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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 Astrophysics Data System (ADS)

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

    1993-03-01

    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. 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

  4. 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.

  5. The thermal evolution of IVA iron meteorites: Evidence from metallographic cooling rates.

    NASA Astrophysics Data System (ADS)

    Rasmussen, Kaare L.; Ulff-Møller, Finn; Haack, Henning

    1995-07-01

    Metallographic cooling rates of group IVA iron meteorites have been recalculated based on the most recent Ni diffusion coefficients and phase diagram. The cooling rates are revised upwards by a factor of ca. 15 relative to previous estimates. A large range in cooling rate is found in the low-Ni part of group IVA (Ni < 8.4 wt%), while the high-Ni part shows approximately constant cooling rates. Undercooling is observed only in the high-Ni IVA members. Some of the taenite lamellae in the high-Ni IVA irons, which were apparently affected by moderate undercooling, can, alternatively, be interpreted to have experienced a nonlinear cooling history. The variation in cooling rate of the entire group IVA spans two orders of magnitude (19-3400 K/My). This span is still so large that it constitutes severe problems for both a core origin model and a raisin-bread model but seemingly it does not contradict a model where the parent body is broken up and reassembled after core crystallization but prior to Widmanstätten pattern formation.

  6. Review of the metallographic cooling rates of meteorites and a new model for the planetesimals in which they formed

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1979-01-01

    The cooling rates of meteorites through approximately 900 -650 K, as read from their metal alloy compositions, are reviewed. Metallographic cooling rates are compared with the cooling rates that appear to be required by the K/Ar and Ar-40/Ar-39 ages of five meteorite classes, and discrepancies are found in all cases. Either (1) the metallographic cooling rates (and also Pu-244 fission cooling rates) are systematically in error, being too slow by a factor of approximately 6; or (2) the traditional thermal model for parent meteorite planets (having constant dimension and uniform physical properties) is oversimplified and the Ar closure temperatures for chondrites derived by Turner et al. (1978) are too low. An alternative parent planet model is proposed and numerically modeled, in which accretion of thermally insulating particulate matter, heat generation by Al-26 decay, melting or sintering of the particulate matter into conductive rock, and establishment of the properties of the meteorites occurred concurrently. Meteorite chronologies are somewhat easier to understand in this context, since the initially small, hot (thus sintered and conductive) bodies would have cooled rapidly to isotopic closure, but later cooling might have been much slower as a result of the continued accretion of insulating particulate matter.

  7. The Effects of Shock Metamorphism on Metal Textures and Metallographic Cooling Rates in L-Group Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

    Postshock reheating and rapid cooling have severely disturbed geothermometers and coolingrate indicators in L chondrites. This has generated an ongoing debate on the interpretation of the early thermal history of an 'onion-shell' [1] or a 'rubble-pile' [2] L-chondrite parent body. In order to access the degree that reheating has perturbed metallographic cooling rates (disrupting this early thermal history), we have undertaken a study of textures derived from shock metamorphism and subsequent fast cooling of sulfides and Fe-Ni metals. Classification of shock stage by petrographic analysis [3] was performed on 70 L- chondrite thin sections, 55 Antarctic and 15 non-Antarctic, in order to place each into their appropriate shock stage. Fe-Ni metals from representative samples of each shock stage were studied optically and analyzed chemically with a Cameca SX-50 electron microprobe to obtain textural and chemical data. Meteorites of shock stage S3. Meteorites of S4 shock stage contain features similar to lower-shocked S3s, except that they exhibit more abundant melt pockets with melt droplets larger by an order of magnitude (~10 micrometers in diameter). Samples of shock grade S5 have numerous melt

  8. 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

  9. Controlled Rate Cooling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled-rate cooling is one of several techniques available for the long-term storage of plants in liquid nitrogen. In this technique samples are slowly cooled to an intermediate temperature and then plunged in liquid nitrogen. Controlled rate cooling is based on osmotic regulation of cell conte...

  10. 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.

  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. Rate of runaway evaporative cooling

    SciTech Connect

    Groep, J. van de; Straten, P. van der; Vogels, J. M.

    2011-09-15

    Evaporative cooling is a process that is essential in creating Bose-Einstein condensates in dilute atomic gasses. This process has often been simulated based on a model using a truncated Boltzmann distribution. This model assumes that the energy distribution up to the threshold energy can still be described by a Boltzmann distribution: it assumes detailed balance up to the threshold energy. However, the evolution of the distribution function in time is not taken into account. Here we solve the kinetic Boltzmann equation for a gas undergoing evaporative cooling in a harmonic and linear trap in order to determine the evolution of the energy distribution. The magnitude of the discrepancy with the truncated Boltzmannmodel is calculated by including a polynomial expansion of the distribution function. We find that up to 35% fewer particles are found in the high-energy tail of the distribution with respect to the truncated Boltzmann distribution and up to 15% more collisions are needed to reach quantum degeneracy. Supported by a detailed investigation of the particle loss rate at different energies, we conclude that the limited occupation of high-energy states during the evaporation process causes the lowering of the evaporation speed and efficiency.

  13. Metallographic in situ hybridization.

    PubMed

    Powell, Richard D; Pettay, James D; Powell, William C; Roche, Patrick C; Grogan, Thomas M; Hainfeld, James F; Tubbs, Raymond R

    2007-08-01

    Metallographic methods, in which a target is visualized using a probe or antibody that deposits metal selectively at its binding site, offers many advantages for bright-field in situ hybridization (ISH) detection as well as for other labeling and detection methods. Autometallographically enhanced gold labeling procedures have demonstrated higher sensitivity than conventional enzyme chromogens. Enzyme metallography, a novel procedure in which an enzymatic probe is used to deposit metal directly from solution, has been used to develop bright-field ISH methods for HER2 gene determination in breast cancer and other biopsy specimens. It provides the highest level of sensitivity and resolution, both for visualizing endogenous gene copies in nonamplified tissues and for resolving multiple gene copies to allow copy enumeration in amplified tissues without the need for oil immersion or fluorescence optics. An automated enzyme metallography procedure, silver ISH, has been developed for use in slide-staining instruments. Metallographic staining also provides excellent results for immunohistochemistry and may be combined with other staining procedures for the simultaneous detection of more than one gene or combinations of genes and proteins. PMID:17640553

  14. 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.

  15. The effect of the cooling rate of dental alloys on their amalgamation properties.

    PubMed

    Johnson, L B; Carwile, A C

    1978-05-01

    Silver-tin alloys of various compositions (60-80 atomic % Ag) have been prepared from the melt using cooling rates from about 50 degrees C/hr to about 10(6) degrees C/sec. Structural differences due to the different cooling rates were shown by metallographic and x-ray diffraction techniques. From each composition and cooling rate, powders were then prepared and amalgamated. The amalgams were tested for Hg content, dimensional change during setting, and tensile strength. Changes in cooling rates had some effect on the relative amounts of phases present but primarily affected the grain sizes. In general, the faster the cooling rate, the smaller the grain size; the smaller the grain size, the faster and more uniform the amalgamation; the more uniform the amalgamation, the stronger the amalgam. Storage of the alloy powders at room temperatures slowed their amalgamation rates, destroyed their uniformity,and resulted in weaker amalgams. However, no phase changes were observed by x-ray diffraction in the freshly comminuted alloys after aging at room temperature for two months. PMID:670259

  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. Cooling rate based on schreibersite growth for the Emery mesosiderite

    NASA Technical Reports Server (NTRS)

    Kulpecz, A. A., Jr.; Hewins, R. H.

    1978-01-01

    Computer simulation of diffusion-controlled growth of the large Ni-rich grains of schreibersite found in the Emery mesosiderite indicates that exsolution from kamacite occurred during cooling at the rate of 0.1 C/Myr. This finding agrees with the mesosiderite cooling rate determined by Powell (1969) from taenite-kamacite data. The cooling rate is the lowest found for any meteorite group, and implications for the cooling history, with a possibility of reheating, are considered. The procedure for computing a family of cooling rate curves is based on Randich's (1975) method.

  19. The cooling-rate effect on microwave archeointensity estimates

    NASA Astrophysics Data System (ADS)

    Poletti, Wilbor; Hartmann, Gelvam A.; Hill, Mimi J.; Biggin, Andrew J.; Trindade, Ricardo I. F.

    2013-08-01

    microwave (MW) paleointensity data on historical bricks from Northeast Brazil presented a bias toward higher fields when compared to previous cooling-rate corrected double-heating paleointensity estimates; the same relates to the previously reported values for pottery from Southwestern Pacific islands. A simple theoretical approach suggests that the MW bias in both collections is due to a cooling-rate effect on MW estimates. We then experimentally corrected the MW cooling-rate effect on Brazilian fragments, increasing the degree of consistency between the previous and new results (reducing discrepancies from 25% to 8%). Results indicate similar experimental behavior between microwave and thermal procedures despite the different ways in which the energy is transferred into the spin system. Finally, they allow cooling times of less than 90 s to be empirically estimated in most of these MW experiments highlighting the need for systematic cooling-rate corrections to be applied in similar MW paleointensity studies in the future.

  20. Effect of Grain Refinement and Cooling Rate on the Microstructure and Mechanical Properties of Secondary Al-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Timelli, Giulio; Camicia, Giordano; Ferraro, Stefano

    2013-10-01

    The effect of AlTi5B1 grain refinement and different solidification rates on metallurgical and mechanical properties of a secondary AlSi7Cu3Mg alloy is reported. While the Ti content ranges from 0.04 up to 0.225 wt.%, the cooling rate varies between 0.1 and 5.5 °C/s. Metallographic and thermal analysis techniques have been used to quantitatively examine the macro- and microstructural changes occurring with grain refiner addition at various cooling rates. The results indicate that a small AlTi5B1 addition produces the greatest refinement, while no significant reduction of grain size is obtained with a great amount of grain refiner. On increasing the cooling rate, a lower amount of AlTi5B1 master alloy is necessary to produce a uniform grain size throughout the casting. The combined addition of AlTi5B1 and Sr does not produce any reciprocal interaction or effect on primary α-Al and eutectic solidification. The grain refinement improves the plastic behavior of the alloy and increases the reliability of castings, as evidenced by the Weibull statistics.

  1. 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.

  2. Cooling Rate Determination in Additively Manufactured Aluminum Alloy 2219

    NASA Astrophysics Data System (ADS)

    Brice, Craig A.; Dennis, Noah

    2015-05-01

    Metallic additive manufacturing processes generally utilize a conduction mode, welding-type approach to create beads of deposited material that can be arranged into a three-dimensional structure. As with welding, the cooling rates in the molten pool are relatively rapid compared to traditional casting techniques. Determination of the cooling rate in the molten pool is critical for predicting the solidified microstructure and resultant properties. In this experiment, wire-fed electron beam additive manufacturing was used to melt aluminum alloy 2219 under different thermal boundary conditions. The dendrite arm spacing was measured in the remelted material, and this information was used to estimate cooling rates in the molten pool based on established empirical relationships. The results showed that the thermal boundary conditions have a significant effect on the resulting cooling rate in the molten pool. When thermal conduction is limited due to a small thermal sink, the dendrite arm spacing varies between 15 and 35 µm. When thermal conduction is active, the dendrite arm spacing varies between 6 and 12 µm. This range of dendrite arm spacing implies cooling rates ranging from 5 to 350 K/s. Cooling rates can vary greatly as thermal conditions change during deposition. A cooling rate at the higher end of the range could lead to significant deviation from microstructural equilibrium during solidification.

  3. 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

  4. Crystal/liquid partitioning in augite - Effects of cooling rate

    NASA Technical Reports Server (NTRS)

    Gamble, R. P.; Taylor, L. A.

    1980-01-01

    The partitioning of major and minor elements between augite and melt was determined as a function of cooling rate for two high-titanium basalt compositions. The results of this study of lunar rock systems 10017 and 75055 were compared with the results of other kinetic studies of augite-liquid partitioning in other rock systems. It was found that the partitioning of major elements (i.e., Ca, Fe, Mg) is essentially rate independent and is insensitive to bulk rock composition and to the nature and order of appearance of coexisting phases for cooling rates of less than 100 C/hr. The partitioning behavior of minor elements (i.e., Al, Cr, Ti) for the same range of cooling rates is complex, being dependent on cooling rate and bulk rock composition. Consideration of these factors is important when augite chemistry and/or partitioning behavior are used in modeling certain magmatic processes or in estimating the thermal history of basaltic rocks.

  5. 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%.

  6. Ultrasonic metal etching for metallographic analysis

    NASA Technical Reports Server (NTRS)

    Young, S. G.

    1971-01-01

    Ultrasonic etching delineates microstructural features not discernible in specimens prepared for metallographic analysis by standard chemical etching procedures. Cavitation bubbles in ultrasonically excited water produce preferential damage /etching/ of metallurgical phases or grain boundaries, depending on hardness of metal specimens.

  7. 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

  8. Metallographic preparation of titanium diboride coatings

    SciTech Connect

    McAllaster, M.E.

    1980-03-01

    A method is described for preparing metallographic cross sections of thin, hard, chemically vapor deposited titanium diboride coatings on various softer substrates. Standard metallographic preparation techniques were found to result in fracturing and edge rounding of the coatings. It is shown that these problems can be avoided by unidirectional grinding on worn 600 grit silicon carbide abrasive paper. Typical photomicrographs of chemically vapor deposited titanium diboride coatings are shown along with photomicrographs of intermediate phases that form at the titanium diboride - substrate interfaces.

  9. Computation of atmospheric cooling rates by exact and approximate methods

    NASA Technical Reports Server (NTRS)

    Ridgway, William L.; HARSHVARDHAN; Arking, Albert

    1991-01-01

    Infrared fluxes and cooling rates for several standard model atmospheres, with and without water vapor, carbon dioxide, and ozone, have been calculated using a line-by-line method at 0.01/cm resolution. The sensitivity of the results to the vertical integration scheme and to the model for water vapor continuum absorption is shown. Comparison with similar calculations performed at NOAA/GFDL shows agreement to within 0.5 W/sq m in fluxes at various levels and 0.05 K/d in cooling rates. Comparison with a fast, parameterized radiation code used in climate models reveals a worst case difference, when all gases are included, of 3.7 W/sq m in flux; cooling rate differences are 0.1 K/d or less when integrated over a substantial layer with point differences as large as 0.3 K/d.

  10. Impact of Cooling Rate on the Durability of PHA Glasses

    SciTech Connect

    Edwards, T.B.

    2001-06-04

    This study was conducted to determine the effect, if any, on the PCT responses of glasses cooled at different rates. Two bounding cooling profiles were used in this study: rapidly quenched and a canister centerline cooling curve. Glasses were selected based on a number of criteria, but mainly to challenge the regions where amorphous phase separation is expected based upon current model predictions. The current DWPF homogeneity constraint, imposed to preclude regions of phase separation, predicted that most of the glasses selected would be phase separated. It was, therefore, important to ensure that deleterious phase separation does not occur at either cooling profile. In this case, deleterious phase separation is defined as the formation of an amorphous phase in the glass that significantly decreases the glass durability as measured by the PCT response.

  11. Influence of cooling rate on zirconia/veneer interfacial adhesion.

    PubMed

    Göstemeyer, Gerd; Jendras, Michael; Dittmer, Marc P; Bach, Friedrich-Wilhelm; Stiesch, Meike; Kohorst, Philipp

    2010-12-01

    Slow cooling firing schedules have recently been introduced by some manufacturers to reduce chipping complications in zirconia-based core/veneer composites. The aim of this study was to test the hypothesis that these firing schedules may influence the bond strength between the zirconia core and veneering ceramic. Four different veneering ceramics recommended for zirconia (Lava Ceram, Triceram, VM9 and Zirox) were fired onto rectangular shaped Y-TZP specimens (Lava Frame) and cooled using a rapid or a slow cooling rate. The resulting bilayer specimens were notched, loaded in a four-point bending test and load-displacement curves were recorded. The critical load to induce stable crack extension at the core/veneer interface was determined, in order to calculate the strain energy release rate (G, Jm⁻²). Additionally, dilatometric measurements of the veneering ceramics were performed to determine the coefficient of thermal expansion (α, ppm.K⁻¹) between 50 and 450°C (α₁) and in the temperature region above the glass transition temperature (α₂). Discrepancies between α₂ and α₁ (Δα) were calculated. For all core/veneer compositions G values were lower for the slowly cooled specimens than for the rapidly cooled specimens. Significant differences with respect to the firing schedule were found in the Triceram and VM9 groups (P<0.05). The reductions in G values correlated with Δα. The bond strength between the zirconia core and the veneer decreased with the slow cooling rate. These results indicate that slow cooling of zirconia restorations may increase the risk of adhesive delamination failures between the core and veneer. PMID:20601242

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. Olivine cooling speedometers. [cooling rate indicator for lunar and terrestrial rock thermal histories

    NASA Technical Reports Server (NTRS)

    Onorato, P. I. K.; Uhlmann, D. R.; Taylor, L. A.; Coish, R. A.; Gamble, R. P.

    1978-01-01

    Several kinetic models of zoning in olivines are discussed at length. The effects on predicted cooling rates of various assumptions used in the analyses are evaluated. It is concluded that the models of Walker et al. (1977) and Taylor et al. (1977) both provide underestimates of the cooling rate required to preserve a given compositional profile, and that both models as well as the model of Taylor et al. (1978) can be used to provide order-of-magnitude estimates of cooling rates. A new model is described which considers diffusion in both solid and liquid during crystallization as well as diffusion in the solid after crystallization is complete. The model provides a description of the compositional gradients which develop during crystallization as well as after cooling at various rates. Applied to olivine crystals nucleated at 1272 C in a high-iron analogue to Lunar Composition 15555, the model predicts only slight compositional gradients - in accord with electron beam microprobe measurements on crystals grown isothermally at this temperature.

  17. Effect of local cooling on sweating rate and cold sensation

    NASA Technical Reports Server (NTRS)

    Crawshaw, L. I.; Nadel, E. R.; Stolwijk, J. A. J.; Stamford, B. A.

    1975-01-01

    Subjects resting in a 39 C environment were stimulated in different skin regions with a water-cooled thermode. Results indicate that cooling different body regions produces generally equivalent decreases in sweating rate and increases in cold sensation, with the forehead showing a much greater sensitivity per unit area and temperature decrease than other areas. The high thermal sensitivity of the face may have evolved when it was the thinnest-furred area of the body; today's clothing habits have reestablished the importance of the face in the regulation of body temperature.

  18. Radiative heating and cooling rates in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Gille, John C.; Lyjak, Lawrence V.

    1986-01-01

    One of the limitations to the accurate calculation of radiative heating and cooling rates in the stratosphere and mesosphere has been the lack of accurate data on the atmospheric temperature and composition. Data from the LIMS experiment on Nimbus-7 has been extended to the South Pole with the aid of other observations. The data have been used as input to codes developed by Ramanathan and Dickinson to calculate the individual components and the net radiative heating rates from 100-0.1 mb. Solar heating due to ozone, nitrogen dioxide, carbon dioxide, water vapor and oxygen is shown to be nearly balanced by cooling in the thermal infrared spectral region due to carbon dioxide, ozone and water vapor. In the lower stratosphere, infrared transfer by ozone leads to heating that is sensitive to the distribution of tropospheric ozone, clouds and water vapor. The heating and cooling rates are adjusted slightly in order to satisfy the global mass balance. The results are in qualitative agreement with earlier calculations, but show additional detail. There is as strong temporal and vertical variation of cooling in the tropics. Radiative relaxation times are as short as 7 days or less at the stratopause.

  19. 'Nose method' of calculating critical cooling rates for glass formation

    NASA Technical Reports Server (NTRS)

    Weinberg, Michael C.; Uhlmann, Donald R.; Zanotto, Edgar D.

    1989-01-01

    The use of the so-called 'nose method' for computing critical cooling rates for glass formation is examined and compared with other methods, presenting data for the glass-forming systems SiO2, GeO2, and P2O5. It is shown that, for homogeneous crystallization, the nose-method will give an overestimate of Rc, a conclusion which was drawn after assessing the enfluence of a range of values for the parameters which control crystal growth and nucleation. The paper also proposes an alternative simple procedure (termed the 'cutoff method') for computing critical cooling rates from T-T-T diagrams, which was shown in the SiO2 and GeO2 systems to be superior to the nose method.

  20. Cooling Rate Controls Dihedral Angles in Dolerite Sills

    NASA Astrophysics Data System (ADS)

    Holness, M. B.; Richardson, C.

    2011-12-01

    The median of the population of augite-plagioclase-plagioclase dihedral angles in mafic rocks (Θcpp) varies systematically within layered intrusions. It is not clear from previous work how much of this variation is caused by composition and how much is the consequence of different thermal histories. However, the effect of temperature can be isolated by studying a family of non-fractionated planar-sided mafic bodies of various size (and hence cooling rate). Formation of augite-plag-plag dihedral angles involves the growth of augite into the melt-filled space created by the juxtaposition of two plagioclase grains. Examination of the Kiluaea Iki lava lake demonstrates that growth of interstitial augite grains preferentially occurs where the two plagioclase grains meet at a high angle, while narrower melt pockets tend to cool through the glass transition before the melt crystallizes. Θcpp in the lava lake crust and in other rapidly cooled dolerites is ~78°, higher than the 60° expected if augite perfectly pseudomorphed the melt geometry. In more slowly cooled bodies, augite-plag-plag junctions are not formed by the intersection of two planar augite-plag boundaries, but are curved towards higher angles: Θcpp > 78° and, in the most slowly cooled dolerites, may approach the equilibrium value of 109°. Comparison with layered intrusions demonstrates that the change in geometry with decreased cooling rate is not due to sub-solidus modification but is a consequence of simultaneous growth of the two minerals during the last stages of solidification at the three-grain junction. While this is not yet fully quantified it is likely that the controls on the geometry of three-grain junctions, and therefore the dihedral angle, are the effects of confinement on crystal growth rate and mass transport, together with the variable effects of undercooling on crystal growth mechanisms. We measured Θcpp from 10-15 samples across each of a family of non-fractionated basaltic sills

  1. Hypercapnia increases core temperature cooling rate during snow burial.

    PubMed

    Grissom, Colin K; Radwin, Martin I; Scholand, Mary Beth; Harmston, Chris H; Muetterties, Mark C; Bywater, Tim J

    2004-04-01

    Previous retrospective studies report a core body temperature cooling rate of 3 degrees C/h during avalanche burial. Hypercapnia occurs during avalanche burial secondary to rebreathing expired air, and the effect of hypercapnia on hypothermia during avalanche burial is unknown. The objective of this study was to determine the core temperature cooling rate during snow burial under normocapnic and hypercapnic conditions. We measured rectal core body temperature (T(re)) in 12 subjects buried in compacted snow dressed in a lightweight clothing insulation system during two different study burials. In one burial, subjects breathed with a device (AvaLung 2, Black Diamond Equipment) that resulted in hypercapnia over 30-60 min. In a control burial, subjects were buried under identical conditions with a modified breathing device that maintained normocapnia. Mean snow temperature was -2.5 +/- 2.0 degrees C. Burial time was 49 +/- 14 min in the hypercapnic study and 60 min in the normocapnic study (P = 0.02). Rate of decrease in T(re) was greater with hypercapnia (1.2 degrees C/h by multiple regression analysis, 95% confidence limits of 1.1-1.3 degrees C/h) than with normocapnia (0.7 degrees C/h, 95% confidence limit of 0.6-0.8 degrees C/h). In the hypercapnic study, the fraction of inspired carbon dioxide increased from 1.4 +/- 1.0 to 7.0 +/- 1.4%, minute ventilation increased from 15 +/- 7 to 40 +/- 12 l/min, and oxygen saturation decreased from 97 +/- 1 to 90 +/- 6% (P < 0.01). During the normocapnic study, these parameters remained unchanged. In this study, T(re) cooling rate during snow burial was less than previously reported and was increased by hypercapnia. This may have important implications for prehospital treatment of avalanche burial victims. PMID:14660514

  2. 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.

  3. 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

  4. 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

  5. Secular Cooling Rates of the Mantle : Various Influences

    NASA Astrophysics Data System (ADS)

    Rainey, E.; van den Berg, A. P.; Yuen, D. A.

    2002-12-01

    The history of secular cooling of the mantle is an old important issue, which has been attacked for many years using temperature-dependent viscosity as the primary agent (Tozer, 1972. Phys. Earth Planet. Int., 6, 182-197). In this work we have ventured to look at the impact of variable thermal conductivity on the secular cooling rates predicted by models using just temperature-dependent viscosity. We have found the following salient results. (1) A delayed secular cooling is found as in the constant viscosity models (van den Berg and Yuen, 2002, Earth Planet. Sci. Lett., 199, 403-413, van den Berg et al., 2002, Phys. Earth Planet. Inter., 129, 359-375). We have applied an exponential temperature and pressure dependent viscosity model, using thermal viscosity contrast up to 3000 and fixed presssure viscosity contrast of 100 for this verification. (2) A purely depth-dependent thermal conductivity k(P) cannot catch the destructive effect of temperature dependent conductivity on the negative thermal buoynacy of cold downwellings, driving the convective circulation. These k(P) models also lack feedback physics between time-dependent internal heating and variable thermal conductivity k(T,P), thus stressing the need to use k(T,P) whenever there is a strong source of heat present. (3) Large-differences occur between predictions from 2-D numerical models based on Partial Differential Equations (PDE) and averaged parameterized convection models, formulated using an Ordinary Differential Equation (ODE), within the framework of integrating the nonlinear ODE for the volume average temperature. The ODE results for this comparison are computed using the time series of volume average quantities (viscosity, conductivity) obtained from the 2-D PDE results. The comparison shows that the 1-2 Gyr delay in secular cooling, characteristic for full convection PDE models, is not reproduced in the ODE results from parameterized convection models. The temperature dependence of the ice thermal

  6. Relict Forsterite in Chondrules: Implications for Cooling Rates

    NASA Technical Reports Server (NTRS)

    Greeney, S.; Ruzicka, A.

