Simple strategies for inclusion of Voigt effects in infrared cooling rate calculations.

    PubMed

    Fels, S B

    1979-08-01

    A line shape with rectangular core and nu(-2) wings is shown to be an excellent alias for the Voigt profile when calculating equivalent widths. It leads to closed analytic forms in the commonly employed random models and gives highly accurate ozone cooling rates. An even simpler device for applications where less accurate results are required involves use of the Lorentz profile with a width which does not vanish at zero pressure. PMID:20212722

  7. Therml & Gravitational Stress in Si Wafers; Lim. on Process Htg & Cool. Rates

    1997-01-14

    The MacWafer code determines maximum allowable processing temperatures and maximum heating and cooling rates for thermal processing of silicon semiconductor wafers in single and multiple wafer furnaces. The program runs interactively on Macintosh, PC, and workstation computers. Execution time is typically 20 seconds on a Macintosh 68040 processor operating at 33 MHz. Gravitational stresses and displacements are first calculated based on the user''s input of a support system consisting of a ring beneath the wafermore » and/or arbitrarily placed point supports. The maximum operating temperature is then deduced by comparing the calculated gravitational stresses with the temperature-dependent wafer strength. At lower temperatures, the difference between wafer strength and gravitational stress is used to determine the allowable thermal stress, and hence the allowable radial temperature difference across the wafer. Finally, an analytical model of radial heat transfer in a batch furnace yields the maximum heating or cooling rate as a function of the allowable temperature difference based on the user''s inputs of wafer spacing and furnace power. Outputs to the screen include plots of stress components and vertical displacement, as well as tables of maximum stresses and maximum heating and cooling rates as a function of temperature. All inputs and outputs may be directed to user-named files for further processing or graphical display.« less

  8. Survival and fertility rate of cooled dromedary camel spermatozoa supplemented with catalase enzyme.

    PubMed

    Medan, Mohamed Sabry; Absy, Gamal; Zeidan, Alaa Elsayed; Khalil, Medhat Hussein; Khalifa, Hesham Hussein; Abdel-Salaam, Atef Mahrous; Abdel-Khalek, Tarek Mohammad

    2008-02-01

    The present study was planned to study the effects of addition of different concentrations of catalase enzyme (0, 250, 500 and 1,000 IU/ml) to cooled dromedary camel semen extended with tris-yolk-fructose extender on semen quality during storage at 5 C for up to 5 days. Conception rates of she-camels artificially inseminated with whole fresh or extended cooled dromedary camel semen with or without 500 IU/ml catalase enzyme were also estimated. The results showed that addition of catalase enzyme at concentrations of 250 or 500 IU/ml to extended cooled dromedary camel semen significantly increased (P<0.01) the percentage of sperm motility and significantly decreased (P<0.01) the percentages of dead spermatozoa, sperm abnormalities and acrosomal damage. The highest (P<0.01) percentage of sperm motility was recorded with extended cooled dromedary camel semen supplemented with catalase enzyme at a concentration of 500 IU/ml, and the lowest (P<0.01) value was recorded with catalase enzyme at a concentration of 1000 IU/ml. On the other hand, the lowest (P<0.01) percentages of dead spermatozoa, sperm abnormalities and acrosomal damage of spermatozoa were recorded with extended cooled dromedary camel semen supplemented with 500 IU/ml, and the highest (P<0.01) values were recorded with catalase enzyme at a concentration of 1,000 IU/ml. Advancement of the storage time at 5 C significantly decreased (P<0.01) the percentage of sperm motility and significantly increased (P<0.01) the percentages of dead spermatozoa, sperm abnormalities and acrosomal damage of spermatozoa. Moreover, the conception rates of she-camels artificially inseminated with whole fresh, extended cooled dromedary camel semen free-catalase enzyme and extended cooled dromedary camel semen supplemented with catalase enzyme at a concentration of 500 IU/ml were 46.15, 22.22 and 37.50%, respectively. In conclusion, the results show that addition of catalase enzyme at a concentration of 500 IU/ml to semen extender

  9. Development of an intelligent system for cooling rate and fill control in GMAW

    SciTech Connect

    Einerson, C.J.; Smartt, H.B.; Johnson, J.A.; Taylor, P.L.; Moore, K.L.

    1992-09-01

    A control strategy for gas metal arc welding (GMAW) is developed in which the welding system detects certain existing conditions and adjusts the process in accordance to pre-specified rules. This strategy is used to control the reinforcement and weld bead centerline cooling rate during welding. Relationships between heat and mass transfer rates to the base metal and the required electrode speed and welding speed for specific open circuit voltages are taught to a artificial neural network. Control rules are programmed into a fuzzy logic system. TRADITOINAL CONTROL OF THE GMAW PROCESS is based on the use of explicit welding procedures detailing allowable parameter ranges on a pass by pass basis for a given weld. The present work is an exploration of a completely different approach to welding control. In this work the objectives are to produce welds having desired weld bead reinforcements while maintaining the weld bead centerline cooling rate at preselected values. The need for this specific control is related to fabrication requirements for specific types of pressure vessels. The control strategy involves measuring weld joint transverse cross-sectional area ahead of the welding torch and the weld bead centerline cooling rate behind the weld pool, both by means of video (2), calculating the required process parameters necessary to obtain the needed heat and mass transfer rates (in appropriate dimensions) by means of an artificial neural network, and controlling the heat transfer rate by means of a fuzzy logic controller (3). The result is a welding machine that senses the welding conditions and responds to those conditions on the basis of logical rules, as opposed to producing a weld based on a specific procedure.

  10. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    NASA Astrophysics Data System (ADS)

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  11. Effect of cooling-heating rate on sol-gel transformation of fish gelatin-gum arabic complex coacervate phase.

    PubMed

    Anvari, Mohammad; Chung, Donghwa

    2016-10-01

    The objective of this study was to characterize influence of different cooling and heating rates on gelation of fish gelatin (FG)-gum arabic (GA) complex coacervate phase using rheological measurements. For the coacervate phase prepared at 10°C, the gelling temperature, melting temperature, gel strength, and stress relaxation decreased with increasing cooling or heating rate, however, no gelation was observed at the highest cooling rate of 0.05°C/min. Similar trends were obtained for the coacervates phase prepared at 30°C, but the gelation did not occur at a cooling rate of 0.033 or 0.05°C/min. The results indicated that rheological properties of FG-GA coacervate gels were highly dependent to the cooling process, where more thermos-stable and stronger gels formed at slower cooling. This was probably because of higher degree of molecular rearrangements, more hydrogen bindings, and formation of greater junction zones into the gel network at slower cooling rates. However, all of the FG-GA coacervate gels obtained at different cooling rates were classified as a weak physical gel.

  12. A potential metallographic technique for the investigation of pipe bombings.

    PubMed

    Walsh, Graham A; Inal, Osman T; Romero, Van D

    2003-09-01

    This study was conducted in an attempt to develop a metallographic method for the investigation of pipe bombings. Three common pipe materials, ASTM A53 steel, AISI 304L stainless steel, and 6061-T6 aluminum, were shock-loaded using five high explosives and three propellants. The explosives used were ANFO, Composition C4, C6 detasheet, nitroglycerine-based dynamite, and flake TNT. The propellants used were FFFFg black powder. Red Dot smokeless powder, and Turbo Fuel A. The post-blast microstructure, hardness, and, in the case of 304L, transformed martensite content were examined for each test. The damage done to the microstructure was found to increase with increasing detonation velocity of the explosives and increase in pressure generated by the shock-metal interaction. Material hardness and, in the case of 304L, martensite content showed a sharp increase followed by a plateau as the shock pressure and detonation velocity increased.

  13. Cooling rate effects on thermal, structural, and microstructural properties of bio-hydroxyapatite obtained from bovine bone.

    PubMed

    Ramirez-Gutierrez, Cristian F; Palechor-Ocampo, Anderzon F; Londoño-Restrepo, Sandra M; Millán-Malo, Beatriz M; Rodriguez-García, Mario E

    2016-02-01

    This article is focused on the study of cooling rate effects on the thermal, structural, and microstructural properties of hydroxyapatite (HAp) obtained from bovine bone. A three-step process was used to obtain BIO-HAp: hydrothermal, calcinations, and cooling. Calcined samples in a furnace and cooling in air (HAp-CAir), water (HAp-CW), and liquid nitrogen (HAp-CN2), as well as an air cooled sample inside the furnace (HAp-CFAir), were studied. According to this study, the low cooling rate that was achieved for air cooled samples inside the furnace produce single crystal BIO-HAp with better crystalline quality; other samples exhibited polycrystalline structures forming micron and submicron grains. PMID:25952013

  14. Cooling rate effects on thermal, structural, and microstructural properties of bio-hydroxyapatite obtained from bovine bone.

    PubMed

    Ramirez-Gutierrez, Cristian F; Palechor-Ocampo, Anderzon F; Londoño-Restrepo, Sandra M; Millán-Malo, Beatriz M; Rodriguez-García, Mario E

    2016-02-01

    This article is focused on the study of cooling rate effects on the thermal, structural, and microstructural properties of hydroxyapatite (HAp) obtained from bovine bone. A three-step process was used to obtain BIO-HAp: hydrothermal, calcinations, and cooling. Calcined samples in a furnace and cooling in air (HAp-CAir), water (HAp-CW), and liquid nitrogen (HAp-CN2), as well as an air cooled sample inside the furnace (HAp-CFAir), were studied. According to this study, the low cooling rate that was achieved for air cooled samples inside the furnace produce single crystal BIO-HAp with better crystalline quality; other samples exhibited polycrystalline structures forming micron and submicron grains.

  15. Estimates of Collisional Cooling and Quenching Rates for Atomic and Molecular Ion Collisions with Ultracold Atoms.

    NASA Astrophysics Data System (ADS)

    Smith, Winthrop; Wells, James

    2009-05-01

    Translational cross sections and rate coefficients for cold ion-neutral elastic and charge-exchange collisions (either atomic or molecular) are >> larger (˜10^6 a.u.) than neutral-neutral collisions at the same CM energy. This is due to the long range polarization potential V(R) = -C4/R^4, where C4 is proportional to the polarizability of the neutral partner. Thus collisions between ultracold alkali atoms (trapped in a magneto-optic trap or MOT) and low-energy ions can be used for sympathetic cooling experiments. We are building a prototype hybrid-trap apparatus [1] that applies these principles to collisions of Ca^+ ions (which can be laser pre-cooled) with MOT-trapped ultracold Na atoms. Some calculations on this system and other related ion-neutral systems have been published [2] and some initial experiments on other ion-neutral species have begun [3]. Estimates of cooling and quenching rates in the low K-mK CM energy range for Ca+ on Na and other cases will be presented and possible experiments described. [1] Winthrop W. Smith, Oleg P. Makarov and Jian Lin, J. Modern Optics 52, 2253 (2005). [2] R. Côt'e and A. Dalgarno, Phys. Rev. A 62, 012709 (2000); R. Côt'e, Phys. Rev. Lett. 85, 5316 (2000). [3] A. Grier, M. Cetina, F.Orucevic, and V. Vuletic, ArXiv atom-ph/0808.3620.

  16. Helium release rates and ODH calculations from RHIC magnet cooling line failure

    SciTech Connect

    Liaw, C.J.; Than, Y.; Tuozzolo, J.

    2011-03-28

    A catastrophic failure of the magnet cooling lines, similar to the LHC superconducting bus failure incident, could discharge cold helium into the RHIC tunnel and cause an Oxygen Deficiency Hazard (ODH) problem. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the insulating vacuum volumes and discharging via the reliefs into the RHIC tunnel, had been developed. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces are included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Results, including helium discharge rates, helium inventory loss, and the resulting oxygen concentration in the RHIC tunnel area, are reported. Good agreement had been achieved when comparing the simulation results, a RHIC sector depressurization test measurement, and some simple analytical calculations.

  17. The effect of photochemical models on calculated equilibria and cooling rates in the stratosphere

    NASA Technical Reports Server (NTRS)

    Blake, D.; Lindzen, R. S.

    1973-01-01

    Simplified models were developed for radiative heating and cooling and for ozone photochemistry in the region 22-60 km. The latter permit the inclusion of nitrogen and hydrogen reactions in addition to simple oxygen reactions. The simplicity of the scheme facilitates the use of a wide variety of cooling and reaction rates. It is shown that joint radiative-photochemical equilibrium is appropriate to the mean state of the atmosphere between 35 and 60 km. The relaxation of perturbations from joint radiative-photochemical equilibrium was also investigated. In all cases the coupling between temperature dependent ozone photochemistry and radiation lead to a reduction of the thermal relaxation time from its purely radiative value. The latter, which amounts to about 10 days, is reduced to 2-4 days at heights of 31-35 km. This greatly enhances the dissipation of waves traveling through the stratosphere.

  18. Hardening by cooling rate control and post-firing heat treatment in Pd-Ag-Sn alloy for bonding porcelain.

    PubMed

    Yu, Young-Jun; Seol, Hyo-Joung; Cho, Mi-Hyang; Kim, Hyung-Il; Kwon, Yong Hoon

    2016-01-01

    The aim of this study was to determine the hardening effect by controlling the cooling rate during the porcelain firing process and performing an additional post-firing heat treatment in a Pd-Ag-Sn alloy. The most effective cooling rate for alloy hardening was determined by cooling the specimens at various cooling rates after oxidation treatment. A subsequent porcelain firing simulation followed by cooling at the selected cooling rate was performed. A post-firing heat treatment was then done at 600°C in a porcelain furnace. The hardening mechanism was characterized by a hardness test, X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Alloy softening occurred during the porcelain firing process followed by cooling at a controlled cooling rate. A post-firing heat treatment allowed apparent precipitation hardening. It is advisable to perform a postfiring heat treatment at 600°C in a porcelain furnace by annealing metal substructure after porcelain fusing.

  19. Hardening by cooling rate control and post-firing heat treatment in Pd-Ag-Sn alloy for bonding porcelain.

    PubMed

    Yu, Young-Jun; Seol, Hyo-Joung; Cho, Mi-Hyang; Kim, Hyung-Il; Kwon, Yong Hoon

    2016-01-01

    The aim of this study was to determine the hardening effect by controlling the cooling rate during the porcelain firing process and performing an additional post-firing heat treatment in a Pd-Ag-Sn alloy. The most effective cooling rate for alloy hardening was determined by cooling the specimens at various cooling rates after oxidation treatment. A subsequent porcelain firing simulation followed by cooling at the selected cooling rate was performed. A post-firing heat treatment was then done at 600°C in a porcelain furnace. The hardening mechanism was characterized by a hardness test, X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Alloy softening occurred during the porcelain firing process followed by cooling at a controlled cooling rate. A post-firing heat treatment allowed apparent precipitation hardening. It is advisable to perform a postfiring heat treatment at 600°C in a porcelain furnace by annealing metal substructure after porcelain fusing. PMID:27041022

  20. Parameterization of radiative heating and cooling rates in the stratosphere of Jupiter

    NASA Astrophysics Data System (ADS)

    Kuroda, Takeshi; Medvedev, Alexander S.; Hartogh, Paul

    2014-11-01

    We present a newly developed parameterization of radiative heating and cooling for Jupiter's upper troposphere and stratosphere (103 to 10-3hPa ) suitable for general circulation models. The scheme is based on the correlated k-distribution approach, and accounts for all the major radiative mechanisms in the jovian atmosphere: heating due to absorption of solar radiation by methane, cooling in the infrared by methane, acetylene, ethane, and collisionally-induced molecular hydrogen-hydrogen, and molecular hydrogen-helium transitions. The results with the scheme are compared with line-by-line calculations to demonstrate that the accuracy of the scheme is within 10%. The parameterization was applied to study the sensitivity of the heating/cooling rates due to variations of mixing ratios of hydrocarbon molecules. It was also used for calculating the radiative-convective equilibrium temperature, which is in agreement with observations in the equatorial region. In midlatitudes, the equilibrium temperature is approximately 10 K colder. Our results suggest that the radiative forcing in the upper stratosphere is much stronger than it was thought before. In particular, the characteristic radiative relaxation time decreases exponentially with height from 108s near the tropopause to 105s in the upper stratosphere.

  1. Curie temperatures of titanomagnetite in ignimbrites: Effects of emplacement temperatures, cooling rates, exsolution, and cation ordering

    NASA Astrophysics Data System (ADS)

    Jackson, Mike; Bowles, Julie A.

    2014-11-01

    ashes, and tuffs from Mt. St. Helens and from Novarupta contain two principal forms of titanomagnetite: homogeneous grains with Curie temperatures in the range 350-500°C and oxyexsolved grains with similar bulk composition, containing ilmenite lamellae and having Curie temperatures above 500°C. Thermomagnetic analyses and isothermal annealing experiments in combination with stratigraphic settings and thermal models show that emplacement temperatures and cooling history may have affected the relative proportions of homogeneous and exsolved grains and have clearly had a strong influence on the Curie temperature of the homogeneous phase. The exsolved grains are most common where emplacement temperatures exceeded 600°C, and in laboratory experiments, heating to over 600°C in air causes the homogeneous titanomagnetites to oxyexsolve rapidly. Where emplacement temperatures were lower, Curie temperatures of the homogeneous grains are systematically related to overburden thickness and cooling timescales, and thermomagnetic curves are generally irreversible, with lower Curie temperatures measured during cooling, but little or no change is observed in room temperature susceptibility. We interpret this irreversible behavior as reflecting variations in the degree of cation ordering in the titanomagnetites, although we cannot conclusively rule out an alternative interpretation involving fine-scale subsolvus unmixing. Short-range ordering within the octahedral sites may play a key role in the observed phenomena. Changes in the Curie temperature have important implications for the acquisition, stabilization, and retention of natural remanence and may in some cases enable quantification of the emplacement temperatures or cooling rates of volcanic units containing homogeneous titanomagnetites.

  2. Effect of photochemical models on calculated equilibria and cooling rates in the stratosphere

    NASA Technical Reports Server (NTRS)

    Blake, D.; Lindzen, R. S.

    1973-01-01

    The determination of the relaxation time of a temperature perturbation in the stratosphere must take into account the effects of the absorption of solar energy by ozone, while the ozone density itself is dependent on temperature. A photochemical model, consisting of continuity equations for each of 29 constituents with reaction rates and adjustment times, is used to obtain the vertical distribution of ozone. The altitude range from 35 to 60 km in non-Arctic regions is shown to be in approximate joint radiative-photochemical equilibrium. The temperature and ozone distributions are thus well buffered. Modest changes in ozone and temperature were calculated on the basis of this model from large changes in cooling rates and reaction rates, and the results are shown to be more in line with actual observations. The importance of estimating the mixing ratios for NO and H2O is emphasized.

  3. Cooling rate dependent biophysical and viability response shift with attachment state in human dermal fibroblast cells.

    PubMed

    Choi, Jeunghwan; Bischof, John C

    2011-12-01

    While studies on the freezing of cells in suspension have been carried out extensively, corresponding studies with cells in the attached state and in tissue or tissue-equivalents are less developed. As attachment is a hallmark of the tissue state it is important to understand its impact on biophysics and viability to better apply freezing towards tissue preservation. The current study reports on observed biophysical response changes observed during freezing human dermal fibroblasts in suspension, attached cell, and fibrin tissue-equivalent models. Specifically, intracellular ice formation is shown to increase and dehydration is inferred to increase from suspension to attached systems. Biophysical model parameters fit to these experimental observations reflect the higher kinetics in the attached state. Post-thaw viability values from fast cooling rates were higher for suspension systems, and correlated well with the amount of IIF observed. On the other hand, viability values from slow cooling rates were higher for attached systems, although the degree of dehydration was predicted to be comparable to suspension cells. This disconnect between biophysics and viability predictions at slow rates clearly requires further investigation as it runs counter to our current understanding of dehydration injury in cells. This may suggest a possible protective effect of the attachment state on cell systems.

  4. Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dyanmics

    SciTech Connect

    Lane, J. Matthew D.

    2015-07-22

    We have conducted extremely long molecular dynamics simulations of glasses to microsecond times, which close the gap between experimental and atomistic simulation time scales by two to three orders of magnitude. The static, thermal, and structural properties of silica glass are reported for glass cooling rates down to 5×109 K/s and viscoelastic response in silica melts and glasses are studied over nine decades of time. We finally present results from relaxation of hydrostatic compressive stress in silica and show that time-temperature superposition holds in these systems for temperatures from 3500 to 1000 K.

  5. Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dyanmics

    DOE PAGES

    Lane, J. Matthew D.

    2015-07-22

    We have conducted extremely long molecular dynamics simulations of glasses to microsecond times, which close the gap between experimental and atomistic simulation time scales by two to three orders of magnitude. The static, thermal, and structural properties of silica glass are reported for glass cooling rates down to 5×109 K/s and viscoelastic response in silica melts and glasses are studied over nine decades of time. We finally present results from relaxation of hydrostatic compressive stress in silica and show that time-temperature superposition holds in these systems for temperatures from 3500 to 1000 K.

  6. Effect of Warm Deformation Parameters and Cooling Rates on the Recrystallization Transformation Microstructure in 40Cr Steel

    NASA Astrophysics Data System (ADS)

    Hu, C. L.; Zhao, Z.; Gong, A. J.; Shi, W. B.

    2015-01-01

    The effect of warm deformation parameters and cooling rates on transformation of the microstructure of 40Cr steel was investigated using both single- and double-pass compression tests. The compression tests were performed at temperatures ranging from 800 to 700 °C followed by controlled cooling at rates from 0.1 to 5 °C/s. All of the final transformation microstructures were observed by optical microscopy, and they were mainly composed of ferritic and pearlitic microstructures. For further quantitative analysis, a program based on image processing technology was developed to automatically calculate the volume fractions of ferrite and pearlite. After qualitative and quantitative analysis of the final microstructures, the results showed the following. The ferrite volume fraction significantly increased with increasing strain for the same deformation temperature. The strain rate had almost no effect on the ferrite fraction at the lower cooling rates. The ferrite fraction markedly increased with increasing strain rate when the cooling rate was greater than 1 °C/s. The ferrite fractions after single- and double-pass compression were 27-49 and 24-43% for a total strain of 0.7. The cooling rate after deformation had a remarkable effect on the microstructure morphology, and the ferrite volume fraction significantly decreased with increasing cooling rate.

  7. Effect of cooling rate on timing and dynamics of crystallization within a man-made magma body

    SciTech Connect

    Dunbar, N.W.; Jacobs, G.K.; Naney, M.T. )

    1992-01-01

    A 1.3 [times] 10[sup 7] g, 3 m diameter, hemispheric-shaped, man-made mafic melt produced by inductance heating was allowed to cool naturally, dropping from a maximum temperature of 1,500 C to 500 C in 6 days. The cooled melt was found to be almost completely crystalline, and is composed dominantly of unzoned pyroxene and plagioclase. A thermal arrest, a 20 hr period of constant temperature (1,140 C) observed during cooling resulted from the release of latent heat during crystallization. However, crystallization within the central part of the melt probably began at a higher temperature, as indicated by thermal perturbations between 1,300 C and 1,140 C. Comparison of results from simple conductive cooling models with the observed cooling curves influenced by latent heat input allows estimates of the timing of crystalline growth. Growth rates for plagioclase and pyroxene are estimated to range between 10[sup [minus]5] and 10[sup [minus]6] cm/sec. Although the melt was physically, chemically, and thermally homogeneous at the time that cooling was initiated, the crystal morphology and composition varies systematically with distance from the edge of the melt, presumably as a function of cooling rate and degree of undercooling at the time that crystallization was initiated. Crystals near the edge of the melt, where cooling was most rapid are characterized by disequilibrium skeletal or spherulitic morphologies. With increased proximity to the interior, and progressively slower cooling rates, crystal morphology grade from chain-like to lath-like, and finally to tabular in the slowest-cooled areas. The chemical composition of the diopsidic pyroxene also varies as function of growth rate. Crystals that grew near the edge of the melt are enriched with respect to Al, and depleted with respect to Mg as compared to crystals from the central area.

  8. Diffusively cooled thin-sheath high-repetition-rate TEA and TEMA lasers

    NASA Astrophysics Data System (ADS)

    Yatsiv, Shaul; Gabay, Amnon; Sintov, Yoav

    1993-05-01

    Transverse electric atmospheric (TEA), or multi atmospheric (TEMA) lasers deliver intense short laser pulses of considerable energies. Recurrent high repetition rate pulse trains afford substantial average power levels. In a high rep-rate operation the gas flows across the cavity and is externally cooled to maintain a reasonably low temperature. The gas flow gear and heat exchanger are bulky and costly. In this work we present a repetitively pulsed TEA or TEMA laser that combines energy and peak power features in an individual pulse with the substantial average power levels of a pulse train in a thin layer of gas. Excess heat is disposed of, by conduction through the gas, to cooled enclosing walls. The gas does not flow. The method applies to vibrational transition molecular lasers in the infrared, where elevated temperatures are deleterious to the laser operation. The gist of the method draws on the law that heat conductivity in gases does not depend on their pressure. The fact lends unique operational flexibility and compactness, desirable for industrial and research purposes.

  9. DIRECT EVIDENCE FOR CONDENSATION IN THE EARLY SOLAR SYSTEM AND IMPLICATIONS FOR NEBULAR COOLING RATES

    SciTech Connect

    Berg, T.; Maul, J.; Schoenhense, G.; Marosits, E.; Hoppe, P.; Ott, U.; Palme, H.

    2009-09-10

    We have identified in an acid resistant residue of the carbonaceous chondrite Murchison a large number (458) of highly refractory metal nuggets (RMNs) that once were most likely hosted by Ca,Al-rich inclusions (CAIs). While osmium isotopic ratios of two randomly selected particles rule out a presolar origin, the bulk chemistry of 88 particles with sizes in the submicron range determined by energy dispersive X-ray (EDX) spectroscopy shows striking agreement with predictions of single-phase equilibrium condensation calculations. Both chemical composition and morphology strongly favor a condensation origin. Particularly important is the presence of structurally incompatible elements in particles with a single-crystal structure, which also suggests the absence of secondary alteration. The metal particles represent the most pristine early solar system material found so far and allow estimation of the cooling rate of the gaseous environment from which the first solids formed by condensation. The resulting value of 0.5 K yr{sup -1} is at least 4 orders of magnitude lower than the cooling rate of molten CAIs. It is thus possible, for the first time, to see through the complex structure of most CAIs and infer the thermal history of the gaseous reservoir from which their components formed by condensation.

  10. A rapid heating and cooling rate dilatometer for measuring thermal expansion in dental porcelain.

    PubMed

    Twiggs, S W; Searle, J R; Ringle, R D; Fairhurst, C W

    1989-09-01

    Herein we describe a dilatometer that consists of a low-mass infrared furnace for rapid heating or cooling, an optical pyrometer, and a laser interferometer. The dilatometer facilitates observations of thermal expansion at rates comparable with those in dental laboratory practice over the temperature range necessary for comparison of thermal expansion of dental porcelain and alloy. Examples of thermal expansion data obtained at a 600 degrees C/min heating rate on NIST SRM 710 glass and dental porcelain are reported. To a limited extent, thermal expansion data above the glass-transition temperature range of dental porcelain were obtained. A shift of the glass-transition temperature range to higher temperatures was observed for both materials, compared with data obtained at 20 degrees C/min. PMID:2778175

  11. An improved thermoregulatory model for cooling garment applications with transient metabolic rates

    NASA Astrophysics Data System (ADS)

    Westin, Johan K.

    Current state-of-the-art thermoregulatory models do not predict body temperatures with the accuracies that are required for the development of automatic cooling control in liquid cooling garment (LCG) systems. Automatic cooling control would be beneficial in a variety of space, aviation, military, and industrial environments for optimizing cooling efficiency, for making LCGs as portable and practical as possible, for alleviating the individual from manual cooling control, and for improving thermal comfort and cognitive performance. In this study, we adopt the Fiala thermoregulatory model, which has previously demonstrated state-of-the-art predictive abilities in air environments, for use in LCG environments. We validate the numerical formulation with analytical solutions to the bioheat equation, and find our model to be accurate and stable with a variety of different grid configurations. We then compare the thermoregulatory model's tissue temperature predictions with experimental data where individuals, equipped with an LCG, exercise according to a 700 W rectangular type activity schedule. The root mean square (RMS) deviation between the model response and the mean experimental group response is 0.16°C for the rectal temperature and 0.70°C for the mean skin temperature, which is within state-of-the-art variations. However, with a mean absolute body heat storage error 3¯ BHS of 9.7 W˙h, the model fails to satisfy the +/-6.5 W˙h accuracy that is required for the automatic LCG cooling control development. In order to improve model predictions, we modify the blood flow dynamics of the thermoregulatory model. Instead of using step responses to changing requirements, we introduce exponential responses to the muscle blood flow and the vasoconstriction command. We find that such modifications have an insignificant effect on temperature predictions. However, a new vasoconstriction dependency, i.e. the rate of change of hypothalamus temperature weighted by the

  12. Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Knopf, D. A.

    2015-05-01

    Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature (T) and relative humidity (RH) at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling rate dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nuclei (IN) all have the same IN surface area (ISA), however the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses physically observable parameters including the total number of droplets (Ntot) and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets, droplets in a continuous flow diffusion chamber (CFDC), the Leipzig aerosol cloud interaction simulator (LACIS), and the aerosol interaction and dynamics in the atmosphere (AIDA) cloud chamber. Observed time dependent isothermal frozen fractions exhibiting non-exponential behavior with time can be readily explained by this model considering varying ISA. An

  13. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-05-01

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1˜2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  14. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    SciTech Connect

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-05-22

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  15. Body size, but not cooling rate, affects supercooling points in the red imported fire ant, Solenopsis invicta.

    PubMed

    Hahn, Daniel A; Martin, Adam R; Porter, Sanford D

    2008-10-01

    The level of an animal's stress resistance is set by multiple intrinsic physiological and extrinsic environmental parameters. Body size is a critical intrinsic parameter that affects numerous fitness-related organismal traits including fecundity, survival, mating success, and stress resistance. The rate of cooling is a critical extrinsic environmental factor that can affect thermal stress resistance. Workers of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), display considerable variation in adult body size. Therefore, developing ecologically realistic models of thermotolerance in this species requires a consideration of body size. We tested the hypothesis that body size and cooling rate would interact to set the supercooling point in fire ant workers by exposing workers of a range of body sizes to three different cooling regimens: a very fast ramp of -10 degrees C/min, an intermediate ramp of -1 degrees C/min, and an ecologically relevant slow ramp of -0.1 degrees C/min. Specifically, we asked whether large workers were more susceptible to differences in cooling rate than smaller workers. We found that body size had a considerable effect on supercooling point with the largest workers freezing at a temperature approximately 3 degrees C higher than the smallest workers. Cooling rate had a very small effect on supercooling point, and there was no interaction between the two factors. Therefore, the allometry of supercooling points across the range of worker body sizes does not change with cooling rate.

  16. Supercooling effects in Cu-10 wt pct Co alloys solidified at different cooling rates

    NASA Technical Reports Server (NTRS)

    Munitz, A.; Elder-Randall, S. P.; Abbaschian, R.

    1992-01-01

    Electromagnetic levitation and electron beam surface melting were employed to study the effects of supercooling and cooling rate on the solidification of Cu-10 wt pct Co alloys. Two major effects were observed in the supercooled alloys: the nucleation of a metastable copper-rich phase which contains 13 wt pct to 20 wt pct Co in samples supercooled between 105 and 150 K and liquid phase separation which occurs in samples supercooled 150 K or more. The microstructure of the electron beam melted surfaces consisted of very fine spheres which were similar to those of the sample supercooled more than 150 K but with a refined microstructure. The results indicate that a dynamic bulk supercooling of 150 K may exist in the molten pool during the solidification of electron beam melted surfaces.

  17. Pregnancy rates after artificial insemination with cooled stallion spermatozoa either with or without single layer centrifugation.

    PubMed

    Morrell, J M; Richter, J; Martinsson, G; Stuhtmann, G; Hoogewijs, M; Roels, K; Dalin, A-M

    2014-11-01

    A successful outcome after artificial insemination with cooled semen is dependent on many factors, the sperm quality of the ejaculate being one. Previous studies have shown that spermatozoa with good motility, normal morphology, and good chromatin integrity can be selected by means of colloid centrifugation, particularly single layer centrifugation (SLC) using species-specific colloids. The purpose of the present study was to conduct an insemination trial with spermatozoa from "normal" ejaculates, i.e., from stallions with no known fertility problem, to determine whether the improvements in sperm quality seen in SLC-selected sperm samples compared with uncentrifuged controls in laboratory tests are reflected in an increased pregnancy rate after artificial insemination. In a multicentre study, SLC-selected sperm samples and uncentrifuged controls from eight stallions were inseminated into approximately 10 mares per treatment per stallion. Ultrasound examination was carried out approximately 16 days after insemination to detect an embryonic vesicle. The pregnancy rates per cycle were 45% for controls and 69% for SLC-selected sperm samples, which is statistically significant (P < 0.0018). Thus, the improvement in sperm quality reported previously for SLC-selected sperm samples is associated with an increase in pregnancy rate, even for ejaculates from stallions with no known fertility problem.

  18. Dendritic Growth and Microstructure Evolution with Different Cooling Rates in Ti48Al2Cr2Nb Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Hu, Rui; Zhang, Tiebang; Kou, Hongchao; Wang, Jun; Yang, Guang; Li, Jinshan

    2016-01-01

    The influence of cooling rates on the dendritic growth and microstructure evolution of Ti48Al2Cr2Nb alloy is studied by electromagnetic levitation combined with copper mold casting. The different cooling rates of the conical as-cast sample with diameters from 4.7 to 0.8 mm were calculated by ANSYS software. The results show that primary dendrite arm spacing decreases with increase in cooling rate. Peritectic transformation (L + β → α) and the transformation of α → (α2 + γ) are restrained at cooling rate of 2.3 × 104 K s-1. With further increase in cooling rate (2.6 × 104 K s-1), a fine and homogeneous microstructure can be observed in the conical casting sample with the diameter of 0.8 mm. It consists of a large amount of massive γ phase, lath-like γ phase, and only few lamellar structures (α2 + γ). The formation of the microstructure in the alloy is attributed to the strong chilling, giving rise to the high undercooling and the high dislocation density during rapid solidification.

  19. Effect of cooling rate and gelatin concentration on the microstructural and mechanical properties of ice template gelatin scaffolds.

    PubMed

    Arabi, Neda; Zamanian, Ali

    2013-01-01

    In the current study, a controlled unidirectional freeze casting method was employed to fabricate highly porous gelatin scaffolds. Different gelatin concentrations of 1, 3, and 5 wt% were dissolved in distilled water, and the constant value of glutaraldehyde cross-linking agent (0.5 wt%) was added to the solution. Then, the solutions freeze casted at different cooling rates of 1, 3, and 6°C/Min and freeze dried. Finally, pore morphology, mechanical properties, and water adsorption characteristics of scaffolds were assessed. Results showed that the increase in gelatin concentration caused the pore shapes to change from oblate and polygon to almost round but the cooling rate had no obvious effect on pore morphology. Compressive strength of the scaffolds improved as a function of increase in cooling rate and gelatin concentration from 20 to 1,150 kPa. The value of water adsorption was decreased with augmentation in gelatin concentration and cooling rate in the range of 2,000%-500%. Therefore, this study suggests that the use of a controllable freeze casting method and cooling rate can tailor the pore morphology, mechanical properties, and water adsorption of gelatin scaffolds and could be a novel approach to avoid the use of a toxic dose of a cross-linking agent like glutaraldehyde.

  20. On the Lower Limit of Chondrule Cooling Rates: The Significance of Iron Loss in Dynamic Crystallization Experiments

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Connolly, Harold C., Jr.; Lofgren, Gary E.

    1998-01-01

    It is unlikely that the presence of chondrules, and thus their formation, within the protoplanetary nebula would be predicted if it were not for their ubiquitous presence in most chondritic meteorites. The study of these enigmatic, igneous objects has a direct influence on how meteoritic and solar system researchers model the processes operating and the materials present within our protoplanetary nebula. Key to understanding chondrule formation is a determination of constraints on their thermal histories. The three important variables in this history are their peak melting temperatures, the duration of their melting at peak temperatures, and the rate at which these object cool. Although these three variables are interdependent, it is cooling rate that provides the most powerful constraint. Cooling rate has a direct affect on the development of both crystal morphology and the elemental distributions within these grains. To date, experiments have indicated that chondrule cooling rates are in the range of 10's to 100's of degrees per hour for porphyritic chondrules (the most abundant type). The cooling rate for radial and barred chondrules is thought to be more rapid. To generate these cooling rates (rapid relative to the cooling of the nebula as a whole, but slow compared to simple black body radiation) the environment of chondrule formation must have been localized, and the abundance of solid materials must have been greatly enhanced above a gas of solar composition. Thus accurate determinations of chondrule cooling rates is critical in understanding both their formation and the nebular environment in which they formed. In a quest to more accurately determine the lower limit on cooling rates and to determine in more detail the effects of Fe loss from a molten sample to Pt wire loops, Weinbruch et al. have explored this issue experimentally and reevaluated the findings of Radomsky and Hewins in light of their new results. The basic conclusions of their paper are an

  1. Impact of Cooling Rate-Induced Recrystallization on High G Mechanical Shock and Thermal Cycling in Sn-Ag-Cu Solder Interconnects

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu; Bieler, Thomas R.; Kim, Choong-Un

    2016-01-01

    The mechanical stability and thermo-mechanical fatigue performance of solder joints with low silver content Sn-1.0Ag-0.5Cu (wt.%) (SAC105) alloy based on different cooling rates are investigated in high G level shock environment and thermal cycling conditions. The cooling rate-controlled samples ranging from 1°C/min to 75°C/min cooling rate, not only show differences in microstructure, where a fine poly-granular microstructure develops in the case of fast cooling versus normal cooling, but also show various shock performances based on the microstructure changes. The fast cooling rate improves the high G shock performance by over 90% compared to the normal cooled SAC105 alloy air-cooling environment commonly used after assembly reflow. The microstructure effect on thermal cycling performance is also discussed, which is analyzed based on the Sn grain orientation, interconnect stability, and solder joint bulk microstructure.

  2. A Gradient in Cooling Rate Beneath the Moho at the Oman Ophiolite: Fresh Insights into Cooling Processes at Mid-Ocean Ridges from REE-Based Thermometry

    NASA Astrophysics Data System (ADS)

    Dygert, N. J.; Kelemen, P. B.; Liang, Y.

    2015-12-01

    The Wadi Tayin massif in the southern Oman ophiolite has a more than 10 km thick mantle section and is believed to have formed in a mid-ocean ridge like environment with an intermediate to fast spreading rate. Previously, [1] used major element geothermometers to investigate spatial variations in temperatures recorded in mantle peridotites and observed that samples near the paleo-Moho have higher closure temperatures than samples at the base of the mantle section. Motivated by these observations, we measured major and trace elements in orthopyroxene and clinopyroxene in peridotites from depths of ~1-8km beneath the Moho to determine closure temperatures of REE in the samples using the REE-in-two-pyroxene thermometer [2]. Clinopyroxene are depleted in LREE and have REE concentrations that vary depending on distance from the Moho. Samples nearer the Moho have lower REE concentrations than those deeper in the section (e.g., chondrite normalized Yb ranges from ~1.5 at the Moho to 4 at 8km depth), consistent with near fractional melting along a mantle adiabat. Orthopyroxene are highly depleted in LREE but measurements of middle to heavy REE have good reproducibility. We find that REE-in-two-pyroxene temperatures decrease with increasing distance from the Moho, ranging from 1325±10°C near the Moho to 1063±24°C near the base of the mantle section. Using methods from [3], we calculate cooling rates of >1000°C/Myr near the Moho, dropping to rates of <10°C/Myr at the bottom of the section. The faster cooling rate is inconsistent with conductive cooling models. Fast cooling of the mantle lithosphere could be facilitated by infiltration of seawater to or beneath the petrologic Moho. This can explain why abyssal peridotites from ultra-slow spreading centers (which lack a crustal section) have cooling rates comparable to those of Oman peridotites [3]. [1] Hanghøj et al. (2010), JPet 51(1-2), 201-227. [2] Liang et al. (2013), GCA 102, 246-260. [3] Dygert & Liang (2015

  3. Heart Rate Variability in Sleeping Preterm Neonates Exposed to Cool and Warm Thermal Conditions

    PubMed Central

    Stéphan-Blanchard, Erwan; Chardon, Karen; Léké, André; Delanaud, Stéphane; Bach, Véronique; Telliez, Frédéric

    2013-01-01

    Sudden infant death syndrome (SIDS) remains the main cause of postneonatal infant death. Thermal stress is a major risk factor and makes infants more vulnerable to SIDS. Although it has been suggested that thermal stress could lead to SIDS by disrupting autonomic functions, clinical and physiopathological data on this hypothesis are scarce. We evaluated the influence of ambient temperature on autonomic nervous activity during sleep in thirty-four preterm neonates (mean ± SD gestational age: 31.4±1.5 weeks, postmenstrual age: 36.2±0.9 weeks). Heart rate variability was assessed as a function of the sleep stage at three different ambient temperatures (thermoneutrality and warm and cool thermal conditions). An elevated ambient temperature was associated with a higher basal heart rate and lower short- and long-term variability in all sleep stages, together with higher sympathetic activity and lower parasympathetic activity. Our study results showed that modification of the ambient temperature led to significant changes in autonomic nervous system control in sleeping preterm neonates. The latter changes are very similar to those observed in infants at risk of SIDS. Our findings may provide greater insight into the thermally-induced disease mechanisms related to SIDS and may help improve prevention strategies. PMID:23840888

  4. Heart rate variability in sleeping preterm neonates exposed to cool and warm thermal conditions.

    PubMed

    Stéphan-Blanchard, Erwan; Chardon, Karen; Léké, André; Delanaud, Stéphane; Bach, Véronique; Telliez, Frédéric

    2013-01-01

    Sudden infant death syndrome (SIDS) remains the main cause of postneonatal infant death. Thermal stress is a major risk factor and makes infants more vulnerable to SIDS. Although it has been suggested that thermal stress could lead to SIDS by disrupting autonomic functions, clinical and physiopathological data on this hypothesis are scarce. We evaluated the influence of ambient temperature on autonomic nervous activity during sleep in thirty-four preterm neonates (mean ± SD gestational age: 31.4±1.5 weeks, postmenstrual age: 36.2±0.9 weeks). Heart rate variability was assessed as a function of the sleep stage at three different ambient temperatures (thermoneutrality and warm and cool thermal conditions). An elevated ambient temperature was associated with a higher basal heart rate and lower short- and long-term variability in all sleep stages, together with higher sympathetic activity and lower parasympathetic activity. Our study results showed that modification of the ambient temperature led to significant changes in autonomic nervous system control in sleeping preterm neonates. The latter changes are very similar to those observed in infants at risk of SIDS. Our findings may provide greater insight into the thermally-induced disease mechanisms related to SIDS and may help improve prevention strategies. PMID:23840888

  5. A new estimate of the chondrule cooling rate deduced from an analysis of compositional zoning of relict olivine

    SciTech Connect

    Miura, H.; Yamamoto, T.

    2014-03-01

    Compositional zoning in chondrule phenocrysts records the crystallization environments in the early solar nebula. We modeled the growth of olivine phenocrysts from a silicate melt and proposed a new fractional crystallization model that provides a relation between the zoning profile and the cooling rate. In our model, we took elemental partitioning at a growing solid-liquid interface and time-dependent solute diffusion in the liquid into consideration. We assumed a local equilibrium condition, namely, that the compositions at the interface are equal to the equilibrium ones at a given temperature. We carried out numerical simulations of the fractional crystallization in one-dimensional planar geometry. The simulations revealed that under a constant cooling rate the growth velocity increases exponentially with time and a linear zoning profile forms in the solid as a result. We derived analytic formulae of the zoning profile, which reproduced the numerical results for wide ranges of crystallization conditions. The formulae provide a useful tool to estimate the cooling rate from the compositional zoning. Applying the formulae to low-FeO relict olivine grains in type II porphyritic chondrules observed by Wasson and Rubin, we estimate the cooling rate to be ∼200-2000 K s{sup –1}, which is greater than that expected from furnace-based experiments by orders of magnitude. Appropriate solar nebula environments for such rapid cooling conditions are discussed.

  6. Modeling of the cooling rate effect on the residual stress formation in the cantala fiber/recycled HDPE composites

    NASA Astrophysics Data System (ADS)

    Probotinanto, Yosafat C.; Raharjo, Wijang W.; Budiana, Eko P.

    2016-03-01

    Residual stress has great influence on the mechanical properties of polymer composites. Therefore, its formation during the manufacturing process needs to be investigated. The aim of this study is to investigate the influences of cooling rate on the residual stress distribution of the cantala/rHDPE composite by simulation. The simulation was done by using a SOLID227 element type of ANSYS. The cooling rates that used in this study are 0.5°C/minute, 1°C/minute, and 60°C/minute. The values of the residual stress correspond to the increasing of the cooling rate are 1171.31 kPa, 1171.42 kPa, 1172.36 kPa. In the radial direction, the residual stress was tensile inside the fibers, while in the longitudinal direction, the tensile residual stress occurred in the matrix zones and compressive in the fiber zones.

  7. Cooling rates dependence of medium-range order development in C u64 .5Z r35 .5 metallic glass

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Zhang, F.; Wang, C. Z.; Mendelev, M. I.; Kramer, M. J.; Ho, K. M.

    2015-02-01

    The atomic structure of metallic glasses (MGs) plays an important role in their properties. Numerous molecular dynamics (MD) simulations have revealed icosahedral short-range order (ISRO) as a dominant motif in Cu-Zr metallic glasses. However, the cooling rates utilized in most of the MD simulations (usually on the order of 1010 -13K /s ) can be too high to allow the structure to relax into the actual structures. By performing a long sub-Tg annealing of the C u64.5Z r35.5 alloy model at 700 K up to 2.0 μ s using MD simulations, we systematically address the evolution of medium-range order (MRO) as the cooling rates in MD simulations approach the experimental cooling rates (usually 103 -6K /s ). By reducing the effective cooling rates to as low as 2.8 ×107K /s , we found a significant enhancement of the ISRO and Bergman-type MRO. Comparing to the widely used face-, edge-, or vertex-sharing icosahedra, we propose that the Bergman-type MRO is a much more unambiguous metric to characterize the MRO in Cu-Zr MGs. By analyzing the network formed by interpenetrating icosahedra using the graphical theory, we show that the degree of interpenetration of the icosahedra centers increases with decreasing cooling rates. The network becomes aggressively assortative, indicating that higher degree nodes tend to cluster and form backbones in the MG. All these results show that the networks in the models prepared using lower cooling rates strongly deviate from a stringlike morphology.

