WorldWideScience

Sample records for surface cooling rate

  1. High cloud variations with surface temperature from 2002 to 2015: Contributions to atmospheric radiative cooling rate and precipitation changes

    Science.gov (United States)

    Liu, Run; Liou, Kuo-Nan; Su, Hui; Gu, Yu; Zhao, Bin; Jiang, Jonathan H.; Liu, Shaw Chen

    2017-05-01

    The global mean precipitation is largely constrained by atmospheric radiative cooling rates (Qr), which are sensitive to changes in high cloud fraction. We investigate variations of high cloud fraction with surface temperature (Ts) from July 2002 to June 2015 and compute their radiative effects on Qr using the Fu-Liou-Gu plane-parallel radiation model. We find that the tropical mean (30°S-30°N) high cloud fraction decreases with increasing Ts at a rate of about -1.0 ± 0.34% K-1 from 2002 to 2015, which leads to an enhanced atmospheric cooling around 0.86 W m-2 K-1. On the other hand, the northern midlatitudes (30°N-60°N) high cloud fraction increases with surface warming at a rate of 1.85 ± 0.65% K-1 and the near-global mean (60°S-60°N) high cloud fraction shows a statistically insignificant decreasing trend with increasing Ts over the analysis period. Dividing high clouds into cirrus, cirrostratus, and deep convective clouds, we find that cirrus cloud fraction increases with surface warming at a rate of 0.32 ± 0.11% K-1 (0.01 ± 0.17% K-1) for the near-global mean (tropical mean), while cirrostratus and deep convective clouds decrease with surface warming at a rate of -0.02 ± 0.18% K-1 and -0.33 ± 0.18% K-1 for the near-global mean and -0.64 ± 0.23% K-1 and -0.37 ± 0.13% K-1 for the tropical mean, respectively. High cloud fraction response to feedback to Ts accounts for approximately 1.9 ± 0.7% and 16.0 ± 6.1% of the increase in precipitation per unit surface warming over the period of 2002-2015 for the near-global mean and the tropical mean, respectively.

  2. Cooling rate calculations for silicate glasses.

    Science.gov (United States)

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

    1986-03-01

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

  3. Effect of Salted Ice Bags on Surface and Intramuscular Tissue Cooling and Rewarming Rates.

    Science.gov (United States)

    Hunter, Eric J; Ostrowski, Jennifer; Donahue, Matthew; Crowley, Caitlyn; Herzog, Valerie

    2016-02-01

    Many researchers have investigated the effectiveness of different cryotherapy agents at decreasing intramuscular tissue temperatures. However, no one has looked at the effectiveness of adding salt to an ice bag. To compare the cooling effectiveness of different ice bags (wetted, salted cubed, and salted crushed) on cutaneous and intramuscular temperatures. Repeated-measures counterbalanced design. University research laboratory. 24 healthy participants (13 men, 11 women; age 22.46 ± 2.33 y, height 173.25 ± 9.78 cm, mass 74.51 ± 17.32 kg, subcutaneous thickness 0.63 ± 0.27 cm) with no lower-leg injuries, vascular diseases, sensitivity to cold, compromised circulation, or chronic use of NSAIDs. Ice bags made of wetted ice (2000 mL ice and 300 mL water), salted cubed ice (intervention A; 2000 mL of cubed ice and 1/2 tablespoon of salt), and salted crushed ice (intervention B; 2000 mL of crushed ice and 1/2 tablespoon of salt) were applied to the posterior gastrocnemius for 30 min. Each participant received all conditions with at least 4 d between treatments. Cutaneous and intramuscular (2 cm plus adipose thickness) temperatures of nondominant gastrocnemius were measured during a 10-min baseline period, a 30-min treatment period, and a 45-min rewarming period. Differences from baseline were observed for all treatments. The wetted-ice and salted-cubed-ice bags produced significantly lower intramuscular temperatures than the salted-crushed-ice bag. Wetted-ice bags produced the greatest temperature change for cutaneous tissues. Wetted- and salted-cubed-ice bags were equally effective at decreasing intramuscular temperature at 2 cm subadipose. Clinical practicality may favor salted-ice bags over wetted-ice bags.

  4. Mechanisms available for cooling plants’ surfaces

    Directory of Open Access Journals (Sweden)

    Prokhorov Alexey Anatolievich

    2016-12-01

    Full Text Available The essay briefly touches upon the main mechanisms to cool down the plats’ surfaces that lead to condensation of atmospheric moisture; methods for experimental verification of these mechanisms are presented therein.

  5. Dry cooling systems with plastic surfaces

    International Nuclear Information System (INIS)

    Roma, Carlo; Leonelli, Vincenzo

    1975-01-01

    Research and experiments made on dry cooling systems with plastic surfaces are described. The demonstration program planned in Italy for a 100Gcal/h dry cooling system is exposed, and an installation intended for a large 1300Mwe nuclear power station is described with reference to the assembly (exploitation and maintenance included). The performance and economic data relating to this installation are also exposed [fr

  6. Cryopreservation: Vitrification and Controlled Rate Cooling.

    Science.gov (United States)

    Hunt, Charles J

    2017-01-01

    Cryopreservation is the application of low temperatures to preserve the structural and functional integrity of cells and tissues. Conventional cooling protocols allow ice to form and solute concentrations to rise during the cryopreservation process. The damage caused by the rise in solute concentration can be mitigated by the use of compounds known as cryoprotectants. Such compounds protect cells from the consequences of slow cooling injury, allowing them to be cooled at cooling rates which avoid the lethal effects of intracellular ice. An alternative to conventional cooling is vitrification. Vitrification methods incorporate cryoprotectants at sufficiently high concentrations to prevent ice crystallization so that the system forms an amorphous glass thus avoiding the damaging effects caused by conventional slow cooling. However, vitrification too can impose damaging consequences on cells as the cryoprotectant concentrations required to vitrify cells at lower cooling rates are potentially, and often, harmful. While these concentrations can be lowered to nontoxic levels, if the cells are ultra-rapidly cooled, the resulting metastable system can lead to damage through devitrification and growth of ice during subsequent storage and rewarming if not appropriately handled.The commercial and clinical application of stem cells requires robust and reproducible cryopreservation protocols and appropriate long-term, low-temperature storage conditions to provide reliable master and working cell banks. Though current Good Manufacturing Practice (cGMP) compliant methods for the derivation and banking of clinical grade pluripotent stem cells exist and stem cell lines suitable for clinical applications are available, current cryopreservation protocols, whether for vitrification or conventional slow freezing, remain suboptimal. Apart from the resultant loss of valuable product that suboptimal cryopreservation engenders, there is a danger that such processes will impose a selective

  7. Heat diffusion in fractal geometry cooling surface

    Directory of Open Access Journals (Sweden)

    Ramšak Matjaz

    2012-01-01

    Full Text Available In the paper the numerical simulation of heat diffusion in the fractal geometry of Koch snowflake is presented using multidomain mixed Boundary Element Method. The idea and motivation of work is to improve the cooling of small electronic devices using fractal geometry of surface similar to cooling ribs. The heat diffusion is assumed as the only principle of heat transfer. The results are compared to the heat flux of a flat surface. The limiting case of infinite small fractal element is computed using Richardson extrapolation.

  8. Crack-Depth Prediction in Steel Based on Cooling Rate

    Directory of Open Access Journals (Sweden)

    M. Rodríguez-Martín

    2016-01-01

    Full Text Available One criterion for the evaluation of surface cracks in steel welds is to analyze the depth of the crack, because it is an effective indicator of its potential risk. This paper proposes a new methodology to obtain an accurate crack-depth prediction model based on the combination of infrared thermography and the 3D reconstruction procedure. In order to do this, a study of the cooling rate of the steel is implemented through active infrared thermography, allowing the study of the differential thermal behavior of the steel in the fissured zone with respect to the nonfissured zone. These cooling rate data are correlated with the real geometry of the crack, which is obtained with the 3D reconstruction of the welds through a macrophotogrammetric procedure. In this way, it is possible to analyze the correlation between cooling rate and depth through the different zones of the crack. The results of the study allow the establishment of an accurate predictive depth model which enables the study of the depth of the crack using only the cooling rate data. In this way, the remote measure of the depth of the surface steel crack based on thermography is possible.

  9. Surface cooling due to forest fire smoke

    Science.gov (United States)

    Robock, Alan

    1991-11-01

    In four different cases of extensive forest fire smoke the surface temperature effects were determined under the smoke cloud. In all cases, daytime cooling and no nighttime effects were found. The locations of smoke clouds from extensive forest fires in western Canada in 1981 and 1982, in northern China and Siberia in 1987, and in Yellowstone National Park in northwestern Wyoming in 1988 were determined from satellite imagery. As these smoke clouds passed over the midwestern United States for the Canadian and Yellow-stone fires and over Alaska for the Chinese/Siberian fires, surface air temperature effects were determined by comparing actual surface air temperatures with those forecast by model output statistics (MOS) of the United States National Weather Service. MOS error fields corresponding to the smoke cloud locations showed day-time cooling of 1.5° to 7°C under the smoke but no nighttime effects. These results correspond to theoretical estimates of the effects of smoke, and they serve as observational confirmation of a portion of the nuclear winter theory. This also implies that smoke from biomass burning can have a daytime cooling effect of a few degrees over seasonal time scales. In order to properly simulate the present climate with a numerical climate model in regions of regular burning it may be necessary to include this smoke effect.

  10. EFFECT OF COOLING RATES ON THE MICROSTRUCTURE AND ...

    African Journals Online (AJOL)

    ... eutectic under three cooling conditions were proposed. In the DTA mode (slow cooling), the relationship between the two phases was stable. However as the cooling rates increased ( quenching and meltspun modes), the relationship tended towards metastability. KEY WORDS: alloy, solidification, microstructure, eutectic, ...

  11. Cooling the vertical surface by conditionally single pulses

    Directory of Open Access Journals (Sweden)

    Karpov Pavel

    2017-01-01

    Full Text Available You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of “island” film cooling.

  12. Cooling the vertical surface by conditionally single pulses

    Science.gov (United States)

    Karpov, Pavel; Nazarov, Alexander; Serov, Anatoly; Terekhov, Victor

    2017-10-01

    You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency) per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of "island" film cooling.

  13. Effectiveness of hand cooling and a cooling jacket on post-exercise cooling rates in hyperthermic athletes.

    Science.gov (United States)

    Maroni, Tessa; Dawson, Brian; Barnett, Kimberley; Guelfi, Kym; Brade, Carly; Naylor, Louise; Brydges, Chris; Wallman, Karen

    2018-01-24

    This study compared the effects of a hand cooling glove (∼16°C water temperature; subatmospheric pressure of -40 mmHg) and a cooling jacket (CJ) on post-exercise cooling rates (gastrointestinal core temperature, Tc; skin temperature, Tsk) and cognitive performance (the Stroop Colour-Word test). Twelve male athletes performed four trials (within subjects, counterbalanced design) involving cycling at a workload equivalent to 75% ⩒O 2 max in heat (35.7 ± 0.2°C, 49.2 ± 2.6% RH) until a Tc of 39°C or exhaustion occurred. A 30-min cooling period (in 22.3 ± 0.3°C, 42.1 ± 3.6% RH) followed, where participants adopted either one-hand cooling (1H), two-hand cooling (2H), wore a CJ or no cooling (NC). No significant differences were seen in Tc and Tsk cooling rates between trials; however, moderate effect sizes (d = 0.50-0.76) suggested Tc cooling rates to be faster for 1H, 2H and CJ compared to NC after 5 min; 1H and CJ compared to NC after 10 min and for CJ to be faster than 2H at 25-30 min. Reaction times on the cognitive test were similar between all trials after the 30 min cooling/no-cooling period (p > .05). In conclusion, Tc cooling rates were faster with 1H and CJ during the first 10 min compared to NC, with minimal benefit associated with 2H cooling. Reaction time responses were not impacted by the use of the glove(s) or CJ.

  14. Influence of Cooling Rate on Microsegregation Behavior of Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Md. Imran Khan

    2014-01-01

    Full Text Available The effect of cooling rate on microstructure and microsegregation of three commercially important magnesium alloys was investigated using Wedge (V-shaped castings of AZ91D, AM60B, and AE44 alloys. Thermocouples were distributed to measure the cooling rate at six different locations of the wedge casts. Solute redistribution profiles were drawn based on the chemical composition analysis obtained by EDS/WDS analysis. Microstructural and morphological features such as dendrite arm spacing and secondary phase particle size were analyzed using both optical and scanning electron microscopes. Dendritic arm spacing and secondary phase particle size showed an increasing trend with decreasing cooling rate for the three alloys. Area percentage of secondary phase particles decreased with decreasing cooling rate for AE44 alloy. The trend was different for AZ91D and AM60B alloys, for both alloys, area percentage of β-Mg17Al12 increased with decreasing cooling rate up to location 4 and then decreased slightly. The tendency for microsegregation was more severe at slower cooling rates, possibly due to prolonged back diffusion. At slower cooling rate, the minimum concentration of aluminum at the dendritic core was lower compared to faster cooled locations. The segregation deviation parameter and the partition coefficient were calculated from the experimentally obtained data.

  15. Venus Surface Power and Cooling System Design

    Science.gov (United States)

    Landis, Geoffrey A.; Mellott, Kenneth D.

    2004-01-01

    A radioisotope power and cooling system is designed to provide electrical power for the a probe operating on the surface of Venus. Most foreseeable electronics devices and sensors simply cannot operate at the 450 C ambient surface temperature of Venus. Because the mission duration is substantially long and the use of thermal mass to maintain an operable temperature range is likely impractical, some type of active refrigeration may be required to keep certain components at a temperature below ambient. The fundamental cooling requirements are comprised of the cold sink temperature, the hot sink temperature, and the amount of heat to be removed. In this instance, it is anticipated that electronics would have a nominal operating temperature of 300 C. Due to the highly thermal convective nature of the high-density atmosphere, the hot sink temperature was assumed to be 50 C, which provided a 500 C temperature of the cooler's heat rejecter to the ambient atmosphere. The majority of the heat load on the cooler is from the high temperature ambient surface environment on Venus. Assuming 5 cm radial thickness of ceramic blanket insulation, the ambient heat load was estimated at approximately 77 watts. With an estimated quantity of 10 watts of heat generation from electronics and sensors, and to accommodate some level of uncertainty, the total heat load requirement was rounded up to an even 100 watts. For the radioisotope Stirling power converter configuration designed, the Sage model predicts a thermodynamic power output capacity of 478.1 watts, which slightly exceeds the required 469.1 watts. The hot sink temperature is 1200 C, and the cold sink temperature is 500 C. The required heat input is 1740 watts. This gives a thermodynamic efficiency of 27.48 %. The maximum theoretically obtainable efficiency is 47.52 %. It is estimated that the mechanical efficiency of the power converter design is on the order of 85 %, based on experimental measurements taken from 500 watt power

  16. Effect of cooling rate on crystallization in an aluminophosphosilicate melt

    DEFF Research Database (Denmark)

    Liu, S. J.; Zhang, Yanfei; Yue, Yuanzheng

    2011-01-01

    The effect of cooling rate on spontaneous crystallization behavior of an alumino-phospho-silicate melt is studied by means of differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and viscometry. The cooling rates of 160, 2100 and 12000 K/s are attained by subjecting ......, the opalescence of the glass can be tuned by adjusting the cooling rate. This makes the production of opal glasses or transparent glass ceramics more efficient and energy saving, since the conventional isothermal treatment procedure can be left out....... the glass melt to the casting, pressing and fiber-drawing processes, respectively. Results show that phase separation occurs in the melt during cooling, and leads to the internal nucleation and opalescence in the studied glass. The degree of phase separation increases with decreasing the cooling rate. Hence...

  17. Thermal shock resistance behavior of a functionally graded ceramic: Effects of finite cooling rate

    Directory of Open Access Journals (Sweden)

    Zhihe Jin

    2014-01-01

    Full Text Available This work presents a semi-analytical model to explore the effects of cooling rate on the thermal shock resistance behavior of a functionally graded ceramic (FGC plate with a periodic array of edge cracks. The FGC is assumed to be a thermally heterogeneous material with constant elastic modulus and Poisson's ratio. The cooling rate applied at the FGC surface is modeled using a linear ramp function. An integral equation method and a closed form asymptotic temperature solution are employed to compute the thermal stress intensity factor (TSIF. The thermal shock residual strength and critical thermal shock of the FGC plate are obtained using the SIF criterion. Thermal shock simulations for an Al2O3/Si3N4 FGC indicate that a finite cooling rate leads to a significantly higher critical thermal shock than that under the sudden cooling condition. The residual strength, however, is relatively insensitive to the cooling rate.

  18. Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

    Science.gov (United States)

    Salamanca, F.; Georgescu, M.; Mahalov, A.; Moustaoui, M.; Martilli, A.

    2016-10-01

    Assessment of mitigation strategies that combat global warming, urban heat islands (UHIs), and urban energy demand can be crucial for urban planners and energy providers, especially for hot, semi-arid urban environments where summertime cooling demands are excessive. Within this context, summertime regional impacts of cool roof and rooftop solar photovoltaic deployment on near-surface air temperature and cooling energy demand are examined for the two major USA cities of Arizona: Phoenix and Tucson. A detailed physics-based parametrization of solar photovoltaic panels is developed and implemented in a multilayer building energy model that is fully coupled to the Weather Research and Forecasting mesoscale numerical model. We conduct a suite of sensitivity experiments (with different coverage rates of cool roof and rooftop solar photovoltaic deployment) for a 10-day clear-sky extreme heat period over the Phoenix and Tucson metropolitan areas at high spatial resolution (1-km horizontal grid spacing). Results show that deployment of cool roofs and rooftop solar photovoltaic panels reduce near-surface air temperature across the diurnal cycle and decrease daily citywide cooling energy demand. During the day, cool roofs are more effective at cooling than rooftop solar photovoltaic systems, but during the night, solar panels are more efficient at reducing the UHI effect. For the maximum coverage rate deployment, cool roofs reduced daily citywide cooling energy demand by 13-14 %, while rooftop solar photovoltaic panels by 8-11 % (without considering the additional savings derived from their electricity production). The results presented here demonstrate that deployment of both roofing technologies have multiple benefits for the urban environment, while solar photovoltaic panels add additional value because they reduce the dependence on fossil fuel consumption for electricity generation.

  19. Heating and cooling rates and their effects upon heart rate in the ...

    African Journals Online (AJOL)

    The heating and cooling rates of adult Chersina angulata were investigated to ascertain whether these tortoises can physiologically alter their rates of heat exchange. In addition, heart rates were recorded to provide an insight into the control of heat exchange. C. angulata heats significantly faster than it cools. Heart rates ...

  20. Controlled rate cooling of fungi using a stirling cycle freezer.

    Science.gov (United States)

    Ryan, Matthew J; Kasulyte-Creasey, Daiva; Kermode, Anthony; San, Shwe Phue; Buddie, Alan G

    2014-01-01

    The use of a Stirling cycle freezer for cryopreservation is considered to have significant advantages over traditional methodologies including N2 free operation, application of low cooling rates, reduction of sample contamination risks and control of ice nucleation. The study assesses the suitability of an 'N2-free' Stirling Cycle controlled rate freezer for fungi cryopreservation. In total, 77 fungi representing a broad taxonomic coverage were cooled using the N2 free cooler following a cooling rate of -1 degrees C min(-1). Of these, 15 strains were also cryopreserved using a traditional 'N2 gas chamber' controlled rate cooler and a comparison of culture morphology and genomic stability against non-cryopreserved starter cultures was undertaken. In total of 75 fungi survived cryopreservation, only a recalcitrant Basidiomycete and filamentous Chromist failed to survive. No changes were detected in genomic profile after preservation, suggesting that genomic function is not adversely compromised as a result of using 'N2 free' cooling. The results demonstrate the potential of 'N2-free' cooling for the routine cryopreservation of fungi in Biological Resource Centres.

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

    Science.gov (United States)

    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.

  2. Effect of modification and cooling rate on the macrostructure of IN-713C alloy

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-07-01

    Full Text Available The results of investigations of the effect of modification and cooling rate on the macrostructure of castings made from IN-713C nickel superalloy were described. As a modifier, cobalt aluminate CoAl2O4 in composition with aluminium powder and colloidal silica was used. Changes in the cooling rate were obtained by the use of a stepped test piece with the steps of 6, 11, 17 and 23 mm thickness. As a criterion for the evaluation of casting macrostructure, the stereological parameters, like grain count, relative surface area, shape factor, and indeces of the grain size and shape homogeneity, were applied. The modification treatment was observed to change the grain type from columnar to equiaxial. The stereological parameters of the equiaxial grains depended to a great extent on the cooling rate of the individual elements of a cast stepped test piece.

  3. Numerical simulation of cooling rates in vitrification systems used for oocyte cryopreservation.

    Science.gov (United States)

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

    2011-08-01

    Oocyte cryopreservation is of key importance in the preservation and propagation of germplasm. Interest in oocyte cryopreservation has increased in recent years due to the application of assisted reproductive technologies in farm animals such as in vitro fertilization, nuclear transfer and the need for the establishment of ova/gene banks worldwide. However, the cryopreservation of the female gamete has been met with limited success mainly due to its small surface-area:volume ratio. In the past decade, several vitrification devices such as open pulled straws (OPS), fine and ultra fine pipette tips, nylon loops and polyethylene films have been introduced in order to manipulate minimal volumes and achieve high cooling rates. However, experimental comparison of cooling rates presents difficulties mainly because of the reduced size of these systems. To circumvent this limitation, a numerical simulation of cooling rates of various vitrification systems immersed in liquid nitrogen was conducted solving the non-stationary heat transfer partial differential equation using finite element method. Results indicate the nylon loop (Cryoloop®) is the most efficient heat transfer system analyzed, with a predicted cooling rate of 180,000°C/min for an external heat transfer coefficient h= 1000 W/m(2)K when cooling from 20 to -130°C; in contrast, the open pulled straw method (OPS) showed the lowest performance with a cooling rate of 5521°C/min considering the same value of external heat transfer coefficient. Predicted cooling rates of Miniflex® and Cryotop® (polyethylene film system) were 6164 and 37,500°C/min, respectively, for the same heat transfer coefficient. Copyright © 2011. Published by Elsevier Inc.

  4. Soil temperature extrema recovery rates after precipitation cooling

    Science.gov (United States)

    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.

  5. Emperor penguin body surfaces cool below air temperature.

    Science.gov (United States)

    McCafferty, D J; Gilbert, C; Thierry, A-M; Currie, J; Le Maho, Y; Ancel, A

    2013-06-23

    Emperor penguins Aptenodytes forsteri are able to survive the harsh Antarctic climate because of specialized anatomical, physiological and behavioural adaptations for minimizing heat loss. Heat transfer theory predicts that metabolic heat loss in this species will mostly depend on radiative and convective cooling. To examine this, thermal imaging of emperor penguins was undertaken at the breeding colony of Pointe Géologie in Terre Adélie (66°40' S 140° 01' E), Antarctica in June 2008. During clear sky conditions, most outer surfaces of the body were colder than surrounding sub-zero air owing to radiative cooling. In these conditions, the feather surface will paradoxically gain heat by convection from surrounding air. However, owing to the low thermal conductivity of plumage any heat transfer to the skin surface will be negligible. Future thermal imaging studies are likely to yield further insights into the adaptations of this species to the Antarctic climate.

  6. The effect of altering skin-surface cooling speeds on vasoconstriction and shivering thresholds.

    Science.gov (United States)

    Taniguchi, Yoshie; Lenhardt, Rainer; Sessler, Daniel I; Kurz, Andrea

    2011-09-01

    Both core and skin temperatures contribute to steady-state thermoregulatory control. Dynamic thermoregulatory responses trigger aggressive defenses against rapid thermal perturbations. These responses potentially complicate interpretation of thermoregulatory studies and could slow induction of therapeutic hypothermia. We thus tested the hypothesis that rapid external skin-cooling triggers vasoconstriction and shivering at higher mean skin temperatures than slow or moderate rates of skin cooling. Eleven healthy volunteers were cooled at 3 skin-cooling rates using forced air or/and conductive cooling in random order. One day volunteers received slow (≈2°C/h) skin cooling, and on another day, they received both medium (≈4°C/h) and fast (≈6°C/h) skin cooling. An endovascular heat-exchanging catheter maintained core temperature. Fingertip blood flow ≤0.25 mL/min defined onset of vasoconstriction; sustained ≥25% increase in oxygen consumption defined onset of shivering. Results were evaluated with repeated-measures analysis of variance, with P shivering were also comparable: 31.4°C (95% CI: 30.3°C, 32.5°C), 31.5°C (95% CI: 30.2°C, 32.8°C), and 30.7°C (95% CI: 28.9°C, 32.5°C), respectively. Onset of vasoconstriction and shivering occurred at similar mean skin temperatures with all 3 cooling rates. Aggressive surface cooling can thus be used in thermoregulatory studies and for induction of therapeutic hypothermia without provoking dynamic thermoregulatory defenses.

  7. Effect of tropospheric aerosols upon atmospheric infrared cooling rates

    Science.gov (United States)

    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.

  8. The Effect of Wind Velocity on the Cooling Rate of Water

    OpenAIRE

    Shrey Aryan

    2016-01-01

    The effect of wind velocity on the cooling rate of water was investigated by blowing air horizontally over the surface of water contained in a plastic water-bottle cap. The time taken for the temperature to fall to the average of the surrounding and initial temperatures was recorded at different values of wind velocity. It was observed that on increasing the wind velocity, the time taken to achieve average temperature not only decreased but also remained the same after a certain point.

  9. Sea surface cooling in the Northern South China Sea observed using Chinese Sea-wing Underwater Glider measurements

    Science.gov (United States)

    Qiu, C.; Mao, H.; Wu, J.

    2016-02-01

    Based on 26 days of Chinese Seawing underwater Glider measurements and satellite microwave data, we documented cooling of the upper mixed layer of the ocean in response to changes in the wind in the Northern South China Sea (NSCS) from September 19, 2014, to October 15, 2014. The Seawing underwater glider measured 177 profiles of temperature, salinity, and pressure within a 55 km נ55 km area, and reached a depth of 1000 m at a temporal resolution of 4 h. The study area experienced two cooling events, Cooling I and Cooling II, according to their timing. During Cooling I, water temperature at 1m depth (T1) decreased by 1.0°C, and the corresponding satellitederived surface winds increased locally by 4.2 m/s. During Cooling II, T1 decreased sharply by 1.7°C within a period of 4 days; sea surface winds increased by 7 m/s and covered the entire NSCS. The corresponding mixed layer depth (MLD) deepened sharply from 30 m to 60 m during Cooling II, and remained steady during Cooling I. We estimated temperature tendencies using a ML model. High resolution Seawing underwater glider measurements provided an estimation of MLD migration, allowing us to obtain the temporal entrainment rate of cool sub thermocline water. Quantitative analysis confirmed that the entrainment rate and latent heat flux were the two major components that regulated cooling of the ML, and that the Ekman advection and sensible heat flux were small.

  10. Effect of cooling rate on the microstructure and mechanical ...

    Indian Academy of Sciences (India)

    continuous cooling transformation (CCT) diagram. Similar cooling conditions were also applied to tensile ... transformation attributes of the steel is exploited to improve strength upon cooling after deformation. .... automatically recorded on a digital gauge in arbitrary hard- ness number. These values were then converted to ...

  11. Effect of cooling rate on the microstructure and mechanical ...

    Indian Academy of Sciences (India)

    The microstructure and mechanical properties of a low carbon steel containing 30 ppm boron have been investigated. The steel was subjected to various cooling conditions in a thermo-mechanical simulator to generate continuous cooling transformation (CCT) diagram. Similar cooling conditions were also applied to tensile ...

  12. Influence of cooling rate on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2011-09-01

    The manufacture of dental crowns and bridges generates residual stresses within the veneering ceramic and framework during the cooling process. Residual stress is an important factor that control the mechanical behavior of restorations. Knowing the stress distribution within the veneering ceramic as a function of depth can help the understanding of failures, particularly chipping, a well-known problem with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objective of this study is to investigate the cooling rate dependence of the stress profile in veneering ceramic layered on metal and zirconia frameworks. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. The stress profile was measured in bilayered disc samples 20 mm in diameter, with a 0.7 mm thick metal or Yttria-tetragonal-zirconia-polycrystal framework and a 1.5mm thick veneering ceramic. Three different cooling procedures were investigated. The magnitude of the stresses in the surface of the veneering ceramic was found to increase with cooling rate, while the interior stresses decreased. At the surface, compressive stresses were observed in all samples. In the interior, compressive stresses were observed in metal samples and tensile in zirconia samples. Cooling rate influences the magnitude of residual stresses. These can significantly influence the mechanical behavior of metal-and zirconia-based bilayered systems. The framework material influenced the nature of the interior stresses, with zirconia samples showing a less favorable stress profile than metal. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Irrigation Induced Surface Cooling in the Context of Modern and Increased Greenhouse Gas Forcing

    Science.gov (United States)

    Cook, Benjamin I.; Puma, Michael J.; Krakauer, Nir Y.

    2010-01-01

    There is evidence that expected warming trends from increased greenhouse gas (GHG) forcing have been locally masked by irrigation induced cooling, and it is uncertain how the magnitude of this irrigation masking effect will change in the future. Using an irrigation dataset integrated into a global general circulation model, we investigate the equilibrium magnitude of irrigation induced cooling under modern (Year 2000) and increased (A1B Scenario, Year 2050) GHG forcing, using modern irrigation rates in both scenarios. For the modern scenario, the cooling is largest over North America, India, the Middle East, and East Asia. Under increased GHG forcing, this cooling effect largely disappears over North America, remains relatively unchanged over India, and intensifies over parts of China and the Middle East. For North America, irrigation significantly increases precipitation under modern GHG forcing; this precipitation enhancement largely disappears under A1B forcing, reducing total latent heat fluxes and the overall irrigation cooling effect. Over India, irrigation rates are high enough to keep pace with increased evaporative demand from the increased GHG forcing and the magnitude of the cooling is maintained. Over China, GHG forcing reduces precipitation and shifts the region to a drier evaporative regime, leading to a relatively increased impact of additional water from irrigation on the surface energy balance. Irrigation enhances precipitation in the Middle East under increased GHG forcing, increasing total latent heat fluxes and enhancing the irrigation cooling effect. Ultimately, the extent to which irrigation will continue to compensate for the warming from increased GHG forcing will primarily depend on changes in the background evaporative regime, secondary irrigation effects (e.g. clouds, precipitation), and the ability of societies to maintain (or increase) current irrigation rates.

  14. Cooling Effectiveness Measurements for Air Film Cooling of Thermal Barrier Coated Surfaces in a Burner Rig Environment Using Phosphor Thermometry

    Science.gov (United States)

    Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

    2016-01-01

    While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. In this investigation, surface temperature mapping was performed using recently developed Cr-doped GdAlO3 phosphor thermometry. Measurements were performed in the NASA GRC Mach 0.3 burner rig on a TBC-coated plate using a scaled up cooling hole geometry where both the mainstream hot gas temperature and the blowing ratio were varied. Procedures for surface temperature and cooling effectiveness mapping of the air film-cooled TBC-coated surface are described. Applications are also shown for an engine component in both the burner rig test environment as well as an engine afterburner environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

  15. Relationship between cooling rate and microsegregation in bottom-chilled directionally solidified ductile irons

    Directory of Open Access Journals (Sweden)

    Chang W.S.

    2013-01-01

    Full Text Available This study explores the relationship between cooling rate and microsegregation of directionally solidified ductile iron. The unidirectional heat transfer system used in this research is made up of a copper mold kept chilled by circulating water and embedded in the bottom of Furan sand mold. Thermocouples are connected to the computer measuring system to record the cooling curves of the castings at a distance of 0, 30, 60 and 90 mm from the chilled copper mold surface. Alloys including Mn, Cr, Cu, Ni and Ti were added to the specimens. Electron microprobe analysis (EPMA was employed to examine distribution of elements between the dendrite arms and nodular graphite. Results show that unidirectional heat transfer affects directly the solidification mode and microstructure of the casting. The cooling curves reveal that local solidification time increases with increasing distance from the chilled copper mold surface. Different solidification rates with corresponding microstructure and element segregation were observed in the same unidirectionally solidified casting. Local solidification time was closely related to element segregation. The effective segregation coefficient (Keff calculated using the Scheil equation was found to vary, according to the stage of solidification. The actual segregation characteristics of complex alloys generally follow the Scheil equation.

  16. Afforestation in China cools local land surface temperature.

    Science.gov (United States)

    Peng, Shu-Shi; Piao, Shilong; Zeng, Zhenzhong; Ciais, Philippe; Zhou, Liming; Li, Laurent Z X; Myneni, Ranga B; Yin, Yi; Zeng, Hui

    2014-02-25

    China has the largest afforested area in the world (∼62 million hectares in 2008), and these forests are carbon sinks. The climatic effect of these new forests depends on how radiant and turbulent energy fluxes over these plantations modify surface temperature. For instance, a lower albedo may cause warming, which negates the climatic benefits of carbon sequestration. Here, we used satellite measurements of land surface temperature (LST) from planted forests and adjacent grasslands or croplands in China to understand how afforestation affects LST. Afforestation is found to decrease daytime LST by about 1.1 ± 0.5 °C (mean ± 1 SD) and to increase nighttime LST by about 0.2 ± 0.5 °C, on average. The observed daytime cooling is a result of increased evapotranspiration. The nighttime warming is found to increase with latitude and decrease with average rainfall. Afforestation in dry regions therefore leads to net warming, as daytime cooling is offset by nighttime warming. Thus, it is necessary to carefully consider where to plant trees to realize potential climatic benefits in future afforestation projects.

  17. Numerical Investigation of the Flow Dynamics and Evaporative Cooling of Water Droplets Impinging onto Heated Surfaces: An Effective Approach To Identify Spray Cooling Mechanisms.

    Science.gov (United States)

    Chen, Jian-Nan; Zhang, Zhen; Xu, Rui-Na; Ouyang, Xiao-Long; Jiang, Pei-Xue

    2016-09-13

    Numerical investigations of the dynamics and evaporative cooling of water droplets impinging onto heated surfaces can be used to identify spray cooling mechanisms. Droplet impingement dynamics and evaporation are simulated using the presented numerical model. Volume-of-fluid method is used in the model to track the free surface. The contact line dynamics was predicted from a dynamic contact angle model with the evaporation rate predicted by a kinetic theory model. A species transport equation was solved in the gas phase to describe the vapor convection and diffusion. The numerical model was validated by experimental data. The physical effects including the contact angle hysteresis and the thermocapillary effect are analyzed to offer guidance for future numerical models of droplet impingement cooling. The effects of various parameters including surface wettability, surface temperature, droplet velocity, droplet size, and droplet temperature were numerically studied from the standpoint of spray cooling. The numerical simulations offer profound analysis and deep insight into the spray cooling heat transfer mechanisms.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Heat transfer characteristics in closed-loop spray cooling of micro-structured surfaces

    International Nuclear Information System (INIS)

    Zhang Wei; Wang Zhaoliang; Xu Minghai

    2012-01-01

    With water as the working fluid, experiments on the heat transfer characteristics of spray cooling of micro-structured surfaces were performed in a closed loop system. Experimental data were analyzed in the view of the ratio between convective heat transfer and phase change heat transfer. The results indicate that heat transfer is obviously enhanced for micro-channel surfaces relative to the flat surface because of higher phase change heat transfer. For the geometries tested at lower surface temperature, the straight finned surface has the largest heat flux; while at higher surface temperature, the cubic pin finned surface has the largest heat flux. Heat fluxes of all the surfaces grow with increasing flow rates, except for the straight finned surface under lower surface temperature. The ratio of phase change to total heat transfer is bigger than 20% for the flat surface, and higher than 50% for micro-structured surface. Critical heat fluxes of 159.1 W/cm 2 , 120.2 W/cm 2 , and 109.8 W/cm 2 are attained respectively for cubic pin finned, straight finned and flat surfaces when the flow rate is 15.9 mL/min, and the corresponding evaporation efficiency are 96.0%, 72.5%, 67.1%. (authors)

  20. The Effect of Wind Velocity on the Cooling Rate of Water

    Directory of Open Access Journals (Sweden)

    Shrey Aryan

    2016-01-01

    Full Text Available The effect of wind velocity on the cooling rate of water was investigated by blowing air horizontally over the surface of water contained in a plastic water-bottle cap. The time taken for the temperature to fall to the average of the surrounding and initial temperatures was recorded at different values of wind velocity. It was observed that on increasing the wind velocity, the time taken to achieve average temperature not only decreased but also remained the same after a certain point.

  1. Impact of irrigation flow rate and intrapericardial fluid on cooled-tip epicardial radiofrequency ablation.

    Science.gov (United States)

    Aryana, Arash; O'Neill, Padraig Gearoid; Pujara, Deep K; Singh, Steve K; Bowers, Mark R; Allen, Shelley L; d'Avila, André

    2016-08-01

    The optimal irrigation flow rate (IFR) during epicardial radiofrequency (RF) ablation has not been established. This study specifically examined the impact of IFR and intrapericardial fluid (IPF) accumulation during epicardial RF ablation. Altogether, 452 ex vivo RF applications (10 g for 60 seconds) delivered to the epicardial surface of bovine myocardium using 3 open-irrigated ablation catheters (ThermoCool SmartTouch, ThermoCool SmartTouch-SF, and FlexAbility) and 50 in vivo RF applications delivered (ThermoCool SmartTouch-SF) in 4 healthy adult swine in the presence or absence of IPF were examined. Ex vivo, RF was delivered at low (≤3 mL/min), reduced (5-7 mL/min), and high (≥10 mL/min) IFRs using intermediate (25-35 W) and high (35-45 W) power. In vivo, applications were delivered (at 9.3 ± 2.2 g for 60 seconds at 39 W) using reduced (5 mL/min) and high (15 mL/min) IFRs. Ex vivo, surface lesion diameter inversely correlated with IFR, whereas maximum lesion diameter and depth did not differ. While steam pops occurred more frequently at low IFR using high power (ThermoCool SmartTouch and ThermoCool SmartTouch-SF), tissue disruption was rare and did not vary with IFR. In vivo, charring/steam pop was not detected. Although there were no discernible differences in lesion size with IFR, surface lesion diameter, maximum diameter, depth, and volume were all smaller in the presence of IPF at both IFRs. Cooled-tip epicardial RF ablation created using reduced IFRs (5-7 mL/min) yields lesion sizes similar to those created using high IFRs (≥10 mL/min) without an increase in steam pop/tissue disruption, whereas the presence of IPF significantly reduces the lesion size. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  2. Effect of cooling rates on the weld heat affected zone coarse grain microstructure

    Directory of Open Access Journals (Sweden)

    Roman Celin

    2018-04-01

    Full Text Available The effect of a cooling rate on the S690Q quenched and tempered steel welded joint coarse grain heat affected zone microstructure was investigated using a dilatometer with controlled heating and cooling fixture. Steel samples were heated to a peak temperature of 1350 °C and cooled at the different cooling time Dt8/5. A dilatometric analysis and hardness measurements of the simulated thermal cycle coarse grain samples were done. Transformation start and finish temperature were determined using dilatation vs. temperature data analysis. The microstructure of the sample with a cooling time 5 s consists of martensite, whereas at cooling time 80 s a bainitic microstructure was observed. The investigated steel cooling cycle using simulation approach makes possible to determine the range of an optimum CG HAZ cooling time for the welding.

  3. Influence of the cooling liquid on surface quality characteristics in milling

    Science.gov (United States)

    Tampu, N. C.; Brabie, G.; Chirita, B. A.; Herghelegiu, E.; Radu, M. C.

    2015-11-01

    Cooling system and cooling liquid characteristics are among the main factors influencing surface quality and tool wear. The aim of this study is to analyse the effect of the cooling liquid, used in different concentrations and at different temperatures, on the quality of the surface layer processed by milling. In order to make this analysis a Minimum Quantity Lubrication (MQL) cooling device is used. Three different volumetric ratios were used to modify the concentration of the cooling fluid (25% water to 75% emulsion, 50% water to 50% emulsion, 75% water to 25% emulsion) and three different temperatures. The studies revealed that surface roughness can be correlated with the variation of the cooling liquid temperature while surface flatness can be correlated to both, cooling liquid temperature and concentration.

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

    Science.gov (United States)

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

    1979-01-01

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

  5. Leidenfrost drops cooling surfaces: theory and interferometric measurement

    NARCIS (Netherlands)

    Van Limbeek, Michiel A. J.; Klein Schaarsberg, Martin H.; Sobac, Benjamin; Rednikov, Alexey; Sun, Chao; Colinet, Pierre; Lohse, Detlef

    2017-01-01

    When a liquid drop is placed on a highly superheated surface, it can be levitated by its own vapour. This remarkable phenomenon is referred to as the Leidenfrost effect. The thermally insulating vapour film results in a severe reduction of the heat transfer rate compared to experiments at lower

  6. Rapid induction of therapeutic hypothermia using convective-immersion surface cooling: safety, efficacy and outcomes.

    Science.gov (United States)

    Howes, Daniel; Ohley, William; Dorian, Paul; Klock, Cathy; Freedman, Robert; Schock, Robert; Krizanac, Danica; Holzer, Michael

    2010-04-01

    Therapeutic hypothermia has become an accepted part of post-resuscitation care. Efforts to shorten the time from return of spontaneous circulation to target temperature have led to the exploration of different cooling techniques. Convective-immersion uses a continuous shower of 2 degrees C water to rapidly induce hypothermia. The primary purpose of this multi-center trial was to evaluate the feasibility and speed of convective-immersion cooling in the clinical environment. The secondary goal was to examine the impact of rapid hypothermia induction on patient outcome. 24 post-cardiac arrest patients from 3 centers were enrolled in the study; 22 agreed to participate until the 6-month evaluations were completed. The median rate of cooling was 3.0 degrees C/h. Cooling times were shorter than reported in previous studies. The median time to cool the patients to target temperature (<34 degrees C) was 37 min (range 14-81 min); and only 27 min in a subset of patients sedated with propofol. Survival was excellent, with 68% surviving to 6 months; 87% of survivors were living independently at 6 months. Conductive-immersion surface cooling using the ThermoSuit System is a rapid, effective method of inducing therapeutic hypothermia. Although the study was not designed to demonstrate impact on outcomes, survival and neurologic function were superior to those previously reported, suggesting comparative studies should be undertaken. Shortening the delay from return of spontaneous circulation to hypothermic target temperature may significantly improve survival and neurologic outcome and warrants further study. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

  7. Comprehensive study of flow and heat transfer at the surface of circular cooling fin

    Science.gov (United States)

    Mityakov, V. Yu; Grekov, M. A.; Gusakov, A. A.; Sapozhnikov, S. Z.; Seroshtanov, V. V.; Bashkatov, A. V.; Dymkin, A. N.; Pavlov, A. V.; Milto, O. A.; Kalmykov, K. S.