    2004-01-01

    Forsterite (Fo(sub 99-100)) is often present in chondrules as relict grains that did not crystallize in situ and as isolated grains outside of chondrules; both are surrounded by ferrous overgrowths which clearly formed at a later time, probably during chondrule formation. We performed microprobe analyses across forsterite-overgrowth interfaces in 12 chondrules and 4 isolated grains in the Sahara-97210 LL3.2 (Sahara), Wells LL3.3, and Chainpur LL3.4 chondrites and modelled diffusional exchange between forsterite and overgrowths, with the goal of constraining the thermal histories during chondrule formation. The cooling rates experienced by chondrules provide an important constraint on the origin and setting of these objects.

  7. 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

  8. 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.

  9. Mechanical properties of Rene-41 affected by rate of cooling after solution annealing

    NASA Technical Reports Server (NTRS)

    Prager, M.

    1970-01-01

    Investigation of Rene-41 cooling rate from 1975 to 1400 degrees F reveals that slow cooling improves high-temperature ductility and provides more uniform properties throughout a manifold. Ambient elongation and impact resistance are not significantly changed.

  10. Effects of Cooling Rate on Transformations in a Fe-9 Pct Ni Steel

    NASA Astrophysics Data System (ADS)

    Fonda, Richard W.; Spanos, George

    2014-12-01

    The transformations of a high-strength 9Ni-Cr-Mo-V steel were characterized as a function of cooling rate by dilatometry, microhardness measurements, and microstructural characterization. The results demonstrate that this steel is extremely insensitive to changes in cooling rate, generating a duplex microstructure of coarse autotempered martensite within a matrix of fine lath martensite at nearly all cooling rates. The coarse autotempered martensite is observed even at very slow cooling rates, although the lath martensite becomes replaced by lath (or bainitic) ferrite.

  11. Cooling Rates of the USR as Calculated with BETACOOL

    SciTech Connect

    Welsch, C. P.; Smirnov, A.

    2006-03-20

    The ultra-low energy storage ring (USR) will be a multi-purpose facility providing electron-cooled antiprotons in the energy range between 20 keV and 300 keV for both in-ring experiments and effective injection into traps. The low beam energies and high beam quality to be provided by this accelerator will enable new studies of antimatter/matter interactions using in-ring experiments with an internal gas jet target as well as particle traps, which can be efficiently filled using the decelerated and cooled antiproton beam. High luminosity, low emittance and low momentum spread are some of the main characteristics of the electron-cooled antiproton beam that shall be achieved and that the various experiments may take advantage of. The layout of an electron cooler at such low energies is a great challenge and questions like the competition between multiple scattering and electron cooling, the needed cooling power with an installed internal target or the influence of the electron temperature on the cooling time have to be addressed for the first time. In this contribution, the layout of the USR is summarized and results from simulations with the BETACOOL code are presented.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. On the effect of heating and cooling rates on the melting and crystallization of metal nanoclusters

    NASA Astrophysics Data System (ADS)

    Samsonov, V. M.; Talyzin, I. V.; Samsonov, M. V.

    2016-06-01

    The effect of heating and cooling rates on melting ( T m ) and crystallization ( T c ) temperatures of metal nanoclusters is investigated in terms of the isothermal molecular dynamics. We report on the results obtained for nickel nanoclusters, although analogous results were also obtained for gold and aluminum nanoclusters. It is found that T m increases, while T c decreases with increasing heating and cooling rates, both T m and T c tending to the same value for heating and cooling rates tending to zero. The results indicate that the hysteresis of melting and crystallization of nanoparticles must be completely due to nonequilibrium conditions of heating and cooling. The transition of Ni nanoclusters to the amorphous state begins at very high cooling rates exceeding 10 TK/s.

  20. 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

  1. Effect of cooling rate on achieving thermodynamic equilibrium in uranium-plutonium mixed oxides

    NASA Astrophysics Data System (ADS)

    Vauchy, Romain; Belin, Renaud C.; Robisson, Anne-Charlotte; Hodaj, Fiqiri

    2016-02-01

    In situ X-ray diffraction was used to study the structural changes occurring in uranium-plutonium mixed oxides U1-yPuyO2-x with y = 0.15; 0.28 and 0.45 during cooling from 1773 K to room-temperature under He + 5% H2 atmosphere. We compare the fastest and slowest cooling rates allowed by our apparatus i.e. 2 K s-1 and 0.005 K s-1, respectively. The promptly cooled samples evidenced a phase separation whereas samples cooled slowly did not due to their complete oxidation in contact with the atmosphere during cooling. Besides the composition of the annealing gas mixture, the cooling rate plays a major role on the control of the Oxygen/Metal ratio (O/M) and then on the crystallographic properties of the U1-yPuyO2-x uranium-plutonium mixed oxides.

  2. 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.

  3. Contributions of cooling and warming rate and developmental stage to the survival of Drosophila embryos cooled to -205 degrees C.

    PubMed

    Mazur, P; Cole, K W; Schreuders, P D; Mahowald, A P

    1993-02-01

    Because of their high susceptibility to chilling injury, permeabilized Drosophila embryos can not be cryobiologically preserved by slow freezing at rates low enough to prevent the formation of intraembryonic ice. Calculations indicated that to outrun the chilling injury they must be cooled and warmed rapidly at an estimated 20,000 degrees C/min or faster. Ordinarily, such cooling rates would inevitably produce lethal intracellular ice. To prevent this, embryos must contain and be surrounded by sufficiently high concentrations of glass-promoting solutes to induce vitrification on cooling and prevent devitrification on warming. Like Steponkus et al. (Nature 345, 170, 1990) we have used ethylene glycol as the solute and have exposed permeabilized 12-h embryos to it in two steps. (Permeabilization was effected by exposing dechorionated embryos to a mixture of 0.3% 1-butanol in n-heptane for 90 or 110 s.) The two steps were (i) a 30-min exposure to 2 M ethylene glycol at 23 degrees C and (ii) a 5-min exposure to 8.5 M ethylene glycol [+/- 10% polyvinylpyrrolidone (PVP)] at 5 degrees C. The volumetric response to the first step indicates that full permeation of the 2 M glycol has been approached by 30 min. The point of the second step is to raise the intraembryonic concentration of ethylene glycol to near 8.5 M ethylene glycol by osmotic dehydration. Survival based on hatching is some 45% at this point. When 12-h embryos in 8.5 M glycol containing 10% PVP are then cooled to -205 degrees C at approximately 100,000 degrees C/min and warmed at about that rate, an average of about 12% survive (hatch), although in about half the runs 15-29% survive. Survivals in the absence of PVP are usually poorer but have been as high as 40%. Currently, 5% of the surviving larvae develop to adult flies (Steponkus et al. reported 18% hatching and 3% development to adult). Embryos that develop but do not hatch show readily detectable abnormalities in mouth parts and dorsal closure. Very high

  4. Metallographic approach to the investigation of metallic archaeological objects.

    PubMed

    Pinasco, Maria Rosa; Ienco, Maria Giuseppina; Piccardo, Paolo; Pellati, Gabriella; Stagno, Enrica

    2007-07-01

    Metallic objects are considered among the most significant findings in Cultural Heritage and represent the 'culture of Materials' and the habits of an historical period and of a population. They also preserve traces of time: from the transformation of the ores in metal (by smelting) to the degradation from metal to oxidised compounds (by corrosion processes). Metallography, historically devoted to connect the microstructural features to production processes and to chemical-physical-mechanical properties is a powerful and relatively easy approach to characterise metallic findings. All analytical tools and methods in the hands of a metallographer are improved through experience and practice and provide a large number of information (elemental composition, primary and secondary microstructures, surface treatments, corrosion rate, original ores traces) by the preparation of a fairly small microdestructive sample. A wise and careful use of the metallography allows the balance "object sacrifice/knowledge improvement" to lean on the right side contributing to the hard work of rebuilding humankind history. Beside a description of a research protocol some practical examples concerning archaeological findings are presented in this paper. PMID:17867539

  5. Simplified model evaluation of cooling rates for glass-containing lunar compositions

    NASA Technical Reports Server (NTRS)

    Uhlmann, D. R.; Yinnon, H.; Fang, C.-Y.

    1982-01-01

    The simplified model of glass formation and the development of partial crystallinity in cooled bodies has been applied to lunar compositions 10060, 15028, 15086, 15101, 15286, 15301, 15498, 15499, 60255, 65016, 77017, Apollo 15 green glass and LUNA 24 highland basalt. The critical cooling rates for glass formation predicted by the simplified model are found to be in good agreement (to within an order of magnitude) with those predicted by the exact treatment of crystallization statistics. These predicted critical cooling rates are in even better agreement (a factor of 2) with measured values of the rates required to form glasses of the materials.

  6. Effect of High Cooling Rates on the Mineralogy and Hydraulic Properties of Stainless Steel Slags

    NASA Astrophysics Data System (ADS)

    Kriskova, Lubica; Pontikes, Yiannis; Pandelaers, Lieven; Cizer, Özlem; Jones, Peter Tom; Van Balen, Koen; Blanpain, Bart

    2013-10-01

    This article investigates the effect of chemical composition and cooling rate during solidification on the mineralogy and hydraulic properties of synthetic stainless steel slags. Three synthetic slags, covering the range of typical chemical composition in industrial practice, were subjected to high cooling rates, by melt spinning granulation or quenching in water, and to low cooling rates, by cooling inside the furnace. Both methods of rapid cooling led to volumetrically stable slags unlike the slow cooling which resulted in a powder-like material. Stabilized slags consisted predominantly of lamellar β-dicalcium silicate ( β-C2S) and Mg, Ca-silicates (merwinite and bredigite); the latter form the matrix at low basicity and are segregated along the C2S grain boundaries at high basicities. Slowly cooled slags consist of the γ-C2S polymorph instead of the β-C2S and of less Mg, Ca-silicates. Isothermal conduction calorimetry and thermogravimetric analysis indicate the occurrence of hydration reactions in the stabilized slags after mixing with water, while calcium silicate hydrates (C-S-H) of typical acicular morphology are identified by SEM. The present results demonstrate that the application of high cooling rates can result in a stable, environmental-friendly, hydraulic binder from stainless steel slags, rich in β-C2S, without the necessity of introducing any additions to arrest the β polymorph.

  7. Crystallization history of lunar picritic basalt sample 12002 - Phase-equilibria and cooling-rate studies

    NASA Technical Reports Server (NTRS)

    Walker, D.; Kirkpatrick, R. J.; Longhi, J.; Hays, J. F.

    1976-01-01

    Experimental crystallization of a lunar picrite composition (sample 12002) at controlled linear cooling rates produces systematic changes in the temperature at which crystalline phases appear, in the texture, and in crystal morphology as a function of cooling rate. Phases crystallize in the order olivine, chromium spinel, pyroxene, plagioclase, and ilmenite during equilibrium crystallization, but ilmenite and plagioclase reverse their order of appearance and silica crystallizes in the groundmass during controlled cooling experiments. The partition of iron and magnesium between olivine and liquid is independent of cooling rate, temperature, and pressure. Comparison of the olivine nucleation densities in the lunar sample and in the experiments indicates that the sample began cooling at about 1 deg C/hr. Pyroxene size, chemistry, and growth instability spacings, as well as groundmass coarseness, all suggest that the cooling rate subsequently decreased by as much as a factor of 10 or more. The porphyritic texture of this sample, then, is produced at a decreasing, rather than a discontinuously increasing, cooling rate.

  8. Impact of cooling rate on the morphology of coalescence silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Hudson, George A.; Li, Jianbo; Wang, Lichang

    2010-09-01

    The effects of the kinetic energy of the colliding Ag clusters, the cooling rate, and the reaction chamber temperature on the structures of product Ag particles were studied using molecular dynamics simulations with a cluster Sutton-Chen potential. The results show that cooling rate is the most significant factor in the structure of the final product. A cooling rate of 1.5625 × 10 11 K/s with a chamber temperature of 300 K generates a crystalline structure. In contrast, a rapid cooling rate, 1.5625 × 10 13 K/s, is more likely to produce an amorphous structure due to the lack of enough kinetic energy to overcome potential barriers.

  9. 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.

  10. Effect of Cooling Rate on Microstructure and Charge Transport in Semiconducting Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Kang, Evan; Kim, Eunseong; CenterSupersolid; Quantum Matter Research Team

    2011-03-01

    Thermal annealing of polymer thin films often enhances charge carrier mobility which can be attributed to self-healing of the film morphology. We have investigated the effect of cooling rate following the annealing treatment on the thin film microstructure and the charge transport properties using a high performance semiconducting polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). The cooling rate plays a key role in determining the microstructure and performance of polymer thin films. Differential scanning calorimeter measurement shows that fast cooling suppresses the crystallization process. The microstructure of thin films is investigated by using 2D X-ray diffraction and atomic force microscopy. Slow cooling results in well-connected large domains with enhanced three dimensional ordering whereas fast cooling leads to misalignment of small domains with relatively rough surface. Transport characteristics at various temperatures show increase in the charge carrier mobility and decrease in the activation energy when the cooling rate is slowed. This change in the mobility and activation energy becomes saturated with cooling rate below 15 °C/min. E. S. H. K. and E. K. gratefully acknowledge financial support from the National Research Foundation of Korea through the Creative Research Initiatives (CSQR).

  11. Effect of Cooling Rate on Microstructure and Mechanical Properties of Thin-Walled Ductile Iron Castings

    NASA Astrophysics Data System (ADS)

    Górny, Marcin; Tyrała, Edward

    2013-01-01

    This article addresses the effect of cooling rate on microstructure and mechanical properties as determined by changing molding media and section size. The research was conducted for thin-walled iron castings with 2-5-mm wall thickness and for the reference casting with 13-mm wall thickness, using different molding materials (silica sand and insulating sand "LDASC") to achieve various cooling rates. Thermal analysis was performed to determine the real cooling rate at the beginning of the graphite eutectic solidification. In general, it was found that the predictions based on theoretical analysis of the solidification process of ductile iron are in good agreement with the experimental outcomes. Finally, the present study provides insights into the effect of cooling rate on the graphite nodule count, the ferrite fraction and mechanical properties of thin-walled ductile iron castings. The study shows that the cooling rate of thin-walled castings varies in a wide range (80-15 °C/s) when changing the wall thickness from 2 to 5 mm, accompanied by significantly changing the mechanical properties of ductile iron. The cooling rate can be effectively reduced by applying an insulating sand to obtain the desired properties of thin-walled castings practically in the whole range of ductile iron grades in accordance with the ASTM Standard.

  12. Combining Hf-W Ages, Cooling Rates, and Thermal Models to Estimate the Accretion Time of Iron Meteorite Parent Bodies

    NASA Astrophysics Data System (ADS)

    Qin, L.; Dauphas, N.; Wadhwa, M.; Masarik, J.; Janney, P. E.

    2007-12-01

    The 182Hf-182W short-lived chronometer has been widely used to date metal-silicate differentiation processes in the early Solar System. However the presence of cosmogenic effects from exposure to GCR can potentially hamper the use of this system for chronology purposes (e.g. [1,2]). These effects must be corrected for in order to calculate metal-silicate differentiation ages. In this study, high-precision W isotope measurements are presented for 32 iron meteorites from 8 magmatic and 2 non-magmatic groups. Exposure ages and pre- atmospheric size estimates are available for most of these samples [3]. Our precision is better than or comparable to the currently most precise literature data and our results agree with previous work [4]. All magmatic irons have ɛ182W equal within error to or more negative than the Solar System initial derived from a CAI isochron [5]. Iron meteorites from the same magmatic groups show variations in ɛ182W. These are most easily explained by exposure to cosmic rays in space. A correction method was developed to estimate pre-exposure ɛ182W for individual iron meteorite groups. Metal-silicate differentiation in most iron meteorite parent bodies must have occurred within 2 Myr of formation of refractory inclusions. For the first time, we combine 182Hf-182W ages with parent body sizes inferred from metallographic cooling rates in a thermal model to constrain the accretion time of iron meteorite parent bodies. The estimated accretion ages are within 1.5 Myr for most magmatic groups, and could be as early as 0.2 Myr after CAI formation. This is consistent with the study of Bottke et al. [6] who argued that iron meteorite parent bodies could represent an early generation of planetesimals formed in the inner region of the Solar System. [1] Masarik J. (1997) EPSL 152, 181-185. [2] Markowski A. et al. (2006) EPSL 250,104-115. [3] Voshage H. (1984) EPSL 71, 181-194. [4] Markowski A. et al. (2006) EPSL 242, 1-15. [5] Kleine T. et al. (2005) GCA 69

  13. Aging of an aluminum alloy resulting from variations in the cooling rate

    SciTech Connect

    Cavazos, J.L.; Colas, R.

    1999-10-01

    The effect that the rate of cooling after solubilization exerts on the aging behavior of an aluminum heat treatable alloy was studied. Bars of the alloy were heated in a box furnace for solubilization, and after this was achieved they were cooled to room temperature by placing one end in a shallow tank of water. Thermal evolution along the bar was registered with the aid of thermocouples connected to a PC-based data logging system. Small samples were cut from the bars and aged for different times and temperatures. Results from microhardness tests indicate that peak hardness, at a given aging temperature, augments with the increase of the cooling rate until a certain value is achieved, above which the hardness remains constant. This feature was found to be due to precipitation taking place at the lower cooling rates.

  14. Can reptile embryos influence their own rates of heating and cooling?

    PubMed

    Du, Wei-Guo; Tu, Ming-Chung; Radder, Rajkumar S; Shine, Richard

    2013-01-01

    Previous investigations have assumed that embryos lack the capacity of physiological thermoregulation until they are large enough for their own metabolic heat production to influence nest temperatures. Contrary to intuition, reptile embryos may be capable of physiological thermoregulation. In our experiments, egg-sized objects (dead or infertile eggs, water-filled balloons, glass jars) cooled down more rapidly than they heated up, whereas live snake eggs heated more rapidly than they cooled. In a nest with diel thermal fluctuations, that hysteresis could increase the embryo's effective incubation temperature. The mechanisms for controlling rates of thermal exchange are unclear, but may involve facultative adjustment of blood flow. Heart rates of snake embryos were higher during cooling than during heating, the opposite pattern to that seen in adult reptiles. Our data challenge the view of reptile eggs as thermally passive, and suggest that embryos of reptile species with large eggs can influence their own rates of heating and cooling. PMID:23826200

  15. 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).

  16. 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

  17. Optimal rates for cooling chicken semen from +5 to -196 C.

    PubMed

    Sexton, T J

    1980-12-01

    Optimal rates for cooling chicken semen from +5 to -196 C were determined. Semen was diluted 1:5 with Beltsville Poultry Semen Extender and held at 5 C for 2 hr before adding dimethylsulfoxide (DMSO), 4% v/v. The semen-DMSO mixture was allowed to equilibrate for 2 hr at 5 C before it was placed in a plastic freeze straw of .5 cc capacity. A two step controlled-rate procedure was used to test the various cooling rates (1 to 50 C/min) through certain temperature ranges (+5 to -20 C and -20 to -180 C) and to determine the optimal semen temperature for making the transition of cooling in alcohol (Step 1) to cooling in liquid nitrogen (LN2) vapor (Step 2). Fertilizing capacity of spermatozoa was maximal when semen samples were cooled from +5 C to -20 C at a rate of 1 C/min (Step 1), then transferred to LN2 vapor (Step 2) and cooled to -80 C at 30 C/min before the samples were plunged in liquid nitrogen. After storage in LN2 for 24 hr and subsequent thawing at +2 C, the fertilizing capacity of the sperm was 47%. PMID:7267522

  18. Investigation of annular flow at high evaporation rates in view of liquid film cooling

    NASA Astrophysics Data System (ADS)

    Nahstoll, Juergen

    1988-01-01

    The process of liquid film cooling of combustion chamber walls which are subjected to extremely high heat rates was investigated. A theoretical model was developed for a reliable prediction of the film cooling length. The mass transfer at the liquid-gas interface results from evaporated liquid and entrained liquid droplets. The film cooling length analysis, which includes the physical effects in detail, is separated into two regions: heating the liquid and evaporating the liquid. The theoretical results were experimentally verified at high pressures and temperatures using a modified H2/O2-rocket motor. There is a good agreement between the theoretical and the experimental results over the experimental range.

  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. Trace element partitioning between taenite and kamacite - Relationship to the cooling rates of iron meteorites

    NASA Technical Reports Server (NTRS)

    Rasmussen, Kaare L.; Malvin, Daniel J.; Wasson, John T.

    1988-01-01

    Instrumental neutron activation analysis (INAA) was used to determine Ni, Co, Cu, Ga, As, Au, W, Re and Ir in taenite lamellae isolated by acid dissolution from eight iron meteorites from groups IA, IIIAB and IVA. Taenite is enriched in Ni, Cu, Ga, As, Au, W, Re and Ir relative to kamacite, whereas taenite is depleted in Co. Taenite/kamacite partition ratios in slowly cooled IAB meteorites are farther from unity than those in rapidly cooled IVA meteorites. Taenite/kamacite partition ratios for Cu, Ir, Au and Co may be sensitive cooling rate indicators.

  1. Cooling rates dependence of medium range order development in metallic glasses

    NASA Astrophysics Data System (ADS)

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

    Rapid cooling from metallic liquids is a widely used approach to synthesize novel alloys with desirable properties because such rapid cooling drives phase selection away from equilibrium phases resulting in new metastable phases and morphologies. However, molecular dynamics simulation of such rapid solidifications faces a well-known time-scale challenge that the cooling rate is several orders of magnitude faster than experiments. We propose an efficient cooling strategy in which most of the computer time is spent on a prolonged isothermal process slightly below the glass-transition temperature Tg. Such a sub-Tg annealing reduces the effective cooling rates in MD simulations to ~107 K/s. The effects of lowering cooling rates on the evolution of short-range and medium-range orders are investigated. The glassy samples prepared in this way demonstrate significant energetic stability, slow dynamics, and well-developed short-range and medium-range orders. Work supported by DOE-BES under Contract No. DE-AC02-07CH11358.

  2. 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.

  3. Solid water phantom heat conduction: Heating and cooling rates.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2008-01-01

    Solid water is often the phantom material of choice for dosimetry procedures in radiotherapy high-energy X-ray and electron beam radiation calibration and quality assurance. This note investigates variation in heat conduction that can occur for a common commercially available solid water stack phantom when a temperature differential occurs between the phantom and ambient temperature. These variations in temperature can then affect radiation measurements and thus the accuracy of radiation dosimetry. In this manuscript, we aim to investigate the variations in temperature which can occur in radiation measurement incorporated (RMI) solid water phantoms, their thermal properties and the effects on radiation dosimetry which can occur because of temperature differentials. Results have shown that the rate of temperature change at a phantom center is a complex function but appears relatively proportional to the surface area of the phantom in normal clinical usage. It is also dependent on the thermal conductivity of any material in contact with the phantom; and the nature of the phantom construction, i.e., the number and thickness of slices within the phantom. A thermal time constant of approximately 20 min was measured for a 2-cm solid water phantom slice when located on a steel workbench in comparison to 60 min when located on a wooden workbench (linac couch insert). It is found that for larger solid water stack phantoms, a transient (within 1 degrees C) thermal equilibrium exists at the center for up to 2 h, before the temperature begins to change. This is assumed to be due to the insulating properties of multiple slices within the stack, whereby very small air spaces are introduced inhibiting the heat conduction through the phantom material. It is therefore recommended that the solid water/phantom material is kept within the treatment room for closest thermal accuracy conditions or at least placed within the room approximately 10 h before dosimetry measurements. If these

  4. 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

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

    PubMed

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

    2013-10-01

    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 to 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 0.1M sucrose or raffinose (P < 0.05). This study showed that TES extender containing 0.1 M raffinose or sucrose with 70°C/min and

  6. Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films.

    PubMed

    Glor, Ethan C; Fakhraai, Zahra

    2016-01-01

    This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (τα) regimes relevant to the glass transition (τα > 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (τα < 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment. PMID:26863256

  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. 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

  9. Structural origin underlying the effect of cooling rate on solidification point

    NASA Astrophysics Data System (ADS)

    Li, Chen-Hui; Han, Xiu-Jun; Luan, Ying-Wei; Li, Jian-Guo

    2015-11-01

    Solidification behaviors of liquid aluminum at different cooling rates were examined via classical molecular dynamics simulation with an embedded atom method potential. The results demonstrate that solidification point decreases with increasing cooling rate. To explain this phenomenon, solid-like cluster in liquid was analyzed by the structural analysis method of bond order parameters. The results reveal that the size of the largest solid-like cluster in deeply undercooled liquid decreases with the increase of cooling rate, which can provide a structural interpretation to the above phenomenon. Project supported by the National Basic Research Program of China (Grant No. 2011CB012900), the National Natural Science Foundation of China (Grant No. 51171115), the Natural Science Foundation of Shanghai City, China (Grant No. 10ZR1415700), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100073120008), the Program for New Century Excellent Talents in Universities of China. This work is partially supported by Alexander von Humboldt Foundation.

  10. Influence of Weld Cooling Rate on Microstructure and Mechanical Properties of Alloy 718 Weldments

    NASA Astrophysics Data System (ADS)

    Sivaprasad, K.; Ganesh Sundara Raman, S.

    2008-09-01

    Even though alloy 718 is the best for welding among all nickel-base superalloys, the formation of the Laves phase in welds is a major concern. The presence of this phase drastically degrades mechanical properties of the welds. To study the influence of weld cooling rate on microstructure and mechanical properties of alloy 718 weldments, two distinct welding processes were adopted—gas tungsten arc (GTA) and electron beam (EB) welding. The EB welding resulted in finer and relatively discrete Laves phase in lower quantity due to higher cooling rates prevailing in this process. On the other hand, due to lower cooling rates, GTA weld fusion zones exhibited coarse Laves with higher niobium. Depletion of the primary strengthening element niobium in the surrounding regions of Laves promoted crack propagation. Because EB welds had finer and lower amount of Laves, EB weldments exhibited superior mechanical properties compared with GTA weldments.

  11. 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.