  8. Effect of Cooling Rate on Phase Transformations in a High-Strength Low-Alloy Steel Studied from the Liquid Phase

    NASA Astrophysics Data System (ADS)

    Dorin, Thomas; Stanford, Nicole; Taylor, Adam; Hodgson, Peter

    2015-12-01

    The phase transformation and precipitation in a high-strength low-alloy steel have been studied over a large range of cooling rates, and a continuous cooling transformation (CCT) diagram has been produced. These experiments are unique because the measurements were made from samples cooled directly from the melt, rather than in homogenized and re-heated billets. The purpose of this experimental design was to examine conditions pertinent to direct strip casting. At the highest cooling rates which simulate strip casting, the microstructure was fully bainitic with small regions of pearlite. At lower cooling rates, the fraction of polygonal ferrite increased and the pearlite regions became larger. The CCT diagram and the microstructural analysis showed that the precipitation of NbC is suppressed at high cooling rates, and is likely to be incomplete at intermediate cooling rates.

  9. Effect of cooling rate on leucite volume fraction in dental porcelains.

    PubMed

    Mackert, J R; Evans, A L

    1991-02-01

    Prasad et al. (1988) have shown that slow cooling of dental porcelain produces increases in thermal expansion sufficient to make a compatible metal-porcelain system incompatible. The present study was undertaken to determine whether the increase in porcelain thermal expansion might be attributable to crystallization of additional leucite during slow cooling of the porcelain. Eight x-ray diffraction specimens for each of six commercial dental porcelains and for the Component No. 1 frit of the Weinstein and Weinstein (1962) and Weinstein et al. (1962) patents were fabricated and divided into two groups. Specimens in the first group (termed fast-cooled) were cooled in the conventional manner by removing them from the furnace at the maximum firing temperature immediately into room air. Specimens in the second group (termed slow-cooled) were cooled slowly by interrupting power to the furnace muffle and allowing them to cool inside the closed furnace. Quantitative x-ray diffraction was performed on the fast- and slow-cooled porcelain specimens with standards containing leucite volume fractions of 0.111, 0.223, 0.334, and 0.445. Unpaired, one-tailed t tests were performed on the fast- and slow-cool data, and a significant increase (p less than 0.05) in the amount of leucite (as a function of the slow cooling) was found for each of the porcelains. The increases in the leucite volume fractions resulting from the slow cooling ranged from a low of 8.5% to a high of 55.8%, with an average increase of 26.9%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1991871

  10. The effect of ultrasound irradiation on the convective heat transfer rate during immersion cooling of a stationary sphere.

    PubMed

    Kiani, Hossein; Sun, Da-Wen; Zhang, Zhihang

    2012-11-01

    It has been proven that ultrasound irradiation can enhance the rate of heat transfer processes. The objective of this work was to study the heat transfer phenomenon, mainly the heat exchange at the surface, as affected by ultrasound irradiation around a stationary copper sphere (k=386W m(-1)K(-1), C(p)=384J kg(-1)K(-1), ρ=8660kg m(-3)) during cooling. The sphere (0.01m in diameter) was immersed in an ethylene glycol-water mixture (-10°C) in an ultrasonic cooling system that included a refrigerated circulator, a flow meter, an ultrasound generator and an ultrasonic bath. The temperature of the sphere was recorded using a data logger equipped with a T-type thermocouple in the center of the sphere. The temperature of the cooling medium was also monitored by four thermocouples situated at different places in the bath. The sphere was located at different positions (0.02, 0.04 and 0.06m) above the transducer surface of the bath calculated considering the center of the sphere as the center of the reference system and was exposed to different intensities of ultrasound (0, 120, 190, 450, 890, 1800, 2800, 3400 and 4100W m(-2)) during cooling. The frequency of the ultrasound was 25kHz. It was demonstrated that ultrasound irradiation can increase the rate of heat transfer significantly, resulting in considerably shorter cooling times. Higher intensities caused higher cooling rates, and Nu values were increased from about 23-27 to 25-108 depending on the intensity of ultrasound and the position of the sphere. However, high intensities of ultrasound led to the generation of heat at the surface of the sphere, thus limiting the lowest final temperature achieved. An analytical solution was developed considering the heat generation and was fitted to the experimental data with R(2) values in the range of 0.910-0.998. Visual observations revealed that both cavitation and acoustic streaming were important for heat transfer phenomenon. Cavitation clouds at the surface of the sphere

  11. The effect of ultrasound irradiation on the convective heat transfer rate during immersion cooling of a stationary sphere.

    PubMed

    Kiani, Hossein; Sun, Da-Wen; Zhang, Zhihang

    2012-11-01

    It has been proven that ultrasound irradiation can enhance the rate of heat transfer processes. The objective of this work was to study the heat transfer phenomenon, mainly the heat exchange at the surface, as affected by ultrasound irradiation around a stationary copper sphere (k=386W m(-1)K(-1), C(p)=384J kg(-1)K(-1), ρ=8660kg m(-3)) during cooling. The sphere (0.01m in diameter) was immersed in an ethylene glycol-water mixture (-10°C) in an ultrasonic cooling system that included a refrigerated circulator, a flow meter, an ultrasound generator and an ultrasonic bath. The temperature of the sphere was recorded using a data logger equipped with a T-type thermocouple in the center of the sphere. The temperature of the cooling medium was also monitored by four thermocouples situated at different places in the bath. The sphere was located at different positions (0.02, 0.04 and 0.06m) above the transducer surface of the bath calculated considering the center of the sphere as the center of the reference system and was exposed to different intensities of ultrasound (0, 120, 190, 450, 890, 1800, 2800, 3400 and 4100W m(-2)) during cooling. The frequency of the ultrasound was 25kHz. It was demonstrated that ultrasound irradiation can increase the rate of heat transfer significantly, resulting in considerably shorter cooling times. Higher intensities caused higher cooling rates, and Nu values were increased from about 23-27 to 25-108 depending on the intensity of ultrasound and the position of the sphere. However, high intensities of ultrasound led to the generation of heat at the surface of the sphere, thus limiting the lowest final temperature achieved. An analytical solution was developed considering the heat generation and was fitted to the experimental data with R(2) values in the range of 0.910-0.998. Visual observations revealed that both cavitation and acoustic streaming were important for heat transfer phenomenon. Cavitation clouds at the surface of the sphere

  12. Effect of cooling rate and cryoprotectant concentration on intracellular ice formation of small abalone (Haliotis diversicolor) eggs.

    PubMed

    Yang, Chiang-Yi; Yeh, Yu-Hui Flora; Lee, Po-Ting; Lin, Ta-Te

    2013-08-01

    The intracellular ice formation (IIF) behavior of Haliotis diversicolor (small abalone) eggs is investigated in this study, in relation to controlling the cooling rate and the concentration of dimethyl sulfoxide (DMSO). The IIF phenomena are monitored under a self-developed thermoelectric cooling (TEC) cryomicroscope system which can achieve accurate temperature control without the use of liquid nitrogen. The accuracy of the isothermal and ramp control is within ±0.5 °C. The IIF results indicate that the IIF of small abalone eggs is well suppressed at cooling rates of 1.5, 3, 7 and 12 °C/min with 2.0, 2.5, 3.0 and 4.0M DMSO in sea water. As 2.0M DMSO in sea water is the minimum concentration that has sufficient IIF suppression, it is selected as the suspension solution for the cryopreservation of small abalone eggs in order to consider the solution's toxicity effect. Moreover, IIF characteristics of the cumulative probability of IIF temperature distribution are shown to be well fitted by the Weibull probabilistic distribution. According to our IIF results and the Weibull distribution parameters, we conclude that cooling at 1.5 °C/min from 20 to -50 °C with 2.0M DMSO in sea water is more feasible than other combinations of cooling rates and DMSO concentrations in our experiments. Applying this protocol and observing the subsequent osmotic activity, 48.8% of small abalone eggs are osmotically active after thawing. In addition, the higher the cooling rate, the less chance of osmotically active eggs. A separate fertility test experiment, with a cryopreservation protocol of 1.5 °C/min cooling rate and 2.0M DMSO in sea water, achieves a hatching rate of 23.7%. This study is the first to characterize the IIF behavior of small abalone eggs in regard to the cooling rate and the DMSO concentration. The Weibull probabilistic model fitting in this study is an approach that can be applied by other researchers for effective cryopreservation variability estimation and

  13. Field drying rate differences amoung cool-season grasses harvested for hay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Making high-quality, cool-season grass hay is a challenge, due to the field drying time needed to reach the appropriate moisture content and the high probability of rain in the spring when hay is typically produced. This study was conducted to determine if cool-season grasses with different yield po...

  14. Influence of Cooling Rate on Phase Formationin Spray-Formed H13 Tool Steel

    SciTech Connect

    K. M. Mchugh; Y. Lin; Y. Zhou; E. J. Lavernia

    2006-04-01

    Spray forming is an effective way to process many tool steels into near-net-shape molds, dies and related tooling. The general approach involves depositing atomized droplets onto a refractory pattern in order to image the pattern’s features. The pattern is removed and the die is fitted into a standard holding fixture. This approach results in significant cost and lead-time savings compared to conventional machining, Spray-formed dies perform well in many industrial forming operations, oftentimes exhibiting extended die life over conventional dies. Care must be exercised when spray forming tool steel dies to minimize porosity and control the nature and distribution of phases and residual stresses. Selection of post-deposition heat treatment is important to tailor the die’s properties (hardness, strength, impact energy, etc.) for a particular application. This paper examines how the cooling rate and other processing parameters during spray processing and heat treatment of H13 tool steel influence phase formation. Results of case studies on spray-formed die performance in forging, extrusion and die casting, conducted by industry during production runs, will be described.

  15. Effect of Cooling Rate and Oxygen Fugacity on the Crystallization of the Queen Alexandra Range 94201 Martian Melt Composition

    NASA Technical Reports Server (NTRS)

    Koizumi, E.; Mikouchi, T.; McKay, G.; Schwandt, C.; Monkawa, A.; Miyamoto, M.

    2002-01-01

    Although many basaltic shergottites have been recently found in north African deserts, QUE94201 basaltic shergottite (QUE) is still important because of its particular mineralogical and petrological features. This meteorite is thought to represent its parent melt composition [1 -3] and to crystallize under most reduced condition in this group [1,4]. We performed experimental study by using the synthetic glass that has the same composition as the bulk of QUE. After homogenization for 48 hours at 1300 C, isothermal and cooling experiments were done under various conditions (e.g. temperature, cooling rates, and redox states). Our goals are (1) to verify that QUE really represents its parent melt composition, (2) to estimate a cooling rate of this meteorite, (3) to clarify the crystallization sequences of present minerals, and (4) to verity that this meteorite really crystallized under reduced condition.

  16. Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data

    NASA Astrophysics Data System (ADS)

    Hicks, A. K.; Mushotzky, R.

    2005-12-01

    We have analyzed XMM-Newton Optical Monitor UV (180-400 nm) data for a sample of 33 galaxies. Thirty are cluster member galaxies, and nine are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates between 8 and 525 Msolar yr-1. By comparing the ratio of UV to 2MASS J-band fluxes, we find a significant UV excess in many, but not all, cooling flow CCGs, consistent with several previous studies based on optical imaging data (McNamara & O'Connell Cardiel et al.; Crawford et al.). This UV excess is a direct indication of the presence of young massive stars and, therefore, recent star formation. Using the Starburst99 model of continuous star formation over a 900 Myr period, we derive star formation rates of 0.2-219 Msolar yr-1 for the cooling flow sample. For two-thirds of this sample, it is possible to equate Chandra/XMM cooling flow mass deposition rates with UV-inferred star formation rates, for a combination of starburst lifetime and IMF slope. This is a pilot study of the well-populated XMM UV cluster archive, and a more extensive follow-up study is currently underway.

  17. Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data

    NASA Technical Reports Server (NTRS)

    Hicks, A. K.; Mushotzky, R.

    2005-01-01

    We have analyzed XMM-Newton Optical Monitor (OM) UV (180-400 nm) data for a sample of 33 galaxies. 30 are cluster member galaxies, and nine of these are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates which span a range of 8 - 525 solar mass per year. By comparing the ratio of UV to 2MASS J band fluxes, we find a significant UV excess in many, but not all, cooling flow CCGs, a finding consistent with the outcome of previous studies based on optical imaging data (McNamara & O Connell 1989; Cardiel, Gorgas, & Aragon-Salamanca 1998; Crawford et al. 1999). This UV excess is a direct indication of the presence of young massive stars, and therefore recent star formation, in these galaxies. Using the Starburst99 spectral energy distribution (SED) model of continuous star formation over a 900 Myr period, we derive star formation rates of 0.2 - 219 solar mass per year for the cooling flow sample. For 2/3 of this sample it is possible to equate Chandra/XMM cooling flow mass deposition rates with UV inferred star formation rates, for a combination of starburst lifetime and IMF slope. This is a pilot study of the well populated XMM UV cluster archive and a more extensive follow up study is currently underway.

  18. Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data

    NASA Technical Reports Server (NTRS)

    Hicks, A. K.; Mushotzky, R.

    2006-01-01

    We have analyzed XMM-Newton Optical Monitor (OM) UV (180-400 nm) data for a sample of 33 galaxies. 30 are cluster member galaxies, and nine of these are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates which span a range of 8 - 525 Solar Mass/yr. By comparing the ratio of UV to 2MASS J band fluxes, we find a significant UV excess in many, but not all, cooling flow CCGs, a finding consistent with the outcome of previous studies based on optical imaging data (McNamara & O'Connell 1989; Cardiel, Gorgas, & Aragon-Salamanca 1998; Crawford et al. 1999). This UV excess is a direct indication of the presence of young massive stars, and therefore recent star formation, in these galaxies. Using the Starburst99 spectral energy distribution (SED) model of continuous star formation over a 900 Myr period, we derive star formation rates of 0.2 - 219 solar Mass/yr for the cooling flow sample. For 2/3 of this sample it is possible to equate Chandra/XMM cooling flow mass deposition rates with UV inferred star formation rates, for a combination of starburst lifetime and IMF slope. This is a pilot study of the well populated XMM UV cluster archive and a more extensive follow up study is currently underway.

  19. Cooling rate and thermal structure determined from progressive magnetization of the Dacite Dome at Mount St. Helens, Washington

    NASA Astrophysics Data System (ADS)

    Dzurisin, Daniel; Denlinger, Roger P.; Rosenbaum, Joseph G.

    1990-03-01

    Our study of a magnetic anomaly associated with the recently active dacite dome at Mount St. Helens suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool, magnetized carapace and flanking talus. The talus does not contribute to the anomaly because its constituent blocks are randomly oriented. Temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0.03±0.01 m/d from 1984 to 1986. Petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature, rather than subsequent changes in magnetization caused by further oxidation. Newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface. The cooling rate gradually declines for several weeks, and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward. The rate of internal convective heat loss through fractures varies with rainfall, snowmelt, and large-scale fracturing during subsequent eruptive episodes. In accordance with a model for solidification of the 1959 lava lake at Kilauea Iki, Hawaii, we picture the dome's magnetized carapace as being a two-phase, porous, convective zone separated from the nonmagnetized core of the dome by a thin, single-phase conductive zone. As a consequence of the heat balance between the conductive and convective zones, the blocking-temperature isotherm migrates inward at a relatively constant rate. If the dome remains inactive, the time scale for its complete magnetization is estimated to be 18-36 years, a forecast which can be refined by shallow drilling into the dome and by continuing studies of its growing magnetic anomaly.

  20. Cooling rate and thermal structure determined from progressive magnetization of the dacite dome at Mount St. Helens, Washington

    SciTech Connect

    Dzurisin, D. ); Denlinger, R.P. ); Rosenbaum, J.G. )

    1990-03-10

    The study suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool magnetized carapace and flanking talus. Temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0.03 {plus minus} 0.01 m/d from 1984 to 1986. Petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature, rather than subsequent changes in magetization caused by further oxidation. Newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface. The cooling rate gradually declines for several weeks, and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward. The rate of internal convective heat loss through fractures varies with rainfall, snowmelt, and large-scale fracturing during subsequent eruptive episodes. In accordance with a model for solidification of the 1959 lava lake at Kilauea Iki, Hawaii, the authors picture the dome's magnetized carapace as being a two-phase, porous, convective zone separated from the nonmagnetized core of the dome by a thin, single-phase conductive zone. As a consequence of the heat balance between the conductive and convective zones, the blocking-temperature isotherm migrates inward at a relatively constant rate. If the dome remains inactive, the time scale for its complete magnetization is estimated to be 18-36 years, a forecast which can be refined by shallow drilling into the dome and by continuing studies of its growing magnetic anomaly.

  1. Transpiration cooling of hypersonic blunt bodies with finite rate surface reactions

    NASA Technical Reports Server (NTRS)

    Henline, William D.

    1989-01-01

    The convective heat flux blockage to blunt body and hypersonic vehicles by transpiration cooling are presented. The general problem of mass addition to laminar boundary layers is reviewed. Results of similarity analysis of the boundary layer problem are provided for surface heat flux with transpiration cooling. Detailed non-similar results are presented from the numerical program, BLIMPK. Comparisons are made with the similarity theory. The effects of surface catalysis are investigated.

  2. Effect of Rolling Temperature and Ultrafast Cooling Rate on Microstructure and Mechanical Properties of Steel Plate

    NASA Astrophysics Data System (ADS)

    Ye, Qibin; Liu, Zhenyu; Yang, Yu; Wang, Guodong

    2016-07-01

    Microstructure can vary significantly through thickness after ultrafast cooling of rolled steel plates, impacting their mechanical properties. This study examined the microstructure, microstructural banding at centerline, and mechanical properties through thickness for different ultrafast cooling conditions and rolling temperatures. One set of steels (UC1 and UC2) were ultrafast-cooled (UFC) at 40 K/s after finish rolling at 1223 K and 1193 K (950 °C and 910 °C), respectively, while the second set (LC) was cooled by laminar cooling at 17 K/s after finish rolling at 1238 K (965 °C). UFC produced microstructural variation through thickness; highly dislocated lath-type bainitic ferrite was formed near the surface, whereas the primary microstructure was acicular ferrite and irregular polygonal ferrite in the interior of UC1 and UC2 steels, respectively. However, UFC has the advantage of suppression of microstructural banding in centerline segregation regions. The ferrite grain size in both UFC-cooled steels was refined to ~5 μm, increasing strength and toughness. The optimum combination of properties was obtained in UC2 steel with appropriate low finish rolling temperature, being attributed to the distinct microstructure resulting from work-hardened austenite before UFC.

  3. Influence of cooling rate on the development of multiple generations of {gamma}' precipitates in a commercial nickel base superalloy

    SciTech Connect

    Singh, A.R.P.; Nag, S.; Hwang, J.Y.; Viswanathan, G.B.; Tiley, J.; Srinivasan, R.; Fraser, H.L.; Banerjee, R.

    2011-09-15

    The compositional and microstructural evolution of different generations of {gamma}' precipitates during the continuous cooling of a commercial nickel base superalloy, Rene88DT, has been characterized by three dimensional atom probe tomography coupled with energy-filtered transmission electron microscopy studies. After solutionizing in the single {gamma} phase field, continuous cooling at a very high rate results in a monomodal size distribution of {gamma}' precipitates with a high nucleation density and non-equilibrium compositions. In contrast, a relatively slower cooling rate ({approx} 24 deg. C/min) results in a multi-modal size distribution of {gamma}' precipitates with the larger first generation primary precipitates exhibiting close to equilibrium composition, along with the smaller scale secondary {gamma}' precipitates, exhibiting non-equilibrium composition (excess of Co and Cr, depleted in Al and Ti). The composition of the {gamma} matrix near these precipitates also exhibits similar trends with the composition being closer to equilibrium near the primary precipitates as compared to the secondary precipitates. - Highlights: {yields} Effect of cooling rate on the precipitation of {gamma}' particles in commercial nickel base superalloy. {yields} Couples EFTEM and 3DAP studies to determine the composition and morphology of {gamma}' precipitates. {yields} Determination of near and far field compositional variations within the gamma matrix leading to subsequent precipitation.

  4. Metallographic screening of grain boundary engineered type 304 austenitic stainless steel

    SciTech Connect

    Hanning, F. Engelberg, D.L.

    2014-08-15

    An electrochemical etching method for the identification of grain boundary engineered type 304 austenitic stainless steel microstructures is described. The method can be applied for rapid microstructure screening to complement electron backscatter diffraction analysis. A threshold parameter to identify grain boundary engineered microstructure is proposed, and the application of metallographic etching for characterising the degree of grain boundary engineering discussed. - Highlights: • As-received (annealed) and grain boundary engineered microstructures were compared. • Electro-chemical polarisation in nitric acid solutions was carried out. • A metallographic screening method has been developed. • The screening method complements EBSD analysis for microstructure identification.

  5. Effects of carbon percentage, Stelmor cooling rate and laying head temperature on tensile strength gain in low carbon steels

    NASA Astrophysics Data System (ADS)

    Gade, Surya Prakash

    Low carbon steel wire rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subjected to excessively high work hardening rates during wire drawing process resulting in a variation in wire tensile strength. This research analyzes the effects of carbon percentage, StelmorRTM cooling rate and laying head temperature on the tensile strength gain in wire drawn low carbon steels using design of experiments. The probable reasons for variations in tensile strength gain are analyzed by observing the microstructural changes during experiments. Microstructural analysis was done extensively using optical microscope and Transmission Electron Microscope (TEM) and it was found that the tensile strength gain variation is mainly caused by the increase in the dislocation density in wire rod and wire due to high cooling rate and high laying head temperature, within the range considered. This research concludes that a low carbon wire rod can be produced with minimum tensile strength gain, lower dislocation density and finer ferrite grain size by maintaining a low cooling rate in the StelmorRTM cooling zone and low laying head temperature, which is the temperature at which the wire rod coils are laid on the Stelmor RTM deck. It is also concluded from the results of the present study that: (1) The lowest tensile strength gain is for NS 1006T-3 (0.07 wt.% Carbon) with low cooling rate of 14°F/s and low laying head temperature of 1500°F. (2) The highest tensile strength gain is for NS 1006T-3 with high cooling rate of 26°F/s and high laying head temperature of 1650°F. (3) The effect of StelmorRTM cooling rate and laying head temperature and their interaction are found to be the significant factors causing the variation in wire tensile strength gain. The StelmorRTM cooling rate has the most significant effect on tensile strength gain among the three factors. (4) The effect of carbon percentage on wire tensile strength

  6. Projected Life of the SLAC Linac Braze Joints: Braze integrity and corrosion of cooling water hardware on accelerator sections

    SciTech Connect

    Glesener, W.F.; Garwin, E.L.; /SLAC

    2006-07-17

    The objective of this study was to ascertain the condition of braze joints and cooling water hardware from an accelerator section after prolonged use. Metallographic analysis was used to examine critical sites on an accelerator section that had been in use for more than 30 years. The end flange assembly showed no internal operational damage or external environmental effects. The cavity cylinder stack showed no internal operational damage however the internal surface was highly oxidized. The internal surface of the cooling water tubing was uniformly corroding at a rate of about 1 mil per year and showed no evidence of pitting. Tee fitting internal surfaces are corroding at non-uniform rates due to general corrosion and pitting. Remaining service life of the cooling water jacket is estimated to be about 20 years or year 2027. At this time, water supply pressure will exceed allowable fitting pressure due to corrosion of tubing walls.

  7. The effect of cooling rate on precipitate morphology in Alloy X-750

    SciTech Connect

    Burke, M.G.; Mager, T.R.; Wilson, I.L.W.

    1992-12-31

    Alloy X-750 bar stock was subjected to the following thermal treatment: 1 h at 1093{degrees}C + 24 h at 718{degrees}C. The effect of water-quenching vs. air-cooling from the solution treatment temperature on the subsequent grain boundary precipitation in the near-surface regions was examined and compared to the bulk microstructures using transmission electron microscopy. It was found that water-quenching produced a deformed austenitic structure which promoted cellular M{sub 23}C{sub 6} precipitation upon subsequent aging. Air-cooling resulted in the formation of very fine discrete M{sub 23}C{sub 6} at grain boundaries which continued to grow during additional aging. Both water-quenched and air-cooled materials passed the orthophosphoric acid etch SCC qualification test.

  8. Effect of heating and cooling rate on the kinetics of allotropic phase changes in uranium: A differential scanning calorimetry study

    NASA Astrophysics Data System (ADS)

    Rai, Arun Kumar; Raju, S.; Jeyaganesh, B.; Mohandas, E.; Sudha, R.; Ganesan, V.

    2009-01-01

    The kinetic aspects of allotropic phase changes in uranium are studied as a function of heating/cooling rate in the range 10 0-10 2 K min -1 by isochronal differential scanning calorimetry. The transformation arrest temperatures revealed a remarkable degree of sensitivity to variations of heating and cooling rate, and this is especially more so for the transformation finish ( Tf) temperatures. The results obtained for the α → β and β → γ transformations during heating confirm to the standard Kolmogorov-Johnson-Mehl-Avrami (KJMA) model for a nucleation and growth mediated process. The apparent activation energy Qeff for the overall transformation showed a mild increase with increasing heating rate. In fact, the heating rate normalised Arrhenius rate constant, k/β reveals a smooth power law decay with increasing heating rate (β). For the α → β phase change, the observed DSC peak profile for slower heating rates contained a distinct shoulder like feature, which however is absent in the corresponding profiles found for higher heating rates. The kinetics of γ → β phase change on the other hand, is best described by the two-parameter Koistinen-Marburger empirical relation for the martensitic transformation.

  9. Results of metallographical diagnostic examination of Navy half-watt thermoelectric converters degraded by accelerated tests

    NASA Technical Reports Server (NTRS)

    Rosell, F. E., Jr.; Rouklove, P. G.

    1977-01-01

    To verify the 15-year reliability of the Navy half-watt radioisotope thermoelectric generator (RTG), bismuth-telluride thermoelectric converters were submitted to testing at high temperatures which accelerated the degradation and caused failure of the converters. Metallographic diagnostic examination of failed units verified failure mechanisms. Results of diagnostic examinations are presented.

  10. On morphologies, microsegregation, and mechanical behavior of directionally solidified cobalt-base superalloy at medium cooling rate

    NASA Astrophysics Data System (ADS)

    Chu, Shuangjie; Li, Jianguo; Liu, Zhongyuan; Shi, Zhengxing; Fu, Hengzhi

    1994-03-01

    A newly developed experimental setup that can provide a temperature gradient of 1300 K/cm has been used in the research of the morphologies, microsegregation, and mechanical behavior of directionally solidified cobalt-base superalloy (known as K10 in PR China) at medium cooling rates from 38 to 60 K/s. Experimental results show that the primary and secondary dendrite spacings of K10 become less than one-fifth and one-eighth, respectively, of those obtainable with a conventional 100 K/cm temperature gradient and a cooling rate below 1 K/s: the carbides are directionally arrayed and the carbides’ morphology changes from islands of general cast state into worms; microsegregation is almost completely eliminated; the mechanical properties, as can be expected, are greatly superior to those obtainable with 100 K/cm temperature gradient; at 1073 K, creep-rupture strength increases from 167 to 196 MPa; endurance life is raised from 10 to 30 hours; the reduction in area increases from 12 to 52 pct; and the specific elongation increases from 17 to 46 pct. And with the increase of cooling rate, there are always corresponding improvements of mechanical properties of K10. Otherwise, the fractography of superfine columnar structure samples is high-toughness transgranular fracture, with cracks originating at the edge of carbides.

  11. Effects of post-reflow cooling rate and thermal aging on growth behavior of interfacial intermetallic compound between SAC305 solder and Cu substrate

    NASA Astrophysics Data System (ADS)

    Hu, Xiaowu; Xu, Tao; Jiang, Xiongxin; Li, Yulong; Liu, Yi; Min, Zhixian

    2016-04-01

    The interfacial reactions between Cu and Sn3Ag0.5Cu (SAC305) solder reflowed under various cooling rates were investigated. It is found that the cooling rate is an important parameter in solder reflow process because it influences not only microstructure of solder alloy but also the morphology and growth of intermetallic compounds (IMCs) formed between solder and Cu substrate. The experimental results indicate that only scallop-like Cu6Sn5 IMC layer is observed between solder and Cu substrate in case of water cooling and air cooling, while bilayer composed of scallop-like Cu6Sn5 and thin layer-like Cu3Sn is detected under furnace cooling due to sufficient reaction time to form Cu3Sn between Cu6Sn5 IMC and Cu substrate which resulted from slow cooling rate. Samples with different reflow cooling rates were further thermal-aged at 423 K. And it is found that the thickness of IMC increases linearly with square root of aging time. The growth constants of interfacial IMC layer during aging were obtained and compared for different cooling rates, indicating that the IMC layer thickness increased faster in samples under low cooling rate than in the high cooling rate under the same aging condition. The long prismatic grains were formed on the existing interfacial Cu6Sn5 grains to extrude deeply into solder matrix with lower cooling rate and long-term aging, and the Cu6Sn5 grains coarsened linearly with cubic root of aging time.

  12. Influence of Both Cooling Rate and TeO2 Addition on the Properties of YBCO Superconductor

    NASA Astrophysics Data System (ADS)

    Ahmed, Yasser Momtaz Zaki; Hassan, Mervat Said; Abd-Elatif, Hassan

    2016-08-01

    Composite of superconducting system YBCO-TeO2 was synthesized utilizing solid-state reaction technique. Different weight percentages of TeO2 were mixed with a basic mixture [YBCO] for the synthesis of [YBa2Cu3O7-y ]1-x (TeO2) x composites. These mixtures were sintered at 1213 K (940 °C) for 24 hours and the samples cooled down by two different ways. The first way carried out via slowly cooling in furnace with the rate of 274 K/min to 275 K/min (1 °C/min to 2 °C/min) and the second one is quenching in oxygen gas. The XRD analysis showed that YBCO orthorhombic phase is the major phase appeared in all samples with different TeO2 content regardless of the cooling way. Additionally, minor unknown secondary phases appeared and enlarged with increasing TeO2 addition. Although quenched samples showed a phase difference between the sample's outer surface (orthorhombic) and its interior (tetragonal), the slowly cooled one did not clearly show such distinction. Moreover, doping YBCO with TeO2 leads to increase in the sample bulk density and reduction in their degradation degree in the wet atmosphere.

  13. Quantitative metallographic method for determining delta ferrite content in austenitic stainless steels. Final report

    SciTech Connect

    Pressly, G.A.

    1986-01-01

    Delta ferrite is a magnetic form of iron and has a body centered cubic crystal structure. It is often present as a nonequilibrium phase in austenitic stainless steel welds, castings, and wrought materials. The ferrite content of austenitic stainless steel can directly affect its properties, especially weldability and formability. Therefore, it is highly desirable to be able to predict and/or measure the ferrite content accurately. Current magnetic ferrite measuring methods are not applicable when test materials are geometrically small (less than 2.54 mm thick and 6.35 mm wide). Therefore, a standard metallographic test method STM 00107-A was established to determine delta ferrite content in small weldments and base metals of austenitic stainless steel. This standard test method (STM 00107-A) was then performed on several exemplary metallographic specimens to illustrate its capabilities and applications. The results from the exemplary tests were compared and contrasted to metallographic manual point count measurements, Ferritescope measurements, and predicted values calculated from chemical analyses. By utilizing the manual metallographic point count data, an accuracy of +-16% and a precision of +-0.77% were determined for the standard test method. The comparison of Ferritescope data to standard test method revealed that the results obtained by the two methods are close at low (0 to 3%) ferrite contents and Ferritscope results are substantially greater at higher (6 to 10%) ferrite contents. The standard test method data compiled from the exemplary weld specimens was noted to be very similar to the predicted values calculated from chemical analyses. It was also shown that because the standard test method utilizes optics the morphology of the delta ferrite particles can be determined. This type of determination is possible only with metallographic methods.

  14. Cooling rate dependence of structural order in Al90Sm10 metallic glass

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Zhang, Yue; Zhang, Feng; Ye, Zhuo; Ding, Zejun; Wang, Cai-Zhuang; Ho, Kai-Ming

    2016-07-01

    The atomic structure of Al90Sm10 metallic glass is studied using molecular dynamics simulations. By performing a long sub-Tg annealing, we developed a glass model closer to the experiments than the models prepared by continuous cooling. Using the cluster alignment method, we found that "3661" cluster is the dominating short-range order in the glass samples. The connection and arrangement of "3661" clusters, which define the medium-range order in the system, are enhanced significantly in the sub-Tg annealed sample as compared with the fast cooled glass samples. Unlike some strong binary glass formers such as Cu64.5Zr35.5, the clusters representing the short-range order do not form an interconnected interpenetrating network in Al90Sm10, which has only marginal glass formability.

  15. Development of an intelligent system for cooling rate and fill control in GMAW. [Gas Metal Arc Welding (GMAW)

    SciTech Connect

    Einerson, C.J.; Smartt, H.B.; Johnson, J.A.; Taylor, P.L. ); Moore, K.L. )

    1992-01-01

    A control strategy for gas metal arc welding (GMAW) is developed in which the welding system detects certain existing conditions and adjusts the process in accordance to pre-specified rules. This strategy is used to control the reinforcement and weld bead centerline cooling rate during welding. Relationships between heat and mass transfer rates to the base metal and the required electrode speed and welding speed for specific open circuit voltages are taught to a artificial neural network. Control rules are programmed into a fuzzy logic system. TRADITOINAL CONTROL OF THE GMAW PROCESS is based on the use of explicit welding procedures detailing allowable parameter ranges on a pass by pass basis for a given weld. The present work is an exploration of a completely different approach to welding control. In this work the objectives are to produce welds having desired weld bead reinforcements while maintaining the weld bead centerline cooling rate at preselected values. The need for this specific control is related to fabrication requirements for specific types of pressure vessels. The control strategy involves measuring weld joint transverse cross-sectional area ahead of the welding torch and the weld bead centerline cooling rate behind the weld pool, both by means of video (2), calculating the required process parameters necessary to obtain the needed heat and mass transfer rates (in appropriate dimensions) by means of an artificial neural network, and controlling the heat transfer rate by means of a fuzzy logic controller (3). The result is a welding machine that senses the welding conditions and responds to those conditions on the basis of logical rules, as opposed to producing a weld based on a specific procedure.

  16. Development of a Reliable, Low-cost, Controlled Cooling Rate Instrument for the Cryopreservation of Hematopoietic Stem Cells

    PubMed Central

    Shu, Zhiquan; Kang, Xianjiang; Chen, Hsiuhung; Zhou, Xiaoming; Purtteman, Jester; Yadock, David; Heimfeld, Shelly; Gao, Dayong

    2011-01-01

    An optimal cooling rate is one of the critical factors influencing the survival of cells during cryopreservation. In this paper we describe a novel device, named the box-in-box, which was developed for optimal cryopreservation of human hematopoietic stem cells (HSC). This work presents the design of the device, a mathematical formulation describing the expected temperature histories of samples during the freezing process, along with actual experimental results of thermal profile tests. In experiments, when the box-in-box device was transferred from room temperature to a −80 °C freezer, a cooling rate of −1~−3.5 °C/min, which has been widely used for the cryopreservation of HSC, was achieved. In order to further evaluate this device, HSC cryopreservation was compared between the box-in-box device and a commercially available controlled rate freezer (CryoMed). The experimental data, including total cell population and CD34+ hematopoietic progenitor cell recovery rates, viability, and cell culture colony assays, showed that box-in-box worked as well as CryoMed instrument. There was no significant difference in either survival rate or the culture/colony outcome between the two devices. In conclusion, the box-in-box device can work as a cheap, durable, reliable and maintenance-free instrument for the cryopreservation of HSC. This concept of a box-in-box may also be adapted to other cooling rates to support cryopreservation in a wide variety of tissues and cells. PMID:19929459

  17. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    NASA Astrophysics Data System (ADS)

    Tilocca, Antonio

    2013-09-01

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ˜103 atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application

  18. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    SciTech Connect

    Tilocca, Antonio

    2013-09-21

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10{sup 3} atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their

  19. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics.

    PubMed

    Tilocca, Antonio

    2013-09-21

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ~10(3) atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application

  20. Cooling rate and ice-crystal measurement in biological specimens plunged into liquid ethane, propane, and Freon 22.

    PubMed

    Ryan, K P; Bald, W B; Neumann, K; Simonsberger, P; Purse, D H; Nicholson, D N

    1990-06-01

    Specimens sandwiched between copper planchettes were plunged up to a depth of 430 mm into coolants used for cryofixation. Hydrated gelatin containing a miniature thermocouple was used to mimic the behaviour of tissue during freezing. Gelatin and red blood cells were used for ice-crystal analysis. Ethane produced the fastest cooling rates and the smallest ice-crystal profiles, and Freon 22 produced the slowest cooling rates and the largest crystal profiles. Smaller crystal profiles were often seen in the centre of the specimens than in subsurface zones. The results show that ethane, rather than propane, should be used for freezing metal-sandwiched freeze-fracture specimens by the plunging method, and probably also in the jet-cooling method. They further suggest that good cryofixation could occur at the centre of thin specimens rather than only at their surfaces. Comparison between theoretical and experimental ice-crystal sizes was satisfactory, indicating that where the experimental parameters can be defined then realistic predictions can be made regarding cryofixation results.

  1. Metallographic analysis of irradiated RERTR-3 fuel test specimens.

    SciTech Connect

    Meyer, M. K.; Hofman, G. L.; Strain, R. V.; Clark, C. R.; Stuart, J. R.

    2000-11-08

    The RERTR-3 irradiation test was designed to investigate the irradiation behavior of aluminum matrix U-MO alloy dispersion fuels under high-temperature, high-fission-rate conditions. Initial postirradiation examination of RERTR-3 fuel specimens has concentrated on binary U-MO atomized fuels. The rate of matrix aluminum depletion was found to be higher than predictions based on low temperature irradiation data. Wavelength Dispersive X-ray Spectroscopy (WDS) indicates that aluminum is present in the interior of the fuel particles. WDS data is supported by a mass and volume balance calculation performed on the basis of image analysis results. The depletion of matrix aluminum seems to have no detrimental effects on fuel performance under the conditions tested to date.

  2. Species variation in osmotic, cryoprotectant, and cooling rate tolerance in poultry, eagle, and Peregrine Falcon spermatozoa

    USGS Publications Warehouse

    Blanco, J.M.; Gee, G.; Wildt, D.E.; Donoghue, A.M.

    2000-01-01

    Potential factors influencing spermatozoa survival to cryopreservation and thawing were analyzed across a range of the following avian species: domestic chicken (Gallus domesticus), domestic turkey (Meleagris gallopavo), golden eagle (Aquila chrysaetos), Bonelli's eagle (Hieraaetus fasciatus), imperial eagle (Aquila adalberti), and peregrine falcon (Falco peregrinus). Studies focused on spermatozoa tolerance to the following: 1) osmotic stress, 2) different extracellular concentrations of the cryoprotectant dimethylacetamide (DMA), 3) equilibration times of 1 versus 4 h, 4) equilibration temperature of 4 versus 21 degrees C, and 5) rapid versus slow cooling before cryopreservation and standard thawing. Sperm viability was assessed with the live/dead stain (SYBR14/ propidium iodine). Sperm viability at osmolalities >/=800 mOsm was higher (P: /=2.06 M), experienced decreased (P: < 0.05) spermatozoa survival in all species, except the golden eagle and peregrine falcon. Number of surviving spermatozoa diminished progressively with increasing DMA concentrations in all species. Increased equilibration temperature (from 4 to 21 degrees C) markedly reduced (P: < 0.05) spermatozoa survival in all species except the Bonelli's eagle and turkey. Rapid cooling was detrimental (P: < 0.05) to spermatozoa from all species except the imperial eagle and the chicken. These results demonstrate that avian spermatozoa differ remarkably in response to osmotic changes, DMA concentrations, equilibration time, temperature, and survival after fast or slow freezing. These differences emphasize the need for species-specific studies in the development and enhancement of assisted breeding for poultry and endangered species.

  3. Constraining age and rate of deformation in the northern Bolivian Andes from cross sections, cooling ages, and thermokinematic modeling

    NASA Astrophysics Data System (ADS)

    McQuarrie, N.; Ehlers, T. A.; Rak, A. J.

    2015-12-01

    A critical component in assessing the viability of proposed plate tectonic or geodynamic processes in regions of convergence is the expected or predicted age and rate of deformation in the overriding plate. Commonly, age of deformation is inferred through geochronology of foreland basin and wedge-top sedimentary rocks and bedrock thermochronometer cooling signals. In Bolivia the original pulse of deformation of the fold-thrust belt is argue to be as young as 38-25 Ma based on the age of synorogenic strata or as old as 65-45 Ma due to proposed foreland basin rocks deposited in the Bolivian Altiplano. The large discrepancies in proposed age, rate and magnitude of deformation through the Bolivian Andes limit our ability to relate age and rate of shortening to internal geodynamic or external plate tectonic processes. We evaluate permissible ranges in age of initiation and rate of deformation through a forward kinematic model of the northern Bolivian fold-thrust belt. Each step of deformation accounts for isostatic loading from thrust faults and subsequent erosional of structural highs. The kinematic model predicts an evolution of flexural basins into which synorogenic sediments are deposited allowing us to fully integrate age of exhumation and deposition to age and magnitude of deformation. By assigning an age to each deformation step, we create a range of velocity vectors that are input into the thermokinematic model Pecube, which predicts thermochronometer cooling histories based on kinematics, topography, thermal parameters and shortening rates. We match the pattern of predicted ages with the across strike pattern of measured zircon fission track, apatite fission track and apatite (U-Th)/ He cooling ages. The sensitivity of modeled thermochronologic data to the age at which deformation initiates indicate that northern Bolivian EC started deforming at 50 Ma and may have begun as early as 55 Ma. The acceptable velocity envelope for the modeled section permits either a

  4. Effect of the cooling rate in the crystallization of powdered high-speed steels on the formation of their primary structure

    SciTech Connect

    Kalinushkin, E.P.; Arshava, E.V.; Yakushev, O.S.

    1988-03-01

    The structure formation during solidification of steels R6M5-MP and R6M5F3-MP in a range of cooling rates was studied. Cooling rates were evaluated according to the dendrite parameter. Scanning electron microscopy was used predominantly and the image was formed mainly from the detection of reflected electrons. The structure changed in sequence and an increase of the cooling rate led to stabilization of the front peritectic austenite growth. The eutectic consisted of colonies with predominantly rodlike morphology and crystallization was accompanied by the formation of a fine conglomerate of phases.

  5. Production of bovine cloned embryos with donor cells frozen at a slow cooling rate in a conventional freezer (20 C)

    USGS Publications Warehouse

    Chacon, L.; Gomez, M.C.; Jenkins, J.A.; Leibo, S.P.; Wirtu, G.; Dresser, B.L.; Pope, C.E.

    2009-01-01

    Summary Usually, fibroblasts are frozen in dimethyl sulphoxide (DMSO, 10% v/v) at a cooling rate of 1 C/min in a low-temperature (80 C) freezer (LTF) before storage in liquid nitrogen (LN2); however, a LTF is not always available. The purpose of the present study was to evaluate apoptosis and viability of bovine fibroblasts frozen in a LTF or conventional freezer (CF; 20 C) and their subsequent ability for development to blastocyst stage after fusion with enucleated bovine oocytes. Percentages of live cells frozen in LTF (49.5%) and CF (50.6%) were similar, but significantly less than non-frozen control (88%). In both CF and LTF, percentages of live apoptotic cells exposed to LN2 after freezing were lower (4% and 5%, respectively) as compared with unexposed cells (10% and 18%, respectively). Cells frozen in a CF had fewer cell doublings/24 h (0.45) and required more days (9.1) to reach 100% confluence at the first passage (P) after thawing and plating as compared with cells frozen in a LTF (0.96 and 4.0 days, respectively). Hypoploidy at P12 was higher than at P4 in cells frozen in either a CF (37.5% vs. 19.2%) or in a LTF (30.0% vs. 15.4%). A second-generation cryo-solution reduced the incidence of necrosis (29.4%) at 0 h after thawing as compared with that of a first generation cryo-solution (DMEM + DMSO, 60.2%). The percentage of apoptosis in live cells was affected by cooling rate (CF = 1.9% vs. LFT = 0.7%). Development of bovine cloned embryos to the blastocyst stage was not affected by cooling rate or freezer type. ?? 2009 Cambridge University Press.

  6. Species variation in osmotic, cryoprotectant, and cooling rate tolerance in poultry, eagle, and peregrine falcon spermatozoa.

    PubMed

    Blanco, J M; Gee, G; Wildt, D E; Donoghue, A M

    2000-10-01

    Potential factors influencing spermatozoa survival to cryopreservation and thawing were analyzed across a range of the following avian species: domestic chicken (Gallus domesticus), domestic turkey (Meleagris gallopavo), golden eagle (Aquila chrysaetos), Bonelli's eagle (Hieraaetus fasciatus), imperial eagle (Aquila adalberti), and peregrine falcon (Falco peregrinus). Studies focused on spermatozoa tolerance to the following: 1) osmotic stress, 2) different extracellular concentrations of the cryoprotectant dimethylacetamide (DMA), 3) equilibration times of 1 versus 4 h, 4) equilibration temperature of 4 versus 21 degrees C, and 5) rapid versus slow cooling before cryopreservation and standard thawing. Sperm viability was assessed with the live/dead stain (SYBR-14/propidium iodine). Sperm viability at osmolalities >/=800 mOsm was higher (P: < 0.05) in raptor than poultry semen. Return to isotonicity after exposure to hypertonicity (3000 mOsm) decreased (P: < 0.05) number of viable spermatozoa in chicken, turkey, and golden and Bonelli's eagle spermatozoa but not in imperial eagle or peregrine falcon spermatozoa. Differences were found in spermatozoa resistance to hypotonic conditions, with eagle species demonstrating the most tolerance. Semen, equilibrated for 1 h (4 degrees C) in diluent containing DMA (> or =2.06 M), experienced decreased (P: < 0. 05) spermatozoa survival in all species, except the golden eagle and peregrine falcon. Number of surviving spermatozoa diminished progressively with increasing DMA concentrations in all species. Increased equilibration temperature (from 4 to 21 degrees C) markedly reduced (P: < 0.05) spermatozoa survival in all species except the Bonelli's eagle and turkey. Rapid cooling was detrimental (P: < 0.05) to spermatozoa from all species except the imperial eagle and the chicken. These results demonstrate that avian spermatozoa differ remarkably in response to osmotic changes, DMA concentrations, equilibration time, temperature

  7. Liquidus temperatures of komatiites and the effect of cooling rate on element partitioning between olivine and komatiitic melt

    NASA Astrophysics Data System (ADS)

    Sossi, Paolo A.; O'Neill, Hugh St. C.