    2017-11-01

    For the first time is proposed to combine heat flux measurements with thermal imaging and PIV (particle image velocimetry) for a comprehensive study of flow and heat transfer at the surface of the circular cooling fin. The investigated hollow fin is heated from within with saturated water steam; meanwhile the isothermal external surface simulates one of the perfect fin. Flow and heat transfer at the surface of the solid fin of the same size and shape, made of titanium alloy is investigated in the same regimes. Gradient Heat Flux Sensors (GHFS) were installed at different places of the fin surface. Velocity field around a cylinder, temperature field at the surface of the fin and heat flux for each rated time were obtained. Comprehensive method including heat flux measurement, PIV and thermal imaging allow to study flow and heat transfer at the surface of the fin in real time regime. The possibility to study flow and heat transfer for non-isothermal fins is shown; it is allow to improve traditional calculation of the cooling fins.

  8. Radiative cooling test facility and performance evaluation of 4-MIL aluminized polyvinyl fluoride and white-paint surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kruskopf, M.S.; Berdahl, P.; Martin, M.; Sakkal, F.; Sobolewski, M.

    1980-11-01

    A test facility designed to measure the amount of radiative cooling a specific material or assembly of materials will produce when exposed to the sky is described. Emphasis is placed upon assemblies which are specifically designed to produce radiative cooling and which therefore offer promise for the reduction of temperatures and/or humidities in occupied spaces. The hardware and software used to operate the facility are documented and the results of the first comprehensive experiments are presented. A microcomputer-based control/data acquisition system was employed to study the performance of two prototype radiator surfaces: 4-mil aluminized polyvinyl fluoride (PVF) and white painted surfaces set below polyethylene windscreens. The cooling rates for materials tested were determined and can be approximated by an equation (given). A computer model developed to simulate the cooling process is presented. (MCW)

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

    Science.gov (United States)

    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.

  10. Effect of Cooling Rate on Microstructures and Mechanical Properties in SA508 Gr4N High Strength Low Alloy Steel

    International Nuclear Information System (INIS)

    Kim, Minchul; Park, Sanggyu; Choi, Kwonjae; Lee, Bongsang

    2013-01-01

    The microstructure of Ni-Cr-Mo low alloy steel is a mixture of tempered martensite and tempered lower bainite and that of Mn-Mo-Ni low alloy steel is predominantly tempered upper bainite. Higher strength and toughness steels are very attractive as an eligible RPV steel, so several researchers have studied to use the Ni-Cr-Mo low alloy steel for the NPP application. Because of the thickness of reactor vessel, there are large differences in austenitizing cooling rates between the surface and the center locations of thickness in RPV. Because the cooling rates after austenitization determine the microstructure, it would affect the mechanical properties in Ni-Cr-Mo low alloy steel, and it may lead to inhomogeneous characteristics when the commercial scale of RPV is fabricated. In order to apply the Ni-Cr-Mo low alloy steel to RPV, it is necessary to evaluate the changes of microstructure and mechanical properties with varying phase fractions in Ni-Cr-Mo low alloy steel. In this study, the effects of martensite and bainite fractions on mechanical properties in Ni-Cr-Mo low alloy steel were examined by controlling the cooling rate after austenitization. First of all, continuous cooling transformation(CCT) diagram was established from the dilatometric analyses. Then, the phase fractions at each cooling rate were quantitatively evaluated. Finally, the mechanical properties were correlated with the phase fraction, especially fraction of martensite in Ni-Cr-Mo low alloy steel

  11. Nonpharmacologic Approach to Minimizing Shivering During Surface Cooling: A Proof of Principle Study1

    Science.gov (United States)

    Shah, Nirav G.; Cowan, Mark J.; Pickering, Edward; Sareh, Houtan; Afshar, Majid; Fox, Dawn; Marron, Jennifer; Davis, Jennifer; Herold, Keith; Shanholtz, Carl B.; Hasday, Jeffrey D.

    2012-01-01

    Purpose This study had two objectives: (1) to quantify the metabolic response to physical cooling in febrile patients with Systemic Inflammatory Response Syndrome (SIRS); and (2) to provide proof for the hypothesis that the efficiency of external cooling and the subsequent shivering response are influenced by site and temperature of surface cooling pads. Methods To quantify shivering thermogenesis during surface cooling for fever, we monitored oxygen consumption (VO2) in six febrile patients with SIRS during conventional cooling with cooling blankets and ice packs. To begin to determine how location and temperature of surface cooling influences shivering, we compared 5 cooling protocols for inducing mild hypothermia in six healthy volunteers. Results In the SIRS patients, core temperature decreased 0.67°C per hour, all patients shivered, VO2 increased 57.6% and blood pressure increased 15% during cooling. In healthy subjects, cooling with the 10°C vest was most comfortable and removed heat most efficiently without shivering or VO2 increase. Cooling with combined vest and thigh pads stimulated the most shivering and highest VO2, and increased core temperature. Reducing vest temperature from 10°C to 5°C failed to increase heat removal secondary to cutaneous vasoconstriction. Capsaicin, an agonist for TRPV1 warm-sensing channels, partially reversed this effect in 5 subjects. Conclusions Our results identify the hazards of surface cooling in febrile critically ill patients and support the concept that optimization of cooling pad temperature and position may improve cooling efficiency and reduce shivering. PMID:22762936

  12. Nonpharmacologic approach to minimizing shivering during surface cooling: a proof of principle study.

    Science.gov (United States)

    Shah, Nirav G; Cowan, Mark J; Pickering, Edward; Sareh, Houtan; Afshar, Majid; Fox, Dawn; Marron, Jennifer; Davis, Jennifer; Herold, Keith; Shanholtz, Carl B; Hasday, Jeffrey D

    2012-12-01

    This study had 2 objectives: (1) to quantify the metabolic response to physical cooling in febrile patients with systemic inflammatory response syndrome (SIRS) and (2) to provide proof for the hypothesis that the efficiency of external cooling and the subsequent shivering response are influenced by site and temperature of surface cooling pads. To quantify shivering thermogenesis during surface cooling for fever, we monitored oxygen consumption (VO(2)) in 6 febrile patients with SIRS during conventional cooling with cooling blankets and ice packs. To begin to determine how location and temperature of surface cooling influence shivering, we compared 5 cooling protocols for inducing mild hypothermia in 6 healthy volunteers. In the patients with SIRS, core temperature decreased 0.67 °C per hour, all patients shivered, VO(2) increased 57.6%, and blood pressure increased 15% during cooling. In healthy subjects, cooling with the 10 °C vest was most comfortable and removed heat most efficiently without shivering or VO(2) increase. Cooling with combined vest and thigh pads stimulated the most shivering and highest VO(2) and increased core temperature. Reducing vest temperature from 10 °C to 5 °C failed to increase heat removal secondary to cutaneous vasoconstriction. Capsaicin, an agonist for the transient receptor potential cation channel subfamily V member 1 (TRPV1) warm-sensing channels, partially reversed this effect in 5 subjects. Our results identify the hazards of surface cooling in febrile critically ill patients and support the concept that optimization of cooling pad temperature and position may improve cooling efficiency and reduce shivering. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Modification of n-Si Characteristics by Annealing and Cooling at Different Rates

    Directory of Open Access Journals (Sweden)

    Subhi K. Salih

    2003-01-01

    for samples annealed at lower than 550°C. For samples annealed at higher temperatures, quenching gave better dark-current density vs. potential plots. SEM measurements showed parallel results to these findings. Enhanced surface textures were observed for slowly cooled wafers from temperatures below 550°C. Samples quenched from temperatures above 550°C showed better surfaces than slowly cooled counterparts.

  14. Effect of cooling rate during hot stamping on low cyclic fatigue of boron steel sheet

    Science.gov (United States)

    Suh, Chang Hee; Jang, Won Seok; Oh, Sang Kyun; Lee, Rac Gyu; Jung, Yun-Chul; Kim, Young Suk

    2012-08-01

    Boron steel is widely used throughout the automobile industry due to its high tensile strength and hardenability. When boron steel is used for body parts, only high strength is required for crashworthiness. However, when boron steel is used for chassis parts, a high fatigue life is needed. The microstructure of boron steel is mainly affected by the cooling rate during hot stamping. Therefore, this study investigated the low cyclic fatigue life according to the cooling rate. The fatigue life increased at a low strain amplitude when the cooling rate was fast. However, at a high strain amplitude, the fatigue life decreased, due to the low ductility and fracture toughness of the martensite formed by rapid cooling. Martensite formed by a fast cooling rate shows excellent fatigue life at a low total strain amplitude; however, a multiphase microstructure formed by a slow cooling rate is recommended if the parts experience high and low total strain amplitudes alternately. In addition, the cooling rate has little effect on the distribution of solute boron and boron precipitations, so it is expected that boron rarely affects low cyclic fatigue.

  15. Method for controlling a coolant liquid surface of cooling system instruments in an atomic power plant

    International Nuclear Information System (INIS)

    Monta, Kazuo.

    1974-01-01

    Object: To prevent coolant inventory within a cooling system loop in an atomic power plant from being varied depending on loads thereby relieving restriction of varied speed of coolant flow rate to lowering of a liquid surface due to short in coolant. Structure: Instruments such as a superheater, an evaporator, and the like, which constitute a cooling system loop in an atomic power plant, have a plurality of free liquid surface of coolant. Portions whose liquid surface is controlled and portions whose liquid surface is varied are adjusted in cross-sectional area so that the sum total of variation in coolant inventory in an instrument such as a superheater provided with an annulus portion in the center thereof and an inner cylindrical portion and a down-comer in the side thereof comes equal to that of variation in coolant inventory in an instrument such as an evaporator similar to the superheater. which is provided with an overflow pipe in its inner cylindrical portion or down-comer, thereby minimizing variation in coolant inventory of the entire coolant due to loads thus minimizing variation in varied speed of the coolant. (Kamimura, M.)

  16. Measurements of solar and terrestrial heating and cooling rate profiles in Arctic and sub-tropic stratocumulus

    Science.gov (United States)

    Gottschalk, Matthias; Lauermann, Felix; Ehrlich, André; Siebert, Holger; Wendisch, Manfred

    2017-04-01

    Stratocumulus covers approximately 20 % (annually averaged) of the Earth's surface and thus strongly influences the atmospheric and surface radiative energy budget resulting in radiative cooling and heating effects. Globally, the solar cooling effect of the widespread sub-tropical stratocumulus dominates. However, in the Arctic the solar cloud albedo effect (cooling) is often smaller than the thermal-infrared greenhouse effect (warming), which is a result of the lower incoming solar radiation and the low cloud base height. Therefore, Arctic stratocumulus mostly warms the atmosphere and surface below the cloud. Additionally, different environmental conditions lead to differences between sub-tropical and Arctic stratocumulus. Broadband pyranometers and pyrgeometers will be used to measure heating and cooling rate profiles in and above stratocumulus. For this purpose two slowly moving platforms are used (helicopter and tethered balloon) in order to consider for the long response times of both broadband radiation sensors. Two new instrument packages are developed for the applied tethered balloon and helicopter platforms, which will be operated within Arctic and sub-tropical stratocumulus, respectively. In June 2017, the balloon will be launched from a sea ice floe north of 80 °N during the Arctic Balloon-borne profiling Experiment (ABEX) as part of (AC)3 (Arctic Amplification: Climate Relevant Atmospheric and Surface Processes and Feedback Mechanisms) Transregional Collaborative Research Center. The helicopter will sample sub-tropical stratocumulus over the Azores in July 2017.

  17. Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Phosphor Thermometry

    Science.gov (United States)

    Eldridge, Jeffrey I.

    2016-01-01

    While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness for jet engine components are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. Phosphor thermometry offers several advantages for mapping temperatures of air film cooled surfaces. While infrared thermography has been typically applied to study air film cooling effectiveness, temperature accuracy depends on knowing surface emissivity (which may change) and correcting for effects of reflected radiation. Because decay time-based full-field phosphor thermometry is relatively immune to these effects, it can be applied advantageously to temperature mapping of air film-cooled TBC-coated surfaces. In this presentation, an overview will be given of efforts at NASA Glenn Research Center to perform temperature mapping of air film-cooled TBC-coated surfaces in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and the strengths and limitations of this method for studying air film cooling effectiveness are discussed.

  18. Influence of veneering porcelain thickness and cooling rate on residual stresses in zirconia molar crowns.

    Science.gov (United States)

    Al-Amleh, Basil; Neil Waddell, J; Lyons, Karl; Swain, Michael V

    2014-03-01

    The aim of this study was to investigate the influence of increasing veneering porcelain thickness in clinically representative zirconia molar crowns on the residual stresses under fast and slow cooling protocols. Six veneered zirconia copings (Procera, Nobel Biocare AB, Gothenburg, Sweden) based on a mandibular molar form, were divided into 3 groups with flattened cusp heights that were 1mm, 2mm, or 3mm. Half the samples were fast cooled during final glazing; the other half were slow cooled. Vickers indentation technique was used to determine surface residual stresses. Normality distribution within each sample was done using Kolmogorov-Smirnov & Shapiro-Wilk tests, and one-way ANOVA tests used to test for significance between various cusp heights within each group. Independent t-tests used to evaluate significance between each cusp height group with regards to cooling. Compressive stresses were recorded with fast cooling, while tensile stresses with slow cooling. The highest residual compressive stresses were recorded on the fast cooled 1mm cusps which was significantly higher than the 2 and 3mm fast cooled crowns (Pcrown anatomy have substantially different effects on residual stress profiles with increasing veneering porcelain thickness compared to the basic flat plate model. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Estimation of the amount of surface contamination of a water cooled nuclear reactor by cooling water analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, G. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary)]. E-mail: nagyg@sunserv.kfki.hu; Somogyi, A. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary); Patek, G. [Paks Nuclear Power Plant, P.O. Box 71, Paks H-7031 (Hungary); Pinter, T. [Paks Nuclear Power Plant, P.O. Box 71, Paks H-7031 (Hungary); Schiller, R. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary)

    2007-06-15

    Calculations, based upon on-the-spot measurements, were performed to estimate the contamination of NPP primary circuit and spent fuel storage pool solid surfaces via the composition of the cooling water in connection with a non-nuclear incident in the Paks NPP. Thirty partially burnt-up fuel element bundles were damaged during a cleaning process, an incident which resulted in the presence of fission products in the cooling water of the cleaning tank (CT) situated in a separate pool (P1). Since this medium was in contact for an extended period of time with undamaged fuel elements to be used later and also with other structural materials of the spent fuel storage pool (SP), it was imperative to assess the surface contamination of these latter ones with a particular view to the amount of fission material. In want of direct methods, one was restricted to indirect information which rested mainly on the chemical and radiochemical data of the cooling water. It was found that (i) the most important contaminants were uranium, plutonium, cesium and cerium; (ii) after the isolation of P1 and SP and an extended period of filtering the only important contaminants were uranium and plutonium; (iii) the surface contamination of the primary circuit (PC) was much lower than that of either SP or P1; (iv) some 99% of the contamination was removed from the water by the end of the filtering process.

  20. The impact of cooling rates on the microstructure of Al-U alloys

    International Nuclear Information System (INIS)

    Munitz, A.; Zenou, V.Y.; Cotler, C.; Talyanker, M.

    1997-01-01

    The impact of cooling rates on the microstructure of Al-U alloys was studied by optical, scanning electron, and transmission electron microscopy. A variety of solidification techniques were employed to obtain cooling rates ranging between 3 x 10 -2 and 10 6 K/s. High-purity uranium (99.9 pct) and high-purity aluminum (99.99 pct), or commercially pure type Al-1050 aluminum alloys were used to prepare Al-U alloys with U concentration ranging between 3 and 22 wt pct. The U concentration at which a coupled eutectic growth was observed depends on the cooling rates imposed during solidification and ranged from 13.8 wt pct for the slower cooling rates to more than 22 wt pct for the fastest cooling rates. The eutectic morphology and its distribution depends on the type of aluminum used in preparing the alloys and on the cooling rates during solidification. The eutectic in alloys prepared from pure aluminum was evenly distributed, while for those prepared from Al-1050, the eutectic was unevenly distributed, with eutectic colonies of up to 3 mm in diameter. Two lamellar eutectic structures were observed in alloys prepared from pure aluminum containing more than 18 wt pct U, which solidified by cooling rates of about 10 K/s. One structure consisted of the stable eutectic between UAl 4 and Al lamella. The other structure consisted of a metastable eutectic between UAl 3 and Al lamella. At least three different eutectic morphologies were observed in alloys prepared from Al-1050

  1. The impact of cooling rates on the microstructure of Al-U alloys

    Energy Technology Data Exchange (ETDEWEB)

    Munitz, A.; Zenou, V.Y.; Cotler, C. [Nuclear Research Center-Negev, Beer-Sheva (Israel); Talyanker, M. [Ben-Gurion Univ. of the Negev, Beer-Sheva (Israel). Dept. of Materials Engineering

    1997-04-01

    The impact of cooling rates on the microstructure of Al-U alloys was studied by optical, scanning electron, and transmission electron microscopy. A variety of solidification techniques were employed to obtain cooling rates ranging between 3 {times} 10{sup {minus}2} and 10{sup 6} K/s. High-purity uranium (99.9 pct) and high-purity aluminum (99.99 pct), or commercially pure type Al-1050 aluminum alloys were used to prepare Al-U alloys with U concentration ranging between 3 and 22 wt pct. The U concentration at which a coupled eutectic growth was observed depends on the cooling rates imposed during solidification and ranged from 13.8 wt pct for the slower cooling rates to more than 22 wt pct for the fastest cooling rates. The eutectic morphology and its distribution depends on the type of aluminum used in preparing the alloys and on the cooling rates during solidification. The eutectic in alloys prepared from pure aluminum was evenly distributed, while for those prepared from Al-1050, the eutectic was unevenly distributed, with eutectic colonies of up to 3 mm in diameter. Two lamellar eutectic structures were observed in alloys prepared from pure aluminum containing more than 18 wt pct U, which solidified by cooling rates of about 10 K/s. One structure consisted of the stable eutectic between UAl{sub 4} and Al lamella. The other structure consisted of a metastable eutectic between UAl{sub 3} and Al lamella. At least three different eutectic morphologies were observed in alloys prepared from Al-1050.

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

    Science.gov (United States)

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

    2012-11-01

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

  3. Experimental determination of surface heat transfer coefficient in a dry ice-ethanol cooling bath using a numerical approach.

    Science.gov (United States)

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

    BACKGROUND: Dry ice-ethanol bath (-78 degree C) have been widely used in low temperature biological research to attain rapid cooling of samples below freezing temperature. The prediction of cooling rates of biological samples immersed in dry ice-ethanol bath is of practical interest in cryopreservation. The cooling rate can be obtained using mathematical models representing the heat conduction equation in transient state. Additionally, at the solid cryogenic-fluid interface, the knowledge of the surface heat transfer coefficient (h) is necessary for the convective boundary condition in order to correctly establish the mathematical problem. The study was to apply numerical modeling to obtain the surface heat transfer coefficient of a dry ice-ethanol bath. A numerical finite element solution of heat conduction equation was used to obtain surface heat transfer coefficients from measured temperatures at the center of polytetrafluoroethylene and polymethylmetacrylate cylinders immersed in a dry ice-ethanol cooling bath. The numerical model considered the temperature dependence of thermophysical properties of plastic materials used. A negative linear relationship is observed between cylinder diameter and heat transfer coefficient in the liquid bath, the calculated h values were 308, 135 and 62.5 W/(m 2 K) for PMMA 1.3, PTFE 2.59 and 3.14 cm in diameter, respectively. The calculated heat transfer coefficients were consistent among several replicates; h in dry ice-ethanol showed an inverse relationship with cylinder diameter.

  4. On the cooling rate of strip cast ingots for sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.Q. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yan, M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mse_yanmi@dial.zju.edu.cn; Wu, J.M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Luo, W. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Cui, X.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Ying, H.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2007-04-30

    Effects of the cooling rate of strip cast ingots on magnetic properties of sintered NdFeB magnets were studied. It is found that the magnetic properties greatly depend on wheel speed due to different alloy microstructures, which affect readily the particle size distribution of powders obtained after the subsequent jet milling. At higher cooling rate, interlamellar spacing between Nd-rich platelets of the alloy was small, resulting in a lower saturated magnetization due to increased amounts of small particles after jet milling. With further decreasing cooling rate, the resultant larger interlamellar spacing led to too large particle sizes as well as a more irregular shape; thus deteriorated the magnetic properties of the final magnet. A model was developed to disclose the effects of particle sizes on the magnetic alignment process. In the current investigation, optimum magnetic properties of the final magnets were obtained with a cooling rate of 2.6 m/s for preparing the strip. The magnets made by conventionally cast ingot technique exhibited the lowest magnetic properties because of the slowest cooling rate.

  5. Predicting temperature drop rate of mass concrete during an initial cooling period using genetic programming

    Science.gov (United States)

    Bhattarai, Santosh; Zhou, Yihong; Zhao, Chunju; Zhou, Huawei

    2018-02-01

    Thermal cracking on concrete dams depends upon the rate at which the concrete is cooled (temperature drop rate per day) within an initial cooling period during the construction phase. Thus, in order to control the thermal cracking of such structure, temperature development due to heat of hydration of cement should be dropped at suitable rate. In this study, an attempt have been made to formulate the relation between cooling rate of mass concrete with passage of time (age of concrete) and water cooling parameters: flow rate and inlet temperature of cooling water. Data measured at summer season (April-August from 2009 to 2012) from recently constructed high concrete dam were used to derive a prediction model with the help of Genetic Programming (GP) software “Eureqa”. Coefficient of Determination (R) and Mean Square Error (MSE) were used to evaluate the performance of the model. The value of R and MSE is 0.8855 and 0.002961 respectively. Sensitivity analysis was performed to evaluate the relative impact on the target parameter due to input parameters. Further, testing the proposed model with an independent dataset those not included during analysis, results obtained from the proposed GP model are close enough to the real field data.

  6. A gas-cooled reactor surface power system

    International Nuclear Information System (INIS)

    Lipinski, R.J.; Wright, S.A.; Lenard, R.X.; Harms, G.A.

    1999-01-01

    A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life-cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitride clad in Nb1%Zr, which has been extensively tested under the SP-100 program. The fuel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fuel and stabilizing the geometry against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian air. The amount of radioactivity in the reactor at launch is very small (less than a Curie, and about equal to a truckload of uranium ore). The system will need to be engineered so that criticality can not occur for any launch accident. This system is also adaptable for electric propulsion or life-support during transit to and from Mars. copyright 1999 American Institute of Physics

  7. A gas-cooled reactor surface power system

    International Nuclear Information System (INIS)

    Lipinski, Ronald J.; Wright, Steven A.; Lenard, Roger X.; Harms, Gary A.

    1999-01-01

    A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life-cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitride clad in Nb1%Zr, which has been extensively tested under the SP-100 program. The fuel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fuel and stabilizing the geometry against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian air. The amount of radioactivity in the reactor at launch is very small (less than a Curie, and about equal to a truckload of uranium ore). The system will need to be engineered so that criticality can not occur for any launch accident. This system is also adaptable for electric propulsion or life-support during transit to and from Mars

  8. A Gas-Cooled Reactor Surface Power System

    Energy Technology Data Exchange (ETDEWEB)

    Harms, G.A.; Lenard, R.X.; Lipinski, R.J.; Wright, S.A.

    1998-11-09

    A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life- cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitide clad in Nb 1 %Zr, which has been extensively tested under the SP-I 00 program The fiel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fbel and stabilizing the geometty against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian air. The amount of radioactivity in the reactor at launch is very small (less than a Curie, and about equal to a truckload of uranium ore). The system will need to be engineered so that criticality cannot occur for any launch accident. This system is also adaptable for electric propulsion or life-support during transit to and from Mars.

  9. Near-ground cooling efficacies of trees and high-albedo surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen Michael [Univ. of California, Berkeley, CA (United States)

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequentlyproposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object’s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by 0.25 perturbs the object’s surface temperature by -1 to +2 K. Comparing a tree’s canopy-to-air convection to the reduction in ground-to-air convection induced by tree shading of the ground indicates that the presence of a tree can either increase or decrease solar heating of ground-level air. The tree’s net effect depends on the extent to which solar heating of the canopy is dissipated by evaporation, and on the fraction of air heated by the canopy that flows downward and mixes with the ground-level air. A two-month lysimeter (plant-weighing) experiment was conducted to measure instantaneous rates of water loss from a tree under various conditions of weather and soil-moisture. Calculations of canopy-to-air convection and the reduction of ground-to-air convection based on this data indicate that canopy-induced heating would negate shadowinduced cooling if approximately 45% of the canopy-heated air mixed with ground level air. This critical fraction is comparable to typical downward mixing

  10. Effect of modification and cooling rate on the microstructure of IN-713C alloy

    Directory of Open Access Journals (Sweden)

    A. Kościelna

    2009-10-01

    Full Text Available The results of investigations of the effect of modification and cooling rate on the microstructure of castings made from IN-713C nickel superalloy were described. As an inoculant, cobalt aluminate CoAl2O4 in composition with aluminium powder and colloidal silica was used. Changes in the cooling rate were obtained by the use of cast stepped test piece with steps of 6, 11 and 17 mm thickness. The phase and chemical composition of microstructural constituents, i.e. of γ phase, γ’ phase and eutectic carbide precipitates, was evaluated. A significant effect of the cooling rate and modification treatment on the stereological parameters of carbide precipitates was confirmed. Problems in evaluation of the chemical composition of these precipitates in the case of a high degree of the structure refinement were indicated.

  11. Influence of cooling rate on microstructure of NdFeB strip casting flakes

    Energy Technology Data Exchange (ETDEWEB)

    Binglin Guo; Bo Li; Dongling Wang; Xiaojun Yu [Central Iron and Steel Research Inst., Beijing, BJ (China); Jifan Hu [Shandong Univ., Jinan (China)

    2005-07-01

    In this paper, flakes of NdFeB cast alloys were prepared by using the strip casting technique. Microstructure and composition of phases in NdFeB SC flakes were studied by SEM and energy spectra. Especially, the influences of cooling rate on the microstructure of SC flakes were discussed, helping us to master strip casting technology. The results show that the cooling rate plays an important role in obtaining the perfect microstructure of SC flakes, which thickness is supposed not less than 0.32mm in these studies. (orig.)

  12. Effect of modification and cooling rate on the microstructure of IN-713C alloy

    OpenAIRE

    A. Kościelna; J. Śleziona; F. Binczyk

    2009-01-01

    The results of investigations of the effect of modification and cooling rate on the microstructure of castings made from IN-713C nickel superalloy were described. As an inoculant, cobalt aluminate CoAl2O4 in composition with aluminium powder and colloidal silica was used. Changes in the cooling rate were obtained by the use of cast stepped test piece with steps of 6, 11 and 17 mm thickness. The phase and chemical composition of microstructural constituents, i.e. of γ phase, γ’ phase and eutec...

  13. An experimental study of two-phase multiple jet cooling on finned surfaces using a dielectric fluid

    International Nuclear Information System (INIS)

    Chien, Liang-Han; Chang, Chin-Yao

    2011-01-01

    In the present study, a multiple jet-cooling device for electronic components was investigated, using FC-72 as the working fluid. The nozzle plate, located 5 mm above the 12 x 12 mm 2 test surface, had 5 or 9 pores of 0.24 mm in diameter. The test surfaces included a smooth surface, two pin-finned surfaces and two straight-finned surfaces of 400 or 800 μm fin height, 200 or 400 μm fin thickness and gap width. The results showed that the heat transfer performance increased with increasing flow rate or increasing surface area enhancement ratio. The pin-finned surface of 800 μm fin height, 200 μm fin thickness and gap width yielded the best performance, which was about 250% greater than the smooth surface at 150 ml/min. Correlations of two-phase multiple jets, cooling in free and submerged states, are proposed based on the data at 50 o C saturation temperature, in the range of Re = 1655-8960, Bo = 0.024-0.389, area enhancement ratio = 1.0-5.32, jet spacing-diameter ratio (S/d) = 13.7 and 20.6. The root mean square deviation of the prediction is 11.96% for the free jet data, and 9.08% for the submerged jet data. Thermal resistance of the best surface varied between 0.1 and 0.13 K/W at 150 ml/min flow rate in the range of 60-120 W heat input. - Highlights: → We investigated the performance of two-phase FC-72 multiple jet-cooling device. → Smaller jet spacing, larger fin height/width ratio resulted in greater cooling rate. → The pin-fins of 0.8 mm fin height, 0.2 mm thickness yielded the best performance. → The criterion of the submerged jet and free jet is obtained. → Correlations of two-phase jets, cooling in free and submerged states, are provided.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cavallo, Dario, E-mail: Dario.cavallo@unige.it [University of Genoa, Dept. of Chemistry and Industrial Chemistry, Via Dodecaneso 31, 16146 Genoa (Italy); Portale, Giuseppe [ESRF, Dubble CRG, Netherlands Organization of Scientific Research (NWO), 38043 Grenoble (France); Androsch, René [Martin-Luther-University Halle-Wittenberg, Center of Engineering Sciences, D-06099 Halle/S. (Germany)

    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.

  15. The Cool Surfaces of Binaries Near-Earth Asteroids

    NARCIS (Netherlands)

    Delbo, Marco; Walsh, K.; Mueller, M.

    2008-01-01

    We present results from thermal-infrared observations of binary near-Earth asteroids (NEAs). These objects, in general, have surface temperatures cooler than the average values for non-binary NEAs. We discuss how this may be evidence of higher-than-average surface thermal inertia. The comparison of

  16. Two strategies of lowering surface deformations of internally cooled X-ray optics

    International Nuclear Information System (INIS)

    Oberta, P.; Áč, V.; Hrdý, J.

    2013-01-01

    Internally cooled X-ray optics, like X-ray monochromators and reflecting X-ray mirrors, play a crucial role in defining a beamlines resolution, degree of coherence and flux. A great effort is invested in the development of these optical components. An important aspect of the functionality of high heat load optics is its cooling and its influence on surface deformation. The authors present a study of two different geometrical cooling approaches. Its influence on beam inhomogeneity due to the strain from the manufacturing process is presented. X-ray topographic images and FWHM measurements are presented. FEA simulations of cooling efficiency and surface deformations were performed. The best achieved results are under an enlargement of 0.4μrad of the measured rocking curve

  17. Processes setting the characteristics of sea surface cooling induced by tropical cyclones

    OpenAIRE

    Vincent, E.M.; Lengaigne, Matthieu; Madec, G.; Vialard, Jérôme; Samson, G.; Jourdain, N.C.; Menkès, Christophe; Jullien, S.

    2012-01-01

    A 1/2 degrees resolution global ocean general circulation model is used to investigate the processes controlling sea surface cooling in the wake of tropical cyclones (TCs). Wind forcing related to more than 3000 TCs occurring during the 1978-2007 period is blended with the CORE II interannual forcing, using an idealized TC wind pattern with observed magnitude and track. The amplitude and spatial characteristics of the TC-induced cooling are consistent with satellite observations, with an aver...

  18. Automatic control system of brain temperature by air-surface cooling for therapeutic hypothermia.

    Science.gov (United States)

    Utsuki, T

    2013-01-01

    An automatic control system of brain temperature by air-surface cooling was developed for therapeutic hypothermia, which is increasingly recommended for hypoxic-ischemic encephalopathy after cardiac arrest and neonatal asphyxia in several guidelines pertinent to resuscitation. Currently, water-surface cooling is the most widespread cooling method in therapeutic hypothermia. However, it requires large electric power for precise control and also needs water-cooling blankets which have potential for compression of patients by its own weight and for water leakage in ICU. Air-surface cooling does not have such problems and is more suitable for clinical use than water-surface cooling, because air has lower specific heat and density as well as the impossibility of the contamination in ICU by its leakage. In the present system, brain temperature of patients is automatically controlled by suitable adjustment of the temperature of the air blowing into the cooling blankets. This adjustment is carried out by the regulation of mixing cool and warm air using proportional control valves. The computer in the developed control apparatus suitably calculates the air temperature and rotation angle of the valves every sampling time on the basis of the optimal-adaptive control algorithm. Thus, the proposed system actualizes automatic control of brain temperature by the inputting only the clinically desired temperature of brain. The control performance of the suggested system was verified by the examination using the mannequin in substitution for an adult patient. In the result, the control error of the head temperature of the mannequin was 0.12 °C on average in spite of the lack of the production capacity of warm air after the re-warming period. Thus, this system serves as a model for the clinically applied system.

  19. Optimization of Cooling Water Flow Rate in Nuclear and Thermal Power Plants Based on a Mathematical Model of Cooling Systems1

    International Nuclear Information System (INIS)

    Murav’ev, V. P.; Kochetkov, A. V.; Glazova, E. G.

    2016-01-01

    A mathematical model and algorithms are proposed for automatic calculation of the optimum flow rate of cooling water in nuclear and thermal power plants with cooling systems of arbitrary complexity. An unlimited number of configuration and design variants are assumed with the possibility of obtaining a result for any computational time interval, from monthly to hourly. The structural solutions corresponding to an optimum cooling water flow rate can be used for subsequent engineering-economic evaluation of the best cooling system variant. The computerized mathematical model and algorithms make it possible to determine the availability and degree of structural changes for the cooling system in all stages of the life cycle of a plant.

  20. Cooling of a channeled lava flow with non-Newtonian rheology: crust formation and surface radiance

    Directory of Open Access Journals (Sweden)

    Stefano Santini

    2011-12-01

    Full Text Available We present here the results from dynamical and thermal models that describe a channeled lava flow as it cools by radiation. In particular, the effects of power-law rheology and of the presence of bends in the flow are considered, as well as the formation of surface crust and lava tubes. On the basis of the thermal models, we analyze the assumptions implicit in the currently used formulae for evaluation of lava flow rates from satellite thermal imagery. Assuming a steady flow down an inclined rectangular channel, we solve numerically the equation of motion by the finite-volume method and a classical iterative solution. Our results show that the use of power-law rheology results in relevant differences in the average velocity and volume flow rate with respect to Newtonian rheology. Crust formation is strongly influenced by power-law rheology; in particular, the growth rate and the velocity profile inside the channel are strongly modified. In addition, channel curvature affects the flow dynamics and surface morphology. The size and shape of surface solid plates are controlled by competition between the shear stress and the crust yield strength: the degree of crust cover of the channel is studied as a function of the curvature. Simple formulae are currently used to relate the lava flow rate to the energy radiated by the lava flow as inferred from satellite thermal imagery. Such formulae are based on a specific model, and consequently, their validity is subject to the model assumptions. An analysis of these assumptions reveals that the current use of such formulae is not consistent with the model.

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

    Science.gov (United States)

    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

  2. Evaluation of Cryoprotectant and Cooling Rate for Sperm Cryopreservation in the Euryhaline Fish Medaka Oryzias latipes

    Science.gov (United States)

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

    2017-01-01

    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 (Me2SO), N, N- dimethylacetamide (DMA), N, N,-dimethyl formamide (DMF), and glycerol with concentrations of 5, 10, and 15% for 60 min 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 30 min; Me2SO, DMA, and DMF (10 and 15%) and glycerol (5, 10 and 15%) significantly decreased the motility of sperm within 1 min after mixing. Based on these results, methanol and ME were selected as cryoprotectants (10%) to evaluate with different cooling rates (from 5 °C/min to 25 °C/min) and were compared to Me2SO 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 Me2SO, 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

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

    Science.gov (United States)

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

    2011-01-01

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

  4. Effects of Cooling Rate on 6.5% Silicon Steel Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jun [Ames Lab. and Iowa State Univ., Ames, IA (United States); Macziewski, Chad [Iowa State Univ., Ames, IA (United States); Jensen, Brandt [Ames Lab., Ames, IA (United States); Ouyang, Gaoyuan [Iowa State Univ., Ames, IA (United States); Zhou, Lin [Ames Lab., Ames, IA (United States); Dennis, Kevin [Ames Lab., Ames, IA (United States); Zarkevich, Nikolai [Ames Lab., Ames, IA (United States); Jiang, Xiujuan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tang, Wei [Ames Lab., Ames, IA (United States); Zhou, Shihuai [Ames Lab., Ames, IA (United States); Simsek, Emrah [Ames Lab., Ames, IA (United States); Napolitano, Ralph [Iowa State Univ., Ames, IA (United States); Kramer, Matt [Ames Lab., Ames, IA (United States)

    2017-03-02

    Increasing Si content improves magnetic and electrical properties of electrical steel, with 6.5% Si as the optimum. Unfortunately, when Si content approaches 5.7%, the Fe-Si alloy becomes brittle. At 6.5%, the steel conventional cold rolling process is no longer applicable. The heterogeneous formation of B2 and D03 ordered phases is responsible for the embrittlement. The formation of these ordered phases can be impeded by rapid cooling. However, only the cooling rates of water and brine water were investigated. A comprehensive study of the effect of rapid cooling rate on the formation of the ordered phases was carried out by varying wheel speed and melt-injection rate. Thermal imaging employed to measure cooling rates while microstructures of the obtained ribbons are characterized using X-ray diffraction and TEM. The electrical, magnetic and mechanical properties are characterized using 4-pt probe, VSM, and macro-indentation methods. The relations between physical properties and ordered phases are established.

  5. Numerical model of crustal accretion and cooling rates of fast-spreading mid-ocean ridges

    Directory of Open Access Journals (Sweden)

    P. Machetel

    2013-10-01

    Full Text Available We designed a thermo-mechanical numerical model for fast-spreading mid-ocean ridge with variable viscosity, hydrothermal cooling, latent heat release, sheeted dyke layer, and variable melt intrusion possibilities. The model allows for modulating several accretion possibilities such as the "gabbro glacier" (G, the "sheeted sills" (S or the "mixed shallow and MTZ lenses" (M. These three crustal accretion modes have been explored assuming viscosity contrasts of 2 to 3 orders of magnitude between strong and weak phases and various hydrothermal cooling conditions depending on the cracking temperatures value. Mass conservation (stream-function, momentum (vorticity and temperature equations are solved in 2-D cartesian geometry using 2-D, alternate direction, implicit and semi-implicit finite-difference scheme. In a first step, an Eulerian approach is used solving iteratively the motion and temperature equations until reaching steady states. With this procedure, the temperature patterns and motions that are obtained for the various crustal intrusion modes and hydrothermal cooling hypotheses display significant differences near the mid-ocean ridge axis. In a second step, a Lagrangian approach is used, recording the thermal histories and cooling rates of tracers travelling from the ridge axis to their final emplacements in the crust far from the mid-ocean ridge axis. The results show that the tracer's thermal histories are depending on the temperature patterns and the crustal accretion modes near the mid-ocean ridge axis. The instantaneous cooling rates obtained from these thermal histories betray these discrepancies and might therefore be used to characterize the crustal accretion mode at the ridge axis. These deciphering effects are even more pronounced if we consider the average cooling rates occurring over a prescribed temperature range. Two situations were tested at 1275–1125 °C and 1050–850 °C. The first temperature range covers mainly the

  6. Thermal impact of waste emplacement and surface cooling associated with geologic disposal of nuclear waste

    International Nuclear Information System (INIS)

    Wang, J.S.Y.; Mangold, D.C.; Spencer, R.K.; Tsang, C.F.

    1982-01-01

    The age of nuclear waste - the length of time between its removal from the reactor cores and its emplacement in a repository - is a significant factor in determining the thermal loading of a repository. The surface cooling period as well as the density and sequence of waste emplacement affects both the near-field repository structure and the far-field geologic environment. To investigate these issues, a comprehensive review was made of the available literature pertaining to thermal effects and thermal properties of mined geologic repositories. This included a careful evaluation of the effects of different surface cooling periods of the wastes, which is important for understanding the optimal thermal loading of a repository. The results led to a clearer understanding of the importance of surface cooling in evaluating the overall thermal effects of a radioactive waste repository. The principal findings from these investigations are summarized in this paper

  7. Influence of Cooling Lubricants on the Surface Roughness and Energy Efficiency of the Cutting Machine Tools

    Science.gov (United States)

    Jersák, J.; Simon, S.

    2017-08-01

    The Technical University of Liberec and Brandenburg University of Technology Cottbus-Senftenberg investigated the influence of cooling lubricants on the surface roughness and energy efficiency of cutting machine tools. After summarizing the achieved experimental results, the authors conclude that cooling lubricants extensively influence the cutting temperature, cutting forces and energy consumption. Also, it is recognizable that cooling lubricants affect the cutting tools lifetime and the workpiece surface quality as well. Furthermore, costs of these cooling lubricants and the related environmental burden need to be considered. A current trend is to reduce the amount of lubricants that are used, e.g., when the Minimum Quantity Lubrication (MQL) technique is applied. The lubricant or process liquid is thereby transported by the compressed air in the form of an aerosol to the contact area between the tool and workpiece. The cutting process was monitored during testing by the three following techniques: lubricant-free cutting, cutting with the use of a lubricant with the MQL technique, and only utilizing finish-turning and finish-face milling. The research allowed the authors to monitor the cutting power and mark the achieved surface quality in relation to the electrical power consumption of the cutting machine. In conclusions, the coherence between energy efficiency of the cutting machine and the workpiece surface quality regarding the used cooling lubricant is described.

  8. Influence of Cooling Lubricants on the Surface Roughness and Energy Efficiency of the Cutting Machine Tools

    Directory of Open Access Journals (Sweden)

    Jersák J.