  12. 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

  13. An analytical method to evaluate cooling rates during cryopreservation protocols for organs.

    PubMed

    Rubinsky, B; Cravalho, E G

    1984-06-01

    A simple, graphical procedure has been established to estimate the cooling rates at a specified location and temperature in a biological medium frozen by imposing a constant cooling rate at the outer surface. The graphical procedure also facilitates the determination of the outer surface temperature at the instant a given temperature has been attained in a specific location. The results obtained through a numerical study using finite elements can be applied to biological media with various chemical compositions including different concentrations of cryoprotective agents. PMID:6734241

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. An exact calculation of infrared cooling rate due to water vapor

    NASA Astrophysics Data System (ADS)

    Xu, Li; Shi, Guangyu

    1985-11-01

    The longwave (0-2380 cm-1) cooling rate due to water vapor in the troposphere and the stratosphere has been calculated by a new infrared transmission model in this paper. An exact scheme is used for treating the integration over wavenumber and the inhomogeneous path in the atmosphere. It is shown that the atmospheric window region (730-1200 cm-1) (mainly water vapor continuum) plays an important role in the total cooling near the surface, about 72% of the total cooling lying in this region at the height of 1 km; the CG approximation used for an inhomogeneous path is fairly applicable for calculating the cooling rate due to water vapor, with a maximum error of 0.16 K/day throughout the troposhere and the stratosphere; on the other hand, the error due to the diffusivity factor of 1.66 appears to be slightly larger near the surface. In this study, the influences on the calculation of above infrared cooling rate, of the temperature-dependence of the absorption coefficients of water vapor, the upper level cutoff and the integration step for altitude, and the substitution of the quasi-grey approximation for the exact integration over wavenumber, are also examined.

  19. 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.

  20. 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

  1. Ice nucleation in the upper troposphere: Sensitivity to aerosol number density, temperature, and cooling rate

    SciTech Connect

    Jensen, E.J.; Toon, O.B.

    1994-09-01

    We have investigated the processes that control ice crystal nucleation in the upper troposphere using a numerical model. Nucleation of ice resulting from cooling was simulated for a range of aerosol number densities, initial temperatures, and cooling rates. In contrast to observations of stratus clouds, we find that the number of ice crystals that nucleate in cirrus is relatively insensitive to the number of aerosols present. The ice crystal size distribution at the end of the nucleation process is unaffected by the assumed initial aerosol number density. Essentially, nucleation continues until enough ice crystals are present such that their deposition growth rapidly depletes the vapor and shuts off any further nucleation. However, the number of ice crystals nucleated increases rapidly with decreasing initial temperature and increasing cooling rate. This temperature dependence alone could explain the large ice crystal number density observed in very cold tropical cirrus.

  2. Interdependence between Cooling Rate, Microstructure and Porosity in Mg Alloy AE42

    SciTech Connect

    Wang, Liang; Rhee, Hongjoo; Felicelli, Sergio D.; Sabau, Adrian S; Berry, John T.

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation during the gravity-poured castings of magnesium alloy AE42. Two graphite plate molds and a ceramic cylindrical mold were selected to produce a wide range of cooling rates. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at two or three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. The results of this study revealed the existence of oxide film defects, similar to those observed in aluminum alloys. The cooling rates showed significant effect on the formation of porosity.

  3. Evaluation of cryoprotectant and cooling rate for sperm cryopreservation in the euryhaline fish medaka Oryzias latipes.

    PubMed

    Yang, Huiping; Norris, Michelle; Winn, Richard; Tiersch, Terrence R

    2010-10-01

    Medaka Oryzias latipes is a well-recognized biomedical fish model because of advantageous features such as small body size, transparency of embryos, and established techniques for gene knockout and modification. The goal of this study was to evaluate two critical factors, cryoprotectant and cooling rate, for sperm cryopreservation in 0.25-ml French straws. The objectives were to: (1) evaluate the acute toxicity of methanol, 2-methoxyethanol (ME), dimethyl sulfoxide (Me(2)SO), N,N-dimethylacetamide (DMA), N,N-dimethyl formamide (DMF), and glycerol with concentrations of 5%, 10%, and 15% for 60min of incubation at 4°C; (2) evaluate cooling rates from 5 to 25°C/min for freezing and their interaction with cryoprotectants, and (3) test fertility of thawed sperm cryopreserved with selected cryoprotectants and associated cooling rates. Evaluation of cryoprotectant toxicity showed that methanol and ME (5% and 10%) did not change the sperm motility after 30min; Me(2)SO, DMA, and DMF (10% and 15%) and glycerol (5%, 10% and 15%) significantly decreased the motility of sperm within 1min after mixing. Based on these results, methanol and ME were selected as cryoprotectants (10%) to evaluate with different cooling rates (from 5 to 25°C/min) and were compared to Me(2)SO and DMF (10%) (based on their use as cryoprotectants in previous publications). Post-thaw motility was affected by cryoprotectant, cooling rate, and their interaction (P⩽0.000). The highest post-thaw motility (50±10%) was observed at a cooling rate of 10°C/min with methanol as cryoprotectant. Comparable post-thaw motility (37±12%) was obtained at a cooling rate of 15°C/min with ME as cryoprotectant. With DMF, post-thaw motility at all cooling rates was ⩽10% which was significantly lower than that of methanol and ME. With Me(2)SO, post-thaw motilities were less than 1% at all cooling rates, and significantly lower compared to the other three cryoprotectants (P⩽0.000). When sperm from individual males

  4. 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.

  5. Investigation on the Effect of Cooling Rate on Hot Tearing Susceptibility of Al2024 Alloy Using Thermal Analysis

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Effect of different cooling rates and Al-5Ti-1B grain refiner on hot tearing susceptibility of Al2024 alloy were studied using thermal analysis. Influence of cooling rates on microsegregation, and the amount of gas and shrinkage porosities was investigated. The cooling rates used in the present study range from 0.4 to 17.5 K s-1. To evaluate the hot tearing susceptibility, Clyne and Davies' criterion is used. To calculate solid fraction during solidification, solid fraction vs time is plotted based on Newtonian technique via thermal analysis. The results show that the hot tearing susceptibility reduces initially by increasing the cooling rate and then increases at higher cooling rates. Hot tearing susceptibility is decreased by grain refinement. Solidification characteristics of Al2024 e.g., microsegregation, gas, and shrinkage porosities are decreased by increasing cooling rate.

  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. Effect of cooling rate during solidification on the structure of high-speed steel powder particles

    SciTech Connect

    Ershova, L.S.; Smirnov, V.P.

    1985-08-01

    The structure and properties of a P/M high-speed steel form during solidification, hot plastic working, and subsequent heat treatment are the focus here. The character of steel structure variation under the action of high cooling rates during solidification has not yet been sufficiently investigated, therefore it is of interest to study the interrelationship between these factors. An R6M5F3 steel powder was produced by the atomization of molten metal in an apparatus constructed at the Ukranian Scientific-Research Institute of Special Steels, and divided into several fractions. A study was then made of the effect of cooling rate on the phase composition of the steel, degree of alloying of its solid solution and the microstructure and microhardness of the material. As a result of a higher rate of cooling, the amount of metastable M2C carbide inclusions in the structure of P/M R6M5F3 steel increases and the degree of bulk alloying of its grains grows. The increase in the microhardness of powder particles brought about by cooling at a higher rate is due to the formation of finer carbide inclusions during solidification, grain refinement, and an increased degree of alloying of the gamma and alpha solid solutions being formed.

  8. Comparative Cryopreservation of Avian Spermatozoa: Effects of Cooling and Thawing Rates on Sperm Viability and Fertility

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A comparative approach (Sandhill crane (Grus canadensis, n = 13); domestic white turkey (Meleagridis gallopavo n = 40) was used to determine the possible benefits of the addition of different compounds and variation in cooling and thawing rates, and volume of semen. Sperm was frozen in cryovials usi...

  9. Alcohol lowers the vasoconstriction threshold in humans without affecting core cooling rate during mild cold exposure.

    PubMed

    Johnston, C E; Bristow, G K; Elias, D A; Giesbrecht, G G

    1996-01-01

    Elevated blood alcohol levels are often seen in hypothermia and hyperthermia related deaths, leading to the belief that alcohol renders humans poikilothermic. We examined the core temperature (Tco) thresholds for sweating, vasoconstriction and shivering as well as core cooling rates of seven subjects immersed in 28 degrees C water. On two separate days, subjects exercised on an underwater cycle ergometer to elevate Tco above the sweating threshold. They then rested and cooled until they shivered vigorously. Subjects drank orange juice (7 ml.kg-1) prior to immersion during the control trial and 1 ml.kg-1 absolute ethanol, added to orange juice in a 1:6 ratio, during the alcohol trial. Mean blood alcohol concentration (breath analysis) was 0.097 +/- 0.010 g% at the start of cooling and 0.077 +/- 0.008 g% at the end of the cooling period. Alcohol lowered the vasoconstriction threshold by 0.32 +/- 0.2 degrees C and elevated finger tip blood flow, but had no effect on thresholds for sweating and shivering or core cooling rate. Considering these minor effects it is unlikely that moderate alcohol consumption predisposes individuals to hypothermia or hyperthermia via impaired thermoregulation, but rather likely due to behavioral factors. PMID:8897037

  10. 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.

  11. 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 PAGESBeta

    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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. Cooling rate- and hydrogen content-dependent hydride reorientation and mechanical property degradation of Zr-Nb alloy claddings

    NASA Astrophysics Data System (ADS)

    Min, Su-Jeong; Kim, Myeong-Su; Kim, Kyu-Tae

    2013-10-01

    As-received, 250 ppm and 500 ppm hydrogen-charged Zr-Nb alloy cladding tubes were employed to evaluate the effects of cooling rates on the extent of radial hydride formation and mechanical property degradations using the cooling rates of 0.3, 2.0, 4.0 and 15.0 °C/min from 400 °C to room temperature under a tensile hoop stress of 150 MPa, which may simulate a long-term cladding cool-down during an interim dry storage. The hydrogen-charged claddings showed the larger fraction and the longer average length of the radial hydrides with the slower cooling rate. These effects are more dominant for the 250 ppm-H cladding tubes than for the 500 ppm-H cladding tubes. The cooling rate- and the hydrogen content-dependent radial hydride morphology may be explained by the difference in the remaining circumferential hydride fraction at 400 °C and the cooling rate-dependent hydride nucleation and growth rates. The extent of the mechanical property degradations for the hydrogen-charged cladding tubes becomes larger with the decrease of the cooling rate and for the 250 ppm-H specimens. These phenomena are well correlated with the cooling rate- and the hydrogen content-dependent radial hydride fraction and length.

  5. Near conductive cooling rates in the upper-plutonic section of crust formed at the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Faak, Kathrin; Coogan, Laurence A.; Chakraborty, Sumit

    2015-08-01

    A new geospeedometer, based on diffusion modeling of Mg in plagioclase, is used to determine cooling rates of the upper section of the lower oceanic crust formed at fast-spreading mid-ocean ridges. The investigated natural sample suites include gabbroic rocks formed at three different locations along the fast-spreading East Pacific Rise. These samples cover a depth interval of 0-840 m below the sheeted dike/gabbro boundary and therefore allow the variation of cooling rate as a function of depth within the upper plutonic sequence to be determined. We demonstrate that the cooling rates we obtained are robust (reproducible and consistent across different vertical sections at fast spreading ridges) and decrease significantly with increasing sample depth (covering almost 4 orders of magnitude, ranging from ∼1 °C y-1 for the shallowest samples to 0.0003 °C y-1 for the deepest samples). Both the absolute cooling rates, and the rate of decrease of cooling rate with depth, are consistent with conductive thermal models. In contrast, the absolute cooling rates determined from the deeper samples (>300 m below DGB), and the large decrease in cooling rate with depth are inconsistent with thermal models that include substantial cooling by off-axis hydrothermal circulation within the upper plutonic section of the crust.

  6. 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.

  7. Rapid methods of determining cooling rates of iron and stony iron meteorites

    USGS Publications Warehouse

    Short, J.M.; Goldstein, J.I.

    1967-01-01

    Two rapid and simple methods have been developed for determining the approximate cooling rates of iron and stony-iron meteorites in which kamacite formed by diffusion-controlled growth along planar fronts. The first method requires only measurements of the mean kamacite bandwidth and the bulk nickel content. The second method requires the determination of the nickel composition near the taenite-kamacite interface with an electron microprobe.

  8. 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

  9. Coupled Velocity and Cooling Effectiveness Measurements of a Film Cooling Hole With Varied Blowing Rates and Ejection Angles

    NASA Astrophysics Data System (ADS)

    Issakhanian, Emin; Elkins, Chris J.; Eaton, John K.

    2010-11-01

    Film cooling is used to shield turbine blades from combustion gases which are at temperatures above the melting point of the blade's constituent alloy. Maximizing film cooling effectiveness allows higher combustion temperatures and decreases need for bypass air. The present experiment studies flow through a single film cooling hole jetting into a square channel. The momentum thickness Reynolds number of the main flow is 500. The diameter of the cooling flow is 10 times the momentum thickness at the hole exit. The cooling flow Reynolds number varies between 1250 and 5000. Magnetic Resonance Velocimetry (MRV) and Concentration (MRC) are used to measure mean velocity and coolant concentration of the 3-D field both inside the main channel and inside the cooling hole and feed plenum. By marking only the main flow with a passive scalar, the MRC data allow measurement of cooling flow concentration, which by analogy is related to the temperature of the fluid. The velocity data shows the development of a counter-rotating vortex pair downstream of the jet. These vortices transport cooling flow away from the channel floor resulting in a lifted kidney-shaped coolant cross-section and reduced effectiveness. The varying strength of this flow feature and of surface effectiveness due to different ejection angles and blowing ratios is studied.

  10. Theoretical estimation of the radiative cooling rate in the Jovian troposphere

    NASA Astrophysics Data System (ADS)

    Takahashi, Yasuto; Hashimoto, George L.; Ishiwatari, Masaki; Takahashi, Yoshiyuki O.; Sugiyama, Ko-ichiro; Onishi, Masanori; Kuramoto, Kiyoshi

    2015-11-01

    Jupiter exhibits characteristic cloud activities but their physical mechanism remains poorly understood. Recently, Sugiyama et al. (2014) demonstrated that the Jovian cloud convection may have a significant intermittency in the generation of cumulonimbus clouds with the typical interval length controlled by the radiative cooling rate in the upper troposphere. In spite of such importance as a controlling factor of cloud activity, the tropospheric radiative cooling rate profile has never been systematically quantified for the Jovian system. In the Jovian troposphere, condensable species (NH3, H2S, H2O) and their condensates might significantly contribute to radiative transfer.Here we show numerical estimates of radiative cooling rate profile under Jovian troposphere condition by using our non-gray radiative transfer model that contains optical properties of gas species (H2, He, H2O, CH4, NH3, H2S, and PH3) and cloud layers made of H2O, NH4SH, and NH3 ice particles. The temperature profile is determined by the radiative-convective equilibrium state satisfying an observed potential temperature of Jovian troposphere. The mean vertical distributions of gas and cloud are given on the basis of the latest hydrodynamic simulation of Jovian cloud convection (Sugiyama et al., 2014) and cosmochemical consideration.The modeled atmosphere has the tropopause at ~0.38 bar level. The radiative cooling rate reaches the maximum 15 x 10-3 K/Jovian day at ~0.5 bar level, then decreases with depth and approaches zero below 5 bar level. This profile is largely determined by the thermal absorption and emission due to gaseous NH3 and H2 with a slight modification by solar heating due to CH4. The cloud layers are found to have only a weak effect on either radiative cooling or heating because their opacities in the longwave radiation are estimated to be very small, which agrees with the observed 5-micron spectrum with high brightness temperatures. The uncertainty in H2O abundance in deep

  11. Critical cooling rate and thermal stability of Zr--Ti--Cu--Ni--Be alloys

    SciTech Connect

    Waniuk, Theodore A.; Schroers, Jan; Johnson, William L.

    2001-02-26

    The critical cooling rate as well as the thermal stability are measured for a series of alloys in the Zr--Ti--Cu--Ni--Be system. Upon cooling from the molten state with different rates, alloys with compositions ranging along a tie line from (Zr{sub 70}Ti{sub 30}){sub 55}(Ni{sub 39}Cu{sub 61}){sub 25}Be{sub 20} to (Zr{sub 85}Ti{sub 15}){sub 55}(Ni{sub 57}Cu{sub 43}){sub 22.5}Be{sub 27.5} show a continuous increase in the critical cooling rate to suppress crystallization. In contrast, thermal analysis of the same alloys shows that the undercooled liquid region, the temperature difference between the glass transition temperature and the crystallization temperature, is largest for some compositions midway between the two endpoints, revealing that glass forming ability does not correlate with thermal stability. The relationship between the composition-dependent glass forming ability and thermal stability is discussed with reference to a chemical decomposition process.

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

    Energy Science and Technology Software Center (ESTSC)

    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

  13. Foil Cooling for the Rep-Rated Electron Beam Pumped Electra Laser

    NASA Astrophysics Data System (ADS)

    Giuliani, J. L.; Hegeler, F.; Wolford, M. F.; Abdel-Khalik, S.

    2005-10-01

    The Electra program at the Naval Research Laboratory is developing the science and technologies for implementation of krypton-fluoride (KrF) lasers in inertial fusion energy. Large aperture KrF lasers are pumped by electron beams which transit a foil separating the gas target at >=1 atm pressure from the vacuum diode. A fraction of the beam energy is deposited in the foil and thus long term (>=10^8 shots), rep-rated (5 Hz) operation requires active cooling of the foil to prevent thermal yield relaxation and cycling fatigue. This paper will report on experimental data and theoretical analysis of two diverse approaches to foil thermal management: convective and conductive cooling. Convective turbulent cooling has been operational on the Electra main amp through the use of oscillating louvers within a gas recirculator containing the pumped lasing region. At 5 Hz the foil temperature (Tf) can be maintained at ˜400 ^oC for a 1 mil SS foil. Conduction cooling provides the simplest configuration with only the need for water channels in the ribs of the hibachi. For a 1 mil Al foil, Tf is predicted to be ˜140 ^oC at 5 Hz. Comparison of experimental and theoretical results and advanced foil materials will be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    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. Traditional 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, 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. 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.

  15. 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.

  16. Reflective Blankets Do Not Effect Cooling Rates after Running in Hot, Humid Conditions

    PubMed Central

    REYNOLDS, KORY A.; EVANICH, JOHN J.; EBERMAN, LINDSEY E.

    2015-01-01

    Reflective blankets (RB) are often provided at the conclusion of endurance events, even in extreme environments. The implications could be dangerous if increased core body temperature (CBT) is exacerbated by RB. To evaluate the effect of RB on cooling rate for individuals walking or sitting after intense running. Pilot, randomized control trial experimental design. Environmental chamber. Recreational runners (age=25±5y; mass=76.8±16.7kg; height=177±9cm) completed an 8km (actual mean distance=7.5±1.1km). We randomly assigned participants into one of four groups: walking with blanket (WB=5), walking without blanket (WNB=5), sitting with blanket (SB=5), or sitting without blanket (SNB=4). Participants ran on a treadmill at their own pace until volitional exhaustion, achieving the 8km distance, or experiencing CBT=40°C. Every three minutes during the running (time determined by pace) and cooling protocol (62 min in chamber), we measured CBT, HR, and Borg scale, and environmental conditions. We evaluated cooling rate, peak physiological variables, pace, and environment by condition using a Kruskal-Wallis non-parametric one-way ANOVAs. We identified similar exercise sessions (df=3; CBT χ2=0.921, p=0.82; HR χ2=7.446, p=0.06; Borg χ2= 5.732, p=0.13; pace χ2=0.747, p=0.86) and similar environmental characteristics between conditions (df=3; Wet Bulb Globe Temperature=26.18±2.78°C, χ2=1.552, p=0.67). No significant differences between conditions on cooling rate (df=3, χ2=2.301, p=0.512) were found, suggesting RBs neither cool nor heat the body, whether seated (SB=0.021±0.011deg/min; SNB=0.029±0.002deg/min) or walking (WB=0.015±0.025deg/min; WNB=0.021±0.011deg/min) in a hot, humid environment. CBT in distance runners is not altered by the use of a RB during a seated or walking cool down after a strenuous run. PMID:27182414

  17. 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.

  18. 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. PMID:27246375

  19. The development of ASTM standards for metallographic preparation practices of thermally sprayed coatings

    SciTech Connect

    Blann, G.A.; Diaz, D.J.

    1994-12-31

    The primary objective of metallographic examinations of thermally sprayed coatings is to reveal the constituents and structure of the coatings and substrates by means of the microscope after proper metallographic preparation is performed. Because of the diversity of coating types and the personal element, the standardization of metallographic preparation of thermally sprayed coatings is essential. An ASTM subcommittee was formed with the support of the ASM Thermal Spray Committee to provide the laboratories involved in coating characterization with guidelines that will provide consistent metallographic procedures that produce an accurate evaluation of the wide range of thermally sprayed coatings. The methods used to establish this standard will be discussed in this paper.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. Dynamics of cryogen deposition relative to heat extraction rate during cryogen spray cooling

    NASA Astrophysics Data System (ADS)

    Verkruysse, Wim; Majaron, Boris; Aguilar, Guillermo; Svaasand, Lars O.; Nelson, J. Stuart

    2000-05-01

    Goal is to investigate how delivery nozzle design influences the cooling rate of cryogen spray as used in skin laser treatments. Cryogen was sprayed through nozzles that consist of metal tubes with either a narrow or wide diameter and two different lengths. Fast-flashlamp photography showed that the wide nozzles, in particular the long wide one, produced a cryogen jet (very small spray cone angle) rather than a spray (cone angles of about 15 degrees or higher) and appeared to atomize the cryogen less finely than the narrow nozzles. We measured the cooling rate by spraying some cryogen on an epoxy-block with thermocouples embedded. The heat extraction rate of the wide nozzles was higher than that of the narrow nozzles. The results suggest that finely atomized droplets produced by the narrow nozzles do not have enough kinetic energy to break through a layer of liquid cryogen accumulated on the object, which may act as a thermal barrier and, thus, slow down heat extraction. Presumably, larger droplets or non- broken jets ensure a more violent impact on this layer and therefore ensure an enhanced thermal contact. The margin of error for the heat extraction estimate is analyzed when using the epoxy-block. We introduce a complementary method for estimating heat extraction rate of cryogen sprays.

  5. 70 FR 5483 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Cool Roof Rating...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2005-02-02

    ... National Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Cool Roof... principal place of business of the standards development organization is: Cool Roof Rating Council, Oakland... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of...

  6. 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.

  7. Cold {sup 52}Cr elastic and inelastic collision-rate determination using evaporative cooling analysis

    SciTech Connect

    Nguyen, Scott V.; Carvalho, Robert de; Doyle, John M.

    2007-06-15

    Elastic and inelastic collision-rate constants of {sup 52}Cr in the temperature range of 20 mK to 1 K are inferred from the evaporative cooling of buffer gas loaded atomic chromium. Using a model that describes the dynamics of the trapped chromium cloud during evaporation, we find g{sub el}=2.15(+2.5,-1.2)x10{sup -10} cm{sup 3}/s and g{sub in}=1.36(+1.2,-0.7)x10{sup -12} cm{sup 3}/s, consistent with theory but in disagreement with previously reported measurements.

  8. 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.

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

    DOE PAGESBeta

    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.

  10. Calculation of the gain coefficient in cryogenically cooled Yb : YAG disks at high heat generation rates

    SciTech Connect

    Vadimova, O L; Mukhin, I B; Kuznetsov, I I; Palashov, O V; Perevezentsev, E A; Khazanov, Efim A

    2013-03-31

    We have calculated the stored energy and gain coefficient in disk gain elements cooled to cryogenic temperatures. The problem has been solved with allowance for intense heat generation, amplified spontaneous emission and parasitic lasing, without averaging over any spatial coordinate. The numerical simulation results agree well with experimental data, in particular at high heat generation rates. Experimental data and theoretical analysis indicate that composite disk gain elements containing an undoped region can store considerably more energy due to suppression of amplified spontaneous emission and parasitic lasing. (extreme light fields and their applications)

  11. 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.

  12. The Effect of Cooling Rate, and Cool Deformation Through Strain-Induced Transformation, on Microstructural Evolution and Mechanical Properties of Microalloyed Steels

    NASA Astrophysics Data System (ADS)

    Mousavi Anijdan, S. H.; Yue, Steve

    2012-04-01

    In this article, a detailed study was conducted to evaluate the microstructural evolution and mechanical properties of microalloyed steels processed by thermomechanical schedules incorporating cool deformation. Cool deformation was incorporated into a full scale simulation of hot rolling, and the effect of prior austenite conditioning on the cool deformability of microalloyed steels was investigated. As well, the effect of varying cooling rate, from the end of the finishing stage to the cool deformation temperature, 673 K (400 °C), on mechanical properties and microstructural evolution was studied. Transmission electron microscopy (TEM) analysis, in particular for Nb containing steels, was also conducted for the precipitation evaluation. Results show that cool deformation greatly improves the strength of microalloyed steels. Of the several mechanisms identified, such as work hardening, precipitation, grain refinement, and strain-induced transformation (SIT) of retained austenite, SIT was proposed, for the first time in microalloyed steels, to be a significant factor for strengthening due to the deformation in ferrite. Results also show that the effect of precipitation in ferrite for the Nb bearing steels is greatly overshadowed by SIT at room temperature.

  13. 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.

    1999-01-01

    Lofgren (1989) and the further analysis of Lofgren's 1989 experiments by Jones and Lofgren (1993) established that cooling rates as slow as 5 C/hour produced analog textures and major and minor element zoning profiles in minerals, implying that a lower limit on chondrule cooling rate may be approximately 5 C/hour These results, however, are in conflict with those reported by Radomsky and Hewins (1990). In their paper, Radomsky and Hewins (1990) established a lower limit on chondrule cooling rates of I 100 C/hour a factor of 20 higher than that suggested by Jones and Lofgren (1993). The higher cooling rates suggested by Radomsky and Hewins (1990) have gained considerable favor within the meteoritic community largely because it appears more consistent with the preservation of Na in chondrules, which tends to volatilize at the slower cooling rates. In their study, however, Radomsky and Hewins (1990) did not use Pt hang wires that were coated or saturated with Fe. The lack of such techniques likely facilitated Fe loss from their experimental chondrules to the hang wire during formation (Jones and Lofgren, 1993). The effect of Fe loss could produce an inaccurate determination of cooling rates since these rates are largely determined by the Mg-Fe distributions in individual crystals.