    2016-05-01

    Archean komatiites are the hottest magmas preserved on Earth and are thus unique probes of its thermal evolution. Estimating their eruption temperatures remains problematic, however, because the uppermost (A1, A2) zones of komatiite flows contain randomly oriented spinifex-textured olivines, indicative of rapid cooling and growth. Fe-Mg partitioning between olivine and assumed komatiitic liquid typically shows departures from equilibrium, extending towards higher K_{{D}}^{{{{Fe}}^{2 + } - {{Mg}}}}. If these higher values are a disequilibrium effect, using them to calculate parental magma composition would lead to errors in estimated liquidus temperatures. In order to investigate this possibility, we have performed experiments on two komatiite compositions, the classic Barberton Aluminium Undepleted Komatiite (AUK) sample 49J (32.2 % MgO) and Munro AUK sample 422/95 (23 % MgO). Isothermal experiments to constrain phase equilibria on 49J at atmospheric pressure, between 1360 and 1600 °C at 1.7 log units below and 1.1 above the fayalite-magnetite-quartz (FMQ) buffer reveal a liquidus temperature ( T liq) of 1616 °C, 40 °C lower than a previous estimate. The K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} ranges between 0.320 and 0.295 at FMQ - 1.7, with a slight negative dependence on temperature. To replicate the conditions that prevailed during the quenching of komatiites in their upper chill zones, experiments with a constant cooling rate at FMQ - 1.7 were performed on 422/95 ( T liq = 1450 °C) at 0.5, 1.5, 2.5, 6.5 and 16 °C/min. Olivine morphology changes from euhedral to tabular at low cooling rates, hopper at intermediate, and skeletal and chain structures at high rates. Concurrently, the K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} increases monotonically from an equilibrium value of 0.305 to 0.376 at 16 °C/min, reflecting the inability of unwanted cations to diffuse away from the growing olivine. The high K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} between olivine and komatiitic liquid caused by

  8. Assessing inflow rates in atomic cooling haloes: implications for direct collapse black holes

    NASA Astrophysics Data System (ADS)

    Latif, M. A.; Volonteri, M.

    2015-09-01

    Supermassive black holes are not only common in the present-day galaxies, but billion solar masses black holes also powered z ≥ 6 quasars. One efficient way to form such black holes is the collapse of a massive primordial gas cloud into a so-called direct collapse black hole. The main requirement for this scenario is the presence of large accretion rates of ≥ 0.1 M⊙ yr- 1 to form a supermassive star. It is not yet clear how and under what conditions such accretion rates can be obtained. The prime aim of this work is to determine the mass accretion rates under non-isothermal collapse conditions. We perform high-resolution cosmological simulations for three primordial haloes of a few times 107 M⊙ illuminated by an external UV flux, J21 = 100-1000. We find that a rotationally supported structure of about parsec size is assembled, with an aspect ratio between 0.25 and 1 depending upon the thermodynamical properties. Rotational support, however, does not halt collapse, and mass inflow rates of ˜ 0.1 M⊙ yr- 1 can be obtained in the presence of even a moderate UV background flux of strength J21 ≥ 100. To assess whether such large accretion rates can be maintained over longer time-scales, we employed sink particles, confirming the persistence of accretion rates of ˜ 0.1 M⊙ yr- 1. We propose that complete isothermal collapse and molecular hydrogen suppression may not always be necessary to form supermassive stars, precursors of black hole seeds. Sufficiently high inflow rates can be obtained for UV flux J21 = 500-1000, at least for some cases. This value brings the estimate of the abundance of direct collapse black hole seeds closer to that high-redshift quasars.

  9. Analysis of isothermal and cooling-rate-dependent immersion freezing by a unifying stochastic ice nucleation model

    DOE PAGES

    Alpert, Peter A.; Knopf, Daniel A.

    2016-02-24

    Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature, T, and relative humidity, RH, at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling-rate-dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nucleating particles (INPs) all have the same INP surface area (ISA); however, the validity of this assumption or the impact it may have on analysis and interpretation of the experimentalmore » data is rarely questioned. Descriptions of ice active sites and variability of contact angles have been successfully formulated to describe ice nucleation experimental data in previous research; however, we consider the ability of a stochastic freezing model founded on classical nucleation theory to reproduce previous results and to explain experimental uncertainties and data scatter. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses parameters including the total number of droplets, Ntot, and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA-dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically

  10. Analysis of isothermal and cooling-rate-dependent immersion freezing by a unifying stochastic ice nucleation model

    NASA Astrophysics Data System (ADS)

    Alpert, Peter A.; Knopf, Daniel A.

    2016-02-01

    Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature, T, and relative humidity, RH, at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling-rate-dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nucleating particles (INPs) all have the same INP surface area (ISA); however, the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. Descriptions of ice active sites and variability of contact angles have been successfully formulated to describe ice nucleation experimental data in previous research; however, we consider the ability of a stochastic freezing model founded on classical nucleation theory to reproduce previous results and to explain experimental uncertainties and data scatter. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses parameters including the total number of droplets, Ntot, and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA-dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets

  11. Experimental constraints on heating and cooling rates of refractory inclusions in the early solar system

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.; DRAKE; HILDEBRAND; JONES; LEWIS; TREIMAN; WARK

    1987-01-01

    The refractory inclusions in carbonaceous chondrites were the subject of considerable interest since their discovery. These inclusions contain minerals that are predicted to be some of the earliest condensates from the solar nebula, and contain a plethora of isotopic anomalies of unknown origin. Of particular interest are those coarse-grained inclusions that contain refractory metal particles (Fe, Ni, Pt, Ru, Os Ir). Experimental studies of these inclusions in terrestrial laboratories are, however, complicated because the dense particles tend to settle out of a molten or partially molten silicate material. Heating experiments in the Space Station technology and microgravity in order to observe the effects of metal nuggets (which may act as heterogeneous nucleation sites) on nucleation rates in silicate systems and to measure simultaneously the relative volatilization rate of siderophile and lithophile species. Neither experiment is possible in the terrestrial environment.

  12. Constraining cooling rates of UHP metamorphic rocks with closure temperature geospeedometry: a case study from the Dabie orogen

    NASA Astrophysics Data System (ADS)

    Lloyd, M. K.; Shimizu, N.; Wang, Z.; Zheng, Y.

    2011-12-01

    UHP metamorphic rocks can reach peak temperatures and pressures >800°C and >3GPa, and provide unique opportunities for studying geochemical processes in subduction zones. How and how fast they were exhumed are, however, still outstanding questions. Here we report SIMS-based Zr concentrations in rutiles from an eclogite sample from Huangzhen in the South Dabie low-T/UHP zone, east-central China, and present a closure temperature-based approach to constrain the cooling/exhumation rate of UHP rocks. Li et al. (2004) put peak metamorphism at a time prior to 236.1 ± 4.2 Ma., but estimates for peak temperatures and pressures in South Dabie vary wildly depending on the rock suite. The fine-grained eclogites in the Dabie orogen were estimated to have reached conditions of 641-839 °C and 2.00-3.54 GPa (Shi and Wang, 2006) based on Fe-Mg partition thermometry and metamorphic phase equilibria. These samples were reported to contain quartz, zircon, and rutile phases that reached thermodynamic equilibrium with each other. In this study, Zr concentrations of rutiles were obtained using the Cameca IMS 1280 ion microprobe at Northeast National Ion Microprobe Facility, by converting secondary ion intensity ratios, 90Zr/46Ti, to concentrations using rutile standards described by Luvizotto et al. (2009), with analytical uncertainties of 5.1%. Temperatures were then calculated using the method of Ferry and Watson (2007). It was found that Zr concentrations range from 38.6(2.4) to 134.6(4.5) ppm, resulting in a temperature range of 504(24) to 583(27)°C for 72 grains with size spanning from 62 to 440 microns cross in long axis. Minor rim-ward decrease of Zr content was observed with no appreciable temperature decrease. Assuming that the rutiles grew at one stage during the peak metamorphism and that their Zr concentrations were independent of pressure, a cooling rate can be estimated for the target sample. By applying the Dodson (1973) formula for closure temperature in conjunction

  13. Assessment of external heat transfer coefficient during oocyte vitrification in liquid and slush nitrogen using numerical simulations to determine cooling rates.

    PubMed

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2012-01-01

    In oocyte vitrification, plunging directly into liquid nitrogen favor film boiling and strong nitrogen vaporization. A survey of literature values of heat transfer coefficients (h) for film boiling of small metal objects with different geometries plunged in liquid nitrogen revealed values between 125 to 1000 W per per square m per K. These h values were used in a numerical simulation of cooling rates of two oocyte vitrification devices (open-pulled straw and Cryotop), plunged in liquid and slush nitrogen conditions. Heat conduction equation with convective boundary condition was considered a linear mathematical problem and was solved using the finite element method applying the variational formulation. COMSOL Multiphysics was used to simulate the cooling process of the systems. Predicted cooling rates for OPS and Cryotop when cooled at -196 degree C (liquid nitrogen) or -207 degree C (average for slush nitrogen) for heat transfer coefficients estimated to be representative of film boiling, indicated lowering the cooling temperature produces only a maximum 10 percent increase in cooling rates; confirming the main benefit of plunging in slush over liquid nitrogen does not arise from their temperature difference. Numerical simulations also demonstrated that a hypothetical four-fold increase in the cooling rate of vitrification devices when plunging in slush nitrogen would be explained by an increase in heat transfer coefficient. This improvement in heat transfer (i.e., high cooling rates) in slush nitrogen is attributed to less or null film boiling when a sample is placed in slush (mixture of liquid and solid nitrogen) because it first melts the solid nitrogen before causing the liquid to boil and form a film.

  14. Growth Behavior of Intermetallic Compounds in Cu/Sn3.0Ag0.5Cu Solder Joints with Different Rates of Cooling

    NASA Astrophysics Data System (ADS)

    Yang, Linmei; Zhang, Z. F.

    2015-01-01

    The growth behavior of intermetallic compounds (IMC) in Cu/Sn3.0Ag0.5Cu solder joints, including the interfacial Cu6Sn5 layer and Ag3Sn, and Cu6Sn5 in the solder, were investigated when different cooling methods—quenched water, cooling in air, and cooling in a furnace after reflow—were used. For the solder joint quenched in water, no obvious Cu6Sn5 or Ag3Sn was detected in the solder, and the thickness of interfacial Cu6Sn5 layer was slightly thinner than that of the joint cooled in air. On the basis of results from scanning electron microscopy and energy-dispersive spectrometry, a mechanism is proposed for growth of IMC in Sn3.0Ag0.5Cu solder during solidification. The rate of cooling has a substantial effect on the morphology and size of Ag3Sn, which evolved into large plate-like shapes when the joint was cooled slowly in a furnace. However, the morphology of Ag3Sn was branch-like or particle-like when the joint was cooled in air. This is attributed to re-growth of Ag3Sn grains via substantial atomic diffusion during the high-temperature stage of furnace cooling.

  15. Some Investigations on Effect of Cooling Rate on Al2O3 Reinforced Al-MMC Prepared by Vacuum Moulding

    NASA Astrophysics Data System (ADS)

    Singh, Rupinder; Sahni, Kanwalpreet

    2016-07-01

    In the present research work effort has been made to study the effect of cooling rate of Al2O3 reinforced; aluminum metal matrix composites (Al-MMC) on hardness of component prepared by vacuum moulding (VM) process. The study started with selection of the component for industrial application. This study also highlights the effect of reinforcement in form of double particle size and triple particle size on hardness of Al-Al2O3 MMC. The input parameters of process are composition of MMC, vacuum moulding silica sand AFS No., vacuum pressure and component volume. The results of study supported by microstructure analysis suggest the geometric model for MMC hardness prepared by VM process.

  16. Effect of cryoprotectants and cooling rates on fertility potential of sperm in the giant freshwater prawn, Macrobrachium rosenbergii (De Man).

    PubMed

    Valentina Claudet, P; Narasimman, Selvakumar; Natesan, Munuswamy

    2016-08-01

    This study evaluates freezing protocol with suitable cryoprotectants and their effects on the fertility potential of sperm in the cryopreserved spermatophores of Macrobrachium rosenbergii. Spermatophores, collected using electroejaculation, were suspended in dimethyl sulfoxide (DMSO), propylene glycol (PG), methanol, glycerol and ethylene glycol (EG) at different concentrations (10, 15 & 20% v/v), prepared in sterile-filtered pond water. Based on the cryoprotectant toxicity assay, DMSO and PG were used individually as well as in combination with three freezing protocols (i.e. -1.5, -3 and -5°C/min and to final temperature of -39°C) and plunged into liquid nitrogen at -196°C. After 90 days of storage (-196°C) thawing was done at 35°C in a water bath for 1min. Results showed that fresh and cryopreserved spermatophores held for 90 days registered sperm viability of 91.4±2.9% and 50.4±1.9% respectively. Further, fertility potential of sperm was assessed based on acrosome reactivity using calcium ionophore (A23187). Observations indicated that cryopreserved sperm registered 28.3±2.2% of acrosome reactivity compared to freshly collected spermatophores (85.3±2.5%). Thus, one-step slow cooling rate of -1.5°C/min between 27°C and -39°C stored in liquid nitrogen at -196°C with DMSO (10%)+PG (10%) seems to be amenable for cryopreservation of spermatophores, compared to other cooling rates.

  17. Effect of cryoprotectants and cooling rates on fertility potential of sperm in the giant freshwater prawn, Macrobrachium rosenbergii (De Man).

    PubMed

    Valentina Claudet, P; Narasimman, Selvakumar; Natesan, Munuswamy

    2016-08-01

    This study evaluates freezing protocol with suitable cryoprotectants and their effects on the fertility potential of sperm in the cryopreserved spermatophores of Macrobrachium rosenbergii. Spermatophores, collected using electroejaculation, were suspended in dimethyl sulfoxide (DMSO), propylene glycol (PG), methanol, glycerol and ethylene glycol (EG) at different concentrations (10, 15 & 20% v/v), prepared in sterile-filtered pond water. Based on the cryoprotectant toxicity assay, DMSO and PG were used individually as well as in combination with three freezing protocols (i.e. -1.5, -3 and -5°C/min and to final temperature of -39°C) and plunged into liquid nitrogen at -196°C. After 90 days of storage (-196°C) thawing was done at 35°C in a water bath for 1min. Results showed that fresh and cryopreserved spermatophores held for 90 days registered sperm viability of 91.4±2.9% and 50.4±1.9% respectively. Further, fertility potential of sperm was assessed based on acrosome reactivity using calcium ionophore (A23187). Observations indicated that cryopreserved sperm registered 28.3±2.2% of acrosome reactivity compared to freshly collected spermatophores (85.3±2.5%). Thus, one-step slow cooling rate of -1.5°C/min between 27°C and -39°C stored in liquid nitrogen at -196°C with DMSO (10%)+PG (10%) seems to be amenable for cryopreservation of spermatophores, compared to other cooling rates. PMID:27318716

  18. Metallographic examination of damaged N reactor spent nuclear fuel element SFEC5,4378

    SciTech Connect

    Marschman, S.C.; Pyecha, T.D.; Abrefah, J.

    1997-08-01

    N-Reactor spent nuclear fuel (SNF) is currently residing underwater in the K Basins at the Hanford site, in Richland, Washington. This report presents results of the metallographic examination of specimens cut from an SNF element (Mark IV-E) with breached cladding. The element had resided in the K-West (KW) Storage Basin for at least 10 years after it was discharged from the N-Reactor. The storage containers in the KW Basin were nominally closed, isolating the SNF elements from the open pool environment. Seven specimens from this Mark IV-E outer fuel element were examined using an optical metallograph. Included were two specimens that had been subjected to a conditioning process recommended by the Independent Technical Assessment Team, two specimens that had been subjected to a conditioning process recommended in the Integrated Process Strategy Report, and three that were in the as-received, as-cut condition. One of the as-received specimens had been cut from the damaged (or breached) end of the element. All other specimens were cut from the undamaged mid-region of the fuel element. The specimens were visually examined to (1) identify uranium hydride inclusions present in the uranium metal fuel, (2) measure the thickness of the oxide layer formed on the uranium edges and assess the apparent integrity and adhesion of the oxide layer, and (3) look for features in the microstructure that might provide an insight into the various corrosion processes that occurred during underwater storage in the KW Basin. These features included, but were not limited to, the integrity of the cladding and the fuel-to-cladding bond, obvious anomalies in the microstructure, excessive pitting or friability of the fuel matrix, and obvious anomalies in the distribution of uranium hydride or uranium carbide inclusions. Also, the observed metallographic features of the conditioned specimens were compared with those of the as-received (unconditioned) specimens. 11 refs., 93 figs., 2 tabs.

  19. Cool Bands: Wing bands decrease rate of heating, but not equilibrium temperature in Anartia fatima.

    PubMed

    Brashears, Jake; Aiello, Annette; Seymoure, Brett M

    2016-02-01

    Butterflies regulate their internal thoracic temperature in order to optimize performance activities (e.g. flight, foraging). Previous research has shown that butterfly wings, particularly the innermost portions, play a role in thermoregulation. We investigated to see whether a lightly colored wing band would alter the thermal properties of the banded peacock butterfly (Anartia fatima) with two within subject experiments in a laboratory setting: (1) band color manipulation in which euthanized individuals were heated to thermal equilibrium with the band unaltered and then again with the wing darkened; (2) wing ablation in which individuals already run through experiment 1 were heated to equilibrium two more times; once with the outer portion of the wing including the band removed and then with the entire wing removed. Individuals were spread so that the dorsal surface of the wing was exposed to illumination from a lamp suspended above. Twelve Anartia fatima males were collected in Panama and were run through experiment one. Four individuals were run through experiment two. We found no effect of darkening the band on the internal thoracic equilibrium temperature, but the darkened band did increase the rate of heating. The wing ablation experiment revealed that wing removal lowered the internal thoracic equilibrium temperature but did not affect the heating rate. Therefore we show that butterfly bands may be important in butterfly thermoregulation and we discuss the importance of the wing band on thermoregulatory abilities in Anartia fatima with respect to the butterfly's natural history. We conclude that the wing band may allow butterflies to reduce heat stress induced by their warm environments.

  20. Cool Bands: Wing bands decrease rate of heating, but not equilibrium temperature in Anartia fatima.

    PubMed

    Brashears, Jake; Aiello, Annette; Seymoure, Brett M

    2016-02-01

    Butterflies regulate their internal thoracic temperature in order to optimize performance activities (e.g. flight, foraging). Previous research has shown that butterfly wings, particularly the innermost portions, play a role in thermoregulation. We investigated to see whether a lightly colored wing band would alter the thermal properties of the banded peacock butterfly (Anartia fatima) with two within subject experiments in a laboratory setting: (1) band color manipulation in which euthanized individuals were heated to thermal equilibrium with the band unaltered and then again with the wing darkened; (2) wing ablation in which individuals already run through experiment 1 were heated to equilibrium two more times; once with the outer portion of the wing including the band removed and then with the entire wing removed. Individuals were spread so that the dorsal surface of the wing was exposed to illumination from a lamp suspended above. Twelve Anartia fatima males were collected in Panama and were run through experiment one. Four individuals were run through experiment two. We found no effect of darkening the band on the internal thoracic equilibrium temperature, but the darkened band did increase the rate of heating. The wing ablation experiment revealed that wing removal lowered the internal thoracic equilibrium temperature but did not affect the heating rate. Therefore we show that butterfly bands may be important in butterfly thermoregulation and we discuss the importance of the wing band on thermoregulatory abilities in Anartia fatima with respect to the butterfly's natural history. We conclude that the wing band may allow butterflies to reduce heat stress induced by their warm environments. PMID:26857983

  1. Effectiveness of eugenol sedation to reduce the metabolic rates of cool and warm water fish at high loading densities

    USGS Publications Warehouse

    Cupp, Aaron R.; Hartleb, Christopher F.; Fredricks, Kim T.; Gaikowski, Mark P.

    2016-01-01

    Effects of eugenol (AQUI-S®20E, 10% active eugenol) sedation on cool water, yellow perch Perca flavescens (Mitchill), and warm water, Nile tilapia Oreochromis niloticus L. fish metabolic rates were assessed. Both species were exposed to 0, 10, 20 and 30 mg L−1 eugenol using static respirometry. In 17°C water and loading densities of 60, 120 and 240 g L−1, yellow perch controls (0 mg L−1 eugenol) had metabolic rates of 329.6–400.0 mg O2 kg−1 h−1, while yellow perch exposed to 20 and 30 mg L−1 eugenol had significantly reduced metabolic rates of 258.4–325.6 and 189.1–271.0 mg O2 kg−1 h−1 respectively. Nile tilapia exposed to 30 mg L−1 eugenol had a significantly reduced metabolic rate (424.5 ± 42.3 mg O2 kg−1 h−1) relative to the 0 mg L−1 eugenol control (546.6 ± 53.5 mg O2 kg−1 h−1) at a loading density of 120 g L−1 in 22°C water. No significant differences in metabolic rates for Nile tilapia were found at 240 or 360 g L−1 loading densities when exposed to eugenol. Results suggest that eugenol sedation may benefit yellow perch welfare at high densities (e.g. live transport) due to a reduction in metabolic rates, while further research is needed to assess the benefits of eugenol sedation on Nile tilapia at high loading densities.

  2. Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

    PubMed

    Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

    2012-05-01

    Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw.

  3. Evaluation of the Variation in Cooling Rate with Depth in the Lower Oceanic Crust at Fast-Spreading Ridges Using a Newly Developed Mg in Plagioclase Geospeedometer

    NASA Astrophysics Data System (ADS)

    Faak, K.; Chakraborty, S.; Coogan, L. A.

    2011-12-01

    The crystallization and cooling of new oceanic crust is regenerating two thirds of the Earth's surface continuously but the processes that occur during the cooling and crystallization of the magma are still poorly understood. Two end-member models have been proposed for lower crustal accretion at intermediate- to fast-spreading ridges (the "gabbro glacier" and "sheeted sill" models). These require different depth distributions of hydrothermal circulation and are likely to result in different variations of cooling rates with depth. Mapping cooling rates of samples of the lower oceanic crust as a function of depth can, therefore, allow us to distinguish between the models and constrain the thermal evolution during the generation of oceanic crust. We have developed a new geospeedometer, based on the exchange of Mg between plagioclase and clinopyroxene, to address this problem. New experiments demonstrate that the partitioning of Mg between clinopyroxene and plagioclase is strongly temperature dependent, changing by a factor of 4 between 1200°C and 900°C, such that during cooling Mg diffuses out of plagioclase into adjacent clinopyroxene grains. A finite difference diffusion model of Mg redistribution during cooling is applied to natural samples from the north wall of the Hess Deep Rift at the East Pacific Rise. 90 concentration profiles (rim - rim) from 45 crystals in 14 samples (from a depth range 0-520m below the sheeted dikes) were measured using an electron microprobe. For obtaining reliable cooling rates, Mg concentration profiles were measured along two crystallographic directions in a grain, and profiles from several crystals in one thin section are modeled. Cooling rate determinations are considered reliable only when results from all of these calculations are consistent. Fresh plagioclase crystals in coarse grained gabbros (mean grain size ~ 1mm) were chosen for the measurement of Mg contents. The shapes of these measured concentration profiles are very

  4. Intracellular ice formation in mouse zygotes and early morulae vs. cooling rate and temperature-experimental vs. theory.

    PubMed

    Jin, Bo; Seki, Shinsuke; Paredes, Estefania; Qiu, Juan; Shi, Yanbin; Zhang, Zhenqiang; Ma, Chao; Jiang, Shuyan; Li, Jiaqi; Yuan, Feng; Wang, Shu; Shao, Xiaoguang; Mazur, Peter

    2016-10-01

    In this study, mature female mice of the ICR strain were induced to superovultate, mated, and collected at either zygote or early morula stages. Embryos suspended in 1 M ethylene glycol in PBS containing 10 mg/L Snomax for 15 min, then transferred in sample holder to Linkam cryostage, cooled to and seeded at 7 °C, and then observed and photographed while being cooled to -70 °C at 0.5-20 °C/min. Intracellular ice formation (IIF) was observed as abrupt ''flashing''. Two types of flashing or IIF were observed in this study. Extracellular freezing occurred at a mean of -7.7 °C. In morulae, about 25% turned dark within ±1 °C of extracellular ice formation (EIF). These we refer to as "high temperature'' flashers. In zygotes, there were no high temperature flashers. All the zygotes flashed at temperatures well below the temperature for EIF. Presumably high temperature flashers were a consequence of membrane damage prior to EIF or damage from EIF. We shall not discuss them further. In the majority of cases, IIF occurred well below -7.7 °C; these we call ''low temperature'' flashers. None flashed with cooling rate (CR) of 0.5 °C/min in either zygotes or morulae. Nearly all flashed with CR of 4 °C/min or higher, but the distribution of temperatures is much broader with morulae than with zygotes. Also, the mean flashing temperature is much higher with morulae (-20.9 °C) than with zygotes (-40.3 °C). We computed the kinetics of water loss with respect to CR and temperature in both mouse zygotes and in morulae based on published estimates of Lp and it is Ea. The resulting dehydration curves combined with knowledge of the embryo nucleation temperature permits an estimate of the likelihood of IIF as a function of CR and subzero temperature. The agreement between these computed probabilities and the observed values are good. PMID:27481511

  5. Investigation on the Effect of Mold Constraints and Cooling Rate on Residual Stress During the Sand-Casting Process of 1086 Steel by Employing a Thermomechanical Model

    NASA Astrophysics Data System (ADS)

    Baghani, Amir; Davami, Parviz; Varahram, Naser; Shabani, Mohsen Ostad

    2014-06-01

    In this study, the effects of mold constraints and cooling rate on residual stress were analyzed during the shaped casting process. For this purpose, an H-shaped sample was designed in which the contraction of its middle portion is highly restricted by the mold during the cooling process. The effects of an increasing cooling rate combined with mold constraints were analyzed by reducing the thickness of the middle portion in the second sample. A three-dimensional coupled temperature-displacement analysis was performed in finite-element code ABAQUS to simulate residual stress distribution, and then numerical results were verified by the hole-drilling strain-gauge method. It was concluded that the mold constraints have a greater effect on the values of residual stress than the cooling rate (thin section) in steel sand casting. Increasing the cooling rate would increase the amount of residual stress, only in the presence of mold constraints. It is also suggested that employing the elastic-plastic stress model for the sand mold will satisfy the experimental results and avoid exaggerated values of residual stress in simulation.

  6. The Influence of Cooling Rate During Crystallization on the Effective Partitioning Coefficient in High-Entropy Alloys from Al-Ti-Co-Ni-Fe System

    NASA Astrophysics Data System (ADS)

    Górecki, Kamil; Bala, Piotr; Cios, Grzegorz; Koziel, Tomasz; Stępień, Milena; Wieczerzak, Krzysztof

    2016-07-01

    An influence of two different cooling rates on the microstructure and dispersion of the components of high-entropy alloy from Al-Ti-Co-Ni-Fe system has been examined. For investigated alloys, the effective partitioning coefficient has been calculated. This factor indicates the degree of segregation of elements and allows for the specification of the differences between dendrites and interdendritic regions. The obtained results allow for the conclusion that the cooling rate substantially affect the growth of dendrites and the volume fraction of interdendritic regions as well as the partitioning of elements in the alloy. Furthermore, the obtained results made it possible to compare the influence of the cooling rate and the chemical composition on the dispersion of the alloying elements.

  7. The Fe2(+)-Mg interdiffusion in orthopyroxene: Constraints from cation ordering and structural data and implications for cooling rates of meteorites

    NASA Technical Reports Server (NTRS)

    Ganguly, J.; Tazzoli, V.

    1993-01-01

    Orthopyroxene crystals in a number of meteorites exhibit compositional zoning of Fe and Mg, which provide important constraint on their cooling rates. However, attempts to model cooling rate of these crystals from Fe-Mg zoning profiles suffer from the lack of any measured or theoretically well constrained Fe-Mg interdiffusion data in OP(x) It has been assumed that Fe-Mg interdiffusion in OP(x) only slightly slower than that in olivine. The purpose of this paper is to (1) calculate the Fe-Mg fractionation, and (2) provide analytical formulation relating cooling rate to the length of the diffusion zone across the interface of the overgrowth of a mineral on itself with application to Mg diffusion profile across OP(x) growth on OP(x) in certain mesosiderites.

  8. Thermophoretically enhanced mass transport rates to solid and transpiration-cooled walls across turbulent (law-of-the-wall) boundary layers

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.; Rosner, Daniel E.

    1985-01-01

    Convective-diffusion mass transfer rate predictions are made for both solid wall and transpiration-cooled 'law-of-the-wall' nonisothermal turbulent boundary layers (TBLs), including the mechanism of thermophoresis, i.e., small particle mass transport 'down a temperature gradient'. The present calculations are confined to low mass-loading situations but span the entire particle size range from vapor molecules to particles near the onset of inertial ('eddy') impaction. It is shown that, when Sc is much greater than 1, thermophoresis greatly increases particle deposition rates to internally cooled solid walls, but only partially offsets the appreciable reduction in deposition rates associated with dust-free gas-transpiration-cooled surfaces. Thus, efficient particle sampling from hot dusty gases can be carried out using transpiration 'shielded' probe surfaces.

  9. Effects of cooling rate, saturation temperature, and agitation on the metastable zone width of DL-malic acid-water system

    NASA Astrophysics Data System (ADS)

    Yuan, Ye; Leng, Yixin; Huang, Chunxiang; Yue, Mingxuan; Tan, Qian

    2015-09-01

    A study of metastable zone width (MSZW) and nucleation parameters for a cooling crystallization of DL-malic acid-water system is described in this paper. Experimental determination of the MSZW was performed using a laser method in order to carry out the estimation of nucleation parameters. Measured MSZWs can be affected by a variety of parameters, such as cooling rate, saturation temperature, agitation rate, and so on. In this work, the MSZWs were found to decrease with an increase of saturation temperature, and levels of agitation, while it increased with an increase of cooling rate. Two classical theoretical approaches, Nyvlt's approach and self-consistent Nyvlt-like approach were used to analyze the experimental data on MSZWs.

  10. Theoretical prediction of the effect of heat transfer parameters on cooling rates of liquid-filled plastic straws used for cryopreservation of spermatozoa.

    PubMed

    Sansinen, M; Santos, M V; Zaritzky, N; Baez, R; Chirife, J

    2010-01-01

    Heat transfer plays a key role in cryopreservation of liquid semen in plastic straws. The effect of several parameters on the cooling rate of a liquid-filled polypropylene straw when plunged into liquid nitrogen was investigated using a theoretical model. The geometry of the straw containing the liquid was assimilated as two concentric finite cylinders of different materials: the fluid and the straw; the unsteady-state heat conduction equation for concentric cylinders was numerically solved. Parameters studied include external (convection) heat transfer coefficient (h), the thermal properties of straw manufacturing material and wall thickness. It was concluded that the single most important parameter affecting the cooling rate of a liquid column contained in a straw is the external heat transfer coefficient in LN2. Consequently, in order to attain maximum cooling rates, conditions have to be designed to obtain the highest possible heat transfer coefficient when the plastic straw is plunged in liquid nitrogen.

  11. Redefining cooling rate in terms of ice front velocity and thermal gradient: first evidence of relevance to freezing injury of lymphocytes.

    PubMed

    Beckmann, J; Körber, C; Rau, G; Hubel, A; Cravalho, E G

    1990-06-01

    A freezing process and the resulting injury or survival of biological cells is commonly characterized in terms of the cooling rate, B. Under certain circumstances, the cooling rate can be expressed as B = G.v, where G denotes the thermal gradient at the ice-liquid interface and v its velocity, respectively. To determine the influence of G and v on the morphology of the ice-liquid interface and on cell survival, a gradient freezing stage was designed. Flat capillaries could be pushed with constant velocity from a warm to a cold heat reservoir. With this setup both parameters, G and v, are independently adjustable and the resulting process of directional solidification can be observed dynamically in a light microscope. Human lymphocytes in phosphate-buffered saline with 10 vol% of dimethyl sulfoxide were used as biological test material. Viability was assessed by a membrane integrity test with fluorescein diacetate and ethidium bromide. All cells were cooled down to a final temperature of -196 degrees C and then rapidly thawed. The results obtained with this technique show that the viability determined after freezing and thawing with a certain cooling rate, B = G.v, may vary considerably depending on the imposed values of the thermal gradient, G, and the ice front velocity, v. In addition, the data seem to suggest that, first, the maximum viability which can be reached is governed by the cooling rate, and, second, this maximum for a given cooling rate could be achieved by establishing small temperature gradients and high interface velocities (about 30 degrees K/cm and 500 microns/sec, respectively, for the range of values of G and v tested). PMID:2379414

  12. Fearsome Flashes: A Study Of The Evolution Of Flaring Rates In Cool Stars Using Kepler Cluster Data

    NASA Astrophysics Data System (ADS)

    Saar, Steven

    Strong solar flares can damage power grids, satellites, interrupt communications and GPS information, and threaten astronauts and high latitude air travelers. Despite the potential cost, their frequency is poorly determined. Beyond purely current terrestrial concerns, how the rate of large flares (and associated coronal mass ejections [CMEs], high-energy particle fluxes and far UV emission) varies over the stellar lifetime holds considerable astrophysical interest. These include: the contributions of flares to coronal energy budgets; the importance of flares and CMEs to terrestrial and exoplanet atmospheric and biological evolution; and importance of CME mass loss for angular momentum evolution. We will explore the rate of strong flares and its variation with stellar age, mass and rotation by studying Kepler data of cool stars in two open clusters NGC 6811 (age ~ 1 Gyr) and NGC 6819 (~2.5 Gyr). We will use two flare analysis methods to build white-light flare distributions for cluster stars. One subtracts a low-pass filtered version of the data and analyzes the residue for positive flux deviations, the other does a statistical analysis of the flux deviations vs. time lags compared with a model. For near- solar stars, a known solar relation can then be used to estimate X-ray production by the white-light flares. For stars much hotter or cooler or with significantly different chromospheric density, we will use particle code flare models including bombardment effects to estimate how the X-ray to white light scaling changes. With the X-ray values, we can estimate far UV fluxes and CME rates, building a picture of the flare effects; with the two cluster ages, we can make a first estimate of the solar rate (by projecting to the Sun's age) and begin to build up an understanding of flare rate evolution with mass and age. Our proposal falls squarely in the "Stellar Astrophysics and Exoplanets" research area, and is relevant to NASA astrophysics goals in promoting better

  13. Corrosion and passivation behavior of Mg-Zn-Y-Al alloys prepared by cooling rate-controlled solidification

    NASA Astrophysics Data System (ADS)

    Yamasaki, Michiaki; Izumi, Shogo; Kawamura, Yoshihito; Habazaki, Hiroki

    2011-07-01

    Highly corrosion-resistant nanocrystalline Mg-Zn-Y-Al multi-phase alloys have been prepared by consolidation of rapidly solidified (RS) ribbons. The relation between corrosion behavior and microstructure evolution of Mg-Zn-Y-Al alloys with a long period stacking ordered phase has been investigated. In order to clarify the influence of rapid solidification on the occurrence of localized corrosion such as filiform corrosion, several Mg 96.75Zn 0.75Y 2Al 0.5 (at.%) alloys with different cooling rates are fabricated by the gravity casting, copper mould injection casting and melt-spinning techniques and their corrosion behavior and microstructures are examined by the salt water immersion test, electrochemical measurements, GDOES, XRD, SEM and TEM. To clarify the effect of aluminium addition on the improvement in corrosion resistance of the alloys, several Mg 97.25- xZn 0.75Y 2Al x alloys with different aluminium contents are fabricated by consolidating RS ribbons and the formation of corroded films on the Mg-Zn-Y-Al alloys have been investigated. Rapid solidification brings about the grain refinement and an increase in the solid solubility of zinc, yttrium and aluminium into the magnesium matrix, enhancing microstructural and electrochemical homogeneity, which in turn enhanced corrosion resistance. The addition of aluminium to magnesium can modify the structure and chemical composition of surface films and improves the resistance to local breakdown of the films.

  14. Estimation of Mass-Loss Rates from Emission Line Profiles in the UV Spectra of Cool Stars

    NASA Technical Reports Server (NTRS)

    Carpenter, K. G.; Robinson, R. D.; Harper, G. M.

    1999-01-01

    The photon-scattering winds of cool, low-gravity stars (K-M giants and supergiants) produce absorption features in the strong chromospheric emission lines. This provides us with an opportunity to assess important parameters of the wind, including flow and turbulent velocities, the optical depth of the wind above the region of photon creation, and the star's mass-loss rate. We have used the Lamers et al. Sobolev with Exact Integration (SEI) radiative transfer code along with simple models of the outer atmospheric structure to compute synthetic line profiles for comparison with the observed line profiles. The SEI code has the advantage of being computationally fast and allows a great number of possible wind models to be examined. We therefore use it here to obtain initial first-order estimates of the wind parameters. More sophisticated, but more time-consuming and resource intensive calculations will be performed at a later date, using the SEI-deduced wind parameters as a starting point. A comparison of the profiles over a range of wind velocity laws, turbulence values, and line opacities allows us to constrain the wind parameters, and to estimate the mass-loss rates. We have applied this analysis technique (using lines of Mg II, 0 I, and Fe II) so far to four stars: the normal K5-giant alpha Tau, the hybrid K-giant gamma Dra, the K5 supergiant lambda Vel, and the M-giant gamma Cru. We present in this paper a description of the technique, including the assumptions which go into its use, an assessment of its robustness, and the results of our analysis.

  15. Thermal History of São João Nepomuceno (IVA) Iron Meteorite Inferred from Ganguly's Cooling Rate Model and 57Fe Mössbauer Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    dos Santos, E.; Scorzelli, R. B.; Varela, M. E.

    2016-08-01

    The intracrystalline Fe-Mg distribution in orthopyroxenes, as measured by means of 57Fe Mössbauer spectroscopy and associated to Ganguly’s cooling rate numerical method, are used to infer the thermal history of São João Nepomuceno (IVA) meteorite.

  16. Investigations on the heat transport capability of a cryogenic oscillating heat pipe and its application in achieving ultra-fast cooling rates for cell vitrification cryopreservation☆

    PubMed Central

    Han, Xu; Ma, Hongbin; Jiao, Anjun; Critser, John K.

    2010-01-01

    Theoretically, direct vitrification of cell suspensions with relatively low concentrations (~1 M) of permeating cryoprotective agents (CPA) is suitable for cryopreservation of almost all cell types and can be accomplished by ultra-fast cooling rates that are on the order of 106–7 K/min. However, the methods and devices currently available for cell cryopreservation cannot achieve such high cooling rates. In this study, we constructed a novel cryogenic oscillating heat pipe (COHP) using liquid nitrogen as its working fluid and investigated its heat transport capability to assess its application for achieving ultra-fast cooling rates for cell cryopreservation. The experimental results showed that the apparent heat transfer coefficient of the COHP can reach 2 × 105 W/m2·K, which is two orders of the magnitude higher than traditional heat pipes. Theoretical analyzes showed that the average local heat transfer coefficient in the thin film evaporation region of the COHP can reach 1.2 × 106 W/m2·K, which is approximately 103 times higher than that achievable with standard pool-boiling approaches. Based on these results, a novel device design applying the COHP and microfabrication techniques is proposed and its efficiency for cell vitrification is demonstrated through numerical simulation. The estimated average cooling rates achieved through this approach is 106–7 K/min, which is much faster than the currently available methods and sufficient for achieving vitrification with relatively low concentrations of CPA. PMID:18430413

  17. Effect of Cooling Rate on the Microstructure and Mechanical Properties of Sn-1.0Ag-0.5Cu-0.2BaTiO3 Composite Solder

    NASA Astrophysics Data System (ADS)

    Yang, Li; Ge, Jinguo; Liu, Haixiang; Xu, Liufeng; Bo, Anbing

    2015-11-01

    The microstructure, interfacial intermetallic compound (IMC) layer, microhardness, tensile properties, and fracture surfaces of Sn-1.0Ag-0.5Cu-0.2BaTiO3 composite solder were explored under three different cooling conditions (water-, air-, and furnace-cooled) during solidification. The average grain size was refined and the volume fraction of primary β-Sn dendrites increased with increasing cooling rate. The thickness of the IMC layer increased as the cooling rate was decreased, and the morphology also transformed from scallop shaped, for a rapid cooling rate, to irregular shaped for slower cooling; a Cu3Sn IMC layer was detected between the Cu6Sn5 IMC and copper substrate under the furnace-cooled condition, but not in water- or air-cooled specimens. The mechanical properties, including the microhardness and tensile properties, improved with rapid solidification due to the combined effects of grain refinement and a secondary strengthening mechanism. Fracture surfaces after tensile tests showed that the amount of dimples decreased and a cleavage-like pattern increased as the cooling rate was decreased from the water-cooled to furnace-cooled condition, so the fracture process transformed from ductile to mixed-mode fracture. A refined microstructure and excellent mechanical properties were obtained for the rapidly cooled sample.

  18. Influence of thrust belt geometry and shortening rate on thermochronometer cooling ages: Insights from thermokinematic and erosion modeling of the Bhutan Himalaya

    NASA Astrophysics Data System (ADS)

    McQuarrie, Nadine; Ehlers, Todd A.

    2015-06-01

    Advancements in thermochronology and numerical modeling offer the potential to associate the age of thermochronometric samples to both exhumational and deformational processes. However, understanding how these components are related in compressional systems requires linking the geometry and magnitude of fault slip to the distribution and amount of erosion. To address this, we apply a 2-D thermokinematic model to a forward modeled balanced cross section to quantify the cooling history in fold-thrust belt settings. The restored cross section provides a kinematic path of rocks and structures necessary to reproduce the surface geology. By assigning ages to displacement amounts, we produced a range of potential velocity vectors used to calculate heat transport, erosion, and rock cooling. We test the predicted ages against a suite of previously published thermochronometric data from the Bhutan Himalaya to explore the utility of the data to constrain the timing, rate, and geometry of fault motion as well as variations in the exhumation rate. We evaluate the cooling history associated with a constant rate of shortening of 18 mm/yr, rates that are 2.0, 1.5, 0.75, and 0.5 times the constant rate, and rates that vary with time to determine which kinematic history best matches the measured cooling ages. The combination of relatively old apatite fission track and zircon (U-Th)/He measured ages and younger (15-9 Ma) 40Ar/39Ar ages from white mica is best matched with faster rates (relative to constant rates) between 11.5 and 8 Ma and slower than constant rates from 17 to 11.5 Ma and 8 Ma to present.

  19. Cooling rate correction and Detection of mineralogical evolution during Thellier-Thellier's experiments on baked clays. Applications to French protohistoric structures

    NASA Astrophysics Data System (ADS)

    Lanos, P.; Hervé, G.; Chauvin, A.; Perron d'Arc, M.

    2011-12-01

    Archaeointensity protocols have been considerably improved since the last years to better detect multidomain (MD) grains effects or mineralogical evolutions during Thellier's experiments. Current published data respect more strict criteria and take into account the anisotropy of thermoremanent magnetization (TRM). However the effect of the cooling rate on the intensity of the TRM acquired during cooling, which depends on the type of the ferromagnetic grains, remains difficult to precisely quantify. The main problem is to estimate the true cooling rate of the archeological structures and usually a 24 hours cooling is assumed. An experimental study of 35 small bricks baked in two kilns during summer 2007 and 2008 (in Sallèles d'Aude, southern France) gives new elements about the cooling rate correction. The used kilns are of two different sizes, similar to classical archaeological structures. Intensity of the geomagnetic field (43 μT) in the kilns and the temperature decrease during the cooling (around 12 hours for the small kiln and 70 hours for the other one) were measured. Discrepancies between the TRM intensity after fast (1.5 hour in the laboratory) and low cooling of 24 hours are over a very wide range between -5 and +30%. The use of the true cooling rate of the kilns (respectively 12 and 72 hours) gives mean archaeointensities (43.8±1.8 μT and 42.7±2.2 μT) corresponding to the intensity of the field measured within them. By applying the usual cooling of 24 hours, the intensity of the field is underestimated by 3 μT in the small kiln and is overestimated by 3 μT in the bigger kiln. Consequently, a wrong cooling rate correction may explain the dispersion between archaeointensities. The second aspect of the presentation corresponds to the detection of mineralogical evolution during successive heatings of the Thellier-Thellier's protocol. This problem is particularly important for the millennia BC in Europe, as very well heated structures are less common

  20. Palm-based diacylglycerol fat dry fractionation: effect of crystallisation temperature, cooling rate and agitation speed on physical and chemical properties of fractions.

    PubMed

    Ab Latip, Razam; Lee, Yee-Ying; Tang, Teck-Kim; Phuah, Eng-Tong; Lee, Choon-Min; Tan, Chin-Ping; Lai, Oi-Ming

    2013-01-01

    Fractionation which separates the olein (liquid) and stearin (solid) fractions of oil is used to modify the physicochemical properties of fats in order to extend its applications. Studies showed that the properties of fractionated end products can be affected by fractionation processing conditions. In the present study, dry fractionation of palm-based diacylglycerol (PDAG) was performed at different: cooling rates (0.05, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0°C/min), end-crystallisation temperatures (30, 35, 40, 45 and 50°C) and agitation speeds (30, 50, 70, 90 and 110 rpm) to determine the effect of these parameters on the properties and yield of the solid and liquid portions. To determine the physicochemical properties of olein and stearin fraction: Iodine value (IV), fatty acid composition (FAC), acylglycerol composition, slip melting point (SMP), solid fat content (SFC), thermal behaviour tests were carried out. Fractionation of PDAG fat changes the chemical composition of liquid and solid fractions. In terms of FAC, the major fatty acid in olein and stearin fractions were oleic (C18:1) and palmitic (C16:0) respectively. Acylglycerol composition showed that olein and stearin fractions is concentrated with TAG and DAG respectively. Crystallization temperature, cooling rate and agitation speed does not affect the IV, SFC, melting and cooling properties of the stearin fraction. The stearin fraction was only affected by cooling rate which changes its SMP. On the other hand, olein fraction was affected by crystallization temperature and cooling rate but not agitation speed which caused changes in IV, SMP, SFC, melting and crystallization behavior. Increase in both the crystallization temperature and cooling rate caused a reduction of IV, increment of the SFC, SMP, melting and crystallization behaviour of olein fraction and vice versa. The fractionated stearin part melted above 65°C while the olein melted at 40°C. SMP in olein fraction also reduced to a range of 26 to

  1. Palm-based diacylglycerol fat dry fractionation: effect of crystallisation temperature, cooling rate and agitation speed on physical and chemical properties of fractions

    PubMed Central

    Ab Latip, Razam; Lee, Yee-Ying; Tang, Teck-Kim; Phuah, Eng-Tong; Lee, Choon-Min; Tan, Chin-Ping

    2013-01-01

    Fractionation which separates the olein (liquid) and stearin (solid) fractions of oil is used to modify the physicochemical properties of fats in order to extend its applications. Studies showed that the properties of fractionated end products can be affected by fractionation processing conditions. In the present study, dry fractionation of palm-based diacylglycerol (PDAG) was performed at different: cooling rates (0.05, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0°C/min), end-crystallisation temperatures (30, 35, 40, 45 and 50°C) and agitation speeds (30, 50, 70, 90 and 110 rpm) to determine the effect of these parameters on the properties and yield of the solid and liquid portions. To determine the physicochemical properties of olein and stearin fraction: Iodine value (IV), fatty acid composition (FAC), acylglycerol composition, slip melting point (SMP), solid fat content (SFC), thermal behaviour tests were carried out. Fractionation of PDAG fat changes the chemical composition of liquid and solid fractions. In terms of FAC, the major fatty acid in olein and stearin fractions were oleic (C18:1) and palmitic (C16:0) respectively. Acylglycerol composition showed that olein and stearin fractions is concentrated with TAG and DAG respectively. Crystallization temperature, cooling rate and agitation speed does not affect the IV, SFC, melting and cooling properties of the stearin fraction. The stearin fraction was only affected by cooling rate which changes its SMP. On the other hand, olein fraction was affected by crystallization temperature and cooling rate but not agitation speed which caused changes in IV, SMP, SFC, melting and crystallization behavior. Increase in both the crystallization temperature and cooling rate caused a reduction of IV, increment of the SFC, SMP, melting and crystallization behaviour of olein fraction and vice versa. The fractionated stearin part melted above 65°C while the olein melted at 40°C. SMP in olein fraction also reduced to a range of 26 to

  2. Palm-based diacylglycerol fat dry fractionation: effect of crystallisation temperature, cooling rate and agitation speed on physical and chemical properties of fractions.