    2017-08-01

    Full Text Available The Technical University of Liberec and Brandenburg University of Technology Cottbus-Senftenberg investigated the influence of cooling lubricants on the surface roughness and energy efficiency of cutting machine tools. After summarizing the achieved experimental results, the authors conclude that cooling lubricants extensively influence the cutting temperature, cutting forces and energy consumption. Also, it is recognizable that cooling lubricants affect the cutting tools lifetime and the workpiece surface quality as well. Furthermore, costs of these cooling lubricants and the related environmental burden need to be considered. A current trend is to reduce the amount of lubricants that are used, e.g., when the Minimum Quantity Lubrication (MQL technique is applied. The lubricant or process liquid is thereby transported by the compressed air in the form of an aerosol to the contact area between the tool and workpiece. The cutting process was monitored during testing by the three following techniques: lubricant-free cutting, cutting with the use of a lubricant with the MQL technique, and only utilizing finish-turning and finish-face milling. The research allowed the authors to monitor the cutting power and mark the achieved surface quality in relation to the electrical power consumption of the cutting machine. In conclusions, the coherence between energy efficiency of the cutting machine and the workpiece surface quality regarding the used cooling lubricant is described.

  9. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    Science.gov (United States)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  10. Effect of cooling rate on shear bond strength of veneering porcelain to a zirconia ceramic material.

    Science.gov (United States)

    Komine, Futoshi; Saito, Ayako; Kobayashi, Kazuhisa; Koizuka, Mai; Koizumi, Hiroyasu; Matsumura, Hideo

    2010-12-01

    The purpose of the present study was to evaluate the effect of cooling rates after firing procedures of veneering porcelain on shear bond strength between veneering porcelain and a zirconium dioxide (zirconia; ZrO₂) ceramic material. A total of 48 ZrO₂ disks were divided equally into three groups. Two veneering porcelains that are recommended for ZrO₂ material - Cerabien ZR (CZR), IPS e.max Ceram (EMX) - and one that is recommended for metal ceramics - Super Porcelain AAA (AAA) were assessed. Each group was then further divided into two subgroups (n = 8) according to cooling time (0 or 4 min) after porcelain firing. Specimens were fabricated by veneering the porcelain on the ZrO₂ disks, after which shear bond testing was conducted. Bond strength differed significantly by cooling time in ZrO₂-AAA (P veneering porcelain to a zirconia material depending on porcelain material used.

  11. Influence of cryogenic cooling rate on mechanical properties of tool steels

    Science.gov (United States)

    Mazor, G.; Ladizhensky, I.; Shapiro, A.

    2017-09-01

    The effect of the rapid cryogenic treatment on hardness and wear resistance of several kinds of tool steel was examined. Two ways of cryogenic cooling were evaluated: direct immersion of the metallic samples into liquid nitrogen and three-stage rapid cryogenic cooling (1 - precooling in LN2 to -20°C, 2 - formation on the sample of a frost layer from air by natural humidity, 3 - second cooling of the frost-covered sample in LN2 to -195.7°C). Material in “as is” conditions and after a preliminary heat treatment (850°C) were used as the reference points. The HV microhardness and the wear rate under dry abrasive friction were evaluated. Despite the very different types of the examined metals’ nature, microstructure, and hardening mechanisms, the rapid cryogenic cooling improves both the hardness and the wear resistance values. For all investigated metals rapid cryogenic cooling assisted with the frost layer produces the best results.

  12. Analysis of the Effect of Cooling Intensity Under Volume-Surface Hardening on Formation of Hardened Structures in Steel 20GL

    Science.gov (United States)

    Evseev, D. G.; Savrukhin, A. V.; Neklyudov, A. N.

    2018-01-01

    Computer simulation of the kinetics of thermal processes and structural and phase transformations in the wall of a bogie side frame produced from steel 20GL is performed with allowance for the differences in the cooling intensity under volume-surface hardening. The simulation is based on the developed method employing the diagram of decomposition of austenite at different cooling rates. The data obtained are used to make conclusion on the effect of the cooling intensity on propagation of martensite structure over the wall section.

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

    Science.gov (United States)

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

    2016-10-01

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

  14. Investigation the solidification of Al-4.8 wt.%Cu alloy at different cooling rate by computer-aided cooling curve analysis

    Directory of Open Access Journals (Sweden)

    Mehdi Dehnavi

    2014-07-01

    Full Text Available Depending on the casting conditions and alloy composition, microstructure and properties of the aluminium alloys will be different. There are many techniques available for investigating the solidification of metals and alloys. In recent years computer-aided cooling curve analysis (CA-CCA has been used to determine thermophysical properties of alloys, latent heat and solid fraction. The aim of this study was to investigate the effect of cooling rate on the structural features of Al-4.8 wt.%Cu alloy by thermal analysis of cooling curves. To do this, Al-4.8 wt.%Cu alloy was melted and solidified applying 0.04, 0.42, and 1.08 °C/sec cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. It was found that the formation temperatures of various thermal parameters such as (liquidus, solidus and eutectic temperatures are shifting by increasing of cooling rate from 0.04 °C/sec to 1.08 °C/sec. The structural results show that grain size and secondary dendrite arm spacing decreased by increasing of cooling rate.

  15. Extra- and intra-cellular ice formation of red seabream (Pagrus major) embryos at different cooling rates.

    Science.gov (United States)

    Li, J; Zhang, L L; Liu, Q H; Xu, X Z; Xiao, Z Z; Ma, D Y; Xu, S H; Xue, Q Z

    2009-08-01

    The ice crystal formation is assumed as the most lethal factor for the failure of fish embryo cryopreservation and intracellular ice formation (IIF) plays a central role in cell injury during cooling. The objectives were to observe the morphological changes of red seabream (Pagrus major) embryo during the cooling-thawing process, and to examine the effect of cryoprotectant and cooling rate on the temperatures of oil globule ice formation (T(OIF)), extra-cellular ice formation (T(EIF)) and intracellular ice formation (T(IIF)) using cryomicroscope. After thawing, the morphological changes of embryos were observed and recorded by the video attachment and monitor under the microscope. During the cooling process, three representative phenomena were observed: oil globule gradually turned bright firstly, then the whole field of view flashed and the embryo blackened. Cooling rate affect the temperature of both extra- and intra-cellular ice formations. T(EIF) and T(IIF) at high cooling rate were much lower than that at low cooling rate. And the value of T(EIF)-T(IIF) increased from 0.45 to 11.11 degrees C with the increase of cooling rate from 3 to130 degrees C/min. Taken together, our results suggested that high cooling rate with proper cryoprotectant would be a good option for red seabream embryo cryopreservation.

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

    Science.gov (United States)

    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

  17. Screened Thermonuclear Reaction Rates on Magnetar Surfaces

    International Nuclear Information System (INIS)

    Hong-Lin, Liu; Zhi-Quan, Luo; Jing-Jing, Liu; Xiang-Jun, Lai

    2008-01-01

    Improving Salpeter's method, we discuss the effect of superstrong magnetic fields (such as those of magnetars) on thermonuclear reaction rates. These most interesting reactions, including the hydrogen burning by the CNO cycle and the helium burning by the triple alpha reaction, are investigated as examples on the magnetar surfaces. The obtained result shows that the superstrong magnetic fields can increase the thermonuclear reaction rates by many orders of magnitude. The enhancement may have significant influence for further study research of the magnetars, especially for the x-ray luminosity observation and the evolution of magnetars. (geophysics, astronomy, and astrophysics)

  18. Thermal impact of waste emplacement and surface cooling associated with geologic disposal of nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.S.Y.; Mangold, D.C.; Spencer, R.K.; Tsang, C.F.

    1982-08-01

    The thermal effects associated with the emplacement of aged radioactive wastes in a geologic repository were studied, with emphasis on the following subjects: the waste characteristics, repository structure, and rock properties controlling the thermally induced effects; the current knowledge of the thermal, thermomechanical, and thermohydrologic impacts, determined mainly on the basis of previous studies that assume 10-year-old wastes; the thermal criteria used to determine the repository waste loading densities; and the technical advantages and disadvantages of surface cooling of the wastes prior to disposal as a means of mitigating the thermal impacts. The waste loading densities determined by repository designs for 10-year-old wastes are extended to older wastes using the near-field thermomechanical criteria based on room stability considerations. Also discussed are the effects of long surface cooling periods determined on the basis of far-field thermomechanical and thermohydrologic considerations. The extension of the surface cooling period from 10 years to longer periods can lower the near-field thermal impact but have only modest long-term effects for spent fuel. More significant long-term effects can be achieved by surface cooling of reprocessed high-level waste.

  19. Austenite – ferrite transformation temperature regression equations for low carbon steels with cooling rate account

    Science.gov (United States)

    Záhumenský, P.; Kohútek, I.; Semeňák, J.

    2017-12-01

    The austenite-ferrite transformation temperatures evaluated by dilatometry using thermo-mechanical simulator Gleeble 1500D are investigated in this paper. The effect of cooling rates 1, 5, 10 and 15°C/s on the upper and lower critical transformation temperatures was evaluated for 30 specimens of six material groups. Considering the cooling rate from dilatometry tests and chemical composition (C ≤ 0.2%, Mn ≤ 2%, Si ≤ 0.26%) of particular specimens, the regression equations for both transformation temperatures were derived. These relations have to be satisfied to avoid the crack formation during continuous casting, as well as to provide the hot rolling control. The proposed regression equations are compared with 32 similar ones adopted from 1961 to 2017 and exhibit a good conformity and accuracy.

  20. Effects of the Cooling Rate After Annealing Treatment on the Microstructure and the Mechanical Properties of Super-Duplex Stainless Steel

    International Nuclear Information System (INIS)

    Kwon, Gi-Hyoun; Park, Yong-Ho; Na, Young-Sang; Yoo, Wee-Do; Lee, Jong-Hoon

    2012-01-01

    The aim of this study was to analyze the effect of the cooling rate after heat treatment on the microstructure and mechanical properties of 2507 duplex stainless steels. Heat treatment was carried out at 1050°C for 1 hr, followed by controlled cooling. The cooling rates were 175.6 × 10 - 3°C/s, 47.8 × 10 - 3°C/s, 33.3 × 10 - 3°C/s, 16.7 × 10 - 3°C/s, 11.7 × 10 - 3°C/s, 5.8 × 10 - 3°C/s and 2.8 × 10 - 3°C/s, which resulted in variations of the microstructure, such as the fractional change of the ferrite phase and sigma phase formation. Fatigue, hardness, impact and tensile tests were performed on the specimens with different cooling rates. The precipitation of the σ phase caused a hardness increase and a sharp decrease of toughness and tensile elongation. The fatigue limit of the sample with a cooling rate of 5.8 × 10 - 3°C/s was 26 MPa higher than that of the sample with a cooling rate of 175.6 × 10 - 3°C/s. Our observations of the fracture surface confirmed that the higher fatigue resistance of the specimen with a cooling rate of 5.8 × 10 - 3°C/s was caused by the delay of the fatigue crack growth, in addition to higher yield strength.

  1. Effects of the Cooling Rate After Annealing Treatment on the Microstructure and the Mechanical Properties of Super-Duplex Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Gi-Hyoun; Park, Yong-Ho [Pusan National University, Pusan (Korea, Republic of); Na, Young-Sang; Yoo, Wee-Do; Lee, Jong-Hoon [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2012-10-15

    The aim of this study was to analyze the effect of the cooling rate after heat treatment on the microstructure and mechanical properties of 2507 duplex stainless steels. Heat treatment was carried out at 1050°C for 1 hr, followed by controlled cooling. The cooling rates were 175.6 × 10{sup -}3°C/s, 47.8 × 10{sup -}3°C/s, 33.3 × 10{sup -}3°C/s, 16.7 × 10{sup -}3°C/s, 11.7 × 10{sup -}3°C/s, 5.8 × 10{sup -}3°C/s and 2.8 × 10{sup -}3°C/s, which resulted in variations of the microstructure, such as the fractional change of the ferrite phase and sigma phase formation. Fatigue, hardness, impact and tensile tests were performed on the specimens with different cooling rates. The precipitation of the σ phase caused a hardness increase and a sharp decrease of toughness and tensile elongation. The fatigue limit of the sample with a cooling rate of 5.8 × 10{sup -}3°C/s was 26 MPa higher than that of the sample with a cooling rate of 175.6 × 10{sup -}3°C/s. Our observations of the fracture surface confirmed that the higher fatigue resistance of the specimen with a cooling rate of 5.8 × 10{sup -}3°C/s was caused by the delay of the fatigue crack growth, in addition to higher yield strength.

  2. Quantitative theoretical analysis of lifetimes and decay rates relevant in laser cooling BaH

    Science.gov (United States)

    Moore, Keith; Lane, Ian C.

    2018-05-01

    Tiny radiative losses below the 0.1% level can prove ruinous to the effective laser cooling of a molecule. In this paper the laser cooling of a hydride is studied with rovibronic detail using ab initio quantum chemistry in order to document the decays to all possible electronic states (not just the vibrational branching within a single electronic transition) and to identify the most populated final quantum states. The effect of spin-orbit and associated couplings on the properties of the lowest excited states of BaH are analysed in detail. The lifetimes of the A2Π1/2, H2Δ3/2 and E2Π1/2 states are calculated (136 ns, 5.8 μs and 46 ns respectively) for the first time, while the theoretical value for B2 Σ1/2+ is in good agreement with experiments. Using a simple rate model the numbers of absorption-emission cycles possible for both one- and two-colour cooling on the competing electronic transitions are determined, and it is clearly demonstrated that the A2Π - X2Σ+ transition is superior to B2Σ+ - X2Σ+ , where multiple tiny decay channels degrade its efficiency. Further possible improvements to the cooling method are proposed.

  3. Enhancement of Nucleate Boiling Heat Flux on Macro/Micro-Structured Surfaces Cooled by Multiple Impinging Jets

    Science.gov (United States)

    Kugler, Scott Lee

    1997-01-01

    An experimental investigation of nucleate boiling heat transfer from modified surfaces cooled by multiple in-line impinging circular jets is reported and found to agree with single jet results. A copper block is heated from the back by two electrical arcs, and cooled on the opposite side by three identical liquid jets of distilled water at subcoolings of 25 C 50 C and 77 C and Freon 113 at 24 C subcooling. Liquid flow rates are held constant at 5, 10, and 15 GPH for each of the three jets with jet velocities ranging from 1.4 m/s to 1 1.2 m/s and jet diameters from 0.95 mm to 2.2 mm. To increase the maximum heat flux (CHF) and heat removal rate, the boiling surface was modified by both macro and micro enhancements. Macro modification consists of machined radial grooves in the boiling surface arranged in an optimally designed pattern to allow better liquid distribution along the surface. These grooves also reduce splashing of liquid droplets, and provide 'channels' to sweep away bubbles. Micro modification was achieved by flame spraying metal powder on the boiling surface, creating a porous, sintered surface. With the addition of both micro and macro structured enhancements, maximum heat flux and nucleate boiling can be enhanced by more than 200%. Examination of each surface modification separately and together indicates that at lower superheats, the micro structure provides the enhanced heat transfer by providing more nucleation sites, while for higher superheats the macro structure allows better liquid distribution and bubble removal. A correlation is presented to account for liquid subcoolings and surface enhancements, in addition to the geometrical and fluid properties previously reported in the literature.

  4. Influence of the post-annealing cooling rate on the superconducting and mechanical properties of LFZ textured Bi-2212 rods

    International Nuclear Information System (INIS)

    Natividad, E; Gomez, J A; Angurel, L A; Salazar, A; Pastor, J Y; Llorca, J

    2002-01-01

    Laser floating zone textured Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) thin rods were manufactured and subjected to a two-step annealing process at 870 deg C and 801 deg C in air. It was found that the subsequent cooling process led to marked changes in electrical properties. Three cooling rates were tested: (i) quenching in liquid nitrogen, (ii) cooling in air inside an alumina tube and (iii) cooling inside the furnace. The results showed that the faster the cooling rate, the higher the normal state resistivity. The T c distribution across the rods was also affected by the cooling rate, but no large differences were observed in the magnitude of the critical current at 77 K since the homogeneity of furnace-cooled samples compensated for the higher outer J c values of fast-cooled ones. The mechanical properties (elastic modulus and flexure strength) were not influenced by the cooling rate, but the samples quenched in liquid nitrogen were often cracked by thermal shock. The elastic modulus and the flexure strength of the rods were deteriorated by the existence of an outer ring of compact, poorly textured material and by the large bubbles found in the central region of the rod. Samples processed by a two-step texturing process which reduced the thickness of the outer ring and eliminated the bubbles had better electrical and mechanical properties

  5. Influence of the post-annealing cooling rate on the superconducting and mechanical properties of LFZ textured Bi-2212 rods

    CERN Document Server

    Natividad, E; Angurel, L A; Salazar, A; Pastor, J Y; Llorca, J

    2002-01-01

    Laser floating zone textured Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub + subdelta (Bi-2212) thin rods were manufactured and subjected to a two-step annealing process at 870 deg C and 801 deg C in air. It was found that the subsequent cooling process led to marked changes in electrical properties. Three cooling rates were tested: (i) quenching in liquid nitrogen, (ii) cooling in air inside an alumina tube and (iii) cooling inside the furnace. The results showed that the faster the cooling rate, the higher the normal state resistivity. The T sub c distribution across the rods was also affected by the cooling rate, but no large differences were observed in the magnitude of the critical current at 77 K since the homogeneity of furnace-cooled samples compensated for the higher outer J sub c values of fast-cooled ones. The mechanical properties (elastic modulus and flexure strength) were not influenced by the cooling rate, but the samples quenched in liquid nitrogen were often cracked by thermal shock. The elastic m...

  6. Sperm cryopreservation of the Indian major carp, Labeo calbasu: effects of cryoprotectants, cooling rates and thawing rates on egg fertilization.

    Science.gov (United States)

    Nahiduzzaman, Md; Hassan, Md Mahbubul; Roy, Pankoz Kumar; Hossain, Md Akhtar; Hossain, Mostafa Ali Reza; Tiersch, Terrence R

    2012-12-01

    A sperm cryopreservation protocol for the Indian major carp, Labeo calbasu, was developed for long-term preservation and artificial fertilization. Milt collected from mature male fish were placed in Alsever's solution (296mOsmolkg(-1)) to immobilize the sperm. Cryoprotectant toxicity was evaluated by motility assessment with dimethyl sulfoxide (DMSO) and methanol at 5, 10 and 15% concentrations. DMSO was more toxic at higher concentrations than methanol, and consequently 15% DMSO was excluded from further study. A one-step cooling protocol (from 5 to 80°C) with two cooling rates (5 and 10°C/min) was carried out in a computer-controlled freezer (FREEZE CONTROL(®) CL-3300; Australia). Based on post-thaw motility, the 10°C/min cooling rate with either 10% DMSO or 10% methanol yielded significantly higher (P=0.011) post-thaw motility than the other rate and cryoprotectant concentrations. Sperm thawed at 40°C for 15s and fresh sperm were used to fertilize freshly collected L. calbasu eggs and significant differences were observed (P=0.001) in percent fertilization between cryopreserved and fresh sperm as well as among different sperm-to-egg ratios (P=0.001). The highest fertilization and hatching rates were observed for thawed sperm at a sperm-to-egg ratio of 4.1×10(5):1. The cryopreservation protocol developed can facilitate hatchery operations and long-term conservation of genetic resources of L. calbasu. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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. © 2015 Wiley Periodicals, Inc.

  9. Carbon-based nanostructured surfaces for enhanced phase-change cooling

    Science.gov (United States)

    Selvaraj Kousalya, Arun

    To maintain acceptable device temperatures in the new generation of electronic devices under development for high-power applications, conventional liquid cooling schemes will likely be superseded by multi-phase cooling solutions to provide substantial enhancement to the cooling capability. The central theme of the current work is to investigate the two-phase thermal performance of carbon-based nanostructured coatings in passive and pumped liquid-vapor phase-change cooling schemes. Quantification of the critical parameters that influence thermal performance of the carbon nanostructured boiling surfaces presented herein will lead to improved understanding of the underlying evaporative and boiling mechanisms in such surfaces. A flow boiling experimental facility is developed to generate consistent and accurate heat transfer performance curves with degassed and deionized water as the working fluid. New means of boiling heat transfer enhancement by altering surface characteristics such as surface energy and wettability through light-surface interactions is explored in this work. In this regard, carbon nanotube (CNT) coatings are exposed to low-intensity irradiation emitted from a light emitting diode and the subcooled flow boiling performance is compared against a non-irradiated CNT-coated copper surface. A considerable reduction in surface superheat and enhancement in average heat transfer coefficient is observed. In another work involving CNTs, the thermal performance of CNT-integrated sintered wick structures is evaluated in a passively cooled vapor chamber. A physical vapor deposition process is used to coat the CNTs with varying thicknesses of copper to promote surface wetting with the working fluid, water. Thermal performance of the bare sintered copper powder sample and the copper-functionalized CNT-coated sintered copper powder wick samples is compared using an experimental facility that simulates the capillary fluid feeding conditions of a vapor chamber

  10. Deposition of boron on fuel rod surface under sub-cooled boiling conditions-An approach toward understanding AOA occurrence

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Asakura, Yamato; Suzuki, Hiroaki

    2011-01-01

    Highlights: → AOA is one of key issues for maintaining stable PWR operation. → AOA is caused by boron accumulation on fuel rods under sub-cooled boiling. → Unstable depositing boron was seldom measured on fuel rods. → MED model was originally developed for crud deposition on boiling surface. → Amount of boron on fuel rod can be evaluated with MED model. - Abstract: In PWR primary coolant, it has been assumed that Li and B ions deposited on fuel rod surface under sub-cooled boiling conditions and they changed their chemical forms by chemical reaction with nickel iron oxides on the fuel surface. Accumulated boron on the fuel led to axial offset anomaly (AOA). In the present paper, the amount of boron deposited on the fuel surface was evaluated from two directions. The first calculated the amount with the extended micro-layer evaporation and dry-out (MED) model and the other estimated it from the viewpoint of reactor reactivity (neutron economy calculation). The MED model, which was developed for predicting iron crud deposition on the boiling surface of BWR fuel rods, was extended for application to metallic ion deposition, and modified to evaluate deposition of crud and metallic ions on sub-cooled boiling surface. Processes of growth and collapse of bubbles were calculated to determine the time from bubble generation to collapse and total evaporation volume and deposition amount of boron and metallic ions and their oxides on the fuel rod surface for a bubble. Finally chemical reaction rates of boron and metallic ions were calculated in the deposits. From the evaluation, it was concluded that: (i) the calculated deposition amount of boron on the fuel rod surface, which was four or forty times larger than measured amounts of boron and nickel oxides compounds, was seldom measured in the fuel deposits due to its high release rate; (ii) its hideout return during the reactor shutdown period was seldom observed due to its high concentration in the primary coolant

  11. Large-eddy simulation of open channel flow with surface cooling

    International Nuclear Information System (INIS)

    Walker, R.; Tejada-Martínez, A.E.; Martinat, G.; Grosch, C.E.

    2014-01-01

    Highlights: • Open channel flow comparable to a shallow tidal ocean flow is simulated using LES. • Unstable stratification is imposed by a constant surface cooling flux. • Full-depth, convection-driven, rotating supercells develop when cooling is applied. • Strengthening of cells occurs corresponding to an increasing of the Rayleigh number. - Abstract: Results are presented from large-eddy simulations of an unstably stratified open channel flow, driven by a uniform pressure gradient and with zero surface shear stress and a no-slip lower boundary. The unstable stratification is applied by a constant cooling flux at the surface and an adiabatic bottom wall, with a constant source term present to ensure the temperature reaches a statistically steady state. The structure of the turbulence and the turbulence statistics are analyzed with respect to the Rayleigh number (Ra τ ) representative of the surface buoyancy relative to shear. The impact of the surface cooling-induced buoyancy on mean and root mean square of velocity and temperature, budgets of turbulent kinetic energy (and components), Reynolds shear stress and vertical turbulent heat flux will be investigated. Additionally, colormaps of velocity fluctuations will aid the visualization of turbulent structures on both vertical and horizontal planes in the flow. Under neutrally stratified conditions the flow is characterized by weak, full-depth, streamwise cells similar to but less coherent than Couette cells in plane Couette flow. Increased Ra τ and thus increased buoyancy effects due to surface cooling lead to full-depth convection cells of significantly greater spanwise size and coherence, thus termed convective supercells. Full-depth convective cell structures of this magnitude are seen for the first time in this open channel domain, and may have important implications for turbulence analysis in a comparable tidally-driven ocean boundary layer. As such, these results motivate further study of the

  12. Tolerance of brown bear spermatozoa to conditions of pre-freezing cooling rate and equilibration time.

    Science.gov (United States)

    López-Urueña, E; Alvarez, M; Gomes-Alves, S; Martínez-Rodríguez, C; Borragan, S; Anel-López, L; de Paz, P; Anel, L

    2014-06-01

    Specific protocols for the cryopreservation of endangered Cantabrian brown bear spermatozoa are critical to create a genetic resource bank. The aim of this study was to assess the effect of cooling rates and equilibration time before freezing on post-thawed brown bear spermatozoa quality. Electroejaculates from 11 mature bears were extended to 100 × 10(6) spermatozoa/mL in a TES-Tris-Fructose-based extender, cryopreserved following performance of the respective cooling/equilibration protocol each sample was assigned to, and stored at -196 °C for further assessment. Before freezing, after thawing, and after 1 hour's incubation post-thawing at 37 °C (thermal stress test), the quality of the samples was assessed for motility by computer-assisted semen analysis, and for viability (SYBR-14/propidium iodide), acrosomal status (peanut agglutinin-fluorescein isothiocyanate /propidium iodide), and sperm chromatin stability (SCSA) by flow cytometry. In experiment 1, three cooling rates (0.25 °C/min, 1 °C/min, and 4 °C/min) to 5 °C were assessed. After thawing, total motility (%TM) was higher and percentage of damaged acrosomes (%dACR) was lower (P bear sperm. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Influence of cooling rate and antimony addition content on graphite morphology and mechanical properties of a ductile iron

    Directory of Open Access Journals (Sweden)

    Liu Zhe

    2012-05-01

    Full Text Available Cooling rate and inoculation practice can greatly affect the graphite morphology of ductile irons. In the present research, the effects of the cooling rate and antimony addition on the graphite morphology and mechanical properties of ductile irons have been studied. Three ductile iron castings were prepared through solidification under cooling conditions S (slow, M (medium and F (fast. The cooling rates around the equilibrium eutectic temperature (1,150 ℃ for these cooling conditions (S, M and F were set at 0.21 ℃·min-1, 0.32 ℃·min-1 and 0.37 ℃·min-1, respectively. In addition, four ductile iron castings were prepared by adding 0.01%, 0.02%, 0.03% and 0.04% (by weight antimony, respectively under the slow cooling condition. The results show that the nodularity index, tensile strength and hardness of the ductile iron castings without antimony addition are all improved with the increase of cooling rate, while the ductile iron casting solidified under the medium cooling rate possesses the largest number of graphite nodules. Furthermore, for the four antimony containing castings, the graphite morphology and tensile strength are also improved by the antimony additions, and the effect of antimony addition is intensified when the addition increases from 0.01% to 0.03%. Moreover, the rare earth elements (REE/antimony ratio of 2 appears to be the most effective for fine nodular graphite formation in ductile iron.

  14. Evaluating Cool Impervious Surfaces: Application to an Energy-Efficient Residential Roof and to City Pavements

    Science.gov (United States)

    Rosado, Pablo Javier

    Summer urban heat island (UHI) refers to the phenomenon of having higher urban temperatures compared to the those in surrounding suburban and rural areas. Higher urban air temperatures lead to increased cooling demand, accelerates the formation of smog, and contributes to the generation of greenhouse gas emissions. Dark-colored impervious surfaces cover a significant fraction of an urban fabric, and as hot and dry surfaces, are a major contributor to the UHI effect. Adopting solar-reflective ("cool") roofs and cool pavements, and increasing the urban vegetation, are strategies proven to mitigate urban heat islands. These strategies often have an "indirect" effect (ambient cooling) and "direct" effect (change in solar energy flux entering the conditioned space) on the energy use of buildings. This work investigates some elements of the UHI mitigation strategies, specifically the annual direct effect of a cool roof, and the direct and indirect effects of cool pavements. The first topic researched in this paper consists in an experimental assessment of the direct effects from replacing a conventional dark roof with a highly energy-efficient cool roof. The study measures and calculates the annual benefits of the cool roof on the cooling and heating energy uses, and the associated emission reductions. The energy savings attributed to the cool roof are validated by measuring the difference between the homes in the heat loads that entered the conditioned space through the ceiling and HVAC ducts. Fractional annual cooling energy savings (26%) were 2.6 times the 10% daily cooling energy savings measured in a previous study that used a white coating to increase the albedo of an asphalt shingle roof by the same amount (0.44). The improved cooling energy savings (26% vs. 10%) may be attributed to the cool tile's above-sheathing ventilation, rather than to its high thermal mass. The roof also provided energy savings during the heating season, yielding fractional annual gas

  15. Cooling curve analysis in binary Al-Cu alloys: Part II- Effect of Cooling Rate and Grain Refinement on The Thermal and Thermodynamic Characteristics

    Directory of Open Access Journals (Sweden)

    Mehdi Dehnavi

    2015-09-01

    Full Text Available The Al-Cu alloys have been widely used in aerospace, automobile, and airplane applications. Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys for grain refinement. The cooling curve analysis (CCA has been used extensively in metal casting industry to predict microstructure constituents, grain refinement and to calculate the latent heat of solidification. The aim of this study is to investigate the effect of cooling rate and grain refinement on the thermal and thermodynamic characteristics of Al-Cu alloys by cooling curve analysis. To do this, Al-Cu alloys containing 3.7, and 4.8 wt.% Cu were melted and solidified with 0.04, 0.19, 0.42, and 1.08 K/s cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. Some samples were Grain refined by Al-5Ti-1B to see the effect of grain refinement on the aforementioned properties. The results show that, in a well refined alloy, nucleation will occur in a shorter time, and a undercooling approximately decreases to zero. The other results show that, with considering the cooling rate being around 0.1 °C/s, the Newtonian method is efficient in calculating the latent heat of solidification.

  16. Effectiveness of Ti-micro alloying in relation to cooling rate on corrosion of AZ91 Mg alloy

    International Nuclear Information System (INIS)

    Candan, S.; Celik, M.; Candan, E.

    2016-01-01

    In this study, micro Ti-alloyed AZ91 Mg alloys (AZ91 + 0.5wt.%Ti) have been investigated in order to clarify effectiveness of micro alloying and/or cooling rate on their corrosion properties. Molten alloys were solidified under various cooling rates by using four stage step mold. The microstructural investigations were carried out by using scanning electron microscopy (SEM). Corrosion behaviors of the alloys were evaluated by means of immersion and electrochemical polarization tests in 3.5% NaCl solution. Results showed that the Mg 17 Al 12 (β) intermetallic phase in the microstructure of AZ91 Mg alloy formed as a net-like structure. The Ti addition has reduced the distribution and continuity of β intermetallic phase and its morphology has emerged as fully divorced eutectic. Compared to AZ91 alloy, the effect of the cooling rate in Ti-added alloy on the grain size was less pronounced. When AZ91 and its Ti-added alloys were compared under the same cooling conditions, the Ti addition showed notably high corrosion resistance. Electrochemical test results showed that while I corr values of AZ91 decrease with the increase in the cooling rate, the effect of the cooling rate on I corr values was much lower in the Ti-added alloy. The corrosion resistance of AZ91 Mg alloy was sensitive towards the cooling rates while Ti-added alloy was not affected much from the cooling conditions. - Highlights: • Effect the cooling rate on grain size was less pronounced in the Ti-added alloy. • The morphology of the β phase transformed into fully divorced eutectics. • Ti addition exhibited significantly higher corrosion resistance. • Ti micro alloying is more effective than faster cooling of the alloy on corrosion.

  17. Heating and cooling rates and their etTects upon heart rate in the ...

    African Journals Online (AJOL)

    1988-03-16

    Mar 16, 1988 ... Many studies have demonstrated that several reptile species have the ability to physiologically alter their rates of heat exchange. Studies of lizards have ..... are low. The shell is also an effective insulator (Mackay. 1964; McGinnis & Voigt 1971) and acts as a shield against heat loss when all the limbs are ...

  18. Ice growth and interface oscillation of water droplets impinged on a cooling surface

    Science.gov (United States)

    Hagiwara, Yoshimichi; Ishikawa, Shoji; Kimura, Ryota; Toyohara, Kazumasa

    2017-06-01

    We focused on the attenuation of air-water interface oscillation for impinged water droplets freezing on a cooling surface. We carried out not only experiments but also two-dimensional numerical simulation on the droplets using a Phase-field method and an immersed boundary method. The Reynolds number and Weber number were in the range of 35-129 and 1.6-22, respectively. The experimental and computational results showed that the height of the impinged droplets on the symmetrical axis started to oscillate as a result of the impact of the collision of droplets with the surfaces in all the cases that we investigated. The measured frequency of the oscillations in the case of the adiabatic droplets was equal to the frequency estimated from the equation for the capillary-gravity waves on sessile droplets (Temperton, 2013) [30]. The oscillations converged rapidly in all impinged water droplets that froze on the cooling surface. This is due partly to the growth of ice shells along the air-water interface and partly to decreases in water volume as a result of the ice growth mainly on the cooling surface. In addition, the thermal field was disturbed not only by the latent heat transfer but also by the upward component of recirculating flow induced by the droplet impingement.

  19. Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

    Directory of Open Access Journals (Sweden)

    Abbas Monzavi

    2014-04-01

    Full Text Available Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage.The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems.Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture.In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (P<0.001.Based on the results, no thermal damage was observed during implant surface decontamination by Er:YAG laser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

  20. Cooling rate of chondrules in ordinary chondrites revisited by a new geospeedometer based on the compensation rule

    Science.gov (United States)

    Béjina, Frédéric; Sautter, Violaine; Jaoul, Olivier

    2009-01-01

    For several decades efforts to constrain chondrite cooling rates from diffusion zoning in olivine gave rise to a range of values from 5 to 8400 K/h (Desch, S.J., Connolly Jr., H.C., 2002. A model for the thermal processing of particles in solar nebula shocks: application to cooling rates of chondrules. Meteorit. Planet. Sci. 37, 183-208; Greeney, S., Ruzicka, A., 2004. Relict forsterite in chondrules: implications for cooling rates. Lunar Planet. Sci. XXXV, abstract # 1246.). Such large uncertainties directly reflect the variability of diffusion data. Alternatively, from this variability results a compensation rule, log D0 = a + bE (diffusion coefficients are written D = D0 exp(- E/ RT)). We test a new geospeemetry approach, based on this rule, on cooling of chondrules in chondrites, Sahara-97210 LL 3.2 and Wells LL 3.3. Greeney and Ruzicka (2004) matched Fe-Mg diffusion profiles in olivine from these chondrites with cooling rates between 200 and 6000 K/h. In our geospeedometry model, the use of the compensation rule greatly reduces the uncertainties by avoiding the choice of one diffusion coefficient among many. The cooling rates we found are between 700 and 3600 K/h for Sahara and 700-1600 K/h for Wells. Finally, we discuss the influence of our analytical model parameters on our cooling rate estimates.

  1. Active cooling-based surface confinement system for thermal soil treatment

    Science.gov (United States)

    Aines, R.D.; Newmark, R.L.

    1997-10-28

    A thermal barrier is disclosed for surface confinement with active cooling to control subsurface pressures during thermal remediation of shallow (5-20 feet) underground contaminants. If steam injection is used for underground heating, the actively cooled thermal barrier allows the steam to be injected into soil at pressures much higher (20-60 psi) than the confining strength of the soil, while preventing steam breakthrough. The rising steam is condensed to liquid water at the thermal barrier-ground surface interface. The rapid temperature drop forced by the thermal barrier drops the subsurface pressure to below atmospheric pressure. The steam and contaminant vapors are contained by the thermal blanket, which can be made of a variety of materials such as steel plates, concrete slabs, membranes, fabric bags, or rubber bladders. 1 fig.

  2. Numerical Modeling of Surface and Volumetric Cooling using Optimal T- and Y-shaped Flow Channels

    Science.gov (United States)

    Kosaraju, Srinivas

    2017-11-01

    The layout of T- and V-shaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, air conditioning and electronics cooling. In this paper, an effort has been made to study the heat transfer characteristics of multiple T- and Y-shaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Comparisons are made with similar results published in literature.

  3. Performance enhancement of sub-nanosecond diode-pumped passively Q-switched Yb:YAG microchip laser with diamond surface cooling.

    Science.gov (United States)

    Zhuang, W Z; Chen, Yi-Fan; Su, K W; Huang, K F; Chen, Y F

    2012-09-24

    We experimentally confirm that diamond surface cooling can significantly enhance the output performance of a sub-nanosecond diode-end-pumped passively Q-switched Yb:YAG laser. It is found that the pulse energy obtained with diamond cooling is approximately 1.5 times greater than that obtained without diamond cooling, where a Cr(4+):YAG absorber with the initial transmission of 84% is employed. Furthermore, the standard deviation of the pulse amplitude peak-to-peak fluctuation is found to be approximately 3 times lower than that measured without diamond cooling. Under a pump power of 3.9 W, the passively Q-switched Yb:YAG laser can generate a pulse train of 3.3 kHz repetition rate with a pulse energy of 287 μJ and with a pulse width of 650 ps.

  4. Survival of mouse embryos after vitrification depending on the cooling rate of the cryoprotectant solution.

    Science.gov (United States)

    Hredzák, R; Ostró, A; Zdilová, Viera; Maracek, I; Kacmárik, J

    2006-03-01

    The aim of the study was to determine the relationship between the rate of cooling of eight-cell mouse embryos to the temperature of liquid nitrogen (-196 degrees C) and their developmental capacity after thawing on the basis of their ability to leave the zona pellucida ('hatching') during in vitro culturing. Eight-cell embryos were obtained from superovulated female mice and divided into three experimental and one control group. Embryos from the experimental groups were cryopreserved by the vitrification method using ethylene glycol as cryoprotectant. The vitrification protocols used in the study differed in the rate of cooling of the cryoprotectant solution. Embryos from the first group were frozen in conventional 0.25-ml plastic straws, those from the second group in pipetting 'tips', and embryos from the third group, placed in vitrification solution, were introduced dropwise directly into liquid nitrogen. The control group of embryos was cultured in vitro without freezing in a culturing medium in an environment consisting of 95% air and 5% CO2. The developmental capacity of thawed embryos was assessed on the basis of their ability to leave the zona pellucida ('hatching') after three days of in vitro culturing. In the control group 95.1% of embryos 'hatched'. A significantly higher number of embryos that 'hatched' after thawing was observed in the group introduced dropwise directly into liquid nitrogen (60.0%) compared to the group frozen in pipetting 'tips' (37.9%). The group frozen in straws yielded significantly the lowest proportion of 'hatching' embryos (8.1%). These results showed that increasing cooling rates during vitrification of embryos improved their survival.

  5. Effects of the cooling rate on the shear behavior of continuous glass fiber/impact polypropylene composites (GF-IPP)

    KAUST Repository

    Wafai, Husam

    2016-09-20

    Fiber-reinforced composites with improved dissipation of energy during impact loading have recently been developed based on a polypropylene copolymer commonly called impact polypropylene (IPP). Composites made of IPP reinforced with glass fibers (GF) are particularly attractive to the automotive industry due to their low cost and good impact resistance. In such composites, the cooling rate varies depending on processing techniques and manufacturing choices. Here, we study the effects of the cooling rate of GF-IPP composites on shear behavior, which is critical in impact applications, using [±45]s monotonic and cyclic (load/unload) tensile specimens. The specimens were manufactured under a wide range of cooling rates (3 °C/min, 22 °C/min, 500–1000 °C/min). Mainly dominated by the properties of the matrix, the global shear behavior of GF-IPP composites differed considerably with respect to the cooling rate. However, the performance of the fiber-matrix interface (chemically modified) appeared to be unaffected by the range of cooling rates used in this study. We found that the cooling rate has a minor effect on the rate of damage accumulation, while it strongly modifies the shear-activated rate-dependant viscoelastic behavior. © 2016 Elsevier Ltd

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

    Directory of Open Access Journals (Sweden)

    P. A. Alpert

    2016-02-01

    Full Text Available 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

  7. Effect of shocks on film cooling of a full scale turbojet exhaust nozzle having an external expansion surface

    Science.gov (United States)

    Straight, D. M.

    1979-01-01

    Cooling is one of the critical technologies for efficient design of exhaust nozzles, especially for the developing technology of nonaxisymmetric (2D) nozzles for future aircraft applications. Several promising 2D nozzle designs have external expansion surfaces which need to be cooled. Engine data are scarce, however, on nozzle cooling effectiveness in the supersonic flow environment (with shocks) that exists along external expansion surfaces. This paper will present experimental film cooling data obtained during exploratory testing with an axisymmetric plug nozzle having external expansion and installed on an afterburning turbojet engine in an altitude test facility. The data obtained shows that the shocks and local hot gas stream conditions have a marked effect on film cooling effectiveness. An existing film cooling correlation is adequate at some operating conditions but inadequate at other conditions such as in separated flow regions resulting from shock-boundary-layer interactions.

  8. Recent global-warming hiatus tied to equatorial Pacific surface cooling.

    Science.gov (United States)

    Kosaka, Yu; Xie, Shang-Ping

    2013-09-19

    Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.

  9. Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

    Science.gov (United States)

    Monzavi, Abbas; Shahabi, Sima; Fekrazad, Reza; Behruzi, Roohollah; Chiniforush, Nasim

    2014-03-01

    Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage. The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems. Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture. In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (Plaser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

  10. Distinct global warming rates tied to multiple ocean surface temperature changes

    Science.gov (United States)

    Yao, Shuai-Lei; Luo, Jing-Jia; Huang, Gang; Wang, Pengfei

    2017-07-01

    The globally averaged surface temperature has shown distinct multi-decadal fluctuations since 1900, characterized by two weak slowdowns in the mid-twentieth century and early twenty-first century and two strong accelerations in the early and late twentieth century. While the recent global warming (GW) hiatus has been particularly ascribed to the eastern Pacific cooling, causes of the cooling in the mid-twentieth century and distinct intensity differences between the slowdowns and accelerations remain unclear. Here, our model experiments with multiple ocean sea surface temperature (SST) forcing reveal that, although the Pacific SSTs play essential roles in the GW rates, SST changes in other basins also exert vital influences. The mid-twentieth-century cooling results from the SST cooling in the tropical Pacific and Atlantic, which is partly offset by the Southern Ocean warming. During the recent hiatus, the tropical Pacific-induced strong cooling is largely compensated by warming effects of other oceans. In contrast, during the acceleration periods, ubiquitous SST warming across all the oceans acts jointly to exaggerate the GW. Multi-model simulations with separated radiative forcing suggest diverse causes of the SST changes in multiple oceans during the GW acceleration and slowdown periods. Our results highlight the importance of multiple oceans on the multi-decadal GW rates.