  14. The Cooling Rate of an Active Aa Lava Flow Determined Using an Orbital Imaging Spectrometer

    NASA Astrophysics Data System (ADS)

    Wright, Robert; Garbeil, Harold

    2010-05-01

    The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer, are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing-1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4-2.5 micron region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wavebands available allows for the assumption of more complex flow surface temperature distributions in the radiance-to-temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well characterized calibration target. We then go on to demonstrate how this approach can be used to constrain the surface cooling rate of an active lava flow at Mount Etna, Sicily, using three images acquired during a four day period in September 2004. The cooling rate of the active channel as determined from space falls within the limits commonly assumed in numerical lava flow models. The results provide insights into the temperature-radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. Very narrow band model calculations of atmospheric fluxes and cooling rates

    SciTech Connect

    Bernstein, L.S.; Berk, A.; Acharya, P.K.; Robertson, D.C.

    1996-10-15

    A new very narrow band model (VNBM) approach has been developed and incorporated into the MODTRAN atmospheric transmittance-radiance code. The VNBM includes a computational spectral resolution of 1 cm{sup {minus}1}, a single-line Voigt equivalent width formalism that is based on the Rodgers-Williams approximation and accounts for the finite spectral width of the interval, explicit consideration of line tails, a statistical line overlap correction, a new sublayer integration approach that treats the effect of the sublayer temperature gradient on the path radiance, and the Curtis-Godson (CG) approximation for inhomogeneous paths. A modified procedure for determining the line density parameter 1/d is introduced, which reduces its magnitude. This results in a partial correction of the VNBM tendency to overestimate the interval equivalent widths. The standard two parameter CG approximation is used for H{sub 2}O and CO{sub 2}, while the Goody three parameter CG approximation is used for O{sub 3}. Atmospheric flux and cooling rate predictions using a research version of MODTRAN, MODR, are presented for H{sub 2}O (with and without the continuum), CO{sub 2}, and O{sub 3} for several model atmospheres. The effect of doubling the CO{sub 2} concentration is also considered. These calculations are compared to line-by-line (LBL) model calculations using the AER, GLA, GFDL, and GISS codes. The MODR predictions fall within the spread of the LBL results. The effects of decreasing the band model spectral resolution are illustrated using CO{sub 2} cooling rate and flux calculations. 36 refs., 18 figs., 1 tab.

  2. Influence of postexercise cooling techniques on heart rate variability in men.

    PubMed

    Leicht, Anthony S; Sinclair, Wade H; Patterson, Mark J; Rudzki, Stephan; Tulppo, Mikko P; Fogarty, Alison L; Winter, Sue

    2009-06-01

    The reduction of core body temperature (T(C)) is vitally important in the treatment of hyperthermia; however, little is known regarding the impact of cooling treatments on the autonomic control of heart rate (HR). The aim of the present study was to examine the influence of three field-based hyperthermia treatments on the neural control of HR via heart rate variability (HRV). Following exercise-induced hyperthermia (T(C) approximately 40.0 degrees C) in a warm environment (34.2 +/- 0.5 degrees C), nine healthy, active men were treated during recovery, in a randomized order, with intravenous cold saline infusion (IV) or ice packs (ICE) or fan cooling with intermittent water spray (FAN) for 40 min. During each treatment, HR dynamics via power spectral (VLF, LF, HF), Poincare plot (SD1, SD2), approximate entropy (ApEn) and short- (alpha(1)) and long-term (alpha(2)) fractal scaling analyses were determined every 10 min. At recovery onset, HR and T(C) were similar between treatments and were significantly reduced over the 40 min recovery period. During recovery, HR and alpha(2) were significantly reduced from initial levels but were significantly greater for IV compared with ICE and FAN. In contrast, VLF, LF, HF, SD1, SD2 and ApEn increased during recovery, with all being significantly lower for IV compared with ICE and/or FAN. The present results demonstrated that IV, compared with ICE and FAN, resulted in significantly greater HR, reduced spectral and geometrical HRV, lower HR complexity and reduced long-term HR control, indicative of reduced vagal and/or increased sympathetic modulation. Specific treatments for exercise-induced hyperthermia may result in an altered sympathovagal balance that requires further examination. PMID:19270035

  3. Extending the life of a Bausch and Lomb Research II metallograph

    SciTech Connect

    Crouse, R.S.

    1988-01-01

    The Bausch and Lomb Research II metallograph has been out of production for several years and objective lenses are becoming impossible to get. As lenses become damaged and unavailable, the usefulness of an otherwise fine instrument drops to zero. A successful attempt to retrofit Nikon lenses to a research II has been made. Mechanical modifications to the metallograph were easily accomplished by an experienced service man using the machine shop facilities available. The resulting modifications have restored the usefulness of our metallograph beyond expectations, and provided us with a viable means of maintaining it in sevice for many years to come.

  4. Cooling rate effects on the structure and transformation behavior of Cu-Zn-Al shape memory alloys

    NASA Astrophysics Data System (ADS)

    Lohan, Nicoleta-Monica; Suru, Marius-Gabriel; Pricop, Bogdan; Bujoreanu, Leandru-Gheorghe

    2014-11-01

    Different fragments of a hot-rolled and homogenized Cu-Zn-Al shape memory alloy (SMA) were subjected to thermal cycling by means of a differential scanning calorimetric (DSC) device. During thermal cycling, heating was performed at the same constant rate of increasing temperature while cooling was carried out at different rates of decreasing temperature. For each cooling rate, the temperature decreased in the same thermal interval. During each cooling stage, an exothermic peak (maximum) was observed on the DSC thermogram. This peak was associated with forward martensitic transformation. The DSC thermograms were analyzed with PROTEUS software: the critical martensitic transformation start (Ms) and finish (Mf) temperatures were determined by means of integral and tangent methods, and the dissipated heat was evaluated by the area between the corresponding maximum plot and a sigmoid baseline. The effects of the increase in cooling rate, assessed from a calorimetric viewpoint, consisted in the augmentation of the exothermic peak and the delay of direct martensitic transformation. The latter had the tendency to move to lower critical transformation temperatures. The martensite plates changed in morphology by becoming more oriented and by an augmenting in surface relief, which corresponded with the increase in cooling rate as observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM).

  5. 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.

  6. Cooling rate effect on outgrowth of Clostridium perfringens in cooked, ready-to-eat turkey breast roasts.

    PubMed

    Steele, F M; Wright, K H

    2001-06-01

    The potential for Clostridium perfringens spores to germinate and grow in cooked, ready-to-eat turkey products was evaluated to determine a safe cooling rate within the critical temperatures of 48.9 C (120 F) through 12.8 C (55 F). Raw turkey deli breast roasts were inoculated with a cocktail of C. perfringens spores (NCTC 8238, NCTC 8239, and NCTC 10388) and cooked in a steam oven to an internal temperature of 72 C. The sample roasts were then cooled through the critical cooling range at rates yielding cooling times of 6, 8, and 10 h. Turkey roasts were analyzed for spore growth and multiplication using tryptose-sulfite-cycloserine agar and anaerobic incubation at 37 C for 48 h. Cooling times of 6 and 8 h showed no proliferation of C. perfringens that would violate the USDA/Food Safety Inspection Service safe cooling standard criteria, which would allow no more than a 1 log10 multiplication between 48.9 and 12.8 C. A 9.6-h cooling period between the designated temperatures at a 95% confidence interval was determined to be adequate for nonproliferation of C. perfringens. On the other hand, a 95% tolerance interval would be more stringent in that it suggests no more than an 8.9-h cooling period. Tolerance intervals required that 95% of all our observations did not exceed the limit of 1 log10 increase in C. perfringens. This study indicated that in cooked, ready-to-eat turkey deli breasts, a cooling period between 48.9 C (120 F) and 12.8 C (55 F) of no greater than 8.9 h should be utilized to prevent possible C. perfringens foodborne outbreaks. PMID:11441851

  7. 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

  8. Effects of Cooling Rate on the Microstructure and Morphology of Sn-3.0Ag-0.5Cu Solder

    NASA Astrophysics Data System (ADS)

    Lee, Hwa-Teng; Huang, Kuo-Chen

    2016-01-01

    This study explored the effect of the cooling rate on the microstructure and morphology of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder. In the experiments, rapid cooling (P1: 63.17°C/s) of SAC305 solder resulted in high tensile strength (60.8 MPa) with no significant loss in ductility (strain >40%) due to the formation of fine-grained primary β-Sn (average size ˜14 μm) surrounded by a network-like fine eutectic structure consisting of β-Sn and particle-like Ag3Sn compound. As the cooling rate was reduced, the morphology of the Ag3Sn compound evolved progressively from a particle- to a needle-like form and finally to a leaf- or plate-like form. The cooling rate significantly affected the β-Sn grain size and the morphology of the Ag3Sn compound. Water cooling (at the fastest cooling rate of 100°C/s) of a solder sample resulted in a microstructure consisting of the finest structure of Ag3Sn and β-Sn with no Cu6Sn5, consequently exhibiting the highest hardness of the various specimens. By contrast, after cooling at the slowest rate of 0.008°C/s, the sample exhibited a coarse eutectic structure consisting of large plate-like Ag3Sn compound and isolated long rod-like Cu6Sn5 precipitates. This coarse structure resulted in both lower hardness and poorer tensile strength.

  9. 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.

  10. Effect of the rate of cooling on the phase composition of rare-earth titanates

    SciTech Connect

    Azimov, S.A.; Gulamova, D.D.; Suleimanov, S.Kh.

    1988-04-01

    The purpose of this work was to investigate the effect of different regimes of quenching with cooling rates of approx. 10/sup 2/ and 10/sup 5/ K/sec on the phase composition of rare-earth mono- and dititanates, as well as the possibility of formation of glasses at the nonvariant points (eutectic and peritectic) of the binary systems TiO/sub 2/-Ln/sub 2/O/sub 3/ (Ln-La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc). For compounds of the types Ln/sub 2/TiO/sub 5/ and Ln/sub 2/Ti/sub 2/O/sub 7/ (Ln-La...Lu, Y, Sc) there is a tendency for a structure with a higher symmetry to form as the ionic radius of the lanthanide decreases and the rate of quenching increases. The use of ultrarapid quenching expanded the region of existence of the cubic structure of the fluorite type to Tb/sub 2/TiO/sub 5/ and the structure of the pyrochlore type up to Sm/sub 2/Ti/sub 2/O/sub 7/. Ultrarapid quenching of compounds with the composition Ln/sub 4/Ti/sub 9/O/sub 24/ led to a transition into the amorphous state.

  11. 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.

  12. Effects of Treatment Duration and Cooling Rate on Pure Aluminum Solidification Upon Pulse Magneto-Oscillation Treatment

    NASA Astrophysics Data System (ADS)

    Edry, Itzhak; Mordechai, Tomer; Frage, Nachum; Hayun, Shmuel

    2016-03-01

    The effect of pulse magneto-oscillation (PMO) treatment on casting grain size has been widely investigated. Nevertheless, its mechanism remains unclear, especially when PMO is applied at different periods during solidification, namely when only applied above the melting point. In the present work, the effect of PMO treatment applied at different segments during solidification was investigated. It was found that the dendrite fragmentation model may well explain the effect of PMO applied during the dendrite growth stage. However, only the cavities activation model may account for the effect when PMO is conducted above the melting point. In current study, the effect of PMO treatment on grain size was also investigated at various cooling rates. It was established that the cooling rate had only a slight effect on grain size when PMO treatment was applied. Thus, PMO treatment may provide homogeneous grain size distribution in castings with different wall thicknesses that solidified with various cooling rates.

  13. 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.

  14. 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

  15. Cooling rate optimization for zebrafish sperm cryopreservation using a cryomicroscope coupled with SYBR14/PI dual staining.

    PubMed

    Bai, Chenglian; Wang, Xiaohua; Lu, Gang; Wei, Lindan; Liu, Kai; Gao, Hui; Huang, Changjiang; Dong, Qiaoxiang

    2013-10-01

    The Zebrafish has gained increased popularity as an aquatic model species in various research fields, and its widespread use has led to numerous mutant strains and transgenic lines. This creates the need to store these important genetic materials as frozen gametes. Sperm cryopreservation in zebrafish has been shown to yield very low post-thaw survival and many protocols suffer from great variability and poor reproducibility. The present study was intended to develop a freezing protocol that can be reliably used to cryopreserve zebrafish sperm with high post-thaw survival. In particular, our study focused on cooling protocol optimization with the aid of cryomicroscopy. Specifically, sperm suspended in 8% DMSO or 4% MeOH were first incubated with live/dead fluorescent dyes (SYBR14/PI) and then cooled at various rates from 4°C to different intermediate stopping temperatures such as -10, -20, -30 and -80°C before rewarming to 35°C at the rate of 100°C/min. %PI-positive (dead) cells were monitored throughout the cooling process and this screening yielded an optimal rate of 25°C/min for this initial phase of freezing. We then tested the optimal cooling rate for the second phase of freezing from various intermediate stopping temperatures to -80°C before plunging into liquid nitrogen. Our finding yielded an optimal intermediate stopping temperature of -30°C and an optimal rate of 5°C/min for this second phase of freezing. When we further applied this two-step cooling protocol to the conventional controlled-rate freezer, the average post-thaw motility measured by CASA was 46.8 ± 6.40% across 11 males, indicating high post-thaw survival and consistent results among different individuals. Our study indicates that cryomiscroscopy is a powerful tool to devise the optimal cooling conditions for species with sperm that are very sensitive to cryodamage. PMID:23747540

  16. Estimation of the fragility index of indomethacin by DSC using the heating and cooling rate dependency of the glass transition.

    PubMed

    Ramos, Joaquim J Moura; Taveira-Marques, Raquel; Diogo, Hermínio P

    2004-06-01

    In this study we have investigated the features of the glass transition relaxation of indomethacin using Differential Scanning Calorimetry (DSC). The purpose of this work is to provide an estimation of the activation energy at the glass transition temperature, as well as of the fragility index, of amorphous indomethacin from DSC data. To do so, the glass transition temperature region of amorphous indomethacin was characterized in both cooling and heating regimes. The activation energy for structural relaxation (directly related to glass fragility) was estimated from the heating and cooling rate dependence of the location of the DSC profile of the glass transition. The obtained results were similar in the heating and in the cooling modes. The results on the fragility index of indomethacin obtained in the present study, m = 60 in the cooling mode and m = 56 in the heating mode, are compared with other values previously published in the literature. PMID:15124208

  17. Cooling rates of living and killed chicken and quail eggs in air and in helium-oxygen gas mixture.

    PubMed

    Tazawa, H; Turner, J S; Paganelli, C V

    1988-01-01

    1. In a helium atmosphere, heat is dissipated from a surface 3.5 times faster than it is in air. Eggs in a helium-oxygen atmosphere cool only 1.4 times faster than they cool in air. This signifies that internal resistance to heat flow is a significant factor in the cooling rates of eggs. 2. Heat flow occurs inside an egg in two ways: by conduction through the tissues and in flowing blood. Killing an embryo stops the latter, but not the former. Eggs cool more slowly after they have been killed, signifying that blood flow can be an important component in an egg's internal flows of heat. 3. Blood flow should be a relatively more important component of heat flow in large eggs than in small eggs. The difference in conductance between living and killed eggs is larger in 60 g chicken eggs than it is in 10 g quail eggs. PMID:2900113

  18. Rating procedure for mixed-air-source unitary air conditioners and heat pumps operating in the cooling mode

    SciTech Connect

    Domanski, P.A.

    1986-02-01

    A procedure is presented for rating split, residential air conditioners and heat pumps operating in the cooling mode that are made up of an evaporator unit combined with a condensing unit that has been rated under current procedures in conjunction with a different evaporator unit. The procedure allows calculation of capacity at the 95/sup 0/ F rating point and seasonal energy efficiency ratio, SEER, without performing laboratory tests of the complete system.

  19. 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.

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

    USGS Publications Warehouse

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

    1990-01-01

    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. 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. -from Authors

  1. 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

  2. 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

  3. 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...

  4. 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.

  5. Time-temperature-sensitization diagrams and critical cooling rates of different nitrogen containing austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Parvathavarthini, N.; Dayal, R. K.

    2010-04-01

    Nitrogen-alloyed 316L stainless steel is being used as structural material for high temperature fast breeder reactor components with a design life of 40 years. With a view to increase the design life to 60 years and beyond, high nitrogen stainless steels are being considered for certain critical components which may be used at high temperatures. Since carbon and nitrogen have major influence on the sensitization kinetics, investigations were carried out to establish the sensitization behaviour of four heats of 316L SS containing (i) 0.07%N and 0.035%C, (ii) 0.120%N and 0.030%C, (iii) 0.150%N and 0.025%C and (iv) 0.22%N and 0.035%C. These stainless steels were subjected to heat treatments in the temperature range of 823-1023 K for various durations ranging from 1 h to 500 h. Using ASTM standard A262 Practice A and E tests, time-temperature-sensitization diagrams were constructed and from these diagrams, critical cooling rate above which there is no risk of sensitization was calculated. The data established in this work can be used to select optimum heat treatment parameters during heat treatments of fabricated components for fast reactors.

  6. 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.

  7. 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.

  8. 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.

  9. Thermal and structural behavior of milk fat. 3. Influence of cooling rate and droplet size on cream crystallization.

    PubMed

    Lopez, Christelle; Bourgaux, Claudie; Lesieur, Pierre; Bernadou, Sophie; Keller, Gérard; Ollivon, Michel

    2002-10-01

    Crystallization of triacylglycerols (TG) within milk fat globules of creams is studied with an instrument coupling time-resolved synchrotron X-ray diffraction (XRDT) at both small and wide angles and high-sensitivity differential scanning calorimetry (DSC) at cooling rates of -3 and -1 degrees C/min from 60 to -10 degrees C and compared to that of the anhydrous milk fat (AMF). Simultaneous thermal analysis permits correlation of the formation of the different crystalline species monitored by XRDT to the DSC events. Under the above cooling conditions, milk fat TG sequentially crystallize, within the globules, from about 19 degrees C, in three different lamellar structures with double-chain length (2L) stackings of 47 and 42 A and a triple-chain length (3L) stacking of 71 A, all of alpha type, which are correlated to two or three overlapped exothermic peaks recorded by DSC. Compared to what is observed for AMF, TG crystallization in emulsion (i) favors sub-alpha formation at low temperature and (ii) induces layer stacking defects in 3L crystals. Subsequent heating at 2 degrees C/min shows numerous structural rearrangements before final melting, confirming that (i) cooling at -1 degrees C/min leads to the formation of unstable crystalline varieties in the dispersed state and (ii) a monotropic transition alpha-->beta' takes place. Similar behavior is observed for cooling at -3 degrees C/min and subsequent heating. An overall comparison of the thermal and structural properties of the crystalline species formed as a function of the cooling rate, between >1000 and 0.15 degrees C/min, and stabilization time at 4 degrees C is given. Depending on the cooling rate, at least five crystalline subcell species are observed at wide angles, alpha and sub-alpha, two beta' and one beta. At small angles, at least six lamellar stackings are identified, three 3L and three 2L. However, a single subcell packing (e.g., alpha) might correspond to several longitudinal chain stackings

  10. 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.

  11. 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.

  12. Effect of cooling rate on magnetostriction gradients of Tb0.27Dy0.73Fe1.95 alloys solidified in high magnetic field gradients

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Gao, Peng-Fei; Dong, Meng; Xiao, Yu-Bao; Wang, Qiang

    2016-05-01

    In this work, Tb0.27Dy0.73Fe1.95 alloys were solidified in a high magnetic field gradient (8.8 T, -565 T2/m) at various cooling rates. Changes in the magnetostriction, crystal orientation, and magnetization of the alloys were investigated. The application of the magnetic field gradient has a strong influence on the magnetostrictive performance. At lower cooling rates, the maximum magnetostriction increases gradually with depth from the top surface of the alloys. However, the effect of the magnetic field gradient is strongly dependent on the cooling rate. With increasing cooling rate, the magnetostriction gradient decreases. The magnetization measurement shows that the saturation magnetization at lower cooling rates increases gradually with depth from the top surface of the alloys. However, with increasing cooling rate, the increase in the saturation magnetization is reduced. The XRD measurement results show that the orientation behavior of the (Tb, Dy)Fe2 phase exhibits a continuous change throughout the alloys at lower cooling rates, but is almost unchanged at higher cooling rates. The change in the magnetostriction of the alloys can be attributed to the changes in crystal orientation and the amount of the (Tb, Dy)Fe2 phase in the alloys caused by both the magnetic field gradient and cooling rate.

  13. 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.

  14. 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.

  15. Kinetics of Fe2+-Mg order-disorder in orthopyroxene: experimental studies and applications to cooling rates of rocks

    NASA Astrophysics Data System (ADS)

    Stimpfl, M.; Ganguly, J.; Molin, G.

    2005-10-01

    We determined the forward rate constant (K+) for the Fe2+-Mg order-disorder between the M2 and M1 sites of orthopyroxene (OPx), which is described by the homogeneous reaction Fe2+ (M2) + Mg(M1) ↔ Mg(M2) + Fe2+ (M1), by both ordering and disordering experiments at isothermal condition and also by continuous cooling experiments. The rate constant was determined as a function of temperature in the range of 550-750°C, oxygen fugacity between quartz-fayalite-iron and Ni-NiO buffers, and at compositions of 16 and 50 mol% ferrosilite component. The K+ value derived from disordering experiment was found to be larger than that derived from ordering experiment at 550°C, while at T>580°C, these two values are essentially the same. The fO2 dependence of the rate constant can be described by the relation K+ α (fO2) n with n=5.5-6.5, which is compatible with the theoretically expected relation. The Arrhenius relation at the WI buffer condition is given by ln (C_{text{o}} {text{K}}^+) = - {41511 - 12600{text{X}}_{{text{Fe}}} }/{{T({text{K}})}} + 28.26 + 5.27{text{X}}_{{text{Fe}}}, min^{-1} where C o represents the total number of M2 + M1 sites occupied by Fe2+ and Mg per unit volume of the crystal. The above relation can be used to calculate the cooling rates of natural OPx crystals around the closure temperature ( T c) of Fe-Mg ordering, which are usually below 300°C for slowly cooled rocks. We determined the Fe-Mg ordering states of several OPx crystals (˜ Fs50) from the Central Gneissic Complex (Khtada Lake), British Columbia, which yields T c ˜290°C. Numerical simulation of the change of Fe2+-Mg ordering in OPx as a function of temperature using the above expression of rate constant and a non-linear cooling model yields quenched values of ordering states that are in agreement with the observed values for cooling rates of 11-17°C/Myr below 300°C. The inferred cooling rate is in agreement with the available geochronological constraints.

  16. 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.

  17. 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.

  18. Comparison of band model calculations of upper atmospheric cooling rates for the 15-micrometer carbon dioxide band

    NASA Technical Reports Server (NTRS)

    Boughner, R. E.

    1985-01-01

    Within the atmosphere of the earth, absorption and emission of thermal radiation by the 15-micron CO2 bands are the largest contributors to infrared cooling rates in the stratosphere. Various techniques for calculating cooling rates due to these bands have been described. These techniques can be classified into one of two categories, including 'exact' or line-by-line calculations and other methods. The latter methods are based on broad band emissivity and band absorptance formulations. The present paper has the objective to present comparisons of the considered computational approaches. It was found that the best agreement with the exact line-by-line calculations of Fels and Schwarzkopf (1981) could be obtained by making use of a new Doppler band model which is described in the appendix of the paper.

  19. Crystallization sequences of Ca-Al-rich inclusions from Allende - The effects of cooling rate and maximum temperature

    NASA Technical Reports Server (NTRS)

    Stolper, E.; Paque, J. M.

    1986-01-01

    The crystallization sequences, mineral chemistries, and textures resulting from the cooling in air from 1275-1580 C to below 100 C at rates between 0.5 and 100 c/hr of an average Type B Ca-Al-rich inclusion composition are investigated. Comparison of experimental results with petrographic observations of Type B CaIs indicates that most inclusions were partially melted and then cooled at rates of the order of a few tenths to tens of degrees per hour, with maximum temperatures of about 1400 C suggested for intermediate Type B Allende inclusions. Data are consistent with the drag heating of particles falling though nebular gas, heating in nebular shock fronts, or other thermal heterogeneities in the early nebula allowing time scales for heating of CAIs much shorter than those for the nebular cloud as a whole.

  20. Effect of high-intensity ultrasound and cooling rate on the crystallization behavior of beeswax in edible oils.

    PubMed

    Jana, Sarbojeet; Martini, Silvana

    2014-10-15

    The objective of this study was to evaluate the effect of wax concentration (0.5 and 1%), cooling rate (0.1, 1, and 10 °C/min), and high-intensity ultrasound (HIU) on the crystallization behavior of beeswax (BW) in six different edible oils. Samples were crystallized at 25 °C with and without HIU. Crystal sizes and morphologies and melting profiles were measured by microscopy and differential scanning calorimetry, respectively, after 7 days of incubation. Higher wax concentrations resulted in faster crystallization and more turbidity. Phase separation was observed due to crystals' sedimentation when samples were crystallized at slow cooling rates. Results showed that HIU induced the crystallization of 0.5% BW samples and delayed phase separation in sunflower, olive, soybean, and corn oils. Similar effects were observed in 1% samples where HIU delayed phase separation in canola, soybean, olive, and safflower oils. PMID:25265535

  1. Effect of cooling rate on the microstructure and microhardness of the CuZrAgAl alloy

    SciTech Connect

    Liu, Y.; Blandin, J.J.; Suery, M.; Kapelski, G.

    2012-08-15

    The effect of cooling rate on the microstructure and microhardness of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} (at.%) alloy has been studied. The crystalline phases were characterized by X-ray diffraction, optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy, and identified as AlCu{sub 2}Zr, Cu{sub 10}Zr{sub 7} and CuZr{sub 2}. The solidification sequence was established as following: the Cu{sub 10}Zr{sub 7} phase forms first in the periphery of the rod, then following with AlCu{sub 2}Zr phase in the rod center and finally CuZr{sub 2} crystals in Cu-depleted areas. The effect of crystals on the mechanical properties of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was also estimated through the microhardness. According to the value of microhardness, inhomogeneous structure of the amorphous matrix is more easily formed for the alloy in the low cooling rate (i.e., 9 mm) as compared with the alloy with fully amorphous state in the large cooling rate (i.e., 3 mm). This inhomogeneous structure was attributed to the composition change of amorphous matrix arising from the forming of crystalline phases due to the low cooling rate. - Highlights: Black-Right-Pointing-Pointer The crystalline phases in the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy were identified. Black-Right-Pointing-Pointer The solidification sequence of Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was verified. Black-Right-Pointing-Pointer The softening and hardening of alloy could be observed due to the crystallization.