    PubMed

    Ab Latip, Razam; Lee, Yee-Ying; Tang, Teck-Kim; Phuah, Eng-Tong; Lee, Choon-Min; Tan, Chin-Ping; Lai, Oi-Ming

    2013-01-01

    Fractionation which separates the olein (liquid) and stearin (solid) fractions of oil is used to modify the physicochemical properties of fats in order to extend its applications. Studies showed that the properties of fractionated end products can be affected by fractionation processing conditions. In the present study, dry fractionation of palm-based diacylglycerol (PDAG) was performed at different: cooling rates (0.05, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0°C/min), end-crystallisation temperatures (30, 35, 40, 45 and 50°C) and agitation speeds (30, 50, 70, 90 and 110 rpm) to determine the effect of these parameters on the properties and yield of the solid and liquid portions. To determine the physicochemical properties of olein and stearin fraction: Iodine value (IV), fatty acid composition (FAC), acylglycerol composition, slip melting point (SMP), solid fat content (SFC), thermal behaviour tests were carried out. Fractionation of PDAG fat changes the chemical composition of liquid and solid fractions. In terms of FAC, the major fatty acid in olein and stearin fractions were oleic (C18:1) and palmitic (C16:0) respectively. Acylglycerol composition showed that olein and stearin fractions is concentrated with TAG and DAG respectively. Crystallization temperature, cooling rate and agitation speed does not affect the IV, SFC, melting and cooling properties of the stearin fraction. The stearin fraction was only affected by cooling rate which changes its SMP. On the other hand, olein fraction was affected by crystallization temperature and cooling rate but not agitation speed which caused changes in IV, SMP, SFC, melting and crystallization behavior. Increase in both the crystallization temperature and cooling rate caused a reduction of IV, increment of the SFC, SMP, melting and crystallization behaviour of olein fraction and vice versa. The fractionated stearin part melted above 65°C while the olein melted at 40°C. SMP in olein fraction also reduced to a range of 26 to

  3. Influence of cooling rate in planar thermally assisted magnetic random access memory: Improved writeability due to spin-transfer-torque influence

    SciTech Connect

    Chavent, A.; Ducruet, C.; Portemont, C.; Creuzet, C.; Alvarez-Hérault, J.; Vila, L.; Sousa, R. C.; Prejbeanu, I. L.; Dieny, B.

    2015-09-14

    This paper investigates the effect of a controlled cooling rate on magnetic field reversal assisted by spin transfer torque (STT) in thermally assisted magnetic random access memory. By using a gradual linear decrease of the voltage at the end of the write pulse, the STT decays more slowly or at least at the same rate as the temperature. This condition is necessary to make sure that the storage layer magnetization remains in the desired written direction during cooling of the cell. The influence of the write current pulse decay rate was investigated on two exchange biased synthetic ferrimagnet (SyF) electrodes. For a NiFe based electrode, a significant improvement in writing reproducibility was observed using a gradual linear voltage transition. The write error rate decreases by a factor of 10 when increasing the write pulse fall-time from ∼3 ns to 70 ns. For comparison, a second CoFe/NiFe based electrode was also reversed by magnetic field assisted by STT. In this case, no difference between sharp and linear write pulse fall shape was observed. We attribute this observation to the higher thermal stability of the CoFe/NiFe electrode during cooling. In real-time measurements of the magnetization reversal, it was found that Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling in the SyF electrode vanishes for the highest pulse voltages that were used due to the high temperature reached during write. As a result, during the cooling phase, the final state is reached through a spin-flop transition of the SyF storage layer.

  4. Influence of cooling rate in planar thermally assisted magnetic random access memory: Improved writeability due to spin-transfer-torque influence

    NASA Astrophysics Data System (ADS)

    Chavent, A.; Ducruet, C.; Portemont, C.; Creuzet, C.; Vila, L.; Alvarez-Hérault, J.; Sousa, R. C.; Prejbeanu, I. L.; Dieny, B.

    2015-09-01

    This paper investigates the effect of a controlled cooling rate on magnetic field reversal assisted by spin transfer torque (STT) in thermally assisted magnetic random access memory. By using a gradual linear decrease of the voltage at the end of the write pulse, the STT decays more slowly or at least at the same rate as the temperature. This condition is necessary to make sure that the storage layer magnetization remains in the desired written direction during cooling of the cell. The influence of the write current pulse decay rate was investigated on two exchange biased synthetic ferrimagnet (SyF) electrodes. For a NiFe based electrode, a significant improvement in writing reproducibility was observed using a gradual linear voltage transition. The write error rate decreases by a factor of 10 when increasing the write pulse fall-time from ˜3 ns to 70 ns. For comparison, a second CoFe/NiFe based electrode was also reversed by magnetic field assisted by STT. In this case, no difference between sharp and linear write pulse fall shape was observed. We attribute this observation to the higher thermal stability of the CoFe/NiFe electrode during cooling. In real-time measurements of the magnetization reversal, it was found that Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling in the SyF electrode vanishes for the highest pulse voltages that were used due to the high temperature reached during write. As a result, during the cooling phase, the final state is reached through a spin-flop transition of the SyF storage layer.

  5. A quantitative-metallographic study of the sintering behaviour of dolomite

    SciTech Connect

    Yeprem, H.A.; Tueredi, E.; Karagoez, S. . E-mail: karagoez@kou.edu.tr

    2004-07-15

    Grain growth of the MgO phase during sintering of natural dolomite from Selcuklu-Konya in Turkey was studied in the temperature range 1600-1700 deg. C. For comparison purposes, iron oxide (98.66% mill scale) was added up to 1.5%. The compositions of the phases formed during sintering were studied using X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy. Quantitative-metallographic analyses were performed on images taken by SEM. For the automatic image analysis of dolomite microstructures, material (atomic number) contrast with backscattered electrons (BSEs) was utilized because it yields higher phase contrast compared to secondary electrons (SEs). Iron oxide additions to dolomite result in dense dolomite structures at given sintering temperatures, where phases with low melting temperatures are developed. During liquid phase sintering, periclase is enriched with iron, which destabilizes the MgO phase. The relevant kinetic exponents for MgO in the natural doloma and 0.5% Fe{sub 2}O{sub 3} added doloma were 6 and 2, and the activation energies were 108 and 243 kJ/mol, respectively.

  6. Metallographic and hardness examinations of TMI-2 lower pressure vessel head samples

    SciTech Connect

    Korth, G. E.

    1994-03-01

    Fifteen steel samples were removed from the lower pressure vessel head of the damaged TMI-2 nuclear reactor to assess the thermal threat to the head posed by 15 to 20 metric tons of molten core debris relocating there during the accident. Full sections of thirteen of the samples and partial sections of the other two samples underwent hardness and metallographic examinations at the Idaho National Engineering Laboratory. These examinations have shown that eleven of the fifteen samples did not exceed the ferrite-austenite transformation temperature of 727 C during the accident. The remaining four samples did show evidence of having a much more severe thermal history. The samples from core grid positions F-10 and G-8 are believed to have experienced temperatures of 1,040 to 1,060 C for about 30 minutes. Samples from positions E-8 and E-6 appear to have been subjected to 1,075 to 1,100 C for approximately 30 minutes.

  7. Low temperature mechanical properties, fractographic and metallographic evaluation of several alloy steels

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1973-01-01

    The mechanical properties are presented of alloy steels, 4130, 4140, 4340, 6150, and 8740. Test specimens were manufactured from approximately 1.00 inch (2.54 cm) diameter bar stock which had been heat treated to two different hardness levels. The following mechanical tests were performed at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C): (1) tensile test (Ultimate, yield, modulus, elongation, and reduction of area), (2) notched tensile test, (3) charpy V-notched impact test (impact energy), and (4) double shear strength test (ultimate and yield). The test data indicate excellent tensile strength, notched/unnotched tensile ratios, ductility, impact, and shear properties at all test temperatures, except at -200 F (-129 C) where the impact strength of the higher strength group of alloy steels, 4130 (Rc-37) and 4140 (Rc-44) decreased to approximately 9 ft. lbs. (12 joules) and 6 ft. lbs. (8 joules), respectively. Chemical, metallographic, and fractographic analyses were also performed to evaluate microstructure, microhardness and the effect of decrease in temperature on the ductile to brittle failure transition.

  8. Effect of cooling rate after hot rolling and of multistage strain aging on the drawability of low-carbon-steel wire rod

    NASA Astrophysics Data System (ADS)

    Taheri, A. Karimi; Maccagno, T. M.; Jonas, J. J.

    1995-05-01

    Tensile testing was used to simulate the multistage strain aging occurring in low-C steel during the relatively short intervals between dies in a multiple-die wire-drawing machine. The effects were examined of three simulated post-hot-rolling cooling rates and three thermal treatments on the strain-aging susceptibility of a high- and a low-N steel. This was measured by applying a 6 pct tensile strain, followed by aging at either 65° or 100 °C for 20 seconds, and then pulling the specimen to failure at room temperature. Increases in flow stress and decreases in the elongation to fracture both indicated high susceptibility to strain aging. It was found that the nitrogen content, the cooling rate from the hot-rolling temperature to about 300 °C, as well as the cooling rate below 300 °C, all have dramatic effects on the strain-aging behavior. Moreover, multistage strain aging is more severe than single-stage strain aging. The implications of these observations on increasing the drawability of low-carbon-steel wire are discussed.

  9. Metallographic anlaysis and strength investigation of different Be-Cu joints in the temperature range RT-3500C

    SciTech Connect

    Gervash, A.A.; Giniatouline, R.N.; Mazul, I.V.

    1995-09-01

    The goal of this work is to estimate the strength and structure of different Be-Cu joining techniques. Brazing, diffusion bonding and joint rolling methods were chosen as ITER Be-Cu joint method candidates. Selected for ITER application Be-Cu joints were produced as technological plates (30-50 mm x 50-100 mm x thickness). AR samples for farther investigations were cutted out from initial technological plates. To compare mechanical strength of selected Be-Cu joints tensile and shearing tests of chosen candidates were carried out in the temperature range RT - 350{degrees}C. The metallographic analysis of Be-Cu crosssection was also done. Preliminary results of these tests as well as metallographic analysis data are presented. The industrial possibilities of producing required for ITER full scale Be-Cu joints are discussed.

  10. Hydrogen film cooling of a small hydrogen-oxygen thrust chamber and its effect on erosion rates of various ablative materials

    NASA Technical Reports Server (NTRS)

    Hannum, N.; Roberts, W. E.; Russell, L. M.

    1977-01-01

    An experimental investigation was conducted to determine what arrangement of film-coolant-injection orifices should be used to decrease the erosion rates of small, high temperature, high pressure ablative thrust chambers without incurring a large penalty in combustion performance. All of the film cooling was supplied through holes in a ring between the outer row of injector elements and the chamber wall. The best arrangement, which had twice the number of holes as there were outer row injection elements, was also the simplest. The performance penalties, presented as a reduction in characteristic exhaust velocity efficiency, were 0.8 and 2.8 percentage points for the 10 and 20 percent cooling flows, respectively, The best film-coolant injector was then used to obtain erosion rates for 19 ablative materials. The throat erosion rate was reduced by a factor of 2.5 with a 10 percent coolant flow. Only the more expensive silica phenolic materials had low enough erosion rates to be considered for use in the nozzle throat. However, some of the cheaper materials might qualify for use in other areas of small nozzles with large throat diameters where the higher erosion rates are more acceptable.

  11. A metallographic technique for high temperature creep damage assessment in single crystal alloys

    SciTech Connect

    Henderson, P.; Komenda, J.

    1999-10-01

    The use of single crystal (SX) nickel-base superalloys will increase in the future with the introduction of SX blades into large gas turbines for base-load electricity production. Prolonged periods of use at high temperatures may cause creep deformation and the assessment of damage can give large financial savings. A number of techniques can be applied for life assessment, e.g., calculations based on operational data, nondestructive testing for material interrogation, but because of the uncertainties involved the techniques are often used in combination. This paper describes a material interrogation (metallographic) technique for creep strain assessment in SX alloys. Creep tests have been performed at 950 C on the SX alloy CMSX-4 and quantitative microstructural studies performed on specimens interrupted at various levels of strain. It was found that the strengthening {gamma}{prime}-particles, initially cuboidal in shape, coalesced to form large plates or rafts normal to the applied stress. The rafts reached their maximum length before 2% strain, but continued to thicken with increasing strain. Although of different dimensions, the aspect ratios (length/thickness ratio) of the gamma-prime rafts and gamma plates were similar at similar levels of strain, increasing from {approximately} 1 at zero strain to a maximum of {approximately} 3 at about 1--2% strain. Analysis of microstructural measurements from rafting studies on SX alloys presented in the literature showed that the aspect ratios of the {gamma} and {gamma}{prime}-phases were similar and that at a temperature of 950--1,000 C a maximum length/thickness ratio of about 2.5--3.5 is reached at 1 to 2% creep strain. Measurement of gamma-prime raft or (or gamma plate) dimensions on longitudinal sections of blades is thus a suitable method for high temperature creep damage assessment of SX alloys.

  12. Optimum Conditions for the Efficacy and Safety of Cryofiltration Apheresis: An Analysis of Circuit Temperatures Depending on Plasma Flow Rate and Cooling Coil Lengths/Turns.

    PubMed

    Nakajima, Hirofumi; Kaneko, Shuzo; Sato, Yukihiro; Takano, Tomoo; Hosino, Toshihisa

    2015-08-01

    A system providing both appropriate cooling and warming are needed for the efficacy and safety of cryofiltration (CF) plasmapheresis. We measured some points of CF circuit temperatures with varying plasma flow rates (QP  = 10-40 mL/min) and the numbers of connecting cooling coils (one or two) under the conditions of blood flow rate (QB ) 100 mL/min with 7700-mm coil length, 19 turns, and 50-mL priming volume. We measured the respective temperatures of each point of starting/returning for an extracorporeal circuit (TA /TV ), intracooling coil (TC ), and post-plasma fractionator (PF) (TPF ). The subtraction of TV from TA (ΔT) was used as an indicator of safe return. There were no significant differences in TC , TPF , or ΔT in accordance with each QP between that of one and two coils. All of the Tc values under the condition QP  ≤ 20 mL/min achieved <4°C. The TPF under the condition QP  ≥ 20 mL/min was not significantly different compared to that of QP 30 mL/min (the lowest condition). Although the ΔT increased depending on the QP increase, the ΔT under the condition QP  ≤ 15 mL/min was not significantly different from that of the control (one-way double-filtration plasmapheresis [DFPP]) group. We conclude that (i) one coil is enough for effective cooling in CF, and (ii) an ideal QP that fulfills the required conditions for both effective cooling and sufficient warming of returning fluid does not exist, but QP from 15 to 20 mL/min may be a relevant range.

  13. Groundmass crystallisation and cooling rates of lava-like ignimbrites: the Grey's Landing ignimbrite, southern Idaho, USA

    NASA Astrophysics Data System (ADS)

    Ellis, B. S.; Cordonnier, B.; Rowe, M. C.; Szymanowski, D.; Bachmann, O.; Andrews, G. D. M.

    2015-10-01

    Constraining magmatic and eruptive processes is key to understanding how volcanoes operate. However, reconstructing eruptive and pre-eruptive processes requires the ability to see through any post-eruptive modification of the deposit. The well-preserved Grey's Landing ignimbrite from the central Snake River Plain provides an opportunity to systematically investigate the post-eruptive processes occurring through a single deposit sheet. Despite overall compositional homogeneity in both bulk and glass compositions, the Grey's Landing ignimbrite does preserve differences in the abundance of Li in plagioclase crystals which are strongly associated with the host lithology. Li abundances in plagioclase from the quickly cooled upper and basal vitrophyres are typically low (average 5 ppm, n = 262) while plagioclase from the microcrystalline interior of the deposit has higher Li contents (average 33 ppm, n = 773). Given that no other trace elemental parameter in plagioclase varies, we interpret the variability in Li to reflect a post-depositional process. Groundmass crystallisation of a rhyolite like Grey's Landing requires ˜50 % crystallisation of sanidine and variable amounts of a silica-rich phase (quartz, tridymite, cristobalite) and plagioclase to satisfy mass balance. We suggest the low affinity of Li for sanidine causes migration of groundmass Li into plagioclase during crystallisation. Even within the microcrystalline interior of the deposit, the morphology of the groundmass varies. The more marginal, finer-grained regions are dominated by cristobalite as the SiO2-rich phase while tridymite and quartz are additionally found in the more slowly cooled, coarser-grained portions of thick sections of the ignimbrite. Numerical models of cooling and crystallisation tested against field observations indicate that the groundmass crystallisation occurred relatively rapidly following emplacement (a maximum of a few years where the ignimbrite is thickest). These numerical

  14. Effects of cooling rate and Al on MnS formation in medium-carbon non-quenched and tempered steels

    NASA Astrophysics Data System (ADS)

    Li, Meng-long; Wang, Fu-ming; Li, Chang-rong; Yang, Zhan-bing; Meng, Qing-yong; Tao, Su-fen

    2015-06-01

    The effect of Al on the morphology of MnS in medium-carbon non-quenched and tempered steel was investigated at three different cooling rates of 0.24, 0.43, and 200°C·s-1. The formation mechanisms of three types of MnS were elucidated based on phase diagram information combined with crystal growth models. The morphology of MnS is governed by the precipitation mode and the growth conditions. A monotectic reaction and subsequent fast solidification lead to globular Type I MnS. Type II MnS inclusions with different morphological characteristics form as a result of a eutectic reaction followed by the growth in the Fe matrix. Type III MnS presents a divorced eutectic morphology. At the cooling rate of 0.24°C·s-1, the precipitation of dispersed Type III MnS is significantly enhanced by the addition of 0.044wt% acid-soluble Al (Als), while Type II MnS clusters prefer to form in steels with either 0.034wt% or 0.052wt% Als. At the relatively higher cooling rates of 200°C·s-1 and 0.43°C·s-1, the formation of Type I and Type II MnS inclusions is promoted, and the influence of Al is negligible. The results of this work are expected to be employed in practice to improve the mechanical properties of non-quenched and tempered steels.

  15. A possible difference in cooling rates recorded in REE in coexisting pyroxenes in peridotites from supra-subduction ophiolites and mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Dygert, N. J.; Liang, Y.; Kelley, K. A.

    2013-12-01

    Recently a REE-in-two-pyroxene thermometer was developed for mafic and ultramafic rocks [1]. This new thermometer is based on temperature sensitive REE partition coefficients between coexisting pyroxenes and calibrated against laboratory partitioning data. Because REE diffusion rates in pyroxene are relatively slow, the thermometer reads a higher temperature than major element based pyroxene thermometers. The difference between major and trace element derived temperatures depends primarily on cooling rate. Here we report new trace element data for peridotites from Trinity and Josephine ophiolites and a modern supra-subduction zone (SSZ) ophiolite analogue (the Mariana trench) determined by laser ablation ICP-MS. We inverted temperatures from the new data and globally distributed ophiolitic peridotite from eight literature studies (Figure 1). Data quality was carefully monitored leaving temperatures from 65 samples. Individual ophiolites usually have temperatures clustered within a range of a few hundred degrees, but the temperature range for the global dataset is greater than 700°C (688-1401°C). Temperatures calculated for the same samples using the two pyroxene thermometer of Brey and Köhler [2] are considerably lower (564-1049°C). REE temperatures are plotted against the major element temperatures [2] in Figure 1. Abyssal peridotites reported in [1] are shown by the peach field. Much of the ophiolite data plots farther from the blue 1:1 line than the abyssal peridotites, suggesting SSZ lithospheric mantle may cool more rapidly at those ophiolites. Fast cooling can be attributed to one or more dynamic differences between mid-ocean ridge (MOR) environments and supra-subduction environments, such as enhanced hydrothermal circulation, thinner oceanic crust, or rapid cooling due to basin closure and obduction. We note that several ophiolites appear to cool more slowly than the abyssal peridotites, however in those samples geochemical evidence suggests secondary

  16. Effect of the cooling rate on the mechanism and the kinetics of the phase transformations in solidification of W-Mo high-speed steels

    SciTech Connect

    Nizhnikovskaya, P.F.; Kalinushkin, E.P.; Arshava, E.V.; Yakushev, O.S.

    1988-03-01

    The stop-quenching solidification of steel R6M5, R6M5F3, R6M5K5 was studied. The furnace was a horizontal-type vacuum with a quenching tank provided with a thyristor system. The specimens were examined by optical and scanning electron microscopy and also by electron microprobe. The method of stop-quenching was found to increase the cooling rate for a fuller completion of the peritectic reaction, establish a connection between the peritectic and the eutectic reaction in high speed steels, and broaden the temperature range of peritic transformation under conditions of accelerated heat removal.

  17. Feasibility assessment of vacuum cooling followed by immersion vacuum cooling on water-cooked pork.

    PubMed

    Dong, Xiaoguang; Chen, Hui; Liu, Yi; Dai, Ruitong; Li, Xingmin

    2012-01-01

    Vacuum cooling followed by immersion vacuum cooling was designed to cool water-cooked pork (1.5±0.05 kg) compared with air blast cooling (4±0.5°C, 2 m/s), vacuum cooling (10 mbar) and immersion vacuum cooling. This combined cooling method was: vacuum cooling to an intermediate temperature of 25°C and then immersion vacuum cooling with water of 10°C to the final temperature of 10°C. It was found that the cooling loss of this combined cooling method was significantly lower (P<0.05) than those of air blast cooling and vacuum cooling. This combined cooling was faster (P<0.05) than air blast cooling and immersion vacuum cooling in terms of cooling rate. Moreover, the pork cooled by combined cooling method had significant differences (P<0.05) in water content, color and shear force.

  18. Metallographic Preparation of Space Shuttle Reaction Control System Thruster Electron Beam Welds for Electron Backscatter Diffraction

    NASA Technical Reports Server (NTRS)

    Martinez, James

    2011-01-01

    A Space Shuttle Reaction Control System (RCS) thruster failed during a firing test at the NASA White Sands Test Facility (WSTF), Las Cruces, New Mexico. The firing test was being conducted to investigate a previous electrical malfunction. A number of cracks were found associated with the fuel closure plate/injector assembly (Fig 1). The firing test failure generated a flight constraint to the launch of STS-133. A team comprised of several NASA centers and other research institutes was assembled to investigate and determine the root cause of the failure. The JSC Materials Evaluation Laboratory was asked to compare and characterize the outboard circumferential electron beam (EB) weld between the fuel closure plate (Titanium 6Al-4V) and the injector (Niobium C-103 alloy) of four different RCS thrusters, including the failed RCS thruster. Several metallographic challenges in grinding/polishing, and particularly in etching were encountered because of the differences in hardness, ductility, and chemical resistance between the two alloys and the bimetallic weld. Segments from each thruster were sectioned from the outboard weld. The segments were hot-compression mounted using a conductive, carbon-filled epoxy. A grinding/polishing procedure for titanium alloys was used [1]. This procedure worked well on the titanium; but a thin, disturbed layer was visible on the niobium surface by means of polarized light. Once polished, each sample was micrographed using bright field, differential interference contrast optical microscopy, and scanning electron microscopy (SEM) using a backscatter electron (BSE) detector. No typical weld anomalies were observed in any of the cross sections. However, areas of large atomic contrast were clearly visible in the weld nugget, particularly along fusion line interfaces between the titanium and the niobium. This prompted the need to better understand the chemistry and microstructure of the weld (Fig 2). Energy Dispersive X-Ray Spectroscopy (EDS

  19. Cooling rates and the depth of detachment faulting at oceanic core complexes: Evidence from zircon Pb/U and (U-Th)/He ages

    USGS Publications Warehouse

    Grimes, Craig B.; Cheadle, Michael J.; John, Barbara E.; Reiners, P.W.; Wooden, J.L.

    2011-01-01

    Oceanic detachment faulting represents a distinct mode of seafloor spreading at slow spreading mid-ocean ridges, but many questions persist about the thermal evolution and depth of faulting. We present new Pb/U and (U-Th)/He zircon ages and combine them with magnetic anomaly ages to define the cooling histories of gabbroic crust exposed by oceanic detachment faults at three sites along the Mid-Atlantic Ridge (Ocean Drilling Program (ODP) holes 1270D and 1275D near the 15??20???N Transform, and Atlantis Massif at 30??N). Closure temperatures for the Pb/U (???800??C-850??C) and (U-Th)/He (???210??C) isotopic systems in zircon bracket acquisition of magnetic remanence, collectively providing a temperature-time history during faulting. Results indicate cooling to ???200??C in 0.3-0.5 Myr after zircon crystallization, recording time-averaged cooling rates of ???1000??C- 2000??C/Myr. Assuming the footwalls were denuded along single continuous faults, differences in Pb/U and (U-Th)/He zircon ages together with independently determined slip rates allow the distance between the ???850??C and ???200??C isotherms along the fault plane to be estimated. Calculated distances are 8.4 ?? 4.2 km and 5.0 2.1 km from holes 1275D and 1270D and 8.4 ?? 1.4 km at Atlantis Massif. Estimating an initial subsurface fault dip of 50 and a depth of 1.5 km to the 200??C isotherm leads to the prediction that the ???850??C isotherm lies ???5-7 km below seafloor at the time of faulting. These depth estimates for active fault systems are consistent with depths of microseismicity observed beneath the hypothesized detachment fault at the TAG hydrothermal field and high-temperature fault rocks recovered from many oceanic detachment faults. Copyright 2011 by the American Geophysical Union.

  20. A case study demonstration of the soil temperature extrema recovery rates after precipitation cooling at 10-cm soil depth

    NASA Technical Reports Server (NTRS)

    Welker, Jean Edward

    1991-01-01

    Since the invention of maximum and minimum thermometers in the 18th century, diurnal temperature extrema have been taken for air worldwide. At some stations, these extrema temperatures were collected at various soil depths also, and the behavior of these temperatures at a 10-cm depth at the Tifton Experimental Station in Georgia is presented. After a precipitation cooling event, the diurnal temperature maxima drop to a minimum value and then start a recovery to higher values (similar to thermal inertia). This recovery represents a measure of response to heating as a function of soil moisture and soil property. Eight different curves were fitted to a wide variety of data sets for different stations and years, and both power and exponential curves were fitted to a wide variety of data sets for different stations and years. Both power and exponential curve fits were consistently found to be statistically accurate least-square fit representations of the raw data recovery values. The predictive procedures used here were multivariate regression analyses, which are applicable to soils at a variety of depths besides the 10-cm depth presented.

  1. The effect of multiple particle sizes on cooling rates of chondrules produced in large-scale shocks in the solar nebula

    NASA Astrophysics Data System (ADS)

    Morris, Melissa A.; Weidenschilling, Stuart J.; Desch, Steven J.

    2016-05-01

    Chondrules represent one of the best probes of the physical conditions and processes acting in the early solar nebula. Proposed chondrule formation models are assessed based on their ability to match the meteoritic evidence, especially experimental constraints on their thermal histories. The model most consistent with chondrule thermal histories is passage through shock waves in the solar nebula. Existing models of heating by shocks generally yield a good first-order approximation to inferred chondrule cooling rates. However, they predict prolonged heating in the preshock region, which would cause volatile loss and isotopic fractionation, which are not observed. These models have typically included particles of a single (large) size, i.e., chondrule precursors, or at most, large particles accompanied by micron-sized grains. The size distribution of solids present during chondrule formation controls the opacity of the affected region, and significantly affects the thermal histories of chondrules. Micron-sized grains evaporate too quickly to prevent excessive heating of chondrule precursors. However, isolated grains in chondrule-forming regions would rapidly coagulate into fractal aggregates. Preshock heating by infrared radiation from the shock front would cause these aggregates to melt and collapse into intermediate-sized (tens of microns) particles. We show that inclusion of such particles yields chondrule cooling rates consistent with petrologic and isotopic constraints.

  2. Is cooling still cool?

    PubMed

    Subramaniam, Ashwin; Tiruvoipati, Ravindranath; Botha, John

    2015-03-01

    Therapeutic hypothermia (TH), where patients are cooled to between 32°C and 36°C for a period of 12-24 hours and then gradually rewarmed, may reduce the risk of ischemic injury to cerebral tissue following a period of insufficient blood flow. This strategy of TH could improve mortality and neurological function in patients who have experienced out-of-hospital cardiac arrest (OOHCA). The necessity of TH in OOHCA was challenged in late 2013 by a fascinating and potentially practice changing publication, which found that targeting a temperature of 36°C had similar outcomes to cooling patients to 33°C. This article reviews the current literature and summarizes the uncertainties and questions raised when considering cooling of patients at risk of hypoxic brain injury. Irrespective of whether TH or targeted temperature management is deployed in patients at risk of hypoxic brain injury, it would seem that avoiding hyperpyrexia is important and that a more rigorous approach to neurological evaluation is mandated. PMID:25423577

  3. Electron cooling

    NASA Astrophysics Data System (ADS)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  4. Cooling in a compound bucket

    SciTech Connect

    Shemyakin, A.; Bhat, C.; Broemmelsiek, D.; Burov, A.; Hu, M.; /Fermilab

    2007-09-01

    Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results.

  5. Stochastic Cooling

    SciTech Connect

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  6. HST Studies of the Chromospheres, Wind, and Mass-Loss Rates of Cool Giant and Supergiant Stars

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth G.

    2000-01-01

    UV spectra of K-M giant and supergiant stars and of carbon stars have been acquired with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). These spectra have been used to measure chromospheric flow and turbulent velocities, study the acceleration of their stellar winds, acquire constraints on their outer atmospheric structure, and enable estimates of their mass-loss rates. Results from our observations of the giant stars Gamma Dra (K5 III hybrid), Alpha Tau (K5 III), Gamma Cru (M3.4 III), Mu Gem (M3 IIIab), and 30 Her (MG III), the supergiants Alpha Ori (M2 Iab) and Lambda Vel (K5 Ib), and the carbon stars TX Psc (NO; C6,2) and TW Hor (NO; C7,2) will be summarized and compared. The high resolution and wavelength accuracy of these data have allowed the direct measurement of the acceleration of the stellar winds in the chromospheres of several of these stars (from initial velocities of 3-9 km/s to upper velocities of 15-25 km/s) and of the chromospheric macroturbulence (-25-35 km/s). The high signal-to-noise and large dynamic range of these spectra have allowed the detection and identification of numerous new emission features, including weak C IV emission indicative of hot transition-region plasma in the non-coronal giant Alpha Tau, many new fluorescent lines of Fe II, and the first detection of fluorescent molecular hydrogen emission and of Ca II recombination lines in the UV spectrum of a giant star. The UV spectrum of two carbon stars have been studied with unprecedented resolution and reveal extraordinarily complicated Mg II lines nearly smothered by circumstellar absorptions. Finally, comparison of synthetic UV emission line profiles computed with the Lamers et al. (1987) Sobolev with Exact Integration (SEI) code with observations of chromospheric emission lines overlain with wind absorption features provides estimates of the mass-loss rates for four of these stars.

  7. Variations in transpiration rate and leaf cell turgor maintenance in saplings of deciduous broad-leaved tree species common in cool temperate forests in Japan.

    PubMed

    Saito, Takami; Tanaka, Tadashi; Tanabe, Hiromi; Matsumoto, Yoosuke; Morikawa, Yasushi

    2003-01-01

    To clarify mechanisms underlying variation in transpiration rate among deciduous broad-leaved tree species, we measured diurnal changes in stomatal conductance (gs) and leaf water potential, and calculated the maximum transpiration rate (Emax), leaf-specific hydraulic conductance (K(s-l)) and difference between the soil water potential and the daily minimum leaf water potential (Psis - Psi(l,min)). Pressure-volume (P-V) measurements were made on leaves. Saplings of eight broad-leaved tree species that are common in Japanese cool temperate forests were studied. Maximum transpiration rate varied significantly among species. There was a statistically significant difference in Psis - Psi(l,min), but not in K(s-l). Species with large Emax also had large Psis - Psi(l,min) and gs. The results of the P-V analyses showed that species with a large Psis - Psi(l,min) maintained turgor even at low leaf water potentials. The similar daily minimum leaf pressure potentials (Psip) across all eight species indicate that Psip values below this minimum are critical. Based on these results, we suggest that the leaf cell capacity for turgor maintenance strongly affects Psis - Psi(l,min) and consequently Emax via stomatal regulation.

  8. Evaporative Cooling Membrane Device

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis (Inventor); Moskito, John (Inventor)

    1999-01-01

    An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

  9. Metallographic study of articles of the Kamensk iron foundry and iron works produced in the 18th-20th centuries

    NASA Astrophysics Data System (ADS)

    Schastlivtsev, V. M.; Gizhevski, B. A.; Khlebnikova, Yu. V.; Naumov, S. V.; Egorova, L. Yu.

    2016-02-01

    Results have been presented for studies of the microstructure and chemical composition of a number of articles made of iron and cast iron at the Kamensk plant, which cover the period from the start of the production of iron on the territory of the city of Kamensk-Ural'skii at the turn of the 17th-18th centuries to the beginning of the 20th century. Differences in the composition of the Kamensk cast iron and modern grades of foundry cast iron have been established. Possible sources of technological difficulties and production waste at the Kamensk plant have been revealed. The potential of metallographic studies for the attribution of historical articles made of ferrous metals are shown.

  10. Shear Fracture of Dual Phase AHSS in the Process of Stamping: Macroscopic Failure Mode and Micro-level Metallographical Observation

    NASA Astrophysics Data System (ADS)

    Wang, Wurong; Wei, Xicheng; Yang, Jun; Shi, Gang

    2011-08-01

    Due to its excellent strength and formability combinations, dual phase (DP) steels offer the potential to improve the vehicle crashworthiness performance without increasing car body weight and have been increasingly used into new vehicles. However, a new type of crack mode termed as shear fracture is accompanied with the application of these high strength DP steel sheets. With the cup drawing experiment to identify the limit drawing ratio (LDR) of three DP AHSS with strength level from 600 MPa to 1000 MPa, the study compared and categorized the macroscopic failure mode of these three types of materials. The metallographical observation along the direction of crack was conducted for the DP steels to discover the micro-level propagation mechanism of the fracture.

  11. High-efficiency impurity activation by precise control of cooling rate during atmospheric pressure thermal plasma jet annealing of 4H-SiC wafer

    NASA Astrophysics Data System (ADS)

    Maruyama, Keisuke; Hanafusa, Hiroaki; Ashihara, Ryuhei; Hayashi, Shohei; Murakami, Hideki; Higashi, Seiichiro

    2015-06-01

    We have investigated high-temperature and rapid annealing of a silicon carbide (SiC) wafer by atmospheric pressure thermal plasma jet (TPJ) irradiation for impurity activation. To reduce the temperature gradient in the SiC wafer, a DC current preheating system and the lateral back-and-forth motion of the wafer were introduced. A maximum surface temperature of 1835 °C within 2.4 s without sample breakage was achieved, and aluminum (Al), phosphorus (P), and arsenic (As) activations in SiC were demonstrated. We have investigated precise control of heating rate (Rh) and cooling rate (Rc) during rapid annealing of P+-implanted 4H-SiC and its impact on impurity activation. No dependence of resistivity on Rh was observed, while increasing Rc significantly decreased resistivity. A minimum resistivity of 0.0025 Ω·cm and a maximum carrier concentration of 2.9 × 1020 cm-3 were obtained at Rc = 568 °C/s.

  12. The Cooling History and Structure of the Ordinary Chondrite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Benoit, P. H.; Sears, D. W. G.

    1996-01-01

    Most major meteorite classes exhibit significant ranges of metamorphism. The effects of metamorphism have been extensively characterized, but the heat source(s) and the metamorphic environment are unknown. Proposed beat sources include Al-26, Fe-60, electromagnetic induction, and impact. It is typically assumed that metamorphism occurred in parent bodies of some sort, but it uncertain whether these bodies were highly structured ("onion skins") or were chaotic mixes of material ("rubble piles"). The lack of simple trends of metallographic cooling rates with petrologic type has been considered supportive of both concepts. In this study, we use induced thermoluminescence (TL) as an indicator of thermal history. The TL of ordinary chondrites is produced by sodic feldspar, and the induced TL peak temperature is related to its crystallographic order/disorder. Ordered feldspar has TL peak temperatures of approx. 120 C, and disordered feldspar has TL peak temperatures of approx. 220 C. While ordered feldspar can be easily disordered in the laboratory by heating above 650 C and is easily quenched in the disordered form, producing ordered feldspar requires cooling at geologic cooling rates. We have measured the induced TL properties of 101 equilibrated ordinary chondrites, including 49 H, 29 L, and 23 LL chondrites. For the H chondrites there is an apparent trend of decreasing induced TL peak temperature with increasing petrologic type. H4 chondrites exhibit a tight range of TL peak temperatures, 190 C - 200 C, while H6 chondrites exhibit TL peak temperatures between 180 C and 190 C. H5 chondrites cover the range between H4 and H6, and also extend up to 210 C. Similar results are obtained for LL chondfiles and most L6 chondrites have lower induced TL peak temperatures than L5 chondrites.

  13. Corrosion management of PbCaSn alloys in lead-acid batteries: Effect of composition, metallographic state and voltage conditions

    NASA Astrophysics Data System (ADS)

    Rocca, E.; Bourguignon, G.; Steinmetz, J.

    Since several years, lead calcium-based alloys have supplanted lead antimony alloys as structural materials for positive grids of lead-acid batteries in many applications, especially for VRLA batteries. Nevertheless, the positive grid corrosion probably remains one of the causes of rapid and premature failure of lead-acid batteries. The objective of the present study is to present a comprehensive study of the PbCaSn alloy corrosion in function of their composition, metallographic state and voltage conditions (discharge, overcharge, floating and cycling conditions). For that, four alloys PbCaSn x wt.% (x = 0, 0.6, 1.2, 2) were synthesized in two extreme metallurgical conditions and tested by four electrochemical lab-tests. Weight loss measurements and analyses by SEM, EPMA and XRD allowed to monitor the oxidation tests and to characterize the corrosion layers after the oxidation tests. The results show that the tin level in PbCaSn alloys should be adapted on the calcium concentration and the rate of overageing process, to maintain the beneficial effect of tin in service during the battery lifetime. According to our results, a Sn/Ca ratio of 2.5 gives good corrosion resistance in all potential conditions. Nevertheless, when tin level is too high, the corrosion layers can peel off from the metal, which involves a lack of cohesion between the collector and the paste, in cycling conditions. The anodic potential undergone by the metal is a second main factor determining the corrosion, especially the floating conditions and the frequency of deep discharge and overcharge. Thus the adjustment of the charge controller parameters of a battery system is a necessity to increase the lifetime of the grids and maintain a good rechargeability.

  14. Cooling wall

    SciTech Connect

    Nosenko, V.I.

    1995-07-01

    Protecting the shells of blast furnaces is being resolved by installing cast iron cooling plates. The cooling plates become non-operational in three to five years. The problem is that defects occur in manufacturing the cooling plates. With increased volume and intensity of work placed on blast furnaces, heat on the cast iron cooling plates reduces their reliability that limits the interim repair period of blast furnaces. Scientists and engineers from the Ukraine studied this problem for several years, developing a new method of cooling the blast furnace shaft called the cooling wall. Traditional cast iron plates were replaced by a screen of steel tubes, with the area between the tubes filled with fireproof concrete. Before placing the newly developed furnace shaft into operation, considerable work was completed such as theoretical calculations, design, research of temperature fields and tension. Continual testing over many years confirms the value of this research in operating blast furnaces. The cooling wall works with water cooling as well as vapor cooling and is operating in 14 blast furnaces in the Ukraine and two in Russia, and has operated for as long as 14 years.

  15. Curve fits of predicted inviscid stagnation-point radiative heating rates, cooling factors, and shock standoff distances for hyperbolic earth entry

    NASA Technical Reports Server (NTRS)

    Suttles, J. T.; Sullivan, E. M.; Margolis, S. B.

    1974-01-01

    Curve-fit formulas are presented for the stagnation-point radiative heating rate, cooling factor, and shock standoff distance for inviscid flow over blunt bodies at conditions corresponding to high-speed earth entry. The data which were curve fitted were calculated by using a technique which utilizes a one-strip integral method and a detailed nongray radiation model to generate a radiatively coupled flow-field solution for air in chemical and local thermodynamic equilibrium. The range of free-stream parameters considered were altitudes from about 55 to 70 km and velocities from about 11 to 16 km.sec. Spherical bodies with nose radii from 30 to 450 cm and elliptical bodies with major-to-minor axis ratios of 2, 4, and 6 were treated. Powerlaw formulas are proposed and a least-squares logarithmic fit is used to evaluate the constants. It is shown that the data can be described in this manner with an average deviation of about 3 percent (or less) and a maximum deviation of about 10 percent (or less). The curve-fit formulas provide an effective and economic means for making preliminary design studies for situations involving high-speed earth entry.

  16. Timing and rate of granulite facies metamorphism and cooling from multi-mineral chronology on migmatitic gneisses, Sierras de La Huerta and Valle Fértil, NW Argentina

    NASA Astrophysics Data System (ADS)

    Gallien, Florian; Mogessie, Aberra; Bjerg, Ernesto; Delpino, Sergio; de Machuca, Brigida Castro; Thöni, Martin; Klötzli, Urs

    2010-01-01

    Migmatitic paragneisses of the Valle Fértil-La Huerta Ranges at the Western margin of the Sierras Pampeanas are composed of garnet-cordierite-plagioclase-biotite-quartz-bearing units that experienced peak metamorphic conditions of ca. 800 °C at 6-7 kbar. Based on petrological studies, pseudosection modeling and petrographic observations, an anticlockwise P- T path with a small pressure increment is proposed. Rare earth element LA-ICP-MS patterns acquired from rutile bearing garnets suggest a single stage of garnet growth at high- T at pressures above the ilmenite-rutile transition. U-Pb dating of zircon rims from the migmatites indicates two distinct metamorphic U-Pb ages of 525 ± 9 Ma and 478 ± 9 Ma. The older age is suggested to record an amphibolite facies event of the Pampean orogeny. The younger metamorphic age is contemporary with igneous zircons from metatonalites and pegmatites that yield 478 ± 4 Ma. We suggest that the prograde high- T metamorphic Famatinian event is associated with the emplacement of large magmatic bodies in which large-scale magmatic activity gave rise to an increased geothermal gradient of about 35 °C/km. Sm-Nd garnet ages of 447 ± 3 Ma indicate a time span of around 30 Ma for which temperatures above the garnet closure temperature prevailed. Using U-Pb, Sm-Nd and Rb-Sr isotope systems, a cooling rate of 3 to 6 °C/Myr is inferred.

  17. More accurate determination of the quantity of ice crystallized at low cooling rates in the glycerol and 1,2-propanediol aqueous solutions: comparison with equilibrium.

    PubMed

    Boutron, P

    1984-04-01

    It is generally assumed that when cells are cooled at rates close to those corresponding to the maximum of survival, once supercooling has ceased, above the eutectic melting temperature the extracellular ice is in equilibrium with the residual solution. This did not seem evident to us due to the difficulty of ice crystallization in cryoprotective solutions. The maximum quantities of ice crystallized in glycerol and 1,2-propanediol solutions have been calculated from the area of the solidification and fusion peaks obtained with a Perkin-Elmer DSC-2 differential scanning calorimeter. The accuracy has been improved by several corrections: better defined baseline, thermal variation of the heat of fusion of the ice, heat of solution of the water from its melting with the residual solution. More ice crystallizes in the glycerol than in the 1,2-propanediol solutions, of which the amorphous residue contains about 40 to 55% 1,2-propanediol. The equilibrium values are unknown in the presence of 1,2-propanediol. With glycerol, in our experiments, the maximum is first lower than the equilibrium but approaches it as the concentration increases. It is not completely determined by the colligative properties of the solutes.

  18. Cool Shelter

    ERIC Educational Resources Information Center

    Praeger, Charles E.

    2005-01-01

    Amid climbing energy costs and tightening budgets, administrators at school districts, colleges and universities are looking for all avenues of potential savings while promoting sustainable communities. Cool metal roofing can save schools money and promote sustainable design at the same time. Cool metal roofing keeps the sun's heat from collecting…

  19. Soil warming in a cool-temperate mixed forest with peat soil enhanced heterotrophic and basal respiration rates but Q10 remained unchanged

    NASA Astrophysics Data System (ADS)

    Aguilos, M.; Takagi, K.; Liang, N.; Watanabe, Y.; Goto, S.; Takahashi, Y.; Mukai, H.; Sasa, K.

    2011-07-01

    We conducted soil warming experiment in a cool-temperate forest with peat soil in northern Japan, during the snowless seasons of 2007-2009. Our objective was to determine whether or not the heterotrophic respiration rate and the temperature sensitivity would change by soil warming. We elevated the soil temperature by 3 °C at 5 cm depth by means of overhead infrared heaters and continuously measured soil CO2 fluxes by using a fifteen-channel automated chamber system. Trenching treatment was also carried out to separate heterotrophic respiration and root respiration from the total soil respiration. The fifteen chambers were divided into three groups each with five replications for the control, unwarmed-trenched, and warmed-trenched treatments. We found that heterotrophic respiration contributed 71 % of the total soil respiration with the remaining 29 % accounted to autotrophic respiration. Soil warming enhanced heterotrophic respiration by 74 % (mean 6.11 ± 3.07 S.D. μmol m-2 s-1) as compared to the unwarmed-trenched treatment (mean 3.52 ± 1.74 μmol m-2 s-1). Soil CO2 efflux, however, was weakly correlated with soil moisture, probably because the volumetric soil moisture (33-46 %) was within a plateau region for root and microbial activities. The enhancement in heterotrophic respiration with soil warming in our study suggests that global warming will accelerate the loss of carbon from forested peatlands more seriously than other upland forest soils. On the other hand, soil warming did not cause significant change in the temperature sensitivity, Q10, (2.79 and 2.74 determined using hourly efflux data for unwarmed- and warmed-trenched, respectively), but increased their basal respiration rate at 0 °C (0.93 and 1.21 μmol m-2 s-1, respectively). Results suggest that if we predict the soil heterotrophic respiration rate in future warmer environment using the current relationship between soil temperature and heterotrophic respiration, the rate can be underestimated.