  11. Surface condition effects on tritium permeation through the first wall of a water-cooled ceramic breeder blanket

    International Nuclear Information System (INIS)

    Zhou, H.-S.; Xu, Y.-P.; Liu, H.-D.; Liu, F.; Li, X.-C.; Zhao, M.-Z.; Qi, Q.; Ding, F.; Luo, G.-N.

    2016-01-01

    Highlights: • We investigate surface effects on T transport through the first wall. • We solve transport equations with various surface conditions. • The RAFMs walls w/and w/o W exhibit different T permeation behavior. • Diffusion in W has been found to be the rate-limiting step. - Abstract: Plasma-driven permeation of tritium (T) through the first wall of a water-cooled ceramic breeder (WCCB) blanket may raise safety and other issues. In the present work, surface effects on T transport through the first wall of a WCCB blanket have been investigated by theoretical calculation. Two types of wall structures, i.e., reduced activation ferritic/martensitic steels (RAFMs) walls with and without tungsten (W) armor, have been analyzed. Surface recombination is assumed to be the boundary condition for both the plasma-facing side and the coolant side. It has been found that surface conditions at both sides can affect T permeation flux and inventory. For the first wall using W as armor material, T permeation is not sensitive to the plasma-facing surface conditions. Contamination of the surfaces will lead to higher T inventory inside the first wall.

  12. Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies AO2, AO3 and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters AO3

    Science.gov (United States)

    White, Raymond E., III

    1998-01-01

    This final report uses ROSAT observations to analyze two different studies. These studies are: Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies; and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters.

  13. Determination of critical cooling rates in metallic glass forming alloy libraries through laser spike annealing.

    Science.gov (United States)

    Bordeenithikasem, Punnathat; Liu, Jingbei; Kube, Sebastian A; Li, Yanglin; Ma, Tianxing; Scanley, B Ellen; Broadbridge, Christine C; Vlassak, Joost J; Singer, Jonathan P; Schroers, Jan

    2017-08-02

    The glass forming ability (GFA) of metallic glasses (MGs) is quantified by the critical cooling rate (R C ). Despite its key role in MG research, experimental challenges have limited measured R C to a minute fraction of known glass formers. We present a combinatorial approach to directly measure R C for large compositional ranges. This is realized through the use of compositionally-graded alloy libraries, which were photo-thermally heated by scanning laser spike annealing of an absorbing layer, then melted and cooled at various rates. Coupled with X-ray diffraction mapping, GFA is determined from direct R C measurements. We exemplify this technique for the Au-Cu-Si system, where we identify Au 56 Cu 27 Si 17 as the alloy with the highest GFA. In general, this method enables measurements of R C over large compositional areas, which is powerful for materials discovery and, when correlating with chemistry and other properties, for a deeper understanding of MG formation.

  14. Influence of different cooling rates on the microstructure of the HAZ and welding CCT diagram of CLAM steel

    International Nuclear Information System (INIS)

    Zheng Shuhui; Wu Qingsheng; Huang Qunying; Liu Shaojun; Han Yangyang

    2011-01-01

    The evolution of microstructure in the weld HAZ (Heat Affected Zone) under welding thermal cycle was simulated by Gleeble-1500. The microstructures and properties of HAZ at different cooling rates were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and microhardness test. The results showed that when the cooling rates ranged from 3600 K/min to 60 K/min, fully martensitic transformations were achieved, and the cooling rates had little influence on the microstructure and microhardness of martensite. The maximum cooling rate to form ferrite was 60 K/min. When the cooling rates ranged from 60 K/min to 1 K/min, the microhardness of the HAZ began to decrease due to the presence of ferrite, and the lath sizes grew up to 0.13-0.15 μm. The critical cooling rate to gain fully ferrite was found to be slower than 1 K/min. The welding CCT diagram of CLAM steel was constructed and it showed that there were ferrite and martensite transformation regions only. The diagram made it possible to predict the microstructures and properties of HAZ and became an important tool to evaluate weldability of CLAM steel.

  15. Effect of Cooling Rate on Morphology of TiAl3 Particles in Al–4Ti Master Alloy

    Directory of Open Access Journals (Sweden)

    Jianhua Zhao

    2017-02-01

    Full Text Available The Al–4Ti master alloy was fabricated by aluminum (Al and sponge titanium particle in a resistance furnace at different cooling rates. This work aims to investigate the relationship between the cooling rate and morphology of TiAl3. The microstructure and composition of master alloys at different cooling rates were characterized and analyzed by optical microscopy (OM, X-ray diffraction (XRD, differential scanning calorimetry (DSC, and SEM with energy dispersive spectroscopy (EDS. The results showed that various morphologies of TiAl3 particles in the Al–4Ti master alloy could be acquired at different cooling rates. Petal-like, blocky, and flake-like TiAl3 particles in the Al–4Ti master alloy were respectively acquired at the cooling rates of 3.36 K/s, 2.57 K/s, and 0.31 K/s. It was also found that the morphology of TiAl3 particles in the prepared master alloy changed from petal-like to blocky, then finally to flake-like, with the decrease of cooling rate. In addition, the morphology of the TiAl3 particles has no effect on the phase inversion temperature of Al–4Ti master alloy.

  16. Drivers of Antarctic sea-ice expansion and Southern Ocean surface cooling over the past four decades

    Science.gov (United States)

    Purich, Ariaan; England, Matthew

    2017-04-01

    Despite global warming, total Antarctic sea-ice coverage has increased overall during the past four decades. In contrast, the majority of CMIP5 models simulate a decline. In addition, Southern Ocean surface waters have largely cooled, in stark contrast to almost all historical CMIP5 simulations. Subantarctic Surface Waters have cooled and freshened while waters to the north of the Antarctic Circumpolar Current have warmed and increased in salinity. It remains unclear as to what extent the cooling and Antarctic sea-ice expansion is due to natural variability versus anthropogenic forcing; due for example to changes in the Southern Annular Mode (SAM). It is also unclear what the respective role of surface buoyancy fluxes is compared to internal ocean circulation changes, and what the implications are for longer-term climate change in the region. In this presentation we will outline three distinct drivers of recent Southern Ocean surface trends that have each made a significant contribution to regional cooling: (1) wind-driven surface cooling and sea-ice expansion due to shifted westerly winds, (2) teleconnections of decadal variability from the tropical Pacific, and (3) surface cooling and ice expansion due to large-scale Southern Ocean freshening, most likely driven by SAM-related precipitation trends over the open ocean. We will also outline the main reasons why climate models for the most part miss these Southern Ocean cooling trends, despite capturing overall trends in the SAM.

  17. Surface Thermal Insulation and Pipe Cooling of Spillways during Concrete Construction Period

    Directory of Open Access Journals (Sweden)

    Wang Zhenhong

    2014-01-01

    Full Text Available Given that spillways adopt a hydraulic thin concrete plate structure, this structure is difficult to protect from cracks. The mechanism of the cracks in spillways shows that temperature stress is the major reason for cracks. Therefore, an effective way of preventing cracks is a timely and reasonable temperature-control program. Studies show that one effective prevention method is surface thermal insulation combined with internal pipe cooling. The major factors influencing temperature control effects are the time of performing thermal insulation and the ways of internal pipe cooling. To solve this problem, a spillway is taken as an example and a three-dimensional finite element program and pipe cooling calculation method are adopted to conduct simulation calculation and analysis on the temperature fields and stress fields of concretes subject to different temperature-control programs. The temperature-control effects are then compared. Optimization results show that timely and reasonable surface thermal insulation and water-flowing mode can ensure good temperature-control and anticrack effects. The method has reference value for similar projects.

  18. The rate of diffusion into advanced gas cooled reactor moderator bricks: an equivalent cylinder model

    International Nuclear Information System (INIS)

    Kyte, W.S.

    1980-01-01

    The graphite moderator bricks which make up the moderator of an advanced gas-cooled nuclear reactor (AGR) are of many different and complex shapes. Many physico-chemical processes that occur within these porous bricks include a diffusional step and thus to model these processes it is necessary to solve the diffusion equation (with chemical reaction) in a porous medium of complex shape. A finite element technique is applied to calculating the rate at which nitrogen diffuses into and out of the porous moderator graphite during operation of a shutdown procedure for an AGR. However, the finite element method suffers from several disadvantages that undermine its general usefulness for calculating rates of diffusion in AGR moderator cores. A model which overcomes some of these disadvantages is presented (the equivalent cylinder model) and it is shown that this gives good results for a variety of different boundary and initial conditions

  19. Rotational Laser Cooling of MgH+ Ions and Rotational Rate Measurements

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Staanum, Peter; Højbjerre, Klaus

    A method of laser cooling vibrationally and translationally cold trapped MgH+ ions to the rotational ground state using optical pumping was recently demonstrated in our group [1]. This method relies on the 293 K blackbody radiation to redistribute population among the rotational states, while...... exciting a single rovibrational transition within the X1Σ+ electronic ground state for optical pumping into the rovibrational ground state. To model the expected rotational state distributions after the application of the laser beam, one has to know the various rotational transitions rates in the present...... blackbody radiation field. To undertake such modelling, we will carry out measurements of a series of transition rates between rotational states in the vibronic ground state at room temperature. The measurements will be performed by the same Resonance Enhanced Multi-Photon Dissociation (REMPD) process used...

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

    Science.gov (United States)

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

    1989-09-01

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

  1. Heat Transfer and Observation of Droplet-Surface Interactions During Air-Mist Cooling at CSP Secondary System Temperatures

    Science.gov (United States)

    Huerta L., Mario E.; Mejía G., M. Esther; Castillejos E., A. Humberto

    2016-04-01

    Air-mists are key elements in the secondary cooling of modern thin steel slab continuous casters. The selection of water, W, and air, A, flow rates, and pressures in pneumatic nozzles open up a wide spectrum of cooling possibilities by their influence on droplet diameter, d, droplet velocity, v, and water impact flux, w. Nonetheless, due to the harsh environment resulting from the high temperatures and dense mists involved, there is very little information about the correlation between heat flux extracted, - q, and mist characteristics, and none about the dynamics of drop-wall interactions. For obtaining both kinds of information, this work combines a steady-state heat flux measuring method with a visualization technique based on a high-speed camera and a laser illumination system. For wall temperatures, T w, between ~723 K and ~1453 K (~450 °C and ~1180 °C), which correspond to film boiling regime, it was confirmed that - q increases with increase in v, w, and T w and with decrease in d. It should be noticed, however, that the increase in w generally decreases the spray cooling effectiveness because striking drops do not evaporate efficiently due to the interference by liquid remains from previous drops. Visualization of the events happening close to the surface also reveals that the contact time of the liquid with the surface is very brief and that rebounding, splashing, sliding, and levitation of drops lead to ineffective contact with the surface. At the center of the mist footprint, where drops impinge nearly normal to the surface those with enough momentum establish intimate contact with it before forming a vapor layer that pushes away the remaining liquid. Also, some drops are observed sliding upon the surface or levitating close to it; these are drops with low momentum which are influenced by the deflecting air stream. At footprint positions where oblique impingement occurs, frequently drops are spotted sliding or levitating and liquid films flowing in

  2. Evaporation rate calculation of the RSG-GAS reactor cooling pool water

    International Nuclear Information System (INIS)

    Dibyo, Sukmanto

    2002-01-01

    Evaporation rate is necessary to be known because it is closely related to humidity control and make-up of pool water. This paper calculates the evaporation rate from the reactor pool to the operation hall of the RSG-GAS. The evaporation rate was calculated based on temperature, pressure, mass-transfer coefficient and other complement data. Calculation result indicates that the reactor pool temperature has a great influence to the evaporation rate. Whereas air temperature given very small effect to the evaporation. Based on the collecting data and warm water layer temperature of 46 oC , the evaporation rate was found to be 8 kg/hr. This evaporation causes gradually humidity increase at the operation hall if temperature of ventilation cooling system is mostly higher than its dew point. As the consequence of evaporation, the decrease of pool water level is relatively small even without the pool make-up system operation. The minimum level of pool water will be reached after 46 days

  3. Post-cooling survival, growth and deformity rates in zebrafish embryos (Danio rerio).

    Science.gov (United States)

    do Carmo Faria Paes, Maria; Satiko Okada Nakaghi, Laura

    2018-02-01

    This study investigated and analysed survival, growth and macro- and microscopic damage during the development of zebrafish embryos up to the adult stage after undergoing cooling. The embryos at 50% epiboly stage were selected, submerged in cryoprotectant solution of methanol and sucrose, cooled gradually to 0 ± 2°C temperature, and divided into two groups with different storage times (6 and 18 h). Subsequently, the embryos were reheated, rehydrated and incubated normally. The experiment lasted 5 months and, from hatching onward, the larvae were examined, collected and processed at pre-established time intervals. The hatching rate was significantly higher for the larvae stored for 18 h compared with the 6-h group. However, embryos from this group gave rise to a larger number of malformations, and these were much more severe compared with those in the 6 h group, which led to a higher mortality in the long term. Regarding larval length, the animals of the 6 h group had higher mean total length compared with the 18 h group, but both treatments were inferior to the control. Numerous macro- and microscopic malformations were observed and, in both treatments, only the morphologically normal individuals were able to develop to the adult stage, with organ development similar to the control, except for the gonads that were still undifferentiated in treated animals.

  4. Influence of cooling rate on y'morphology in cast Ni – base superalloy

    Directory of Open Access Journals (Sweden)

    J. Belan

    2009-04-01

    Full Text Available The Ni – base superalloys, which are combined an unique physical and mechanical properties, are used in aircraft industry for productionof aero engine most stressed parts, as are turbine blades. From this reason a dendrite arm spacing, carbides size and distribution, morphology,number and value of y'- phase are very important structural characteristics for blade lifetime prediction as well as aero engine its self. In this article are used methods of quantitative metallography (software LUCIA for carbides evaluation, measuring of secondary dendrite arm spacing and coherent testing grid for y' - phase evaluation for evaluation of structural characteristics mentioned above on experimental material – Ni base superalloy ŽS6K. The high temperature effect represented here by heat treatment at 800°C followed with holding time about 10 hours, and cooling rate, here represented by three various cooling mediums as water, air, and oil, on structural characteristics and application of quantitative methods evaluation are presented in this paper.

  5. Effect of cooling rate and forced convection on as-cast structure of 2205 duplex stainless steel

    Directory of Open Access Journals (Sweden)

    Cheng Zhang

    2015-01-01

    Full Text Available To forecast the as-cast structure and ferrite-austenite phase ratio of 2205 duplex stainless steel (DSS, the effects of cooling rate and forced convection were observed in a high-vacuum resistance furnace in which the forced convection was created by the rotation of the crucible. The as-cast structure of all 2205 DSS samples is full equiaxed grains, and the microstructure consists of a great amount of desirable intra-granular austenite inside the continuous ferrite grain matrix, besides Widmanstatten austenite and grain boundary austenite. The ferrite grain size decreases gradually with the increase in the cooling rates (20 to 60 ìC·min-1 or the forced convection, while the ferrite grains of the samples solidified with a strong convection are barely changed when the cooling rate is below 50 ìC·min-1. Moreover, a small grain size is beneficial for the austenite formation but the influence is not very obvious under the cooling rates in the range of 5 to 50 ìC·min-1. Compared with grain size, the cooling rate has a greater influence on the final ferrite content. A model based on the experimental results is established to predict the ferrite content, which could be approximated by ヤ(%=20.5·exp(c/80.0+0.34d+34.1, where c is the cooling rate in ìC·min-1 and d is the grain size in mm. By using this model, the dependence of the final ferrite content on cooling rate and grain size is well described.

  6. Combined effects of cerium and cooling rate on microstructure and mechanical properties of AZ91 magnesium alloy

    Science.gov (United States)

    Cai, Huisheng; Guo, Feng; Su, Juan

    2018-01-01

    The specimens of AZ91–xCe(x = 0, 0.3, 0.6, 0.9, 1.2, mass fraction wt%) with different thicknesses were prepared by die casting process, their as-cast microstructure and room temperature mechanical properties were investigated to analyze the change rule of microstructure and mechanical properties of AZ91 magnesium alloy under combined effects of cooling rate and cerium content. The results show that, the microstructure and mechanical properties of AZ91 magnesium alloy were twofold influenced by cooling rate and cerium content. With the increase of cooling rate and Ce content, the average as-cast grain size is evidently refined; the amount of β-Mg17Al12 decreases and distribution becomes discrete. While decreasing cooling rate or increasing Ce content, Al4Ce phase is more and the morphology tends to strip and needle from granular and short rod-like. The tensile strength and elongation of AZ91–xCe magnesium alloy are improved with increasing cooling rate. With the increase of Ce content, the tensile strength and elongation of AZ91–xCe magnesium alloy increased first and decreased afterwards, besides the action of Ce to improve tensile strength and elongation is more evident under faster cooling rate. Mechanical properties of samples are optimal in this work, when Ce content is 0.96% and cooling rate is 39.6 K s‑1, tensile strength (259.7 MPa) and elongation (5.5%) are reached maximum, respectively.

  7. Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands

    Science.gov (United States)

    Braun, Jean; Gemignani, Lorenzo; van der Beek, Peter

    2018-03-01

    One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo-Siang-Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo-Siang-Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i.e., from the predicted distribution of surface ages within each catchment and from the relative contribution of any given catchment to the

  8. Thermal-Hydraulic Performance of a Corrugated Cooling Fin with Louvered Surfaces

    DEFF Research Database (Denmark)

    Sønderby, Simon Kaltoft; Hosseini, Seyed Mojtaba Mir; Rezaniakolaei, Alireza

    2017-01-01

    The main objective of the article is to investigate thermal-hydraulic performance of a corrugated cooling fin with louvered surfaces. The investigation is carried out using the fin geometry of one most commonly used liquid-to-air heat exchangers. The investigation was carried out by numerically s...... between -45.5 % to 86.4 % were reported for the f-factor. The thermal part of the model was validated with good confidence, while the frictional part of the model was validated with a smaller degree of certainty....

  9. Cooling Rates of Mantle Peridotites Estimated from Lithophile Trace Element Diffusion in Orthopyroxene

    Science.gov (United States)

    von der Handt, A.; Hellebrand, E.; Snow, J. E.

    2007-12-01

    Cooling rates of ocean floor mantle rocks from mid-ocean ridges can potentially provide important information about ridge dynamics, emplacement mechanisms and mantle uplift. There are a growing number of geospeedometric methods to retrieve such cooling rates in various settings. However, few exist for typical four- phase mantle peridotites and they only cover temperatures below 800° C. The down-temperature lithophile trace element exchange between clinopyroxene (cpx) and orthopyroxene (opx) can provide such a high- temperature spinel peridotite geospeedometer. Orthopyroxenes studied by SIMS from two fresh Gakkel Ridge peridotites are zoned in all trace elements while clinopyroxenes are homogeneous. This allows the calculation of equilibrium temperatures [1]. Several profiles in opx cover a range of 1250° C (opx core) to 800° C (opx rim) and are in agreement with straightforward diffusion and closure temperature models. The systematics of REE diffusion in opx deviate from the results of a recent experimental study [2]. The data allow us to estimate diffusion systematics of 16 elements (REE and TE) and their cation distributions in orthopyroxene. The data set is internally coherent as all elements were subjected to the same extrinsic parameters. 1. Decreasing ionic radius increases REE diffusion in opx (as it does in cpx). 2. M2-site diffusion is controlled more by ionic radius than by cationic charge. 3. M1-site diffusion is controlled by both ionic radius and cationic charge. 4. M1-site diffusion is generally slower than M2-site diffusion for isovalent cations, most likely because of higher M1- site energies compared to M2-site. The advantages of this geospeedometer should be its relatively good precision, use of standard analytical methods and its coverage of the important range between solidus temperatures and 800° C. In combination with other geospeedometers it will be possible to retrieve the continuous cooling history of a mantle rock from its solidus down

  10. Thermal History of CBb Chondrules and Cooling Rate Distributions of Ejecta Plumes

    Science.gov (United States)

    Hewins, R. H.; Condie, C.; Morris, M.; Richardson, M. L. A.; Ouellette, N.; Metcalf, M.

    2018-03-01

    It has been proposed that some meteorites, CB and CH chondrites, contain material formed as a result of a protoplanetary collision during accretion. Their melt droplets (chondrules) and FeNi metal are proposed to have formed by evaporation and condensation in the resulting impact plume. We observe that the skeletal olivine (SO) chondrules in CBb chondrites have a blebby texture and an enrichment in refractory elements not found in normal chondrules. Because the texture requires complete melting, their maximum liquidus temperature of 1928 K represents a minimum temperature for the putative plume. Dynamic crystallization experiments show that the SO texture can be created only by brief reheating episodes during crystallization, giving a partial dissolution of olivine. The ejecta plume formed in a smoothed particle hydrodynamics simulation served as the basis for 3D modeling with the adaptive mesh refinement code FLASH4.3. Tracer particles that move with the fluid cells are used to measure the in situ cooling rates. Their cooling rates are ∼10,000 K hr‑1 briefly at peak temperature and, in the densest regions of the plume, ∼100 K hr‑1 for 1400–1600 K. A small fraction of cells is seen to be heating at any one time, with heating spikes explained by the compression of parcels of gas in a heterogeneous patchy plume. These temperature fluctuations are comparable to those required in crystallization experiments. For the first time, we find an agreement between experiments and models that supports the plume model specifically for the formation of CBb chondrules.

  11. Late Paleozoic-Middle Mesozoic uplift rate, cooling rate and geothermal gradient for south-central New York state

    International Nuclear Information System (INIS)

    Johnsson, M.J.

    1985-01-01

    Apatite and zircon crystals were recovered from the Tioga metabentonite (Middle Devonian) at Cherry Valley, New York and from a metabentonite at the top of the Black River Group (Middle Ordovician) at Middleville, New York. Fission-track ages obtained from these minerals are younger than the stratigraphic ages of the units, indicating total or partial resetting of the mineral ages due to thermal annealing of fission-tracks. The age data allow for calculation of a mean uplift rate of 0.019 +- 0.009 mm/yr for the interval 193 to 155 Myr, and a mean cooling rate of 0.38 +- 0.11 0 C/Myr for the interval 354 to 155 Myr. An average geothermal gradient for the interval 354 to 155 Myr is 20 +- 11 C/km. The partially reset zircon age from the Black River metabentonite indicates that the Middle Ordovician rocks of south-central New York have been exposed to temperatures approaching approx. 175 C. This temperature, in conjunction with the calculated geothermal gradient, implies burial of these units to depths approaching 8 km. Such burial suggests that extensive Carboniferous sediments once covered southern New York, and that the Alleghenian Orogeny had a stronger sedimentalogical influence in the northern portion of the Appalachian Basin than has been previously recognized. (author)

  12. Advanced Liquid Cooling for a Traction Drive Inverter Using Jet Impingement and Microfinned Enhanced Surfaces: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Waye, S. K.; Narumanchi, S.; Mihalic, M.; Moreno, G.; Bennion, K.; Jeffers, J.

    2014-08-01

    Jet impingement on plain and micro-finned enhanced surfaces was compared to a traditional channel flow configuration. The jets provide localized cooling to areas heated by the insulated-gate bipolar transistor and diode devices. Enhanced microfinned surfaces increase surface area and thermal performance. Using lighter materials and designing the fluid path to manage pressure losses increases overall performance while reducing weight, volume, and cost. Powering four diodes in the center power module of the inverter and computational fluid dynamics (CFD) modeling was used to characterize the baseline as well as jet-impingement-based heat exchangers. CFD modeling showed the thermal performance improvements should hold for a fully powered inverter. Increased thermal performance was observed for the jet-impingement configurations when tested at full inverter power (40 to 100 kW output power) on a dynamometer. The reliability of the jets and enhanced surfaces over time was also investigated. Experimentally, the junction-to- coolant thermal resistance was reduced by up to 12.5% for jet impingement on enhanced surfaces s compared to the baseline channel flow configuration. Base plate-to-coolant (convective) resistance was reduced by up to 37.0% for the jet-based configuration compared to the baseline, suggesting that while improvements to the cooling side reduce overall resistance, reducing the passive stack resistance may contribute to lowering overall junction-to-coolant resistance. Full inverter power testing showed reduced thermal resistance from the middle of the module baseplate to coolant of up to 16.5%. Between the improvement in thermal performance and pumping power, the coefficient of performance improved by up to 13% for the jet-based configuration.

  13. Effect of nodule count and cooling rate on As-Cast matrix of a Cu-Mo spheroidal graphite

    Science.gov (United States)

    Salazar F., R.; Herrera-Trejo, M.; Castro, M.; Méndez N., J.; Torres T., J.; Méndez N., M.

    1999-06-01

    The transformation of austenite to ferrite and graphite or to pearlite in spheroidal graphite cast iron depends on a number of factors, among which are the nodule count and the cooling rate. In this study, the pearlite fraction decreased as the nodule count increased for a given cooling rate. Furthermore, as the cooling rate increased, the fraction of pearlite increased. Both effects were more sensitive at low nodule count. The effects of altering these parameters on the relative amount of pearlite and ferrite in the matrix of a copper-molybdenum (Cu-Mo) spheroidal graphite cast iron were addressed using heats carried out in an induction furnace, and the melts were treated with magnesium ferrosilicon in a ladle. To vary the nodule count, the melts were inoculated with two different amounts of ferrosilicon. Pouring was performed into sand molds of cylindrical cavities with different section size in order to achieve various cooling rates. Both the nodule count and the cooling rate affected the relative amount of ferrite and pearlite in the matrix.

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

    Science.gov (United States)

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

    2014-11-01

    A successful outcome after artificial insemination with cooled semen is dependent on many factors, the sperm quality of the ejaculate being one. Previous studies have shown that spermatozoa with good motility, normal morphology, and good chromatin integrity can be selected by means of colloid centrifugation, particularly single layer centrifugation (SLC) using species-specific colloids. The purpose of the present study was to conduct an insemination trial with spermatozoa from "normal" ejaculates, i.e., from stallions with no known fertility problem, to determine whether the improvements in sperm quality seen in SLC-selected sperm samples compared with uncentrifuged controls in laboratory tests are reflected in an increased pregnancy rate after artificial insemination. In a multicentre study, SLC-selected sperm samples and uncentrifuged controls from eight stallions were inseminated into approximately 10 mares per treatment per stallion. Ultrasound examination was carried out approximately 16 days after insemination to detect an embryonic vesicle. The pregnancy rates per cycle were 45% for controls and 69% for SLC-selected sperm samples, which is statistically significant (P < 0.0018). Thus, the improvement in sperm quality reported previously for SLC-selected sperm samples is associated with an increase in pregnancy rate, even for ejaculates from stallions with no known fertility problem. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Dabbing the Skin Surface Dry During Ice Massage Augments Rate of Temperature Drop.

    Science.gov (United States)

    Sidhu, Amrik; Lentell, Gary; Pettitt, Robert W

    While ice massage (IM) is a rapid cooling technique used to facilitate therapeutic movements in the rehabilitation process, evidence of its efficacy over alternative therapeutic protocols is scarce. We determined whether dabbing the skin surface dry during a standard IM treatment would lead to greater rate of skin temperature reduction in comparison to without dabbing; and whether dabbing the skin would lead to an acute change in flexibility. Sixteen healthy volunteers received a "dabbing" and "non-dabbing" 7-minute IM treatment over the surface of each triceps surae muscle. Minute-by-minute temperature change in skin surface was evaluated using an infrared thermometer. Active (AROM) and passive (PROM) range of motion were evaluated via hand-held goniometer and passive stretch force was evaluated with an algometer. Dependent variables (reported as Mean ± SD) were tested with two-way analysis of variance with repeated measures. Skin temperature (°C) was reduced to with dabbing (5.8 ± 1.1) in comparison to without dabbing (6.8 ± 1.4), evoking significantly greater cooling at 1-min of ice massage (group X time interaction, p0.05) for either IM group. The dabbing protocol resulted in more rapid rate of temperature drop at 1-minute, however, both IM techniques are sufficient in cooling surface temperature after 2-minutes of IM. Further study is warranted to determine the clinical significance of the dabbing procedure.

  16. Effect of thawing time, cooling rate and boron nutrition on freezing point of the primordial shoot in norway spruce buds.

    Science.gov (United States)

    Räisänen, Mikko; Repo, Tapani; Lehto, Tarja

    2006-04-01

    Effects of cooling rates on bud frost hardiness have been studied but there is little information on bud responses to thawing. Since the cell wall pore size has been found to increase with boron (B) deficiency, B deficiency may affect the supercooling ability of buds in winter. The effects of duration of thawing time and rate of cooling on bud frost hardiness of Norway spruce (Picea abies) were studied in a B fertilization trial in February 2003 and March 2005. Frost hardiness of apical buds was determined by differential thermal analysis (DTA) and visual scoring of damage. In 2003, the freezing point of primordial shoots of buds (T(f)), i.e. the low-temperature exotherm (LTE), was, on average, -39 degrees C when buds were thawed for less than 3 h and the T(f) increased to -21 degrees C after 18 h of thawing. During the first 4 h of thawing, the rate of dehardening was 6 degrees C h(-1). In 2005, buds dehardened linearly from -39 degrees C to -35 degrees C at a rate of 0.7 degrees C h(-1). In 2003, different cooling rates of 1-5 degrees C h(-1) had a minor effect on T(f) but in 2005 with slow cooling rates T(f) decreased. In both samplings, at cooling rates of 2 and 1 degrees C h(-1), T(f) was slightly higher in B-fertilized than in non-fertilized trees. By contrast, at very short thawing times in 2003, T(f) was somewhat lower in B-fertilized trees. There was little evidence of reduced frost hardiness in trees with low B status. This study showed that buds deharden rapidly when exposed to above-freezing temperatures in winter, but if cooled again they reharden more slowly. According to this study, rapid dehardening of buds has to be taken into account in assessments of frost hardiness.

  17. Intravascular versus surface cooling for targeted temperature management after out-of-hospital cardiac arrest

    DEFF Research Database (Denmark)

    Glover, Guy W; Thomas, Richard M; Vamvakas, George

    2016-01-01

    BACKGROUND: Targeted temperature management is recommended after out-of-hospital cardiac arrest and may be achieved using a variety of cooling devices. This study was conducted to explore the performance and outcomes for intravascular versus surface devices for targeted temperature management after...... out-of-hospital cardiac arrest. METHOD: A retrospective analysis of data from the Targeted Temperature Management trial. N = 934. A total of 240 patients (26%) managed with intravascular versus 694 (74%) with surface devices. Devices were assessed for speed and precision during the induction......, maintenance and rewarming phases in addition to adverse events. All-cause mortality, as well as a composite of poor neurological function or death, as evaluated by the Cerebral Performance Category and modified Rankin scale were analysed. RESULTS: For patients managed at 33 °C there was no difference between...

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

    Science.gov (United States)

    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.

  19. Thermal radiation characteristics and direct evidence of tungsten cooling on the way to nanostructure formation on its surface

    International Nuclear Information System (INIS)

    Takamura, S.; Miyamoto, T.; Ohno, N.

    2013-01-01

    The physical properties of tungsten with nanostructure on its surface are investigated focusing on the thermal radiation and cooling characteristics. First, direct evidence of substantial W surface cooling has been clearly shown with use of a very thin thermocouple inserted into W target, which solves an uncertainty associated with a radiation thermometer. Second, the above measurements of W surface temperature make it possible to estimate quantitatively the total emissivity from which we may evaluate the radiative power through the Stefan–Boltzmann equation, which is very important for mitigation evaluation of a serious plasma heat load to the plasma-facing component

  20. Modeling and Thermal Performance Evaluation of Porous Curd Layers in Sub-Cooled Boiling Region of PWRs and Effects of Sub-Cooled Nucleate Boiling on Anomalous Porous Crud Deposition on Fuel Pin Surfaces

    International Nuclear Information System (INIS)

    Barclay Jones

    2005-01-01

    A significant number of current PWRs around the world are experiencing anomalous crud deposition in the sub-cooled region of the core, resulting in an axial power shift or Axial Offset Anomaly (AOA), a condition that continues to elude prediction of occurrence and thermal/neutronic performance. This creates an operational difficulty of not being able to accurately determine power safety margin. In some cases this condition has required power ''down rating'' by as much as thirty percent and the concomitant considerable loss of revenue for the utility. This study examines two aspects of the issue: thermal performance of crud layer and effect of sub-cooled nucleate boiling on the solute concentration and its influence on initiation of crud deposition/formation on fuel pin surface

  1. Near-ground cooling efficacies of trees and high-albedo surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen M. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequently-proposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object`s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by.

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

    Science.gov (United States)

    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.

  3. Optimum design for the primary cooling system in BWRs to control shutdown radiation dose rate

    International Nuclear Information System (INIS)

    Miki, Minoru; Saito, Tatsuya; Uchida, Shunsuke; Izumiya, Masakiyo.

    1982-01-01

    The reduction of radiation dose rate at the time of shutdown is an important task for smoothly performing the regular inspection and maintenance works in nuclear power plants as the number of those plants in operation has increased. Hitachi Ltd. has investigated the industrially applicable measures to reduce dose rate to suppress the exposure dose per year in 1100 MWe class BWR nuclear power plants below 200 Man-Rem. The exposure dose in normal checking works during a regular inspection is regarded to be macroscopically dependent on the dose rate of piping in recirculation system. Thus, it was found that the above target can be achieved by suppressing the dose rate on piping surface to 30 mR/h. For further reduction if iron crud and 60 Co ions contributing to the increase of dose rate, in addition to the oxygen injection into the feed water system and the duplicated condensate purification system, the use of corrosion-resistant steel and low cobalt material has been attempted. However, high temperature water to be filtrated can not be passed through the purification system because it employs ion exchange resin. Therefore, the optimum capacity is selected for the purification system in view of the reduction of dose rate and plant thermal efficiency. Hitachi Ltd. recommends the application of this system, considering the evaluation of contribution by the code predicting dose rate increase and estimating economy. The above measures will achieve the exposure dose target of 200 Man-Rem/year. (Wakatsuki, Y.)

  4. Prediction of mechanical properties of Al alloys with change of cooling rate

    Directory of Open Access Journals (Sweden)

    Quan-Zhi Dong

    2012-11-01

    Full Text Available The solidification process significantly affects the mechanical properties and there are lots of factors that affect the solidification process. Much progress has been made in the research on the effect of solidification on mechanical properties. Among them, the PF (Phase Field model and CA (Cellular Automata model are widely used as simulation methods which can predict nucleation and its growth, and the size and morphology of the grains during solidification. Although they can give accurate calculation results, it needs too much computational memory and calculation time. So it is difficult to apply the simulation to the real production process. In this study, a more practical simulation approach which can predict the mechanical properties of real aluminum alloys is proposed, by identifying through experiment the relationship between cooling rate and SDAS (Secondary Dendrite Arm Spacing and mechanical properties. The experimentally measured values and the values predicted by simulation have relatively small differences and the mechanical properties of a variety of Al alloys are expected to be predicted before casting through use of the simulation.

  5. Wetland Water Cooling Partnership: The Use of Constructed Wetlands to Enhance Thermoelectric Power Plant Cooling and Mitigate the Demand of Surface Water Use

    Energy Technology Data Exchange (ETDEWEB)

    Apfelbaum, Steven L. [Applied Ecological Services Inc., Brodhead, WI (United States); Duvall, Kenneth W. [Sterling Energy Services, LLC, Atlanta, GA (United States); Nelson, Theresa M. [Applied Ecological Services Inc., Brodhead, WI (United States); Mensing, Douglas M. [Applied Ecological Services Inc., Brodhead, WI (United States); Bengtson, Harlan H. [Sterling Energy Services, LLC, Atlanta, GA (United States); Eppich, John [Waterflow Consultants, Champaign, IL (United States); Penhallegon, Clayton [Sterling Energy Services, LLC, Atlanta, GA (United States); Thompson, Ry L. [Applied Ecological Services Inc., Brodhead, WI (United States)

    2013-12-01

    Through the Phase I study segment of contract #DE-NT0006644 with the U.S. Department of Energy’s National Energy Technology Laboratory, Applied Ecological Services, Inc. and Sterling Energy Services, LLC (the AES/SES Team) explored the use of constructed wetlands to help address stresses on surface water and groundwater resources from thermoelectric power plant cooling and makeup water requirements. The project objectives were crafted to explore and develop implementable water conservation and cooling strategies using constructed wetlands (not existing, naturally occurring wetlands), with the goal of determining if this strategy has the potential to reduce surface water and groundwater withdrawals of thermoelectric power plants throughout the country. Our team’s exploratory work has documented what appears to be a significant and practical potential for augmenting power plant cooling water resources for makeup supply at many, but not all, thermoelectric power plant sites. The intent is to help alleviate stress on existing surface water and groundwater resources through harvesting, storing, polishing and beneficially re-using critical water resources. Through literature review, development of conceptual created wetland plans, and STELLA-based modeling, the AES/SES team has developed heat and water balances for conventional thermoelectric power plants to evaluate wetland size requirements, water use, and comparative cooling technology costs. The ecological literature on organism tolerances to heated waters was used to understand the range of ecological outcomes achievable in created wetlands. This study suggests that wetlands and water harvesting can provide a practical and cost-effective strategy to augment cooling waters for thermoelectric power plants in many geographic settings of the United States, particularly east of the 100th meridian, and in coastal and riverine locations. The study concluded that constructed wetlands can have significant positive

  6. Determination of fan flow and water rate adjustment for off-design cooling tower tests

    International Nuclear Information System (INIS)

    Vance, J.M.

    1984-02-01

    The determination of the performance of a mechanical draft cooling tower requires that the air mass flow through the tower be known. Since this flow is not measured, it has been customary to use the manufacturer's design air flow and adjust it by the one-third power of the ratio of the design to test fan horsepower. The most nearly correct approximation of air flow through a tower can be obtained by incrementally moving through the tower from air inlet to outlet while calculating mass flows, energy balances, and pressure drops for each increment and then utilizing fan curves to determine volumetric and mass flows. This procedure would account for changes in air humidity and density through the tower, evaporation of water, effect of water rate on air pressure drop, and changes in fan characteristics. These type calculations may be within the capabilities of all in the near future, but for the interim, it is recommended that a more elementary approach be used which can be handled with a good calculator and without any proprietary data. This approach depends on certain assumptions which are acceptable if the tower test is conducted within CTI code requirements. The fan must be considered a constant suction volume blower for a given blade pitch. The total pressure at the fan, a function of volumetric flow and wet air density, must be assumed to be unaffected by other considerations, and the fan horsepower must be assumed to change only as volumetric flow and wet air density changes. Given these assumptions, along with design information normally provided with a tower, the determination of air flow through a tower in a test can be made from CTI test data. The air flow, and consequently the water rate adjustment and corrected water to air ratio, are derived and found to be direct functions of horsepower and density and an inverse function of wet air humidities

  7. Effect of cooling rates and Zr addition on the microstructure and corrosion behaviors of the Mg–Zn–Gd alloys

    Science.gov (United States)

    Zhang, Jinyang; Jia, Peng; Xu, Shumin; Lou, Gui; Zhou, Guorong; Zhao, Degang; Teng, Xinying

    2018-01-01

    The grain size of Mg96Zn1Gd3 alloys was refined by increasing cooling rate and adding Zr refiner. At the cooling rate of 122.8 K s‑1, the primary dendrite spacing decreased from 12.5 to 6.4 μm with the Zr addition in Mg96Zn1Gd3 alloy casting into a copper mold. At the 0.3 K s‑1, the long-period stacking ordered structure phase (LPSO) only was formed in Mg96Zn1Gd3 alloy casting into a sand mold. The research concerned on mechanical properties showed that hardness of Mg95.8Zn1Gd3Zr0.2 alloy was increased from 82.7 to 121.1 HBW with the increase of the cooling rate. About the high temperature performance, the melt temperature of the second phase was 882 K, and it was not changed with the Zr addition and the change of cooling rates. However, the excellent corrosion resistance corresponded to the large grain size was changed by the formation of the LPSO phase in Mg96Zn1Gd3 alloy.

  8. Comparative Cryopreservation of Avian Spermatozoa: Effects of Cooling and Thawing Rates on Turkey and Sandhill Crane Sperm Cryosurvival

    Science.gov (United States)

    A comparative approach using Sandhill crane (Grus Canadensis) and the domestic white turkey (Meleagridis gallopavo) was used to determine the possible benefits of variation in cooling and thawing rates and semen volume on cryoprotective efficiency. Sperm was frozen in cryovials using a range of dime...

  9. Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations

    Science.gov (United States)

    Deng, Lu; Du, Jincheng

    2018-01-01

    Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Qn distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3B and 4B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

  10. The effects of concentration and heating-cooling rate on rheological properties of Plantago lanceolata seed mucilage

    DEFF Research Database (Denmark)

    Hesarinejad, Mohammad Ali; Sami Jokandan, Maryam; Mohammadifar, Mohammad Amin

    2017-01-01

    In this study, the effect of concentration (0.5, 1, 1.5 and 2%) and heating-cooling rate (1, 5 and 10 °C min−1) on the rheological properties of Plantago lanceolata seed mucilage (PLSM) solutions were investigated. It was observed that the gum dispersions exhibited viscoelastic properties under t...

  11. Influence of Cooling Rate in High-Temperature Area on Hardening of Deposited High-Cutting Chrome-Tungsten Metal

    International Nuclear Information System (INIS)

    Malushin, N N; Valuev, D V; Valueva, A V; Serikbol, A; Borovikov, I F

    2015-01-01

    The authors study the influence of cooling rate in high-temperature area for thermal cycle of high-cutting chrome-tungsten metal weld deposit on the processes of carbide phase merging and austenite grain growth for the purpose of providing high hardness of deposited metal (HRC 64-66). (paper)

  12. The Effect of Cooling Rate on Properties of Intermetallic Phase in a Complex Al-Si Alloy

    Directory of Open Access Journals (Sweden)

    Tupaj M.