  2. 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.

  3. Effects of Annealing Cool-down Rate on Torque Transducer Response Function in 4340 High-Alloy Steel

    NASA Astrophysics Data System (ADS)

    Hecox, Bryan G.; Wiewel, Joseph L.; Boley, Mark S.

    2007-03-01

    We have investigated the change in magnetoelastic torque transducer response as the annealing cool-down rate is changed in 4340 high-alloy steel. In many commercial power-train applications, measurement of torque via a non-contact method is highly desirable. Three separate solid steel 1-inch diameter shafts underwent a common hardening process conducted in a helium atmosphere followed by a five hour annealing process at 843^o C. Subsequently, the three samples were cooled down at rates of 10^o C, 15^o C, and 20^o C, respectively. Prior and subsequent to heat treatment, the axial magnetic hysteresis properties of the samples were measured and their external field signals were mapped over the magnetically polarized regions both with and without torque (applied shear stress up to 3500 psi). The faster annealing cool-down rate increased the torque response (sensitivity) and the field map height the most. The heat treatment improved the Gaussian field map shape and removed the remnants of old domain walls. Linearity of response remained consistent before and after heat treatment.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Effect of time of progesterone supplementation on serum progesterone and the conception rate of cooled Holstein heifers during the summer.

    PubMed

    Correa-Calderón, Abelardo; Pérez-Velázquez, Rolando; Avendaño-Reyes, Leonel; Macias-Cruz, Ulises; Diaz-Molina, Raúl; Rivera-Acuña, Fernando

    2016-06-01

    To investigate the effects of progesterone supplementation at two different times on serum progesterone (P4 ) concentration, conception rate and resynchronization of cooled Holstein heifers in summer, 90 heifers were randomly assigned to two groups: (i) heifers subjected to TAI (timed artificial insemination) and progesterone supplementation from days 4 to 14 after TAI (S1; n = 45); and (ii) heifers under the same TAI protocol as S1 and progesterone supplementation from days 17 to 22 after TAI (S2 ; n = 45). The groups S1 and S2 were cooled 10 days before and 21 days after TAI. Respiratory rate, body surface temperature, vaginal temperature and rectal temperature recorded during the experiment were not different (P > 0.05) between S1 and S2 groups. Progesterone concentration was not different (P > 0.05) in S1 compared to S2 . The conception rates on days 30 and 55 were similar between groups (P > 0.05). Progesterone supplementation did not increase either conception rate or concentrations of P4 in heifers during the summer. Heifers not pregnant to first service in the group S2 were resynchronized (77.7%) for a second breeding. PMID:26302978

  11. 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

  12. 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.

  13. 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.

  14. Influence of NaCl content and cooling rate on outgrowth of Clostridium perfringens spores in cooked ham and beef.

    PubMed

    Zaika, Laura L

    2003-09-01

    The effect of NaCl concentration and cooling rate on the ability of Clostridium perfringens to grow from spore inocula was studied with the use of a process that simulates the industrial cooking and cooling of smoked boneless ham and beef roasts. NaCl was added to ground cooked hams A and B (which were commercially obtained) to obtain levels of 2.4, 3.1, 3.6, and 4.1% (wt/wt) and 2.8, 3.3, 3.8, and 4.3% (wt/wt), respectively, and to raw ground beef to obtain levels of 0, 1, 2, 3, and 4% (wt/wt). Ham C, a specially formulated, commercially prepared product, was supplemented with NaCl to obtain levels of 2.0, 2.5, 3.0, and 3.5%. The samples were inoculated with a three-strain mixture of C. perfringens spores to obtain concentrations of ca. 3 log10 CFU/g. Portions of meat (5 g each) were spread into thin layers (1 to 2 mm) in plastic bags, vacuum packaged, and stored at -40 degrees C. Thawed samples were heated at 75 degrees C for 20 min and subsequently cooled in a programmed water bath from 54.4 to < or = 8.5 degrees C in 15, 18, or 21 h. For the enumeration of C. perfringens, samples were plated on tryptose-sulfite-cycloserine agar and incubated in an anaerobic chamber at 37 degrees C for 48 h. Population densities for cooked ham and beef increased as cooling time increased, and NaCl exerted a strong inhibitory effect on the germination and outgrowth of C. perfringens. For beef, while 3% NaCl completely arrested growth, pathogen numbers increased by > or = 3, 5, and 5 log10 CFU/g in 15, 18, and 21 h, respectively, when the NaCl level was <2%. C. perfringens did not grow during cooling for 15, 18, or 21 h in ham samples containing > or = 3.1% NaCl. Results obtained in this study suggest that a 15-h cooling time for cooked ham, which is normally formulated to contain >2% NaCl, would yield an acceptable product (with an increase of <1 log10 CFU/g in the C. perfringens count); however, for beef containing <2% NaCl, C. perfringens populations may reach levels high

  15. 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.

  16. Critical cooling and warming rates to avoid ice crystallization in small pieces of mammalian organs permeated with cryoprotective agents.

    PubMed

    Peyridieu, J F; Baudot, A; Boutron, P; Mazuer, J; Odin, J; Ray, A; Chapelier, E; Payen, E; Descotes, J L

    1996-08-01

    Measurements were made by differential scanning calorimetry on small pieces of rabbit kidney permeated with 2, 3-butanediol containing mainly the levo- and dextro-isomers. The critical cooling rates necessary to vitrify the pieces of organ, and the corresponding critical warming rates which are required to avoid crystallization in the vitrified samples, were determined. The dynamic method used for these determinations is described. The glass-forming tendency and the stability of the amorphous state were both greater in the kidney tissue samples than in the bulk cryoprotective solution. This result is discussed in the context of the lowering of the freezing point of water in emulsions and the promotion of supercooling in hydrogels and porous materials. In corresponding experiments with rat hearts impregnated with 1,2-propanediol, only the critical warming rate was reduced. PMID:8764852

  17. 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

  18. Cut-off rate calculations for the outer channel in a concatenated cooling system

    NASA Technical Reports Server (NTRS)

    Herro, M. A.; Costello, D. J., Jr.; Hu, L.

    1984-01-01

    Concatenated codes were long used as a practical means of achieving long block or constraint lengths for combating errors on very noisy channels. The inner and outer encoders are normally separated by an interleaver, so that decoded error bursts coming from the inner decoder are randomized before entering the outer decoder. The effectiveness of this interleaver is examined by calculating the cut-off rate of the outer channel seen by the outer decoder with and without interleaving. Interleaving never hurts the performance of a concatenated code, and when the inner code rate is near the cut-off rate of the inner channel, interleaving significantly improves code performance.

  19. Cooling rate threshold in transformation of C_60 fullerene to amorphous diamond and highly disordered carbon in SCARQ experiments

    NASA Astrophysics Data System (ADS)

    Homae, Tomotaka; Okamoto, Atsushi; Nakamura, Kazutaka; Ken-Ichi, Kondo; Yoshida, Masatake; Hirabayashi, Keiji; Niwase, Keisuke

    2001-06-01

    Synthesis of amorphous diamond from C_60 fullerene by Shock compression and rapid quenching (SCARQ) technique was reported previously (Hirai et. al., Appl. Phys. Lett. 64, 1797 (1994)). In this paper, we report the condition for the formation of amorphous diamond. When the initial thickness was less than 10 μm, the recovered sample showed broad photoluminescence (PL) and cathodeluminescence (CL) spectra but no Raman peaks. These observations indicate that the sample was amorphous diamond. In the case of 20-μm thick sample, the recovered sample was disordered carbon as it gave G and D Raman peaks and PL spectrum. However, it gave CL spectrum similar to amorphous diamond, which is not normally observed for normal disordered carbon. The cooling rate related to the initial thickness of the sample was estimated by numerically calculated temperature changes of the sample on the basis of Fourier's law for conduction heat transfer. The threshold of cooling rate between amorphous diamond and disordered carbon was determined. The details of the transformation processes of C_60 fullerene will be discussed.

  20. Metallographic analysis and fire dynamics simulation for electrical fire scene reconstruction.

    PubMed

    Chi, Jen-Hao

    2012-01-01

    This study demonstrated the use of metallographic analysis and NIST's Fire Dynamics Simulator (FDS) program to identify the cause of an actual electrical fire. A severely carbonized steel plate and a cable with a bead were found inside a damaged switchboard from the debris of a factory fire. By metallographic analysis, the copper spatter on the steel plate was found to imply a short circuit has occurred and that this was the probable ignition source of the fire was supported by the presence of a small amount of copper oxide and by the cavities with the tree-like grain microstructures in the bead. The heat estimated to have been released per unit area of the switchboard in question (approximately 236.29 MJ/m(2)) served as key input data for applying the FDS simulation of the blaze. The simulation indicated that thermal insulation polyethylene (PE) played an important role in the rapid fire spread. PMID:22040381

  1. 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.

  2. Effect of cooling rates and temperatures on quality and safety of quahog clams (Mercenaria mercenaria).

    PubMed

    Granata, Linda Ankenman; Bourne, Dianne Wall; Flick, George J; Peirson, Michael; Riley, Tara; Croonenberghs, Robert E; Kensler, Jennifer

    2014-05-01

    The model ordinance in the National Shellfish Sanitation Program's Guide for the Control of Molluscan Shellfish was initially established for oysters; however, the clam industry also follows the protocol. Rapid cooling during periods when the growing waters exceed 80 °F (26.7 °C) results in cold shock, which causes unacceptable mortalities in clams. The clam industry was looking for a procedure to lower the clams to the standard temperature while minimizing shell shock mortalities during the warm summer months. Three tempering treatments were examined, and total aerobic plate counts (APCs) and most-probable-number (MPN) counts of Vibrio, V. parahaemolyticus, and fecal coliforms were enumerated. In treatment 1 (control), clams were harvested, held for 5 h at 90 °F (32.2 °C), and then moved to 45 °F (7.2 °C) for storage. In treatment 2, clams were harvested and held for 5 h at 90 °F (32.2 °C), followed by 12 h at 65 °F (18.3 °C) and 12 h at 55 °F (12.8 °C), and then were moved to 45 °F (7.2 °C) for long-term storage. In treatment 3, clams were harvested and held for 5 h at 90 °F (32.2 °C), followed by 24 h at 55 °F (12.8 °C) before being moved to 45 °F (7.2 °C) for long-term storage. Three replicate trials were performed with triplicate analyses during late June through early to mid-August. The current National Shellfish Sanitation Program standard is treatment 1; it contained statistically (P ≤ 0.05) higher total APCs than treatments 2 and 3 throughout the 21-day storage period. APCs ranged from 2.3 × 10(4) immediately after harvest to 2.7 × 10(6), 1.6 × 10(5), and 4.8 × 10(5) for treatments 1, 2, and 3, respectively, after 14 days of storage. A statistical analysis showed that treatments 2 and 3 had significantly lower total MPN per gram Vibrio than treatment 1 on day 7 but were equal to treatment 1 on days 1 and 14. MPN per gram for V. parahaemolyticus was statistically lower in treatments 2 and 3 than in treatment 1 on storage days 1 and

  3. Cooling rate of some active lavas determined using an orbital imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Wright, Robert; Garbeil, Harold; Davies, Ashley G.

    2010-06-01

    The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing-1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4-2.5 μm region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wave bands available allows for the assumption of more complex flow surface temperature distributions in the radiance-to-temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well-characterized calibration target, a time series of three Hyperion images of an active lava flow acquired during a 4 day period at Mount Etna, Sicily, as well as a lava flow erupted at Nyamuragira, Democratic Republic of Congo. The results provide insights into the temperature-radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission.

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

    DOE PAGESBeta

    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

  5. 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

  6. Meteoritic basalts: The nakhlites, their parental magmas, cooling rates, and equivalents on Earth

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1987-01-01

    Field study in northern Ontario was planned to compare cumulate rocks reported in the literature with the nakhlites in order to study the crystallization rates of the nakhlites and their possible geological settings. Experimental studies have progressed slowly because of the demands of the field work and teaching. The furnace is fully functional, and its thermocouple and oxygen sensor cells are functional and calibrated.

  7. 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.

  8. H-chondrite parent asteroid: A multistage cooling, fragmentation and re-accretion history constrained by thermometric studies, diffusion kinetic modeling and geochronological data

    NASA Astrophysics Data System (ADS)

    Ganguly, Jibamitra; Tirone, Massimiliano; Chakraborty, Sumit; Domanik, Kenneth

    2013-03-01

    We present a detailed thermometric study and cooling history analysis of selected H-chondrites from the petrologic types 4-6 on the basis of their mineralogical properties, and integrate these data with other available constraints on the cooling rates to develop a comprehensive model for the cooling, fragmentation and re-accretion history of the parent asteroid. Temperatures have been determined on the basis of two-pyroxene (2-Px) and spinel (Spnl)-orthopyroxene (Opx)/olivine (Ol) thermometers using the average of line scans and distributed spot analysis of coexisting pairs in each set. All of these minerals have been found to be compositionally homogeneous from ˜1 to 2 μm from the interface within the resolution of microprobe analysis. The thermometric results for the H5 (Allegan and Richardton) and H6 (Guarena and Kernouvé) samples are very similar. Also, while the 2-Px temperature increases by ˜90 °C from H4 to H5/6, a reverse trend is observed for the Spnl-Opx/Ol temperatures implying compositional resetting of these pairs during cooling. For the H4 sample (Forest Vale) all thermometric results are similar. The cooling rates calculated from numerical modeling of the compositional profiles in Opx-Cpx pairs in H5 and H6, corrected for the spatial averaging or convolution effect in microprobe analysis, are ˜25-100 °C/ky, which are 3-4 orders of magnitude higher than the cooling rates implied by in situ cooling in an onion-shell parent body model. Similar numerical simulation of the compositional profile in Opx-Spnl pair in H4 yields a cooling rate ˜50 °C/ky, which is in very good agreement with recent metallographic cooling rate of this sample and geochronological constraints on the cooling T-t path. Numerical simulation suggests that the slow cooling of the H5/6 samples at a rate of ˜15 °C/My, as deduced by recent metallographic study, could not have commenced at a temperature above ˜700 °C since, otherwise, the simulated compositional profile fails

  9. 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

  10. Effect of hot-rolling and cooling rate on microstructure and high-temperature strength in 9CrODS steel

    NASA Astrophysics Data System (ADS)

    Wu, XCH.; Ukai, S.; Miyata, R.; Oono, N.; Hayashi, S.; Leng, B.; Ohtsuka, S.; Kaito, T.

    2013-09-01

    The 9CrODS steel specimens were prepared by different processing with hot-rolling and different cooling rate. The hardness and high-temperature tensile properties were measured. Microstructure was analyzed by means of EBSD inverse pole figure and kernel average miss-orientation angles. The hot-rolled and then air-cooled specimen has the highest tensile strength. The furnace-cooled specimen also has better tensile strength at 700 °C than air-cooled specimen at normalized condition. The high-temperature strength of 9CrODS steel is significantly improved with increasing grain size that can be induced by hot-rolling or furnace-slow cooling, where the localized grain boundary deformation can be suppressed.

  11. 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. PMID:22434120

  12. 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.

  13. 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

    2016-06-01

    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.

  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. 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.

  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. PMID:27318716

  17. 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

  18. 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. PMID:22225685

  19. 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.

  20. Preliminary metallographic studies of ball fatigue under rolling-contact conditions

    NASA Technical Reports Server (NTRS)

    Bear, H Robert; Butler, Robert H

    1957-01-01

    The metallurgical results produced on balls tested in the rolling-contact fatigue spin rig were studied by metallographic examination. Origin and progression of fatigue failures were observed. These evaluations were made on SAE 52100 and AISI M-1 balls fatigue tested at room temperature (80 F) and 200 to 250 F. Most failures originated subsurface in shear; inclusions, structure changes, and directionalism adversely affected ball fatigue life. Structures in the maximum-shear-stress region of the balls of both materials were stable at room temperature and unstable at 200 to 250 F. Failures were of the same type as those found in full-scale bearings.

  1. 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.

  2. 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.

  3. 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.

  4. 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

    2016-04-01

    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.

  5. 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.

  6. Effect of composition, cooling rate, and solidification velocity on the microstructural development of molybdenum-bearing stainless steels

    NASA Astrophysics Data System (ADS)

    Perricone, Matthew J.

    A series of Mo-bearing stainless steel compositions ranging from 0 to 10 wt% Mo were analyzed over a range of laser welding conditions to evaluate the effect of composition, cooling rate, and solidification velocity on microstructural development. Of particular engineering interest are alloys expected to solidify as primary delta-ferrite and transform in the solid state to gamma-austenite. Such compositions are essentially immune to solidification cracking and can potentially eliminate microsegregation (due to primary ferrite solidification) while still having high toughness and no magnetic signature at room temperature (transformation to austenite). A total of 64 Fe-Ni-Cr-Mo compositions were chosen based on multi-component phase stability diagrams calculated using the CALPHAD method. Alloys were created using the arc button melting process and laser welds were prepared on each alloy at constant power and travel speeds ranging from 4.2 mm/s to 42 mm/s. The cooling rates of these processes were estimated to range from 10 °C/s for are buttons to 105 °C/s for the fastest laser welds. Microstructural analysis was completed to determine primary solidification mode and the nature of solid state transformation behavior. Good agreement was observed between experimental observations and predictions from thermodynamic calculations. No shift in solidification mode was observed from primary delta-ferrite to primary gamma-austenite in the range of welding conditions studied. Metastable microstructural features were observed in many laser weld fusion zones, as well as a massive transformation from delta-ferrite to gamma-austenite in many of the alloys exhibiting primary delta-ferrite solidification. Evidence of epitaxial massive growth without nucleation was also found in primary delta-ferrite alloys with intercellular gamma-austenite already present from a solidification reaction. The resulting single phase gamma-austenite in both cases exhibited a homogenous distribution of

  7. Metallographic evaluation of hip joint implants wear and electrochemical implants potential.

    PubMed

    Kmieć, Krzysztof; Sibinski, Marcin; Synder, Marek; Drobniewski, Marek; Kozłowski, Piotr

    2014-12-01

    We performed metallographic evaluations of implants, removed during revision hip arthroplasty. The implants were evaluated for electrochemical potentials and the presence of wear products on the implants surface. A total of 50 patients (50 hips) underwent revision hip arthroplasty during the years 2007-2009 for aseptic loosening. The mean follow-up from primary hip replacement to revision was 10.1 years (from six months to 17 years). All hip joint implants removed during the revision arthroplasty were submitted to metallographic analysis and all heads were submitted to analysis under a scanning microscope. All polyethylene (PE) cups and inserts showed numerous features of wear (friction wear, plastic deformation and creeping, fatigue wear and degradation), six PE cups were broken. In six ceramic cups, only friction wear features were found; one of them was mechanically broken. In all heads articulating on PE not one had any mechanical damage. Heads of ceramic implants in ceramic-ceramic articulation undergo abrasive wear. None of the studied stems (cemented or uncemented) revealed any features of wear. Areas of titanium crystals (formed by electrolytic sedimentation of metals) were macroscopically identified on the sliding surface of six heads that was confirmed by chemical composition and scanning microscope.In the course of prosthesis use, wear products are produced and transferred onto the sliding surfaces of implant heads and cups via ways other than purely mechanical contact. It has been confirmed that metals used for implant construction, make galvanic cells with different electrochemical potentials. PMID:25362874

  8. 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

  9. 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

  10. 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.

  11. Thorny devil nanotextured fibers: the way to cooling rates on the order of 1 kW/cm2.

    PubMed

    Sinha-Ray, S; Zhang, Y; Yarin, A L

    2011-01-01

    In the present work high-heat-flux surfaces, which should serve at temperatures of up to 200 °C, were covered by electrospun polymer nanofiber mats with thicknesses of about 30 μm. Then, four different metals were electroplated on separate polymer mats, namely, copper, silver, nickel, and gold. As a result, copper-plated nanofiber mats took on an appearance resembling that of a small Australian thorny devil lizard (i.e., they became very rough on the nanoscale) and acquired a high thermal diffusivity. Silver-plated nanofiber mats also became very rough because of the dendritelike and cactuslike nanostructures on their surfaces. However, nickel-plated nanofibers were only partially rough and their mats incorporated large domains of smooth nickel-plated fibers, and gold-plated nanofibers were practically smooth. Drop impacts on the hot surfaces coated with copper-plated and silver-plated nanofibers revealed tremendously high values of heat removal rates of up to 0.6 kW/cm(2). Such high values of heat flux are more than an order of magnitude higher that the currently available ones and probably can be increased even more using the same technique. They open some intriguing perspectives for the cooling of high-heat-flux microelectronics and optoelectronics and for further miniaturization of such devices, especially for such applications as UAVs and UGVs. PMID:21126096

  12. Investigation of the effects of cooling rate on the microstructure of investment cast biomedical grade Co alloys

    NASA Astrophysics Data System (ADS)

    Kaiser, R.; Browne, D. J.; Williamson, K.

    2012-01-01

    The objective of this work is to determine the microstructural characteristics of investment cast cobalt alloy as the cross-sectional area is varied, thus changing the local effective cooling rates and solidification times. The extent of published work on the as-cast properties of cobalt alloys is minimal. The primary aim of this work is therefore to extend knowledge of the behaviour of such alloys as they solidify, which will influence the design of new products as well as the industrial optimisation of the casting process. Wedge-shaped parts were cast from a biomedical grade cobalt alloy employing the method of lost wax investment casting. Analytical techniques such as optical microscopy, image analysis and microhardness testing were used to characterise the as-cast parts. Parameters studied include variations in grain structure, nature of the columnar and equiaxed zones and the spread of porosity (both shrinkage and gas). Changes in microstructure were compared to microhardness values obtained. The solidification profile of the alloy through the prototype cast component was investigated based on measurement of the dendrite arm spacings. A discussion on the physical phenomena controlling the microstructural variations is presented.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. A slow cooling rate of indomethacin melt spatially confined in microcontainers increases the physical stability of the amorphous drug without influencing its biorelevant dissolution behaviour.

    PubMed

    Nielsen, Line Hagner; Keller, Stephan Sylvest; Boisen, Anja; Müllertz, Anette; Rades, Thomas

    2014-06-01

    Amorphous indomethacin was prepared by melting the γ-form of indomethacin, spatially confined within microcontainers (inner diameter of 223 μm), followed by cooling of the melt at a rate of 14, 23 or 36 K/min. The physical stability of the amorphous indomethacin within microcontainers was investigated using Raman microscopy. Furthermore, the dissolution behaviour of confined amorphous indomethacin was evaluated in biorelevant intestinal media at pH 6.5. After 30 days of storage, 10.3 ± 1.2 % of the amorphous indomethacin cooled at 14 K/min and confined within microcontainers was found to be crystalline. When the melt of indomethacin was cooled at 23 or 36 K/min, 20.7 ± 1.5 and 31.0 ± 2.6 % of the indomethacin were found to be crystalline after storage for 30 days. Scanning electron microscopy showed a smooth surface of amorphous indomethacin within the microcontainers when cooling the melt at 14 K/min, whereas cracks and an uneven surface were observed when cooling at rates of 23 and 36 K/min. The uneven surface is hypothesised to be the main reason for the lower physical stability, as the cracks could act as nucleation sites for crystal growth. The rate of cooling was not seen to have any effect on the dissolution of amorphous indomethacin from the microcontainers. PMID:25786881

  18. Differential heating and cooling rates in bigeye tuna (Thunnus obesus Lowe): a model of non-steady state heat exchange.

    PubMed

    Malte, Hans; Larsen, Christina; Musyl, Michael; Brill, Richard

    2007-08-01

    We analyzed water temperature, visceral cavity temperature and depth data from archival tags retrieved from bigeye tuna (Thunnus obesus) at liberty in the central Pacific for up to 57 days using a mathematical model of heat exchange. Our model took into account the transfer of heat between the portions of the myotomes comprising red muscle fibers adjacent to the spinal column and served by vascular counter current heat exchanges (henceforth referred to as ;red muscle') and the water, as well as between the red muscle and the temperature sensor of the archival tags in the visceral cavity. Our model successfully predicted the recorded visceral cavity temperatures during vertical excursions provided that the rate constants for heat transfer between the ambient water and the red muscle during cooling (k(low)) and those during heating (k(high)) were very dissimilar. Least-squares fitting of k(low) and k(high) for the entire period that the fish were at liberty yielded values generally in the ranges 0.02-0.04 min(-1) and 0.2-0.6 min(-1) (respectively), with an average ratio k(high)/k(low) of approximately 12. Our results confirmed those from previous studies showing that bigeye tuna have extensive physiological thermoregulatory abilities probably exerted through changes of blood flow patterns that controlled the efficiency of vascular countercurrent heat exchanges. There was a small but significant negative correlation between k(low) and size, whereas there was no correlation between k(high) and size. The maximum swimming speeds during vertical excursions (calculated from the pressure data) occurred midway during ascents and averaged approximately 2 FL s(-1) (where FL=fork length), although speeds as high approximately 4-7 FL s(-1) were also noted. PMID:17644676

  19. Metallographic methods for revealing the multiphase microstructure of TRIP-assisted steels

    SciTech Connect

    Girault, E.; Van Humbeeck, J.; Aernoudt, E.; Jacques, P.; Delannay, F.; Harlet, P.; Mols, K.

    1998-02-01

    Classical etching techniques used for the investigation of steel microstructures allow the simultaneous observation of only a restricted number of phases. So far, this limitation has not been too detrimental, because most low-carbon steel grades possess a quite simple microstructure. The recent interest in the so-called TRIP-assisted multiphase steels characterized by complex microstructures requires new developments in metallographic methods. This paper proposes an extension of already known techniques to allow the study of four kinds of TRIP-aided steels. The actual restrictions justifying the development of an improved method are emphasized. In spite of its simplicity, the procedure has the advantage of allowing the simultaneous observation of the four phases that generally compose the microstructure of TRIP-assisted steels; that is, ferrite, bainite, austenite, and martensite. Light and electron microscopy as well as diffraction techniques are used to demonstrate the interest of the method.