  20. Correlation of thermophoretically-modified small particle diffusional deposition rates in forced convection systems with variable properties, transpiration cooling and/or viscous dissipation

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.; Rosner, D. E.

    1984-01-01

    A cooled object (heat exchanger tube or turbine blade) is considered to be immersed in a hot fluid stream containing trace amounts of suspended vapors and/or small particles. Numerical prediction calculations were done for self-similar laminar boundary layers and law-of-the-wall turbulent boundary layers. Correlations are presented for the effect of thermophoresis in the absence of transpiration cooling and viscous dissipation; the effect of real suction and blowing in the absence of thermophoresis; the effect of viscous dissipation on thermophoresis in the absence of transpiration cooling; and the combined effect of viscous dissipation and transpiration cooling on thermophoresis. The final correlation, St/St-sub-zero, is insensitive to particle properties, Euler number, and local mainstream temperature.

  1. Cooled railplug

    DOEpatents

    Weldon, William F.

    1996-01-01

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers.

  2. Metallographic Analysis of Brush Bristle and Integrity Testing of Brush Seal in Shroud Ring of T-700 Engine

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George A.; Bill, Robert C.; Hull, David R.; Csavina, Kristine R.

    1995-01-01

    Post-test investigation of a T-700 engine brush seal found regions void of bristles ('yanked out'), regions of bent-over bristles near the inlet, some 'snapped' bristles near the fence, and a more uniform 'smeared' bristle interface between the first and last axial rows of bristles. Several bristles were cut from the brush seal, wax mounted, polished, and analyzed. Metallographic analysis of the bristles near the rub tip showed tungsten-rich phases uniformly distributed throughout the bristle with no apparent change within 1 to 2 micron of the interface except for possibly a small amount of titanium, which would represent a transfer from the rotor. Analysis of the bristle wear face showed nonuniform tungsten, which is indicative of material resolidification. The cut end contained oxides and internal fractures; the worn end was covered with oxide scale. Material losses due to wear and elastoplastic deformation within the shear zone and third-body lubrication effects in the contact zone are discussed.

  3. Metallographic examinations of Type 304 stainless steel (heat 9T2796) tested in high-temperature uniaxial and multiaxial experiments

    SciTech Connect

    Swindeman, R.W.; Houck, C.W.

    1984-03-01

    The results obtained from a number of metallographic examinations of Type 304 stainless steel specimens were compiled. Samples were obtained from uniaxial and multiaxial tests covering a very broad span of temperatures and times. Special emphasis was on the identification of failure modes, cracking patterns, grain distortion, and grain-boundary microstructures. Uniaxial specimens exhibited the following sequence of failure modes with increasing temperature and time: ductile plastic tearing, ductile plastic shear, wedge cracking, and microvoid cracking. Over most of the temperature range examined (482 to 871/sup 0/C), M/sub 23/C/sub 6/ precipitated on grain boundaries at long times. Sigma phase and possibly ferrite were often present in the stressed areas at temperatures as low as 482/sup 0/C (900/sup 0/F). These metallurgical features promoted a severe loss in creep ductility at long times and low temperatures. Most multiaxial tests were performed under conditions that promoted wedge cracking. Stress gradients also favored surface crack initiation rather than bulk damage. Testing times for multiaxial tests were less than 10,000 h; hence, there was insufficient time for the development of embrittling features such as microvoids, sigma, and ferrite. Long-time multiaxial tests to failure are recommended.

  4. Design and implementation of automatic opto-electrical detection system for spheroidal graphite cast iron metallographic phase

    NASA Astrophysics Data System (ADS)

    Meng, Qing-xin; Xiao, Ze-xin; Deng, Shi-chao

    2010-11-01

    Spheroidal graphite cast iron,with excellent mechanical properties,is widely used in manufacturing many advanced castings,such as crankshaft,gears,pistons,and a variety of machine parts.Its microstructure morphology reflects the quality performance of the products,which leads to an urgent need for a simple,accurate and automatic microstructure morphology detection technique for detecting the quality of spheroidal graphite cast iron.In this paper,opto-electrical detection technique is employed for designing a spheroidal graphite cast iron microstructure automatic detection system,in which the microstructure is imaged by optical microscopy system,and the digital images are obtained by industrial cameras and sent to the computer.A series of digital image processing algorithms,including gray transformation, binarization,edge detection,image morphology and seed filling etc,are adopted to calculate and analyze the microstructure images.The morphology and microstructure analysis methods are combined to obtain the characteristic parameters such as the size of the graphite,the ball classification,the number of graphite nodules and so on.The experiment results show that this method is simple,fast,and accurate and can be employed for assessment of the spheroidal graphite cast iron metallographic phase instead of manual detection.

  5. Cool Vest

    NASA Technical Reports Server (NTRS)

    1982-01-01

    ILC, Dover Division's lightweight cooling garment, called Cool Vest was designed to eliminate the harmful effects of heat stress; increases tolerance time in hot environments by almost 300 percent. Made of urethane-coated nylon used in Apollo, it works to keep the body cool, circulating chilled water throughout the lining by means of a small battery-powered pump. A pocket houses the pump, battery and the coolant which can be ice or a frozen gel, a valve control allows temperature regulation. One version is self-contained and portable for unrestrained movement, another has an umbilical line attached to an external source of coolant, such as standard tap water, when extended mobility is not required. It is reported from customers that the Cool Vest pays for itself in increased productivity in very high temperatures.

  6. Cool School.

    ERIC Educational Resources Information Center

    Stephens, Suzanne

    1980-01-01

    The design for Floyd Elementary School in Miami (Florida) seeks to harness solar energy to provide at least 70 percent of the annual energy for cooling needs and 90 percent for hot water. (Author/MLF)

  7. Extreme rapid warming yields high functional survivals of vitrified 8-cell mouse embryos even when suspended in a half-strength vitrification solution and cooled at moderate rates to −196°C✰

    PubMed Central

    Seki, Shinsuke; Jin, Bo; Mazu, Peter

    2014-01-01

    To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to do so is to subject them to procedures that convert cell water into a non-crystalline glass. Current belief is that to achieve this vitrification, cells must be suspended in very high concentrations of glass-inducing solutes (i.e., ≥ 6 molal) and cooled at very high rates (i.e., >> 1,000°C/min). We report here that both these beliefs are incorrect with respect to the vitrification of 8-cell mouse embryos. In this study, precompaction 8-cell embryos were vitrified in several dilutions of EAFS10/10 using various cooling rates and warming rates. Survival was based on morphology, osmotic functionality, and on the ability to develop to expanded blastocysts. With a warming rate of 117,500°C/min, the percentages of embryos vitrified in 1×, 0.75×, and 0.5× EAFS that developed to blastocysts were 93%, 92%, and 86%, respectively. And the percentages of morphological survivors that developed to expanded blastocysts were 100%, 92%, and 97%, respectively. Even when the solute concentration of the EAFS was reduced to 33% of normal, we obtained 40% functional survival of these 8-cell embryos. PMID:24333434

  8. A study on the effect of various design parameters on the natural circulation flow rate of the ex-vessel core catcher cooling system of EU-APR1400

    SciTech Connect

    Rhee, B. W.; Ha, K. S.; Park, R. J.; Song, J. H.

    2012-07-01

    In this paper, a study on the effect of various design parameters such as the channel gap width, heat flux distribution, down-comer pipe size and two-phase flow slip ratio on the natural circulation flow rate is performed based on a physical model for a natural circulation flow along the flow path of the ex-vessel core catcher cooling system of an EU-APR1400, and these effects on the natural circulation flow rate are analyzed and compared with the minimum flow rate required for the safe operation of the system. (authors)

  9. Requalification of the 235-F Metallograph Facility gloveboxes for use in the 773-A plutonium immobilization demonstration

    SciTech Connect

    Hinds, S.S; Hidlay, J.

    1997-10-16

    A concern has been identified regarding the viability of redesigning and requalifying existing glovebox lines for use as glovebox lines integral to future mission activities in the 773-A laboratory building at the Savannah River Site (SRS). The Bechtel Savannah River Inc. (BSRI) design engineering team has been requested to perform an evaluation which would investigate the reuse of these existing gloveboxes versus the procurement of completely new glovebox systems. The existing glovebox lines were manufactured for the Plutonium (Pu) Metallograph Facility, Project 3253, located in building 235-F at SRS. These gloveboxes were designed as independent, fully functional Pu `metal` and Pu `oxide` processing glovebox systems for this facility. These gloveboxes, although fully installed, have never processed radioactive material. The proposed use for these gloveboxes are: (1) to utilize the Pu `metal` glovebox system for the primary containment associated with the Pre-Processing/Re-Processing Laboratory for obtaining radioactive glass compound viscometer analysis and (2) to utilize the Pu `oxide` glovebox system for primary containment associated with the Pu `Can in Can` Demonstration for proof of principle testing specific to long term Pu immobilization and storage technology. This report presents objective evidence that supports the engineering judgment indicating the existing gloveboxes can be requalified for the proposed uses indicated above. SRS has the ability to duplicate the test parameters, with site forces, that will meet or exceed the identical acceptance criteria established to qualify the existing gloveboxes. The qualification effort will be a documented procedure using the leak test criteria characteristic of the original glovebox purchase. Two equivalent tests will be performed, one for post modification leak test acceptance and one for post installation leak test acceptance. (Abstract Truncated).

  10. Cooling Vest

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Because quadriplegics are unable to perspire below the level of spinal injury, they cannot tolerate heat stress. A cooling vest developed by Ames Research Center and Upjohn Company allows them to participate in outdoor activities. The vest is an adaptation of Ames technology for thermal control garments used to remove excess body heat of astronauts. The vest consists of a series of corrugated channels through which cooled water circulates. Its two outer layers are urethane coated nylon, and there is an inner layer which incorporates the corrugated channels. It can be worn as a backpack or affixed to a wheelchair. The unit includes a rechargeable battery, mini-pump, two quart reservoir and heat sink to cool the water.

  11. Cooled railplug

    DOEpatents

    Weldon, W.F.

    1996-05-07

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers. 10 figs.

  12. Group IVA irons: New constraints on the crystallization and cooling history of an asteroidal core with a complex history

    NASA Astrophysics Data System (ADS)

    McCoy, T. J.; Walker, R. J.; Goldstein, J. I.; Yang, J.; McDonough, W. F.; Rumble, D.; Chabot, N. L.; Ash, R. D.; Corrigan, C. M.; Michael, J. R.; Kotula, P. G.

    2011-11-01

    , consistent with an oxidized parent body. The depletions in Ga may reflect decreased siderophilic behavior in a relatively oxidized body, and more favorable partitioning into the silicate portion of the parent body. Phosphate inclusions in EET show Δ 17O values within the range measured for silicates in IVA iron meteorites. EET has a typical ataxitic microstructure with precipitates of kamacite within a matrix of plessite. Chemical and isotopic evidence for a genetic relation between EET and group IVA is strong, but the high Ni content and the newly determined, rapid cooling rate of this meteorite show that it should continue to be classified as ungrouped. Previously reported metallographic cooling rates for IVA iron meteorites have been interpreted to indicate an inwardly crystallizing, ˜150 km radius metallic body with little or no silicate mantle. Hence, the IVA group was likely formed as a mass of molten metal separated from a much larger parent body that was broken apart by a large impact. Given the apparent genetic relation with IVA, EET was most likely generated via crystal-liquid fractionation in another, smaller body spawned from the same initial liquid during the impact event that generated the IVA body.

  13. Cooling of neutron stars

    NASA Technical Reports Server (NTRS)

    Pethick, C. J.

    1992-01-01

    It is at present impossible to predict the interior constitution of neutron stars based on theory and results from laboratory studies. It has been proposed that it is possible to obtain information on neutron star interiors by studying thermal radiation from their surfaces, because neutrino emission rates, and hence the temperature of the central part of a neutron star, depend on the properties of dense matter. The theory predicts that neutron stars cool relatively slowly if their cores are made up of nucleons, and cool faster if the matter is in an exotic state, such as a pion condensate, a kaon condensate, or quark matter. This view has recently been questioned by the discovery of a number of other processes that could lead to copious neutrino emission and rapid cooling.

  14. Cool Sportswear

    NASA Technical Reports Server (NTRS)

    1982-01-01

    New athletic wear design based on the circulating liquid cooling system used in the astronaut's space suits, allows athletes to perform more strenuous activity without becoming overheated. Techni-Clothes gear incorporates packets containing a heat-absorbing gel that slips into an insulated pocket of the athletic garment and is positioned near parts of the body where heat transfer is most efficient. A gel packet is good for about one hour. Easily replaced from a supply of spares in an insulated container worn on the belt. The products, targeted primarily for runners and joggers and any other athlete whose performance may be affected by hot weather, include cooling headbands, wrist bands and running shorts with gel-pack pockets.

  15. Global cooling?

    PubMed

    Damon, P E; Kunen, S M

    1976-08-01

    The world's inhabitants, including Scientists, live primarily in the Northern Hemisphere. It is quite natural to be concerned about events that occur close to home and neglect faraway events. Hence, it is not surprising that so little attention has been given to the Southern Hemisphere. Evidence for global cooling has been based, in large part, on a severe cooling trend at high northern latitudes. This article points out that the Northern Hemisphere cooling trend appears to be out of phase with a warming trend at high latitudes in the Southern Hemisphere. The data are scanty. We cannot be sure that these temperature fluctuations are be not the result of natural causes. How it seems most likely that human activity has already significantly perturbed the atmospheric weather system. The effect of particulate matter pollution should be most severe in the highly populated and industrialized Northern Hemisphere. Because of the rapid diffusion of CO(2) molecules within the atmosphere, both hemispheres will be subject to warming due to the atmospheric (greenhouse) effect as the CO(2) content of the atmosphere builds up from the combustion of fossil fuels. Because of the differential effects of the two major sources of atmospheric pollution, the CO(2) greenhouse effect warming trend should first become evident in the Southern Hemisphere. The socioeconomic and political consequences of climate change are profound. We need an early warning system such as would be provided by a more intensive international world weather watch, particularly at high northern and southern latitudes.

  16. SIMULATING THE COOLING FLOW OF COOL-CORE CLUSTERS

    SciTech Connect

    Li Yuan; Bryan, Greg L.

    2012-03-01

    We carry out high-resolution adaptive mesh refinement simulations of a cool core cluster, resolving the flow from Mpc scales down to pc scales. We do not (yet) include any active galactic nucleus (AGN) heating, focusing instead on cooling in order to understand how gas reaches the supermassive black hole at the center of the cluster. We find that, as the gas cools, the cluster develops a very flat temperature profile, undergoing a cooling catastrophe only in the central 10-100 pc of the cluster. Outside of this region, the flow is smooth, with no local cooling instabilities, and naturally produces very little low-temperature gas (below a few keV), in agreement with observations. The gas cooling in the center of the cluster rapidly forms a thin accretion disk. The amount of cold gas produced at the very center grows rapidly until a reasonable estimate of the resulting AGN heating rate (assuming even a moderate accretion efficiency) would overwhelm cooling. We argue that this naturally produces a thermostat which links the cooling of gas out to 100 kpc with the cold gas accretion in the central 100 pc, potentially closing the loop between cooling and heating. Isotropic heat conduction does not affect the result significantly, but we show that including the potential well of the brightest cluster galaxy is necessary to obtain the correct result. Also, we found that the outcome is sensitive to resolution, requiring very high mass resolution to correctly reproduce the small transition radius.

  17. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  18. THE ROLE OF AQUEOUS THIN FILM EVAPORATIVE COOLING ON RATES OF ELEMENTAL MERCURY AIR-WATER EXCHANGE UNDER TEMPERATURE DISEQUILIBRIUM CONDITIONS

    EPA Science Inventory

    The technical conununity has only recently addressed the role of atmospheric temperature variations on rates of air-water vapor phase toxicant exchange. The technical literature has documented that: 1) day time rates of elemental mercury vapor phase air-water exchange can exceed ...

  19. Control Algorithms For Liquid-Cooled Garments

    NASA Technical Reports Server (NTRS)

    Drew, B.; Harner, K.; Hodgson, E.; Homa, J.; Jennings, D.; Yanosy, J.

    1988-01-01

    Three algorithms developed for control of cooling in protective garments. Metabolic rate inferred from temperatures of cooling liquid outlet and inlet, suitably filtered to account for thermal lag of human body. Temperature at inlet adjusted to value giving maximum comfort at inferred metabolic rate. Applicable to space suits, used for automatic control of cooling in suits worn by workers in radioactive, polluted, or otherwise hazardous environments. More effective than manual control, subject to frequent, overcompensated adjustments as level of activity varies.

  20. Effect of cooling rate on the survival of cryopreserved rooster sperm: Comparison of different distances in the vapor above the surface of the liquid nitrogen.

    PubMed

    Madeddu, M; Mosca, F; Abdel Sayed, A; Zaniboni, L; Mangiagalli, M G; Colombo, E; Cerolini, S

    2016-08-01

    The aim of the present trial was to study the effect of different freezing rates on the survival of cryopreserved rooster semen packaged in straws. Slow and fast freezing rates were obtained keeping straws at different distances in the vapor above the surface of the nitrogen during freezing. Adult Lohmann roosters (n=27) were used. Two experiments were conducted. In Experiment 1, semen was packaged in straws and frozen comparing the distances of 1, 3 and 5cm in nitrogen vapor above the surface of the liquid nitrogen. In Experiment 2, the distances of 3, 7 and 10cm above the surfaces of the liquid nitrogen were compared. Sperm viability, motility and progressive motility and the kinetic variables were assessed in fresh and cryopreserved semen samples. The recovery rates after freezing/thawing were also calculated. In Experiment 1, there were no significant differences among treatments for all semen quality variables. In Experiment 2, the percentage of viable (46%) and motile (22%) sperm in cryopreserved semen was greater when semen was placed 3cm compared with 7 and 10cm in the vapor above the surface of the liquid nitrogen. The recovery rate of progressive motile sperm after thawing was also greater when semen was stored 3cm in the vapor above the surface of the liquid nitrogen. More rapid freezing rates are required to improve the survival of rooster sperm after cryopreservation and a range of distances from 1 to 5cm in nitrogen vapor above the surface of the liquid nitrogen is recommended for optimal sperm viability. PMID:27349144

  1. Restaurant food cooling practices.

    PubMed

    Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

    2012-12-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study.

  2. Cab Heating and Cooling

    SciTech Connect

    Damman, Dennis

    2005-10-31

    Schneider National, Inc., SNI, has concluded the Cab Heating and Cooling evaluation of onboard, engine off idling solutions. During the evaluation period three technologies were tested, a Webasto Airtronic diesel fired heater for cold weather operation, and two different approaches to cab cooling in warm weather, a Webasto Parking Cooler, phase change storage system and a Bergstrom Nite System, a 12 volt electrical air conditioning approach to cooling. Diesel fired cab heaters were concluded to provide adequate heat in winter environments down to 10 F. With a targeted idle reduction of 17%, the payback period is under 2 years. The Webasto Parking Cooler demonstrated the viability of this type of technology, but required significant driver involvement to achieve maximum performance. Drivers rated the technology as ''acceptable'', however, in individual discussions it became apparent they were not satisfied with the system limitations in hot weather, (over 85 F). The Bergstrom Nite system was recognized as an improvement by drivers and required less direct driver input to operate. While slightly improved over the Parking Cooler, the hot temperature limitations were only slightly better. Neither the Parking Cooler or the Nite System showed any payback potential at the targeted 17% idle reduction. Fleets who are starting at a higher idle baseline may have a more favorable payback.

  3. Debuncher Cooling Limitations to Stacking

    SciTech Connect

    Halling, Mike

    1991-08-13

    During the January studies period we performed studies to determine the effect that debuncher cooling has on the stacking rate. Two different sets of measurements were made separated by about a week. Most measurements reported here are in PBAR log 16, page 243-247. These measurements were made by changing the accelerator timeline to give about 6 seconds between 29's, and then gating the cooling systems to simulate reduced cycle times. For the measurement of the momentum cooling effectiveness the gating switches could not be made to work, so the timeline was changed for each measurement. The cooling power of all three systems was about 800 watts for the tests reported here. We now regularly run at 1200 watts per system.

  4. Photoacoustic study of the influence of the cooling temperature on the CO2 emission rate by Carica papaya L. in modified atmosphere

    NASA Astrophysics Data System (ADS)

    Schramm, D. U.; Sthel, M. S.; da Silva, M. G.; Carneiro, L. O.; Silva, H. R. F.; Martins, M. L. L.; Resende, E. D.; Vitorazi, L.; Vargas, H.

    2005-06-01

    The monitoring of trace gas emitted by papaya fruits and assessments of its mass loss can contribute to improve the conditions for their storage and transport. The C02 emission rate by the papaya fruits, monitored by a commercial infrared-based gas analyzer, was influenced by the temperature and storage time. The fruits stored at temperature of 13 °C accumulated more CO2 inside the PEBD bags than those fruits stored at 6 °C. The loss of mass of the fruits progressively increased with storage time for both temperatures until the saturation of the moisture inside the PEBD bag, been more pronounced at 13 ºC.

  5. Electron impact cross-sections and cooling rates for methane. [in thermal balance of electrons in atmospheres and ionospheres of planets and satellites in outer solar system

    NASA Technical Reports Server (NTRS)

    Gan, L.; Cravens, T. E.

    1992-01-01

    Energy transfer between electrons and methane gas by collisional processes plays an important role in the thermal balance of electrons in the atmospheres and ionospheres of planets and satellites in the outer solar system. The literature is reviewed for electron impact cross-sections for methane in this paper. Energy transfer rates are calculated for elastic and inelastic processes using a Maxwellian electron distribution. Vibrational, rotational, and electronic excitation and ionization are included. Results are presented for a wide range of electron temperatures and neutral temperatures.

  6. A study of 239Pu production rate in a water cooled natural uranium blanket mock-up of a fusion-fission hybrid reactor

    NASA Astrophysics Data System (ADS)

    Feng, Song; Liu, Rong; Lu, Xinxin; Yang, Yiwei; Xu, Kun; Wang, Mei; Zhu, Tonghua; Jiang, Li; Qin, Jianguo; Jiang, Jieqiong; Han, Zijie; Lai, Caifeng; Wen, Zhongwei

    2016-03-01

    The 239Pu production rate is important data in neutronics design for a natural uranium blanket of a fusion-fission hybrid reactor, and the accuracy and reliability should be validated by integral experiments. The distribution of 239Pu production rates in a subcritical natural uranium blanket mock-up was obtained for the first time with a D-T neutron generator by using an activation technique. Natural uranium foils were placed in different spatial locations of the mock-up, the counts of 277.6 keV γ-rays emitted from 239Np generated by 238U capture reaction were measured by an HPGe γ spectrometer, and the self-absorption of natural uranium foils was corrected. The experiment was analyzed using the Super Monte Carlo neutron transport code SuperMC2.0 with recent nuclear data of 238U from the ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0u2, JEFF-3.2 and CENDL-3.1 libraries. Calculation results with the JEFF-3.2 library agree with the experimental ones best, and they agree within the experimental uncertainty in general with the average ratios of calculation results to experimental results (C/E) in the range of 0.93 to 1.01.

  7. Peltier cooling of fermionic quantum gases.

    PubMed

    Grenier, Ch; Georges, A; Kollath, C

    2014-11-14

    We propose a cooling scheme for fermionic quantum gases, based on the principles of the Peltier thermoelectric effect and energy filtering. The system to be cooled is connected to another harmonically trapped gas acting as a reservoir. The cooling is achieved by two simultaneous processes: (i) the system is evaporatively cooled, and (ii) cold fermions from deep below the Fermi surface of the reservoir are injected below the Fermi level of the system, in order to fill the "holes" in the energy distribution. This is achieved by a suitable energy dependence of the transmission coefficient connecting the system to the reservoir. The two processes can be viewed as simultaneous evaporative cooling of particles and holes. We show that both a significantly lower entropy per particle and faster cooling rate can be achieved in this way than by using only evaporative cooling. PMID:25432033

  8. Hybrid radiator cooling system

    DOEpatents

    France, David M.; Smith, David S.; Yu, Wenhua; Routbort, Jules L.

    2016-03-15

    A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.

  9. Thermotechnical performance of an air-cooled tuyere with air cooling channels in series

    NASA Astrophysics Data System (ADS)

    Shen, Yuansheng; Zhou, Yuanyuan; Zhu, Tao; Duan, Guangbin

    2016-03-01

    To reduce the cooling air consumption for an air-cooled tuyere, an air-cooled tuyere with air cooling channels in series is developed based on several hypotheses, i.e., a transparent medium in the blast furnace, among others, and the related mathematical models are introduced and developed. Referring to the data from a BF site, the thermotechnical computation for the air-cooled tuyere was performed, and the results show that when the temperature of the inlet cooling air increases, the temperatures for the outlet cooling air, the outer surface of the tuyere, the walls of the air cooling channels and the center channel as well as the heat going into the center channel increase, but the heat absorbed by the cooling air flowing through the air cooling channels decreases. When the cooling air flow rate under the standard state increases, the physical parameters mentioned above change in an opposite directions. Compared to a water-cooled tuyere, the energy savings for an air-cooled tuyere are more than 0.23 kg/min standard coal.

  10. Restaurant food cooling practices.

    PubMed

    Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

    2012-12-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study. PMID:23212014

  11. Mineralogy and cooling history of magnesian lunar granulite 67415

    NASA Technical Reports Server (NTRS)

    Takeda, Hiroshi; Miyamoto, Masamichi

    1993-01-01

    Apollo granulite 67415 was investigated by mineralogical techniques to gain better understanding of cooling histories of lunar granulities. Cooling rates were estimated from chemical zoning of olivines in magnesian granulitic clasts by computer simulation of diffusion processes. The cooling rate of 10 deg C/yr obtained is compatible with a model of the granulite formation, in which the impact deposit was cooled from high temperature or annealed, at the depth of about 25 m beneath the surface.

  12. Full coverage discrete hole film cooling - Cooling effectiveness

    NASA Astrophysics Data System (ADS)

    Andrews, G. E.; Gupta, M. L.; Mkpadi, M. C.

    1985-09-01

    The development of a test facility for investigating full coverage discrete hole wall cooling for gas turbine combustion chamber wall cooling is described. A low temperature test condition of 750 K mainstream temperature and 300 K coolant temperature was used to investigate the influence of coolant flow rate at a constant cross flow Mach number. Practical combustion conditions of 2100 K combustor temperature and 700 K coolant temperature are investigated to establish the validity of applying the low temperature results to practical conditions. For both situations a heat balance program taking into account the heat transfer within the wall, was used to compute the film heat transfer coefficients. The mixing of the coolant air with the mainstream gases was studied through boundary layer temperature and CO2 profiles. It is shown that entrainment of hot flame gases between the injection holes results in a very low 'adiabatic' film cooling effectiveness.

  13. Some metallographic results for brush bristles and brush segments of a shroud ring brush seal tested in a T-700 engine

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George A.; Bill, Robert C.; Hull, David R.; Csavina, Kristine R.

    1994-01-01

    Post-test investigation of a T-700 engine brush seal found regions void of bristles ('yanked out'), regions of bent-over bristles near the inlet, some 'snapped' bristles near the fence, and a more uniform smeared bristle interface between the first and last axial rows of bristles. Several bristles and four brush segments were cut from the brush seal, wax mounted, polished, and analyzed. Metallographic analysis of the bristle near the rub tip showed tungsten-rich phases uniformly distributed throughout the bristle, no apparent change within 1 mu m of the interface, and possibly a small amount of titanium, which would represent a transfer from the rotor. Analysis of the bristle wear face showed nonuniform tungsten, which is indicative of material resolidification. The cut end contained oxides and internal fractures; the worn end was covered with oxide scale. Material losses due to wear and elastoplastic deformation within the shear zone and third-body lubrication effects in the contact zone are discussed.

  14. Some metallographic results for brush bristles and brush segments of a shroud ring brush seal tested in a T-700 engine

    NASA Astrophysics Data System (ADS)

    Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George A.; Bill, Robert C.; Hull, David R.; Csavina, Kristine R.

    1994-07-01

    Post-test investigation of a T-700 engine brush seal found regions void of bristles ('yanked out'), regions of bent-over bristles near the inlet, some 'snapped' bristles near the fence, and a more uniform smeared bristle interface between the first and last axial rows of bristles. Several bristles and four brush segments were cut from the brush seal, wax mounted, polished, and analyzed. Metallographic analysis of the bristle near the rub tip showed tungsten-rich phases uniformly distributed throughout the bristle, no apparent change within 1 mu m of the interface, and possibly a small amount of titanium, which would represent a transfer from the rotor. Analysis of the bristle wear face showed nonuniform tungsten, which is indicative of material resolidification. The cut end contained oxides and internal fractures; the worn end was covered with oxide scale. Material losses due to wear and elastoplastic deformation within the shear zone and third-body lubrication effects in the contact zone are discussed.

  15. Liquid-Cooled Garment

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A liquid-cooled bra, offshoot of Apollo moon suit technology, aids the cancer-detection technique known as infrared thermography. Water flowing through tubes in the bra cools the skin surface to improve resolution of thermograph image.

  16. Liquid cooled garments

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Liquid cooled garments employed in several applications in which severe heat is encountered are discussed. In particular, the use of the garments to replace air line cooling units in a variety of industrial processing situations is discussed.

  17. Heat pipe cooled power magnetics

    NASA Technical Reports Server (NTRS)

    Chester, M. S.

    1979-01-01

    A high frequency, high power, low specific weight (0.57 kg/kW) transformer developed for space use was redesigned with heat pipe cooling allowing both a reduction in weight and a lower internal temperature rise. The specific weight of the heat pipe cooled transformer was reduced to 0.4 kg/kW and the highest winding temperature rise was reduced from 40 C to 20 C in spite of 10 watts additional loss. The design loss/weight tradeoff was 18 W/kg. Additionally, allowing the same 40 C winding temperature rise as in the original design, the KVA rating is increased to 4.2 KVA, demonstrating a specific weight of 0.28 kg/kW with the internal loss increased by 50W. This space environment tested heat pipe cooled design performed as well electrically as the original conventional design, thus demonstrating the advantages of heat pipes integrated into a high power, high voltage magnetic. Another heat pipe cooled magnetic, a 3.7 kW, 20A input filter inductor was designed, developed, built, tested, and described. The heat pipe cooled magnetics are designed to be Earth operated in any orientation.

  18. Radial turbine cooling

    NASA Astrophysics Data System (ADS)

    Roelke, Richard J.

    The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

  19. Radial turbine cooling

    NASA Technical Reports Server (NTRS)

    Roelke, Richard J.

    1992-01-01

    The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

  20. Data center cooling system

    DOEpatents

    Chainer, Timothy J; Dang, Hien P; Parida, Pritish R; Schultz, Mark D; Sharma, Arun

    2015-03-17

    A data center cooling system may include heat transfer equipment to cool a liquid coolant without vapor compression refrigeration, and the liquid coolant is used on a liquid cooled information technology equipment rack housed in the data center. The system may also include a controller-apparatus to regulate the liquid coolant flow to the liquid cooled information technology equipment rack through a range of liquid coolant flow values based upon information technology equipment temperature thresholds.

  1. Optimation of cooled shields in insulations

    NASA Technical Reports Server (NTRS)

    Chato, J. C.; Khodadadi, J. M.; Seyed-Yagoobi, J.

    1984-01-01

    A method to optimize the location, temperature, and heat dissipation rate of each cooled shield inside an insulation layer was developed. The method is based on the minimization of the entropy production rate which is proportional to the heat leak across the insulation. It is shown that the maximum number of shields to be used in most practical applications is three. However, cooled shields are useful only at low values of the overall, cold wall to hot wall absolute temperature ratio. The performance of the insulation system is relatively insensitive to deviations from the optimum values of the temperature and location of the cooling shields. Design curves for rapid estimates of the locations and temperatures of cooling shields in various types of insulations, and an equation for calculating the cooling loads for the shields are presented.

  2. Cool flame quench distances

    NASA Technical Reports Server (NTRS)

    Ryason, P. R.; Hirsch, E.

    1974-01-01

    The results of a brief experimental investigation are presented which confirm the expectation that cool flame quenching distances should be larger than hot flame quenching distances. It is also discovered that whereas quenching distances for hot flames reach their minimum values near stoichiometric conditions, cool flame quenching distances are least under rich conditions. Rich conditions are well known to favor cool flame formation.

  3. Cooling of stored beams

    SciTech Connect

    Mills, F.E.

    1986-10-15

    Beam cooling methods developed for the accumulation of antiprotons are being employed to assist in the performance of experiments in Nuclear and Particle Physics with ion beams stored in storage rings. The physics of beam cooling, and the ranges of utility of stochastic and electron cooling are discussed in this paper.

  4. Stochastic cooling in RHIC

    SciTech Connect

    Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

    2009-05-04

    After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

  5. Cooling water distribution system

    DOEpatents

    Orr, Richard

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

  6. Heating and cooling system

    SciTech Connect

    Imig, L.A.; Gardner, M.R.

    1982-08-01

    A heating and cooling apparatus capable of cyclic heating and cooling of a test specimen undergoing fatigue testing is discussed. Cryogenic fluid is passed through a block clamped to the speciment to cool the block and the specimen. Heating cartridges penetrate the block to heat the block and the specimen to very hot temperaures. Control apparatus is provided to alternatively activate the cooling and heating modes to effect cyclic heating and cooling between very hot and very cold temperatures. The block is constructed of minimal mass to facilitate the rapid temperature changes. Official Gazette of the U.S. Patent and Trademark Office.

  7. Passive Cooling of Body Armor

    NASA Astrophysics Data System (ADS)

    Holtz, Ronald; Matic, Peter; Mott, David

    2013-03-01

    Warfighter performance can be adversely affected by heat load and weight of equipment. Current tactical vest designs are good insulators and lack ventilation, thus do not provide effective management of metabolic heat generated. NRL has undertaken a systematic study of tactical vest thermal management, leading to physics-based strategies that provide improved cooling without undesirable consequences such as added weight, added electrical power requirements, or compromised protection. The approach is based on evaporative cooling of sweat produced by the wearer of the vest, in an air flow provided by ambient wind or ambulatory motion of the wearer. Using an approach including thermodynamic analysis, computational fluid dynamics modeling, air flow measurements of model ventilated vest architectures, and studies of the influence of fabric aerodynamic drag characteristics, materials and geometry were identified that optimize passive cooling of tactical vests. Specific architectural features of the vest design allow for optimal ventilation patterns, and selection of fabrics for vest construction optimize evaporation rates while reducing air flow resistance. Cooling rates consistent with the theoretical and modeling predictions were verified experimentally for 3D mockups.

  8. Inductive cooling in quantum magnetomechanics

    NASA Astrophysics Data System (ADS)

    Romero-Sanchez, Erick; Twamley, Jason; Bowen, Warwick P.; Vanner, Michael R.

    Coupling to light or microwave fields allows quantum control of the motion of a mechanical oscillator, and offers prospects for precision sensing, quantum information systems, and tests of fundamental physics. In cavity electromechanics ground state cooling has been achieved using resolved sideband cooling. Here we present an alternative approach based on a magnetomechanical system that inductively couples an LC resonator to a mechanical oscillator. The experimental setup consists of a micro cantilever with a pyramidal magnetic tip attached at the end of the beam. The sharp end of the magnetic tip is positioned close to the planar microfabricated inductor of the LC resonator. The displacement in the position of the end of the cantilever generates a change in flux through the coil inducing an electromotive force in the circuit. The current in the LC resonator generates a magnetic field, and then a force between the tip and the coil. When they are strongly coupled and the mechanical resonance frequency ωm exceeds the electrical decay rate of the resonator γe, resolved sideband cooling can be used to cool the mechanics. We present estimations for the coupling rates and the experimental parameters required for these experiments. E. Romero acknowledges to CONACyT.

  9. Thermal crack damage is dominated by cooling

    NASA Astrophysics Data System (ADS)

    Browning, John; Meredith, Philip; Gudmundsson, Agust

    2016-04-01

    Most studies of thermally-induced cracking to date have focused on the generation of cracks formed during heating and thermal expansion. Both the nature and mechanism of crack formation during cooling are hypothesised to be different from those formed during heating. We present in-situ acoustic emission data recorded as a proxy for crack damage evolution throughout a series of heating and cooling experiments on samples of basalt and dacite. The results show that both the rate and energy of acoustic emission are consistently much higher during cooling than during heating. When comparing the AE during the heating phase with the AE during the cooling phase of a comparable duration heating and cooling cycle; we find that there are ~ 150 times as many hits during cooling. Furthermore, the average energy of those AE are more than 3 times greater, resulting in a total AE energy that is almost 500 times higher during cooling than during heating. Seismic velocity comparisons and crack morphology analysis of our heated and cooled samples support the contemporaneous acoustic emission data and also indicate that thermal cracking is largely isotropic. These new data are important for assessing the contribution of cooling-induced damage within volcanic structures and layers such as dikes, sills and lava flows.

  10. The Cool Flames Experiment

    NASA Technical Reports Server (NTRS)

    Pearlman, Howard; Chapek, Richard; Neville, Donna; Sheredy, William; Wu, Ming-Shin; Tornabene, Robert

    2001-01-01

    A space-based experiment is currently under development to study diffusion-controlled, gas-phase, low temperature oxidation reactions, cool flames and auto-ignition in an unstirred, static reactor. At Earth's gravity (1g), natural convection due to self-heating during the course of slow reaction dominates diffusive transport and produces spatio-temporal variations in the thermal and thus species concentration profiles via the Arrhenius temperature dependence of the reaction rates. Natural convection is important in all terrestrial cool flame and auto-ignition studies, except for select low pressure, highly dilute (small temperature excess) studies in small vessels (i.e., small Rayleigh number). On Earth, natural convection occurs when the Rayleigh number (Ra) exceeds a critical value of approximately 600. Typical values of the Ra, associated with cool flames and auto-ignitions, range from 104-105 (or larger), a regime where both natural convection and conduction heat transport are important. When natural convection occurs, it alters the temperature, hydrodynamic, and species concentration fields, thus generating a multi-dimensional field that is extremely difficult, if not impossible, to be modeled analytically. This point has been emphasized recently by Kagan and co-workers who have shown that explosion limits can shift depending on the characteristic length scale associated with the natural convection. Moreover, natural convection in unstirred reactors is never "sufficiently strong to generate a spatially uniform temperature distribution throughout the reacting gas." Thus, an unstirred, nonisothermal reaction on Earth does not reduce to that generated in a mechanically, well-stirred system. Interestingly, however, thermal ignition theories and thermokinetic models neglect natural convection and assume a heat transfer correlation of the form: q=h(S/V)(T(bar) - Tw) where q is the heat loss per unit volume, h is the heat transfer coefficient, S/V is the surface to

  11. A metallographic study of porosity and fracture behavior in relation to the tensile properties in 319.2 end chill castings

    SciTech Connect

    Samuel, A.M.; Samuel, F.H.

    1995-09-01

    A metallographic study of the porosity and fracture behavior in unidirectionally solidified end chill castings of 319.2 aluminum alloy (Al-6.2 pct Si-3.8 pct Cu-0.5 pct Fe-0.14 pct Mn-0.06 pct Mg-0.073 pct Ti) was carried out using optical microscopy and scanning electron microscopy (SEM) to determine their relationship with the tensile properties. The parameters varied in the production of these castings were the hydrogen ({approximately}0.1 and {approximately}0.37 mL/100 g Al), modifier (0 and 300 ppm Sr), and grain refiner (0 and 0.03 wt pct Ti) concentrations, as well as the solidification time, which increased with decreasing distance from the end chill bottom of the casting, giving dendrite arm spacings (DASs) ranging from {approximately}15 to {approximately}95 {micro}m. Image analysis and energy dispersive X-ray (EDX) analysis were employed for quantification of porosity/microstructural constituents and fracture surface analysis (phase identification), respectively. The results showed that the local solidification time (viz. DAS) significantly influences the ductility at low hydrogen levels; at higher levels, however, hydrogen has a more pronounced effect (porosity related) on the drop in ductility. Porosity is mainly observed in the form of elongated pores along the grain boundaries, with Sr increasing the porosity volume percent and grain refining increasing the probability for pore branching. The beneficial effect of Sr modification, however, improves the alloy ductility. Fracture of the Si, {beta}-Al{sub 5}FeSi, {alpha}-Al{sub 15}(Fe,Mn){sub 3}Si{sub 2}, and Al{sub 2}Cu phases takes place within the phase particles rather than at the particle/Al matrix interface. Sensitivity of tensile properties to DAS allows for the use of the latter as an indicator of the expected properties of the alloy.

  12. On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces.

    PubMed

    Yin, Siaw Hui; Kuppuswamy, R

    2009-01-10

    Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces, has been practised quite successfully in forensic science laboratories all over the world. A large number of etchants suitable for particular metal surfaces based on empirical studies is available in the literature. This article reviews the sensitivity and efficacy of some popular etchants for recovering obliterated marks on medium carbon steel (0.31% C with ferrite-pearlite microstructure) used in automobile parts. The experiments involved engraving these carbon steel plates with some alphanumeric characters using a computer controlled machine "Gravograph" and erasing them to several depths below the bottom of their engraving depth. Seven metallographic reagents of which most of them were copper containing compounds were chosen for etching. The erased plates were etched with every one of these etchants using swabbing method. The results have revealed that Fry's reagent comprising cupric chloride 90 g, hydrochloric acid 120 mL and water 100mL provided the necessary contrast and was concluded to be the most sensitive. The same reagent was recommended by earlier workers for revealing strain lines in steel surfaces. Earlier, another reagent containing 5 g copper sulphate, 60 mL water, 30 mL (conc.) ammonium hydroxide, and 60 mL (conc.) hydrochloric acid was proved to be more sensitive to restore erased marks on low carbon steel (0.1% C with ferrite-pearlite structure) [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32]. Thus the sensitivity of the etching reagent on steel surfaces appeared to be dependent on the content of carbon in the steel. PMID:19041202

  13. Plugging of cooling holes in film-cooled turbine vanes

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Lowell, C. E.

    1977-01-01

    The plugging of vane cooling holes by impurities in a marine gas turbine was closely simulated in burner rig tests where dopants were added to the combustion products of a clean fuel (Jet-A). Hole plugging occurred when liquid phases, resulting from the dopants, were present in the combustion products. Increasing flame temperature and dopant concentration resulted in an increased rate of deposition and hole plugging.

  14. Transphase cool storage test report

    SciTech Connect

    Stovall, T.K.

    1993-12-01

    The Ice Storage Test Facility (ISTF) is designed to test commercial cool storage systems. Transphase, Inc. provided a prototype of a new storage tank design equipped with coils designed for use with a secondary fluid system and filled with a eutectic designed to freeze at 41{degree}F. The Transphase cool storage system was tested over a wide range of operating conditions. Measured system performance during charging showed the ability to freeze the tank with relatively constant brine temperatures over most of the charging cycle. During discharge cycles, the storage tank outlet temperature was governed mainly by the brine flow rate and the tank`s remaining charge. The discharge capacity was dependent upon both the selected discharge rate and maximum allowable tank outlet temperature. This prototype unit experienced several operational problems, not unexpected for the first full-size execution of a new design. Such prototype testing was one of EPRI`s primary goals in founding the ISTF.

  15. Ozone Treatment For Cooling Towers

    NASA Technical Reports Server (NTRS)

    Blackwelder, Rick; Baldwin, Leroy V.; Feeney, Ellen S.

    1990-01-01

    Report presents results of study of cooling tower in which water treated with ozone instead of usual chemical agents. Bacteria and scale reduced without pollution and at low cost. Operating and maintenance costs with treatment about 30 percent of those of treatment by other chemicals. Corrosion rates no greater than with other chemicals. Advantage of ozone, even though poisonous, quickly detected by smell in very low concentrations.

  16. Cooling of hot electrons in amorphous silicon

    SciTech Connect

    Vanderhaghen, R.; Hulin, D.; Cuzeau, S.; White, J.O.

    1997-07-01

    Measurements of the cooling rate of hot carriers in amorphous silicon are made with a two-pump, one-probe technique. The experiment is simulated with a rate-equation model describing the energy transfer between a population of hot carriers and the lattice. An energy transfer rate proportional to the temperature difference is found to be consistent with the experimental data while an energy transfer independent of the temperature difference is not. This contrasts with the situation in crystalline silicon. The measured cooling rates are sufficient to explain the difficulty in observing avalanche effects in amorphous silicon.

  17. Gas turbine cooling system

    SciTech Connect

    Bancalari, Eduardo E.

    2001-01-01

    A gas turbine engine (10) having a closed-loop cooling circuit (39) for transferring heat from the hot turbine section (16) to the compressed air (24) produced by the compressor section (12). The closed-loop cooling system (39) includes a heat exchanger (40) disposed in the flow path of the compressed air (24) between the outlet of the compressor section (12) and the inlet of the combustor (14). A cooling fluid (50) may be driven by a pump (52) located outside of the engine casing (53) or a pump (54) mounted on the rotor shaft (17). The cooling circuit (39) may include an orifice (60) for causing the cooling fluid (50) to change from a liquid state to a gaseous state, thereby increasing the heat transfer capacity of the cooling circuit (39).

  18. Water cooled rolling grate incinerator

    SciTech Connect

    Ettehadieh, B.

    1991-08-27

    This patent describes a water cooled roller grate incinerator cooperatively associated with a boiler. It comprises cylindrical shaped roller grates, each having a plurality of circular arrays of spaced apart cooling tubes separated by perforated webs and connected at each end to a ring header; a rotary joint associated with each cylindrical roller grate for supplying cooling fluid to the circular array of tubes to keep them cool and returning heated fluid to the boiler; each roller grate being disposed to rotate about a centrally disposed axis; the axes of the roller grates being disposed in an inclined plane generally parallel to each other so as to form an undulating surface; a waster hopper with a waste feed ram disposed on the lower end of the hopper for feeding waste to the undulating surface; a combustion air system for supplying combustion air through the perforated webs to the waste pushed on the undulating surface by the waste feed ram to burn the waste; a separate drive system for each grate, the drive system regulating the rate at which the burning waste progresses across the undulating surface portion of each grate as the grates rotate transferring the waste from one roller grate to the next lower roller grate as the waste burns.

  19. Solar heating and cooling

    NASA Technical Reports Server (NTRS)

    Bartera, R. E.

    1978-01-01

    To emphasize energy conservation and low cost energy, the systems of solar heating and cooling are analyzed and compared with fossil fuel systems. The application of solar heating and cooling systems for industrial and domestic use are discussed. Topics of discussion include: solar collectors; space heating; pools and spas; domestic hot water; industrial heat less than 200 F; space cooling; industrial steam; and initial systems cost. A question and answer period is generated which closes out the discussion.

  20. The cooling of particle beams

    SciTech Connect

    Sessler, A.M.