    2016-09-01

    Full Text Available The cooling rate is one of the main tools available to the process engineer by means of which it is possible to influence the crystallisation process. Imposing a desired microstructure on a casting as early as in the casting solidification phase widens significantly the scope of technological options at disposal in the process of aluminium-silicon alloy parts design and application. By changing the cooling rate it is possible to influence the course of the crystallisation process and thus also the material properties of individual microstructure components. In the study reported in this paper it has been found that the increase of cooling rate within the range of solidification temperatures of a complex aluminium-silicon alloy resulted in a decrease of values of the instrumented indentation hardness (HIT and the instrumented indentation elastic modulus (EIT characterising the intermetallic phase occurring in the form of polygons, rich in aluminium, iron, silicon, manganese, and chromium, containing also copper, nickel, and vanadium. Increased cooling rate resulted in supersaturation of the matrix with alloying elements.

  13. The surface charge of oxides and its role in deposition and transport of radioactivity in water-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Tewari, P.H.; Campbell, A.B.

    1972-01-01

    The role of surface charges in the deposition of suspended oxides on surfaces is discussed. Results of deposition of corrosion-product oxides on surfaces at room temperature and 200 o C are reported. These, together with results of the specific adsorption of Co(II) on negatively charged Fe 3 O 4 suspensions are used to explain the growth of Co-60 radiation fields in water-cooled reactors. (author)

  14. Employment of neural networks for analysis of chemical composition and cooling rate effect on CCT diagrams shape

    International Nuclear Information System (INIS)

    Dobrzanski, L.A.; Trzaska, J.

    2004-01-01

    The paper presents possibility of employment of the original supercooled austenite transformation anisothermic diagrams forecasting method for analysis of the chemical composition effect on the CCT diagrams shape. The developed model makes it possible to substitute computer simulation for the costly and time consuming experiments. The information derived from calculations make it possible to plot diagrams illustrating the effects of the particular elements or pairs of elements, as well as cooling rate and/or austenitizing temperature, on any temperature or time describing transformations in steel during its continuous cooling. Evaluation is also possible of the effect of the aforementioned factors on hardness and fractions of the particular structural constituents. (author)

  15. Theoretical assessment of evaporation rate of isolated water drop under the conditions of cooling tower of thermal power plant

    OpenAIRE

    Shevelev Sergey

    2017-01-01

    The purpose of the work is numerical modelling of heat and mass transfer at evaporation of water drops under the conditions which are typical for a modern chimney-type cooling tower of a thermal power plant. The dual task of heat and mass transfer with movable boundary at convective cooling and evaporation for a ‘drop–humid air’ system in a spherical coordinate system has been solved. It has been shown that there is a rapid decline of water evaporation rate at the initial stage of the process...

  16. INFLUENCE OF THE COOLING RATE AND THE BLEND RATIO ON THE PHYSICAL STABILTIY OF CO-AMORPHOUS NAPROXEN/INDOMETHACIN

    DEFF Research Database (Denmark)

    Beyer, Andreas; Grohganz, Holger; Löbmann, Korbinian

    2016-01-01

    Co-amorphisation represents a promising approach to increase the physical stability and dissolution rate of amorphous active pharmaceutical ingredients (APIs) as an alternative to polymer glass solutions. For amorphous and co-amorphous systems, it is reported that the preparation method and the b......Co-amorphisation represents a promising approach to increase the physical stability and dissolution rate of amorphous active pharmaceutical ingredients (APIs) as an alternative to polymer glass solutions. For amorphous and co-amorphous systems, it is reported that the preparation method...... and the blend ratio play major roles with regard to the resulting physical stability. Therefore, in the present study, co-amorphous naproxen-indomethacin (NAP/IND) was prepared by melt-quenching at three different cooling rates and at ten different NAP/IND blend ratios. The samples were analyzed using XRPD...... than samples prepared by intermediate cooling and slow cooling. Intermediate cooling was subsequently used to prepare co-amorphous NAP/IND at different blend ratios. In a previous study, it was postulated that the equimolar (0.5:0.5) co-amorphous blend of NAP/IND is most stable. However, in the present...

  17. Influence of the quenching rate and step-wise cooling temperatures on microstructural and tensile properties of PER72 ® Ni-based superalloy

    Directory of Open Access Journals (Sweden)

    Le Baillif Paul

    2014-01-01

    Full Text Available The PER72® grade is used as a wrought engine turbine disk, which is a critical high temperature component. During the heat treatment process, residual stresses are generated during the quench, which may lead to irreversible damages on the workpiece. The aim of this study is to better understand the mechanisms involved in the residual stress generation. Therefore, the influence of quenching conditions on the high temperature tensile properties and the multi-scale microstructure evolutions are investigated after cooling. PER72® specimens are annealed above the solvus temperature, directly on the servo-hydraulic testing machine. Three quenching rates are used: 30 ∘C/min, 120 ∘C/min, and 300 ∘C/min. For each condition, the cooling is interrupted at 1000 ∘C, 850 ∘C, 600 ∘C and 20 ∘C to perform isothermal tensile test. Specimens are post-mortem analysed. On one hand the fracture surface is investigated using SEM. On the other hand the microstructure evolution was observed and quantified at different scales using SEM directly on the bulk or after the chemical extraction of precipitation. The precipitation size and volume fraction statistics, X-Ray diffraction for the crystallography and composition of the different phases are investigated. It was shown that the testing temperature does not significantly influence the γ′ distribution of particles. Conversely, the γ′ precipitation is strongly influenced by the cooling rate. Notably, the average size, the distance between particles as well as the number density of γ′ precipitates are significantly modified by the cooling rate. Changes in tensile properties are related to microstructural.

  18. Effects of Undercooling and Cooling Rate on Peritectic Phase Crystallization Within Ni-Zr Alloy Melt

    Science.gov (United States)

    Lü, P.; Wang, H. P.

    2018-04-01

    The liquid Ni-16.75 at. pct Zr peritectic alloy was substantially undercooled and containerlessly solidified by an electromagnetic levitator and a drop tube. The dependence of the peritectic solidification mode on undercooling was established based on the results of the solidified microstructures, crystal growth velocity, as well as X-ray diffraction patterns. Below a critical undercooling of 124 K, the primary Ni7Zr2 phase preferentially nucleates and grows from the undercooled liquid, which is followed by a peritectic reaction of Ni7Zr2+L → Ni5Zr. The corresponding microstructure is composed of the Ni7Zr2 dendrites, peritectic Ni5Zr phase, and inter-dendritic eutectic. Nevertheless, once the liquid undercooling exceeds the critical undercooling, the peritectic Ni5Zr phase directly precipitates from this undercooled liquid. However, a negligible amount of residual Ni7Zr2 phase still appears in the microstructure, indicating that nucleation and growth of the Ni7Zr2 phase are not completely suppressed. The micromechanical property of the peritectic Ni5Zr phase in terms of the Vickers microhardness is enhanced, which is ascribed to the transition of the peritectic solidification mode. To suppress the formation of the primary phase completely, this alloy was also containerlessly solidified in free fall experiments. Typical peritectic solidified microstructure forms in large droplets, while only the peritectic Ni5Zr phase appears in smaller droplets, which gives an indication that the peritectic Ni5Zr phase directly precipitates from the undercooled liquid by completely suppressing the growth of the primary Ni7Zr2 phase and the peritectic reaction due to the combined effects of the large undercooling and high cooling rate.

  19. Development of a reliable low-cost controlled cooling rate instrument for the cryopreservation of hematopoietic stem cells.

    Science.gov (United States)

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

    2010-04-01

    An optimal cooling rate is one of the critical factors influencing the survival of cells during cryopreservation. We describe a novel device, called the box-in-box, that has been 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 degrees C freezer, a cooling rate of -1 to -3.5 degrees C/min, which has been widely used for the cryopreservation of HSC, was achieved. In order to evaluate this device further, 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 the box-in-box worked as well as the CryoMed instrument. There was no significant difference in either survival rate or the culture/colony outcome between the two devices. 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 of a wide variety of tissues and cells.

  20. A study of the rates of heat transfer and bubble site density for nucleate boiling on an inclined heating surface

    International Nuclear Information System (INIS)

    Bonamy, S.E.; Symons, J.G.

    1974-08-01

    Nucleate pool boiling of distilled water from an electrically heated surface at atmospheric pressure is studied for varying heating surface inclinations. The constants of the accepted boiling equation phi = K Tsup(B) and the Rohsenow Correlation Coefficient are found to be dependent on surface orientation. Convection cooling is observed to play a major role in pool boiling phenomena and causes large changes in the heat transfer rates for a given excess of temperature of the heated surface. Active nucleation site density is studied and found to be independent of surface inclination. Empirical relations are presented to provide an understanding of the effects of inclination on other boiling parameters. (author)

  1. Nanofluids for power engineering: Emergency cooling of overheated heat transfer surfaces

    Science.gov (United States)

    Bondarenko, B. I.; Moraru, V. N.; Sidorenko, S. V.; Komysh, D. V.

    2016-07-01

    The possibility of emergency cooling of an overheated heat transfer surface using nanofluids in the case of a boiling crisis is explored by means of synchronous recording of changes of main heat transfer parameters of boiling water over time. Two nanofluids are tested, which are derived from a mixture of natural aluminosilicates (AlSi-7) and titanium dioxide (NF-8). It is found that the introduction of a small portions of nanofluid into a boiling coolant (distilled water) in a state of film boiling ( t heater > 500°C) can dramatically decrease the heat transfer surface temperature to 130-150°C, which corresponds to a transition to a safe nucleate boiling regime without affecting the specific heat flux. The fact that this regime is kept for a long time at a specific heat load exceeding the critical heat flux for water and t heater = 125-130°C is particularly important. This makes it possible to prevent a potential accident emergency (heater burnout and failure of the heat exchanger) and to ensure the smooth operation of the equipment.

  2. Effect of Different Cooling Rates on the Corrosion Behavior of High-Carbon Pearlitic Steel

    Science.gov (United States)

    Katiyar, Prvan Kumar; Misra, Sudhir; Mondal, K.

    2018-03-01

    The present work discusses the effect of pearlitic morphology on the corrosion behavior of high-carbon fully pearlitic steel in 3.5% NaCl solution. Four different types of pearlitic steels (furnace-cooled, as-received, air-cooled and forced-air-cooled) consisting of coarse, medium, fine and very fine microstructures, respectively, were tested. Electrochemical behavior of these steels was studied with the help of dynamic and linear polarization and AC impedance spectroscopic tests. The corrosion resistance improved with fineness of the microstructure in general. However, with further reduction in interlamellar spacing beyond a limit, the corrosion resistance reduced slightly. Formation of homogeneous distribution of microgalvanic cells between cementite and ferrite lamellae of fine pearlitic steel improved the corrosion resistance. However, entanglement of the lamellae of pearlite in very fine pearlitic structure as well as breaking of cementite lamellae due to finer pearlitic colonies was attributed to the higher corrosion of the forced-air-cooled steel as compared to the air-cooled steel.

  3. Hybrid radiator cooling system

    Science.gov (United States)

    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.

  4. Effects of surface slope on erosion rates of quartz particles

    OpenAIRE

    Lodge, Phillip.

    2006-01-01

    Modeling sediment erosion is important in a wide range of environmental problems. The effects of various environmental factors on erosion rates have been studied, but the effects of surface slope on erosion rates of a wide range of sediments have not been quantified. The effects of surface slope, both in the direction of flow (pitch) and perpendicular to the flow (roll), on erosion rates of quartz particles were investigated using the Sediment Erosion at Depth Flume (Sedflume). US Navy (US...

  5. Foulant Characteristics Comparison in Recycling Cooling Water System Makeup by Municipal Reclaimed Water and Surface Water in Power Plant

    OpenAIRE

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were com...

  6. Pressure and cooling rate effect on polyhedron clusters in Cu-Al alloy by using molecular dynamics simulation

    Science.gov (United States)

    Celik, Fatih Ahmet

    2014-10-01

    In this study, the microstructural evolution of crystal-type and icosahedral (icos)-type polyhedrons in Cu-50 at%Al alloy based on the embedded atom method (EAM) model is studied at two cooling rates under normal and high pressures by using the molecular dynamics (MD) simulation method. The cluster-type index method (CTIM) which describes icos and defective icos polyhedrons and the new cluster-type index method (CTIM-2) which describes crystal-type polyhedrons have been used to perform polyhedron analysis in the model alloy system. The results of our simulations demonstrate that the effects of the cooling rate and pressure play an important role in the numbers of polyhedrons and their structures in the system.

  7. Pressure and cooling rate effect on polyhedron clusters in Cu–Al alloy by using molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Fatih Ahmet, E-mail: facelik@beu.edu.tr

    2014-10-01

    In this study, the microstructural evolution of crystal-type and icosahedral (icos)-type polyhedrons in Cu–50 at%Al alloy based on the embedded atom method (EAM) model is studied at two cooling rates under normal and high pressures by using the molecular dynamics (MD) simulation method. The cluster-type index method (CTIM) which describes icos and defective icos polyhedrons and the new cluster-type index method (CTIM-2) which describes crystal-type polyhedrons have been used to perform polyhedron analysis in the model alloy system. The results of our simulations demonstrate that the effects of the cooling rate and pressure play an important role in the numbers of polyhedrons and their structures in the system.

  8. Effect of Cooling Rate on the Microstructure and Mechanical Properties of C-Mn-Al-Si-Nb Hot-Rolled TRIP Steels

    Science.gov (United States)

    Fu, B.; Y Lu, M.; Y Yang, W.; Li, L. F.; Y Zhao, Z.

    2017-12-01

    A novel thermomechanical process to manufacture hot-rolled TRIP steels has been proposed based on dynamic transformation of undercooled austenite (DTUA). The cooling rate between DTUA and isothermal bainitic treatment in the novel process is important. In the present study, effect of this cooling rate on the final microstructures and mechanical properties of a C-Mn-Al-Si-Nb TRIP steel was investigated. The results showed that the volume fractions of acicular ferrite and retained austenite were increased with the increment of cooling rate. As a consequence, higher yield strength and larger total elongation were obtained for the investigated steel with higher cooling rate. In addition, a value of 30.24 GPa% for the product of tensile strength and total elongation was acquired when the cooling rate was 25 K/s. This value has met the standard of the “Third Generation” of advanced high strength sheet steels.

  9. Coherent structures in stratocumulus topped boundary layer: sensitivity to surface fluxes, radiative cooling and vertical stability

    Science.gov (United States)

    Davini, Paolo; D'Andrea, Fabio; Park, Seung-bu; Gentine, Pierre

    2017-04-01

    The representation of stratocumulus clouds in global climate models is still a concern for the climate modelling community. This is due to the low efficacy of current parametrization to simulate the full set of phenomena that governs the stratocumulus topped boundary layer (STBL), but also by the inaccurate knowledge of the sensitivities of the STBL dynamics to external large scale forcing. Here we show that making of a series of high-resolution LES simulations, we are able to detect and track coherent structures such as updrafts, downdrafts and their returning shells (i.e. both ascending and subsiding), together with the entraining air from the inversion layer or the free troposphere in a non-precipitating marine nighttime STBL. This is done with a new classification method based on octant analysis - using vertical velocity and two passive scalars - which defines the structures also in cloud-free regions. We are thus able to quantify the geometrical and thermodynamic characteristics (e.g. areal fraction, temperature, liquid and total water mixing ratio, buoyancy, etc.) of those structures, highlighting the single contributions to the turbulent transport of mass, heat and moisture. It is thus possible to estimate the sensitivity of the turbulent fluxes to the intensity of the cloud-top radiative cooling, to the surface latent and sensible fluxes and to the strength of the vertical stability is explored. Indeed, this analysis lays the foundation for a new parametrization of stratocumulus-topped boundary layer for global climate models.

  10. Behavior of surface integrity in cylindrical plunge grinding using different cooling systems

    Directory of Open Access Journals (Sweden)

    Leonardo Roberto Silva

    2011-01-01

    Full Text Available The superficial texture of the material can exert a decisive influence on the application and performance of the machined component. The conventional fluids used in grinding processes are environmental risk and can also be dangerous to the health. The disposal of these toxic fluids is expensive and the contamination in the proximities of the machines can present risks to the health for the personnel in the shop floor. This paper analyzes the performance of the minimum quantity lubricant (MQL technique and compares it with the conventional cooling method, developing an optimized fluid application method using a specially designed nozzle, through which a minimum amount of oil is sprayed in a compressed air flow. This paper also explores and discusses the concept of the MQL in the grinding process of hardened AISI 4340 steel. The performance of the MQL technique in grinding was evaluated based on an analysis of the surface integrity (roughness, microstructure and microhardness. As a result, it was realized that the MQL technique provides very similar characteristics to conventional process and can be applied in industry, thus contributing to an environment friendly manufacturing.

  11. Importance of surface structure on dissolution of fluorite: Implications for surface dynamics and dissolution rates

    Science.gov (United States)

    Godinho, J. R. A.; Piazolo, S.; Balic-Zunic, T.

    2014-02-01

    Dissolution rates are usually calculated as a function of surface area, which is assumed to remain constant ignoring the changes occurring on the surface during dissolution. Here we present a study of how topography of natural fluorite surfaces with different orientation changes during up to 3200 h of dissolution. Results are analyzed in terms of changes in surface area, surface reactivity and dissolution rates. All surfaces studied present fast changes in topography during the initial 200 h of dissolution. The controlling factors that cause the development of topography are the stability of the step edges forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces continue to present significant changes in topography, while for others the topography tends to remain approximately constant. The observed variation of dissolution rates are attributed to a decrease of the density of step edges on the surface and the continuous increase in exposure of more stable surfaces. Calculations of dissolution rates, which assume that dissolution rates are directly proportional to surface area, are not valid for the type of surfaces studied. Instead, to develop accurate kinetic dissolution models and more realistic stochastic dissolution simulations the surface reactivity, determined by the relative stability of the planes and type of edges that constitute a surface needs to be considered. Significant differences between dissolution rates calculated based on surface area alone, and based on surface reactivity are expected for materials with the fluorite structure.

  12. Modeling the effects of cooling rate, hydrogen content, grain refiner and modifier on microporosity formation in Al A356 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Conley, J.G.; Huang, J.; Asada, J.; Akiba, K. [Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering

    2000-06-15

    Cast Aluminum-Silicon alloys are used in numerous automotive and industrial weight sensitive applications because of their low density and excellent castability. The presence of trapped gas and or shrinkage pores in certain locations within castings has been shown to influence fatigue life. These micromechanical defects can be found most anywhere in a casting depending on processing conditions. A large amount of porosity located in the center of the cast material thickness may have no effect on mechanical properties or fatigue performance. A smaller, isolated pore near a surface may have a significant impact on mechanical properties. Hence, it is important to develop a comprehensive model to predict the size, location and distribution of microporosity in castings. In this work, we model the effect of various casting process parameters on microporosity formation for aluminum A356 alloy castings. The process parameters include cooling rate, hydrogen content, grain refiner and modifier. The proposed two-dimensional model predicts the size, morphology and distribution of microporosity at a given location in the casting. The method couples a mathematical model of porosity evolution with a probabilistic grain structure prediction model. The porosity evolution model is based on the simultaneous solution of the continuity and momentum equations for the metal and the mass conservation equation for the dissolved gas. The nucleation and growth of grains are simulated with a probabilistic method that uses the information from a heat transfer simulation, i.e. temperature and solid fraction, to determine the transition rules for grain evolution. The simulation results correlate well with experimental observation of porosity in cast structures. (orig.)

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

    Science.gov (United States)

    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.

  14. Optimization of the crystallinity of polypropylene/submicronic-talc composites: The role of filler ratio and cooling rate

    Directory of Open Access Journals (Sweden)

    A. Makhlouf

    2016-03-01

    Full Text Available Micronic and submicronic mineral fillers recently appeared as efficient reinforcing agents for polyolefins in addition to the benefit of bypassing the exfoliation/dispersion problem encountered in the case of incorporation of nanoscopic fillers such as clay. Submicronic-talc, designated as μ-talc, belongs to this kind of new fillers. This work was aimed at searching to optimize the crystallinity ratio of isotactic polypropylene in the presence of μ-talc in relation to the filler ratio of the composites and the cooling rate from the melt. In order to highlight the efficiency of the μ-talc on the crystallization of polypropylene comparison has been made with PP composites containing conventional talc particles. The study has been carried out on samples having μ-talc weight fractions covering the range 3–30%. In the context of optimizing the crystallinity ratio of the polypropylene matrix in the composites, calorimetric experiments have been planned using a full factorial design. The results were statistically processed by analysis of the variance via mathematical models for predicting the crystallinity ratio in relation to the cooling rate and the filler ratio. Contour graphs have been plotted to determine the effect of each parameter on crystallinity. The cooling rate proved to have a significantly stronger influence on crystallinity than the type and content of filler.

  15. Effects of cooling rate on vermicular graphite percentage in a brake drum produced by one-step cored wire injection

    Directory of Open Access Journals (Sweden)

    Yu-shuang Feng

    2015-09-01

    Full Text Available In this research, a vermicular graphite cast iron brake drum was produced by cored wire injection in a one-step method. Silica sand and low-density alumina-silicate ceramic were used as molding materials in order to investigate the effect of cooling rate on percentage of vermicular graphite and mechanical properties of the brake drum casting. Several thermocouples were inserted into the casting in the desired positions to measure the temperature change. By means of one-step cored wire injection, the two residual concentrations of Mg and RE were effectively controlled in the ranges of 0.013%-0.017% and 0.019%-0.025%, respectively, which are crucial for the production of vermicular graphite cast iron and the formation of vermicular graphite. In addition, the cooling rate had a significant effect on the vermicular graphite percentage. In the case of the silica mold brake drum casting, there was an obvious difference in the cooling rate with the wall change, leading to a change in vermicular graphite percentage from 70.8% to 90%. In the low-density alumina-silicate ceramic mold casting, no obvious change in temperature was detected by the thermocouples and the percentage of the vermicular graphite was stable at 85%. Therefore, the vermicular graphite cast iron brake drum with a better combination of mechanical properties could be obtained.

  16. A method for measuring the corrosion rate of materials in spallation neutron source target/blanket cooling loops

    International Nuclear Information System (INIS)

    Lillard, R.S.; Butt, D.P.

    1999-01-01

    This paper summarizes the ongoing evaluation of the susceptibility of materials in accelerator target/blanket cooling loops to corrosion. To simulate the exposure environment in a target/blanket cooling loop, samples were irradiated by an 800 MeV proton beam at the A6 Target Station of the Los Alamos Neutron Science Center (LANSCE). To accomplish this, a cooling water loop capable of exposing corrosion samples to an 800 MeV proton beam at currents upwards of 1 mA was constructed. This loop allowed control and evaluation hydrogen water chemistry, water conductivity, and solution pH. Specially designed ceramic sealed samples were used to measure the real-time corrosion rates of materials placed directly in the proton beam using electrochemical impedance spectroscopy (EIS). EIS was also used to measure real-time corrosion rates of samples that were out of the proton beam and downstream from the in-beam samples. These out-of-beam probes primarily examined the effects of long lived water radiolysis products from proton irradiation on corrosion rates. An overview of the LANSCE corrosion loop, the corrosion probes, and data from an in-beam alloy 718 probe are presented

  17. Wind dependence on the flow rate in a natural draught cooling tower

    International Nuclear Information System (INIS)

    Baer, E.; Ernst, G.; Wurz, D.

    1981-01-01

    The efficiency of a natural draught cooling tower depends, among other things, on the effect of the wind on the flow in the tower stack. Determinations were made on a natural draught wet cooling tower 100 metres high, for the purpose of studying this effects. As characteristic quantity, a typical height was determined, the values of which were worked out from the results of the measurements. The efficiency of the stack is affected the most in the case of average wind velocities (when the velocity of the wind is about equal to the mean velocity of the plume). This effect diminishes when the velocity of the wind increases. In the case of average wind velocities, the direction of the wind has an effect, owing to the neighbouring buildings; for slightly greater wind velocities, no effect could be found [fr

  18. Experimental investigation on the effects of cooling system on surface quality in high speed milling of an aluminium alloy

    Science.gov (United States)

    Chirita, B.; Tampu, N. C.; Brabie, G.; Radu, M. C.

    2016-08-01

    Surface quality is often an important feature of industrial products, not only from the impact it has on the aesthetic aspect but also for the functional role of the parts. High quality surface increases corrosion resistance, assures a longer life cycle for the product and lowers the wear. For a machined part, surface quality is influenced by a series of factors such as the material of the part, the process type, tool geometry, cutting parameters or the cooling system. The choice of the cooling system is especially important, taking into account that the proper conditions will not only assure a superior surface quality, but will also lower the costs and reduce the environmental impact and health risks. The present study aims to investigate the performance of the cooling system and the effect of the cutting parameters on the characteristics of the surfaces resulted from high speed face milling of some parts made of Al 7050-T7451 aluminium alloy. Dry cutting conditions and minimum quantity lubrication (MQL) where used. The results were analysed using analysis of variance (ANOVA).

  19. Properties of water surface discharge at different pulse repetition rates

    International Nuclear Information System (INIS)

    Ruma,; Yoshihara, K.; Hosseini, S. H. R.; Sakugawa, T.; Akiyama, H.; Akiyama, M.; Lukeš, P.

    2014-01-01

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H 2 O 2 ) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H 2 O 2 and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  20. A GTA Welding Cooling Rate Analysis on Stainless Steel and Aluminum Using Inverse Problems

    Directory of Open Access Journals (Sweden)

    Elisan dos Santos Magalhaes

    2017-01-01

    Full Text Available This work presents an analysis of the thermal influence of the heat transfer by convection and radiation during GTA (gas tungsten arc welding process. The authors’ in-house C++ previously-developed code was modified to calculate the amount of heat transfer by convection and radiation. In this software, an iterative Broydon-Fletcher-Goldfarb-Shanno (BFGS inverse method was applied to estimate the amount of heat delivered to the plate when the appropriate sensitivity criteria were defined. The methodology was validated by accomplishing lab-controlled experiments on stainless steel AISI 304L and aluminum 6065 T5 plates. Due to some experimental singularities, the forced thermal convection induced by the electromagnetic field and thermal-capillary force were disregarded. Significant examples of these singularities are the relatively small weld bead when compared to the sample size and the reduced time of the welding process. In order to evaluate the local Nusselt number, empirical correlations for flat plates were used. The thermal emission was a dominant cooling effect on the aluminum cooling. However, it did not present the same behavior as the stainless steel samples. The study found that the heat losses by convection and radiation of the weld pool do not affect the cooling process significantly.

  1. Recent surface cooling in the Yellow and East China Seas and the associated North Pacific climate regime shift

    Science.gov (United States)

    Kim, Yong Sun; Jang, Chan Joo; Yeh, Sang-Wook

    2018-03-01

    The Yellow and East China Seas (YECS) are widely believed to have experienced robust, basin-scale warming over the last few decades. However, the warming reached a peak in the late 1990s, followed by a significant cooling trend. In this study, we investigated the characteristics of this low-frequency sea surface temperature (SST) variance and its dynamic relationship with large-scale climate variability through cyclostationary orthogonal function analysis for the 1982-2014 period. Both regressed surface winds on the primary mode of the YECS SST and trends in air-sea heat fluxes demonstrate that the intensification of the northerly winds in winter contribute largely to the recent cooling trend by increasing heat loss to the atmosphere. As a localized oceanic response to these winds, the upwind flow seems to bring warm waters and partially counteracts the basin-scale cooling, thus contributing to a weakening of the cooling trend along the central trough of the Yellow Sea. In the context of the large-scale climate variabilities, a strong relationship between the YECS SST variability and Pacific Decadal Oscillation (PDO) became weak considerably during the recent cooling period after the late 1990s as the PDO signals appeared to be confined within the eastern basin of the North Pacific in association with the regime shift. In addition to this decoupling of the YECS SST from the PDO, the intensifying Siberian High pressure system likely caused the enhanced northerly winds, leading to the recent cooling trend. These findings highlight relative roles of the PDO and the Siberian High in shaping the YECS SST variance through the changes in the large-scale atmospheric circulation and attendant oceanic advection.

  2. Tropical cooling of the ocean surface during the Last Glacial Maximum

    Science.gov (United States)

    Bard, Edouard

    2013-04-01

    Many studies have shown the importance of a correct evaluation of the mean tropical cooling to estimate the relative impact of climate forcings during the LGM, notably the effect of lower concentrations of atmospheric greenhouse gases, and in turn, have applied these results to quantify the so-called equilibrium climate sensitivity (ECS) to a CO2 doubling. Several geochemical paleothermometers have been used to estimate the tropical sea surface temperatures (e.g. SST based on alkenones and magnesium/calcium ratios measured in ocean sediments) that can be compared with model estimates (e.g. Bard 1999 Science for a short discussion). For alkenones, the TEMPUS group (Rosell-Mele et al. 2004 GRL) and MARGO group (Waelbroeck et al. Nat. Geo. 2009) used a linear equation of UK37' vs. SST based on the global core top calibration compiled by Müller et al. (1998 GCA). This calibration is indistinguishable from the original calibration based on Emiliana huxleyi cultures (Prahl et al. 1988 GCA). However, it has also been shown that the warm end of the UK37' calibration is flatter than indicated by a single straight line over the full SST range. For the warm end, this started with our study by Sonzogni et al. (1997 QR) based on low-latitude core tops from the Indian Ocean including samples representing SST between 24 and 30°C. This UK37' versus SST linear equation has a reduced slope (0.023/°C) when compared to that (0.033/°C) derived from the linear equation based on core tops compiled from all oceans (Müller et al. 1998). Support for this complexity also comes from close inspection of the global compilation by Müller et al., suggesting that the relationship flattens out at high temperatures (see also Pelejero & Calvo 2003 G3). In addition, culture studies of different strains of Gephyrocapsa oceanica and E. huxleyi (Conte et al., 1998 GCA) and measurements of sinking particulate matter from Bermuda (Conte et al. 2001 GCA) strongly suggest that the real shape of the UK

  3. Transient heat transfer performance of stainless steel structured surfaces combined with air-water spray evaporative cooling at high temperature scenarios

    International Nuclear Information System (INIS)

    Aamir, Muhammad; Qiang, Liao; Hong, Wang; Xun, Zhu; Wang, Jiaqiu; Sajid, Muhammad

    2017-01-01

    Highlights: • All boiling regimes were clearly observed for all experiments performed in initial sample temperature range 600–900 °C. • Highest cooling rate of 166.21 °C/sec is achieved with wide square fin structured surface. • An enhancement of 47.1, 50.3, 60.1 and 67.1% in burnt out heat for wide square fin structured surface has been achieved. • A sharp increase in heat transfer coefficient is observed when cooling process enter into nucleate boiling regime. • Boiling Number for pyramid narrow fin and square wide fine is higher than smooth flat surface. - Edited Abstract: The objective of the study is to enhance heat transfer performance of stainless steel structured surfaces with different geometries at different initial sample temperature (T s ) under air-water spray having constant spray parameters. Square fin, straight fin and pyramid fin (2 geometries each) are machined on stainless steel blocks. A smooth reference surface (FL) is used as base line. Commercial inverse heat conduction solver INTEMP is used to estimate the time-varying surface heat flux and surface temperature. Burnout heat flux (q b ) and critical heat flux (q c ) showed significant increase for wide square fin (Sq-W) sample at all tested sample temperatures with respect to smooth reference surface. The highest cooling rate of 166 °C/sec was achieved with Sq-W sample for T s = 900 °C. In addition, heat transfer coefficient, h increases gradually with decreasing surface super heat (ΔT). A sharp increase in heat transfer coefficient is observed when cooling process enter into nucleate boiling regime. Wide square fin structured surface showed h-curve sharp increase in nucleate boiling regime earlier than other tested samples. Boiling Number (B o ) for pyramid narrow fin (Py-N) and square wide fin (Sq-W) is higher than smooth flat surface (FL). - Abstract: The objective of the study is to enhance heat transfer performance of stainless steel structured surfaces with different

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

    International Nuclear Information System (INIS)

    Tilocca, Antonio

    2013-01-01

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

  5. Expanded calculation of weak-interaction-mediated neutrino cooling rates due to 56Ni in stellar matter

    International Nuclear Information System (INIS)

    Nabi, Jameel-Un

    2010-01-01

    An accurate estimate of the neutrino cooling rates is required in order to study the various stages of stellar evolution of massive stars. Neutrino losses from proto-neutron stars play a crucial role in deciding whether these stars would be crushed into black holes or explode as supernovae. Both pure leptonic and weak-interaction processes contribute to the neutrino energy losses in stellar matter. At low temperatures and densities, the characteristics of the early phase of presupernova evolution, cooling through neutrinos produced via the weak interaction, are important. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has recently been used with success for the calculation of stellar weak-interaction rates of fp-shell nuclide. The lepton-to-baryon ratio (Y e ) during early phases of stellar evolution of massive stars changes substantially, mainly due to electron captures on 56 Ni. The stellar matter is transparent to the neutrinos produced during the presupernova evolution of massive stars. These neutrinos escape the site and assist the stellar core in maintaining a lower entropy. Here, an expanded calculation of weak-interaction-mediated neutrino and antineutrino cooling rates due to 56 Ni in stellar matter using the pn-QRPA theory is presented. This detailed scale is appropriate for interpolation purposes and is of greater utility for simulation codes. The calculated rates are compared with earlier calculations. During the relevant temperature and density regions of stellar matter the reported rates show few differences compared with the shell model rates and might contribute in fine-tuning of the lepton-to-baryon ratio during the presupernova phases of stellar evolution of massive stars.

  6. Rate-Dependent Slip of Newtonian Liquid at Smooth Surfaces

    International Nuclear Information System (INIS)

    Zhu, Yingxi; Granick, Steve

    2001-01-01

    Newtonian fluids were placed between molecularly smooth surfaces whose spacing was vibrated at spacings where the fluid responded as a continuum. Hydrodynamic forces agreed with predictions from the no-slip boundary condition only provided that flow rate (peak velocity normalized by spacing) was low, but implied partial slip when it exceeded a critical level, different in different systems, correlated with contact angle (surface wettability). With increasing flow rate and partially wetted surfaces, hydrodynamic forces became up to 2--4 orders of magnitude less than expected by assuming the no-slip boundary condition that is commonly stated in textbooks

  7. Study on turbulence characteristics of free surface flow for cooling of fusion reactors, accelerator targets and reactor safety

    International Nuclear Information System (INIS)

    Yusuke, Ishii; Atsuhiro, Nishino; Minoru, Takahashi

    2001-01-01

    For the development of innovative fusion reactors, we examine the film flow along the first wall to simplify blanket and reduce the cost. A film flow is formed in primary cooling circuits of the light water reactors (LWR) when the loss of coolant accident (LOCA) occurs and a cold water is injected into the primary systems. In order to estimate the interfacial condensation rate at the developing region, it is required to have the knowledge about interfacial turbulent thermal diffusion of a thick film flow. Therefore, these systems have the same problem of heat transfer and transport inside the film flows. It is necessary to investigate the velocity and turbulence characteristics that have a close relation to the heat transfer and transport. Although there have been performed various studies on turbulence structure having free surface in a fully developed flow region, the turbulence properties of the film flows in a developing flow region has not been investigated sufficiently. Thus, we measure the velocity profiles and velocity fluctuations in a developing flow region using Laser Doppler Velocimeter (LDV). Then, experimental data are compared with analytical result that is obtained using the k-ε model of turbulence. (author)

  8. Feasibility Study of Venus Surface Cooling Using Chemical Reactions with the Atmosphere

    Science.gov (United States)

    Evans, Christopher

    2013-01-01

    A literature search and theoretical analysis were conducted to investigate the feasibility of cooling a craft on Venus through chemical reformation of materials from the atmosphere. The core concept was to take carbon dioxide (CO2) from the Venus atmosphere and chemically reform it into simpler compounds such as carbon, oxygen, and carbon monoxide. This process is endothermic, taking energy from the surroundings to produce a cooling effect. A literature search was performed to document possible routes for achieving the desired reactions. Analyses indicated that on Venus, this concept could theoretically be used to produce cooling, but would not perform as well as a conventional heat pump. For environments other than Venus, the low theoretical performance limits general applicability of this concept, however this approach to cooling may be useful in niche applications. Analysis indicated that environments with particular atmospheric compositions and temperatures could allow a similar cooling system to operate with very good performance. This approach to cooling may also be useful where the products of reaction are also desirable, or for missions where design simplicity is valued. Conceptual designs for Venus cooling systems were developed using a modified concept, in which an expendable reactant supply would be used to promote more energetically favorable reactions with the ambient CO2, providing cooling for a more limited duration. This approach does not have the same performance issues, but the use of expendable supplies increases the mass requirements and limits the operating lifetime. This paper summarizes the findings of the literature search and corresponding analyses of the various cooling options.

  9. Effect of Cooling Rates on the Transformation Behavior and Mechanical Properties of a Ni-Rich NiTi Alloy

    Science.gov (United States)

    Coan, Stephen; Shamimi, Ali; Duerig, T. W.

    2017-12-01

    Slightly nickel-rich Ni-Ti alloys (typically 50.5-51% atomic percent nickel) are commonly used to produce devices that are superelastic at body temperature. This excess nickel can be tolerated in the NiTi matrix when its temperature is above the solvus of about 600 °C, but will precipitate out during lower temperatures. Recent work has been done on exploring the effect lower temperatures have on the material properties of NiTi. Findings showed that properties begin to change at temperatures as low as 100 °C. It is because of these results that it was deemed important to better understand what may be happening during the quenching process itself. Through running a combination of DSC and tensile tests on samples cooled at varying rates, it was found that the cooling rate has an effect on properties when heat treated above a specific temperature. Understanding how quickly the alloy must be cooled to fully retain the supersaturated NiTi matrix is important to optimizing processes and anticipating material properties after a heat treatment.

  10. The effect of the melting spinning cooling rate on transformation temperatures in ribbons Ti-Ni-Cu shape memory

    International Nuclear Information System (INIS)

    Ramos, A.P.; Castro, W.B.; Anselmo, G.C. dos S.

    2014-01-01

    Ti-Ni-Cu alloys have been attracting attention by their high performance of shape memory effect and decrease of thermal and stress hysteresis in comparison with Ti-Ni binary alloys. One important challenge of microsystems design is the implementation of miniaturized actuation principles efficient at the micro-scale. Shape memory alloys (SMAs) have early on been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be processed at the micro-scale. Shape memory characteristics of Ti-37,8Cu-18,7Ni alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change of the velocity of cooling wheel from 21 to 63 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on austenitic and martensitic transformations behaviors is discussed. (author)

  11. Improved Count Rate and Resolution Performance of a Thermoelectrically Cooled Si(Li) X-ray Detector.

    Science.gov (United States)

    Barkan; Ihrig; Abott

    1999-03-01

    : A new energy-dispersive spectrometer Si(Li) detector for microanalysis applications, cooled by a thermoelectric (Peltier) refrigerator, was significantly improved with regard to the resolution and high count-rate performance. This new detector was mounted on a JEOL 6400 scanning electron microscope, and several application tests were run to analyze its performance. The common resolution test using an Fe55 radioactive source was performed, and it was compared with the conventional liquid nitrogen (LN) detector. The resolution at low and high count-rate was found to be slightly less than the LN detector's performance; however, these differences are minor and most application requirements were easily met. The thermoelectric cooling mechanism was found to be stable and reliable with no degradation in its performance recorded during several years of use. The collected data show improved performance by the new thermoelectrically cooled (TEC) detector compared with the old TEC design and underscore performance very close to the LN product. For most microanalysis applications, the new TEC X-ray detector can easily replace the LN detector and avoid the maintenance associated with LN filling.

  12. The cooling rates comparison between the longwave radiation and turbulence in nocturnal planetary boundary layer

    OpenAIRE

    Grisogono, Branko; Subanović, Nebojša; Koračin, Darko

    1989-01-01

    It is shown that the process of the air-cooling is dominated by the divergence of the longwave radiative flux in cases of night-time clear-sky conditions and with weak wind conditions. The parameterization of the longwave radiative flux divergence is derived according to the emissivity concept and the Stefan-Boltzman law, assuming that the water vapor is the only absorber of longwave radiative. The parameterization of the turbulent temperature flux divergence has been based on the O’Brie...

  13. The influence of cooling techniques on cutting forces and surface roughness during cryogenic machining of titanium alloys

    Directory of Open Access Journals (Sweden)

    Wstawska Iwona

    2016-12-01

    Full Text Available Titanium alloys are one of the materials extensively used in the aerospace industry due to its excellent properties of high specific strength and corrosion resistance. On the other hand, they also present problems wherein titanium alloys are extremely difficult materials to machine. In addition, the cost associated with titanium machining is also high due to lower cutting velocities and shorter tool life. The main objective of this work is a comparison of different cooling techniques during cryogenic machining of titanium alloys. The analysis revealed that applied cooling technique has a significant influence on cutting force and surface roughness (Ra parameter values. Furthermore, in all cases observed a positive influence of cryogenic machining on selected aspects after turning and milling of titanium alloys. This work can be also the starting point to the further research, related to the analysis of cutting forces and surface roughness during cryogenic machining of titanium alloys.

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

    Science.gov (United States)

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

    2000-10-01

    Potential factors influencing spermatozoa survival to cryopreservation and thawing were analyzed across a range of the following avian species: domestic chicken (Gallus domesticus), domestic turkey (Meleagris gallopavo), golden eagle (Aquila chrysaetos), Bonelli's eagle (Hieraaetus fasciatus), imperial eagle (Aquila adalberti), and peregrine falcon (Falco peregrinus). Studies focused on spermatozoa tolerance to the following: 1) osmotic stress, 2) different extracellular concentrations of the cryoprotectant dimethylacetamide (DMA), 3) equilibration times of 1 versus 4 h, 4) equilibration temperature of 4 versus 21 degrees C, and 5) rapid versus slow cooling before cryopreservation and standard thawing. Sperm viability was assessed with the live/dead stain (SYBR-14/propidium iodine). Sperm viability at osmolalities >/=800 mOsm was higher (P: or =2.06 M), experienced decreased (P: < 0. 05) spermatozoa survival in all species, except the golden eagle and peregrine falcon. Number of surviving spermatozoa diminished progressively with increasing DMA concentrations in all species. Increased equilibration temperature (from 4 to 21 degrees C) markedly reduced (P: < 0.05) spermatozoa survival in all species except the Bonelli's eagle and turkey. Rapid cooling was detrimental (P: < 0.05) to spermatozoa from all species except the imperial eagle and the chicken. These results demonstrate that avian spermatozoa differ remarkably in response to osmotic changes, DMA concentrations, equilibration time, temperature, 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.