  20. The metallographic revealing of twin formation in ZrNb industrial alloys

    NASA Astrophysics Data System (ADS)

    Chirkin, A. V.; Al-Nakow, Abubakir S.; Sherif, Salem M.

    1991-01-01

    The method of metallographic analysis in polarized light has been employed to reveal twins in Zr-Nb industrial alloys after plastic deformation. The twins appear during tensile testing of transverse sheet samples when σ y is exceeded. Most of the twins look like regular strips in the sheet plane, symmetric and stably oriented against the rolling and tensile directions. These twins are co-operative and cross grains with identical crystallographic orientation; the textured material behaves here as a pseudomonocrystal. The twin width is determined not only by the twin type, but also by the degree of deformation and increases with it. The twinning contribution in the practical deformation process is not important, if the general deformation degree is above 5-8%.

  1. Development of metallographic preparation techniques for group IVA and VA elements

    SciTech Connect

    Bingert, S. A.; Abeln, T. G.; Thoma, D. J.; Cooley, J. C.; Hults, W. L.; Kelly, A. M.

    2001-01-01

    Existing metallographic preparation techniques for Group IVA/VA (e.g. V, Ti, Ta, Hf, Nb, Zr) materials do not reveal all microstructural features inherent to the process history. As a result, new techniques have been developed and compared to existing procedures. For example, in pure tantalum, the new procedure exposes a substructure that is not evident using previously published techniques. In niobium, better grain boundary delineation is possible with the new process. Similar results are evident for titanium, zirconium, vanadium, and hafnium. The new preparation stage includes a chemical polish and etchant. The chemical polish was found to eliminate problems associated with the mechanical polish. Specifically, the chemical polish removes the worked surface and eliminates smearing. The etching stage serves to delineate the grain boundaries, and in some cases allows bright field as well as polarized or differential interference contrast (DIC) for optical examination. Finally, optical lighting conditions to enhance the observations available with the optimized procedure will be discussed.

  2. 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

  3. Effects of composition and cooling rate on the microstructure of Sn-3.7Ag-0.9Zn-Bi solders

    NASA Astrophysics Data System (ADS)

    Wang, X.; Liu, Y. C.; Wei, C.; Yu, L. M.; Gao, Z. M.; Dong, Z. Z.

    2009-09-01

    The effects of Bi addition, of less than 3 wt.%, and applied cooling rate on the solidified microstructure of the eutectic Sn-3.7Ag-0.9Zn (weight percent, hereafter) solder were investigated. As observed by microstructural analysis, the increase of Bi content favors the separation of the β-Sn and AgZn intermetallic compounds (IMCs) in the eutectic Sn-Ag-Zn solder. And there are some Bi precipitates formed along with the primary β-Sn dendrites as the concentration of Bi exceeds 2%. As the applied cooling rate increases, the microstructure of the Sn-3.7Ag-0.9Zn-Bi solder is refined, and the segregation of Bi is restrained. By increasing the amount of Bi, the microhardness of the solder increases.

  4. Cooling rate effects on the microstructure, solid content, and rheological properties of organogels of amides derived from stearic and (R)-12-hydroxystearic acid in vegetable oil.

    PubMed

    Toro-Vazquez, Jorge F; Morales-Rueda, Juan; Torres-Martínez, Adriana; Charó-Alonso, Miriam A; Mallia, V Ajay; Weiss, Richard G

    2013-06-25

    Using safflower oil as the liquid phase, we investigated the organogelation properties of stearic acid (SA), (R)-12-hydroxystearic acid (HSA), and different primary and secondary amides synthesized from SA and HSA. The objective was to establish the relationship between the gelator's molecular structure, solid content, and gels' microstructure that determines the rheological properties of organogels developed at two cooling rates, 1 and 20 °C/min. The results showed that the presence of a 12-OH group in the gelator molecule makes its crystallization kinetics cooling rate dependent and modifies its crystallization behavior. Thus, SA crystallizes as large platelets, while HSA crystallizes as fibers forming gels with higher solid content, particularly at 20 °C/min. The addition to HSA of a primary or a secondary amide bonded with an alkyl group resulted in gelator molecules that crystallized as fibrillar spherulites at both cooling rates. Independent of the cooling rate, gels of HSA and its amide derivatives showed thixotropic behavior. The rheological properties of the amide's organogels depend on a balance between hydrogen-bonding sites and the alkyl chain length bonded to the amide group. However, it might also be associated with the effect that the gelators' molecular weight has on crystal growth and its consequence on fiber interpenetration among vicinal spherulites. These results were compared with those obtained with candelilla wax (CW), a well-known edible gelling additive used by the food industry. CW organogels had higher elasticity than HSA gels but lower than the gels formed by amides. Additionally, CW gels showed similar or even higher thixotropic behavior than HSA and the amide's gels. These remarkable rheological properties resulted from the microstructural organization of CW organogels. We concluded that microstructure has a more important role determining the organogels' rheology than the solid content. The fitting models developed to describe the

  5. 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.

  6. 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.

  7. Structure formation in sugar containing pectin gels - influence of tartaric acid content (pH) and cooling rate on the gelation of high-methoxylated pectin.

    PubMed

    Kastner, H; Kern, K; Wilde, R; Berthold, A; Einhorn-Stoll, U; Drusch, S

    2014-02-01

    The aim of the study was the application of a recently published method, using structuring parameters calculated from dG'/dt, for the characterisation of the pectin sugar acid gelation process. The influence of cooling rate and pH on structure formation of HM pectin gels containing 65 wt.% sucrose were investigated. The results show that the structure formation process as well as the properties of the final gels strongly depended on both parameters. With increasing cooling rates from 0.5 to 1.0 K/min the initial structuring temperature slightly decreased and the maximum structuring velocity increased. The lower the cooling rates, the firmer and more elastic were the final gels. With increasing acid content (decreasing pH from 2.5-2.0) the initial structuring temperatures were nearly constant. The final gel properties varied visibly but not systematically. Gels with the lowest and highest pH were less elastic and weaker compared to those with medium acid concentrations. PMID:24099540

  8. Effect of Superheat, Cooling Rate, and Refractory Composition on the Formation of Non-metallic Inclusions in Non-oriented Electrical Steels

    NASA Astrophysics Data System (ADS)

    Luo, Yan; Conejo, Alberto Nava; Zhang, Lifeng; Chen, Lingfeng; Cheng, Lin

    2015-10-01

    The magnetic properties of electrical steels are improved with additions of silicon and aluminum; however, these elements also promote the formation of non-metallic inclusions. The presence of non-metallic inclusions in electrical steels severely affects its magnetic properties. In this work, the effect of cooling rate, superheat, and refractory composition on the formation of non-metallic inclusions has been investigated. The evolution in chemical composition has been reported using a new representation employing pseudo-quinary phase diagrams. It has been found that the concentration of MnO in the non-metallic inclusions plays a big role to control its population density. A critical value has been identified above which it is possible to achieve a large decrease in the total number of non-metallic inclusions in electrical steels, in addition to this, it was also possible to define the influence of cooling rate, superheat, and refractory chemical composition on the composition and population density of non-metallic inclusions. It was found that increasing cooling rate and a change of crucible from alumina-based to MgO-based, both increase the population density of NMI, on the contrary, superheat decreases the population density, depending on the concentration of MnO in the inclusions.

  9. Effect of Mn, Si, and Cooling Rate on the Formation of Iron-Rich Intermetallics in 206 Al-Cu Cast Alloys

    NASA Astrophysics Data System (ADS)

    Liu, K.; Cao, X.; Chen, X.-G.

    2012-10-01

    The solidification structures of commercial 206 Al-Cu cast alloys with 0.15 pct Fe have been studied using thermal analysis (TA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The EBSD results have shown that there are two iron-rich intermetallics: Chinese script α-Fe and platelet-like β-Fe. The addition of either Mn or Si has helped to promote the formation of α-Fe and hinder the precipitate of β-Fe. The combined addition of both Mn and Si is even more effective than the individual addition of either Mn or Si. The full solidification sequence of the 206 cast alloy has been established. The volume percent and formation temperature increase for α-Fe but decrease for β-Fe with increasing cooling rate. The platelet β-Fe can be effectively suppressed in 206 cast alloys by controlling the alloy chemistry and cooling rate. A casting process map is proposed to correlate the Mn and Si contents with cooling rates for the 206 cast alloys.

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:26386219

  14. 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.

  15. 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

  16. Porosity formation in AI-9 Wt Pct Si-3 Wt Pct Cu alloy systems: Metallographic observations

    NASA Astrophysics Data System (ADS)

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

    1996-02-01

    The formation of porosity in Al-9 wt Pct Si-3 wt Pct Cu-X alloys was studied as a function of (1) the hydrogen content of the melt; (2) the melt treatment additives, namely, modifier (Sr), grain refiner (TiB2), and primary silicon refiner (P); (3) alloying elements for precipitation hardening such as Mg and Zn; (4) intermetallics (α-iron, β-iron, sludge, and Al2Cu); and (5) solidification conditions (so-lidification time and solidus velocity). The results were statistically analyzed, based on the quanti-tative image analysis data of the porosity observed in samples obtained from a set of 72 solidification experiments. Metallographic aspects of pore size and pore morphology related to the preceding parameters and the possible mechanisms of porosity formation are highlighted in this article. The results show that a melt hydrogen content of 0.1 mL/100 g Al has the same effect on percentage porosity as that obtained with an addition of 185 ppm strontium to the melt. Grain refiner particles, phosphorus, and magnesium reduce percentage porosity, although in different magnitudes. A Mg-Sr or Mg-GR combination further reduces the percentage porosity observed in the casting. The β needles of the Al5FeSi intermetallic phase are very active as pore nucleation sites. All intermetallics, viz. β needles, α-Chinese script phase, Al2Cu phase, and sludge restrict pore growth and expansion. In-creasing the local solidification time or the solidus velocity increases the pore parameters. Pore growth in the two cases is attributed, respectively, to a diffusion-controlled growth process and to the formation of hot spots.

  17. Formation of perched lava ponds on basaltic volcanoes: Interaction between cooling rate and flow geometry allows estimation of lava effusion rates

    NASA Technical Reports Server (NTRS)

    Wilson, L.; Parfitt, E. A.

    1993-01-01

    Perched lava ponds are infrequent but distinctive topographic features formed during some basaltic eruptions. Two such ponds, each approximately 150 m in diameter, formed during the 1968 eruption at Napau Crater and the 1974 eruption of Mauna Ulu, both on Kilauea Volcano, Hawaii. Each one formed where a channelized, high volume flux lava flow encountered a sharp reduction of slope: the flow spread out radially and stalled, forming a well-defined terminal levee enclosing a nearly circular lava pond. We describe a model of how cooling limits the motion of lava spreading radially into a pond and compare this with the case of a channelized flow. The difference in geometry has a major effect, such that the size of a pond is a good indicator of the volume flux of the lava forming it. Lateral spreading on distal shallow slopes is a major factor limiting the lengths of lava flows.

  18. Effects of B and Cu Addition and Cooling Rate on Microstructure and Mechanical Properties in Low-Carbon, High-Strength Bainitic Steels

    NASA Astrophysics Data System (ADS)

    Sung, Hyo Kyung; Shin, Sang Yong; Hwang, Byoungchul; Lee, Chang Gil; Lee, Sunghak

    2012-10-01

    The effects of B and Cu addition and cooling rate on microstructure and mechanical properties of low-carbon, high-strength bainitic steels were investigated in this study. The steel specimens were composed mostly of bainitic ferrite, together with small amounts of acicular ferrite, granular bainite, and martensite. The yield and tensile strengths of all the specimens were higher than 1000 MPa and 1150 MPa, respectively, whereas the upper shelf energy was higher than 160 J and energy transition temperature was lower than 208 K (-65 °C) in most specimens. The slow-cooled specimens tended to have the lower strengths, higher elongation, and lower energy transition temperature than the fast-cooled specimens. The Charpy notch toughness was improved with increasing volume fraction of acicular ferrite because acicular ferrites favorably worked for Charpy notch toughness even when other low-toughness microstructures such as bainitic ferrite and martensite were mixed together. To develop high-strength bainitic steels with an excellent combination of strength and toughness, the formation of bainitic microstructures mixed with acicular ferrite was needed, and the formation of granular bainite was prevented.

  19. 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.

  20. 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.

  1. The stratosphere - Climatologies of the radiative heating and cooling rates and the diabatically diagnosed net circulation fields

    NASA Technical Reports Server (NTRS)

    Callis, Linwood B.; Boughner, Robert E.; Lambeth, James D.

    1987-01-01

    Stratospheric solar, IR, and net radiative heating are calculated on a monthly basis using solar and IR radiative codes and satellite derived distributions of ozone, water vapor, and temperature. Divergence-free, zonally averaged, advective fields are diagnosed using the calculated diabatic heating; associated stream functions are derived. The stratospheric transport of inert tracers is studied. Analysis of the diagnosed advective fields reveal that: (1) entry into the mid- to upper stratosphere of tropospheric air is mainly from altitude regions of + or - 10 deg at the equatorial tropopause; (2) at latitudes poleward of + or - 15 deg, tracers transported from the troposphere into the stratosphere are transported toward the pole and then downward and out of the stratosphere; and (3) the presence of net cooling cells in the lower stratospheric polar regions is important. The interannual variability of the diabatic circulation is estimated using heating and advection fields derived from LIMS data.

  2. 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

  3. 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.

  4. A technical bias: differences in cooling rates prevent ampoules from being a reliable index of stem cell cryopreservation in large volumes.

    PubMed

    Douay, L; Lopez, M; Gorin, N C

    1986-08-01

    Ampoule tests are commonly used as an index of the cryopreservation efficiency of marrow stem cells in bags. We have studied the recovery of hematopoietic progenitor cells (CFU-GM, BFUe) in 52 ampoules and compared it to the recovery in 83 standard bags. Our data showed significantly deficient CFU-GM and BFUe recoveries (respectively 47 +/- 31% and 31 +/- 30%) in ampoules when compared to bags (respectively 72 +/- 22% and 64 +/- 19%; P less than 0.001). Moreover, a good progenitor cell recovery (greater than or equal to 50%) was observed in only 46% of frozen ampoules versus 100% observed in frozen bags (P less than 0.05). We were able to relate this nonoptimal recovery to an excessively rapid freezing rate of -9 degrees C/min following the release of fusion heat which occurred in ampoules, while the freezing rate was constantly maintained at -2 degrees C/min in the corresponding bags. We therefore conclude that the cooling conditions have to be carefully controlled to ensure that the bags and ampoules are both cooled under the same conditions. Otherwise, ampoules would not be a reliable index of the true progenitor cells' cryopreservation efficiency in bags. PMID:3527561

  5. 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.

  6. Experimental Investigation of the Effect of Cooling Rate on Melilite/Liquid Distribution Coefficients for Sr, Ba, and TI in Type B Refractory Inclusion Melts

    NASA Astrophysics Data System (ADS)

    Simon, S. B.; Davis, A. M.; Richter, F. M.; Grossman, L.

    1996-03-01

    It is well established that Type B1 refractory inclusions were once at least partially molten. These inclusions are thought to represent closed magmatic systems, but attempts to model the trace element contents in melilite in these CAIs have not met with much success. Observed abundances of most trace elements tend to be significantly higher than those predicted using equilibrium melilite/liquid distribution coefficients. Boundary layers have been proposed as an explanation, but in the case of Sr, its D of ~0.8 is too high to give rise to boundary layers sufficiently enriched in Sr to account for the observed enrichments. We have investigated the possibility that Ds increase with increasing cooling rate. We found that Ds for Ti, Sr and Ba are virtually invariant with akermanite and with cooling rate, and the models still do not fit the observations, especially for Ba, which is off by a factor of ~20. The results indicate that a process occurred during the crystallization of melilite that we have yet to understand. _

  7. 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.

  8. 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

  9. Radiative power and electron cooling rates for oxygen in steady-state and transient plasmas at densities beyond the coronal limit

    SciTech Connect

    Keane, C.; Skinner, C.H.

    1986-01-01

    We have developed a time-dependent, collisional-radiative model to calculate radiative power and electron cooling rates for oxygen at intermediate densities (10/sup 16/ cm/sup -3/ less than or equal to n/sub e/ less than or equal to 10/sup 20/ cm/sup -3/) where the usual coronal approximation is not valid. Large differences from coronal values are predicted. The behavior of the steady-state radiative power loss coefficient, L/sub Z, is investigated as the electron density is increased. Generalized power loss coefficients applicable to transient plasmas are derived and applied to ionizing and recombining oxygen plasmas. Time-dependent effects are found to play a large role both in terms of the total radiated power and the net electron energy loss rate. 41 refs., 11 figs.

  10. The relationship between oxygen consumption rate and viability of in vivo-derived pig embryos vitrified by the micro volume air cooling method.

    PubMed

    Sakagami, N; Nishida, K; Misumi, K; Hirayama, Y; Yamashita, S; Hoshi, H; Misawa, H; Akiyama, K; Suzuki, C; Yoshioka, K

    2016-01-01

    The aim of this study was to assess the viability of vitrified-warmed in vivo-derived pig embryos after measuring the oxygen consumption rate. Six days after artificial insemination, blastocysts were collected from gilts and vitrified by the micro volume air cooling method. The oxygen consumption rate was measured in 60 vitrified-warmed embryos, which were then cultured for 48h to assess the viability. The survival (re-expansion) rate of embryos after warming was 85.0%. The average oxygen consumption rate of embryos immediately after warming was greater in embryos which could re-expand during subsequent culture (F=0.75±0.04) than that in those which failed to re-expand (F=0.33±0.05). Moreover, the oxygen consumption rate of vitrified-warmed embryos was greater in the hatched (F=0.88±0.06) than that in the not-hatched group (F=0.53±0.04). When the oxygen consumption rate of the vitrified-warmed embryos and the numbers of viable and dead cells in embryos were determined, there was a positive correlation between the oxygen consumption rate and the number of live cells (P<0.01, r=0.538). A total of 29 vitrified embryos after warming and measuring the oxygen consumption rate were surgically transferred into uterine horns of two recipients. Both of the recipients become pregnant and farrowed 12 healthy piglets. These results demonstrate that the oxygen consumption rate of vitrified-warmed pig embryos can be related to the number of live cells and that the measurement of oxygen consumption of embryos after cryopreservation may be useful for estimating embryo survivability. PMID:26642748

  11. 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.

  12. 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.

  13. Design and demonstration of heat pipe cooling for NASP and evaluation of heating methods at high heating rates

    SciTech Connect

    Merrigan, M.A.; Sena, J.T.

    1989-01-01

    An evaluation of two heating methods for demonstration of NASP leading edge heat pipe technology was conducted. The heating methods were and rf induction heated plasma jet and direct rf induction. Tests were conducted to determine coupling from the argon plasma jet on a surface physically similar to a heat pipe. A molybdenum tipped calorimeter was fabricated and installed in an rf induction heated plasma jet for the test. The calorimetric measurements indicated a maximum power coupling of approximately 500 W/cm{sup 2} with the rf plasma jet. The effect of change in gas composition on the heating rate was investigated using helium. An alternative to the plasma heating of a heat pipe tip, an rf concentrator was evaluated for coupling to the hemispherical tip of a heat pipe. A refractory metal heat pipe was designed, fabricated, and tested for the evaluation. The heat pipe was designed for operation at 1400 to 1900 K with power input to 1000 W/cm{sup 2} over a hemispherical nose tip. Power input of 800 W/cm{sup 2} was demonstrated using the rf concentrator. 2 refs., 13 figs.

  14. Btu flow rate meter proof of concept demonstration for district heating and cooling systems: Final technical report

    SciTech Connect

    Mawardi, O.K.

    1988-10-01

    This report describes a research effort devoted to the development and subsequent feasibility demonstration of an instrument for the remote sensing of the Btu flow rate in a steam or hot water heating system. The concept of the Btu meter is based on a differential hot wire anemometer invented by Osman K. Mawardi. The incentive in the development of this device is the increased demand for an inexpensive and accurate (better than 1%) Btu meter. The ability of the meter to be read remotely is essential, since it is an effective way of reducing the manpower costs of the company operating the heating system. Other features of the Btu meter which are included in the design are simplicity of construction, ruggedness, and flexibility of the electronic interfacing system. The latter feature permits the incorporation of the telemetering circuit in a telephone or radio-based communication system. Both of these alternatives are commercially available today and are quite economical. With small modifications of the interfacing circuitry, the meter can be linked to a fiber optics automated meter reading network. 15 refs., 20 figs., 1 tab.

  15. NASA Microclimate Cooling Challenges

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.

    2004-01-01

    The purpose of this outline form presentation is to present NASA's challenges in microclimate cooling as related to the spacesuit. An overview of spacesuit flight-rated personal cooling systems is presented, which includes a brief history of cooling systems from Gemini through Space Station missions. The roles of the liquid cooling garment, thermal environment extremes, the sublimator, multi-layer insulation, and helmet visor UV and solar coatings are reviewed. A second section is presented on advanced personal cooling systems studies, which include heat acquisition studies on cooling garments, heat rejection studies on water boiler & radiators, thermal storage studies, and insulation studies. Past and present research and development and challenges are summarized for the advanced studies.

  16. 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.

  17. 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.

  18. Rheological behavior of Al-Mg-Si-Cu alloys in the mushy state obtained by partial remelting and partial solidification at high cooling rate

    NASA Astrophysics Data System (ADS)

    Fabrègue, D.; Deschamps, A.; Suéry, M.; Poole, W. J.

    2006-05-01

    This work investigates the mechanical behavior of two aluminum alloys in the mushy state, the alloy AA6056 and an alloy based on mixing AA6056 and AA4047. These alloys have been studied to give insight into the susceptibility to hot tearing, which occurs during laser welding of AA6056 with 4047 filler wire. Two types of isothermal tensile tests have been conducted: (1) tests during partial remelting and (2) tests after partial solidification at a high cooling rate. Results show that the maximum tensile stress increases with increasing solid volume fraction. Both materials exhibit visco-plastic behavior for solid fractions in the range 0.9 to 0.99, except for a critical solid fraction of 0.97, where the semisolid material also shows minimum ductility. The stress levels observed for the remelting experiments are larger than those found for partial solidification experiments at the same solid fraction due to the influence of the microstructure. The influence of temperature and strain rate on the maximum stress is described by using a constitutive law that takes into account the fraction of grain boundaries wetted by the liquid.

  19. New routine for calculating non-LTE infrared cooling/heating rates in the Earth mesosphere and lower thermosphere for applications in GCMs

    NASA Astrophysics Data System (ADS)

    Kutepov, A.; Feofilov, A.; Medvedev, A. S.

    2012-12-01

    We developed a new fast and accurate routine for calculating the non-LTE radiative cooling/heating (C/H) rates in CO2 bands in the Earth mesosphere/lower thermosphere. This routine: a) utilizes exact accelerated lambda iteration (ALI) solution of the multilevel vibrational problem in CO2; b) applies the opacity distribution function (ODF) technique for fast and accurate treatment of the radiative transfer in the CO2 bands; c) accounts for the heating due to absorption of the near infrared solar radiation; c) allows varying input collisional rate coefficients and the O3P density; d) accounts for additional C/H caused by temperature and O3P/CO2 density fluctuations associated with small-scale gravity waves, which are not resolved in current GCMs, e) calculates C/H with a prescribed accuracy. New routine is about 10000 times faster than the line by line (LBL) approach when reproducing C/H above 65 km with accuracy of ± 0.3 K/day. We compare it with the existing non-LTE C/H parametrizations, and provide recommendations for its implementation in GCMs.

  20. 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.

  1. Spectroscopic, energetic and metallographic investigations of the laser lap welding of AISI 304 using the response surface methodology

    NASA Astrophysics Data System (ADS)

    Rizzi, Domenico; Sibillano, Teresa; Pietro Calabrese, Paolo; Ancona, Antonio; Mario Lugarà, Pietro

    2011-07-01

    Spectroscopic signals originated by the laser-induced plasma optical emission have been simultaneously investigated together with energetic and metallographic analyses of CO 2 laser welded stainless steel lap joint, using the Response Surface Methodology. This statistical approach allowed us to study the influence of the laser beam power and the laser welding speed on the following response parameters: plasma plume electron temperature, joint penetration depth and melted area. A clear correlation has been found between all the investigated response parameters. The results have been shown to be consistent with quantitative considerations on the energy supplied to the workpiece as far as the laser power and travel speed were varied. The regression model obtained in this way could be a valuable starting point to develop a closed loop control of the weld penetration depth and the melted area in the investigated process window.

  2. 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.

  3. Stacking with stochastic cooling

    NASA Astrophysics Data System (ADS)

    Caspers, Fritz; Möhl, Dieter

    2004-10-01

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105 the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some considerations to the 'azimuthal' schemes.

  4. 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.

  5. Cooling of dense stars

    NASA Technical Reports Server (NTRS)

    Tsuruta, S.

    1972-01-01

    Cooling rates were calculated for neutron stars of about one solar mass and 10 km radius, with magnetic fields from zero to about 10 to the 14th power gauss, for extreme cases of maximum and zero superfluidity. The results show that most pulsars are so cold that thermal ionization of surface atoms would be negligible. Nucleon superfluidity and crystallization of heavy nuclei were treated quantitatively, and more realistic hadron star models were chosen. Cooling rates were calculated for a stable hyperon star near the maximum mass limit, a medium weight neutron star, and a light neutron star with neutron-rich heavy nuclei near the minimum mass limit. Results show that cooling rates are a sensitive function of density. The Crab and Vela pulsars are considered, as well as cooling of a massive white dwarf star.

  6. 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.

  7. Surface forcing of the infrared cooling profile over the Tibetan Plateau. I - Influence of relative longwave radiative heating at high altitude. II - Cooling-rate variation over large-scale plateau domain during summer monsoon transition

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Shi, Lei

    1992-01-01

    The role of the Tibetan Plateau on the behavior of the surface longwave radiation budget is investigated, and the behavior of the vertical profile of longwave cooling over the plateau, including its diurnal variation, is quantified. A medium spectral-resolution IR radiative transfer model utilizing a simple modification for applications in idealized complex (valley) terrain is developed for the investigation. An understanding of how surface and elevation biophysical factors, which are highly variable over the large-scale plateau domain, regulate the spatial distribution of clear-sky IR cooling during the transition phase of the summer monsoon, is described.