    1994-10-01

    A review is given of the various methods which can be employed for cooling particle beams. These methods include radiation damping, stimulated radiation damping, ionization cooling, stochastic cooling, electron cooling, laser cooling, and laser cooling with beam coupling. Laser Cooling has provided beams of the lowest temperatures, namely 1 mK, but only for ions and only for the longitudinal temperature. Recent theoretical work has suggested how laser cooling, with the coupling of beam motion, can be used to reduce the ion beam temperature in all three directions. The majority of this paper is devoted to describing laser cooling and laser cooling with beam coupling.

  1. Semioptimal practicable algorithmic cooling

    NASA Astrophysics Data System (ADS)

    Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2011-04-01

    Algorithmic cooling (AC) of spins applies entropy manipulation algorithms in open spin systems in order to cool spins far beyond Shannon’s entropy bound. Algorithmic cooling of nuclear spins was demonstrated experimentally and may contribute to nuclear magnetic resonance spectroscopy. Several cooling algorithms were suggested in recent years, including practicable algorithmic cooling (PAC) and exhaustive AC. Practicable algorithms have simple implementations, yet their level of cooling is far from optimal; exhaustive algorithms, on the other hand, cool much better, and some even reach (asymptotically) an optimal level of cooling, but they are not practicable. We introduce here semioptimal practicable AC (SOPAC), wherein a few cycles (typically two to six) are performed at each recursive level. Two classes of SOPAC algorithms are proposed and analyzed. Both attain cooling levels significantly better than PAC and are much more efficient than the exhaustive algorithms. These algorithms are shown to bridge the gap between PAC and exhaustive AC. In addition, we calculated the number of spins required by SOPAC in order to purify qubits for quantum computation. As few as 12 and 7 spins are required (in an ideal scenario) to yield a mildly pure spin (60% polarized) from initial polarizations of 1% and 10%, respectively. In the latter case, about five more spins are sufficient to produce a highly pure spin (99.99% polarized), which could be relevant for fault-tolerant quantum computing.

  2. Passive containment cooling system

    DOEpatents

    Conway, Lawrence E.; Stewart, William A.

    1991-01-01

    A containment cooling system utilizes a naturally induced air flow and a gravity flow of water over the containment shell which encloses a reactor core to cool reactor core decay heat in two stages. When core decay heat is greatest, the water and air flow combine to provide adequate evaporative cooling as heat from within the containment is transferred to the water flowing over the same. The water is heated by heat transfer and then evaporated and removed by the air flow. After an initial period of about three to four days when core decay heat is greatest, air flow alone is sufficient to cool the containment.

  3. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  4. Body cooling after death.

    PubMed

    Kuehn, L A; Tikuisis, P; Livingstone, S; Limmer, R

    1980-09-01

    In the analyses of cases of death in cold air environments, it is often of interest to determine the time required for the body of the individual to cool to ambient temperature. Usually such determinations have been based on Newton's law of cooling. This paper describes a case history in which this technique was experimentally tested and consequently abandoned in favour of a more complex biophysical model which more accurately described the thermo-physical events inherent in body cooling. This model is recommended for determination of the times required for various body parts to cool to ambient environmental temperatures.

  5. Power electronics cooling apparatus

    SciTech Connect

    Sanger, Philip Albert; Lindberg, Frank A.; Garcen, Walter

    2000-01-01

    A semiconductor cooling arrangement wherein a semiconductor is affixed to a thermally and electrically conducting carrier such as by brazing. The coefficient of thermal expansion of the semiconductor and carrier are closely matched to one another so that during operation they will not be overstressed mechanically due to thermal cycling. Electrical connection is made to the semiconductor and carrier, and a porous metal heat exchanger is thermally connected to the carrier. The heat exchanger is positioned within an electrically insulating cooling assembly having cooling oil flowing therethrough. The arrangement is particularly well adapted for the cooling of high power switching elements in a power bridge.

  6. ELECTRON COOLING IN THE RECYCLER COOLER

    SciTech Connect

    SHEMYAKIN,A.; PROST, L.R.; FEDOTOV, A.; SIDORIN, A.

    2007-09-10

    A 0.1-0.5 A, 4.3 MeV DC electron beam provides cooling of 8 GeV antiprotons in Fermilab's Recycler storage ring. The most detailed information about the cooling properties of the electron beam comes from drag rate measurements. We find that the measured drag rate can significantly differ from the cooling force experienced by a single antiproton because the area of effective cooling is significantly smaller than the physical size of the electron beam and is comparable with the size of the antiproton beam used as a probe. Modeling by the BETACOOL code supports the conclusion about a large radial gradient of transverse velocities in the presently used electron beam.

  7. Evaporative cooling of antiprotons to cryogenic temperatures.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A; Hydomako, R; Jonsell, S; Kurchaninov, L; Lambo, R; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wilding, D; Wurtele, J S; Yamazaki, Y

    2010-07-01

    We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

  8. Evaporative Cooling of Antiprotons to Cryogenic Temperatures

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Wurtele, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A.; Madsen, N.; Werf, D. P. van der; Wilding, D.; Cesar, C. L.; Lambo, R.

    2010-07-02

    We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

  9. Effect of cooling condition on chemical vapor deposition synthesis of graphene on copper catalyst.

    PubMed

    Choi, Dong Soo; Kim, Keun Soo; Kim, Hyeongkeun; Kim, Yena; Kim, TaeYoung; Rhy, Se-hyun; Yang, Cheol-Min; Yoon, Dae Ho; Yang, Woo Seok

    2014-11-26

    Here, we show that chemical vapor deposition growth of graphene on copper foil is strongly affected by the cooling conditions. Variation of cooling conditions such as cooling rate and hydrocarbon concentration in the cooling step has yielded graphene islands with different sizes, density of nuclei, and growth rates. The nucleation site density on Cu substrate is greatly reduced when the fast cooling condition was applied, while continuing methane flow during the cooling step also influences the nucleation and growth rate. Raman spectra indicate that the graphene synthesized under fast cooling condition and methane flow on cool-down exhibit superior quality of graphene. Further studies suggest that careful control of the cooling rate and CH4 gas flow on the cooling step yield a high quality of graphene. PMID:25386721

  10. Liquid metal cooled nuclear reactors with passive cooling system

    DOEpatents

    Hunsbedt, Anstein; Fanning, Alan W.

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of cooling medium flow circuits which cooperate to remove and carry heat away from the fuel core upon loss of the normal cooling flow circuit to areas external thereto.

  11. Axion cooling of neutron stars

    NASA Astrophysics Data System (ADS)

    Sedrakian, Armen

    2016-03-01

    Cooling simulations of neutron stars and their comparison with the data from thermally emitting x-ray sources put constraints on the properties of axions, and by extension, of any light pseudoscalar dark matter particles, whose existence has been postulated to solve the strong-C P problem of QCD. We incorporate the axion emission by pair-breaking and formation processes by S - and P -wave nucleonic condensates in a benchmark code for cooling simulations, as well as provide fit formulas for the rates of these processes. Axion cooling of neutron stars has been simulated for 24 models covering the mass range 1 to 1.8 solar masses, featuring nonaccreted iron and accreted light-element envelopes, and a range of nucleon-axion couplings. The models are based on an equation state predicting conservative physics of superdense nuclear matter that does not allow for the onset of fast cooling processes induced by phase transitions to non-nucleonic forms of matter or high proton concentration. The cooling tracks in the temperature vs age plane were confronted with the (time-averaged) measured surface temperature of the central compact object in the Cas A supernova remnant as well as surface temperatures of three nearby middle-aged thermally emitting pulsars. We find that the axion coupling is limited to fa/107 GeV ≥(5 - 10 ) , which translates into an upper bound on axion mass ma≤(0.06 - 0.12 ) eV for Peccei-Quinn charges of the neutron |Cn|˜0.04 and proton |Cp|˜0.4 characteristic for hadronic models of axions.

  12. Elastocaloric cooling: Stretch to actively cool

    NASA Astrophysics Data System (ADS)

    Ossmer, Hinnerk; Kohl, Manfred

    2016-10-01

    The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

  13. District cooling in Scandinavia

    SciTech Connect

    Andersson, B.

    1996-11-01

    This paper will present the status of the development of district cooling systems in Scandinavia over the last 5 years. It will describe the technologies used in the systems that have been constructed as well as the options considered in different locations. It will identify the drivers for the development of the cooling business to-date, and what future drivers for a continuing development of district cooling in Sweden. To-date, approximately 25 different cities of varying sizes have completed feasibility studies to determine if district cooling is an attractive option. In a survey, that was conducted by the Swedish District Heating Association, some 25 cities expected to have district cooling systems in place by the year 2000. In Sweden, district heating systems with hot water is very common. In many cases, it is simply an addition to the current service for the district heating company to also supply district cooling to the building owners. A parallel from this can be drawn to North America where district cooling systems now are developing rapidly. I am convinced that in these cities a district heating service will be added as a natural expansion of the district cooling company`s service.

  14. Cool Earth Solar

    ScienceCinema

    Lamkin, Rob; McIlroy, Andy; Swalwell, Eric; Rajan, Kish

    2016-07-12

    In a public-private partnership that takes full advantage of the Livermore Valley Open Campus (LVOC) for the first time, Sandia National Laboratories and Cool Earth Solar have signed an agreement that could make solar energy more affordable and accessible. In this piece, representatives from Sandia, Cool Earth Solar, and leaders in California government all discuss the unique partnership and its expected impact.

  15. Data center cooling method

    DOEpatents

    Chainer, Timothy J.; Dang, Hien P.; Parida, Pritish R.; Schultz, Mark D.; Sharma, Arun

    2015-08-11

    A method aspect for removing heat from a data center may use liquid coolant cooled without vapor compression refrigeration on a liquid cooled information technology equipment rack. The method may also include regulating liquid coolant flow to the data center through a range of liquid coolant flow values with a controller-apparatus based upon information technology equipment temperature threshold of the data center.

  16. Measure Guideline: Ventilation Cooling

    SciTech Connect

    Springer, D.; Dakin, B.; German, A.

    2012-04-01

    The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  17. Cool Earth Solar

    SciTech Connect

    Lamkin, Rob; McIlroy, Andy; Swalwell, Eric; Rajan, Kish

    2013-04-22

    In a public-private partnership that takes full advantage of the Livermore Valley Open Campus (LVOC) for the first time, Sandia National Laboratories and Cool Earth Solar have signed an agreement that could make solar energy more affordable and accessible. In this piece, representatives from Sandia, Cool Earth Solar, and leaders in California government all discuss the unique partnership and its expected impact.

  18. S'COOL Science

    ERIC Educational Resources Information Center

    Bryson, Linda

    2004-01-01

    This article describes one fifth grade's participation in in NASA's S'COOL (Students' Cloud Observations On-Line) Project, making cloud observations, reporting them online, exploring weather concepts, and gleaning some of the things involved in authentic scientific research. S?COOL is part of a real scientific study of the effect of clouds on…

  19. Why Cool Roofs?

    ScienceCinema

    Chu, Steven

    2016-07-12

    By installing a cool roof at DOE, the federal government and Secretary Chu are helping to educate families and businesses about the important energy and cost savings that can come with this simple, low-cost technology. Cool roofs have the potential to quickly and dramatically reduce global carbon emissions while saving money every month on consumers' electrical bills.

  20. DOAS, Radiant Cooling Revisited

    SciTech Connect

    Hastbacka, Mildred; Dieckmann, John; Bouza, Antonio

    2012-12-01

    The article discusses dedicated outdoor air systems (DOAS) and radiant cooling technologies. Both of these topics were covered in previous ASHRAE Journal columns. This article reviews the technologies and their increasing acceptance. The two steps that ASHRAE is taking to disseminate DOAS information to the design community, available energy savings and the market potential of radiant cooling systems are addressed as well.

  1. Why Cool Roofs?

    SciTech Connect

    Chu, Steven

    2010-01-01

    By installing a cool roof at DOE, the federal government and Secretary Chu are helping to educate families and businesses about the important energy and cost savings that can come with this simple, low-cost technology. Cool roofs have the potential to quickly and dramatically reduce global carbon emissions while saving money every month on consumers' electrical bills.

  2. Air and water cooled modulator

    DOEpatents

    Birx, Daniel L.; Arnold, Phillip A.; Ball, Don G.; Cook, Edward G.

    1995-01-01

    A compact high power magnetic compression apparatus and method for delivering high voltage pulses of short duration at a high repetition rate and high peak power output which does not require the use of environmentally unacceptable fluids such as chlorofluorocarbons either as a dielectric or as a coolant, and which discharges very little waste heat into the surrounding air. A first magnetic switch has cooling channels formed therethrough to facilitate the removal of excess heat. The first magnetic switch is mounted on a printed circuit board. A pulse transformer comprised of a plurality of discrete electrically insulated and magnetically coupled units is also mounted on said printed board and is electrically coupled to the first magnetic switch. The pulse transformer also has cooling means attached thereto for removing heat from the pulse transformer. A second magnetic switch also having cooling means for removing excess heat is electrically coupled to the pulse transformer. Thus, the present invention is able to provide high voltage pulses of short duration at a high repetition rate and high peak power output without the use of environmentally unacceptable fluids and without discharging significant waste heat into the surrounding air.

  3. Air and water cooled modulator

    DOEpatents

    Birx, D.L.; Arnold, P.A.; Ball, D.G.; Cook, E.G.

    1995-09-05

    A compact high power magnetic compression apparatus and method are disclosed for delivering high voltage pulses of short duration at a high repetition rate and high peak power output which does not require the use of environmentally unacceptable fluids such as chlorofluorocarbons either as a dielectric or as a coolant, and which discharges very little waste heat into the surrounding air. A first magnetic switch has cooling channels formed therethrough to facilitate the removal of excess heat. The first magnetic switch is mounted on a printed circuit board. A pulse transformer comprised of a plurality of discrete electrically insulated and magnetically coupled units is also mounted on said printed board and is electrically coupled to the first magnetic switch. The pulse transformer also has cooling means attached thereto for removing heat from the pulse transformer. A second magnetic switch also having cooling means for removing excess heat is electrically coupled to the pulse transformer. Thus, the present invention is able to provide high voltage pulses of short duration at a high repetition rate and high peak power output without the use of environmentally unacceptable fluids and without discharging significant waste heat into the surrounding air. 9 figs.

  4. Water cooled steam jet

    DOEpatents

    Wagner, Jr., Edward P.

    1999-01-01

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed therebetween. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock.

  5. Turbine blade cooling

    DOEpatents

    Staub, F.W.; Willett, F.T.

    1999-07-20

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number. 13 figs.

  6. Turbine blade cooling

    DOEpatents

    Staub, Fred Wolf; Willett, Fred Thomas

    2000-01-01

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number.

  7. Turbine blade cooling

    DOEpatents

    Staub, Fred Wolf; Willett, Fred Thomas

    1999-07-20

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number.

  8. Hydronic rooftop cooling systems

    DOEpatents

    Bourne, Richard C.; Lee, Brian Eric; Berman, Mark J.

    2008-01-29

    A roof top cooling unit has an evaporative cooling section that includes at least one evaporative module that pre-cools ventilation air and water; a condenser; a water reservoir and pump that captures and re-circulates water within the evaporative modules; a fan that exhausts air from the building and the evaporative modules and systems that refill and drain the water reservoir. The cooling unit also has a refrigerant section that includes a compressor, an expansion device, evaporator and condenser heat exchangers, and connecting refrigerant piping. Supply air components include a blower, an air filter, a cooling and/or heating coil to condition air for supply to the building, and optional dampers that, in designs that supply less than 100% outdoor air to the building, control the mixture of return and ventilation air.

  9. Stochastic cooling at Fermilab

    SciTech Connect

    Marriner, J.

    1986-08-01

    The topics discussed are the stochastic cooling systems in use at Fermilab and some of the techniques that have been employed to meet the particular requirements of the anti-proton source. Stochastic cooling at Fermilab became of paramount importance about 5 years ago when the anti-proton source group at Fermilab abandoned the electron cooling ring in favor of a high flux anti-proton source which relied solely on stochastic cooling to achieve the phase space densities necessary for colliding proton and anti-proton beams. The Fermilab systems have constituted a substantial advance in the techniques of cooling including: large pickup arrays operating at microwave frequencies, extensive use of cryogenic techniques to reduce thermal noise, super-conducting notch filters, and the development of tools for controlling and for accurately phasing the system.

  10. Water cooled steam jet

    DOEpatents

    Wagner, E.P. Jr.

    1999-01-12

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed there between. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock. 2 figs.

  11. Silica and Pyroxene in IVA Irons; Possible Formation of the IVA Magma by Impact Melting and Reduction of L-LL-Chondrite Materials Followed by Crystallization and Cooling

    NASA Technical Reports Server (NTRS)

    Wasson, John T.; Matsunami, Yoshiyuki; Rubin, Alan E.

    2006-01-01

    into IVA irons after the initial magma crystallized. Because the y-iron crystals in SJN are typically about 5 cm across, an order of magnitude smaller than in IVA irons that do not contain massive silicates, we infer that the metal was in the gamma-iron field when the silicates were injected. The SJN and Steinbach silicate compositions are near the low-Ca-pyroxene/silica eutectic compositions. We suggest that a tectonic event produced a eutectic-like liquid and injected it together with unmelted pyroxene grains into fissures in the solid metal core. Published estimates of IVA metallographic cooling rates range from 20 to 3000 K/Ma, leading to a hypothesized breakup of the core during a major impact followed by scrambling of the core and mantle debris [Haack, H., Scott, E.R.D., Love, S.G., Brearley, A. 1996. Thermal histories of IVA stony-iron and iron meteorites: evidence for asteroid fragmentation and reaccretion. Geochim. Cosmochim. Acta 60, 3103-3113]. This scrambling model is physically implausible and cannot explain the strong correlation of estimated cooling rates with metal composition. Previous workers concluded that the low-Ca clinopyroxene in SJN and Steinbach formed from protopyroxene by quenching at a cooling rate of 10(sup 12) K/Ma, and suggested that this also supported an impact-scrambling model. This implausible spike in cooling rate by a factor of 10(sup 10) can be avoided if the low-Ca clinopyroxene were formed by a late shock event that converted orthopyroxene to clinopyroxene followed by minimal growth in the clinopyroxene field, probably because melt was also produced. We suggest that metallographic cooling-rate estimates (e.g., based on island taenite) giving similar values throughout the metal compositional range are more plausible, and that the IVA parent asteroid can be modeled by monotonic cooling followed by a high-temperature impact event that introduced silicates into the metal and a low-temperature impact event that partially converted

  12. Silica and pyroxene in IVA irons; possible formation of the IVA magma by impact melting and reduction of L-LL-chondrite materials followed by crystallization and cooling

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Matsunami, Yoshiyuki; Rubin, Alan E.

    2006-06-01

    -iron crystals in SJN are typically about 5 cm across, an order of magnitude smaller than in IVA irons that do not contain massive silicates, we infer that the metal was in the γ-iron field when the silicates were injected. The SJN and Steinbach silicate compositions are near the low-Ca-pyroxene/silica eutectic compositions. We suggest that a tectonic event produced a eutectic-like liquid and injected it together with unmelted pyroxene grains into fissures in the solid metal core. Published estimates of IVA metallographic cooling rates range from 20 to 3000 K/Ma, leading to a hypothesized breakup of the core during a major impact followed by scrambling of the core and mantle debris [Haack, H., Scott, E.R.D., Love, S.G., Brearley, A. 1996. Thermal histories of IVA stony-iron and iron meteorites: evidence for asteroid fragmentation and reaccretion. Geochim. Cosmochim. Acta60, 3103-3113]. This scrambling model is physically implausible and cannot explain the strong correlation of estimated cooling rates with metal composition. Previous workers concluded that the low-Ca clinopyroxene in SJN and Steinbach formed from protopyroxene by quenching at a cooling rate of 10 12 K/Ma, and suggested that this also supported an impact-scrambling model. This implausible spike in cooling rate by a factor of 10 10 can be avoided if the low-Ca clinopyroxene were formed by a late shock event that converted orthopyroxene to clinopyroxene followed by minimal growth in the clinopyroxene field, probably because melt was also produced. We suggest that metallographic cooling-rate estimates (e.g., based on island taenite) giving similar values throughout the metal compositional range are more plausible, and that the IVA parent asteroid can be modeled by monotonic cooling followed by a high-temperature impact event that introduced silicates into the metal and a low-temperature impact event that partially converted orthopyroxene into low-Ca clinopyroxene.

  13. Beam cooling with ionization losses

    NASA Astrophysics Data System (ADS)

    Rubbia, C.; Ferrari, A.; Kadi, Y.; Vlachoudis, V.

    2006-12-01

    This novel type of Ionization Cooling is an effective method in order to enhance the (strong) interaction probability of slow (few MeV/A) ions stored in a small ring. The many traversals through a thin target strongly improve the nuclear reaction rate with respect to a single-pass collision, in a steady configuration in which ionization losses of a target "foil" (typically few hundred μg/cm 2 thick) are continuously recovered by an RF-cavity. With a flat foil, betatron oscillations are "cooled", but the momentum spread diverges exponentially, since faster (slower) particles ionize less (more) than the average. In order to "cool" the beam also longitudinally, a chromaticity has to be introduced with a wedge-shaped "foil". Therefore, in equilibrium conditions, multiple scattering and straggling are both balanced by phase-space compression. Classic Ionization Cooling [A.A. Kolomensky, Atomnaya Energiya 19 (1965) 534; Yu.M. Ado, V.I. Balbekov, Atomnaya Energiya 31(1) (1971) 40-44; A.N. Skrinsky, V.V. Parkhomchuk, Sov. J. Nucl. Phys. 12 (1981) 3; E.A. Perevendentsev, A.N. Skrinsky, in: Proceedings of the 12th International Conference on High Energy Acceleration, 1983, p. 485] is designed to cool the direct beam until it has been compressed and extracted for further use. In practice, this limits its applicability to non-interacting muon beams. Instead, in this new method, applicable to strongly interacting collisions, the circulating beam is not extracted. Ionization cooling provides "in situ" storage of the beam until it is converted by a nuclear interaction with the target. Simple reactions—for instance 7Li+D→8Li+p—are more favourably produced in the "mirror" kinematical frame, namely with a heavier ion colliding against a gas-jet D 2 target. Kinematics is generally very favourable, with angles in a narrow angular cone (around ˜10° for the mentioned reaction) and with a relatively concentrated outgoing energy spectrum which allows an efficient collection of 8

  14. The initial cooling of pahoehoe flow lobes

    USGS Publications Warehouse

    Keszthelyi, L.; Denlinger, R.

    1996-01-01

    In this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows. The accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation. This model is constructed from the physical phenomena observed to control the initial cooling of pahoehoe flows and is not an empirical fit to field data. We find that the only significant processes are (a) heat loss by thermal radiation, (b) heat loss by atmospheric convection, (c) heat transport within the flow by conduction with temperature and porosity-dependent thermal properties, and (d) the release of latent heat during crystallization. The numerical model is better able to reproduce field measurements made in Hawai'i between 1989 and 1993 than other published thermal models. By adjusting one parameter at a time, the effect of each of the input parameters on the cooling rate was determined. We show that: (a) the surfaces of porous flows cool more quickly than the surfaces of dense flows, (b) the surface cooling is very sensitive to the efficiency of atmospheric convective cooling, and (c) changes in the glass forming tendency of the lava may have observable petrographic and thermal signatures. These model results provide a quantitative explanation for the recently observed relationship between the surface cooling rate of pahoehoe lobes and the porosity of those lobes (Jones 1992, 1993). The predicted sensitivity of cooling to atmospheric convection suggests a simple field experiment for verification, and the model provides a tool to begin studies of the dynamic crystallization of real lavas. Future versions of the model can also be made applicable to extraterrestrial, submarine, silicic, and pyroclastic flows.

  15. Current Pulses Momentarily Enhance Thermoelectric Cooling

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey; Fleurial, Jean-Pierre; Caillat, Thierry; Chen, Gang; Yang, Rong Gui

    2004-01-01

    The rates of cooling afforded by thermoelectric (Peltier) devices can be increased for short times by applying pulses of electric current greater than the currents that yield maximum steady-state cooling. It has been proposed to utilize such momentary enhancements of cooling in applications in which diode lasers and other semiconductor devices are required to operate for times of the order of milliseconds at temperatures too low to be easily obtainable in the steady state. In a typical contemplated application, a semiconductor device would be in contact with the final (coldest) somewhat taller stage of a multistage thermoelectric cooler. Steady current would be applied to the stages to produce steady cooling. Pulsed current would then be applied, enhancing the cooling of the top stage momentarily. The principles of operation are straightforward: In a thermoelectric device, the cooling occurs only at a junction at one end of the thermoelectric legs, at a rate proportional to the applied current. However, Joule heating occurs throughout the device at a rate proportional to the current squared. Hence, in the steady state, the steady temperature difference that the device can sustain increases with current only to the point beyond which the Joule heating dominates. If a pulse of current greater than the optimum current (the current for maximum steady cooling) is applied, then the junction becomes momentarily cooled below its lowest steady temperature until thermal conduction brings the resulting pulse of Joule heat to the junction and thereby heats the junction above its lowest steady temperature. A theoretical and experimental study of such transient thermoelectric cooling followed by transient Joule heating in response to current pulses has been performed. The figure presents results from one of the experiments. The study established the essential parameters that characterize the pulse cooling effect, including the minimum temperature achieved, the maximum

  16. Geminga: A cooling superfluid neutron star

    NASA Technical Reports Server (NTRS)

    Page, Dany

    1994-01-01

    We compare the recent temperature estimate for Geminga with neutron star cooling models. Because of its age (approximately 3.4 x 10(exp 5) yr), Geminga is in the photon cooling era. We show that its surface temperature (approximately 5.2 x 10(exp 5) K) can be understood by both types of neutrino cooling scenarios, i.e., slow neutrino cooling by the modified Urca process or fast neutrino cooling by the direct Urca process or by some exotic matter, and thus does not allow us to discriminate between these two competing schemes. However, for both types of scenarios, agreement with the observed temperature can only be obtained if baryon pairing is present in most, if not all, of the core of the star. Within the slow neutrino cooling scenario, early neutrino cooling is not sufficient to explain the observed low temperature, and extensive pairing in the core is necessary to reduce the specific heat and increase the cooling rate in the present photon cooling era. Within all the fast neutrino cooling scenarios, pairing is necessary throughout the whole core to control the enormous early neutrino emission which, without pairing suppression, would result in a surface temperature at the present time much lower than observed. We also comment on the recent temperature estimates for PSR 0656+14 and PSR 1055-52, which pertain to the same photon cooling era. If one assumes that all neutron stars undergo fast neutrino cooling, then these two objects also provide evidence for extensive baryon pairing in their core; but observational uncertainties also permit a more conservative interpretation, with slow neutrino emission and no pairing at all. We argue though that observational evidence for the slow neutrino cooling model (the 'standard' model) is in fact very dim and that the interpretation of the surface temperature of all neutron stars could be done with a reasonable theoretical a priori within the fast neutrino cooling scenarios only. In this case, Geminga, PSR 0656+14, and PSR

  17. Turbine airfoil with an internal cooling system having vortex forming turbulators

    SciTech Connect

    Lee, Ching-Pang

    2014-12-30

    A turbine airfoil usable in a turbine engine and having at least one cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels having a plurality of turbulators protruding from an inner surface and positioned generally nonorthogonal and nonparallel to a longitudinal axis of the airfoil cooling channel. The configuration of turbulators may create a higher internal convective cooling potential for the blade cooling passage, thereby generating a high rate of internal convective heat transfer and attendant improvement in overall cooling performance. This translates into a reduction in cooling fluid demand and better turbine performance.

  18. MEIC electron cooling program

    SciTech Connect

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is a high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.

  19. MEIC electron cooling program

    DOE PAGES

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is amore » high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.« less

  20. Thermal Energy for Space Cooling--Federal Technology Alert

    SciTech Connect

    Brown, Daryl R.

    2000-12-31

    Cool storage technology can be used to significantly reduce energy costs by allowing energy-intensive, electrically driven cooling equipment to be predominantly operated during off peak hours when electricity rates are lower. This Federal Technology Alert, which is sponsored by DOE's Federal Energy Management Program (FEMP), describes the basic types of cool storage technologies and cooling system integration options. In addition, it defines the savings potential in the federal sector, presents application advice, and describes the performance experience of specific federal users. The results of a case study of a GSA building using cool storage technology are also provided.

  1. Cooling, AGN Feedback, and Star Formation in Simulated Cool-core Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg L.; Ruszkowski, Mateusz; Voit, G. Mark; O’Shea, Brian W.; Donahue, Megan

    2015-10-01

    Numerical simulations of active galactic nuclei (AGNs) feedback in cool-core galaxy clusters have successfully avoided classical cooling flows, but often produce too much cold gas. We perform adaptive mesh simulations that include momentum-driven AGN feedback, self-gravity, star formation, and stellar feedback, focusing on the interplay between cooling, AGN heating, and star formation in an isolated cool-core cluster. Cold clumps triggered by AGN jets and turbulence form filamentary structures tens of kpc long. This cold gas feeds both star formation and the supermassive black hole (SMBH), triggering an AGN outburst that increases the entropy of the intracluster medium (ICM) and reduces its cooling rate. Within 1–2 Gyr, star formation completely consumes the cold gas, leading to a brief shutoff of the AGN. The ICM quickly cools and redevelops multiphase gas, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. There is good agreement between our simulated cluster and the observations of cool-core clusters. ICM cooling is dynamically balanced by AGN heating, and a cool-core appearance is preserved. The minimum cooling time to free-fall time ratio typically varies between a few and ≳ 20. The star formation rate (SFR) covers a wide range, from 0 to a few hundred {M}ȯ {{yr}}-1, with an average of ∼ 40 {M}ȯ {{yr}}-1. The instantaneous SMBH accretion rate shows large variations on short timescales, but the average value correlates well with the SFR. Simulations without stellar feedback or self-gravity produce qualitatively similar results, but a lower SMBH feedback efficiency (0.1% compared to 1%) results in too many stars.

  2. Cryogenic generator cooling

    NASA Astrophysics Data System (ADS)

    Eckels, P. W.; Fagan, T. J.; Parker, J. H., Jr.; Long, L. J.; Shestak, E. J.; Calfo, R. M.; Hannon, W. F.; Brown, D. B.; Barkell, J. W.; Patterson, A.

    The concept for a hydrogen cooled aluminum cryogenic generator was presented by Schlicher and Oberly in 1985. Following their lead, this paper describes the thermal design of a high voltage dc, multimegawatt generator of high power density. The rotor and stator are cooled by saturated liquid and supercritical hydrogen, respectively. The brushless exciter on the same shaft is also cooled by liquid hydrogen. Component development testing is well under way and some of the test results concerning the thermohydraulic performance of the conductors are reported. The aluminum cryogenic generator's characteristics are attractive for hydrogen economy applications.

  3. 16 CFR Appendix H to Part 305 - Cooling Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Manufacturer's rated cooling capacities (Btu's/hr.) Range of SEER's Low High Single Package Units Central Air Conditioners (Cooling Only): All capacities 10.6 16.5 Heat Pumps (Cooling Function): All capacities 10.6 16.0 Split System Units Central Air Conditioners (Cooling Only): All capacities 10.9 23.0 Heat Pumps...

  4. How does gas cool in dark matter haloes?

    NASA Astrophysics Data System (ADS)

    Viola, M.; Monaco, P.; Borgani, S.; Murante, G.; Tornatore, L.

    2008-01-01

    In order to study the process of cooling in dark matter haloes and assess how well simple models can represent it, we run a set of radiative smoothed particle hydrodynamics (SPH) simulations of isolated haloes, with gas sitting initially in hydrostatic equilibrium within Navarro-Frenk-White potential wells. Simulations include radiative cooling and a scheme to convert high-density cold gas particles into collisionless stars, neglecting any astrophysical source of energy feedback. After having assessed the numerical stability of the simulations, we compare the resulting evolution of the cooled mass with the predictions of the classical cooling model of White & Frenk and of the cooling model proposed in the MORGANA code of galaxy formation. We find that the classical model predicts fractions of cooled mass which, after about 2 central cooling times, are about one order of magnitude smaller than those found in simulations. Although this difference decreases with time, after 8 central cooling times, when simulations are stopped, the difference still amounts to a factor of 2-3. We ascribe this difference to the lack of validity of the assumption that a mass shell takes one cooling time, as computed on the initial conditions, to cool to very low temperature. Indeed, we find from simulations that cooling SPH particles take most time in travelling, at roughly constant temperature and increasing density, from their initial position to a central cooling region, where they quickly cool down to ~104 K. We show that in this case the total cooling time is shorter than that computed on the initial conditions, as a consequence of the stronger radiative losses associated to the higher density experienced by these particles. As a consequence the mass cooling flow is stronger than that predicted by the classical model. The MORGANA model, which computes the cooling rate as an integral over the contribution of cooling shells and does not make assumptions on the time needed by shells to

  5. TRANSVERSE OSCILLATIONS OF A COOLING CORONAL LOOP

    SciTech Connect

    Morton, R. J.; Erdelyi, R. E-mail: Robertus@sheffield.ac.u

    2009-12-10

    Here we present an investigation into how cooling of the plasma influences the oscillation properties (e.g., eigenfunctions and eigenfrequencies) of transverse (i.e., kink) magnetohydrodynamic (MHD) waves in a compressible magnetic flux tube embedded in a gravitationally stratified and uniformly magnetized atmosphere. The cooling is introduced via a temperature-dependent density profile. A time-dependent governing equation is derived and an approximate zeroth-order solution is then obtained. From this the influence of cooling on the behavior of the eigenfrequencies and eigenfunctions of the transverse MHD waves is determined for representative cooling timescales. It is shown analytically, as the loop cools, how the amplitude of the perturbations is found to decrease as time increases. For cooling timescales of 900-2000 s (as observed in typical EUV loops), it is shown that the cooling has important and relevant influence on the damping times of loop oscillations. Next, the theory is put to the test. The damping due to cooling is fitted to a representative observation of standing kink oscillation of EUV loops. It is also shown with an explicit approximate analytical form, how the period of the fundamental and first harmonic of the kink mode changes with time as the loop cools. A consequence of this is that the value of the period ratio P {sub 1}/P {sub 2}, a tool that is popular in magneto-seismological studies in coronal diagnostics, decreases from the value of a uniform loop, 2, as the temperature decreases. The rate of change in P {sub 1}/P {sub 2} is dependent upon the cooling timescale and is well within the observable range for typical EUV loops. Further to this, the magnitude of the anti-node shift of the eigenfunctions of the first harmonic is shown to continually increase as the loop cools, giving additional impetus to the use of spatial magneto-seismology of the solar atmosphere. Finally, we suggest that measurements of the rate of change in the

  6. Near term application of water cooling

    NASA Astrophysics Data System (ADS)

    Horner, M. W.; Caruvana, A.; Cohn, A.; Smith, D. P.

    1980-03-01

    The paper presents studies of combined gas and steam-turbine cycles related to the near term application of water cooling technology to the commercial gas turbine operating on heavy residual oil or coal derived liquid fuels. Water cooling promises significant reduction of hot corrosion and ash deposition at the turbine first-stage nozzle. It was found that: (1) corrosion of some alloys in the presence of alkali contaminant was less as metal temperatures were lowered to the 800-1000 F range, (2) the rate of ash deposition is increased for air-cooled and water-cooled nozzles at the 2060 F turbine firing temperature compared to 1850 F, (3) the ash deposit for the water cooled nozzle was lighter and more easily removed at both 1850 and 2050 F, (4) on-line nutshelling was effective on the water-cooled nozzles even at 2050 F, and (5) the data indicates that the rate of ash deposition may be sensitive to surface wall temperatures.

  7. Warm and Cool Dinosaurs.

    ERIC Educational Resources Information Center

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  8. Stimulated radiative laser cooling

    NASA Astrophysics Data System (ADS)

    Muys, P.

    2008-04-01

    Building a refrigerator based on the conversion of heat into optical energy is an ongoing engineering challenge. Under well-defined conditions, spontaneous anti-Stokes fluorescence of a dopant material in a host matrix is capable of lowering the host temperature. The fluorescence is conveying away a part of the thermal energy stored in the vibrational oscillations of the host lattice. In particular, applying this principle to the cooling of (solid-state) lasers opens up many potential device applications, especially in the domain of high-power lasers. In this paper, an alternative optical cooling scheme is outlined, leading to the radiative cooling of solid-state lasers. It is based on converting the thermal energy stored in the host into optical energy by means of a stimulated nonlinear process, rather than a spontaneous process. This should lead to better cooling efficiencies and a higher potential of applying the principle for device applications.

  9. Why Exercise Is Cool

    MedlinePlus

    ... Homework? Here's Help White House Lunch Recipes Why Exercise Is Cool KidsHealth > For Kids > Why Exercise Is ... day and your body will thank you later! Exercise Makes Your Heart Happy You may know that ...

  10. Cooling system for superconducting magnet

    DOEpatents

    Gamble, B.B.; Sidi-Yekhlef, A.

    1998-12-15

    A cooling system is configured to control the flow of a refrigerant by controlling the rate at which the refrigerant is heated, thereby providing an efficient and reliable approach to cooling a load (e.g., magnets, rotors). The cooling system includes a conduit circuit connected to the load and within which a refrigerant circulates; a heat exchanger, connected within the conduit circuit and disposed remotely from the load; a first and a second reservoir, each connected within the conduit, each holding at least a portion of the refrigerant; a heater configured to independently heat the first and second reservoirs. In a first mode, the heater heats the first reservoir, thereby causing the refrigerant to flow from the first reservoir through the load and heat exchanger, via the conduit circuit and into the second reservoir. In a second mode, the heater heats the second reservoir to cause the refrigerant to flow from the second reservoir through the load and heat exchanger via the conduit circuit and into the first reservoir. 3 figs.

  11. Cooling system for superconducting magnet

    DOEpatents

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed

    1998-01-01

    A cooling system is configured to control the flow of a refrigerant by controlling the rate at which the refrigerant is heated, thereby providing an efficient and reliable approach to cooling a load (e.g., magnets, rotors). The cooling system includes a conduit circuit connected to the load and within which a refrigerant circulates; a heat exchanger, connected within the conduit circuit and disposed remotely from the load; a first and a second reservoir, each connected within the conduit, each holding at least a portion of the refrigerant; a heater configured to independently heat the first and second reservoirs. In a first mode, the heater heats the first reservoir, thereby causing the refrigerant to flow from the first reservoir through the load and heat exchanger, via the conduit circuit and into the second reservoir. In a second mode, the heater heats the second reservoir to cause the refrigerant to flow from the second reservoir through the load and heat exchanger via the conduit circuit and into the first reservoir.

  12. Terrestrial cooling and solar variability

    NASA Technical Reports Server (NTRS)

    Agee, E. M.

    1982-01-01

    Observational evidence from surface temperature records is presented and discussed which suggests a significant cooling trend over the Northern Hemisphere from 1940 to the present. This cooling trend is associated with an increase of the latitudinal gradient of temperature and the lapse rate, as predicted by climate models with decreased solar input and feedback mechanisms. Evidence suggests that four of these 80- to 100-year cycles of global surface temperature fluctuation may have occurred, and in succession, from 1600 to the present. Interpretation of sunspot activity were used to infer a direct thermal response of terrestrial temperature to solar variability on the time scale of the Gleissberg cycle (90 years, an amplitude of the 11-year cycles). A physical link between the sunspot activity and the solar parameter is hypothesized. Observations of sensible heat flux by stationary planetary waves and transient eddies, as well as general circulation modeling results of these processes, were examined from the viewpoint of the hypothesis of cooling due to reduced insolation.

  13. Transpiration cooled throat for hydrocarbon rocket engines

    NASA Technical Reports Server (NTRS)

    May, Lee R.; Burkhardt, Wendel M.

    1991-01-01

    The objective for the Transpiration Cooled Throat for Hydrocarbon Rocket Engines Program was to characterize the use of hydrocarbon fuels as transpiration coolants for rocket nozzle throats. The hydrocarbon fuels investigated in this program were RP-1 and methane. To adequately characterize the above transpiration coolants, a program was planned which would (1) predict engine system performance and life enhancements due to transpiration cooling of the throat region using analytical models, anchored with available data; (2) a versatile transpiration cooled subscale rocket thrust chamber was designed and fabricated; (3) the subscale thrust chamber was tested over a limited range of conditions, e.g., coolant type, chamber pressure, transpiration cooled length, and coolant flow rate; and (4) detailed data analyses were conducted to determine the relationship between the key performance and life enhancement variables.

  14. Stochastic cooling of a high energy collider

    SciTech Connect

    Blaskiewicz, M.; Brennan, J.M.; Lee, R.C.; Mernick, K.

    2011-09-04

    Gold beams in RHIC revolve more than a billion times over the course of a data acquisition session or store. During operations with these heavy ions the event rates in the detectors decay as the beams diffuse. A primary cause for this beam diffusion is small angle Coloumb scattering of the particles within the bunches. This intra-beam scattering (IBS) is particularly problematic at high energy because the negative mass effect removes the possibility of even approximate thermal equilibrium. Stochastic cooling can combat IBS. A theory of bunched beam cooling was developed in the early eighties and stochastic cooling systems for the SPS and the Tevatron were explored. Cooling for heavy ions in RHIC was also considered.

  15. Evaluation of advanced cooling therapy's esophageal cooling device for core temperature control.

    PubMed

    Naiman, Melissa; Shanley, Patrick; Garrett, Frank; Kulstad, Erik

    2016-05-01

    Managing core temperature is critical to patient outcomes in a wide range of clinical scenarios. Previous devices designed to perform temperature management required a trade-off between invasiveness and temperature modulation efficiency. The Esophageal Cooling Device, made by Advanced Cooling Therapy (Chicago, IL), was developed to optimize warming and cooling efficiency through an easy and low risk procedure that leverages heat transfer through convection and conduction. Clinical data from cardiac arrest, fever, and critical burn patients indicate that the Esophageal Cooling Device performs very well both in terms of temperature modulation (cooling rates of approximately 1.3°C/hour, warming of up to 0.5°C/hour) and maintaining temperature stability (variation around goal temperature ± 0.3°C). Physicians have reported that device performance is comparable to the performance of intravascular temperature management techniques and superior to the performance of surface devices, while avoiding the downsides associated with both. PMID:27043177

  16. Laser cooling of solids

    SciTech Connect

    Epstein, Richard I; Sheik-bahae, Mansoor

    2008-01-01

    We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.

  17. Refrigerant directly cooled capacitors

    DOEpatents

    Hsu, John S.; Seiber, Larry E.; Marlino, Laura D.; Ayers, Curtis W.

    2007-09-11

    The invention is a direct contact refrigerant cooling system using a refrigerant floating loop having a refrigerant and refrigeration devices. The cooling system has at least one hermetic container disposed in the refrigerant floating loop. The hermetic container has at least one electronic component selected from the group consisting of capacitors, power electronic switches and gating signal module. The refrigerant is in direct contact with the electronic component.

  18. WATER COOLED RETORT COVER

    DOEpatents

    Ash, W.J.; Pozzi, J.F.

    1962-05-01

    A retort cover is designed for use in the production of magnesium metal by the condensation of vaporized metal on a collecting surface. The cover includes a condensing surface, insulating means adjacent to the condensing surface, ind a water-cooled means for the insulating means. The irrangement of insulation and the cooling means permits the magnesium to be condensed at a high temperature and in massive nonpyrophoric form. (AEC)

  19. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  20. Biomedical Application of Aerospace Personal Cooling Systems

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Lee, Hank C.; Montgomery, Leslie D.; Webbon, Bruce W.; Kliss, Mark (Technical Monitor)

    1997-01-01

    Personal thermoregulatory systems which are used by astronauts to alleviate thermal stress during extravehicular activity have been applied to the therapeutic management of multiple sclerosis. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to compare the effectiveness of two passive and two active cooling vests and to measure the body temperature and circulatory changes produced by each cooling vest configuration. The MicroClimate Systems and the Life Enhancement Tech(LET) lightweight liquid cooling vests, the Steele Vest and LET's Zipper Front Garment were used to cool the chest region of 10 male and female subjects (25 to 55 yr.) in this study. Calf, forearm and finger blood flows were measured using a tetrapolar impedance rheograph. The subjects, seated in an upright position at normal room temperature (approx.22C), were tested for 60 min. with the cooling system operated at its maximum cooling capacity. Blood flows were recorded continuously using a computer data acquisition system with a sampling frequency of 250 Hz. Oral, right and left ear temperatures and cooling system parameters were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; respiration; and an activity index were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. In general, the male and female subjects' oral and ear temperature responses to cooling were similar for all vest configurations tested. Oral temperatures during the recovery period were significantly (P<0.05) lower than during the control period, approx. 0.2 - 0.5C, for both men and women wearing any of the four different garments. The corresponding ear temperatures were significantly (P<0.05) decreased approx.0.2 - 0.4C by the end of the recovery period. Compared to the control period, no significant differences were found in rectal temperatures during cooling and

  1. Gas-cooled nuclear reactor

    DOEpatents

    Peinado, Charles O.; Koutz, Stanley L.

    1985-01-01

    A gas-cooled nuclear reactor includes a central core located in the lower portion of a prestressed concrete reactor vessel. Primary coolant gas flows upward through the core and into four overlying heat-exchangers wherein stream is generated. During normal operation, the return flow of coolant is between the core and the vessel sidewall to a pair of motor-driven circulators located at about the bottom of the concrete pressure vessel. The circulators repressurize the gas coolant and return it back to the core through passageways in the underlying core structure. If during emergency conditions the primary circulators are no longer functioning, the decay heat is effectively removed from the core by means of natural convection circulation. The hot gas rising through the core exits the top of the shroud of the heat-exchangers and flows radially outward to the sidewall of the concrete pressure vessel. A metal liner covers the entire inside concrete surfaces of the concrete pressure vessel, and cooling tubes are welded to the exterior or concrete side of the metal liner. The gas coolant is in direct contact with the interior surface of the metal liner and transfers its heat through the metal liner to the liquid coolant flowing through the cooling tubes. The cooler gas is more dense and creates a downward convection flow in the region between the core and the sidewall until it reaches the bottom of the concrete pressure vessel when it flows radially inward and up into the core for another pass. Water is forced to flow through the cooling tubes to absorb heat from the core at a sufficient rate to remove enough of the decay heat created in the core to prevent overheating of the core or the vessel.

  2. Transpiration cooling in hypersonic flight

    NASA Technical Reports Server (NTRS)

    Tavella, Domingo; Roberts, Leonard

    1989-01-01

    A preliminary numerical study of transpiration cooling applied to a hypersonic configuration is presented. Air transpiration is applied to the NASA all-body configuration flying at an altitude of 30500 m with a Mach number of 10.3. It was found that the amount of heat disposal by convection is determined primarily by the local geometry of the aircraft for moderate rates of transpiration. This property implies that different areas of the aircraft where transpiration occurs interact weakly with each other. A methodology for quick assessments of the transpiration requirements for a given flight configuration is presented.

  3. Why most ``dry`` rocks should cool ``wet``

    SciTech Connect

    Kohn, M.J.