  15. Net Reaction Rate and Neutrino Cooling Rate for the Urca Process in Departure from Chemical Equilibrium in the Crust of Fast-accreting Neutron Stars

    Science.gov (United States)

    Wang, Wei-Hua; Huang, Xi; Zheng, Xiao-Ping

    We discuss the effect of compression on Urca shells in the ocean and crust of accreting neutron stars, especially in superbursting sources. We find that Urca shells may be deviated from chemical equilibrium in neutron stars which accrete at several tenths of the local Eddington accretion rate. The deviation depends on the energy threshold of the parent and daughter nuclei, the transition strength, the temperature, and the local accretion rate. In a typical crust model of accreting neutron stars, the chemical departures range from a few tenths of kBT to tens of kBT for various Urca pairs. If the Urca shell can exist in crusts of accreting neutron stars, compression may enhance the net neutrino cooling rate by a factor of about 1-2 relative to the neutrino emissivity in chemical equilibrium. For some cases, such as Urca pairs with small energy thresholds and/or weak transition strength, the large chemical departure may result in net heating rather than cooling, although the released heat can be small. Strong Urca pairs in the deep crust are hard to be deviated even in neutron stars accreting at the local Eddington accretion rate.

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

    Science.gov (United States)

    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.

  17. The historical development of heat transfer surfaces for gas-cooled reactors analysed with a simple criterion

    International Nuclear Information System (INIS)

    Leslie, D.C.

    1980-01-01

    The evolution of finned heat transfer surfaces for gas-cooled reactors, from longitudinal through transverse to the sophisticated helical polyzonal and herring-bone fins, is described, and their merits are compared using a simple criterion of heat transfer efficiency. These fins cannot be used in AGR's because of the high neutron absorption and low thermal conductivity of stainless steel, and artificial roughening in the form of ribbing is used instead; the same criterion can be applied to this type of surface. The interest of the material is largely historical. (author)

  18. Observed radiative cooling over the Tibetan Plateau for the past three decades driven by snow cover-induced surface albedo anomaly

    Science.gov (United States)

    Chen, Xiaona; Long, Di; Hong, Yang; Liang, Shunlin; Hou, Aizhong

    2017-06-01

    Seasonal snow cover on the Tibetan Plateau (TP) is a sensitive indicator of climate change. Unlike the decreasing snow cover extent and associated weakening of radiative cooling effects for the Northern Hemisphere during recent decades reported by previous studies, snow cover variability over the TP and its impact on the energy budget remain largely unknown. We defined the snow cover-induced radiative forcing (SnRF) as the instantaneous perturbation to Earth's shortwave radiation at the top of the atmosphere (TOA) induced by the presence of snow cover. Here using satellite observations and a radiative kernel approach, we found slightly enhanced SnRF, i.e., a radiative cooling effect on the TP during the past three decades (1982-2014). However, this cooling effect weakened during 2001-2014 because of reduced snow cover at a rate of -0.61% decade-1 and land surface albedo at a rate of -0.72% decade-1. Changes in snow cover fraction are highly correlated with anomalies in land surface albedo (as) over the TP both spatially and temporally. Moreover, the SnRF is closely related to the direct observation of TOA shortwave flux anomalies (R2 = 0.54, p = 0.004) over the TP during 2001-2014. Despite the insignificant interannual variability in SnRF, its intra-annual variability has intensified driven mostly by enhanced SnRF during the snow accumulation season but weakened SnRF during the melt season, indicating greater energy release during the transition between accumulation and melt seasons. This may pose a great challenge to snow meltwater use and flood prediction for transboundary rivers originating from the TP, such as the Brahmaputra River basin.

  19. Microcanonical rates, gap times, and phase space dividing surfaces

    NARCIS (Netherlands)

    Ezra, Gregory S.; Waalkens, Holger; Wiggins, Stephen

    2009-01-01

    The general approach to classical unimolecular reaction rates due to Thiele is revisited in light of recent advances in the phase space formulation of transition state theory for multidimensional systems. Key concepts, such as the phase space dividing surface separating reactants from products, the

  20. Indexing Glomerular Filtration Rate to Body Surface Area

    DEFF Research Database (Denmark)

    Redal-Baigorri, Belén; Rasmussen, Knud; Heaf, James Goya

    2014-01-01

    BACKGROUND: Kidney function is mostly expressed in terms of glomerular filtration rate (GFR). A common feature is the expression as ml/min per 1.73 m(2) , which represents the adjustment of the individual kidney function to a standard body surface area (BSA) to allow comparison between individuals...

  1. Influence of deposition rate on PL spectrum and surface morphology ...

    Indian Academy of Sciences (India)

    Influence of deposition rate on PL spectrum and surface morphology of ZnO nanolayers deposited on Si (100) substrate. A ZENDEHNAM. ∗. , M MIRZAEE and S MIRI. Thin Film Laboratory, Department of Physics, Faculty of Science, Arak University, Arak 38156-8-8349, Iran. MS received 26 March 2012; revised 5 May 2012.

  2. HYBRID COOLING SYSTEM FOR INDUSTRIAL APPLICATION

    African Journals Online (AJOL)

    ES Obe

    1980-03-01

    Mar 1, 1980 ... ABSTRACT. A hybrid cooling System was constructed and tested for glass-ware and plastic-ware production. The unit utilizes water-in-air stream to cool molds in glass and plastic forming processes. The rate of heat transfer between the mold surface and the two component two-phase stream was.

  3. Experimental Investigation of Convective Heat Transfer during Night Cooling with Different Ventilation Systems and Surface Emissivities

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2013-01-01

    Night-time ventilation is a promising approach to reduce the energy needed for cooling buildings without reducing thermal comfort. Nevertheless actual building simulation tools have showed their limits in predicting accurately the efficiency of night-time ventilation, mainly due to inappropriate...

  4. Effects of surface finish and mechanical training on Ni-Ti sheets for elastocaloric cooling

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Tusek, Jaka; Sanna, Simone

    2016-01-01

    Elastocaloric cooling has emerged as a promising alternative to vapor compression in recent years. Although the technology has the potential to be more efficient than current technologies, there are many technical challenges that must be overcome to realize devices with high performance and accep...

  5. Two strategies of lowering surface deformations of internally cooled X-ray optics

    Czech Academy of Sciences Publication Activity Database

    Oberta, Peter; Áč, V.; Hrdý, Jaromír

    2013-01-01

    Roč. 729, NOV (2013), s. 302-306 ISSN 0168-9002 R&D Projects: GA MPO FR-TI1/412 Institutional support: RVO:68378271 Keywords : internal cooling * X-ray optics * monochromator Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.316, year: 2013

  6. Effect of cooling rate on the transition temperature in Bi-Pb-Sr-Ca-Cu-O system

    International Nuclear Information System (INIS)

    Wang Yugui; Wang Jinsong; Wang Nanlin; Jiao Xinping; Han Guchang; Chen Zhaojia; Wang Keqin; Wu Xiaoguang

    1989-12-01

    The resistance and a.c. susceptibility measurement show that cooling rate of the cast-annealing samples in heat treatment process has some effect on the 110K superconducting phase in Bi-Pb-Sr-Ca-Cu-O system. Rapid quenching of the sample in air from 845 deg C causes oxygen deficiency in lattice and brings about a trifling change of unit cell size along c-axis direction. The d.c. magnetization and specific heat anomaly Δc measurements demostrate that fast cooling rate can reduce the transition temperature of high-T c phase and the lower critical field, and weaken the pinning forces for vertex lines. The peak value of specific heat anomaly of the sample with nominal composition of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 4.5 O v is still small in comparison with YBa 2 Cu 3 O 7 . From the magnetization curve the authors estimate that the superconducting volume fraction is about 20%

  7. Rate and extent of aqueous perchlorate removal by iron surfaces.

    Science.gov (United States)

    Moore, Angela M; De Leon, Corinne H; Young, Thomas M

    2003-07-15

    The rate and extent of perchlorate reduction on several types of iron metal was studied in batch and column reactors. Mass balances performed on the batch experiments indicate that perchlorate is initially sorbed to the iron surface, followed by a reduction to chloride. Perchlorate removal was proportional to the iron dosage in the batch reactors, with up to 66% removal in 336 h in the highest dosage system (1.25 g mL(-1)). Surface-normalized reaction rates among three commercial sources of iron filings were similar for acid-washed samples. The most significant perchlorate removal occurred in solutions with slightly acidic or near-neutral initial pH values. Surface mediation of the reaction is supported by the absence of reduction in batch experiments with soluble Fe2+ and also by the similarity in specific reaction rate constants (kSA) determined for three different iron types. Elevated soluble chloride concentrations significantly inhibited perchlorate reduction, and lower removal rates were observed for iron samples with higher amounts of background chloride contamination. Perchlorate reduction was not observed on electrolytic sources of iron or on a mixed-phase oxide (Fe3O4), suggesting that the reactive iron phase is neither pure zerovalent iron nor the mixed oxide alone. A mixed valence iron hydr(oxide) coating or a sorbed Fe2+ surface complex represent the most likely sites for the reaction. The observed reaction rates are too slow for immediate use in remediation system design, but the findings may provide a basis for future development of cost-effective abiotic perchlorate removal techniques.

  8. Heat and mass transfer are in the interaction of multi-pulsed spray with vertical surfaces in the regime of evaporative cooling

    Science.gov (United States)

    Karpov, P. N.; Nazarov, A. D.; Serov, A. F.; Terekhov, V. I.

    2017-10-01

    Sprays with a periodic supply drop phase have great opportunities to control the processes of heat transfer. We can achieve optimal evaporative modes of cooling by changing the pulse duration and the repetition frequency while minimizing flow of the liquid phase. Experimental data of investigation of local heat transfer for poorly heated large surface obtained on the original stand with multi nozzle managed the irrigation system impact of the gas-droplet flow present in this work. Researches on the contribution to the intensification of spray options were conducted. Also the growth rate was integral and local heat. Information instantaneous distribution of the heat flux in the description of the processes have helped us. Managed to describe two basic modes of heat transfer: Mode “insular” foil cooling and thick foil with forming of streams. Capacitive sensors allow to monitor the dynamics of the foil thickness, the birth-belt flow, forming and the evolution of waves generated by “bombing” the surface with the droplets.

  9. Effective water cooling of very hot surfaces during the LOCA accident.

    Czech Academy of Sciences Publication Activity Database

    Štepánek, J.; Bláha, V.; Dostál, V.; Entler, Slavomír

    2017-01-01

    Roč. 124, November (2017), s. 1211-1214 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] Institutional support: RVO:61389021 Keywords : LOCA * Quenching * Divertor cooling * Heat transfer * Rewetting Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.319, year: 2016 http://www.sciencedirect.com/science/article/pii/S0920379617303733

  10. Foulant Characteristics Comparison in Recycling Cooling Water System Makeup by Municipal Reclaimed Water and Surface Water in Power Plant

    Science.gov (United States)

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS), protein (PN), and polysaccharide (PS) in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water. PMID:25893132

  11. Foulant Characteristics Comparison in Recycling Cooling Water System Makeup by Municipal Reclaimed Water and Surface Water in Power Plant

    Directory of Open Access Journals (Sweden)

    Xu Ping

    2015-01-01

    Full Text Available Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS, protein (PN, and polysaccharide (PS in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water.

  12. Effect of cooled hyperbaric bupivacaine on unilateral spinal anesthesia success rate and hemodynamic complications in inguinal hernia surgery.

    Science.gov (United States)

    Tomak, Yakup; Erdivanli, Basar; Sen, Ahmet; Bostan, Habib; Budak, Ersel Tan; Pergel, Ahmet

    2016-02-01

    We hypothesized that cooling hyperbaric bupivacaine from 23 to 5 °C may limit the intrathecal spread of bupivacaine and therefore increase the success rate of unilateral spinal anesthesia and decrease the rate of hemodynamic complications. A hundred patients scheduled for elective unilateral inguinal hernia surgery were randomly allocated to receive 1.8 ml of 0.5 % hyperbaric bupivacaine intrathecally at either 5 °C (group I, n = 50) or at 23 °C (group II, n = 50). Following spinal block at the L2-3 interspace, the lateral decubitus position was maintained for 15 min. Unilateral spinal anesthesia was assessed and confirmed at 15 and 30 min. The levels of sensory and motor block on the operative side were evaluated until complete resolution. The rate of unilateral spinal anesthesia at 15 and 30 min was significantly higher in group I (p = 0.015 and 0.028, respectively). Hypotensive events and bradycardia were significantly rarer in group I (p = 0.014 and 0.037, respectively). The density and viscosity of the solution at 5 °C was significantly higher than at 23 °C (p bupivacaine to 5 °C increased the density and viscosity of the solution and the success rate of unilateral spinal anesthesia, and decreased the hemodynamic complication rate.

  13. An Advanced Sodium-Cooled Fast Reactor Core Concept Using Uranium-Free Metallic Fuels for Maximizing TRU Burning Rate

    Directory of Open Access Journals (Sweden)

    Wuseong You

    2017-12-01

    Full Text Available In this paper, we designed and analyzed advanced sodium-cooled fast reactor cores using uranium-free metallic fuels for maximizing burning rate of transuranics (TRU nuclides from PWR spent fuels. It is well known that the removal of fertile nuclides such as 238U from fuels in liquid metal cooled fast reactor leads to the degradation of important safety parameters such as the Doppler coefficient, coolant void worth, and delayed neutron fraction. To resolve the degradation of the Doppler coefficient, we considered adding resonant nuclides to the uranium-free metallic fuels. The analysis results showed that the cores using uranium-free fuels loaded with tungsten instead of uranium have a significantly lower burnup reactivity swing and more negative Doppler coefficients than the core using uranium-free fuels without resonant nuclides. In addition, we considered the use of axially central B4C absorber region and moderator rods to further improve safety parameters such as sodium void worth, burnup reactivity swing, and the Doppler coefficient. The results of the analysis showed that the final design core can consume ~353 kg per cycle and satisfies self-controllability under unprotected accidents. The fuel cycle analysis showed that the PWR–SFR coupling fuel cycle option drastically reduces the amount of waste going to repository and the SFR burner can consume the amount of TRUs discharged from 3.72 PWRs generating the same electricity.

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

    Science.gov (United States)

    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.

  15. A new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling systems

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Zhao, Jianing; Olesen, Bjarne W.

    2015-01-01

    In this paper, a new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling system was proposed and established using the conduction shape factor. Measured data from references were used to validate the proposed model. The results showed...... that the maximum differences between the calculated surface temperature and heat transfer using the proposed model and the measured data were 0.8 ºC and 8.1 W/m2 for radiant floor heating system when average water temperature between 40 ºC and 60 ºC. For the corresponding values were 0.3 ºC and 2.0 W/m2...... for radiant floor cooling systems when average water temperature between 10 ºC and 20 ºC. Numerically simulated data in this study were also used to validate the proposed model. The results showed that the surface temperature and heat transfer of radiant floor calculated by the proposed model agreed very well...

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

    Science.gov (United States)

    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.

  17. Study of the oxidation mechanisms between impurities and surfaces applied to the future gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Duval, A.

    2010-01-01

    Inconel 617, main candidate for the heat exchangers of the gas-cooled next generation of nuclear reactors has been investigated. Two different problems occurring in the cooling system splits the study into two parts. Oxidizing impurities contained in the coolant can cause severe corrosion at 850 C. Radioactive impurities, coming from the fission reaction of the core can, in another hand contaminate the cooling loop and cause radioprotection problem for the maintenance and dismantling operations. Firstly, oxidizing gas partial pressure influence on oxidation of IN 617 at 850 C was investigated varying oxygen and water vapour partial pressure between 1.10 -5 mbar and 200 mbar. Oxide layers were characterized using XPS, SEM, EDX, GD-OES, XRD. Influence of partial pressure on layers structure and composition was determined. Effect of water vapour and partial pressure on growth mechanisms were also investigated. The second part of this study is focused on diffusion of Ag, stable isotope of Ag-110m in IN617 alloy and in the oxide layer forming at its surface at 850 C. Concentration profiles were obtained by GD-OES calibrated analysis. Diffusion coefficient could be obtained from these diffusion profiles: volume diffusion and grain boundary diffusion coefficients for the diffusion in the alloy, and an apparent diffusion coefficient for the diffusion in the oxide, due to the porosity of the structure. (author) [fr

  18. Choice of mode of operations of the thermoelectrical cooling device, ensuring the minimal failure rate

    Directory of Open Access Journals (Sweden)

    Zaikov V. P.

    2008-04-01

    Full Text Available A comparative analysis of TCD reliability has been carried out for different current modes. The paper presents relations allowing to determine the relative value of the operating current at a predetermined temperature difference, which provides the minimum failure rate. The possibility of predicting the reliability of devices at the design stage is shown.

  19. A Two-Phase Cooling Loop for Fission Surface Power Waste Heat Transport, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Current lunar-based Fission Surface Power (FSP) Systems that will support sustained surface outposts consist of a nuclear reactor with power converters, whose waste...

  20. The effects of concentration and heating-cooling rate on rheological properties of Plantago lanceolata seed mucilage.

    Science.gov (United States)

    Hesarinejad, Mohammad Ali; Sami Jokandan, Maryam; Mohammadifar, Mohammad Amin; Koocheki, Arash; Razavi, Seyed Mohammad Ali; Ale, Marcel Tutor; Attar, Farnaz Rezaiyan

    2017-10-17

    In this study, the effect of concentration (0.5, 1, 1.5 and 2%) and heating-cooling rate (1, 5 and 10°Cmin -1 ) on the rheological properties of Plantago lanceolata seed mucilage (PLSM) solutions were investigated. It was observed that the gum dispersions exhibited viscoelastic properties under the given conditions. Mechanical spectra of PLSM were classified as weak gels based on the frequency sweep, complex viscosity (η*) and tan δ results. All variables had significant impacts on the rheological parameters. Chemical and monosaccharide compositions were also determined to provide more structural information. The results revealed that PLSM had high total sugar content (87.35%), and it is likely an arabinoxylomannan-type polysaccharide. Copyright © 2017. Published by Elsevier B.V.

  1. Thermal expansion and cooling rate dependence of transition temperature in ZrTiO4 single crystal

    International Nuclear Information System (INIS)

    Park, Y.

    1998-01-01

    Thermal expansion in ZrTiO 4 single crystal was investigated in the temperature range covering the normal, incommensurate, and commensurate phases. Remarkable change was found at the normal-incommensurate phase transition (T I ) in all thermal expansion coefficients a, b, and c. The spontaneous strains χ as and χ bs along the a and b axes show linear temperature dependence, while the spontaneous strain χ cs along the c axis shows a nonlinear temperature dependence. Small discontinuity along the c direction was observed at the incommensurate-commensurate transition temperature, T c = 845 C. dT I /dP and dT c /dP depend on the cooling rate

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Preliminary Study on Mass Flow Rate in Passive Cooling Experimental Simulation During Transient Using NC-Queen Apparatus

    Directory of Open Access Journals (Sweden)

    M. Juarsa

    2014-12-01

    Full Text Available The research related to thermal management has been significantly inreased, especially for NPP safety. The use of passive cooling systems both during the accident and operation become reliable in the advanced reactor safety systems. Therefore it should be enhanced through experimental studies to investigate heat transfer phenomenon of the heat decay in transient cooling condition.An investigation has been performed through experiment using an NC-Queen apparatusconstructed with rectangular loop. Piping were consisting of tubes of SS316L with diameter, length, and width of 3/4 inch, 2.7 m, and 0.5 m respectively. The height between heater and cooler was 1.4 m. The experiment used initial water temperature at 70oC, 80oC, and 90oC in heater area. Transient temperature was used as experimental data to calculate water mass flow rate. The results showed that the temperature in heater area and cooler area were decreasing of about 90.6% and 95.7% at initial temperatur of 80oC, and of about 71.1% and 59.4% at initial temperature of 70oC. Those results were at higher initial temperature of 90oC compared with the initial temperature of 90oC. The average of water mass flow rate increased 81.03% from initial temperatur of 70oC. It was shown that the averages of removed heat in every second from water due to heat loss and cooler,were 3.51 watts, 5.06 watts and 6.85 watts respectively. The initial condition of heat stored in the water was quite different, but to the cooler heat removal capacity and heat loss was almost the same.

  4. Research on optimization design of conformal cooling channels in hot stamping tool based on response surface methodology and multi-objective optimization

    Directory of Open Access Journals (Sweden)

    He Bin

    2016-01-01

    Full Text Available In order to optimize the layout of the conformal cooling channels in hot stamping tools, a response surface methodology and multi-objective optimization technique are proposed. By means of an Optimal Latin Hypercube experimental design method, a design matrix with 17 factors and 50 levels is generated. Three kinds of design variables, the radius Rad of the cooling channel, the distance H from the channel center to tool work surface and the ratio rat of each channel center, are optimized to determine the layout of cooling channels. The average temperature and temperature deviation of work surface are used to evaluate the cooling performance of hot stamping tools. On the basis of the experimental design results, quadratic response surface models are established to describe the relationship between the design variables and the evaluation objectives. The error analysis is performed to ensure the accuracy of response surface models. Then the layout of the conformal cooling channels is optimized in accordance with a multi-objective optimization method to find the Pareto optimal frontier which consists of some optimal combinations of design variables that can lead to an acceptable cooling performance.

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

    Science.gov (United States)

    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

  6. Incorporation of velocity-dependent restitution coefficient and particle surface friction into kinetic theory for modeling granular flow cooling.

    Science.gov (United States)

    Duan, Yifei; Feng, Zhi-Gang

    2017-12-01

    Kinetic theory (KT) has been successfully used to model rapid granular flows in which particle interactions are frictionless and near elastic. However, it fails when particle interactions become frictional and inelastic. For example, the KT is not able to accurately predict the free cooling process of a vibrated granular medium that consists of inelastic frictional particles under microgravity. The main reason that the classical KT fails to model these flows is due to its inability to account for the particle surface friction and its inelastic behavior, which are the two most important factors that need be considered in modeling collisional granular flows. In this study, we have modified the KT model that is able to incorporate these two factors. The inelasticity of a particle is considered by establishing a velocity-dependent expression for the restitution coefficient based on many experimental studies found in the literature, and the particle friction effect is included by using a tangential restitution coefficient that is related to the particle friction coefficient. Theoretical predictions of the free cooling process by the classical KT and the improved KT are compared with the experimental results from a study conducted on an airplane undergoing parabolic flights without the influence of gravity [Y. Grasselli, G. Bossis, and G. Goutallier, Europhys. Lett. 86, 60007 (2009)10.1209/0295-5075/86/60007]. Our results show that both the velocity-dependent restitution coefficient and the particle surface friction are important in predicting the free cooling process of granular flows; the modified KT model that integrates these two factors is able to improve the simulation results and leads to better agreement with the experimental results.

  7. Incorporation of velocity-dependent restitution coefficient and particle surface friction into kinetic theory for modeling granular flow cooling

    Science.gov (United States)

    Duan, Yifei; Feng, Zhi-Gang

    2017-12-01

    Kinetic theory (KT) has been successfully used to model rapid granular flows in which particle interactions are frictionless and near elastic. However, it fails when particle interactions become frictional and inelastic. For example, the KT is not able to accurately predict the free cooling process of a vibrated granular medium that consists of inelastic frictional particles under microgravity. The main reason that the classical KT fails to model these flows is due to its inability to account for the particle surface friction and its inelastic behavior, which are the two most important factors that need be considered in modeling collisional granular flows. In this study, we have modified the KT model that is able to incorporate these two factors. The inelasticity of a particle is considered by establishing a velocity-dependent expression for the restitution coefficient based on many experimental studies found in the literature, and the particle friction effect is included by using a tangential restitution coefficient that is related to the particle friction coefficient. Theoretical predictions of the free cooling process by the classical KT and the improved KT are compared with the experimental results from a study conducted on an airplane undergoing parabolic flights without the influence of gravity [Y. Grasselli, G. Bossis, and G. Goutallier, Europhys. Lett. 86, 60007 (2009), 10.1209/0295-5075/86/60007]. Our results show that both the velocity-dependent restitution coefficient and the particle surface friction are important in predicting the free cooling process of granular flows; the modified KT model that integrates these two factors is able to improve the simulation results and leads to better agreement with the experimental results.

  8. The effect of cooling rate from the γ-phase on the strain-rate sensitivity of a uranium 2 sup(w)/o molybdenum alloy

    International Nuclear Information System (INIS)

    Boyd, G.A.C.; Harding, J.

    1983-01-01

    Tensile tests have been performed at strain rates from 10 -4 to about 2000/s and temperatures from -150 deg C to +250 deg C on a uranium 2 w/o molybdenum alloy which had been aged for 2 hours at 500 deg C after a fast gas cool from the γ-phase at a controlled rate of 40 deg C/minute. The results are compared with those for standard as-extruded material which had received the same aging treatment. Stress-strain curves are presented and the effect of strain rate and temperature on the flow stress, the ultimate tensile stress and the elongation to fracture is determined. A thorough structural characterisation of the specimen materials, using X-ray analysis and scanning and transmission electron microscopy, allows the different mechanical responses to be related to the corresponding microstructural state of the material. Flow stress data at different temperatures and strain rates are analysed in terms of the theory of thermally-activated flow and estimates made of the various activation parameters. (author)

  9. Experimental study on supersonic film cooling on the surface of a blunt body in hypersonic flow

    International Nuclear Information System (INIS)

    Fu Jia; Yi Shi-He; Wang Xiao-Hu; He Lin; Ge Yong

    2014-01-01

    The experimental study focuses on the heat flux on a double cone blunt body in the presence of tangential-slot supersonic injection into hypersonic flow. The tests are conducted in a contoured axisymmetric nozzle with Mach numbers of 7.3 and 8.1, and the total temperature is about 900 K. The injection Mach number is 3.2, and total temperature is 300 K. A constant voltage circuit is developed to supply the temperature detectors instead of the normally used constant current circuit. The schlieren photographs are presented additionally to visualize the flow and help analyze the pressure relationship between the cooling flow and the main flow. The dependence of the film-cooling effectiveness on flow parameters, i.e. the blow ratio, the convective Mach number, and the attack angle, is determined. A semi-empirical formula is tested by the present data, and is improved for a better correlation. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. Evaluation of cooling performance of impinging jet array over various dimpled surfaces

    Science.gov (United States)

    Kim, Sun-Min; Kim, Kwang-Yong

    2016-04-01

    Various configurations of an impinging jet-dimple array cooling system were evaluated in terms of their heat transfer and pressure drop performances. The steady incompressible laminar flow and heat transfer in the cooling system were analyzed using three-dimensional Navier-Stokes equations. The obtained numerical results were validated by a comparison with experimental data for the local Nusselt number distribution. The area-averaged Nusselt number on the projected area and the pressure drop through the system were selected as the performance parameters. Among the four tested configurations—inline concave, staggered concave, inline convex, and staggered convex—the staggered convex impinging jet-dimple array showed the best heat transfer performance whereas the staggered-concave configuration showed the lowest pressure drop. A parametric study with two geometric variables, i.e., the height of dimple and the diameter of dimple, was also conducted for the staggered-convex impinging jet-dimple array. As a result, the best heat transfer and pressure drop performances were achieved when the ratio of the height of dimple to the diameter of jet was 0.8. And, the increase in the ratio of the diameter of dimple to the diameter of jet yielded monotonous increase in the heat transfer performance.

  11. Clad failures detection on sodium-cooled fast reactors by high count rate gamma spectroscopy

    International Nuclear Information System (INIS)

    Rohee, Emmanuel

    2016-01-01

    The question of clad failures detection, through the monitoring of potentially released fission products in the primary sodium, is of utmost importance for SFR type generation IV reactors, and in particular for the future ASTRID industrial demonstrator. This thesis aims to propose ways to significantly improve the nuclear instrumentation dedicated to clad failures detection. A first study regarding the signal-to-noise ratio of the existing instrumentation, which is based on Delayed Neutron Detection (DND), is proposed. The experience feedback, as well as the Monte Carlo simulations, shows a disturbance of the useful neutron signal by photoneutrons produced in the polyethylene. A material replacement solution based on the use of graphite is proposed, and its performances are evaluated by Monte Carlo simulations and experiments. The second lead followed, technologically more ambitious, consists in enriching the existing instrumentation by introducing an innovative method, based on high count rate gamma spectroscopy on the primary sodium. In addition to bringing redundancy to the current instrumentation, such a spectroscopy would permit to enrich the clad failure diagnosis with an earlier and more complete measure (broader range of accessible fission products). First, a feasibility study is carried out using Monte Carlo simulations, by modeling a measurement station and simulating the HPGe detector response. Minimal detectable activities are calculated for the fission products of interest, and compared with results from simulations of release following a clad failure scenario. In a second stage, high count rate gamma spectroscopy using the ADONIS spectrometry system developed by CEA LIST was tested and validated in a real environment, by installing a measuring station on the ISABELLE 1 fuel pin irradiation loop at the OSIRIS reactor. Several irradiations have been monitored in this thesis, two of which allowed to follow a clad failure process using this approach

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Effect of cooling rate on the microstructure and luminescence properties of Sr2MgSi2O7:Eu2+,Dy3+materials.

    Science.gov (United States)

    Hai, Ou; Jiang, Hongyi; Zhang, Qiang; Ren, Qiang; Wu, Xiulan; Hu, Jieliang

    2017-12-01

    Sr 2 MgSi 2 O 7 :Eu 2+ ,Dy 3+ long afterglow materials were prepared by a high-temperature solid-state reaction method with different cooling rates. The cooling rate had a slight effect on X-ray diffraction patterns and photoluminescence performance, but significantly modified the grain boundaries and long afterglow properties of the Sr 2 MgSi 2 O 7 :Eu 2+ ,Dy 3+ materials. When the cooling rate was 1°C/min, grains remained intact with clear grain boundaries. As the cooling rate increased from 1°C/min to 5°C/min, some grain boundaries became indistinguishable. The afterglow properties were optimized, presenting best performance at the cooling rate of 3°C/min. The trap state was investigated and illustrated through thermoluminescence curves. The depths of the traps of all the samples were unchanged, whereas densities changed to a large extent, leading to different afterglow properties. The retrapping process is discussed based on the afterglow curves. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Rate law analysis of water oxidation on a hematite surface.

    Science.gov (United States)

    Le Formal, Florian; Pastor, Ernest; Tilley, S David; Mesa, Camilo A; Pendlebury, Stephanie R; Grätzel, Michael; Durrant, James R

    2015-05-27

    Water oxidation is a key chemical reaction, central to both biological photosynthesis and artificial solar fuel synthesis strategies. Despite recent progress on the structure of the natural catalytic site, and on inorganic catalyst function, determining the mechanistic details of this multiredox reaction remains a significant challenge. We report herein a rate law analysis of the order of water oxidation as a function of surface hole density on a hematite photoanode employing photoinduced absorption spectroscopy. Our study reveals a transition from a slow, first order reaction at low accumulated hole density to a faster, third order mechanism once the surface hole density is sufficient to enable the oxidation of nearest neighbor metal atoms. This study thus provides direct evidence for the multihole catalysis of water oxidation by hematite, and demonstrates the hole accumulation level required to achieve this, leading to key insights both for reaction mechanism and strategies to enhance function.

  16. Effects of cooling methods on the occurrence of sulfur in the low-titanium slag

    Science.gov (United States)

    Wang, Baohua; Zhang, Mingbo; Gong, Yongyu; Huang, Shiping; Qiu, Shengtao; Zhu, Rong

    2018-01-01

    The distribution of sulfur existence in the mineral phase and occurrence in the low-titanium slag with different cooling methods (water cooling, air cooling, crucible cooling, and furnace cooling) were studied by XRD, EPMA and XPS. The results show that with the cooling rate decrease, the distribution of S changes from clustering dots to large sheet or surface, and the occurrence of S in the mineral phase transfers gradually from the vitreous, perovskite, merwinite and the intertwined phase of some mineral phases to the gehlenite. During the transfer, the velocity decreases with the increasing of the cooling rate. The S in the water cooling slag only exists in the form of SO32- and SO42-, while the occurrences of S in the air cooling slag, crucible cooling slag, and furnace cooling slag are S2-, SO32- and SO42-.

  17. Contribution to the study on the flow rate adjustment for gas cooled power reactors (1964)

    International Nuclear Information System (INIS)

    Milliot, B.

    1961-06-01

    1. This original study firstly defines the problem of the adjustment of the coolant flow rate in a reactor channel as a function of the corresponding heat transfer equations and of the local and temporal neutron flux. The necessity of such an adjustment is pointed out and the modifying parameters are studied. An adjustment study using the envelope of the possible flux curves is developed. A short study on the technology and the economical advantage of this adjustment is presented. Some measurements, made on G-1 and G-2, show the precision one can obtain from adjustment apparatus itself as well as from the complete reactor adjustment system. 2. Evolution of nuclear properties of fuel in an heterogeneous thermal reactor. In the first port of this paper, the phenomena of fuel evolution have been mainly pointed out. Now a bibliographical study more qualitatively than quantitatively has been done. This survey specifies the present theories and relates to a real effective cross section and also yields to the bases of such a nuclear calculation. (author) [fr

  18. Cooling water distribution system

    Science.gov (United States)

    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.

  19. Cooled-Spool Piston Compressor

    Science.gov (United States)

    Morris, Brian G.

    1994-01-01

    Proposed cooled-spool piston compressor driven by hydraulic power and features internal cooling of piston by flowing hydraulic fluid to limit temperature of compressed gas. Provides sufficient cooling for higher compression ratios or reactive gases. Unlike conventional piston compressors, all parts of compressed gas lie at all times within relatively short distance of cooled surface so that gas cooled more effectively.

  20. Effects of Cooling Rate and Aging Temperature of CuCrZr Alloys for Fabrication of ITER First Wall

    International Nuclear Information System (INIS)

    Lee, Jung-Suk; Park, Jeong-Yong; Choi, Byung-Kwon; Jeong, Yong-Hwan

    2007-01-01

    The first wall of the International Thermonuclear Experimental Reactor (ITER) is multilayer components consisting of plasma facing armor materials, heat sink materials and structural materials. The joining of three different materials has been critical issue in the fabrication of ITER first wall. For a successful fabrication of such complex components, the diffusion welding method is favored. Hot isostatic pressure (HIP) is one of the promising diffusion welding methods that allows uniform distribution of the pressure and good dimensional tolerances. The precipitation strengthened CuCrZr alloys are being considered as potential heat sink material for the shielding blanket of ITER first wall, due to its high strength and high thermal conductivity at a high temperature. However, the mechanical properties of CuCrZr are sensitive to the thermal history. The first HIP process for the joining of CuCrZr/stainless steel (SS) is carried out at high temperature of 1050 .deg. C for 2hrs. However, for security reasons such as a high pressure of the HIP vessel, the HIP quenching operation is not possible. Therefore, a supplementary solution annealing procedure has been inserted into the heat treatment process just after CuCrZr/SS HIP joining treatment in order to have a sufficient fast cooling of the CuCrZr. Fast cooling is needed in order to avoid the formation of too large precipitates, and so, a CuCrZr with good material properties. A subsequent HIP process to join the Be tiles to the CuCrZr is also needed in order to age-harden the CuCrZr. Although a increase of the HIP temperature is desirable for a improvement of a HIP joining strength, the maximum temperature to be applicable to the Be/CuCrZr joint HIP procedure is limited by an overaging of CuCrZr. In this study, the effect of the cooling rate and aging treatment on the mechanical properties of CuCrZr is investigated to optimize the HIP joining conditions

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

    Science.gov (United States)

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

    2010-01-01

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

  2. Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

    Directory of Open Access Journals (Sweden)

    Phil Ligrani

    2012-01-01

    Full Text Available The influences of a variety of different physical phenomena are described as they affect the aerodynamic performance of turbine airfoils in compressible, high-speed flows with either subsonic or transonic Mach number distributions. The presented experimental and numerically predicted results are from a series of investigations which have taken place over the past 32 years. Considered are (i symmetric airfoils with no film cooling, (ii symmetric airfoils with film cooling, (iii cambered vanes with no film cooling, and (iv cambered vanes with film cooling. When no film cooling is employed on the symmetric airfoils and cambered vanes, experimentally measured and numerically predicted variations of freestream turbulence intensity, surface roughness, exit Mach number, and airfoil camber are considered as they influence local and integrated total pressure losses, deficits of local kinetic energy, Mach number deficits, area-averaged loss coefficients, mass-averaged total pressure loss coefficients, omega loss coefficients, second law loss parameters, and distributions of integrated aerodynamic loss. Similar quantities are measured, and similar parameters are considered when film-cooling is employed on airfoil suction surfaces, along with film cooling density ratio, blowing ratio, Mach number ratio, hole orientation, hole shape, and number of rows of holes.

  3. Analysis of transient and hysteresis behavior of cross-flow heat exchangers under variable fluid mass flow rate for data center cooling applications

    International Nuclear Information System (INIS)

    Gao, Tianyi; Murray, Bruce; Sammakia, Bahgat

    2015-01-01

    Effective thermal management of data centers is an important aspect of reducing the energy required for the reliable operation of data processing and communications equipment. Liquid and hybrid (air/liquid) cooling approaches are becoming more widely used in today's large and complex data center facilities. Examples of these approaches include rear door heat exchangers, in-row and overhead coolers and direct liquid cooled servers. Heat exchangers are primary components of liquid and hybrid cooling systems, and the effectiveness of a heat exchanger strongly influences the thermal performance of a cooling system. Characterizing and modeling the dynamic behavior of heat exchangers is important for the design of cooling systems, especially for control strategies to improve energy efficiency. In this study, a dynamic thermal model is solved numerically in order to predict the transient response of an unmixed–unmixed crossflow heat exchanger, of the type that is widely used in data center cooling equipment. The transient response to step and ramp changes in the mass flow rate of both the hot and cold fluid is investigated. Five model parameters are varied over specific ranges to characterize the transient performance. The parameter range investigated is based on available heat exchanger data. The thermal response to the magnitude, time period and initial and final conditions of the transient input functions is studied in detail. Also, the hysteresis associated with the fluid mass flow rate variation is investigated. The modeling results and performance data are used to analyze specific dynamic performance of heat exchangers used in practical data center cooling applications. - Highlights: • The transient performance of a crossflow heat exchanger was modeled and studied. • This study provides design information for data center thermal management. • The time constant metric was used to study the impacts of many variable inputs. • The hysteresis behavior

  4. Turbine component having surface cooling channels and method of forming same

    Science.gov (United States)

    Miranda, Carlos Miguel; Trimmer, Andrew Lee; Kottilingam, Srikanth Chandrudu

    2017-09-05

    A component for a turbine engine includes a substrate that includes a first surface, and an insert coupled to the substrate proximate the substrate first surface. The component also includes a channel. The channel is defined by a first channel wall formed in the substrate and a second channel wall formed by at least one coating disposed on the substrate first surface. The component further includes an inlet opening defined in flow communication with the channel. The inlet opening is defined by a first inlet wall formed in the substrate and a second inlet wall defined by the insert.

  5. Diurnal and Seasonal Variation of Surface Urban Cool and Heat Islands in the Semi-Arid City of Erbil, Iraq

    Directory of Open Access Journals (Sweden)

    Azad Rasul

    2016-09-01

    Full Text Available The influence of land surface temperature (LST makes the near-surface layer of the troposphere a key driver of urban climate. This paper assesses the temporal formation of the daytime Surface Urban Cool Island (SUCI and night-time Surface Urban Heat Island (SUHI effect in Erbil, Iraq, situated in a semi-arid climate region. LST retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS Aqua and Terra and MODIS Normalized Difference Vegetation Index (NDVI from January 2003 to December 2014 are analysed. The relationships of LST with NDVI and the Normalized Multi-band Drought Index (NMDI are investigated in order to assess the influence of vegetation and moisture on the observed patterns of LST and the SUCI/SUHI. The results indicate that during the daytime, in summer, autumn and winter, densely built-up areas had lower LST acting as a SUCI compared to the non-urbanised area around the city. In contrast, at night-time, Erbil experienced higher LST and demonstrated a significant SUHI effect. The relationship between LST and NDVI is affected by seasonality and is strongly inverted during spring (r2 = 0.73; p < 0.01. Contrary to previous studies of semi-arid cities, a SUCI was detected, not only in the morning, but also during the afternoon.

  6. Evaluation of Tool Path Strategy and Cooling Condition Effects on the Cutting Force and Surface Quality in Micromilling Operations

    Directory of Open Access Journals (Sweden)

    Ugur Koklu

    2017-10-01

    Full Text Available Compared to milling on a macro scale, the micromilling process has several cumbersome points that need to be addressed. Rapid tool wear and fracture, severe burr formation, and poor surface quality are the major problems encountered in the micromilling process. This study aimed to reveal the effect of cutting path strategies on the cutting force and surface quality in the micromilling of a pocket. The hatch zigzag tool path strategy and the contour climb tool path strategy under different cooling conditions (e.g., dry, air blow, and flood coolant at fixed cutting parameters. The micromilling tests revealed that better results were obtained with the use of the contour tool path strategy in terms of cutting forces (by up to ~43% compared to the dry condition and surface quality (by up to ~44% compared to the air blow condition when compared to the hatch tool path strategy. In addition, the flood coolant reduces the cutting temperature and eliminates chips to significantly enhance the quality of the micro milled surface.

  7. STEADY-STATE HEAT REJECTION RATES FOR A COAXIAL BOREHOLE HEAT EXCHANGER DURING PASSIVE AND ACTIVE COOLING DETERMINED WITH THE NOVEL STEP THERMAL RESPONSE TEST METHOD

    Directory of Open Access Journals (Sweden)

    Marija Macenić

    2018-01-01

    Full Text Available At three locations in Zagreb, classical and extended thermal response test (TRT was conducted on installed coaxial heat exchangers. With classic TR test, thermogeological properties of the ground and thermal resistance of the borehole were determined at each location. It is seen that thermal conductivity of the ground varies, due to difference in geological profile of the sites. In addition, experimental research of steady-state thermal response step test (SSTRST was carried out to determine heat rejection rates for passive and active cooling in steady state regime. Results showed that heat rejection rate is only between 8-11 W/m, which indicates that coaxial system is not suitable for passive cooling demands. Furthermore, the heat pump in passive cooling mode uses additional plate heat exchanger where there is additional temperature drop of working fluid by approximately 1,5 °C. Therefore, steady-state rejection rate for passive cooling is even lower for a real case project. Coaxial heat exchanger should be always designed for an active cooling regime with an operation of a heat pump compressor in a classical vapour compression refrigeration cycle.