  8. Igneous Cooling Rate constraints on the Accretion of the lower Oceanic Crust in Mid-ocean Ridges: Insights from a new Thermo-mechanical Model

    NASA Astrophysics Data System (ADS)

    Garrido, C. J.; Machetel, P.

    2005-12-01

    We report the results of a new thermo-mechanical model of crustal flow beneath fast spreading mid-ocean ridges to investigate both the effect of deep, near off-axis hydrothermal convection on the thermal structure of the magma chamber and the role of variable number of melt intrusions on the accretion of the oceanic crust. In our model the melt is injected at the center of the axial magma chamber with a 'needle' with adjustable porosity at different depths allowing the simulation of different arrangements of melt injection and supply within the magma chamber. Conversely to previous models, the shape of the magma chamber -defined as the isotherm where 95% solidification of the melt occurs- is not imposed but computed from the steady state reached by the thermal field considering the heat diffusion and advection and the latent heat of crystallization. The motion equation is solved for a temperature and phase dependent viscosity. The thermal diffusivity is also dependent on temperature and depth, with a higher diffusivity in the upper plutonic crust to account for more efficient hydrothermal cooling at these crustal levels. In agreement with previous non-dynamic thermal models, our results show that near, deep off-axis hydrothermal circulation strongly affects the shape of the axial magma by tightening isotherms in the upper half of the plutonic oceanic crust where hydrothermal cooling is more efficient. Different accretion modes have however little effect on the shape of the magma chamber, but result in variable arrangements of flow lines ranging from tent-shape in a single-lens accretion scenario to sub-horizontal in "sheeted-sill" intrusion models. For different intrusion models, we computed the average Igneous Cooling Rates (ICR) of gabbros by dividing the crystallization temperature interval of gabbros by the integrated time, from the initial intrusion to the point where it crossed the 950 °C isotherm where total solidification of gabbro occurs, along individual

  9. 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.

  10. Personal Cooling System

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Cool Head, a personal cooling system for use in heat stress occupations, is a spinoff of a channeled cooling garment for space wear. It is portable and includes a heat exchanger, control display unit, liquid reservoir and temperature control unit. The user can eliminate 40 to 60 percent of his body's heat storage and lower heart rate by 50 to 80 beats a minute. The system is used by the Army, Navy, crop dusting pilots, heavy equipment operators and auto racing drivers and is marketed by Life Enhancement Technologies, LLC. Further applications are under consideration.

  11. Influence of cooling rate on the ability of frozen-thawed sperm to bind to heterologous zona pellucida, as assessed by competitive in vitro binding assays in the ocelot (Leopardus pardalis) and tigrina (Leopardus tigrinus).

    PubMed

    Baudi, D L K; Jewgenow, K; Pukazhenthi, B S; Spercoski, K M; Santos, A S; Reghelin, A L S; Candido, M V; Javorouski, M L; Müller, G; Morais, R N

    2008-01-15

    We evaluated the influence of two cooling rates (from 25 to 5 degrees C) on post-thaw function of frozen sperm in ocelots (Leopardus pardalis; n=3 males) and tigrinas (Leopardus tigrinus; n=4 males). Seven normospermic (>70% normal sperm) electroejaculates from each species were diluted with a 4% glycerol freezing medium, divided into two aliquots, and assigned to one of two cooling rates: fast or slow (0.7 or 0.16 degrees C/min, respectively). Sperm motility index (SMI) and percentage of sperm with an intact acrosome were assessed before freezing and after thawing, and the ability of sperm to bind to the zona pellucida of IVM domestic cat oocytes were assessed in a competitive in vitro sperm-binding assay. Regardless of the cooling rate, frozen-thawed sperm from both species exhibited a SMI of 50; approximately 20 and approximately 32% of post-thaw sperm had an intact acrosome in ocelots and tigrinas, respectively (P<0.05). The mean (+/-S.E.M.) number of sperm bound per oocyte was higher for fast-cooled (8.5+/-1.3) than slow-cooled (2.5+/-0.3; P<0.01) ocelot sperm. In contrast, more tigrina sperm bound to domestic cat oocytes when cooled slowly versus quickly (5.8+/-0.9 versus 2.7+/-0.4, P<0.05). In conclusion, cryopreservation decreased sperm function in both species, and the oocyte-binding assay was the most efficient method to detect functional differences in post-thaw sperm. PMID:17977588

  12. 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.

  13. 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…

  14. 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.

  15. 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.

  16. Temperature History and Metallographic Structure of 0.45%C Steel Processed by Frictional Stir Burnishing

    NASA Astrophysics Data System (ADS)

    Kiuchi, Satoshi; Sasahara, Hiroyuki

    Significant enhancement of hardness characteristics was achieved through the Frictional Stir Burnishing (FSB) process. The enhanced region was generated by the FSB process where the thickness and hardness were approximately 200 µm and 900 HV, respectively, under the conditions of spindle speed of 10000 min-1, a feed rate of 200 mm/min and a processing load of 750 N. The processing temperature was approximately 600˜750 °C under compressive stress condition. Although this temperature is lower than A3 transform point (normally 780 °C), it is known that A3 transform point decreases under the compressive stress condition. And after the tool passed, the temperature dropped rapidly. This process can be assumed to be the same as a quenching process. However, the obtained hardness value is harder than that of the regular quenched material. When the processing load was 500 N, extremely hard regions over 1000 HV were obtained. In this case, it is thought that the material was not transformed into martensite. It can be concluded that the severe stirring process of FSB caused the grain refinement.

  17. 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)

  18. 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)

  19. An Improved Optical Model for the Non-LTE Problem for the CO2 Molecule in the Atmosphere of Mars: Nighttime Populations of Vibrational States and the Rate of Radiative Cooling of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Ogibalov, V. P.; Shved, G. M.

    2003-01-01

    The estimates of the population of excited vibrational states of the CO2 molecule and of the rate of radiative cooling of the atmosphere in the 15-μm CO2 band are given for the nighttime mesosphere and thermosphere of Mars. For the first time, these estimates are made (1) with allowance for the overlap of lines in the 15-μm band; (2) for a wide set of vibrational states of seven isotopes of the CO2 molecule, which was used earlier in the solution of a similar terrestrial problem; and (3) using the rate constant for quenching of the CO2(0110) state in collisions with oxygen atoms, which has been recently measured for low temperatures by Khvorostovskaya et al. (2002). The main results are as follows. 1. The approximation of isolated lines provides a satisfactory accuracy of determining the radiative cooling rate and overestimates vibrational temperatures of the states of the ν2 mode by no more than 3 K for the 12C16O2 molecule and by no more than 2 K for low-abundant isotopes of the CO2 molecule. 2. A reasonably high accuracy of estimating the cooling rate can be achieved by taking into account only fundamental vibrational transitions in 12C16O2, 13C16O2, 16O12C18O, and 16O12C17O molecules and the hot transitions 2ν2 --> ν2 and 3ν2 --> 2ν2 in the 12C16O2 molecule. 3. The vertical profile of the total rate of radiative cooling displays two peaks. The maximum near a height of 130 km is very sensitive to temperature and to the ratio of the mixture for oxygen in the atmosphere.

  20. 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

    Seki, Shinsuke; Jin, Bo; Mazur, Peter

    2014-02-01

    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., ≫1000°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 83%, 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

  1. Measurement of rate constant for quenching CO2(0110) by atomic oxygen at low temperatures: reassessment of the population of CO2(0110) and the CO2 15-μm emission cooling in the lower thermosphere

    NASA Astrophysics Data System (ADS)

    Shved, Gustav M.; Khvorostovskaya, Lyudmila E.; Potekhin, Igor Y.; Ogibalov, Vladimir P.; Uzyukova, Tatyana V.

    2003-04-01

    The paper presents the first laboratory measurement of the rate constant for quenching the CO2(0110) state during collisions of CO2 molecules with O atoms at temperatures realized near the Earth's mesopause. The measurement was carried out with a hollow-cathode glow discharge in the temperature range 206-358 K. The measured values are significantly smaller than those commonly used in solving the non-LTE CO2 problem for the vibrational states of the mode ν2 in the atmospheres of the Earth, Venus, and Mars. The measured temperature dependence of the rate constant is approximated by a simple relation, which is recommended for solving the above problem. The value of this rate constant is absolutely critical to remotely sense temperature, and hence also constituent densities, in the upper mesosphere and lower thermosphere of the Earth. The use of the new values of the rate constant significantly decreased the rate of cooling by the CO2 15-μm emission in the terrestrial lower thermosphere as compared to the previous estimates obtained for this rate. Over the most area of the Earth's surface, the maximum cooling rate occurs at an altitude of about 110 km and amounts to about 20 K/day.

  2. Generation of 287 W, 5.5 ps pulses at 78 MHz repetition rate from a cryogenically cooled Yb:YAG amplifier seeded by a fiber chirped-pulse amplification system.

    PubMed

    Hong, Kyung-Han; Siddiqui, Aleem; Moses, Jeffrey; Gopinath, Juliet; Hybl, John; Ilday, F Omer; Fan, Tso Yee; Kärtner, Franz X

    2008-11-01

    We generate linearly polarized, 287 W average-power, 5.5 ps pulses using a cryogenically cooled Yb:YAG amplifier at a repetition rate of 78 MHz. An optical-to-optical efficiency of 41% is obtained at 700 W pump power. A 6 W, 0.4 nm bandwidth picosecond seed source at 1029 nm wavelength is constructed using a chirped-pulse fiber amplification chain based on chirped volume Bragg gratings. The combination of a fiber amplifier system and a cryogenically cooled Yb:YAG amplifier results in good spatial beam quality at large average power. Low nonlinear phase accumulation as small as 5.1 x 10(-3) rad in the bulk Yb:YAG amplifier supports power scalability to a > 10 kW level without being affected by self-phase modulation. This amplification system is well suited for pumping high-power high-repetition-rate optical parametric chirped-pulse amplifiers. PMID:18978891

  3. 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.

  4. 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.

  5. Stochastic cooling

    SciTech Connect

    Bisognano, J.; Leemann, C.

    1982-03-01

    Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron.

  6. 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.

  7. Methods of beam cooling

    SciTech Connect

    Sessler, A.M.

    1996-02-01

    Diverse methods which are available for particle beam cooling are reviewed. They consist of some highly developed techniques such as radiation damping, electron cooling, stochastic cooling and the more recently developed, laser cooling. Methods which have been theoretically developed, but not yet achieved experimentally, are also reviewed. They consist of ionization cooling, laser cooling in three dimensions and stimulated radiation cooling.

  8. 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.

  9. Stochastic Cooling with Schottky Band Overlap

    SciTech Connect

    Lebedev, Valeri

    2006-03-20

    Optimal use of stochastic cooling is essential to maximize the antiproton stacking rate for Tevatron Run II. Good understanding and characterization of the cooling is important for the optimization. The paper is devoted to derivation of the Fokker-Plank equations justified in the case of near or full Schottky base overlap for both longitudinal and transverse coolings.

  10. 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 ...

  11. 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.

  12. Effect of the cooling rate on dimerization of C60(•-) in fullerene salt (DMI+)2·(C60(•-))·{Cd(Et2NCS2)2I-}.

    PubMed

    Konarev, Dmitri V; Khasanov, Salavat S; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N

    2012-03-19

    The salt (DMI(+))(2)·(C(60)(•-))·{Cd(Et(2)NCS(2))(2)I(-)} (1) containing fullerene radical anions, the anions of cadmium diethyldithiocarbamate iodide, and N,N'-dimethylimidazolium cations was obtained. Fullerenes are monomeric in 1 at 250 K and form three-dimensional packing in which each fullerene has nearly tetrahedral surroundings from neighboring fullerenes. Fullerenes with a shorter interfullerene center-to-center distance of 10.031(2) Å form spiral chains arranged along the lattice c axis. The convolution consists of four fullerene molecules. Dimerization realized in 1 within the spiral chains below 135 K manifests a strong dependence on the cooling rate. The "frozen" monomeric phase was obtained upon instant quenching of 1. This phase is stable below 95 K for a long time but slowly converted to the dimeric phase at T > 95 K. It exhibits a weak antiferromagnetic interaction of spins below 95 K (the Weiss temperature is -4 K), which results in the splitting of the electron paramagnetic resonance (EPR) signal into two components below 10 K. A disordered phase containing both C(60)(•-) monomers and singly bonded (C(60)(-))(2) dimers with approximately 0.5/0.5 occupancies is formed at an intermediate cooling rate (for 20 min). The position of each fullerene in this phase is split into three positions slightly shifted relative to each other. The central position corresponds to nonbonded fullerenes with interfullerene center-to-center distances of 9.94-10.00 Å. Two other positions are coincided to dimeric fullerenes formed with the right and left fullerene neighbors within the spiral chain. This intermediate phase is paramagnetic with nearly zero Weiss temperature due to isolation of C(60)(•-) by diamagnetic species and exhibits a strongly asymmetric EPR signal below 20 K. A diamagnetic phase containing ordered singly bonded (C(60)(-))(2) dimers can be obtained only upon slow cooling of the crystal for 6 h. PMID:22376157

  13. Evaporative cooling in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Maltezos, George; Rajagopal, Aditya; Scherer, Axel

    2006-08-01

    Evaporative cooling is an effective and energy efficient way to rapidly remove heat from a system. Specifically, evaporative cooling in microfluidic channels can provide a cost-effective solution for the cooling of electronic devices and chemical reactors. Here we present microfluidic devices fabricated by using soft-lithography techniques to form simple fluidic junctions between channels carrying refrigerant and channels carrying N2 gas. The effects of channel geometry and delivery pressure on the performance of refrigeration through vaporization of acetone, isopropyl alcohol, and ethyl ether were characterized. By varying gas inlet pressures, refrigerants, and angles of the microfluidic junctions, optimal cooling conditions were found. Refrigeration rates in excess of 40°C/s were measured, and long lasting subzero cooling in the junction could be observed.

  14. Turbine airfoil film cooling

    NASA Astrophysics Data System (ADS)

    Hylton, Larry D.

    1986-10-01

    Emphasis is placed on developing more accurate analytical models for predicting turbine airfoil external heat transfer rates. Performance goals of new engines require highly refined, accurate design tools to meet durability requirements. In order to obtain improvements in analytical capabilities, programs are required which focus on enhancing analytical techniques through verification of new models by comparison with relevant experimental data. The objectives of the current program are to develop an analytical approach, based on boundary layer theory, for predicting the effects of airfoil film cooling on downstream heat transfer rates and to verify the resulting analytical method by comparison of predictions with hot cascade data obtained under this program.

  15. 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

  16. On cooling tea and coffee

    NASA Astrophysics Data System (ADS)

    Rees, W. G.; Viney, C.

    1988-05-01

    Factors influencing the rate of cooling of hot coffee and tea have been investigated theoretically and studied experimentally using deliberately ``domestic'' apparatus. It is demonstrated that black coffee cools faster than white coffee under the same conditions. Under most (but not all) circumstances, if coffee is required to be as hot as possible several minutes after its preparation, any milk or cream should be added immediately, rather than just before drinking.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Rates of particle size reduction and passage are faster for legume compared with cool-season grass, resulting in lower rumen fill and less effective fiber.

    PubMed

    Kammes, K L; Allen, M S

    2012-06-01

    Effects of forage family on rates of particle size reduction in, and passage from, the rumen and the relationship of these effects with preliminary dry matter intake (pDMI) were evaluated using 13 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 18-d treatment periods. During the preliminary period, pDMI of individual cows ranged from 19.6 to 29.5 kg/d (mean = 25.9 kg/d). Experimental treatments were diets containing either a) alfalfa silage (AL) or b) orchardgrass silage (OG) as the sole forage. Silages were chopped to 10-mm theoretical length of cut and contained 42.3 and 58.2% neutral detergent fiber (NDF) for alfalfa and orchardgrass, respectively. Both diets contained approximately 25% forage NDF and 30% total NDF. Feed, orts, rumen, and duodenal samples were wet sieved to fractionate particles above (large) and below (small) 2.36 mm. Indigestible NDF (iNDF) was used as a flow marker. Preliminary DMI, an index of nutrient demand, was determined during the last 4 d of the preliminary period when cows were fed a common diet and used as a covariate. Main effects of forage family and their interaction with pDMI were tested by ANOVA. Approximately 75% of the NDF consumed was large and 25% was small for both treatments, but cows fed AL consumed more iNDF and less potentially digestible NDF (pdNDF) than cows fed OG. The AL diet increased the reduction rate (large to small) compared with OG despite less rumination per unit of forage NDF for AL than OG, suggesting alfalfa NDF was more fragile than orchardgrass NDF. Over 55% of particles in the rumen were below 2.36 mm for AL and OG, indicating that particle size was not a limiting constraint to passage. Passage rates (k(p)) of large iNDF and large pdNDF were similar for AL and OG, but AL increased k(p) of large pdNDF and OG decreased it as pDMI increased. The AL diet increased k(p) of small iNDF and small pdNDF compared with OG, resulting in lower rumen fill

  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. 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

  5. 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.

  6. 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.

  7. 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.

  8. Electron kinetics in a cooling plasma

    SciTech Connect

    Helander, P.; Smith, H.; Fueloep, T.; Eriksson, L.-G.

    2004-12-01

    The distribution function of suprathermal electrons in a slowly cooling plasma is calculated by an asymptotic expansion in the cooling rate divided by the collision frequency. Since the collision frequency decreases with increasing velocity, a high-energy tail forms in the electron distribution function as the bulk population cools down. Under certain simplifying assumptions (slow cooling, constant density, Born approximation of cross sections), the distribution function evolves to a self-similar state where the tail is inversely proportional to the cube of the velocity. Its practical consequences are discussed briefly.

  9. Adiabatic cooling of antiprotons.

    PubMed

    Gabrielse, G; Kolthammer, W S; McConnell, R; Richerme, P; Kalra, R; Novitski, E; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Fitzakerley, D; George, M C; Hessels, E A; Storry, C H; Weel, M; Müllers, A; Walz, J

    2011-02-18

    Adiabatic cooling is shown to be a simple and effective method to cool many charged particles in a trap to very low temperatures. Up to 3×10(6) p are cooled to 3.5 K-10(3) times more cold p and a 3 times lower p temperature than previously reported. A second cooling method cools p plasmas via the synchrotron radiation of embedded e(-) (with many fewer e(-) than p in preparation for adiabatic cooling. No p are lost during either process-a significant advantage for rare particles. PMID:21405511

  10. Adiabatic Cooling of Antiprotons

    SciTech Connect

    Gabrielse, G.; Kolthammer, W. S.; McConnell, R.; Richerme, P.; Kalra, R.; Novitski, E.; Oelert, W.; Grzonka, D.; Sefzick, T.; Zielinski, M.; Fitzakerley, D.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; Muellers, A.; Walz, J.

    2011-02-18

    Adiabatic cooling is shown to be a simple and effective method to cool many charged particles in a trap to very low temperatures. Up to 3x10{sup 6} p are cooled to 3.5 K--10{sup 3} times more cold p and a 3 times lower p temperature than previously reported. A second cooling method cools p plasmas via the synchrotron radiation of embedded e{sup -} (with many fewer e{sup -} than p) in preparation for adiabatic cooling. No p are lost during either process--a significant advantage for rare particles.

  11. Sustainable cooling method for machining titanium alloy

    NASA Astrophysics Data System (ADS)

    Boswell, B.; Islam, M. N.

    2016-02-01

    Hard to machine materials such as Titanium Alloy TI-6AI-4V Grade 5 are notoriously known to generate high temperatures and adverse reactions between the workpiece and the tool tip materials. These conditions all contribute to an increase in the wear mechanisms, reducing tool life. Titanium Alloy, for example always requires coolant to be used during machining. However, traditional flood cooling needs to be replaced due to environmental issues, and an alternative cooling method found that has minimum impact on the environment. For true sustainable cooling of the tool it is necessary to account for all energy used in the cooling process, including the energy involved in producing the coolant. Previous research has established that efficient cooling of the tool interface improves the tool life and cutting action. The objective of this research is to determine the most appropriate sustainable cooling method that can also reduce the rate of wear at the tool interface.

  12. 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.

  13. Temperature controller for a fluid cooled garment

    NASA Technical Reports Server (NTRS)

    Chambers, A. B.; Blackaby, J. R.; Billingham, J. (Inventor)

    1973-01-01

    An automatic controller for controlling the inlet temperature of the coolant to a fluid cooled garment without requiring skin sensors is described. Temperature is controlled by the wearer's evaporative water loss rate.

  14. 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.

  15. The three stages of magma ocean cooling

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    1992-01-01

    Models of magma ocean (MO) cooling and crystallization can provide important constraints on MO plausibility for a given planet, on the origin of long term, stable crusts, and even on the origin of the solar system. Assuming the MO is initially extensive enough to have a mostly molten surface, its first stage of cooling is an era of radiative heat loss from the surface, with extremely rapid convection below, and no conductive layer in between. The development of the chill crust starts the second stage of MO cooling. Heat loss is now limited by conduction through the crust. The third stage of cooling starts when the near surface MO evolves compositionally to the point of saturation with feldspar. At this point, the cooling rate again precipitously diminishes, the rate of crustal thickness growth as a function of temperature suddenly increases. More work on incorporating chemical constraints into the evolving physical models of MO solidification would be worthwhile.

  16. 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.

  17. 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.

  18. Debuncher cooling performance

    SciTech Connect

    Derwent, P.F.; McGinnis, David; Pasquinelli, Ralph; Vander Meulen, David; Werkema, Steven; /Fermilab

    2005-11-01

    We present measurements of the Fermilab Debuncher momentum and transverse cooling systems. These systems use liquid helium cooled waveguide pickups and slotted waveguide kickers covering the frequency range 4-8 GHz.

  19. Debuncher Cooling Performance

    SciTech Connect

    Derwent, P. F.; McGinnis, David; Pasquinelli, Ralph; Vander Meulen, David; Werkema, Steven

    2006-03-20

    We present measurements of the Fermilab Debuncher momentum and transverse cooling systems. These systems use liquid helium cooled waveguide pickups and slotted waveguide kickers covering the frequency range 4-8 GHz.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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 apparatus for water-cooled engines

    SciTech Connect

    Fujikawa, T.; Tamba, S.

    1986-05-20

    A cooling apparatus is described for a water-cooled internal combustion engine including a shaft that rotates when the engine is running, the apparatus comprising a centrifugal fan adapted to be connected to and rotated by the shaft, the fan having an intake air port and a discharge air opening, a rotary screen adapted to be operatively connected to and rotated by the shaft, the screen being disposed in the intake air port, a cooling radiator, a spiral-shaped duct connecting the radiator with the discharge air opening, and separating means on the duct, the separating means comprising an opening formed in the outer wall of the duct.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. 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

  14. 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.

  15. Cooling, AGN Feedback and Star Formation in Cool-Core Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg; Ruszkowski, Mateusz

    2015-01-01

    The feedback from active galactic nuclei (AGNs) is widely considered to be the major heating source in cool-core galaxy clusters to prevent a classical cooling flow. Numerical simulations with AGN feedback have successfully suppressed radiative cooling, but generally fail to reproduce the right amount of cold gas and the expected cyclical AGN activities. We perform adaptive mesh simulations including both momentum-driven AGN feedback and star formation to study the interplay between cooling, AGN heating and star formation over ~ 6.5 Gyr time in an isolated cool-core cluster. Cold clumps first cool out of the ICM due to the non-liner perturbation driven by the AGN jets. These cold clumps feed both star formation and the supermassive black hole (SMBH), triggering an AGN outburst which increases the entropy of the ICM and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, which leads to a brief shutoff of the AGN. The ICM quickly cools and develops multiphase gas again, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. The average star formation rate is ~40 solar mass/yr. The black hole accretion rate shows a large scatter, but the average correlates well with the star formation rate and is roughly one order of magnitude lower.

  16. 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.

  17. Stochastic cooling in RHIC

    SciTech Connect

    Brennan J. M.; Blaskiewicz, M.; Mernick, K.

    2012-05-20

    The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.

  18. Personal cooling in hot workings

    SciTech Connect

    Tuck, M.A.

    1999-07-01

    The number of mines experiencing climatic difficulties worldwide is increasing. In a large number of cases these climatic difficulties are confined to working areas only or to specific locations within working areas. Thus the problem in these mines can be described as highly localized, due to a large extent not to high rock temperatures but due to machine heat loads and low airflow rates. Under such situations conventional means of controlling the climate can be inapplicable and/or uneconomic. One possible means of achieving the required level of climatic control, to ensure worker health and safety whilst achieving economic gains, is to adopt a system of active man cooling. This is the reverse of normal control techniques where the cooling power of the ventilating air is enhanced in some way. Current methods of active man cooling include ice jackets and various umbilical cord type systems. These have numerous drawbacks, such as limited useful exposure times and limitations to worker mobility. The paper suggests an alternative method of active man cooling than those currently available and reviews the design criteria for such a garment. The range of application of such a garment is discussed, under both normal and emergency situations.

  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. Semioptimal practicable algorithmic cooling

    SciTech Connect

    Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2011-04-15

    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.

  1. 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.

  2. Hydrogen film cooling investigation

    NASA Technical Reports Server (NTRS)

    Rousar, D. C.; Ewen, R. L.

    1973-01-01

    Effects of flow turning, flow acceleration, and supersonic flow on film cooling were determined experimentally and correlated in terms of an entrainment film cooling model. Experiments were conducted using thin walled metal test sections, hot nitrogen mainstream gas, and ambient hydrogen or nitrogen as film coolants. The entrainment film cooling model relates film cooling effectiveness to the amount of mainstream gases entrained with the film coolant in a mixing layer. The experimental apparatus and the analytical model used are described in detail and correlations for the entrainment fraction and film coolant-to-wall heat transfer coefficient are presented.

  3. Power electronics cooling apparatus

    DOEpatents

    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.

  4. 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.