    1999-04-01

    A new consideration of oxygen isotope resetting among metamorphic minerals is made accounting for (1) the possibility of f{sub H{sub 2}O}-buffering by typical mineral assemblages during cooling and (2) experimental data that show that high f{sub H{sub 2}O} correlates with high diffusion rates. Isotope closure temperatures in buffered rocks are intermediate between simpler predictions based on wet (1 kbar hydrothermal) and dry (P {le} 1 atm, H{sub 2}O-absent) diffusion experiments, but are typically within {approximately}50 C of closure temperature estimates that use wet diffusion rates, yet 200--300 C different from dry. Even though many rocks may be dry in that they lack a hydrous fluid that is physically present during cooling, buffering of f{sub H{sub 2}O} results in quasi-wet diffusion rates. Re-evaluation of published data shows that most rocks indeed exhibit substantial isotope resetting that is best matched by predictions of f{sub H{sub 2}O}-buffering models. Wet- and dry-diffusion models somewhat overestimate and greatly underestimate resetting respectively. Previous interpretations invoking dry diffusion rates may derive from erroneous fractionation factors or faster cooling rates than assumed. The rare preservation of isotope closure temperatures that are higher than predicted may reflect faster than expected cooling rates or extraordinarily los f{sub H{sub 2}O} in conjunction with anhydrous assemblages.

  4. Comparing Social Stories™ to Cool versus Not Cool

    ERIC Educational Resources Information Center

    Leaf, Justin B.; Mitchell, Erin; Townley-Cochran, Donna; McEachin, John; Taubman, Mitchell; Leaf, Ronald

    2016-01-01

    In this study we compared the cool versus not cool procedure to Social Stories™ for teaching various social behaviors to one individual diagnosed with autism spectrum disorder. The researchers randomly assigned three social skills to the cool versus not cool procedure and three social skills to the Social Stories™ procedure. Naturalistic probes…

  5. Effects of regolith/megaregolith insulation on the cooling histories of differentiated asteroids

    NASA Astrophysics Data System (ADS)

    Haack, H.; Rasmussen, K. L.; Warren, P. H.

    1990-04-01

    The cooling histories of differentiated asteroids are calculated employing a variety of thermal-conductivity structures to simulate the potential insulating effects of regolith and megaregolith layers on the cooling rate. It was found that a combination of relatively thick megaregolith and regolith can potentially reduce the core cooling rate by more than a factor of 10 below the rate predicted by models with conventional thermal conductivity structure. Thus, differences in cratering (regolith production) histories may have resulted in radically different cooling rates for asteroids of similar radius, or in similar cooling rates from asteroids of different radius.

  6. Evaluation of three commercial microclimate cooling systems

    NASA Astrophysics Data System (ADS)

    Cadarette, Bruce S.; Decristofano, Barry S.; Speckman, Karen N.; Sawka, Michael N.

    1988-11-01

    Three commercially available microclimate cooling systems were evaluated for their ability to reduce heat stress in men exercising in a hot environment while wearing high insulative, low permeability clothing. The cooling systems were: (1) ILC Dover Model 19 Coolvest (ILC) (2) LSSI Coolhead(LSSI), and (3) Thermacor Cooling vest (THERM). Endurance Time (ET), Heart Rate (HR), rectal temperature (Tre), mean skin temperature (TSK), Sweating Rate (SR), Rated Perceived Exertion (RPE) and Thermal Sensation (TS) were measured. The subjects self-terminated on all LSSI tests because of headaches. Statistical analyses were performed on data collected at 60 minutes to have values on all subjects. There were no differences in HR, Tre, SR or TS values among the cooling vests. The subjects' TSK was lower (P less than 0.05) for the LSSI than THERM: and RPE values were higher (P less than 0.05) for LSSI than the other two vests. These data suggest an improved physiological response to exercise heat stress with all three commercial systems with the greatest benefit in performance time provided by the ILC cooling system.

  7. Ultrafast Optimal Sideband Cooling under Non-Markovian Evolution

    NASA Astrophysics Data System (ADS)

    Triana, Johan F.; Estrada, Andrés F.; Pachón, Leonardo A.

    2016-05-01

    A sideband cooling strategy that incorporates (i) the dynamics induced by structured (non-Markovian) environments in the target and auxiliary systems and (ii) the optimally time-modulated interaction between them is developed. For the context of cavity optomechanics, when non-Markovian dynamics are considered in the target system, ground state cooling is reached at much faster rates and at a much lower phonon occupation number than previously reported. In contrast to similar current strategies, ground state cooling is reached here for coupling-strength rates that are experimentally accessible for the state-of-the-art implementations. After the ultrafast optimal-ground-state-cooling protocol is accomplished, an additional optimal control strategy is considered to maintain the phonon number as close as possible to the one obtained in the cooling procedure. Contrary to the conventional expectation, when non-Markovian dynamics are considered in the auxiliary system, the efficiency of the cooling protocol is undermined.

  8. Raman sideband cooling of 138 Ba+ on a Zeeman transition

    NASA Astrophysics Data System (ADS)

    Seck, Christopher; Kokish, Mark; Dietrich, Matthew; Odom, Brian

    2016-05-01

    Here, we report motional ground state preparation of a single 138 Ba+ ion using Raman sideband cooling with the two S1/2 Zeeman sublevels. Owing to the small Zeeman splitting, Raman sideband cooling of 138 Ba+ requires only two AOMs and the Doppler cooling lasers. Additionally, we demonstrate coherent operations using a second, far-off-resonant laser driving Raman π-pulses between the two Zeeman sublevels to characterize our mean motional occupation number, Raman sideband cooling frequency resonance, Raman sideband cooling rate, and ion trap motional heating rate. Motional ground state cooling and molecular internal state preparation, both realized in our group, are important elements for molecular quantum logic spectroscopy (mQLS). We are now working towards motional ground state preparation of a 138 Ba+ and AlH+ ion pair for mQLS. Supported by the AFOSR and the NSF.

  9. Cool WISPs for stellar cooling excesses

    NASA Astrophysics Data System (ADS)

    Giannotti, Maurizio; Irastorza, Igor; Redondo, Javier; Ringwald, Andreas

    2016-05-01

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a mild preference for a non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP or a massless HP represent the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO and the massless HP requires a multi TeV energy scale of new physics that might be accessible at the LHC.

  10. Transpiration cooling using air as a coolant

    SciTech Connect

    Kikkawa, Shinzo; Senda, Mamoru; Sakagushi, Katsuji; Shibutani, Hideki )

    1993-02-01

    Transpiration cooling is one of the most effective techniques for protecting a surface exposed to a high-temperature gas stream. In the present paper, the transpiration cooling effectiveness was measured under steady state. Air as a coolant was transpired from the surface of a porous plate exposed to hot gas stream, and the transpiration rate was varied in the range of 0.001 [approximately] 0.006. The transpiration cooling effectiveness was evaluated by measuring the temperature of the upper surface of the plate. Also, a theoretical study was performed and it was clarified that the effectiveness increases with increasing transpiration rate and heat-transfer coefficient of the upper surface. Further, the effectiveness was expressed as a function of the blowing parameter only. The agreement between the experimental results and theoretical ones was satisfactory.

  11. Electron Cooling of Highly Charged Ions in Penning Traps

    SciTech Connect

    Zwicknagel, Guenter

    2006-10-18

    For recent and planned experiments like the CPT-tests with antihydrogen at CERN (ATHENA, ATRAP) or the QED-tests and various other investigations with slow highly charged ions at GSI (HTTRAP), the ions or antiprotons are cooled with electrons or positrons in Penning traps. In many of these applications an efficient and fast cooling is crucial. In particular for electron cooling of highly charged ions, like e.g. of U92+ in HITRAP, sufficiently large cooling rates are mandatory for avoiding too much losses by recombination or charge exchange processes. Here we present calculations of electron cooling and recombination losses of an ensemble of ions in a Penning traps based on a detailed description of the cooling force and the actual radiative ion-electron recombination rate. We focus on the cooling of highly charged ions, namely bare Uranium, in HITRAP. Both the associated cooling times and recombination losses strongly depend on the density of the electrons and the ratio of the number of ions to the number of electrons in the trap. Our analysis shows that electron cooling of bare Uranium with an initial energy of a few keV/u is feasible with a cooling time less than about a second at less than 10 percent recombination losses.

  12. When Newton's cooling law doesn't hold

    SciTech Connect

    Tarnow, E. )

    1994-01-01

    What is the fastest way to cool something If the object is macroscopic it is to lower the surrounding temperature as much as possible and let Newton's cooling law take effect. If we enter the microscopic world where quantum mechanics rules, this procedure may no longer be the best. This is shown in a simple example where we calculate the optimum cooling rate for an asymmetric two-state system.

  13. Raman cooling in silicon photonic crystals

    NASA Astrophysics Data System (ADS)

    Chen, Yin-Chung; Bahl, Gaurav

    2016-03-01

    Laser cooling of solids can be achieved through various photon up-conversion processes including anti-Stokes photoluminescence and anti-Stokes light scattering. While it has been shown that cooling using photoluminescence-based methods can achieve efficiency comparable to that of thermoelectric cooling, the reliance on specific transitions of the rare-earth dopants limits material choice. Light scattering, on the other hand, occurs in all materials, and has the potential to enable cooling in most materials. We show that by engineering the photonic density of states of a material, one can suppress the Stokes process, and enhance the anti-Stokes radiation. We employ the well-known diamond-structured photonic crystal patterned in crystalline silicon to demonstrate theoretically that when operating within a high transparency regime, the net energy removal rate from phonon annihilation can overcome the optical absorption. The engineered photonic density of states can thus enable simultaneous cooling of all Raman-active phonon modes and the net cooling of the solid.

  14. Feasibility of cooling emplacement drifts by ventilation air and effects of pre-cooling intake air by refrigeration

    SciTech Connect

    Yang, Hang; Bhattacharyya, K.K.

    1995-12-01

    This study evaluates effects of applying refrigerated air to cool emplacement drifts and provides a preliminary basis for future design analyses. Evaluations include impacts of airflow rates, intake air temperature, ventilation systems capability, and effectiveness of pre-cooling. Representative results provided from this study include the heat removal capability of ventilation air, effects of refrigerating intake air on continuous cooling, and effects of refrigerating intake air on rapid (blast cooling). It is possible to cool emplacement drifts within a reasonable time period, using airflow at ambient temperature is reasonable quantity. Refrigerating intake air can significantly reduce required cooling time or airflow rate, but it is inefficient as far as power consumption is concerned.

  15. Monitoring Cray Cooling Systems

    SciTech Connect

    Maxwell, Don E; Ezell, Matthew A; Becklehimer, Jeff; Donovan, Matthew J; Layton, Christopher C

    2014-01-01

    While sites generally have systems in place to monitor the health of Cray computers themselves, often the cooling systems are ignored until a computer failure requires investigation into the source of the failure. The Liebert XDP units used to cool the Cray XE/XK models as well as the Cray proprietary cooling system used for the Cray XC30 models provide data useful for health monitoring. Unfortunately, this valuable information is often available only to custom solutions not accessible by a center-wide monitoring system or is simply ignored entirely. In this paper, methods and tools used to harvest the monitoring data available are discussed, and the implementation needed to integrate the data into a center-wide monitoring system at the Oak Ridge National Laboratory is provided.

  16. Passive containment cooling system

    DOEpatents

    Billig, Paul F.; Cooke, Franklin E.; Fitch, James R.

    1994-01-01

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA.

  17. Winds from cool stars

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.

    1995-01-01

    Spectral observations of cool stars enable study of the presence and character of winds and the mass loss process in objects with effective temperatures, gravities, and atmospheric compositions which differ from that of the Sun. A wealth of recent spectroscopic measurements from the Hubble Space Telescope, and the Extreme Ultraviolet Explorer complement high resolution ground-based measures in the optical and infrared spectral regions. Such observations when combined with realistic semi-empirical atmospheric modeling allow us to estimate the physical conditions in the atmospheres and winds of many classes of cool stars. Line profiles support turbulent heating and mass motions. In low gravity stars, evidence is found for relatively fast (approximately 200 km s(exp -1)), warm winds with rapid acceleration occurring in the chromosphere. In some cases outflows commensurate with stellar escape velocities are present. Our current understanding of cool star winds will be reviewed including the implications of stellar observations for identification of atmospheric heating and acceleration processes.

  18. [Selective brain cooling].

    PubMed

    Corrard, F

    1999-01-01

    The brain is especially sensitive to heat stress. To limit the increase of intracranial heat in case of hyperthermia or fever, a system of selective cooling is put on. It includes two heat-exchangers. The first one, in the face and scalp skin, disperses calories through sweat evaporation. The second one is intracranial, close to the arteries which irrigate the brain. They are connected by a vascular network. In these conditions, the arterial blood temperature, of which cerebral temperature depends upon, is reduced by the cooled venous blood which comes from subcutaneous tissues through the skull wall. On feverish children, increasing such a selective cooling by face fanning can limit cerebral thermal stress. PMID:9974103

  19. Passive containment cooling system

    DOEpatents

    Billig, P.F.; Cooke, F.E.; Fitch, J.R.

    1994-01-25

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA. 1 figure.

  20. STOCHASTIC COOLING FOR RHIC.

    SciTech Connect

    BLASKIEWICZ,M.BRENNAN,J.M.CAMERON,P.WEI,J.

    2003-05-12

    Emittance growth due to Intra-Beam Scattering significantly reduces the heavy ion luminosity lifetime in RHIC. Stochastic cooling of the stored beam could improve things considerably by counteracting IBS and preventing particles from escaping the rf bucket [1]. High frequency bunched-beam stochastic cooling is especially challenging but observations of Schottky signals in the 4-8 GHz band indicate that conditions are favorable in RHIC [2]. We report here on measurements of the longitudinal beam transfer function carried out with a pickup kicker pair on loan from FNAL TEVATRON. Results imply that for ions a coasting beam description is applicable and we outline some general features of a viable momentum cooling system for RHIC.

  1. Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

    NASA Technical Reports Server (NTRS)

    Micklow, Gerald J.

    1996-01-01

    The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

  2. Cyclotron resonance cooling by strong laser field

    SciTech Connect

    Tagcuhi, Toshihiro; Mima, Kunioka

    1995-12-31

    Reduction of energy spread of electron beam is very important to increase a total output radiation power in free electron lasers. Although several cooling systems of particle beams such as a stochastic cooling are successfully operated in the accelerator physics, these cooling mechanisms are very slow and they are only applicable to high energy charged particle beams of ring accelerators. We propose here a new concept of laser cooling system by means of cyclotron resonance. Electrons being in cyclotron motion under a strong magnetic field can resonate with circular polarized electromagnetic field, and the resonance take place selectively depending on the velocity of the electrons. If cyclotron frequency of electrons is equal to the frequency of the electromagnetic field, they absorb the electromagnetic field energy strongly, but the other electrons remain unchanged. The absorbed energy will be converted to transverse kinetic energy, and the energy will be dumped into the radiation energy through bremastrahlung. To build a cooling system, we must use two laser beams, where one of them is counter-propagating and the other is co-propagating with electron beam. When the frequency of the counter-propagating laser is tuned with the cyclotron frequency of fast electrons and the co-propagating laser is tuned with the cyclotron frequency of slow electrons, the energy of two groups will approach and the cooling will be achieved. We solve relativistic motions of electrons with relativistic radiation dumping force, and estimate the cooling rate of this mechanism. We will report optimum parameters for the electron beam cooling system for free electron lasers.

  3. Meta-stable low-level accretion rate states or neutron star crust cooling in the Be/X-ray transients V0332+53 and 4U 0115+63

    NASA Astrophysics Data System (ADS)

    Wijnands, R.; Degenaar, N.

    2016-11-01

    The Be/X-ray transients V0332+53 and 4U 0115+63 exhibited giant, type-II outbursts in 2015. Here we present Swift/XRT follow-up observations at the end of those outbursts. Surprisingly, the sources did not decay back to their known quiescent levels but stalled at a (slowly decaying) meta-stable state with luminosities ~10 times that observed in quiescence. The spectra in these states are considerably softer than the outburst spectra and appear to soften in time when the luminosity decreases. The physical mechanism behind these meta-stable states is unclear and they could be due to low-level accretion (either directly onto the neutron stars or onto their magnetospheres) or due to cooling of the accretion-heated neutron star crusts. Based on the spectra, the slowly decreasing luminosities, and the spectral softening, we favour the crust cooling hypothesis but we cannot exclude the accretion scenarios. On top of this meta-stable state, weak accretion events were observed that occurred at periastron passage and may thus be related to regular type-I outbursts.

  4. Research on cooling effectiveness in stepped slot film cooling vane

    NASA Astrophysics Data System (ADS)

    Li, Yulong; Wu, Hong; Zhou, Feng; Rong, Chengjun

    2016-06-01

    As one of the most important developments in air cooling technology for hot parts of the aero-engine, film cooling technology has been widely used. Film cooling hole structure exists mainly in areas that have high temperature, uneven cooling effectiveness issues when in actual use. The first stage turbine vanes of the aero-engine consume the largest portion of cooling air, thereby the research on reducing the amount of cooling air has the greatest potential. A new stepped slot film cooling vane with a high cooling effectiveness and a high cooling uniformity was researched initially. Through numerical methods, the affecting factors of the cooling effectiveness of a vane with the stepped slot film cooling structure were researched. This paper focuses on the cooling effectiveness and the pressure loss in different blowing ratio conditions, then the most reasonable and scientific structure parameter can be obtained by analyzing the results. The results show that 1.0 mm is the optimum slot width and 10.0 is the most reasonable blowing ratio. Under this condition, the vane achieved the best cooling result and the highest cooling effectiveness, and also retained a low pressure loss.

  5. Combustor liner cooling system

    DOEpatents

    Lacy, Benjamin Paul; Berkman, Mert Enis

    2013-08-06

    A combustor liner is disclosed. The combustor liner includes an upstream portion, a downstream end portion extending from the upstream portion along a generally longitudinal axis, and a cover layer associated with an inner surface of the downstream end portion. The downstream end portion includes the inner surface and an outer surface, the inner surface defining a plurality of microchannels. The downstream end portion further defines a plurality of passages extending between the inner surface and the outer surface. The plurality of microchannels are fluidly connected to the plurality of passages, and are configured to flow a cooling medium therethrough, cooling the combustor liner.

  6. Superconductor rotor cooling system

    DOEpatents

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

    2002-01-01

    A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

  7. Superconductor rotor cooling system

    DOEpatents

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

    2004-11-02

    A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

  8. Cyclic cooling algorithm

    SciTech Connect

    Rempp, Florian; Mahler, Guenter; Michel, Mathias

    2007-09-15

    We introduce a scheme to perform the cooling algorithm, first presented by Boykin et al. in 2002, for an arbitrary number of times on the same set of qbits. We achieve this goal by adding an additional SWAP gate and a bath contact to the algorithm. This way one qbit may repeatedly be cooled without adding additional qbits to the system. By using a product Liouville space to model the bath contact we calculate the density matrix of the system after a given number of applications of the algorithm.

  9. Anomalous law of cooling

    SciTech Connect

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton’s law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  10. Anomalous law of cooling

    NASA Astrophysics Data System (ADS)

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  11. Anomalous law of cooling.

    PubMed

    Lapas, Luciano C; Ferreira, Rogelma M S; Rubí, J Miguel; Oliveira, Fernando A

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  12. Penecontemporaneous metamorphism, fragmentation, and reassembly of ordinary chondrite parent bodies

    NASA Technical Reports Server (NTRS)

    Grimm, R. E.

    1985-01-01

    The thermal histories of ordinary chondrites and the canonical internal heating or onion shell models, which predict an inverse relation between the petrologic type of chondrites and the metallographic cooling rate, are reviewed. The thermal and accretional requirements of the 'metamorphosed planetesimal' model proposed by Scott and Rajan (1981) are analyzed, and an alternative model consistent with the metallographic cooling rate constraints is suggested in which ordinary chondrite parent bodies are collisionally fragmented and then rapidly reassembled before metamorphic heat has been dissipated.

  13. Recent advances in cooled-semen technology.

    PubMed

    Aurich, Christine

    2008-09-01

    The majority of horse registries approve the use of artificial insemination, and horse breeding has widely taken benefit from the use of cooled-stored semen. New insights into cooled-semen technology open possibilities to reduce problems such as impaired semen quality after cooled-storage in individual stallions. The stallion itself has major impacts on quality and fertility of cooled-stored semen. Dietary supplementation of antioxidants and polyunsaturated fatty acids improves semen quality in a variety of species, but only few studies on this topic exist in the horse. Proper semen collection and handling is the main key to the maintenance of semen quality during cooled-storage. Semen collection should be achieved by minimal sexual stimulation with a single mount; this results in high sperm concentration, low content of seminal plasma and minimal contamination with bacteria. Milk-based semen extenders are most popular for semen processing and storage. The development of more defined extenders containing only the beneficial milk ingredients has made extender quality more constant and reliable. Semen is often centrifuged to decrease the seminal plasma content. Centrifugation results in a recovery rate of only 75% of spermatozoa in the semen pellet. Recovery rates after centrifugation may be improved with use of a "cushion technique" allowing higher centrifugation force and duration. However, this is not routinely used in cooled-semen technology. After slow-cooling, semen-storage and shipping is best performed at 5 degrees C, maintaining semen motility, membrane integrity and DNA integrity for up to 40 h after collection. Shipping containers created from Styrofoam boxes provide maintenance of semen quality at low cost.

  14. Comparison of different cooling regimes within a shortened liquid cooling/warming garment on physiological and psychological comfort during exercise

    NASA Technical Reports Server (NTRS)

    Leon, Gloria R.; Koscheyev, Victor S.; Coca, Aitor; List, Nathan

    2004-01-01

    The aim of this study was to compare the effectiveness of different cooling regime intensities to maintain physiological and subjective comfort during physical exertion levels comparable to that engaged in during extravehicular activities (EVA) in space. We studied eight subjects (six males, two females) donned in our newly developed physiologically based shortened liquid cooling/warming garment (SLCWG). Rigorous (condition 1) and mild (condition 2) water temperature cooling regimes were compared at physical exertion levels comparable to that performed during EVA to ascertain the effectiveness of a lesser intensity of cooling in maintaining thermal comfort, thus reducing energy consumption in the portable life support system. Exercise intensity was varied across stages of the session. Finger temperature, rectal temperature, and subjective perception of overall body and hand comfort were assessed. Finger temperature was significantly higher in the rigorous cooling condition and showed a consistent increase across exercise stages, likely due to the restriction of heat extraction because of the intensive cold. In the mild cooling condition, finger temperature exhibited an overall decline with cooling, indicating greater heat extraction from the body. Rectal temperature was not significantly different between conditions, and showed a steady increase over exercise stages in both rigorous and mild cooling conditions. Ratings of overall comfort were 30% higher (more positive) and more stable in mild cooling (p<0.001). The mild cooling regime was more effective than rigorous cooling in allowing the process of heat exchange to occur, thus maintaining thermal homeostasis and subjective comfort during physical exertion.

  15. On carbon monoxide cooling in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Mauas, Pablo J.; Avrett, Eugene H.; Loeser, Rudolf

    1990-01-01

    The CO cooling rate for models of the solar atmosphere using the detailed line-by-line CO opacity in the fundamental band, and carrying out a full radiative transfer calculation for each line is computed. The importance of the different assumptions that have been made to obtain the CO cooling rate and find that when detailed optical depth effects are taken into account, the calculated CO cooling rate at line optical depths near unity can be smaller than optically thin estimates by more than an order of magnitude is studied. It is found that CO cooling does not account for the missing source of radiative cooling in the temperature minimum region of the quiet sun.

  16. A portable personal cooling system for mine rescue operations

    NASA Technical Reports Server (NTRS)

    Webbon, B.; Williams, B.; Kirk, P.; Elkins, W.; Stein, R.

    1977-01-01

    Design of a portable personal cooling system to reduce physiological stress in high-temperature, high-humidity conditions is discussed. The system, based on technology used in the thermal controls of space suits, employs a combination of head and thoracic insulation and cooling through a heat sink unit. Average metabolic rates, heart rates, rectal temperature increase and sweat loss were monitored for test subjects wearing various configurations of the cooling system, as well as for a control group. The various arrangements of the cooling garment were found to provide significant physiological benefits; however, increases in heat transfer rate of the cooling unit and more effective insulation are suggested to improve the system's function.

  17. Turbomachine rotor with improved cooling

    DOEpatents

    Hultgren, Kent Goran; McLaurin, Leroy Dixon; Bertsch, Oran Leroy; Lowe, Perry Eugene

    1998-01-01

    A gas turbine rotor has an essentially closed loop cooling air scheme in which cooling air drawn from the compressor discharge air that is supplied to the combustion chamber is further compressed, cooled, and then directed to the aft end of the turbine rotor. Downstream seal rings attached to the downstream face of each rotor disc direct the cooling air over the downstream disc face, thereby cooling it, and then to cooling air passages formed in the rotating blades. Upstream seal rings attached to the upstream face of each disc direct the heated cooling air away from the blade root while keeping the disc thermally isolated from the heated cooling air. From each upstream seal ring, the heated cooling air flows through passages in the upstream discs and is then combined and returned to the combustion chamber from which it was drawn.

  18. Turbomachine rotor with improved cooling

    DOEpatents

    Hultgren, K.G.; McLaurin, L.D.; Bertsch, O.L.; Lowe, P.E.

    1998-05-26

    A gas turbine rotor has an essentially closed loop cooling air scheme in which cooling air drawn from the compressor discharge air that is supplied to the combustion chamber is further compressed, cooled, and then directed to the aft end of the turbine rotor. Downstream seal rings attached to the downstream face of each rotor disc direct the cooling air over the downstream disc face, thereby cooling it, and then to cooling air passages formed in the rotating blades. Upstream seal rings attached to the upstream face of each disc direct the heated cooling air away from the blade root while keeping the disc thermally isolated from the heated cooling air. From each upstream seal ring, the heated cooling air flows through passages in the upstream discs and is then combined and returned to the combustion chamber from which it was drawn. 5 figs.

  19. Advanced Gas Cooled Nuclear Reactor Materials Evaluation and Development Program. Progress report, January 1, 1980-March 31, 1980

    SciTech Connect

    Not Available

    1980-06-25

    Results are presented of work performed on the Advanced Gas-Cooled Nuclear Reactor Materials Evaluation and Development Program. The objectives of this program are to evaluate candidate alloys for Very High Temperature Reactor (VHTR) Nuclear Process Heat (NPH) and Direct Cycle Helium Turbine (DCHT) applications, in terms of the effect of simulated reactor primary coolant (helium containing small amounts of various other gases), high temperatures, and long time exposures, on the mechanical properties and structural and surface stability of selected candidate alloys. A second objective is to select and recommend materials for future test facilities and more extensive qualification programs. Included are the activities associated with the status of the simulated reactor helium supply system, testing equipment and gas chemistry analysis instrumentation and equipment. The progress in the screening test program is described, including screening creep results and metallographic analysis for materials thermally exposed or tested at 750, 850, and 950/sup 0/C.

  20. Transpiration Cooling Experiment

    NASA Technical Reports Server (NTRS)

    Song, Kyo D.; Ries, Heidi R.; Scotti, Stephen J.; Choi, Sang H.

    1997-01-01

    The transpiration cooling method was considered for a scram-jet engine to accommodate thermally the situation where a very high heat flux (200 Btu/sq. ft sec) from hydrogen fuel combustion process is imposed to the engine walls. In a scram-jet engine, a small portion of hydrogen fuel passes through the porous walls of the engine combustor to cool the engine walls and at the same time the rest passes along combustion chamber walls and is preheated. Such a regenerative system promises simultaneously cooling of engine combustor and preheating the cryogenic fuel. In the experiment, an optical heating method was used to provide a heat flux of 200 Btu/sq. ft sec to the cylindrical surface of a porous stainless steel specimen which carried helium gas. The cooling efficiencies by transpiration were studied for specimens with various porosity. The experiments of various test specimens under high heat flux have revealed a phenomenon that chokes the medium flow when passing through a porous structure. This research includes the analysis of the system and a scaling conversion study that interprets the results from helium into the case when hydrogen medium is used.

  1. Measure Guideline: Ventilation Cooling

    SciTech Connect

    Springer, D.; Dakin, B.; German, A.

    2012-04-01

    The purpose of this measure guideline is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  2. Guide to Cool Roofs

    SciTech Connect

    2011-02-01

    Traditional dark-colored roofing materials absorb sunlight, making them warm in the sun and increasing the need for air conditioning. White or special "cool color" roofs absorb less sunlight, stay cooler in the sun and transmit less heat into the building.

  3. Electron Cooling of RHIC

    SciTech Connect

    I. Ben-Zvi; D.S. Barton; D.B. Beavis; M. Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X.Y. Chang; R. Connolly; Yu.I. Eidelman; A.V. Fedotov; W. Fischer; D.M. Gassner; H. Hahn; M. Harrison; A. Hershcovitch; H.-C. Hseuh; A.K. Jain; P.D.J. Johnson; D. Kayran; J. Kewisch; R.F. Lambiase; V. Litvinenko; W.W. MacKay; G.J. Mahler; N. Malitsky; G.T. McIntyre; W. Meng; K.A.M. Mirabella; C. Montag; T.C.N. Nehring; T. Nicoletti; B. Oerter; G. Parzen; D. Pate; J. Rank; T. Rao; T. Roser; T. Russo; J. Scaduto; K. Smith; D. Trbojevic; G. Wang; J. Wei; N.W.W. Williams; K.-C. Wu; V. Yakimenko; A. Zaltsman; Y. Zhao; D.T. Abell; D.L. Bruhwiler; H. Bluem; A. Burger; M.D. Cole; A.J. Favale; D. Holmes; J. Rathke; T. Schultheiss; A.M.M. Todd; A.V. Burov; S. Nagaitsev; J.R. Delayen; Y.S. Derbenev; L. W. Funk; P. Kneisel; L. Merminga; H.L. Phillips; J.P. Preble; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; J.S. Sekutowicz

    2005-05-16

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

  4. Warm and Cool Cityscapes

    ERIC Educational Resources Information Center

    Jubelirer, Shelly

    2012-01-01

    Painting cityscapes is a great way to teach first-grade students about warm and cool colors. Before the painting begins, the author and her class have an in-depth discussion about big cities and what types of buildings or structures that might be seen in them. They talk about large apartment and condo buildings, skyscrapers, art museums,…

  5. Air-Cooled Turbine Blades with Tip Cap For Improved Leading-Edge Cooling

    NASA Technical Reports Server (NTRS)

    Calvert, Howard F.; Meyer, Andre J., Jr.; Morgan, William C.

    1959-01-01

    An investigation was conducted in a modified turbojet engine to determine the cooling characteristics of the semistrut corrugated air- cooled turbine blade and to compare and evaluate a leading-edge tip cap as a means for improving the leading-edge cooling characteristics of cooled turbine blades. Temperature data were obtained from uncapped air-cooled blades (blade A), cooled blades with the leading-edge tip area capped (blade B), and blades with slanted corrugations in addition to leading-edge tip caps (blade C). All data are for rated engine speed and turbine-inlet temperature (1660 F). A comparison of temperature data from blades A and B showed a leading-edge temperature reduction of about 130 F that could be attributed to the use of tip caps. Even better leading-edge cooling was obtained with blade C. Blade C also operated with the smallest chordwise temperature gradients of the blades tested, but tip-capped blade B operated with the lowest average chordwise temperature. According to a correlation of the experimental data, all three blade types 0 could operate satisfactorily with a turbine-inlet temperature of 2000 F and a coolant flow of 3 percent of engine mass flow or less, with an average chordwise temperature limit of 1400 F. Within the range of coolant flows investigated, however, only blade C could maintain a leading-edge temperature of 1400 F for a turbine-inlet temperature of 2000 F.

  6. Perspectives in microclimate cooling involving protective clothing in hot environments

    SciTech Connect

    Speckman, K.L.; Allan, A.E.; Sawka, M.N.; Young, A.J.; Muza, S.R.

    1987-09-01

    The effectiveness of microclimate cooling systems in alleviating the thermal burden imposed upon soldiers by the wearing of chemical protective clothing under varying environmental conditions was examined in a series of studies conducted by the U.S. Army Research Institute of Environmental Medicine on the copper manikin, in the climatic chambers and in the field. Liquid-cooled undergarments (LCU) and air-cooled vests (ACV) were tested under environmental conditions from 29 C, 85% rh to 52 C, 25% rh. These parameters were chosen to stimulate conditions that may be encountered in either armored vehicles or in desert or tropic climates. The authors reviewed seven studies using LCU (including two ice-cooled vests) and six studies using ACV. LXU tests investigated the effect on cooling when the proportion of total skin surface covered by the LCU was varied. ACV tests examined the effects on cooling during different combinations of air temperature, humidity, and air-flow rates. Additionally, these combinations were tested at low and moderate metabolic rates. The findings from these LCU and ACV studies demonstrate that a) cooling can be increased with a greater body-surface coverage by an LCU, and b) evaporative cooling with an ACV is enhanced at low metabolic rates with optimal combinations of air-flow rates and dry bulb/dew point temperatures, resulting in the extension of tolerance time. The application of these findings to industrial work situations is apparent.

  7. 24 CFR 3280.511 - Comfort cooling certificate and information.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... such air conditioners are rated at 0.3 inch water column static pressure or greater for the cooling air... following shall be supplied in the Comfort Cooling Certificate: Air Conditioner Manufacturer Air Conditioner... Conditioner Manufacturer Certified Capacity ___ BTU/Hr. in accordance with the appropriate Air......

  8. Electron Cooling Study for MEIC

    SciTech Connect

    He, Zhang; Douglas, David R.; Derbenev, Yaroslav S.; Zhang, Yuhong

    2015-09-01

    Electron cooling of the ion beams is one critical R&D to achieve high luminosities in JLab's MEIC proposal. In the present MEIC design, a multi-staged cooling scheme is adapted, which includes DC electron cooling in the booster ring and bunched beam electron cooling in the collider ring at both the injection energy and the collision energy. We explored the feasibility of using both magnetized and non-magnetized electron beam for cooling, and concluded that a magnetized electron beam is necessary. Electron cooling simulation results for the newly updated MEIC design is also presented.

  9. Two-Beam Instability in Electron Cooling

    SciTech Connect

    Burov, Alexey V.; /Fermilab

    2006-04-01

    The drift motion of cooling electrons makes them able to respond to transverse perturbations of a cooled ion beam. This response may lead to dipole or quadrupole transverse instabilities at specific longitudinal wave numbers. While the dipole instabilities can be suppressed by a combination of the Landau damping, machine impedance, and the active damper, the quadrupole and higher order modes can lead to either emittance growth, or a lifetime degradation, or both. The growth rates of these instabilities are strongly determined by the machine x-y coupling. Thus, tuning out of the coupling resonance and/or reduction of the machine coupling can be an efficient remedy for these instabilities.

  10. Estimating total aqueous and airborne chemical emissions from ozonated and chemically treated cooling towers

    SciTech Connect

    Pryor, A.

    1996-10-01

    Cooling tower operations result in aqueous and airborne emissions into the environment in the form of blowdown and drift, respectively. Increased regulatory and licensing requirements often obligate end users to quantify the nature and amount of any added chemicals in such emissions. This paper presents a methodology whereby cooling tower operators can perform such calculations for conventionally chemically treated cooling towers as well as ozonated cooling towers. Emissions from cooling towers depend on the operating characteristics of the tower (recirculation rate, drift rate), makeup and cooling water quality (makeup water mineral concentration, cooling water cycles of concentration), the amount of chemicals added to the cooling water, and/or the amount of ozone injected into the cooling water and the mass transfer efficiency of the ozone injection process.

  11. Laser cooling of a high-temperature oscillator by a three-level system

    NASA Astrophysics Data System (ADS)

    Lau, Hoi-Kwan; Plenio, Martin B.

    2016-08-01

    We study the laser cooling of a mechanical oscillator through the coupling with a dissipative three-level system. Under a background temperature beyond the Lamb-Dicke regime, we extend the standard cooling analysis by separately studying the classical motion and the quantum dynamics of the oscillator. In ladder-system cooling, the cooling rate degrades by orders of magnitude at large classical motion. This phenomenon causes a critical transition of the final temperature at a hot background. In stark contrast, electromagnetic-induced-transparency (EIT) cooling with a Λ system produces significant negative cooling rate at high motional excitation. At steady state, the oscillator could exhibit both cooling and lasing behaviors. We argue that a successful EIT cooling requires either a poor quality oscillator to suppress the lasing effect, or terminating the cooling process at a transient stage.

  12. Analyzing the possibility of achieving more efficient cooling of water in the evaporative cooling towers of the Armenian NPP

    NASA Astrophysics Data System (ADS)

    Petrosyan, V. G.; Yeghoyan, E. A.

    2015-10-01

    The specific features of the service cooling water system used at the Armenian NPP and modifications made in the arrangement for supplying water to the water coolers in order to achieve more efficient cooling are presented. The mathematical model applied in carrying out the analyses is described, the use of which makes it possible to investigate the operation of parallel-connected cooling towers having different hydraulic and thermal loads. When the third standby cooling tower is put into operation (with the same flow rate of water supplied to the water coolers), the cooled water temperature is decreased by around 2-3°C in the range of atmospheric air temperatures 0-35°C. However, the introduced water distribution arrangement with a decreased spraying density has limitation on its use at negative outdoor air temperatures due to the hazard intense freezing of the fill in the cooling tower peripheral zone. The availability of standby cooling towers in the shutdown Armenian NPP power unit along with the planned full replacement of the cooling tower process equipment create good possibilities for achieving a deeper water cooling extent and better efficiency of the NPP. The present work was carried out with the aim of achieving maximally efficient use of existing possibilities and for elaborating the optimal cooling tower modernization version. Individual specific heat-andmass transfer processes in the chimney-type evaporative cooling towers are analyzed. An improved arrangement for distributing cooled water over the cooling tower spraying area (during its operation with a decreased flow rate) is proposed with the aim of cooling water to a deeper extent and preserving the possibility of using the cooling towers in winter. The main idea behind improving the existing arrangement is to exclude certain zones of the cooling tower featuring inefficient cooling from operation. The effectiveness of introducing the proposed design is proven by calculations (taking as an

  13. Heat pipe turbine vane cooling

    SciTech Connect

    Langston, L.; Faghri, A.

    1995-12-31

    The applicability of using heat pipe principles to cool gas turbine vanes is addressed in this beginning program. This innovative concept involves fitting out the vane interior as a heat pipe and extending the vane into an adjacent heat sink, thus transferring the vane incident heat transfer through the heat pipe to heat sink. This design provides an extremely high heat transfer rate and a uniform temperature along the vane due to the internal change of phase of the heat pipe working fluid. Furthermore, this technology can also eliminate hot spots at the vane leading and trailing edges and increase the vane life by preventing thermal fatigue cracking. There is also the possibility of requiring no bleed air from the compressor, and therefore eliminating engine performance losses resulting from the diversion of compressor discharge air. Significant improvement in gas turbine performance can be achieved by using heat pipe technology in place of conventional air cooled vanes. A detailed numerical analysis of a heat pipe vane will be made and an experimental model will be designed in the first year of this new program.

  14. Heat pipe turbine vane cooling

    SciTech Connect

    Langston, L.; Faghri, A.

    1995-10-01

    The applicability of using heat pipe principles to cool gas turbine vanes is addressed in this beginning program. This innovative concept involves fitting out the vane interior as a heat pipe and extending the vane into an adjacent heat sink, thus transferring the vane incident heat transfer through the heat pipe to heat sink. This design provides an extremely high heat transfer rate and an uniform temperature along the vane due to the internal change of phase of the heat pipe working fluid. Furthermore, this technology can also eliminate hot spots at the vane leading and trailing edges and increase the vane life by preventing thermal fatigue cracking. There is also the possibility of requiring no bleed air from the compressor, and therefore eliminating engine performance losses resulting from the diversion of compressor discharge air. Significant improvement in gas turbine performance can be achieved by using heat pipe technology in place of conventional air cooled vanes. A detailed numerical analysis of a heat pipe vane will be made and an experimental model will be designed in the first year of this new program.

  15. Petrographic Evidence for Rapid Heating and Cooling During Chrondrule Formation

    NASA Technical Reports Server (NTRS)

    Wasson, J. T.

    2004-01-01

    The chondrule cooling rates used in most chondrule-formation models appear to be too low. Recent petrographic evidence indicates that the amount of crystal (especially olivine) growth that occurred after the last melting event was about 30 smaller than the grain sizes simulated in order to estimate cooling rates. The smaller amount of growth leads to an upwards revision of cooling rates by about a factor of 1000. Most chondrules are porphyritic. They consist of large and small crystals of olivine and, less commonly, pyroxene immersed in a mesostasis having a plagioclase-rich composition. In the most primitive chondrites the mesostasis is often vitreous. Because the large majority of chondrules contain FeS, it is clear that the nebula had cooled below the FeS condensation temperature (ca. 650 K) before chondrule formation occurred. The high FeO/(FeO+MgO) ratios of some chondrules require still lower nebular temperatures (less than 500 K). The traditional view has been that porphyritic chondrules formed in a single heating/cooling event and many laboratory experiments have been carried out in various kinds of kinds of furnaces to try to simulate the formation of chondrules textures in a single heating/cooling cycle. These furnace experiments have been used to infer the cooling rates of chondrules during the temperature range at which olivine crystallized from the melt. Most of these inferred values are in the range 0.01-1 K per second. These low cooling rates are problematical because there is no long-term nebular environment that yields such values. In transparent regions chondrules would cool at rates orders of magnitude higher, whereas in an opaque nebular disk the cooling rates would be many orders of magnitude lower. And these latter conditions are not suitable locations for chondrule formation because such high temperatures would cause the complete evaporation of chondrules (which have melting temperatures about 600 K higher than their evaporation temperatures

  16. Numerical Analysis of Convection/Transpiration Cooling

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Dilley, Arthur D.; Kelly, H. Neale

    1999-01-01

    An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux, high temperature environment such as hypersonic vehicle engine combustor walls. A boundary layer code and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature. The boundary, layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant. The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

  17. Numerical Analysis of Convection/Transpiration Cooling

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Dilley, Arthur D.; Kelly, H. Neale

    1999-01-01

    An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux high temperature environment such as hypersonic vehicle engine combustor walls. A boundary layer code and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature. The boundary layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant. The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

  18. Does "cooling by heating" protect quantum correlations?

    NASA Astrophysics Data System (ADS)

    Villas-Boas, C. J.; Cardoso, W. B.; Avelar, A. T.; Xuereb, A.; de Almeida, N. G.

    2016-05-01

    The connection between nonequilibrium quantum correlations, such as entanglement and quantum discord, and cooling by heating is investigated for a system composed by two atoms interacting with a single electromagnetic mode of a lossy cavity. This Hamiltonian model is experimentally feasible in the quantum optics domain and presents the occurrence of both nonequilibrium quantum correlations and cooling by heating for a range of parameters. Since in the cooling by heating phenomenon the effective temperature of the system decreases even increasing the environments temperature, it could be expected that quantum correlations could be enhanced. Interestingly, for some parameters we show that, contrary to this expectation, in the case studied here the lowering of the system effective temperature leads to no enhancement in the quantum correlations. In addition, we found that at both zero and finite temperature, depending on the parameters used, quantum correlations can be enhanced even when increasing the damping rates, a somewhat counterintuitive result.

  19. Single Pass Electron Cooling Simulations for MEIC

    SciTech Connect

    Bell, G. I.; Pogorelov, I. V.; Schwartz, B. T.; Zhang, Yuhong; Zhang, He

    2013-12-01

    Cooling of medium energy protons is critical for the proposed Jefferson Lab Medium Energy Ion Collider (MEIC). We present simulations of electron cooling of protons up to 60 GeV. In the beam frame in which the proton and electrons are co-propagating, their motion is non-relativistic. We use a binary collision model which treats the cooling process as the sum of a large number of two-body collisions which are calculated exactly. This model can treat even very close collisions between an electron and ion with high accuracy. We also calculate dynamical friction using a delta-f PIC model. The code VSim (formerly Vorpal) is used to perform the simulations. We compare the friction rates with that obtained by a 3D integral over electron velocities which is used by BETACOOL.

  20. STOCHASTIC COOLING FOR BUNCHED BEAMS.

    SciTech Connect

    BLASKIEWICZ, M.

    2005-05-16

    Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

  1. The Role of the Cooling Prescription for Disk Fragmentation: Numerical Convergence and Critical Cooling Parameter in Self-gravitating Disks

    NASA Astrophysics Data System (ADS)

    Baehr, Hans; Klahr, Hubert

    2015-12-01

    Protoplanetary disks fragment due to gravitational instability when there is enough mass for self-gravitation, described by the Toomre parameter, and when heat can be lost at a rate comparable to the local dynamical timescale, described by {t}{{c}}=β {{{Ω }}}-1. Simulations of self-gravitating disks show that the cooling parameter has a rough critical value at {β }{{crit}}=3. When below {β }{{crit}}, gas overdensities will contract under their own gravity and fragment into bound objects while otherwise maintaining a steady state of gravitoturbulence. However, previous studies of the critical cooling parameter have found dependences on simulation resolution, indicating that the simulation of self-gravitating protoplanetary disks is not so straightforward. In particular, the simplicity of the cooling timescale tc prevents fragments from being disrupted by pressure support as temperatures rise. We alter the cooling law so that the cooling timescale is dependent on local surface density fluctuations, which is a means of incorporating optical depth effects into the local cooling of an object. For lower resolution simulations, this results in a lower critical cooling parameter and a disk that is more stable to gravitational stresses, suggesting that the formation of large gas giants planets in large, cool disks is generally suppressed by more realistic cooling. At our highest resolution, however, the model becomes unstable to fragmentation for cooling timescales up to β =10.

  2. Research on the Compatibility of the Cooling Unit in an Automotive Exhaust-based Thermoelectric Generator and Engine Cooling System

    NASA Astrophysics Data System (ADS)

    Deng, Y. D.; Liu, X.; Chen, S.; Xing, H. B.; Su, C. Q.

    2014-06-01

    The temperature difference between the hot and cold sides of thermoelectric modules is a key factor affecting the conversion efficiency of an automotive exhaust-based thermoelectric generator (TEG). In the work discussed in this paper the compatibility of TEG cooling unit and engine cooling system was studied on the basis of the heat transfer characteristics of the TEG. A new engine-cooling system in which a TEG cooling unit was inserted was simulated at high power and high vehicle speed, and at high power and low vehicle speed, to obtain temperatures and flow rates of critical inlets and outlets. The results show that coolant temperature exceeds its boiling point at high power and low vehicle speed, so the new system cannot meet cooling requirements under these conditions. Measures for improvement to optimize the cooling system are proposed, and provide a basis for future research.

  3. Cooled particle accelerator target

    DOEpatents

    Degtiarenko, Pavel V.

    2005-06-14

    A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

  4. Radial turbine cooling

    NASA Technical Reports Server (NTRS)

    Roelke, Richard J.