  8. Effects of Cooling Fluid Flow Rate on the Critical Heat Flux and Flow Stability in the Plate Fuel Type 2 MW TRIGA Reactor

    Directory of Open Access Journals (Sweden)

    H. P. Rahardjo

    2017-12-01

    Full Text Available The conversion program of the 2 MW TRIGA reactor in Bandung consisted of the replacement of cylindrical fuel (produced by General Atomic with plate fuel (produced by BATAN. The replacement led into the change of core cooling process from upward natural convection type to downward forced convection type, and resulted in different thermohydraulic safety criteria, such as critical heat flux (CHF limit, boiling limit, and cooling fluid flow stability. In this paper, a thermohydraulic safety analysis of the converted TRIGA reactor is presented by considering the Dynamic Nucleate Boiling Ratio (DNBR criterion, Onset Nucleate Boiling Ratio (ONBR limit, and cooling fluid flow stability at various cooling fluid flow rate.The numerical analyses were performed using the HEATHYD program on the hottest channels of reactor core.The combination of heat transfer and fluid flow analysis were conducted for reactor operation at 2 MW with 20 fuel element bundles and four control rod bundles. Incoming fluid flow to the cooling channel was fixed at 44.5 °C temperature and 1.9970 bar pressure, and its flow rate was varied from 1.25 to 3.5 m3/h. By inputting these values, as well as the total power of fuel elements per bundle, the wall temperature distribution of the plate fuel element, cooling fluid temperature distribution, and pressure losses in the channels were obtained for the analysis of CHF limit, boiling limit, and flow stability. It was shown that no boiling occurred for the cooling fluid flow rate range of 2.4 to 3.5 m3/h, and even at the cooling fluid flow rate of 1.25 m3/h where some bubbles occurred, the DNBR was higher than the critical limit (more than 23 while the flow stability criterion in some channels were slightly less than 1 (unstable. At the cooling fluid flow rate of 1.4 m3/h, however, the flow became stable in all channel. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants.

    Science.gov (United States)

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-10-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes-conversion and deposition coatings-while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are

  9. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

    International Nuclear Information System (INIS)

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-01-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches

  10. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

    Science.gov (United States)

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-01-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches

  11. Conjugate Heat Transfer Study at Interior Surface of NGV Leading Edge with Combined Shower Head and Impingement Cooling

    Directory of Open Access Journals (Sweden)

    Arun Kumar Pujari

    2014-01-01

    Full Text Available A computational study on conjugate heat transfer is carried out to present the behavior of nondimensional temperature and heat transfer coefficient of a Nozzle Guide Vane (NGV leading edge. Reynolds number of both mainstream flow and coolant impinging jets are varied. The NGV has five rows of film cooling holes arranged in shower head manner and four rows of impingement holes arranged in staggered manner. The results are presented by considering materials of different thermal conductivity. The results show that the mainstream flow affects the temperature distribution on the interior side of the vane leading edge for high conductivity material whereas it has negligible effects for low conductivity material. The effect of changing blowing ratio on internal heat transfer coefficient and internal surface temperature is also presented.

  12. Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions

    Science.gov (United States)

    Kaynak, Y.; Huang, B.; Karaca, H. E.; Jawahir, I. S.

    2017-07-01

    This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish ( A f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

  13. Land surface phenologies and seasonalities using cool earthlight in mid-latitude croplands

    International Nuclear Information System (INIS)

    Alemu, W G; Henebry, G M

    2013-01-01

    Phenology deals with timing of biotic phenomena and seasonality concerns temporal patterns of abiotic variables. Studies of land surface phenology (LSP) and land surface seasonality (LSS) have long been limited to visible to near infrared (VNIR) wavelengths, despite degradation by atmospheric effects and solar illumination constraints. Enhanced land surface parameters derived from passive microwave data enable improved temporal monitoring of agricultural land surface dynamics compared to the vegetation index data available from VNIR data. LSPs and LSSs in grain growing regions of the Volga River Basin of Russia and the spring wheat belts of the USA and Canada were characterized using AMSR-E enhanced land surface parameters for the period from April through October for 2003 through 2010. Growing degree-days (GDDs) were calculated from AMSR-E air temperature retrievals using both ascending and descending passes with a base of 0 ° C and then accumulated (AGDD) with an annual restart each 1 April. Tracking the AMSR-E parameters as a function of AGDD revealed the expected seasonal pattern of thermal limitation in mid-latitude croplands. Vegetation optical depth (VOD), a microwave analog of a vegetation index, was modeled as a function of AGDD with the resulting fitted convex quadratic models yielding both high coefficients of determination (r 2 > 0.90) and phenometrics that could characterize cropland differences between the Russian and North American sites. The AMSR-E data were also able to capture the effects of the 2010 heat wave that devastated grain production in European Russia. These results showed the potential of AMSR-E in monitoring and modeling cropland dynamics. (letter)

  14. Gender-specific cold responses induce a similar body-cooling rate but different neuroendocrine and immune responses.

    Science.gov (United States)

    Solianik, Rima; Skurvydas, Albertas; Vitkauskienė, Astra; Brazaitis, Marius

    2014-08-01

    This study investigated whether there are any gender differences in body-heating strategies during cold stress and whether the immune and neuroendocrine responses to physiological stress differ between men and women. Thirty-two participants (18 men and 14 women) were exposed to acute cold stress by immersion to the manubrium level in 14 °C water. The cold stress continued until rectal temperature (TRE) reached 35.5 °C or for a maximum of 170 min. The responses to cold stress of various indicators of body temperature, insulation, metabolism, shivering, stress, and endocrine and immune function were compared between men and women. During cold stress, TRE and muscle and mean skin temperatures decreased in all subjects (Pcold strain did not differ between men and women, but men exhibited larger changes in the indicators of neuroendocrine (epinephrine level) and in immune (tumor necrosis factor-α level) responses (both Pcold stress, whereas women exhibited a greater insulative response. Despite the similar experience of cold strain in men and women, the neuroendocrine and immune responses were larger in men. Contrary to our expectations, the cooling rate was similar in men and women. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    Science.gov (United States)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

  16. Study of cooling effectiveness for an integrated cooling turbine blade

    OpenAIRE

    Matsushita, Masahiro; Yamane, Takashi; Mimura, Fujio; Fukuyama, Yoshitaka; 松下 政裕; 山根 敬; 三村 富嗣雄; 福山 佳孝

    2007-01-01

    Experimental study of film cooling, impingement cooling and integrated cooling were carried out with the aim of applying them to turbine cooling. The experiments were conducted with 673 K hot gas flow and room temperature cooling air. Test plate surface temperature distributions were measured with an infrared camera. This report presents fundamental research data on cooling performance of the test plates for the validation of numerical simulation. Moreover, simplify heat transfer calculations...

  17. The production rate of cosmogenic deuterium at the Moon's surface

    Science.gov (United States)

    Füri, Evelyn; Deloule, Etienne; Trappitsch, Reto

    2017-09-01

    The hydrogen (D/H) isotope ratio is a key tracer for the source of planetary water. However, secondary processes such as solar wind implantation and cosmic ray induced spallation reactions have modified the primordial D/H signature of 'water' in all rocks and soils recovered on the Moon. Here, we re-evaluate the production rate of cosmogenic deuterium (D) at the Moon's surface through ion microprobe analyses of hydrogen isotopes in olivines from eight Apollo 12 and 15 mare basalts. These in situ measurements are complemented by CO2 laser extraction-static mass spectrometry analyses of cosmogenic noble gas nuclides (3He, 21Ne, 38Ar). Cosmic ray exposure (CRE) ages of the mare basalts, derived from their cosmogenic 21Ne content, range from 60 to 422 Ma. These CRE ages are 35% higher, on average, than the published values for the same samples. The amount of D detected in the olivines increases linearly with increasing CRE ages, consistent with a production rate of (2.17 ± 0.11) ×10-12 mol(g rock)-1 Ma-1. This value is more than twice as high as previous estimates for the production of D by galactic cosmic rays, indicating that for water-poor lunar samples, i.e., samples with water concentrations ≤50 ppm, corrected D/H ratios have been severely overestimated.

  18. Cooling our communities: A guidebook on tree planting and light-colored surfacing

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, H.; Davis, S.; Huang, J. (eds.) (Lawrence Berkeley Lab., CA (United States)); Dorsano, S. (ed.) (The Bruce Co., (United States)); Winnett, S. (ed.) (Environmental Protection Agency, Washington, DC (United States). Climate Change Div.)

    1992-01-01

    This book is a practical guide that presents the current state of knowledge on potential environmental and economic benefits of strategic landscaping and altering surface colors in our communities. The guidebook, reviews the causes, magnitude, and impacts of increased urban warming, then focuses on actions by citizens and communities that can be undertaken to improve the quality of our homes and towns in cost-effective ways.

  19. Overall Effectiveness Measurement at Engine Temperatures with Reactive Film Cooling and Surface Curvature

    Science.gov (United States)

    2015-03-26

    baseline case. For the baseline case, Tinf = 1829 K, Tc = 625 K, U∞ = 49.4 m/s, Uc = 16 m/s, and M = 0.946. All the cases were performed for a fan...backside surface with a thin Inconel strap which has been resistance welded across the thermocouple’s tip where the bead would be located. In other words

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

    Science.gov (United States)

    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.

  2. Liquid-liquid phase separation and solidification behavior of Al55Bi36Cu9 monotectic alloy with different cooling rates

    Science.gov (United States)

    Bo, Lin; Li, Shanshan; Wang, Lin; Wu, Di; Zuo, Min; Zhao, Degang

    2018-03-01

    The cooling rate has a significant effect on the solidification behavior and microstructure of monotectic alloy. In this study, different cooling rate was designed through casting in the copper mold with different bore diameters. The effects of different cooling rate on the solidification behavior of Al55Bi36Cu9 (at.%) immiscible alloy have been investigated. The liquid-liquid phase separation of Al55Bi36Cu9 immiscible alloy melt was investigated by resistivity test. The solidification microstructure and phase analysis of Al55Bi36Cu9 immiscible alloy were performed by the SEM and XRD, respectively. The results showed that the liquid-liquid phase separation occurred in the solidification of Al55Bi36Cu9 monotectic melt from 917 °C to 653 °C. The monotectic temperature, liquid phase separation temperature and immiscibility zone of Al55Bi36Cu9 monotectic alloy was lower than those of Al-Bi binary monotectic alloy. The solidification morphology of Al55Bi36Cu9 monotectic alloy was very sensitive to the cooling rate. The Al/Bi core-shell structure formed when Al55Bi36Cu9 melt was cast in the copper mold with a 8 mm bore diameter.

  3. Efficient ground-state cooling of an ion in a large room-temperature linear Paul trap with a sub-Hertz heating rate

    DEFF Research Database (Denmark)

    Poulsen, Gregers; Miroshnychenko, Yevhen; Drewsen, Michael

    2012-01-01

    We demonstrate efficient resolved sideband laser cooling (99±1% ground-state population) of a single 40Ca+ ion in a large linear Paul trap (electrode spacing of 7 mm) operated at an rf drive frequency of just 3.7 MHz. For ion oscillation frequencies in the range 280–585 kHz, heating rates below...

  4. Simulation of surface dynamics during dissolution as a function of the surface orientation: Implications for non-constant dissolution rates

    Science.gov (United States)

    Godinho, J. R. A.; Piazolo, S.; Evans, L.

    2014-12-01

    An important problem in geochemistry is the understanding of how changes occurring on a surface during dissolution affect the variability of measured dissolution rates. In this study a new approach to study the effect of surface dynamics on dissolution rates is tested by coupling experimental data with a numerical model that simulates the retreat of surface profiles during dissolution. We present specific results from the simulation of dissolution of fluorite surfaces. The equations that determine the retreat of a surface are based on experimentally obtained equations that relate the retreat rate of a surface to a single variable, the crystallographic orientation of the surface. Our results show that depending on the starting orientation, different types of topography are developed, similar to those observed experimentally. During the initial dissolution phase, changes of topography are rapid and associated with fast dissolution rates. The progressively slower dissolution rates are coupled with the development of surface segments with orientations that dissolve at a slower rate. Consequently, the overall retreat rate of a profile decreases during the simulation, and tends to a near-constant value. The results show a close relationship between dissolution rates, surface orientation and surface dynamics, which suggests that the dissolution rate of a specific mineral phase is not constant but varies with dissolution time and surface structure. This variability needs to be considered in the evaluation of experimentally derived dissolution rates, future dissolution experiments, and predictive kinetic models of dissolution.

  5. Effects of content and surface hydrophobic modification of BaTiO3 on the cooling properties of ASA (acrylonitrile-styrene-acrylate copolymer)

    Science.gov (United States)

    Xiang, Bo; Zhang, Jun

    2018-01-01

    For the field of cool material, barium titanate (BaTiO3, BT) is still a new member that needs to be further studied. Herein, the effects of both content and surface hydrophobic modification of BT on the cooling properties of acrylonitrile-styrene-acrylate copolymer (ASA) were detailedly investigated, aiming to fabricate composited cool material. Butyl acrylate (BA) was employed to convert the surface of BT from hydrophilic to hydrophobic. The addition of unmodified BT could significantly improve the solar reflectance of ASA, especially when the addition amount is 3 vol%, the near infrared (NIR) reflectance increased from 22.02 to 72.60%. However, serious agglomeration occurred when the addition amount increased to 5 vol% and therefore led to a relatively smaller increase in solar reflectance and an obvious decline in impact strength. After surface hydrophobic modification, the modified BT (M-BT) presented better dispersibility in ASA matrix, which contributed to the improvement of both solar reflectance and impact strength. In addition, the temperature test provided a more sufficient and intuitive way to evaluate the cooling effect of the composited cool materials, and a significant decrease (over 10 °C) could be achieved in the temperature test when M-BT particles were introduced.

  6. Modeled Oceanic Response and Sea Surface Cooling to Typhoon Kai-Tak

    Directory of Open Access Journals (Sweden)

    Yu-Heng Tseng

    2010-01-01

    Full Text Available An ocean response to typhoon Kai-Tak is simulated using an accurate fourth-order, basin-scale ocean model. The surface winds of typhoon Kai-Tak were obtained from QuikSCAT satellite images blended with the ECMWF wind fields. An intense nonlinear mesoscale eddy is generated in the northeast South China Sea (SCS with a Rossby number of O(1 and on a 50 - 100 km horizontal scale. Inertial oscillation is clearly observed. Advection dominates as a strong wind shear drives the mixed layer flows outward, away from the typhoon center, thus forcing upwelling from deep levels with a high upwelling velocity (> 30 m day-1. A drop in sea surface temperature (SST of more than 9°C is found in both observation and simulation. We attribute this significant SST drop to the influence of the slow moving typhoon, initial stratification and bathymetry-induced upwelling in the northeast of the SCS where the typhoon hovered.

  7. Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Cr-Doped GdAlO3 Phosphor Thermography

    Science.gov (United States)

    Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

    2016-01-01

    It has been recently shown that the high luminescence intensity from a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor enables non-rastered full-field temperature mapping of thermal barrier coating (TBC) surfaces to temperatures above 1000C. In this presentation, temperature mapping by Cr:GdAlO3 based phosphor thermometry of air film-cooled TBC-coated surfaces is demonstrated for both scaled-up cooling hole geometries as well as for actual components in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

  8. Beam cooling

    OpenAIRE

    Danared, H

    2006-01-01

    Beam cooling is the technique of reducing the momentum spread and increasing the phase-space density of stored particle beams. This paper gives an introduction to beam cooling and Liouville’s theorem, and then it describes the three methods of active beam cooling that have been proven to work so far, namely electron cooling, stochastic cooling, and laser cooling. Ionization cooling is also mentioned briefly.

  9. Hybrid Cooling System for Industrial Application | Ezekwe | Nigerian ...

    African Journals Online (AJOL)

    The unit utilizes water-in-air stream to cool molds in glass and plastic forming processes. The rate of heat transfer between the mold surface and the two ... The system also reduced the level of noise due to air blast at the press by limiting the use of compressed air. This cooling unit could also be used in iron and steel ...

  10. Isopleths of surface air concentration and surface air kerma rate due to a radioactive cloud released from a stack (3)

    International Nuclear Information System (INIS)

    Tachibana, Haruo; Kikuchi, Masamitsu; Sekita, Tsutomu; Yamaguchi, Takenori

    2004-06-01

    This report is a revised edition of 'Isopleths of Surface Air Concentration and Surface Air Absorbed Dose Rate due to a Radioactive Cloud Released from a Stack(II) '(JAERI-M 90-206) and based on the revised Nuclear Safety Guidelines reflected the ICRP1990 Recommendation. Characteristics of this report are the use of Air Karma Rate (Gy/h) instead of Air Absorbed Dose Rate (Gy/h), and the record of isopleths of surface air concentration and surface air karma rate on CD-ROM. These recorded data on CD-ROM can be printed out on paper and/or pasted on digital map by personal computer. (author)

  11. Two-phase jet impingement cooling for high heat flux wide band-gap devices using multi-scale porous surfaces

    International Nuclear Information System (INIS)

    Joshi, Shailesh N.; Dede, Ercan M.

    2017-01-01

    Highlights: • Jet impingement with phase change on multi-scale porous surfaces is investigated. • Porous coated flat, pin-fin, open tunnel, and closed tunnel structures are studied. • Boiling curve, heat transfer coefficient, and pressure drop metrics are reported. • Flow visualization shows vapor removal from the surface is a key aspect of design. • The porous coated pin-fin surface exhibits superior two-phase cooling performance. - Abstract: In the future, wide band-gap (WBG) devices such as silicon carbide and gallium nitride will be widely used in automotive power electronics due to performance advantages over silicon-based devices. The high heat fluxes dissipated by WBG devices pose extreme cooling challenges that demand the use of advanced thermal management technologies such as two-phase cooling. In this light, we describe the performance of a submerged two-phase jet impingement cooler in combination with porous coated heat spreaders and multi-jet orifices. The cooling performance of four different porous coated structures was evaluated using R-245fa as the coolant at sub-cooling of 5 K. The results show that the boiling performance of a pin-fin heat spreader is the highest followed by that for an open tunnel (OPT), closed tunnel (CLT), and flat heat spreader. Furthermore, the flat heat spreader demonstrated the lowest critical heat flux (CHF), while the pin-fin surface sustained a heat flux of 218 W/cm 2 without reaching CHF. The CHF values of the OPT and CLT surfaces were 202 W/cm 2 and 194 W/cm 2 , respectively. The pin-fin heat spreader has the highest two-phase heat transfer coefficient of 97,800 W/m 2 K, while the CLT surface has the lowest heat transfer coefficient of 69,300 W/m 2 K, both at a heat flux of 165 W/cm 2 . The variation of the pressure drop of all surfaces is similar for the entire range of heat fluxes tested. The flat heat spreader exhibited the least pressure drop, 1.73 kPa, while the CLT surface had the highest, 2.17 kPa at a

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

    Directory of Open Access Journals (Sweden)

    Razam Ab Latip

    2013-05-01

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

  13. Evidence of refilled chamber gas pressure enhancing cooling rate during melt spinning of a Zr50Cu40Al10 alloy

    Directory of Open Access Journals (Sweden)

    Hong-wang Yang

    2015-07-01

    Full Text Available The influence of the refilled gas pressure on the glass forming behaviour of one of the best ternary glass forming alloys Zr50Cu40Al10 was studied for the melt spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD and differential scanning calorimetry (DSC. The refilled chamber atmospheric pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.0001 atm, fully crystalline fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1 atm or higher. The extended contact length between thecribbons and the copper wheel contributes to the high cooling rate of melt spinning. Higher chamber gas pressure leads to more turbulence of liquid metal beneath the nozzle; therefore, lower pressure is preferable at practical melt spinning processes once glass forming conditions are fulfilled.

  14. Effect of Cooling Rate on Precipitation Behavior and Micromechanical Properties of Ferrite in V-N Alloyed Steel During a Simulated Thermomechanical Process

    Science.gov (United States)

    Zhang, Jing; Wang, Fu-Ming; Yang, Zhan-Bing; Li, Chang-Rong

    2017-12-01

    The effect of the cooling rate after finish deformation at 1223 K (950 °C) on the microstructural evolution, V(C,N) precipitation, and micromechanical properties of ferrite in high-N V-alloyed building steel was comparatively investigated using a Gleeble-1500 thermomechanical simulator. Metallographic analysis shows that polygonal ferrite (PF) and pearlite (P) were dominant microconstituents at cooling rates ranging from 0.5 K/s to 3 K/s (0.5 °C/s to 3 °C/s). As the cooling rate increased within this range, the average ferrite grain size decreased from 6.1 ± 0.30 to 4.4 ± 0.25 μm. Besides, the sheet spacing of interphase precipitated V(C,N) particles decreased from 64.0 to 78.7 to 21.9 to 24.5 nm, and the average size of randomly precipitated particles was refined from 8.2 ± 3.24 to 6.3 ± 2.18 nm. The number density of precipitates with a size below and above 10 nm decreased, and the total number density decreased from 2482 ± 430 to 1699 ± 142 μm-2. Moreover, high-resolution transmission electron microscopy (HRTEM) observation revealed that there exists a coherent interface between the nanoscaled V(C,N) particle and the ferrite matrix. This interface lowered the nucleation energy barrier and promoted the V(C,N) particle precipitation in the ferrite matrix. Nanoindentation measurements indicated that the ferrite phase became softer, and the corresponding value of nanohardness and Young's modulus decreased as the cooling rate increased, which was caused predominantly by the decrease in precipitation hardening due to the lower number density of V(C,N) precipitates.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  16. Infrared surface temperature measurements for long pulse operation, and real time feedback control in Tore-Supra, an actively cooled Tokamak

    International Nuclear Information System (INIS)

    Guilhem, D.; Adjeroud, B.; Balorin, C.; Buravand, Y.; Bertrand, B.; Bondil, J.L.; Desgranges, C.; Gauthier, E.; Lipa, M.; Messina, P.; Missirlian, M.; Mitteau, R.; Moulin, D.; Pocheau, C.; Portafaix, C.; Reichle, R.; Roche, H.; Saille, A.; Vallet, S.

    2004-01-01

    Tore-Supra has a steady-state magnetic field using super-conducting magnets and water-cooled plasma facing components for high performances long pulse plasma discharges. When not actively cooled, plasma-facing components can only accumulate a limited amount of energy since the temperature increase continuously (T proportional to √(t)) during the discharge until radiation cooling is equal to the incoming heat flux (T > 1800 K). Such an environment is found in most today Tokamaks. In the present paper we report the recent results of Tore-Supra, especially the design of the new generation of infrared endoscopes to measure the surface temperature of the plasma facing components. The Tore-Supra infrared thermography system is composed of 7 infrared endoscopes, this system is described in details in the paper, the new JET infrared thermography system is presented and some insights of the ITER set of visible/infrared endoscope is given. (authors)

  17. Infrared surface temperature measurements for long pulse operation, and real time feedback control in Tore-Supra, an actively cooled Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Guilhem, D.; Adjeroud, B.; Balorin, C.; Buravand, Y.; Bertrand, B.; Bondil, J.L.; Desgranges, C.; Gauthier, E.; Lipa, M.; Messina, P.; Missirlian, M.; Mitteau, R.; Moulin, D.; Pocheau, C.; Portafaix, C.; Reichle, R.; Roche, H.; Saille, A.; Vallet, S

    2004-07-01

    Tore-Supra has a steady-state magnetic field using super-conducting magnets and water-cooled plasma facing components for high performances long pulse plasma discharges. When not actively cooled, plasma-facing components can only accumulate a limited amount of energy since the temperature increase continuously (T proportional to {radical}(t)) during the discharge until radiation cooling is equal to the incoming heat flux (T > 1800 K). Such an environment is found in most today Tokamaks. In the present paper we report the recent results of Tore-Supra, especially the design of the new generation of infrared endoscopes to measure the surface temperature of the plasma facing components. The Tore-Supra infrared thermography system is composed of 7 infrared endoscopes, this system is described in details in the paper, the new JET infrared thermography system is presented and some insights of the ITER set of visible/infrared endoscope is given. (authors)

  18. On synthesis and optimization of cooling water systems with multiple cooling towers

    CSIR Research Space (South Africa)

    Gololo, KV

    2011-01-01

    Full Text Available Cooling water systems are generally designed with a set of heat exchangers arranged in parallel. This arrangement results in higher cooling water flow rate and low cooling water return temperature, thus reducing cooling tower efficiency. Previous...

  19. Heat and turbulent kinetic energy budgets for surface layer cooling induced by the passage of Hurricane Frances (2004)

    Science.gov (United States)

    Huang, Peisheng; Sanford, Thomas B.; Imberger, JöRg

    2009-12-01

    Heat and turbulent kinetic energy budgets of the ocean surface layer during the passage of Hurricane Frances were examined using a three-dimensional hydrodynamic model. In situ data obtained with the Electromagnetic-Autonomous Profiling Explorer (EM-APEX) floats were used to set up the initial conditions of the model simulation and to compare to the simulation results. The spatial heat budgets reveal that during the hurricane passage, not only the entrainment in the bottom of surface mixed layer but also the horizontal water advection were important factors determining the spatial pattern of sea surface temperature. At the free surface, the hurricane-brought precipitation contributed a negligible amount to the air-sea heat exchange, but the precipitation produced a negative buoyancy flux in the surface layer that overwhelmed the instability induced by the heat loss to the atmosphere. Integrated over the domain within 400 km of the hurricane eye on day 245.71 of 2004, the rate of heat anomaly in the surface water was estimated to be about 0.45 PW (1 PW = 1015 W), with about 20% (0.09 PW in total) of this was due to the heat exchange at the air-sea interface, and almost all the remainder (0.36 PW) was downward transported by oceanic vertical mixing. Shear production was the major source of turbulent kinetic energy amounting 88.5% of the source of turbulent kinetic energy, while the rest (11.5%) was attributed to the wind stirring at sea surface. The increase of ocean potential energy due to vertical mixing represented 7.3% of the energy deposited by wind stress.

  20. Cooling tower calculations

    International Nuclear Information System (INIS)

    Simonkova, J.

    1988-01-01

    The problems are summed up of the dynamic calculation of cooling towers with forced and natural air draft. The quantities and relations are given characterizing the simultaneous exchange of momentum, heat and mass in evaporative water cooling by atmospheric air in the packings of cooling towers. The method of solution is clarified in the calculation of evaporation criteria and thermal characteristics of countercurrent and cross current cooling systems. The procedure is demonstrated of the calculation of cooling towers, and correction curves and the effect assessed of the operating mode at constant air number or constant outlet air volume flow on their course in ventilator cooling towers. In cooling towers with the natural air draft the flow unevenness is assessed of water and air relative to its effect on the resulting cooling efficiency of the towers. The calculation is demonstrated of thermal and resistance response curves and cooling curves of hydraulically unevenly loaded towers owing to the water flow rate parameter graded radially by 20% along the cross-section of the packing. Flow rate unevenness of air due to wind impact on the outlet air flow from the tower significantly affects the temperatures of cooled water in natural air draft cooling towers of a design with lower demands on aerodynamics, as early as at wind velocity of 2 m.s -1 as was demonstrated on a concrete example. (author). 11 figs., 10 refs

  1. Influence of deposition rate on PL spectrum and surface morphology ...

    Indian Academy of Sciences (India)

    A conventional oven in open air with average humidity of 60% was used for thermal oxidation of Zn films and the samples oxidation took place at 400. ◦. C temperatures. In this work, six samples with dif- ferent deposition rates were coated. To change the coating rates of zinc (0·6–4·5 nm/s), the discharge current was var-.

  2. Evolution of the thickness of the aluminum oxide film due to the pH of the cooling water and surface temperature of the fuel elements clad of a nuclear reactor

    International Nuclear Information System (INIS)

    Babiche, Ivan

    2013-01-01

    This paper describes the mechanism of growth of a film of aluminum oxide on an alloy of the same material, which serves as a protective surface being the constituent material of the RP-10 nuclear reactor fuel elements clads. The most influential parameters on the growth of this film are: the pH of the cooling water and the clad surface temperature of the fuel element. For this study, a mathematical model relating the evolution of the aluminum oxide layer thickness over the time, according to the same oxide film using a power law is used. It is concluded that the time of irradiation, the heat flux at the surface of the aluminum material, the speed of the coolant, the thermal conductivity of the oxide, the initial thickness of the oxide layer and the solubility of the protective oxide are parameters affecting in the rate and film formation. (author).

  3. Effect of Cooling Rate on the Longitudinal Modulus of Cu3Sn Phase of Ag-Sn-Cu Amalgam Alloy (Part II

    Directory of Open Access Journals (Sweden)

    R. H. Rusli

    2015-10-01

    Full Text Available Effects of cooling rate (at the time of solidification on the elastic constants of Cu3Sn phase of Ag-Sn-Cu dental amalgam alloy were studied. In this study, three types of alloys were made, with the composition Cu-38-37 wt% Sn by means of casting, where each alloy was subjected to different cooling rate, such as cooling on the air (AC, air blown (AB, and quenched in the water (WQ. X-ray diffraction, metallography, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy studies of three alloys indicated the existence of Cu3Sn phase. Determination of the modulus of elasticity of Cu3Sn (ε phase was carried out by the measurement of longitudinal and transversal waves velocity using ultrasonic technique. The result shows that Cu3Sn (ε phase on AC gives higher modulus of elasticity values than those of Cu3Sn (ε on AB and WQ. The high modulus of elasticity value will produce a strong Ag-Sn-Cu dental amalagam alloy.

  4. Influence of cooling rate on the structure and mechanical properties of G17CrMoV5 – 10 cast steel

    Directory of Open Access Journals (Sweden)

    G. Golański

    2009-07-01

    Full Text Available The paper presents results of research on the influence of cooling rate on the structure and properties of G17CrMoV5 – 10 (L17HMF cast steel. The material for research was a section taken out from an outer cylinder of a steam turbine body after about 250 000 hours of operation at the temperature of 535°C and pressure 9 MPa. The investigated cast steel was subjected to heat treatment which consisted in cooling at the rates corresponding to the processes, such as: bainitic hardening, normalizing and full annealing. Tempering after the process of cooling from austenitizing temperature was carried out at the temperatures of: 700, 720 and 740°C. Performed research has proved that structures obtained after bainitic hardening and normalizing are characterized by a large strength margin which allows to apply high temperatures of tempering. It has been shown that the cast steel of bainitic structure, with similar mechanical properties as the cast steel of bainitic – ferritic structure, is characterized by almost twice as high impact energy. Full annealing and tempering of the examined cast steel ensures only the required impact strength, with mechanical properties comparable to those after service.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Eolian erosion of the Martian surface. I - Erosion rate similitude

    Science.gov (United States)

    Iversen, J. D.; White, B. R.; Greeley, R.; Pollack, J. B.

    1975-01-01

    A similitude parameter is derived which is based on theoretical considerations of erosion due to sand in saltation. This parameter has been used to correlate wind tunnel experiments of particle flow over model craters. The characteristics of the flow field in the vicinity and downstream of a crater are discussed and it is shown that erosion is initiated in areas lying under a pair of trailing vortices. The erosion rate parameter is used to calculate erosion rates on Mars, reported in Part 2, to be published later.

  8. Monitoring peak power and cooling energy savings of shade trees and white surfaces in the Sacramento Municipal Utility District (SMUD) service area: Project design and preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, H.; Bretz, S.; Hanford, J.; Rosenfeld, A.; Sailor, D.; Taha, H. [Lawrence Berkeley Lab., CA (United States); Bos, W. [Sacramento Municipal Utility District, CA (United States)

    1992-12-01

    Urban areas in warm climates create summer heat islands of daily average intensity of 3--5{degrees}C, adding to discomfort and increasing air-conditioning loads. Two important factors contributing to urban heat islands are reductions in albedo (lower overall city reflectance) and loss of vegetation (less evapotranspiration). Reducing summer heat islands by planting vegetation (shade trees) and increasing surface albedos, saves cooling energy, allows down-sizing of air conditioners, lowers air-conditioning peak demand, and reduces the emission of CO{sub 2} and other pollutants from electric power plants. The focus of this multi-year project, jointly sponsored by SMUD and the California Institute for Energy Efficiency (CIEE), was to measure the direct cooling effects of trees and white surfaces (mainly roofs) in a few buildings in Sacramento. The first-year project was to design the experiment and obtain base case data. We also obtained limited post retrofit data for some sites. This report provides an overview of the project activities during the first year at six sites. The measurement period for some of the sites was limited to September and October, which are transitional cooling months in Sacramento and hence the interpretation of results only apply to this period. In one house, recoating the dark roof with a high-albedo coating rendered air conditioning unnecessary for the month of September (possible savings of up to 10 kWh per day and 2 kW of non-coincidental peak power). Savings of 50% relative to an identical base case bungalow were achieved when a school bungalow`s roof and southeast wall were coated with a high-albedo coating during the same period. Our measured data for the vegetation sites do not indicate conclusive results because shade trees were small and the cooling period was almost over. We need to collect more data over a longer cooling season in order to demonstrate savings conclusively.

  9. Cryopreservation of boar semen. II: Effect of cooling rate and duration of freezing point plateau on boar semen frozen in mini- and maxi-straws and plastic bags.

    Science.gov (United States)

    Bwanga, C O; Einarsson, S; Rodriguez-Martinez, H

    1991-01-01

    The post-thaw motility and the acrosome integrity of semen from 4 boars frozen with a programmable freezing machine, in mini (0.25 ml) and maxi (5 ml) plastic straws and in 10 x 5 cm Teflon FEP-plastic bags (0.12 mm thick, 5 ml), were compared. The freezing of the semen was monitored by way of thermo-couples placed in the straws and the bags. Three freezing programmes were used, namely A: from +5 degrees C, at a rate of 3 degrees C/min, to -6 degrees C, held for 1 min at -6 degrees C, and followed by a cooling rate of 20 degrees C/min to -100 degrees C; B: a similar curve except that there was no holding time at -6 degrees C and that the cooling rate was 30 degrees C/min, and C: from +5 degrees C to -100 degrees C, with a cooling rate of 35 degrees C/min, followed by storage in liquid N2. Despite the freezing curve assayed, both the mini-straws and the bags depicted much shorter freezing point plateaus as compared to the maxi-straws. Post-thaw sperm motility as well as the amount of normal apical ridges were equally significantly higher when semen was frozen in mini-straws or in bags than in maxi-straws. Significant differences in these post-thawing parameters were obtained between the freezing curves used. The stepwise freezing procedure A appeared as the best alternative for boar semen, considering this in vitro evaluation.

  10. Properties of water surface discharge at different pulse repetition rates

    Czech Academy of Sciences Publication Activity Database

    Ruma, R.; Hosseini, S.H.R.; Yoshihara, K.; Akiyama, M.; Sakugawa, T.; Lukeš, Petr; Akiyama, H.

    2014-01-01

    Roč. 116, č. 12 (2014), s. 123304-123304 ISSN 0021-8979 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : plasma in air * water surface discharge * pulse frequency * hydrogen peroxide * organic dye Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.183, year: 2014 http://dx.doi.org/ 10.1063/1.4896266

  11. Empirical recurrence rates for ground motion signals on planetary surfaces

    Science.gov (United States)

    Lorenz, Ralph D.; Panning, Mark

    2018-03-01

    We determine the recurrence rates of ground motion events as a function of sensed velocity amplitude at several terrestrial locations, and make a first interplanetary comparison with measurements on the Moon, Mars, Venus and Titan. This empirical approach gives an intuitive order-of-magnitude guide to the observed ground motion (including both tectonic and ocean- and atmosphere-forced signals) of these locations as a guide to instrument expectations on future missions, without invoking interior models and specific sources: for example a Venera-14 observation of possible ground motion indicates a microseismic environment mid-way between noisy and quiet terrestrial locations. Quiet terrestrial regions see a peak velocity amplitude in mm/s roughly equal to 0.3*N(-0.7), where N is the number of "events" (half-hour intervals in which a given peak ground motion is exceeded) observed per year. The Apollo data show endogenous seismic signals for a given recurrence rate that are typically about 10,000 times smaller in amplitude than a quiet site on Earth, although local thermally-induced moonquakes are much more common. Viking data masked for low-wind periods appear comparable with a quiet terrestrial site, whereas a Venera observation of microseisms suggests ground motion more similar to a more active terrestrial location. Recurrence rate plots from in-situ measurements provide a context for seismic instrumentation on future planetary missions, e.g. to guide formulation of data compression schemes. While even small geophones can discriminate terrestrial activity rates, observations with guidance accelerometers are typically too insensitive to provide meaningful constraints (i.e. a non-zero number of "events") on actual ground motion observations unless operated for very long periods.

  12. Influence of Cooling Rate on Growth of Bacillus cereus from Spore Inocula in Cooked Rice, Beans, Pasta, and Combination Products Containing Meat or Poultry.

    Science.gov (United States)

    Juneja, Vijay K; Mohr, Tim B; Silverman, Meryl; Snyder, O Peter

    2018-02-23

    The objective of this study was to assess the ability of Bacillus cereus spores to germinate and grow in order to determine a safe cooling rate for cooked rice, beans, and pasta, rice-chicken (4:1), rice-chicken-vegetables (3:1:1), rice-beef (4:1), and rice-beef-vegetables (3:1:1). Samples were inoculated with a cocktail of four strains of heat-shocked (80°C for 10 min) B. cereus spores (NCTC 11143, 935A/74, Brad 1, and Mac 1) to obtain a final spore concentration of approximately 2 log CFU/g. Thereafter, samples were exponentially cooled through the temperature range of 54.5 to 7.2°C in 6, 9, 12, 15, 18, and 21 h. At the end of the cooling period, samples were removed and plated on mannitol egg yolk polymyxin agar. The plates were incubated at 30°C for 24 h. The net B. cereus growth from spores in beans was beans, pasta, rice-chicken, rice-chicken-vegetables, rice-beef, and rice-beef-vegetables to guard against the hazards associated with B. cereus.

  13. Cooling of wood briquettes

    Directory of Open Access Journals (Sweden)

    Adžić Miroljub M.

    2013-01-01

    Full Text Available This paper is concerned with the experimental research of surface temperature of wood briquettes during cooling phase along the cooling line. The cooling phase is an important part of the briquette production technology. It should be performed with care, otherwise the quality of briquettes could deteriorate and possible changes of combustion characteristics of briquettes could happen. The briquette surface temperature was measured with an IR camera and a surface temperature probe at 42 sections. It was found that the temperature of briquette surface dropped from 68 to 34°C after 7 minutes spent at the cooling line. The temperature at the center of briquette, during the 6 hour storage, decreased to 38°C.

  14. Effect of surface roughness on the heating rates of large-angled hypersonic blunt cones

    Science.gov (United States)

    Irimpan, Kiran Joy; Menezes, Viren

    2018-03-01

    Surface-roughness caused by the residue of an ablative Thermal Protection System (TPS) can alter the turbulence level and surface heating rates on a hypersonic re-entry capsule. Large-scale surface-roughness that could represent an ablated TPS, was introduced over the forebody of a 120° apex angle blunt cone, in order to test for its influence on surface heating rates in a hypersonic freestream of Mach 8.8. The surface heat transfer rates measured on smooth and roughened models under the same freestream conditions were compared. The hypersonic flow-fields of the smooth and rough-surfaced models were visualized to analyse the flow physics. Qualitative numerical simulations and pressure measurements were carried out to have an insight into the high-speed flow physics. Experimental observations under moderate Reynolds numbers indicated a delayed transition and an overall reduction of 17-46% in surface heating rates on the roughened model.

  15. Experimental characterization of fatigue strength in butt welded joint considering the geometry and the effect of cooling rate of the weld

    Science.gov (United States)

    Arzola, Nelson; Hernández, Edgar

    2017-05-01

    In this work the experimental characterization of fatigue strength in butt welded joints considering the geometry and the post-weld cooling cycle was performed. ASTM A-36 structural steel was used as the base metal for the shielded metal arc welding process, with welding electrode E6013. Two experimental factors were established: weld bead geometry and the post-weld cooling rate. Two levels for each factor, the welding reinforcement (1 and 3 mm), and the rate of cooling, slow (quiet air) and fast (immersion in water) are evaluated respectively. For the uniaxial fatigue tests, 8 samples were selected for each treatment for a total of 32 specimens. The mechanical and fractomechanical properties of fusion zone, heat affected zone and base metal in relation to the analysis of failure mechanisms were analysed. The fatigue crack growth rates were estimated based on the counting of microstrations. Furthermore, experimental tests, such as uniaxial tension, microindentation hardness, Charpy impact and metallographic analysis, were made to know the influence of the experimental factors in the fatigue strength. On this research, about the 78.13% of the samples obtained a resistance higher than the recommended one by class FAT 100. The results showed that the geometry of the joint is the factor of greatest influence on fatigue strength for butt welded joints; the greater the weld reinforcement the lower the fatigue strength of the joint. Although it is also important to consider other geometric factors of less impact as it is the weld toe radius and the welding chord width.

  16. NASA Microclimate Cooling Challenges

    Science.gov (United States)

    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.

  17. Surface Roughness effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

    Science.gov (United States)

    Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt l...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Effect of Cooling Rate on the Longitudinal Modulus of Cu3Sn Phase of Ag-Sn-Cu Amalgam Alloy (Part I

    Directory of Open Access Journals (Sweden)

    R. H. Rusli

    2015-10-01

    Full Text Available Cu3Sn is indeed the ε phase in the Copper-Tin system, which is one of the main phase of High Copper Amalgam Alloy (Ag-Sn-Cu Alloy and at present very little emphasis has been placed on the microstructure and the mechanical properties of Cu3Sn phase. In this study 3 castings of Cu-38.37 wt% Sn were produced. The casting specimens were subjected to different cooling rate conditions: as cast, air blown, and water quenched. The possible phases were identified by x-ray diffraction and the microstructure were examined on a metallurgy optical microscope. An ultrasonic equipment were utilized for longitudinal wave velocity measurements. Using this velocity the longitudinal modulus can be calculated. Phase identification on as cast, air blown and water quenched specimens indicated that the specimens consist of ε (Cu3Sn phase. The smaller and finer microstructure of Cu3Sn phase was produced from water quenched (faster cooling rate specimen. However its longitudinal modulus is significantly lower than the longitudinal modulus of as cast and air blown specimens. Therefore it is still need further investigation in order to obtain the transversal wave velocity and the Young's modulus.