  5. X-Ray spectroscopy of cooling flows

    NASA Technical Reports Server (NTRS)

    Prestwich, Andrea

    1996-01-01

    Cooling flows in clusters of galaxies occur when the cooling time of the gas is shorter than the age of the cluster; material cools and falls to the center of the cluster potential. Evidence for short X-ray cooling times comes from imaging studies of clusters and X-ray spectroscopy of a few bright clusters. Because the mass accretion rate can be high (a few 100 solar mass units/year) the mass of material accumulated over the lifetime of a cluster can be as high as 10(exp 12) solar mass units. However, there is little evidence for this material at other wavelengths, and the final fate of the accretion material is unknown. X-ray spectra obtained with the Einstein SSS show evidence for absorption; if confirmed this result would imply that the accretion material is in the form of cool dense clouds. However ice on the SSS make these data difficult to interpret. We obtained ASCA spectra of the cooling flow cluster Abell 85. Our primary goals were to search for multi-temperature components that may be indicative of cool gas; search for temperature gradients across the cluster; and look for excess absorption in the cooling region.

  6. 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

  7. 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.

  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. Cooling and recombination processes in cometary plasma

    NASA Technical Reports Server (NTRS)

    Wallis, M. K.; Ong, R. S. B.

    1976-01-01

    The ion electron plasma in comets is examined for cooling processes which result from its interactions with the neutral coma. A cometary coma model is formulated that is composed predominantly of H2O and its decomposition products where electrons are cooled in a variety of processes at rates varying with energy. It is shown that solar plasma plus accumulated cometary ions and electrons is affected very strongly as it flows into the coma. The electrons are rapidly cooled and all but some 10% of the ions undergo charge exchange. Photodissociation of H2O is assumed where ion electron recombination is the dominant loss process.

  10. 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. PMID:20867439

  11. Fermilab recycler stochastic cooling commissioning and performance

    SciTech Connect

    D. Broemmelsiek; Ralph Pasquinelli

    2003-06-04

    The Fermilab Recycler is a fixed 8 GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. The Recycler has two roles in Run II. First, to store antiprotons from the Fermilab Antiproton Accumulator so that the antiproton production rate is no longer compromised by large numbers of antiprotons stored in the Accumulator. Second, to receive antiprotons from the Fermilab Tevatron at the end of luminosity periods. To perform each of these roles, stochastic cooling in the Recycler is needed to preserve and cool antiprotons in preparation for transfer to the Tevatron. The commissioning and performance of the Recycler stochastic cooling systems will be reviewed.

  12. Liquid spray cooling of a heated surface

    NASA Technical Reports Server (NTRS)

    Grissom, W. M.; Wierum, F. A.

    1981-01-01

    The lowest surface temperature possible for the existance of spray evaporative cooling is determined experimentally to be a linear function of the impinging spray mass flux. A conduction-controlled analytical model of droplet evaporation gives fairly good agreement with experimental measurements at atmospheric pressure. At reduced pressures droplet evaporation rates are decreased significantly such that an optimum operating pressure exists for each desired surface heat flux. The initiation of the 'Leidenfrost state' provides the upper surface temperature bound for spray evaporative cooling.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Cooling histories of Apollo 15 quartz-normative basalts

    NASA Technical Reports Server (NTRS)

    Grove, T. L.; Walker, D.

    1977-01-01

    Controlled cooling rate studies of vitrophyre 15597 are used to calculate the physical properties of a quartz-normative magma as well as cooling histories of Apollo 15 quartz-normative basalts (QNB). Pyroxene phenocrysts of a QNB magma do not settle appreciably during the cooling of the flow unit; this behavior is consistent with the small degree of chemical differentiation that occurred between members of the suite. Two types of cooling histories for QNB are discerned. The vitrophyres experienced initial slow cooling followed by rapid cooling, and the coarse-grained microgabbros underwent slow nearly linear cooling histories. Textural evidence suggests that lunar vitrophyres crystallized near the top of the flow. It is suggested that the pattern of cooling may have been caused by the chilling of liquids that inherited early crystals in the interior of the flow.

  18. 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

  19. 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.

  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. 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.

  2. Why Cool Roofs?

    ScienceCinema

    Chu, Steven

    2013-05-29

    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.

  3. Cool Earth Solar

    ScienceCinema

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

    2014-02-26

    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.

  4. 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.

  5. Coherent electron cooling

    SciTech Connect

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  6. 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.

  7. Liquid Cooled Garments

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Astronauts working on the surface of the moon had to wear liquid-cooled garments under their space suits as protection from lunar temperatures which sometimes reach 250 degrees Fahrenheit. In community service projects conducted by NASA's Ames Research Center, the technology developed for astronaut needs has been adapted to portable cooling systems which will permit two youngsters to lead more normal lives.

  8. 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.

  9. 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…

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Turbine blade cooling

    SciTech Connect

    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.

  15. 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.

  16. 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

  17. 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

  18. Radiative and gas cooling of falling molten drops

    NASA Technical Reports Server (NTRS)

    Robinson, M. B.

    1978-01-01

    The supercooling rate and solidification time for molten drops of niobium, copper, and lead are calculated. Calculations for both radiation and helium gas cooling are presented in order to estimate the influence that the presence of helium gas would have upon the cooling rate of falling drops in the Marshall Space Flight Center space processing drop tube.

  19. Turbine airfoil with an internal cooling system having vortex forming turbulators

    DOEpatents

    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.

  20. Collision assisted Zeeman cooling with multiple types of atoms

    NASA Astrophysics Data System (ADS)

    Hamilton, Mathew S.; Wilson, Rebekah F.; Roberts, Jacob L.

    2014-01-01

    Through a combination of spin-exchange collisions in a magnetic field and optical pumping, it is possible to cool a gas of atoms without requiring the loss of atoms from the gas. This technique, collision assisted Zeeman cooling (CAZ), was developed theoretically assuming a single atomic species [G. Ferrari, Eur. Phys. J. D 13, 67 (2001)]. We have extended this cooling technique to a system of two atomic species rather than just one and have developed a simple analytic model describing the cooling rate. We find that the two-isotope CAZ cooling scheme has a clear theoretical advantage in systems that are reabsorption limited.

  1. 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.

  2. 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}⊙ {{yr}}-1, with an average of ˜ 40 {M}⊙ {{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.

  3. An experimental investigation of a gas turbine disk cooling system

    NASA Astrophysics Data System (ADS)

    Kobayashi, N.; Matsumato, M.; Shizuya, M.

    1983-03-01

    The results of an experimental study of the cooling of a model disk similar to an engine disk are compared with the results obtained by three-dimensional finite difference computation, and it is reconfirmed that the determination of cooling air temperature is one of the most important data for predicting the disk temperature. The minimum cooling air flow rate necessary to prevent ingress of external hot gas is determined by the fluctuation of cooling air temperature inside the wheel space with the external axial hot gas flow for values of the rotational Reynolds number of 0-6.5 million. The effect of rotational speed on the minimum cooling air flow rate is found to be negligible, and it is shown that the determination of the ingress of hot gas using the pressure difference criterion underestimates the minimum cooling air flow rate.

  4. 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.

  5. MEIC electron cooling program

    DOE PAGESBeta

    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

  6. Evaporative cooling of the dipolar hydroxyl radical.

    PubMed

    Stuhl, Benjamin K; Hummon, Matthew T; Yeo, Mark; Quéméner, Goulven; Bohn, John L; Ye, Jun

    2012-12-20

    Atomic physics was revolutionized by the development of forced evaporative cooling, which led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases and ultracold optical lattice simulations of condensed-matter phenomena. More recently, substantial progress has been made in the production of cold molecular gases. Their permanent electric dipole moment is expected to generate systems with varied and controllable phases, dynamics and chemistry. However, although advances have been made in both direct cooling and cold-association techniques, evaporative cooling has not been achieved so far. This is due to unfavourable ratios of elastic to inelastic scattering and impractically slow thermalization rates in the available trapped species. Here we report the observation of microwave-forced evaporative cooling of neutral hydroxyl (OH(•)) molecules loaded from a Stark-decelerated beam into an extremely high-gradient magnetic quadrupole trap. We demonstrate cooling by at least one order of magnitude in temperature, and a corresponding increase in phase-space density by three orders of magnitude, limited only by the low-temperature sensitivity of our spectroscopic thermometry technique. With evaporative cooling and a sufficiently large initial population, much colder temperatures are possible; even a quantum-degenerate gas of this dipolar radical (or anything else it can sympathetically cool) may be within reach. PMID:23257881

  7. Optimization of evaporative cooling

    NASA Astrophysics Data System (ADS)

    Sackett, C. A.; Bradley, C. C.; Hulet, R. G.

    1997-05-01

    Recent experiments have used forced evaporative cooling to produce Bose-Einstein condensation in dilute gases. The evaporative cooling process can be optimized to provide the maximum phase-space density with a specified number of atoms remaining. We show that this global optimization is approximately achieved by locally optimizing the cooling efficiency at each instant. We discuss how this method can be implemented, and present the results for our 7Li trap. The predicted behavior of the gas is found to agree well with experiment.

  8. Feedback cooling of currents

    NASA Astrophysics Data System (ADS)

    Washburn, Sean

    1989-02-01

    Just as feedback can be used to correct errors in the output voltages of amplifiers, it can also be used to remove noise from the current through a resistor. Such a feedback amplifier behaves as a refrigerator cooling the electrons in a resistor connnected to it. This principle has been recognized since the 1940s but has been largely ignored because the cooling power available from such refrigerators is miniscule. It is pointed out here that the method might be practical for cooling the currents in the microscopic circuits that are typical of modern electrical engineering and recent studies in transport physics.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  16. 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

  17. An objective method for screening and selecting personal cooling systems based on cooling properties.

    PubMed

    Elson, John; Eckels, Steve

    2015-05-01

    A method is proposed for evaluation and selection of a personal cooling system (PCS) incorporating PCS, subject, and equipment weights; PCS run time; user task time; PCS cooling power; and average metabolic rate. The cooling effectiveness method presented is derived from first principles and allows those who select PCSs for specific applications to compare systems based on their projected use. This can lower testing costs by screening for the most applicable system. Methods to predict cooling power of PCSs are presented and are compared to data taken through standard manikin testing. The cooling effectiveness ranking is presented and validated against human subject test data. The proposed method provides significant insight into the application of PCS on humans. However, the interaction a humans with a PCS is complex, especially considering the range of clothing ensembles, physiological issues, and end use scenarios, and requires additional analysis. PMID:25683529

  18. Modeling growth of Clostridium perfringens in pea soup during cooling.

    PubMed

    de Jong, Aarieke E I; Beumer, Rijkel R; Zwietering, Marcel H

    2005-02-01

    Clostridium perfringens is a pathogen that mainly causes food poisoning outbreaks when large quantities of food are prepared. Therefore, a model was developed to predict the effect of different cooling procedures on the growth of this pathogen during cooling of food: Dutch pea soup. First, a growth rate model based on interpretable parameters was used to predict growth during linear cooling of pea soup. Second, a temperature model for cooling pea soup was constructed by fitting the model to experimental data published earlier. This cooling model was used to estimate the effect of various cooling environments on average cooling times, taking into account the effect of stirring and product volume. The growth model systematically overestimated growth of C. perfringens during cooling in air, but this effect was limited to less than 0.5 log N/ml and this was considered to be acceptable for practical purposes. It was demonstrated that the growth model for C. perfringens combined with the cooling model for pea soup could be used to sufficiently predict growth of C. perfringens in different volume sizes of pea soup during cooling in air as well as the effect of stirring, different cooling temperatures, and various cooling environments on the growth of C. perfringens in pea soup. Although fine-tuning may be needed to eliminate inaccuracies, it was concluded that the combined model could be a useful tool for designing good manufacturing practices (GMP) procedures. PMID:15787757

  19. 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.

  20. 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.

  1. Sisyphus cooling of lithium

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul; Kim, Geena; Joshi, Trinity; Mukherjee, Biswaroop; Tiarks, Daniel; Müller, Holger

    2014-02-01

    Laser cooling to sub-Doppler temperatures by optical molasses is thought to be inhibited in atoms with unresolved, near-degenerate hyperfine structure in the excited state. We demonstrate that such cooling is possible in one to three dimensions, not only near the standard D2 line for laser cooling, but over a wide range extending to the D1 line. Via a combination of Sisyphus cooling followed by adiabatic expansion, we reach temperatures as low as 40 μK, which corresponds to atomic velocities a factor of 2.6 above the limit imposed by a single-photon recoil. Our method requires modest laser power at a frequency within reach of standard frequency-locking methods. It is largely insensitive to laser power, polarization and detuning, magnetic fields, and initial hyperfine populations. Our results suggest that optical molasses should be possible with all alkali-metal species.

  2. 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 ...

  3. Too cool to work

    NASA Astrophysics Data System (ADS)

    Moya, Xavier; Defay, Emmanuel; Heine, Volker; Mathur, Neil D.

    2015-03-01

    Magnetocaloric and electrocaloric effects are driven by doing work, but this work has barely been explored, even though these caloric effects are being exploited in a growing number of prototype cooling devices.

  4. 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)

  5. Waveguide cooling system

    NASA Technical Reports Server (NTRS)

    Chen, B. C. J.; Hartop, R. W. (Inventor)

    1981-01-01

    An improved system is described for cooling high power waveguides by the use of cooling ducts extending along the waveguide, which minimizes hot spots at the flanges where waveguide sections are connected together. The cooling duct extends along substantially the full length of the waveguide section, and each flange at the end of the section has a through hole with an inner end connected to the duct and an opposite end that can be aligned with a flange hole in another waveguide section. Earth flange is formed with a drainage groove in its face, between the through hole and the waveguide conduit to prevent leakage of cooling fluid into the waveguide. The ducts have narrowed sections immediately adjacent to the flanges to provide room for the installation of fasteners closely around the waveguide channel.

  6. Comparative study of patches for liquid cooled garments.

    NASA Technical Reports Server (NTRS)

    Shitzer, A.; Chambers, A. B.

    1973-01-01

    Tests were performed on 12 cooling patches of various designs to establish criteria for the evaluation of their performance in liquid-cooled suits in industrial, military and aerospace applications. The thermal effectiveness value was 0.088 for patch designs with a double spiral flow pattern, and 0.075 for patch designs with a parallel flow pattern. The ratio of thermal energy transfer rate to cooling-medium pumping power requirement is indicated as the prime performance characteristic to be considered in the selection and rating of cooling patches.

  7. 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.

  8. 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)

  9. Liquid cooled helmet

    NASA Technical Reports Server (NTRS)

    Elkins, William (Inventor); Williams, Bill A. (Inventor)

    1979-01-01

    Liquid cooled helmet comprising a cap of flexible material adapted to fit the head of a person, cooling panels mounted inside the cap forming passageways for carrying a liquid coolant, the panels being positioned to engage the cranium and neck of a person wearing the helmet, inlet and outlet lines communicating with the passageways, and releasable straps for securing the helmet about the neck of the wearer.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Effects of regolith/megaregolith insulation on the cooling histories of differentiated asteroids

    NASA Technical Reports Server (NTRS)

    Haack, Henning; Rasmussen, Kaare L.; Warren, Paul H.

    1990-01-01

    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.

  15. 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.

  16. 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.

  17. Behavior of Forged S-816 Turbine Blades in Steady-state Operation of J33-9 Turbojet Engine with Stress-rupture and Metallographic Evaluations / by F. B.garrett, C. A. Gyorgak, and J. W. Weeton

    NASA Technical Reports Server (NTRS)

    Garrett, Floyd B; Gyorgak, Charles A; Weeton, John Waldemar

    1953-01-01

    An investigation was conducted to determine the behavior of recently produced, forged S-816 turbine blades in a full-scale turbojet engine, and in particular, the scatter in performance of the alloy. The turbine blades were operated as continuously as possible at a temperature of 1500 degrees F and a centrifugal stress of 21,500 pounds per square inch. The operating lives of the turbine blades varied from 181 to 539 hours, a range of 358 hours. Stress-rupture properties of specimens cut from blade airfoils also varied considerably, as much as 1257 hours at 20,000 pounds per square inch and 1500 degrees F. Since the variability of scatter of stress-rupture data is greater than that of blade performance, the scatter is probably caused by variations in the properties of the forged blades rather than by variations caused by engine operation or installation of the blades. Metallographic examinations were made to determine possible causes of the scatter and although numerous differences in microstructures of blades were found, no consistent tendencies were observed and the findings did not permit an explanation of the scatter of blade performance. The results of the metallographic examinations and of the physical tests indirectly indicated variables in the fabricating method caused the scatter in properties.

  18. 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.

  19. Experimental study on the evaporative cooling of an air-cooled condenser with humidifying air

    NASA Astrophysics Data System (ADS)

    Wen, Mao-Yu; Ho, Ching-Yen; Jang, Kuang-Jang; Yeh, Cheng-Hsiung

    2014-02-01

    Using six different materials to construct a water curtain, this study aims to determine the most effective spray cooling of an air cooled heat exchanger under wet conditions. The experiments were carried out at a mass flow rate of 0.005-0.01 kg/s (spraying water), an airspeed of 0.6-2.4 m/s and a run time of 0-72 h for the material degradation tests. The experimental results indicate that the cooling efficiency, the heat rejection, and the sprinkling density increase as the amount of spraying water increases, but, the air-flow of the condenser is reduced at the same time. In addition, the cooling efficiency of the pads decreases with an increase of the inlet air velocity. In terms of experimental range, the natural wood pulp fiberscan can reach 42.7-66 % for cooling efficiency and 17.17-24.48 % for increases of heat rejection. This means that the natural wood pulp fiberscan pad most effectively enhances cooling performance, followed in terms of cooling effectiveness by the special non-woven rayon pad, the woollen blanket, biochemistry cotton and kapok, non-woven cloth of rayon cotton and kapok, and white cotton pad, respectively. However, the natural wood pulp fiberscan and special non-woven rayon display a relatively greater degradation of the cooling efficiency than the other test pads used in the material degradation tests.

  20. Cryopreservation of kunming mouse oocytes using slow cooling, ultrarapid cooling and vitrification protocols.

    PubMed

    Men, H S; Chen, J C; Ji, W Z; Shang, E Y; Yang, S C; Zou, R J

    1997-05-01

    The cryopreservation of oocytes has been only marginally successful with any of the current protocols, including slow cooling, rapid cooling and vitrification. We wished to test the hypothesis that oocytes from a single mouse strain would freeze successfully by 1 of the 3 mentioned protocols. Unfertilized Kunming mouse oocytes obtained 14 h after PMSG/hCG administration were randomly assigned to be cryopreserved after slow cooling, ultra rapid cooling and vitrification. Oocytes were thawed by straws being placed into 37 degrees C water, and their morphological appearance and in vitro fertilization capability were compared with that of oocytes that had not undergone cryopreservation. Survival of oocytes was indicated by the absence of darkened ooplasm or by broken membranes or zona pellucida. Functional integrity was evaluated by the formation of a 2-cell embryo after IVF. Survival rate of slow cooled oocytes did not differ from that seen in vitrified oocytes (55.1 vs 65.9%) but was significantly lower in the rapidly cooled oocytes (24.2%; P < 0.01). The results of IVF of slow cooled and vitrified oocytes were similar to those of the control group (72 and 73 vs 77%; P > 0.05). It appears that Kunming mouse oocytes can be successfully cryopreserved using the slow cooling method with 1,2-propanediol and vitrification, which contains both permeating and nonpermeating cryoprotectants. PMID:16728088

  1. 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…

  2. Cool Flame Quenching

    NASA Technical Reports Server (NTRS)

    Pearlman, Howard; Chapek, Richard

    2001-01-01

    Cool flame quenching distances are generally presumed to be larger than those associated with hot flames, because the quenching distance scales with the inverse of the flame propagation speed, and cool flame propagation speeds are often times slower than those associated with hot flames. To date, this presumption has never been put to a rigorous test, because unstirred, non-isothermal cool flame studies on Earth are complicated by natural convection. Moreover, the critical Peclet number (Pe) for quenching of cool flames has never been established and may not be the same as that associated with wall quenching due to conduction heat loss in hot flames, Pe approx. = 40-60. The objectives of this ground-based study are to: (1) better understand the role of conduction heat loss and species diffusion on cool flame quenching (i.e., Lewis number effects), (2) determine cool flame quenching distances (i.e, critical Peclet number, Pe) for different experimental parameters and vessel surface pretreatments, and (3) understand the mechanisms that govern the quenching distances in premixtures that support cool flames as well as hot flames induced by spark-ignition. Objective (3) poses a unique fire safety hazard if conditions exist where cool flame quenching distances are smaller than those associated with hot flames. For example, a significant, yet unexplored risk, can occur if a multi-stage ignition (a cool flame that transitions to a hot flame) occurs in a vessel size that is smaller than that associated with the hot quenching distance. To accomplish the above objectives, a variety of hydrocarbon-air mixtures will be tested in a static reactor at elevated temperature in the laboratory (1g). In addition, reactions with chemical induction times that are sufficiently short will be tested aboard NASA's KC-135 microgravity (mu-g) aircraft. The mu-g results will be compared to a numerical model that includes species diffusion, heat conduction, and a skeletal kinetic mechanism

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Cooling flows in clusters of galaxies

    SciTech Connect

    Meiksin, A.A.

    1988-01-01

    X-ray measurements of many clusters of galaxies reveal a hot Intracluster Medium (ICM) that has a cooling time less than a Hubble time. The consequent decrease in the central pressure support of the ICM will result in an inward cooling flow. The inferred accretion rates are typically several hundred solar masses per year. The cD or giant elliptical found at the center of every cooling flow would be substantially altered by the accreted gas, and may even have been created by the flow. Optical, UV, and radio measurements, however, fail to find adequate evidence for massive amounts of cool gas. The lore is that the gas is transformed into stars of such low mass that they do not give very peculiar colors to the central galaxy. In this thesis, after a review of past and current literature, two tasks are undertaken. The first is to examine the role heat conduction could play. It is demonstrated that the density and temperature profiles of the cooling flows in Virgo and Perseus are consistent with a steady-state model in which that conduction reduces the accretion rates by an order of magnitude. The second task is to simulate the evolution of a cooling flow, and possible formation of a galaxy from thermal instabilities, in a proper cosmological setting. Two evolutionary stages are found, a dynamical accretion state composed of two competing similarity solutions followed by a quasi-steady-state cooling flow. The onset of the second stage is very recent. During either stage, so few stars may be created that their colors, even adopting a standard initial mass function, would be consistent with the existing optical and UV constraints.

  17. Nozzleless Spray Cooling Using Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Ang, Kar Man; Yeo, Leslie; Friend, James; Hung, Yew Mun; Tan, Ming Kwang

    2015-11-01

    Due to its reliability and portability, surface acoustic wave (SAW) atomization is an attractive approach for the generation of monodispersed microdroplets in microfluidics devices. Here, we present a nozzleless spray cooling technique via SAW atomization with key advantage of downward scalability by simply increasing the excitation frequency. With generation of micron size droplets through surface destabilization using SAW, the clogging issues commonly encountered by spraying nozzle can be neutralized. Using deionised water, cooling is improved when the atomization rate is increased and the position of the device is optimized such that the atomized droplets can be easily seeded into the upstream of the flow circulation. Cooling is further improved with the use of nanofluids; a suspension of nanoparticles in water. By increasing nanoparticle mass concentration from 1% to 3%, cooling is enhanced due to the deposition and formation of nanoparticle clusters on heated surface and eventually increase the surface area. However, further increase the concentration to 10% reduces the cooling efficiency due to drastic increase in viscosity μ that leads to lower atomization rate which scales as ṁ ~μ - 1 / 2 .

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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. PMID:25770525

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Cooling Panel Optimization for the Active Cooling System of a Hypersonic Aircraft

    NASA Technical Reports Server (NTRS)

    Youn, B.; Mills, A. F.

    1995-01-01

    Optimization of cooling panels for an active cooling system of a hypersonic aircraft is explored. The flow passages are of rectangular cross section with one wall heated. An analytical fin-type model for incompressible flow in smooth-wall rectangular ducts with coupled wall conduction is proposed. Based on this model, the a flow rate of coolant to each design minimum mass flow rate or coolant for a single cooling panel is obtained by satisfying hydrodynamic, thermal, and Mach number constraints. Also, the sensitivity of the optimal mass flow rate of coolant to each design variable is investigated. In addition, numerical solutions for constant property flow in rectangular ducts, with one side rib-roughened and coupled wall conduction, are obtained using a k-epsilon and wall function turbulence model, these results are compared with predictions of the analytical model.

  13. 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.

  14. 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/.

  15. 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.

  16. Deep mine cooling system

    SciTech Connect

    Conan, J.

    1984-11-06

    A deep mine cooling system comprising a compressor supplied with air and rotatively driven by a motor and an expansion turbine supplied with compressed air from said compressor and driving an actuating unit, wherein the compressed air, after leaving the compressor but prior to reaching the expansion turbine, passes through a steam generator whose output provides the energy required to operate an absorption refrigeration machine used to cool utility water for mining, said compressed air on leaving the steam generator going to a first heat exchanger in which it yields calories to a water circuit comprising a second heat exchanger, said second heat exchanger giving off the calories absorbed by the water in the first heat exchanger to the air fed by the second heat exchanger to a drying cell that is regenerated by said air from the second heat exchanger, said drying cell being part of a set of two cells working in alternation, the other cell in the set receiving the compressed air from the first heat exchanger, such that the compressed air is fed to said expansion turbine after leaving said drying unit, and wherein the air exhausted from said expansion turbine is sent to a third heat exchanger after which it is distributed according to the needs of the mine, said third exchanger being traversed by the water collected in the mine, cooled in said exchanger and circulated upon leaving said exchanger to meet the cool water requirements of the mine.

  17. Elementary stochastic cooling

    SciTech Connect

    Tollestrup, A.V.; Dugan, G

    1983-12-01

    Major headings in this review include: proton sources; antiproton production; antiproton sources and Liouville, the role of the Debuncher; transverse stochastic cooling, time domain; the accumulator; frequency domain; pickups and kickers; Fokker-Planck equation; calculation of constants in the Fokker-Planck equation; and beam feedback. (GHT)

  18. 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,…

  19. COOLING TOWER PLUME MODEL

    EPA Science Inventory

    A review of recently reported cooling tower plume models yields none that is universally accepted. The entrainment and drag mechanisms and the effect of moisture on the plume trajectory are phenomena which are treated differently by various investigators. In order to better under...

  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.