    1992-01-01

    Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

  5. Cooling Floor AC Systems

    NASA Astrophysics Data System (ADS)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  6. AIR COOLED NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  7. Water Cooled Mirror Design

    SciTech Connect

    Dale, Gregory E.; Holloway, Michael Andrew; Pulliam, Elias Noel

    2015-03-30

    This design is intended to replace the current mirror setup being used for the NorthStar Moly 99 project in order to monitor the target coupon. The existing setup has limited movement for camera alignment and is difficult to align properly. This proposed conceptual design for a water cooled mirror will allow for greater thermal transfer between the mirror and the water block. It will also improve positioning of the mirror by using flexible vacuum hosing and a ball head joint capable of a wide range of motion. Incorporating this design into the target monitoring system will provide more efficient cooling of the mirror which will improve the amount of diffraction caused by the heating of the mirror. The process of aligning the mirror for accurate position will be greatly improved by increasing the range of motion by offering six degrees of freedom.

  8. A cooling water system copper corrosion study

    SciTech Connect

    Pulkrabek, J.W.

    1998-07-01

    The plant has four units that have been operating normally for 12--33 years. Two of the units are 70 MW sister units that have copper alloy once-through condensers. The other two units are 350 MW and 500 MW units with copper alloy condensers and cooling towers. No cooling water related tube leaks had been experienced. Until 1993, the only chemicals used were sulfuric acid for pH control of the cooling tower systems and chlorine for biological control. The units were chlorinated for one hour per day per condenser. In early July 1992, their copper grab sample at the plant discharge to the river exceeded the weekly environmental limit. In fact, it was so high that there was a slim chance of coming in under their monthly average copper limit unless something was done quickly. The result of this incident was an extensive study of their plant wastewater and cooling systems. The study revealed that the elevated copper problem had existed sporadically for several years. Initially, copper control was achieved by altering the wastewater treatment processes and cooling tower blowdown flow path. Two extended trials, one with tolyltriazole (TTA) and one with a chemically modified benzotriazole (BZT) were performed. Optimal control of copper corrosion was eventually achieved by the application of a TTA treatment program in which the feed rates are adjusted based on on-line corrosion monitoring measurements. This report documents experiences and results over the past six years.

  9. Rapid brain cooling in diving ducks.

    PubMed

    Caputa, M; Folkow, L; Blix, A S

    1998-08-01

    Hypothermia may limit asphyxic damages to the brain, and many small homeotherms have been shown to use anapyrexic strategies when exposed to asphyxic conditions. Larger homeotherms do not seem to use the same strategy, but could save oxygen and prevent hypoxic brain damage by employing selective brain cooling (SBC) in connection with asphyxia. To test the hypothesis that selective brain cooling may take place in connection with asphyxia, we have recorded brain [hypothalamic (THyp)] and body [colonic (TC)] temperatures and heart rates in four Pekin ducks during 5-min simulated (head submersion) diving in cold water (10 degrees C). Diving resulted in a drop in THyp (3.1 +/- 1.4 degrees C) that continued into the recovery period (P < 0.001). Restricting heat loss from the buccal cavity and eyes during diving compromised brain cooling in an additive manner. TC was not influenced by diving. Control cooling of the head with crushed ice during a 5-min period of undisturbed breathing had no effect on THyp. Warm water (35 degrees C) markedly reduced brain cooling, and dive capacity was reduced by approximately 14% (P < 0.05) compared with diving in water at 10 degrees C. The data suggest that SBC is used in ducks during diving, and we propose that this mechanism may enable the bird to save oxygen for prolonged aerobic submergence and to protect the brain from asphyxic damages. PMID:9688670

  10. Finger Cooling During Cold Air Exposure.

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter

    2004-05-01

    This paper presents a method for predicting the onset of finger freezing. It is an extension of a tissue-cooling model originally developed to predict the onset of cheek freezing. The extension to the finger is presented as a more conservative warning of wind chill. Indeed, guidance on the risk of finger freezing is important not only to safeguard the finger, but also because it pertains more closely to susceptible facial features, such as the nose, than if only the risk of cheek freezing was provided. The importance of blood flow to the finger and the modeling of vaso-constriction are demonstrated through cooling predictions that agree reasonably well with several reported observations. Differences in the prediction between the present physiologic-based model and the engineering model used to develop the wind chill index are also discussed. New wind chill charts are presented that tabulate the mean cooling rates and corresponding onset times to freezing of the finger for various combinations of air temperature and wind speed. Results indicate that the surface of the finger cools to its freezing point in approximately one-eighth of the time predicted for the cheek. For combinations that result in the same wind chill temperature (WCT), the rate of finger cooling is faster at the higher wind speed. This asymmetry was previously disclosed through the application of the model to cheek cooling, and it reiterates the ambiguity associated with the reporting of WCT. It is further emphasized that the reporting of onset times to freezing, or safe exposure limits, is a more logical and meaningful alternative to the WCT.

  11. Vaporization Would Cool Primary Battery

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Miyake, Robert N.

    1991-01-01

    Temperature of discharging high-power-density primary battery maintained below specified level by evaporation of suitable liquid from jacket surrounding battery, according to proposal. Pressure-relief valve regulates pressure and boiling temperature of liquid. Less material needed in cooling by vaporization than in cooling by melting. Technique used to cool batteries in situations in which engineering constraints on volume, mass, and location prevent attachment of cooling fins, heat pipes, or like.

  12. Conduction cooled tube supports

    DOEpatents

    Worley, Arthur C.; Becht, IV, Charles

    1984-01-01

    In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

  13. Utility avoids cooling tower

    SciTech Connect

    1994-08-01

    After more than four years of often rancorous debate, New Jersey late last month approved a plan that permits the state`s largest utility to reclaim and restore Delaware Bay marshland instead of constructing a costly cooling tower for two nuclear power units. Environmental interests say they`ll appeal the wetlands proposal, calling it an {open_quotes}unproven experiment{close_quotes} that violates Clean Water Act provisions.

  14. Cooling your home naturally

    SciTech Connect

    1994-10-01

    This fact sheet describes some alternatives to air conditioning which are common sense suggestions and low-cost retrofit options to cool a house. It first describes how to reflect heat away from roofs, walls, and windows. Blocking heat by using insulation or shading are described. The publication then discusses removing built-up heat, reducing heat-generating sources, and saving energy by selecting energy efficient retrofit appliances. A resource list is provided for further information.

  15. Turbine cooling waxy oil

    SciTech Connect

    Geer, J.S.

    1987-10-27

    A process for pipelining a waxy oil to essentially eliminate deposition of wax on the pipeline wall is described comprising: providing a pressurized mixture of the waxy oil and a gas; effecting a sudden pressure drop of the mixture of the oil and the gas through an expansion turbine, thereby expanding the gas and quickly cooling the oil to below its cloud point in the substantial absence of wax deposition and forming a slurry of wax particles and oil; and pipelining the slurry.

  16. Project S'COOL

    NASA Technical Reports Server (NTRS)

    Green, Carolyn J.; Chambers, Lin H.

    1998-01-01

    The Students Clouds Observations On-Line or S'COOL project was piloted in 1997. It was created with the idea of using students to serve as one component of the validation for the Clouds and the Earth's Radiant Energy System (CERES) instrument which was launched with the Tropical Rainfall Measuring Mission (TRMM) in November, 1997. As part of NASA's Earth Science Enterprise CERES is interested in the role clouds play in regulating our climate. Over thirty schools became involved in the initial thrust of the project. The CERES instrument detects the location of clouds and identifies their physical properties. S'COOL students coordinate their ground truth observations with the exact overpass of the satellite at their location. Their findings regarding cloud type, height, fraction and opacity as well as surface conditions are then reported to the NASA Langley Distributed Active Archive Center (DAAC). The data is then accessible to both the CERES team for validation and to schools for educational application via the Internet. By March of 1998 ninety-three schools, in nine countries had enrolled in the S'COOL project. Joining the United States participants were from schools in Australia, Canada, France, Germany, Norway, Spain, Sweden, and Switzerland. The project is gradually becoming the global project envisioned by the project s creators. As students obtain the requested data useful for the scientists, it was hoped that students with guidance from their instructors would have opportunity and motivation to learn more about clouds and atmospheric science as well.

  17. NSCool: Neutron star cooling code

    NASA Astrophysics Data System (ADS)

    Page, Dany

    2016-09-01

    NSCool is a 1D (i.e., spherically symmetric) neutron star cooling code written in Fortran 77. The package also contains a series of EOSs (equation of state) to build stars, a series of pre-built stars, and a TOV (Tolman- Oppenheimer-Volkoff) integrator to build stars from an EOS. It can also handle “strange stars” that have a huge density discontinuity between the quark matter and the covering thin baryonic crust. NSCool solves the heat transport and energy balance equations in whole GR, resulting in a time sequence of temperature profiles (and, in particular, a Teff - age curve). Several heating processes are included, and more can easily be incorporated. In particular it can evolve a star undergoing accretion with the resulting deep crustal heating, under a steady or time-variable accretion rate. NSCool is robust, very fast, and highly modular, making it easy to add new subroutines for new processes.

  18. Ionization cooling and muon dynamics

    SciTech Connect

    Parsa, Z.

    1998-01-01

    Muon colliders potential to provide a probe for fundamental particle physics is very interesting. To obtain the needed collider luminosity, the phase space volume must be greatly reduced within the muon life time. The Ionization cooling is the preferred method used to compress the phase space and reduce the emittance to obtain high luminosity muon beams. The authors note that, the ionization losses results not only in damping, but also heating. They discuss methods used including moments methods, Focker Plank Equation, and Multi Particle Codes. In addition they show how a simple analysis permits us to estimate the most part of the optimal system parameters, such as optimal damping rates, length of the system and energy.

  19. Designing modern furnace cooling systems

    NASA Astrophysics Data System (ADS)

    Merry, J.; Sarvinis, J.; Voermann, N.

    2000-02-01

    An integrated multidisciplinary approach to furnace design that considers the interdependence between furnace cooling elements and other furnace systems, such as binding, cooling water, and instrumentation, is necessary to achieve maximum furnace production and a long refractory life. The retrofit of the BHP Hartley electric furnace and the Kidd Creek copper converting furnace are successful examples of an integrated approach to furnace cooling design.

  20. Water-Cooled Optical Thermometer

    NASA Technical Reports Server (NTRS)

    Menna, A. A.

    1987-01-01

    Water-cooled optical probe measures temperature of nearby radiating object. Intended primarily for use in silicon-growing furnace for measuring and controlling temperatures of silicon ribbon, meniscus, cartridge surfaces, heaters, or other parts. Cooling water and flushing gas cool fiber-optic probe and keep it clean. Fiber passes thermal radiation from observed surface to measuring instrument.

  1. CO2 cooling in terrestrial planet thermospheres

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Hunten, D. M.; Roble, R. G.

    1994-01-01

    We examine the recent progress in the debate on the CO2-O relaxation rate, its temperature dependence, and its corresponding impact on the thermospheric heat budgets of Venus, Earth, and Mars. This comparative approach provides the broadest range of conditions under which a common CO2-O relaxation rate should provide consistent results. New global mean calculations are presented for the heat budgets of these three planets using large CO2-O relaxation rates that have been inferred recently from Earth CO2 radiance measurements and laboratory studies. Results indicate that available Venus and Mars data constrain the CO2-O relaxation rate to be 2-4 x 10(exp -12)/cu cm/s at 300 K. For Venus, this strong cooling serves as an effective thermostat that gives rise to a small variation of thermospheric temperatures over the solar cycle, just as observed. Conversely, CO2 cooling does not appear to be dominant in the dayside heat budget of the Mars thermosphere over most of the solar cycle. For the Earth, this strong cooling implies that the lower thermosphere does not typically require significant eddy diffusion or heat conduction. However, global-scale dynamics or an additional heating mechanism may be needed to restore calculated temperatures to observed values when relaxation rates exceeding 2 x 10(exp -12)/cu cm/s are employed.

  2. Heating and Cooling: Measurement of Temperature for Thermally Connected Systems.

    ERIC Educational Resources Information Center

    Baines, John

    1995-01-01

    Discusses a series of experiments to establish a significance of temperature difference in rates of cooling, to illustrate the connection between energy transfer and the consequent temperature changes for thermally connected systems that are not in equilibrium. (MKR)

  3. Physiologic and Functional Responses of MS Patients to Body Cooling Using Commercially Available Cooling Garments

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Montgomery, Leslie D.; Lee, Hank C.; Luna, Bernadette; Webbon, Bruce W.; Mead, Susan C. (Technical Monitor)

    1999-01-01

    Personal cooling systems are widely used in industrial and aerospace environments to alleviate thermal stress. Increasingly they are also used by heat sensitive multiple sclerosis (HSMS) patients to relieve symptoms and improve quality of life. There are a variety of cooling systems commercially available to the MS community. However, little information is available regarding the comparative physiological changes produced by routine operation of these various systems. The objective of this study was to document and compare the patient response to two passive cooling vests and one active cooling garment. The Life Enhancement Technology, Inc. (LET) lightweight active cooling vest with cap, the MicroClimate Systems (MCS) Change of Phase garment, and the Steele Vest were each used to cool 13 male and 13 female MS subjects (31 to 67 yr.) in this study. The subjects, seated in an upright position at normal room temperature (approximately 22 C), were tested with one of the cooling garments. Oral, fight and left ear temperatures were logged manually every 5 min. An-n, leg, chest and rectal temperatures; heart rate; and respiration were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. Each subject was given a series of subjective and objective evaluation tests before and after cooling. The LET and Steele vests test groups had similar, significant (P less than 0.01) cooling effects on oral and ear canal temperature, which decreased approximately 0.4 C, and 0.3 C, respectively. Core temperature increased (N.S.) with all three vests during cooling. The LET vest produced the coldest (P less than 0.01) skin temperature. Overall, the LET vest provided the most improvement on subjective and objective performance measures. These results show that the garment configurations tested do not elicit a similar thermal response in all MS patients. Cooling with the LET active garment configuration resulted in the lowest body temperatures for the MS subjects; cooling with

  4. Ultraefficient Cooling of Resonators: Beating Sideband Cooling with Quantum Control

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoting; Vinjanampathy, Sai; Strauch, Frederick; Jacobs, Kurt

    2012-02-01

    There is presently a great deal of interest in cooling high-frequency micro- and nano-mechanical oscillators to their ground states. The present state of the art in cooling mechanical resonators is a version of sideband cooling, which was originally developed in the context of cooling trapped ions. Here we present a method based on quantum control that uses the same configuration as sideband cooling--coupling the resonator to be cooled to a second microwave (or optical) auxiliary resonator--but will cool significantly colder. This is achieved by applying optimal control and varying the strength of the coupling between the two resonators over a time on the order of the period of the mechanical resonator. As part of our analysis, we also obtain a method for fast, high-fidelity quantum information transfer between resonators.

  5. Consideration of wear rates at high velocity

    NASA Astrophysics Data System (ADS)

    Hale, Chad S.

    The development of the research presented here is one in which high velocity relative sliding motion between two bodies in contact has been considered. Overall, the wear environment is truly three-dimensional. The attempt to characterize three-dimensional wear was not economically feasible because it must be analyzed at the micro-mechanical level to get results. Thus, an engineering approximation was carried out. This approximation was based on a metallographic study identifying the need to include viscoplasticity constitutive material models, coefficient of friction, relationships between the normal load and velocity, and the need to understand wave propagation. A sled test run at the Holloman High Speed Test Track (HHSTT) was considered for the determination of high velocity wear rates. In order to adequately characterize high velocity wear, it was necessary to formulate a numerical model that contained all of the physical events present. The experimental results of a VascoMax 300 maraging steel slipper sliding on an AISI 1080 steel rail during a January 2008 sled test mission were analyzed. During this rocket sled test, the slipper traveled 5,816 meters in 8.14 seconds and reached a maximum velocity of 1,530 m/s. This type of environment was never considered previously in terms of wear evaluation. Each of the features of the metallography were obtained through micro-mechanical experimental techniques. The byproduct of this analysis is that it is now possible to formulate a model that contains viscoplasticity, asperity collisions, temperature and frictional features. Based on the observations of the metallographic analysis, these necessary features have been included in the numerical model, which makes use of a time-dynamic program which follows the movement of a slipper during its experimental test run. The resulting velocity and pressure functions of time have been implemented in the explicit finite element code, ABAQUS. Two-dimensional, plane strain models

  6. Extending the life of water-cooled copper cooling fingers for furnace refractories

    NASA Astrophysics Data System (ADS)

    Plascencia, Gabriel; Utigard, Torstein A.; Plascencia, Gabriel; Jaramillo, David

    2005-10-01

    To extend the service life of refractory linings in high-temperature furnaces, it is becoming common to embed copper cooling devices in the lining. These devices extract enough heat from the hearth of the furnace to freeze a protective thin layer of slag onto the surface of the lining. However, the cooling devices may lose their efficiency over time. It is believed that high-temperature oxidation of copper is responsible for the loss in heat-extraction capacity. To test coolers under severe conditions, immersion tests were carried out in molten matte and slag of laboratory-scale cooling elements protected by various means. A composite cooler was developed that consists of a copper core shielded by a Cu-4 wt.% Al alloy sheet. Although the rate of heat extraction is not as high as that of the un-alloyed copper, this cooler still extracts heat at a very high rate.

  7. Electron cooling of electron beams

    SciTech Connect

    Larson, D.J.

    1993-09-01

    Electron cooling of electron (and positron) sources may be important for future linear collider applications. In order to cool electrons with electrons, an intermediary positron beam must be employed, since it is impossible to merge two beams of identical particles into the cooling straight. By adjusting the beta functions of the electron and positron lattices appropriately, the final emittance of the stored electron beam can be made less than the emittance of the cooling electron beam. This paper will discuss accelerator physics issues relating to an electron-cooled electron beam source.

  8. Facial Cooling During Cold Air Exposure.

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter; Osczevski, Randall J.

    2003-07-01

    A dynamic model of facial cooling was developed in conjunction with the release of the new wind chill temperature (WCT) index, whereby the WCT provides wind chill estimates based on steady-state considerations and the dynamic model can be used to predict the rate of facial cooling and particularly the onset of freezing. In the present study, the dynamic model is applied to various combinations of air temperature and wind speed, and predictions of the resultant steady-state cheek skin temperatures are tabulated. Superimposed on these tables are times to a cheek skin temperature of 10°C, which has been reported as painful, and times to freezing. For combinations of air temperature and wind speed that result in the same final steady-state cheek temperature or the same WCT, the initial rate of change of skin temperature is higher for those combinations having higher wind speeds. This suggests that during short exposures, high winds combined with low temperatures might be perceived as more stressful than light winds with lower temperatures that result in the same "wind chill." This paper also discloses the paradox that individuals having a low cheek thermal resistance are predicted to experience a more severe WCT, but be at less risk of cooling injury than individuals with higher thermal resistances. The advantages of cooling-time predictions using the dynamic model are discussed with the recommendation/conclusion that safe exposure limits are more meaningful and less ambiguous than the reporting of the WCT.

  9. Mapping Variations in Ring Shadow Cooling with Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Brooks, S. M.; Spilker, L. J.; Morishima, R.; Pilorz, S.

    2011-12-01

    We use data from Cassini's Composite Infrared Spectrometer to characterize ring shadow cooling and to document radial variations in ring thermal inertia. CIRS records infrared radiation between 7 and 1000 microns. Far infrared radiation (16.7 - 1000 microns) is recorded at focal plane 1 (FP1). Thermal emission from Saturn's rings peaks at FP1 wavelengths. As shown in Spilker et al. (2005, 2006), ring thermal emission is well characterized as blackbody emission multiplied by a scalar factor related to the emissivity of the rings. Ring temperatures are generally warmer and the rings show significantly more thermal contrast at larger solar elevations. The thermal budget of the rings is dominated by incident solar radiation. When ring particles enter Saturn's shadow this source of energy is abruptly cut off with a consequential decrease in ring temperature. In order to quantify this cooling, FP1 scanned the main rings repeatedly with a constant offset from the ingress shadow boundary. From such shadow observations we create cooling curves at specific locations. By resampling the FP1 scans onto a consistent radial grid, we can document the cooling of the ensemble of ring particles as they enter Saturn's shadow. Observations of the lit side of the rings reveal that shadow cooling is most significant in the C ring and Cassini Division. More modest cooling occurs in the B and A rings. More importantly, we can show that cooling rates vary with location within each ring. These cooling rates reflect local reactions to the short-term change in thermal forcing as the ring particles enter Saturn's shadow. Observations of the unlit side of the rings tell a different tale. The optically thin rings show some shadow cooling, but this cooling is not as pronounced as on the lit side. No evidence for shadow cooling exists for the unlit A and B rings. Temperature variations on the unlit sides of these optically thick rings appear to reflect thermal forcings that vary with Saturn season

  10. Multilayer composite material and method for evaporative cooling

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2002-01-01

    A multilayer composite material and method for evaporative cooling of a person employs an evaporative cooling liquid that changes phase from a liquid to a gaseous state to absorb thermal energy. The evaporative cooling liquid is absorbed into a superabsorbent material enclosed within the multilayer composite material. The multilayer composite material has a high percentage of the evaporative cooling liquid in the matrix. The cooling effect can be sustained for an extended period of time because of the high percentage of phase change liquid that can be absorbed into the superabsorbent. Such a composite can be used for cooling febrile patients by evaporative cooling as the evaporative cooling liquid in the matrix changes from a liquid to a gaseous state to absorb thermal energy. The composite can be made with a perforated barrier material around the outside to regulate the evaporation rate of the phase change liquid. Alternatively, the composite can be made with an imperveous barrier material or semipermeable membrane on one side to prevent the liquid from contacting the person's skin. The evaporative cooling liquid in the matrix can be recharged by soaking the material in the liquid. The multilayer composite material can be fashioned into blankets, garments and other articles.

  11. A hemolysis study of an intravascular blood cooling system for localized organ tissue cooling.

    PubMed

    Merrill, T L; Mingin, T; Merrill, D R; Botbyl, J; Akers, J E

    2013-01-01

    Therapeutic hypothermia can reduce both ischemic and reperfusion injury arising after strokes and heart attacks. New localized organ cooling systems offer a way to reduce tissue damage more effectively with fewer side effects. To assess initial blood safety of our new organ cooling system, the CoolGuide Cooling System (CCS), we investigated safe operating conditions and configurations from a hemolysis perspective. The CCS consists of a peristaltic pump, a custom-built external heat exchanger, a chiller, biocompatible polyvinyl cellulose (PVC) tubing, and a control console. The CCS cools and circulates autologous blood externally and re-delivers cooled blood to the patient through a conventional catheter inserted directly into the organ at risk. Catheter configurations used included: a 7F guide catheter only, a 7F guide with a 0.038" wire inserted through the center and advanced 2 cm distal to the catheter distal tip, a 6F guide catheter only and a 6F guide with a 0.014" guidewire similarly inserted through the center. Using porcine blood, an in vitro test rig was used to measure the degree of hemolysis generation, defined as the percentage change in free hemoglobin, adjusted for total hemoglobin and hematocrit, between exiting and entering blood. The highest degree of hemolysis generation was 0.11±0.04%, based on the average behavior with a 6F catheter and a 0.014" guidewire configuration at a blood flow rate of approximately 130 mL/min. In terms of average percentage free hemoglobin exiting the system, based on total hemoglobin, the highest value measured was 0.17%±0.03%, using this 6F and 0.014" guidewire configuration. This result is significantly below the most stringent European guideline of 0.8% used for blood storage and transfusion. This study provides initial evidence showing hemolysis generation arising from the CoolGuide Cooling System is likely to be clinically insignificant. PMID:23047283

  12. New conceptual method for directly cooling the target biological tissues

    NASA Astrophysics Data System (ADS)

    Ji, Yan; Liu, Jing

    2005-01-01

    Hypothermia is a commonly adopted strategy to decrease the cerebral oxygen demands, which is critical for the patient to sustain longer time when subjected to a hypoxia. However, when circulatory arrest occurs, the traditional approaches such as selective brain cooling (SBC), systemic body cooling or perfusing cool blood are often not very helpful due to their slow cooling rates in preventing the tendency of a slight cerebral temperature increase at the onset of circulatory arrest. To resolve such difficult issue, a new conceptual volumetric cooling method (VCM) through minimally invasive injection of physiological coolant was proposed in this study. A heat and fluid transport model based on porous medium configuration was established to describe the thermal responses of brain tissues during hypothermia resuscitation. Theoretical calculations indicated that VCM could significantly improve the cooling rate in the deep part of the biological tissues within a desired period of time. To further test this approach, a series of either in vitro or in vivo animal experiments were performed, which also strongly supported the theoretical predictions and indicated that VCM was well appropriate for the localized cooling of target tissues. The concept of the present VCM could also possibly be extended to more wide clinical situations, when an instant and highly localized cooling for the specific organs or tissues are urgently requested. It also raised challenging issues such as injury or negative effect for the clinical operation of this VCM, which need to be addressed in the coming study.

  13. Evaporative cooling for Holstein dairy cows under grazing conditions

    NASA Astrophysics Data System (ADS)

    Valtorta, Silvia E.; Gallardo, Miriam R.

    . Twenty-four grazing Holstein cows in mid and late lactation were randomly assigned to two treatment groups: control and cooled. The trial was performed at the Experimental Dairy Unit, Rafaela Agricultural Experimental Station (INTA), Argentina. The objective was to evaluate the effects of sprinkler and fan cooling before milkings on milk production and composition. The effects of the cooling system on rectal temperature and respiration rate were also evaluated. Cooled cows showed higher milk production (1.04 l cow-1 day-1). The concentration and yield of milk fat and protein increased in response to cooling treatment. The cooling system also reduced rectal temperature and respiration rate. No effects were observed on body condition. It was concluded that evaporative cooling, which is efficient for housed animals, is also appropriate to improve yields and animal well-being under grazing systems. These results are impressive since the cooling system was utilized only before milkings, in a system where environmental control is very difficult to achieve. This trial was performed during a mild summer. The results would probably be magnified during hotter weather.

  14. Wissler Simulations of a Liquid Cooled and Ventilation Garment (LCVG) for Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    Kesterson, Matthew; Bue, Grant; Trevino, Luis

    2006-01-01

    In order to provide effective cooling for astronauts during extravehicular activities (EVAs), a liquid cooling and ventilation garment (LCVG) is used to remove heat by a series off tubes through which cooling water is circulated. To better predict the effectiveness of the LCG and determine possible modifications to improve performance, computer simulations dealing with the interaction of the cooling garment with the human body have been run using the Wissler Human Model. Simulations have been conducted to predict the heat removal rate for various liquid cooled garment configurations. The current LCVG uses 48 cooling tubes woven into a fabric with cooling water flowing through the tubes. The purpose of the current project is to decrease the overall weight of the LCVG system. In order to achieve this weight reduction, advances in the garment heat removal rates need to be obtained. Currently, increasing the fabric s thermal conductivity along with also examining an increase in the cooling tube conductivity to more efficiently remove the excess heat generated during EVA is being simulated. Initial trials varied cooling water temperature, water flow rate, garment conductivity, tube conductivity, and total number of cooling tubes in the LCVG. Results indicate that the total number of cooling tubes could be reduced to 22 and still achieve the desired heat removal rate of 361 W. Further improvements are being made to the garment network used in the model to account for temperature gradients associated with the spacing of the cooling tubes over the surface of the garment

  15. 16 CFR Appendix H to Part 305 - Cooling Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... for Central Air Conditioners Manufacturer's rated cooling capacities (Btu's/hr.) Range of SEER's Low High Single Package Units Central Air Conditioners (Cooling Only): All capacities 10.6 16.5 Heat Pumps...): All capacities 10.9 23.0 Heat Pumps (Cooling Function): All capacities 10.9 21.0...

  16. Modeling active galactic nucleus feedback in cool-core clusters: The balance between heating and cooling

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-01

    We study the long-term evolution of an idealized cool-core galaxy cluster under the influence of momentum-driven active galactic nucleus (AGN) feedback using three-dimensional high-resolution (60 pc) adaptive mesh refinement simulations. The feedback is modeled with a pair of precessing jets whose power is calculated based on the accretion rate of the cold gas surrounding the supermassive black hole (SMBH). The intracluster medium first cools into clumps along the propagation direction of the jets. As the jet power increases, gas condensation occurs isotropically, forming spatially extended structures that resemble the observed Hα filaments in Perseus and many other cool-core clusters. Jet heating elevates the gas entropy, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk of ∼10{sup 11} M {sub ☉}. The hot gas cools directly onto the disk while the SMBH accretes from its innermost region, powering the AGN that maintains a thermally balanced state for a few Gyr. The mass cooling rate averaged over 7 Gyr is ∼30 M {sub ☉} yr{sup –1}, an order of magnitude lower than the classic cooling flow value. Medium resolution simulations produce similar results, while in low resolution runs, the cluster experiences cycles of gas condensation and AGN outbursts. Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Our model also produces cold structures in early stages that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed.

  17. Rotary engine cooling system

    NASA Technical Reports Server (NTRS)

    Jones, Charles (Inventor); Gigon, Richard M. (Inventor); Blum, Edward J. (Inventor)

    1985-01-01

    A rotary engine has a substantially trochoidal-shaped housing cavity in which a rotor planetates. A cooling system for the engine directs coolant along a single series path consisting of series connected groups of passages. Coolant enters near the intake port, passes downwardly and axially through the cooler regions of the engine, then passes upwardly and axially through the hotter regions. By first flowing through the coolest regions, coolant pressure is reduced, thus reducing the saturation temperature of the coolant and thereby enhancing the nucleate boiling heat transfer mechanism which predominates in the high heat flux region of the engine during high power level operation.

  18. Cooled artery extension

    NASA Technical Reports Server (NTRS)

    Gernert, Nelson J. (Inventor)

    1990-01-01

    An artery vapor trap. A heat pipe artery is constructed with an extension protruding from the evaporator end of the heat pipe beyond the active area of the evaporator. The vapor migrates into the artery extension because of gravity or liquid displacement, and cooling the extension condenses the vapor to liquid, thus preventing vapor lock in the working portion of the artery by removing vapor from within the active artery. The condensed liquid is then transported back to the evaporator by the capillary action of the artery extension itself or by wick located within the extension.

  19. Cooling apparatus and method

    DOEpatents

    Mayes, James C.

    2009-05-05

    A device and method provide for cooling of a system having an energy source, one or more devices that actively consume energy, and one or more devices that generate heat. The device may include one or more thermoelectric coolers ("TECs") in conductive engagement with at least one of the heat-generating devices, and an energy diverter for diverting at least a portion of the energy from the energy source that is not consumed by the active energy-consuming devices to the TECs.

  20. Cooled, temperature controlled electrometer

    DOEpatents

    Morgan, John P.

    1992-08-04

    A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

  1. Cooled, temperature controlled electrometer

    DOEpatents

    Morgan, John P.

    1992-01-01

    A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

  2. Superconducting magnet cooling system

    DOEpatents

    Vander Arend, Peter C.; Fowler, William B.

    1977-01-01

    A device is provided for cooling a conductor to the superconducting state. The conductor is positioned within an inner conduit through which is flowing a supercooled liquid coolant in physical contact with the conductor. The inner conduit is positioned within an outer conduit so that an annular open space is formed therebetween. Through the annular space is flowing coolant in the boiling liquid state. Heat generated by the conductor is transferred by convection within the supercooled liquid coolant to the inner wall of the inner conduit and then is removed by the boiling liquid coolant, making the heat removal from the conductor relatively independent of conductor length.

  3. COOLED NEUTRONIC REACTOR

    DOEpatents

    Binner, C.R.; Wilkie, C.B.

    1958-03-18

    This patent relates to a design for a reactor of the type in which a fluid coolant is flowed through the active portion of the reactor. This design provides for the cooling of the shielding material as well as the reactor core by the same fluid coolant. The core structure is a solid moderator having coolant channels in which are disposed the fuel elements in rod or slug form. The coolant fluid enters the chamber in the shield, in which the core is located, passes over the inner surface of said chamber, enters the core structure at the center, passes through the coolant channels over the fuel elements and out through exhaust ducts.

  4. Cooled infrared telescope development

    NASA Technical Reports Server (NTRS)

    Young, L. S.

    1976-01-01

    The feasibility of the design concept for a 1-m-aperture, cryogenically cooled telescope for Spacelab is assessed. The device makes use of double-folded Gregorian reflective optics. The planned cryogen is helium, and beryllium will be used for the 1.2 m primary mirror. Results of studies based on smaller instruments indicate that no new technology will be required to construct a Shuttle Infrared Telescope Facility which will offer improvement over the sensitivity of conventional telescopes by a factor of 1000 at 10 micrometers.

  5. Solar space heating and cooling by selective use of the components of a desiccant cooling system

    NASA Astrophysics Data System (ADS)

    Abbud, Ihsan Aladdin

    , the thermal energy needed for desiccant cooling is three to four times greater than that for Los Angeles and New York, so the desiccant system is not a competitive option in hot, humid climates. Life cycle savings in the three locations show that operation of the desiccant cooling and heating system with solar energy is more costly than with conventional energy at 1996 prices. Solar energy would become competitive, however, if annual electric energy inflation rates exceed 10 percent.

  6. Evaporative cooling of speleothem drip water

    NASA Astrophysics Data System (ADS)

    Cuthbert, M. O.; Rau, G. C.; Andersen, M. S.; Roshan, H.; Rutlidge, H.; Marjo, C. E.; Markowska, M.; Jex, C. N.; Graham, P. W.; Mariethoz, G.; Acworth, R. I.; Baker, A.

    2014-06-01

    This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ18O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change.

  7. Evaporative cooling of speleothem drip water

    PubMed Central

    Cuthbert, M. O.; Rau, G. C.; Andersen, M. S.; Roshan, H.; Rutlidge, H.; Marjo, C. E.; Markowska, M.; Jex, C. N.; Graham, P. W.; Mariethoz, G.; Acworth, R. I.; Baker, A.

    2014-01-01

    This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ18O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change. PMID:24895139

  8. Cooled spool piston compressor

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  9. Beverage dispenser cooling system

    SciTech Connect

    Stanfill, T.M.

    1988-03-15

    In a beverage dispensing system of the type having a supply container of the beverage located at a storage site, valve means at a dispensing site remote from the storage site for dispensing the beverage, pressure means for supplying the beverage under pressure from the supply container to the valve means through a beverage conduit, refrigeration means at the storage site for cooling a liquid into a chilled liquid, pump means at the storage site for circulating the chilled liquid from the storage site to the dispensing site through a transmit chilled line and from the dispensing sites back to the storage site through a return chilled line, the chilled lines running in parallel with the beverage conduit within an insulated jacket conduit extending between the storage and dispensing site, the improvement is described comprising in combination: an insulated concentric section located at the dispensing site, having an inner conduit concentrically located within an outer conduit; and manifold means for connecting the transmit and return chilled lines to opposite ends of one of the concentric conduits, and for connecting the beverage conduit and valve means to opposite ends of the other concentric conduit, to further cool the beverage by heat transfer from the chilled liquid in the concentric section.

  10. Emergency core cooling system

    DOEpatents

    Schenewerk, William E.; Glasgow, Lyle E.

    1983-01-01

    A liquid metal cooled fast breeder reactor provided with an emergency core cooling system includes a reactor vessel which contains a reactor core comprising an array of fuel assemblies and a plurality of blanket assemblies. The reactor core is immersed in a pool of liquid metal coolant. The reactor also includes a primary coolant system comprising a pump and conduits for circulating liquid metal coolant to the reactor core and through the fuel and blanket assemblies of the core. A converging-diverging venturi nozzle with an intermediate throat section is provided in between the assemblies and the pump. The intermediate throat section of the nozzle is provided with at least one opening which is in fluid communication with the pool of liquid sodium. In normal operation, coolant flows from the pump through the nozzle to the assemblies with very little fluid flowing through the opening in the throat. However, when the pump is not running, residual heat in the core causes fluid from the pool to flow through the opening in the throat of the nozzle and outwardly through the nozzle to the assemblies, thus providing a means of removing decay heat.

  11. ASTROMAG coil cooling study

    NASA Technical Reports Server (NTRS)

    Maytal, Ben-Zion; Vansciver, Steven W.

    1990-01-01

    ASTROMAG is a planned particle astrophysics magnetic facility. Basically it is a large magnetic spectrometer outside the Earth's atmosphere for an extended period of time in orbit on a space station. A definition team summarized its scientific objectives assumably related to fundamental questions of astrophysics, cosmology, and elementary particle physics. Since magnetic induction of about 7 Tesla is desired, it is planned to be a superconducting magnet cooled to liquid helium 2 temperatures. The general structure of ASTROMAG is based on: (1) two superconducting magnetic coils, (2) dewar of liquid helium 2 to provide cooling capability for the magnets; (3) instrumentation, matter-anti matter spectrometer (MAS) and cosmic ray isotope spectrometer (CRIS); and (4) interfaces to the shuttle and space station. Many configurations of the superconducting magnets and the dewar were proposed and evaluated, since those are the heart of the ASTROMAG. Baseline of the magnet configuration and cryostat as presented in the phase A study and the one kept in mind while doing the present study are presented. ASTROMAG's development schedule reflects the plan of launching to the space station in 1995.

  12. NightCool: A Nocturnal Radiation Cooling Concept

    SciTech Connect

    Parker, Danny S.; Sherwin, John R.; Hermelink, Andreas H.

    2008-08-26

    This report describes an experimental evaluation that was conducted on a night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling - largely during nighttime hours.

  13. A model for radionuclide transport in the Cooling Water System

    SciTech Connect

    Kahook, S.D.

    1992-08-01

    A radionuclide transport model developed to assess radiological levels in the K-reactor Cooling Water System (CWS) in the event of an inadvertent process water (PW) leakage to the cooling water (CW) in the heat exchangers (HX) is described. During and following a process water leak, the radionuclide transport model determines the time-dependent release rates of radionuclide from the cooling water system to the environment via evaporation to the atmosphere and blow-down to the Savannah River. The developed model allows for delay times associated with the transport of the cooling water radioactivity through cooling water system components. Additionally, this model simulates the time-dependent behavior of radionuclides levels in various CWS components. The developed model is incorporated into the K-reactor Cooling Tower Activity (KCTA) code. KCTA allows the accident (heat exchanger leak rate) and the cooling tower blow-down and evaporation rates to be described as time-dependent functions. Thus, the postulated leak and the consequence of the assumed leak can be modelled realistically. This model is the first of three models to be ultimately assembled to form a comprehensive Liquid Pathway Activity System (LPAS). LPAS will offer integrated formation, transport, deposition, and release estimates for radionuclides formed in a SRS facility. Process water and river water modules are forthcoming as input and downstream components, respectively, for KCTA.

  14. Method of Estimating Continuous Cooling Transformation Curves of Glasses

    NASA Technical Reports Server (NTRS)

    Zhu, Dongmei; Zhou, Wancheng; Ray, Chandra S.; Day, Delbert E.

    2006-01-01

    A method is proposed for estimating the critical cooling rate and continuous cooling transformation (CCT) curve from isothermal TTT data of glasses. The critical cooling rates and CCT curves for a group of lithium disilicate glasses containing different amounts of Pt as nucleating agent estimated through this method are compared with the experimentally measured values. By analysis of the experimental and calculated data of the lithium disilicate glasses, a simple relationship between the crystallized amount in the glasses during continuous cooling, X, and the temperature of undercooling, (Delta)T, was found to be X = AR(sup-4)exp(B (Delta)T), where (Delta)T is the temperature difference between the theoretical melting point of the glass composition and the temperature in discussion, R is the cooling rate, and A and B are constants. The relation between the amount of crystallisation during continuous cooling and isothermal hold can be expressed as (X(sub cT)/X(sub iT) = (4/B)(sup 4) (Delta)T(sup -4), where X(sub cT) stands for the crystallised amount in a glass during continuous cooling for a time t when the temperature comes to T, and X(sub iT) is the crystallised amount during isothermal hold at temperature T for a time t.

  15. Simultaneous Synchrotron WAXD and Fast Scanning (Chip) Calorimetry: On the (Isothermal) Crystallization of HDPE and PA11 at High Supercoolings and Cooling Rates up to 200 °C s(-1).

    PubMed

    Baeten, Dorien; Mathot, Vincent B F; Pijpers, Thijs F J; Verkinderen, Olivier; Portale, Giuseppe; Van Puyvelde, Peter; Goderis, Bart

    2015-06-01

    An experimental setup, making use of a Flash DSC 1 prototype, is presented in which materials can be studied simultaneously by fast scanning calorimetry (FSC) and synchrotron wide angle X-ray diffraction (WAXD). Accumulation of multiple, identical measurements results in high quality, millisecond WAXD patterns. Patterns at every degree during the crystallization and melting of high density polyethylene at FSC typical scanning rates from 20 up to 200 °C s(-1) are discussed in terms of the temperature and scanning rate dependent material crystallinities and crystal densities. Interestingly, the combined approach reveals FSC thermal lag issues, for which can be corrected. For polyamide 11, isothermal solidification at high supercooling yields a mesomorphic phase in less than a second, whereas at very low supercooling crystals are obtained. At intermediate supercooling, mixtures of mesomorphic and crystalline material are generated at a ratio proportional to the supercooling. This ratio is constant over the isothermal solidification time. PMID:25845310

  16. Simultaneous Synchrotron WAXD and Fast Scanning (Chip) Calorimetry: On the (Isothermal) Crystallization of HDPE and PA11 at High Supercoolings and Cooling Rates up to 200 °C s(-1).

    PubMed

    Baeten, Dorien; Mathot, Vincent B F; Pijpers, Thijs F J; Verkinderen, Olivier; Portale, Giuseppe; Van Puyvelde, Peter; Goderis, Bart

    2015-06-01

    An experimental setup, making use of a Flash DSC 1 prototype, is presented in which materials can be studied simultaneously by fast scanning calorimetry (FSC) and synchrotron wide angle X-ray diffraction (WAXD). Accumulation of multiple, identical measurements results in high quality, millisecond WAXD patterns. Patterns at every degree during the crystallization and melting of high density polyethylene at FSC typical scanning rates from 20 up to 200 °C s(-1) are discussed in terms of the temperature and scanning rate dependent material crystallinities and crystal densities. Interestingly, the combined approach reveals FSC thermal lag issues, for which can be corrected. For polyamide 11, isothermal solidification at high supercooling yields a mesomorphic phase in less than a second, whereas at very low supercooling crystals are obtained. At intermediate supercooling, mixtures of mesomorphic and crystalline material are generated at a ratio proportional to the supercooling. This ratio is constant over the isothermal solidification time.

  17. Quantitative data analysis to determine best food cooling practices in U.S. restaurants.

    PubMed

    Schaffner, Donald W; Brown, Laura Green; Ripley, Danny; Reimann, Dave; Koktavy, Nicole; Blade, Henry; Nicholas, David

    2015-04-01

    Data collected by the Centers for Disease Control and Prevention (CDC) show that improper cooling practices contributed to more than 500 foodborne illness outbreaks associated with restaurants or delis in the United States between 1998 and 2008. CDC's Environmental Health Specialists Network (EHS-Net) personnel collected data in approximately 50 randomly selected restaurants in nine EHS-Net sites in 2009 to 2010 and measured the temperatures of cooling food at the beginning and the end of the observation period. Those beginning and ending points were used to estimate cooling rates. The most common cooling method was refrigeration, used in 48% of cooling steps. Other cooling methods included ice baths (19%), room-temperature cooling (17%), ice-wand cooling (7%), and adding ice or frozen food to the cooling food as an ingredient (2%). Sixty-five percent of cooling observations had an estimated cooling rate that was compliant with the 2009 Food and Drug Administration Food Code guideline (cooling to 41 °F [5 °C] in 6 h). Large cuts of meat and stews had the slowest overall estimated cooling rate, approximately equal to that specified in the Food Code guideline. Pasta and noodles were the fastest cooling foods, with a cooling time of just over 2 h. Foods not being actively monitored by food workers were more than twice as likely to cool more slowly than recommended in the Food Code guideline. Food stored at a depth greater than 7.6 cm (3 in.) was twice as likely to cool more slowly than specified in the Food Code guideline. Unventilated cooling foods were almost twice as likely to cool more slowly than specified in the Food Code guideline. Our data suggest that several best cooling practices can contribute to a proper cooling process. Inspectors unable to assess the full cooling process should consider assessing specific cooling practices as an alternative. Future research could validate our estimation method and study the effect of specific practices on the full

  18. Quantitative data analysis to determine best food cooling practices in U.S. restaurants.

    PubMed

    Schaffner, Donald W; Brown, Laura Green; Ripley, Danny; Reimann, Dave; Koktavy, Nicole; Blade, Henry; Nicholas, David

    2015-04-01

    Data collected by the Centers for Disease Control and Prevention (CDC) show that improper cooling practices contributed to more than 500 foodborne illness outbreaks associated with restaurants or delis in the United States between 1998 and 2008. CDC's Environmental Health Specialists Network (EHS-Net) personnel collected data in approximately 50 randomly selected restaurants in nine EHS-Net sites in 2009 to 2010 and measured the temperatures of cooling food at the beginning and the end of the observation period. Those beginning and ending points were used to estimate cooling rates. The most common cooling method was refrigeration, used in 48% of cooling steps. Other cooling methods included ice baths (19%), room-temperature cooling (17%), ice-wand cooling (7%), and adding ice or frozen food to the cooling food as an ingredient (2%). Sixty-five percent of cooling observations had an estimated cooling rate that was compliant with the 2009 Food and Drug Administration Food Code guideline (cooling to 41 °F [5 °C] in 6 h). Large cuts of meat and stews had the slowest overall estimated cooling rate, approximately equal to that specified in the Food Code guideline. Pasta and noodles were the fastest cooling foods, with a cooling time of just over 2 h. Foods not being actively monitored by food workers were more than twice as likely to cool more slowly than recommended in the Food Code guideline. Food stored at a depth greater than 7.6 cm (3 in.) was twice as likely to cool more slowly than specified in the Food Code guideline. Unventilated cooling foods were almost twice as likely to cool more slowly than specified in the Food Code guideline. Our data suggest that several best cooling practices can contribute to a proper cooling process. Inspectors unable to assess the full cooling process should consider assessing specific cooling practices as an alternative. Future research could validate our estimation method and study the effect of specific practices on the full

  19. Passive cooling safety system for liquid metal cooled nuclear reactors

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.; Hui, Marvin M.; Berglund, Robert C.

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

  20. THE COOLING OF CORONAL PLASMAS. IV. CATASTROPHIC COOLING OF LOOPS

    SciTech Connect

    Cargill, P. J.; Bradshaw, S. J.

    2013-07-20

    We examine the radiative cooling of coronal loops and demonstrate that the recently identified catastrophic cooling is due to the inability of a loop to sustain radiative/enthalpy cooling below a critical temperature, which can be >1 MK in flares, 0.5-1 MK in active regions, and 0.1 MK in long tenuous loops. Catastrophic cooling is characterized by a rapid fall in coronal temperature, while the coronal density changes by a small amount. Analytic expressions for the critical temperature are derived and show good agreement with numerical results. This effect considerably limits the lifetime of coronal plasmas below the critical temperature.