  1. The COMET-L3 experiment on long-term melt. Concrete interaction and cooling by surface flooding

    International Nuclear Information System (INIS)

    Alsmeyer, H.; Cron, T.; Fluhrer, B.; Messemer, G.; Miassoedov, A.; Schmidt-Stiefel, S.; Wenz, T.

    2007-02-01

    The COMET-L3 experiment considers the long-term situation of corium/concrete interaction in an anticipated core melt accident of a light-water-reactor, after the metal melt is layered beneath the oxide melt. The experimental focus is on cavity formation in the basemat and the risk of long term basemat penetration. The experiment investigates the two-dimensional concrete erosion in a cylindrical crucible fabricated from siliceous concrete in the first phase of the test, and the influence of surface flooding in the second phase. Decay heating in the two-component metal and oxide melt is simulated by sustained induction heating of the metal phase that is overlaid by the oxide melt. The inner diameter of the concrete crucible was 60 cm, the initial mass of the melt was 425 kg steel and 211 kg oxide at 1665 C, resulting in a melt height of 450 mm. The net power to the metal melt was about 220 kW from 0 s to 1880 s, when the maximum erosion limit of the crucible was reached and heating was terminated. In the initial phase of the test (less than 100 s), the overheated, highly agitated metal melt causes intense interaction with the concrete, which leads to fast decrease of the initial melt overheat and reduction of the initially high concrete erosion rate. Thereafter, under quasistationary conditions until about 800 s, the erosion by the metal melt slows down to some 0.07 mm/s into the axial direction. Lateral erosion is a factor 3 smaller. Video observation of the melt surface shows an agitated melt with ongoing gas release from the decomposing concrete. Several periods of more intense gas release, gas driven splashing, and release of crusts from the concrete interface indicate the existence and iterative break-up of crusts that probably form at the steel/concrete interface. Surface flooding of the melt is initiated at 800 s by a shower from the crucible head with 0.375 litre water/s. Flooding does not lead to strong melt/water interactions, and no entrapment reactions or

  2. Conjugate Heat Transfer Study at Interior Surface of NGV Leading Edge with Combined Shower Head and Impingement Cooling

    OpenAIRE

    Arun Kumar Pujari; B. V. S. S. S. Prasad; N. Sitaram

    2014-01-01

    A computational study on conjugate heat transfer is carried out to present the behavior of nondimensional temperature and heat transfer coefficient of a Nozzle Guide Vane (NGV) leading edge. Reynolds number of both mainstream flow and coolant impinging jets are varied. The NGV has five rows of film cooling holes arranged in shower head manner and four rows of impingement holes arranged in staggered manner. The results are presented by considering materials of different thermal conductivity. T...

  3. NUMERICAL MODELING OF STRESSES NEAR THE SURFACE IN THE INGOT OF CIRCULAR SECTION, CRYSTALLIZABLE AT CIRCULAR TORCH SECONDARY COOLING

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2004-01-01

    Full Text Available The results of computer calculations of the stresses, generated in outside layer of ingot of steel 20 of circular section with diameter 300 mm, in application to one of the industrial technological schemas of RUP “BMZ”, are presented. The segments of compressive and tensile stresses formation along the length of ingot are determined and the principal possibility of production of continuously cast slug of circular section at circular-torch spray cooling is shown.

  4. Effect of surface roughness on erosion rates of pure copper coupons in pulsed vacuum arc system

    International Nuclear Information System (INIS)

    Rao, Lakshminarayana; Munz, Richard J

    2007-01-01

    Vacuum arc erosion measurements were performed on copper cathodes having different surface roughness and surface patterns in 10 -5 Torr vacuum (1.3324 mPa), in an external magnetic field of 0.04 T. Different surface patterns and surface roughness were created by grit blasting with alumina grits (G-cathodes) and grinding with silicon carbide emery paper (E-cathodes). The erosion rates of these cathodes were obtained by measuring the weight loss of the electrode after igniting as many as 135 arc pulses, each of which was 500 μs long at an arc current of 125 A. The erosion rates measured indicate that erosion rates decrease with decreasing roughness levels. Results obtained indicate that both surface roughness and surface patterns affect the erosion rate. Having patterns perpendicular to the direction of cathode spot movement gives lower erosion rates than having patterns parallel to arc movement. Isotropic surfaces give lower erosion rates than patterned surfaces at the same roughness

  5. Comparison of tool life and surface roughness with MQL, flood cooling, and dry cutting conditions with P20 and D2 steel

    Science.gov (United States)

    Senevirathne, S. W. M. A. I.; Punchihewa, H. K. G.

    2017-09-01

    Minimum quantity lubrication (MQL) is a cutting fluid (CF) application method that has given promising results in improving machining performances. It has shown that, the performance of cutting systems, depends on the work and tool materials used. AISI P20, and D2 are popular in tool making industry. However, the applicability of MQL in machining these two steels has not been studied previously. This experimental study is focused on evaluating performances of MQL compared to dry cutting, and conventional flood cooling method. Trials were carried out with P20, and D2 steels, using coated carbides as tool material, emulsion cutting oil as the CF. Tool nose wear, and arithmetic average surface roughness (Ra) were taken as response variables. Results were statistically analysed for differences in response variables. Although many past literature has suggested that MQL causes improvements in tool wear, and surface finish, this study has found contradicting results. MQL has caused nearly 200% increase in tool nose wear, and nearly 11-13% increase in surface roughness compared flood cooling method with both P20 and D2. Therefore, this study concludes that MQL affects adversely in machining P20, and D2 steels.

  6. Impact of the surface roughness of AISI 316L stainless steel on biofilm adhesion in a seawater-cooled tubular heat exchanger-condenser.

    Science.gov (United States)

    García, Sergio; Trueba, Alfredo; Vega, Luis M; Madariaga, Ernesto

    2016-11-01

    The present study evaluated biofilm growth in AISI 316L stainless steel tubes for seawater-cooled exchanger-condensers that had four different arithmetic mean surface roughness values ranging from 0.14 μm to 1.2 μm. The results of fluid frictional resistance and heat transfer resistance regarding biofilm formation in the roughest surface showed increases of 28.2% and 19.1% respectively, compared with the smoothest surface. The biofilm thickness taken at the end of the experiment showed variations of up to 74% between the smoothest and roughest surfaces. The thermal efficiency of the heat transfer process in the tube with the roughest surface was 17.4% greater than that in the tube with the smoothest surface. The results suggest that the finish of the inner surfaces of the tubes in heat exchanger-condensers is critical for improving energy efficiency and avoiding biofilm adhesion. This may be utilised to reduce biofilm adhesion and growth in the design of heat exchanger-condensers.

  7. The Role of the Cooling Prescription for Disk Fragmentation: Numerical Convergence and Critical Cooling Parameter in Self-gravitating Disks

    Science.gov (United States)

    Baehr, Hans; Klahr, Hubert

    2015-12-01

    Protoplanetary disks fragment due to gravitational instability when there is enough mass for self-gravitation, described by the Toomre parameter, and when heat can be lost at a rate comparable to the local dynamical timescale, described by {t}{{c}}=β {{{Ω }}}-1. Simulations of self-gravitating disks show that the cooling parameter has a rough critical value at {β }{{crit}}=3. When below {β }{{crit}}, gas overdensities will contract under their own gravity and fragment into bound objects while otherwise maintaining a steady state of gravitoturbulence. However, previous studies of the critical cooling parameter have found dependences on simulation resolution, indicating that the simulation of self-gravitating protoplanetary disks is not so straightforward. In particular, the simplicity of the cooling timescale tc prevents fragments from being disrupted by pressure support as temperatures rise. We alter the cooling law so that the cooling timescale is dependent on local surface density fluctuations, which is a means of incorporating optical depth effects into the local cooling of an object. For lower resolution simulations, this results in a lower critical cooling parameter and a disk that is more stable to gravitational stresses, suggesting that the formation of large gas giants planets in large, cool disks is generally suppressed by more realistic cooling. At our highest resolution, however, the model becomes unstable to fragmentation for cooling timescales up to β =10.

  8. Turbine airfoil film cooling

    Science.gov (United States)

    Hylton, L. D.; Nirmalan, V.; Sultanian, B. K.; Kaufman, R. M.

    1987-10-01

    The experimental data obtained in this program gives insight into the physical phenomena that occur on a film cooled airfoil, and should provide a relevant data base for verification of new design tools. Results indicate that the downstream film cooling process is a complex function of the thermal dilution and turbulence augmentation parameters with trends actually reversing as blowing strength and coolant-to-gas temperature ratio varied. The pressure surface of the airfoil is shown to exhibit a considerably higher degree of sensitivity to changes in the film cooling parameters and, consequently, should prove to be more of a challenge than the suction surface in accurately predicting heat transfer levels with downsteam film cooling.

  9. Measurements of dry-deposition rates on various earth surfaces by 212Pb

    International Nuclear Information System (INIS)

    Osaki, S.; Sugihara, S.; Maeda, Y.

    2004-01-01

    Dry deposition rates of 212 Pb on a coniferous forest (Japanese cedar) and a broad-leaf forest (Pasania edulis) have been measured. Those on various kinds of grass fields, various states on artificial surface such as water, paper, and standing paper have been also measured. The dry deposition rates depend on the characteristics of depositing particles and the conditions of deposited surfaces. Dry deposition rates on the forest of Japanese cedar are highest because of the complex and adhesive surface of the leaves. Those on various grass fields are roughly depend on the logarithm of the height of their grasses. The total deposition rates of 7 Be do not depend on the densities or heights of the grasses. 7 Be may be not kept on their leaves or surface soil for a long time. The dry deposition rates of on artificial surface, e.g. paper and water surfaces make clear the mechanism on dry deposition, and suggest that more chances of collision and more adhesive of the surface are important for the dry deposition. About 90% of all deposition on the artificial paper grass was attached on the standing paper. On water surface, 60% of the rate of paper grass was attached, but only about 20% were attached on a dry paper plate. The aerosol particles are deposited by collision with the surface, therefore the deposition velocity depends on the chance of collision and the characteristics of the surface. Therefore the dry deposition rates on forests are larger and those of coniferous forest are largest. (author)

  10. A theoretically estimated optimal cooling rate for the cryopreservation of sperm cells from a live-bearing fish, the green swordtail Xiphophorus helleri.

    Science.gov (United States)

    Thirumala, Sreedhar; Huang, Changjiang; Dong, Qiaoxiang; Tiersch, Terrence R; Devireddy, Ram V

    2005-06-01

    Sperm cryopreservation of live-bearing fishes, such as those of the genus Xiphophorus is only beginning to be studied, although these fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. To explore optimization of techniques for sperm cryopreservation of these fishes, this study measured the volumetric shrinkage response during freezing of sperm cells of Xiphophorus helleri by use of a shape-independent differential scanning calorimeter (DSC) technique. Volumetric shrinkage during freezing of X. helleri sperm cell suspensions was obtained in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol; and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder of 33.3 microm in length and 0.59 microm in diameter with an osmotically inactive cell volume (V(b)) of 0.6V(o), where V(o) is the isotonic or initial cell volume. By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best-fit membrane permeability parameters (reference membrane permeability to water, L(pg) or L(pg)[cpa] and the activation energy, E(Lp) or E(Lp)[cpa]) of the Xiphophorus helleri sperm cell membrane were determined. The best-fit membrane permeability parameters at 20 degrees C/min in the absence of CPAs were: L(pg)=0.776 x 10(-15)m3/Ns (0.0046 microm/min atm), and E(Lp)=50.1 kJ/mol (11.97 kcal/mol) (R2=0.997). The corresponding parameters in the presence of 14% glycerol were L(pg)[cpa]=1.063 x 10(-15)m3/Ns (0.0063 microm/min atm), and E(Lp)[cpa]=83.81 kJ/mol (20.04 kcal/mol) (R2=0.997). The parameters in the presence of 10% DMSO were L(pg)[cpa]=1.4 x 10(-15)m3/Ns (0.0083 microm/min atm), and E(Lp)[cpa]=90.96 kJ/mol (21.75 kcal/mol) (R2=0.996). Parameters obtained in this study suggested that the

  11. CONSTRAINTS ON THE SURFACE MAGNETIC FIELDS AND AGE OF A COOL HYPERGIANT: XMM-NEWTON X-RAY OBSERVATIONS OF VY CMa

    International Nuclear Information System (INIS)

    Montez, Rodolfo Jr.; Kastner, Joel H.; Humphreys, Roberta M.; Davidson, Kris; Turok, Rebecca L.

    2015-01-01

    The complex circumstellar ejecta of highly evolved, cool hypergiants are indicative of multiple, asymmetric mass-loss events. To explore whether such episodic, non-isotropic mass loss may be driven by surface magnetic activity, we have observed the archetypical cool hypergiant VY CMa with the XMM-Newton X-ray satellite observatory. The hypergiant itself is not detected in these observations. From the upper limit on the X-ray flux from VY CMa at the time of our observations (F X, UL ≈ 8 × 10 –14 erg cm –2 s –1 , corresponding to log L X /L bol ≤ –8), we estimate an average surface magnetic field strength fB ≤ 2 × 10 –3 G (where f is the filling factor of magnetically active surface regions). These X-ray results for VY CMa represent the most stringent constraints to date on the magnetic field strength near the surface of a hypergiant. VY CMa's mass loss is episodic, however, and the hypergiant may have been in a state of low surface magnetic activity during the XMM observations. The XMM observations also yield detections of more than 100 X-ray sources within ∼15' of VY CMa, roughly 50 of which have near-infrared counterparts. Analysis of X-ray hardness ratios and IR colors indicates that some of these field sources may be young, late-type stars associated with VY CMa, its adjacent molecular cloud complex, and the young cluster NGC 2362. Further study of the VY CMa field is warranted, given the potential to ascertain the evolutionary timescale of this enigmatic, massive star

  12. Spray cooling

    International Nuclear Information System (INIS)

    Rollin, Philippe.

    1975-01-01

    Spray cooling - using water spraying in air - is surveyed as a possible system for make-up (peak clipping in open circuit) or major cooling (in closed circuit) of the cooling water of the condensers in thermal power plants. Indications are given on the experiments made in France and the systems recently developed in USA, questions relating to performance, cost and environmental effects of spray devices are then dealt with [fr

  13. Method and apparatus for heat extraction by controlled spray cooling

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-30

    Two solutions to the problem of cooling a high temperature, high heat flux surface using controlled spray cooling are presented for use on a mandrel. In the first embodiment, spray cooling is used to provide a varying isothermal boundary layer on the side portions of a mandrel by providing that the spray can be moved axially along the mandrel. In the second embodiment, a spray of coolant is directed to the lower temperature surface of the mandrel. By taking advantage of super-Leidenfrost cooling, the temperature of the high temperature surface of the mandrel can be controlled by varying the mass flux rate of coolant droplets. The invention has particular applicability to the field of diamond synthesis using chemical vapor deposition techniques.

  14. Nonablative skin tightening with a variable depth heating 1310-nm wavelength laser in combination with surface cooling.

    Science.gov (United States)

    Alexiades-Armenakas, Macrene

    2007-11-01

    A near-infrared laser with the ability to target different depths within skin has been developed and evaluated for the application of facial and neck skin tightening in a pilot clinical study. The device consists of a combination of a 1310-nm wavelength and sapphire contact cooling. Cooling temperature and laser pulse duration were varied to target different dermal depths in various subgroups of the subject population. Quantitative changes in various categories characterizing the aging skin employing a comprehensive grading scale as well as subject satisfaction were calculated. A mean improvement of 7.9% (95% CI [confidence interval] 3.6-12.3) in laxity and 10.6% (95% CI 5.8-15.4) in rhytides was determined by quantitative grading at one month after the treatment regimen. These values were 11.0% (5.5-16.5) and 11.7% (5.8-17.7) at 3 months after the treatment regimen. The percent of patients reporting mild or better improvement in laxity of the face and neck was 78% and 61% at one month, and 63% and 61% at 3 months, respectively. The discomfort was minimal. Side effects were limited to short-term erythema and edema. In summary, a variable depth heating laser can achieve skin tightening and wrinkle reduction with high subject satisfaction.

  15. High energy resolution and high count rate gamma spectrometry measurement of primary coolant of generation 4 sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    Coulon, R.

    2010-01-01

    Sodium-cooled Fast Reactors are under development for the fourth generation of nuclear reactor. Breeders reactors could gives solutions for the need of energy and the preservation of uranium resources. An other purpose is the radioactive wastes production reduction by transmutation and the control of non-proliferation using a closed-cycle. These thesis shows safety and profit advantages that could be obtained by a new generation of gamma spectrometry system for SFR. Now, the high count rate abilities, allow us to study new methods of accurate power measurement and fast clad failure detection. Simulations have been done and an experimental test has been performed at the French Phenix SFR of the CEA Marcoule showing promising results for these new measurements. (author) [fr

  16. The effect of heating rate on the surface chemistry of NiTi.

    Science.gov (United States)

    Undisz, Andreas; Hanke, Robert; Freiberg, Katharina E; Hoffmann, Volker; Rettenmayr, Markus

    2014-11-01

    The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ~0.25 K s(-1) to 250 K s(-1). A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ~20 at.% at the lowest and ~1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ~3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Effects of short immersion time and cooling rates of copperizing process to the evolution of microstructures and copper behavior in the dead mild steel

    Science.gov (United States)

    Jatimurti, Wikan; Sutarsis, Cunika, Aprida Ulya

    2017-01-01

    In a dead mild steel with maximum carbon content of 0.15%, carbon does not contribute much to its strength. By adding copper as an alloying element, a balance between strength and ductility could be obtained through grain refining, solid solution, or Cu precipitation. This research aimed to analyse the changes in microstructures and copper behaviour on AISI 1006, including the phases formed, composition, and Cu dispersion. The addition of cooper was done by immersing steel into molten copper or so we called, copperizing using the principles of diffusion. Specimens were cut with 6 × 3 × 0.3 cm measurement then preheated to 900°C and melting the copper at 1100°C. Subsequently, the immersion of the specimens into molten copper varied to 5 and 7 minutes, and also varying the cooling rate to annealing, normalizing, and quenching. A series of test being conduct were optical microscope test, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), optical emission spectroscopy (OES), and X-ray diffraction (XRD). The results showed that the longer the immersion time and slower cooling rate, the more Cu diffused causing smaller grain size with the highest Cu diffused recorded was 0.277% in the copperized AISI 1006 steel with 7 minutes of immersion and was annealed. The grain size reduced to 23041.5404 µm2. The annealed specimens show ferrite phase, the normalized ones show polygonal ferrite phase, while the quenched ones show granular bainite phase. The phase formed is single phase Cu. In addition, the normalized and quenched specimens show that Cu dissolved in Fe crystal forming solid solution.

  18. Compressor bleed cooling fluid feed system

    Science.gov (United States)

    Donahoo, Eric E; Ross, Christopher W

    2014-11-25

    A compressor bleed cooling fluid feed system for a turbine engine for directing cooling fluids from a compressor to a turbine airfoil cooling system to supply cooling fluids to one or more airfoils of a rotor assembly is disclosed. The compressor bleed cooling fluid feed system may enable cooling fluids to be exhausted from a compressor exhaust plenum through a downstream compressor bleed collection chamber and into the turbine airfoil cooling system. As such, the suction created in the compressor exhaust plenum mitigates boundary layer growth along the inner surface while providing flow of cooling fluids to the turbine airfoils.

  19. Effects of Bacillus subtilis endospore surface reactivity on the rate of forsterite dissolution

    Science.gov (United States)

    Harrold, Z.; Gorman-Lewis, D.

    2013-12-01

    Primary mineral dissolution products, such as silica (Si), calcium (Ca) and magnesium (Mg), play an important role in numerous biologic and geochemical cycles including microbial metabolism, plant growth and secondary mineral precipitation. The flux of these and other dissolution products into the environment is largely controlled by the rate of primary silicate mineral dissolution. Bacteria, a ubiquitous component in water-rock systems, are known to facilitate mineral dissolution and may play a substantial role in determining the overall flux of dissolution products into the environment. Bacterial cell walls are complex and highly reactive organic surfaces that can affect mineral dissolution rates directly through microbe-mineral adsorption or indirectly by complexing dissolution products. The effect of bacterial surface adsorption on chemical weathering rates may even outweigh the influence of active processes in environments where a high proportion of cells are metabolically dormant or cell metabolism is slow. Complications associated with eliminating or accounting for ongoing metabolic processes in long-term dissolution studies have made it challenging to isolate the influence of cell wall interactions on mineral dissolution rates. We utilized Bacillus subtilis endospores, a robust and metabolically dormant cell type, to isolate and quantify the effects of bacterial surface reactivity on forsterite (Mg2SiO4) dissolution rates. We measured the influence of both direct and indirect microbe-mineral interactions on forsterite dissolution. Indirect pathways were isolated using dialysis tubing to prevent mineral-microbe contact while allowing free exchange of dissolved mineral products and endospore-ion adsorption. Homogenous experimental assays allowed both direct microbe-mineral and indirect microbe-ion interactions to affect forsterite dissolution rates. Dissolution rates were calculated based on silica concentrations and zero-order dissolution kinetics

  20. Cooling tower

    International Nuclear Information System (INIS)

    Baer, E.; Dittrich, H.; Ernst, G.; Roller, W.

    1975-01-01

    The task on which the invention is based is to design a cooling tower in such a way that the negative influences of the wind, in particular strong side winds (wind velocities of over 10 m/s), on the functioning of the cooling tower are reduced or eliminated altogether. (orig./TK) [de

  1. Influence of angle between the nozzle and skin surface on the heat flux and overall heat extraction during cryogen spray cooling

    International Nuclear Information System (INIS)

    Aguilar, Guillermo; Vu, Henry; Nelson, J Stuart

    2004-01-01

    High speed video imaging and an inverse heat conduction problem algorithm were used to observe and measure the effect of the angle between the nozzle and surface of a skin phantom on: (a) surface temperature; (b) heat flux q; and (c) overall heat extraction Q during cryogen spray cooling (CSC). A skin phantom containing a fast-response temperature sensor was sprayed with 50 ms cryogen spurts from a commercial nozzle placed 30 mm from the surface. The nozzle was systematically positioned at angles ranging from 5 deg. to 90 deg. (perpendicular) with respect to the phantom surface. It is shown that angles as low as 15 deg. have an insignificant impact on the surface temperature, q and Q. Only exaggerated angles of 5 deg. show up to 10% lower q and 30% lower Q with respect to the maximal values measured when nozzles are aimed perpendicularly. This study proves that the slight angle that many commercial nozzles have does not affect significantly the CSC efficiency. (note)

  2. Computation of single- and two-phase heat transfer rates suitable for water-cooled tubes and subchannels

    International Nuclear Information System (INIS)

    Groeneveld, D.C.; Leung, L.K.H.; Cheng, S.C.; Nguyen, C.

    1989-01-01

    A computational method for predicting heat transfer, valid for a wide range of flow conditions (from pool boiling and laminar flow conditions to highly turbulent flow), has been developed. It correctly identifies the heat transfer modes and predicts the heat transfer rates as well as transition points (such as the critical heat flux point) on the boiling curve. The computational heat transfer method consists of a combination of carefully chosen heat transfer equations for each heat transfer mode. Each of these equations has been selected because of their accuracy, wide range of application, and correct asymptotic trends. Using a mechanistically-based heat transfer logic, these equations have been combined in a convenient software package suitable for PC or mainframe application. The computational method has been thoroughly tested against many sets of experimental data. The parametric and asymptotic trends of the prediction method have been examined in detail. Correction factors are proposed for extending the use of individual predictive techniques to various geometric configurations and upstream conditions. (orig.)

  3. Particle-in-cell studies of fast-ion slowing-down rates in cool tenuous magnetized plasma

    Science.gov (United States)

    Evans, Eugene S.; Cohen, Samuel A.; Welch, Dale R.

    2018-04-01

    We report on 3D-3V particle-in-cell simulations of fast-ion energy-loss rates in a cold, weakly-magnetized, weakly-coupled plasma where the electron gyroradius, ρe, is comparable to or less than the Debye length, λDe, and the fast-ion velocity exceeds the electron thermal velocity, a regime in which the electron response may be impeded. These simulations use explicit algorithms, spatially resolve ρe and λDe, and temporally resolve the electron cyclotron and plasma frequencies. For mono-energetic dilute fast ions with isotropic velocity distributions, these scaling studies of the slowing-down time, τs, versus fast-ion charge are in agreement with unmagnetized slowing-down theory; with an applied magnetic field, no consistent anisotropy between τs in the cross-field and field-parallel directions could be resolved. Scaling the fast-ion charge is confirmed as a viable way to reduce the required computational time for each simulation. The implications of these slowing down processes are described for one magnetic-confinement fusion concept, the small, advanced-fuel, field-reversed configuration device.

  4. Second sector cool down

    CERN Multimedia

    2007-01-01

    At the beginning of July, cool-down is starting in the second LHC sector, sector 4-5. The cool down of sector 4-5 may occasionally generate mist at Point 4, like that produced last January (photo) during the cool-down of sector 7-8.Things are getting colder in the LHC. Sector 7-8 has been kept at 1.9 K for three weeks with excellent stability (see Bulletin No. 16-17 of 16 April 2007). The electrical tests in this sector have got opt to a successful start. At the beginning of July the cryogenic teams started to cool a second sector, sector 4-5. At Point 4 in Echenevex, where one of the LHC’s cryogenic plants is located, preparations for the first phase of the cool-down are underway. During this phase, the sector will first be cooled to 80 K (-193°C), the temperature of liquid nitrogen. As for the first sector, 1200 tonnes of liquid nitrogen will be used for the cool-down. In fact, the nitrogen circulates only at the surface in the ...

  5. Cooling clothing utilizing water evaporation

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Tominaga, Naoto; Melikov, Arsen Krikor

    2014-01-01

    We developed cooling clothing that utilizes water evaporation to cool the human body and has a mechanism to control the cooling intensity. Clean water was supplied to the outer surface of the T-shirt of the cooling clothing, and a small fan was used to enhance evaporation on this outer surface...... temperature ranging from 27.4 to 30.7 °C to establish a suitable water supply control method. A water supply control method that prevents water accumulation in the T-shirt and water dribbling was validated; this method is established based on the concept of the water evaporation capacity under the applied...

  6. Far from equilibrium enstatite dissolution rates in alkaline solutions at earth surface conditions

    Science.gov (United States)

    Halder, Sougata; Walther, John V.

    2011-12-01

    Far from equilibrium enstatite dissolution rates both open to atmospheric CO 2 and CO 2 purged were measured as a function of solution pH from 8 to 13 in batch reactors at room temperature. Congruent dissolution was observed after an initial period of incongruent dissolution with preferential Si release from the enstatite. Steady-state dissolution rates in open to atmospheric CO 2 conditions decrease with increase in solution pH from 8 to 12 similar to the behavior reported by other investigators. Judging from the pH 13 dissolution rate, rates increase with pH above pH 12. This is thought to occur because of the increase in overall negative surface charges on enstatite as Mg surface sites become negative above pH 12.4, the pH of zero surface charge of MgO. Steady-state dissolution rates of enstatite increase above pH 10 when CO 2 was purged by performing the experiments in a N 2 atmosphere. This suggests inhibition of dissolution rates above pH 10 when experiments were open to the atmosphere. The dissolved carbonate in these solutions becomes dominantly CO 32- above pH 10.33. It is argued that CO 32- forms a >Mg 2-CO 3 complex at positively charged Mg surface sites on enstatite, resulting in stabilization of the surface Si-O bonds. Therefore, removal of solution carbonate results in an increase in dissolution rates of enstatite above pH 10. The log rate of CO 2-purged enstatite dissolution in moles per cm 2 per s as a function of increasing pH above pH 10 is equal to 0.35. This is consistent with the model of silicate mineral dissolution in the absence of surface carbonation in alkaline solutions proposed earlier in the literature.

  7. Reaction rates of ozone and terpenes adsorbed to model indoor surfaces.

    Science.gov (United States)

    Springs, M; Wells, J R; Morrison, G C

    2011-08-01

    Reaction rates and reaction probabilities have been quantified on model indoor surfaces for the reaction of ozone with two monoterpenes (Δ(3) -carene and d-limonene). Molar surface loadings were obtained by performing breakthrough experiments in a plug-flow reactor (PFR) packed with beads of glass, polyvinylchloride or zirconium silicate. Reaction rates and probabilities were determined by equilibrating the PFR with both the terpene and the ozone and measuring the ozone consumption rate. To mimic typical indoor conditions, temperatures of 20, 25, and 30°C were used in both types of experiments along with a relative humidity ranging from 10% to 80%. The molar surface loading decreased with increased relative humidity, especially on glass, suggesting that water competed with the terpenes for adsorption sites. The ozone reactivity experiments indicate that higher surface loadings correspond with higher ozone uptake. The reaction probability for Δ(3) -carene with ozone ranged from 2.9 × 10(-6) to 3.0 × 10(-5) while reaction probabilities for d-limonene ranged from 2.8 × 10(-5) to 3.0 × 10(-4) . These surface reaction probabilities are roughly 10-100 times greater than the corresponding gas-phase values. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially for lower volatility terpenoids. At present, it is unclear how important heterogeneous reactions will be in influencing indoor concentrations of terpenes, ozone and their reaction products. We observe that surface reaction probabilities were 10 to 100 times greater than their corresponding gas-phase values. Thus indoor surfaces do enhance effective reaction rates and adsorption of terpenes will increase ozone flux to otherwise low-reactivity surfaces. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially

  8. First principles predictions of electron tunneling rates between atoms and crystalline surfaces

    Science.gov (United States)

    Neidfeldt, Keith

    Charge transfer is a critical process that controls many important reactions such as photosynthesis, corrosion, and catalysis. We developed a quantitative method for calculating charge transfer rates using periodic density functional theory (DFT). This approach allows us to model from first principles the interaction between an adsorbate and arbitrary material surfaces. By deconvoluting the projected density of states of the ionization level of the atom, we can determine its width, which is proportional to the charge transfer rate. These rates can be used to predict important properties such as adsorbate excited state lifetimes and neutralization fractions for scattered ions. By comparing neutralization fractions for Li scattering off of Al(001) to experimental data, we validated our first principles method of predicting charge transfer rates. While our results are consistent with the classic Langmuir-Gurney (LG) model of adsorption for nearly-free-electron-like metal surfaces, we find several important deviations caused by the actual electronic structure of more complicated material surfaces. For example, we find that the d-band of transition metal surfaces mediates an intra-atomic hybridization of the Li ionization level. Secondly, we find that surface-projected band gaps (e.g., in Cu(111)) enhance the lifetimes of alkali atoms above surfaces containing such band gaps. In addition, our method allows us to also study atoms interacting with non-metallic surfaces where the LG model does not apply. For example, we find that alkali charge transfer rates are controlled by dangling bonds on covalently-bonded surfaces (e.g., Si(001)-(2xl)) instead of by the traditional image potential.

  9. Electron cooling experiments at Fermilab

    International Nuclear Information System (INIS)

    Forster, R.; Hardek, T.; Johnson, D.E.; Kells, W.; Kerner, V.; Lai, H.; Lennox, A.J.; Mills, F.; Miyahara, Y.; Oleksiuk, L.; Peters, R.; Rhoades, T.; Young, D.; McIntyre, P.M.

    1981-01-01

    A 115 Mev proton beam has been successfully cooled in the Electron Cooling Ring at Fermilab. Initial experiments have measured the longitudinal drag force, transverse damping rate, and equilibrium beam size. The proton beam was cooled by a factor of aproximately 50 in momentum spread in 5 sec, and by a factor of 3 in transverse size in 15 sec. Long term losses were consistent with single scattering from residual gas, with lifetime approximately 1000 sec. Using the measured electron beam temperature T/sub e/.0.8(2) ev, the observed cooling agrees well with expectations from cooling theory. 13 refs

  10. Material Removal Rate, Electrode Wear Rate, and Surface Roughness Evaluation in Die Sinking EDM with Hollow Tool through Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Teepu Sultan

    2014-01-01

    Full Text Available Electrical discharge machining is one of the earliest nontraditional machining, extensively used in industry for processing of parts having unusual profiles with reasonable precision. In the present work, an attempt has been made to model material removal rate, electrode wear rate, and surface roughness through response surface methodology in a die sinking EDM process. The optimization was performed in two steps using one factor at a time for preliminary evaluation and a Box-Behnken design involving three variables with three levels for determination of the critical experimental conditions. Pulse on time, pulse off time, and peak current were changed during the tests, while a copper electrode having tubular cross section was employed to machine through holes on EN 353 steel alloy workpiece. The results of analysis of variance indicated that the proposed mathematical models obtained can adequately describe the performances within the limits of factors being studied. The experimental and predicted values were in a good agreement. Surface topography is revealed with the help of scanning electron microscope micrographs.

  11. Direct Measurement of Surface Dissolution Rates in Potential Nuclear Waste Forms: The Example of Pyrochlore.

    Science.gov (United States)

    Fischer, Cornelius; Finkeldei, Sarah; Brandt, Felix; Bosbach, Dirk; Luttge, Andreas

    2015-08-19

    The long-term stability of ceramic materials that are considered as potential nuclear waste forms is governed by heterogeneous surface reactivity. Thus, instead of a mean rate, the identification of one or more dominant contributors to the overall dissolution rate is the key to predict the stability of waste forms quantitatively. Direct surface measurements by vertical scanning interferometry (VSI) and their analysis via material flux maps and resulting dissolution rate spectra provide data about dominant rate contributors and their variability over time. Using pyrochlore (Nd2Zr2O7) pellet dissolution under acidic conditions as an example, we demonstrate the identification and quantification of dissolution rate contributors, based on VSI data and rate spectrum analysis. Heterogeneous surface alteration of pyrochlore varies by a factor of about 5 and additional material loss by chemo-mechanical grain pull-out within the uppermost grain layer. We identified four different rate contributors that are responsible for the observed dissolution rate range of single grains. Our new concept offers the opportunity to increase our mechanistic understanding and to predict quantitatively the alteration of ceramic waste forms.

  12. Effects of surface orientation, fluid chemistry and mechanical polishing on the variability of dolomite dissolution rates

    Science.gov (United States)

    Saldi, Giuseppe D.; Voltolini, Marco; Knauss, Kevin G.

    2017-06-01

    Recent studies of carbonate surface reactivity have underscored the fundamental variability of dissolution rates and the heterogeneous distribution of the reaction over the mineral surface due to the inhomogeneous distribution of surface energy. Dolomite dissolution rates relative to different cleavage planes (r-planes) and surfaces cut approximately perpendicular to the c-axis (c-planes) were studied at 50 °C as a function of pH (3.4 ≤ pH ≤ 9.0) and solution composition by vertical scanning interferometry (VSI) and atomic force microscopy (AFM), with the aim of providing an estimate of the intrinsic rate variation of dolomite single crystals and describing the surface reaction distribution and the rate controlling mechanisms. Surface normal retreat rates measured under acidic conditions increased linearly with time and were not visibly affected by the parallel increase of surface roughness. Mean total dissolution rates of r-planes decreased by over 200 times from pH 3.4 to pH 9.0 and CO32--rich solutions, whereas corresponding rate variations spanned over 3 orders of magnitude when also c-plane rate distributions were included in the analysis. At acid to near neutral pH, c-planes dissolved ∼ three times faster than the adjoining r-planes but slower at basic pH and high total carbon concentration, displaying a distinctive morphologic evolution in these two regimes. The comparison of polished and unpolished crystals showed that polished cleavage planes dissolved about three times faster than the unpolished counterpart at near neutral to basic conditions, whereas no significant difference in reactivity was observed at pH < 5. Although experimental data and observations indicate a tendency of dolomite faces to reach a low-energy topography over the course of the reaction, the evolution of the entire crystal morphology depends also on the reactivity of edge and corner regions, whose contribution to measured rates is not generally taken into account by laboratory

  13. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state......-of-the-art of ventilative cooling potentials and limitations, its consideration in current energy performance regulations, available building components and control strategies and analysis methods and tools. In addition, the report provides twenty six examples of operational buildings using ventilative cooling ranging from...

  14. Significant cooling effect on the surface due to soot particles over Brahmaputra River Valley region, India: An impact on regional climate

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, S., E-mail: smbtiwari@tropmet.res.in [Indian Institute of Tropical Meteorology, New Delhi Branch, New Delhi 110060 (India); Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm SE-10691 (Sweden); Kumar, R. [Research Application Laboratory, National Center for Atmospheric Research, Boulder, CO (United States); Tunved, P. [Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm SE-10691 (Sweden); Singh, S. [CSIR, Central Institute of Mining & Fuel Research, Dhanbad, Jharkhand 826001 (India); Panicker, A.S. [Indian Institute of Tropical Meteorology, Pune 411008 (India)

    2016-08-15

    Black carbon (BC) is an important atmospheric aerosol constituent that affects the climate by absorbing (directly) the sunlight and modifying cloud characteristics (indirectly). Here, we present first time yearlong measurements of BC and carbon monoxide (CO) from an urban location of Guwahati located in the Brahmaputra River valley (BRV) in the northeast region of India from 1st July 2013 to 30th June 2014. Daily BC concentrations varied within the range of 2.86 to 11.56 μg m{sup −3} with an annual average of 7.17 ± 1.89 μg m{sup −3}{sub ,} while, CO varied from 0.19 to 1.20 ppm with a mean value of 0.51 ± 0.19 ppm during the study period. The concentrations of BC (8.37 μg m{sup −3}) and CO (0.67 ppm) were ~ 39% and ~ 55% higher during the dry months (October to March) than the wet months (April to September) suggesting that seasonal changes in meteorology and emission sources play an important role in controlling these species. The seasonal ΔBC/ΔCO ratios were highest (lowest) in the pre-monsoon (winter) 18.1 ± 1.4 μg m{sup −3} ppmv{sup −1} (12.6 ± 2.2 μg m{sup −3} ppmv{sup −1}) which indicate the combustion of biofuel/biomass as well as direct emissions from fossil fuel during the pre-monsoon season. The annual BC emission was estimated to be 2.72 Gg in and around Guwahati which is about 44% lower than the mega city ‘Delhi’ (4.86 Gg). During the study period, the annual mean radiative forcing (RF) at the top of the atmosphere (TOA) for clear skies of BC was + 9.5 Wm{sup −2}, however, the RF value at the surface (SFC) was − 21.1 Wm{sup −2} which indicates the net warming and cooling effects, respectively. The highest RF at SFC was in the month of April (− 30 Wm{sup −2}) which is coincident with the highest BC mass level. The BC atmospheric radiative forcing (ARF) was + 30.16 (annual mean) Wm{sup −2} varying from + 23.1 to + 43.8 Wm{sup −2}. The annual mean atmospheric heating rate (AHR) due to the BC aerosols was 0.86 K

  15. Enhancement of Natural Convection by Carbon Nanotube Films Covered Microchannel-Surface for Passive Electronic Cooling Devices.

    Science.gov (United States)

    Zhang, Guang; Jiang, Shaohui; Yao, Wei; Liu, Changhong

    2016-11-16

    Owing to the outstanding properties of thermal conduction, lightweight, and chemical durability, carbon nanotubes (CNTs) have revealed promising applications in thermal management materials. Meanwhile, the increasingly popular portable electronics and the rapid development of space technology need lighter weight, smaller size, and more effective thermal management devices. Here, a novel kind of heat dissipation devices based on the superaligned CNT films and underlying microchannels is proposed, and the heat dissipation properties are measured at the natural condition. Distinctive from previous studies, by combining the advantages of microchannels and CNTs, such a novel heat dissipation device enables superior natural convection heat transfer properties. Our findings prove that the novel CNT-based devices could show an 86.6% larger total natural heat dissipation properties than bare copper plate. Further calculations of the radiation and natural convection heat transfer properties demonstrate that the excellent passive cooling properties of these CNT-based devices are primarily caused by the reinforcement of the natural convection heat transfer properties. Furthermore, the heat dissipation mechanisms are briefly discussed, and we propose that the very high heat transfer coefficients and the porous structures of superaligned CNT films play critical roles in reinforcing the natural convection. The novel CNT-based heat dissipation devices also have advantages of energy-saving, free-noise, and without additional accessories. So we believe that the CNT-based heat dissipation devices would replace the traditional metal-finned heat dissipation devices and have promising applications in electronic devices, such as photovoltaic devices, portable electronic devices, and electronic displays.

  16. A directly cooled grating substrate for ALS [Advanced Light Source] undulator beam lines

    International Nuclear Information System (INIS)

    DiGennaro, R.; Swain, T.

    1989-08-01

    Design analyses using finite element methods are presented for thermal distortion of water-cooled diffraction grating substrates for a potential application at the LBL Advanced Light Source, demonstrating that refinements in cooling channel configuration and heat flux distribution can significantly reduce optical surface distortion with high heat loads. Using an existing grating substrate design, sensitivity of tangential slope errors due to thermal distortion is evaluated for a variety of thermal boundary conditions, including coolant flow rate and heat transfer film coefficients, surface illumination area and heat distribution profile, and location of the convection cooling surfaces adjacent to the heated region. 1 ref., 5 figs., 2 tabs

  17. Results from IODP Leg 306: Long-term cooling trend in North Atlantic sea-surface temperatures during the last 5 Ma

    Science.gov (United States)

    Naafs, David; Hefter, Jens; Stein, Ruediger; Haug, Gerald

    2010-05-01

    In the early Pliocene global surface temperatures were several degrees warmer than today and ice sheets in the Northern Hemisphere had a limited extent [e.g., Haywood et al., 2005; Zachos et al., 2001]. This changed during the intensification of Northern Hemisphere glaciation (INHG) between 3.4 and 2.5 Ma (with a major step around 2.7 Ma), when global climate cooled and ice sheets in the Northern Hemisphere became more extensive [e.g., Zachos et al., 2001]. Here we present results from the first orbitally resolved (~ 4 ka resolution) record of Uk'37 based sea-surface temperature (SST) in the North Atlantic spanning the last 5 Ma. We used samples from the recently drilled IODP Site U1313, which is located in the North Atlantic at 41 oN and is a re-drill of DSDP Site 607. Our results show that the long-term cooling of SST in the North Atlantic began in the Early Pliocene around 4.1 Ma, which is earlier than previously thought. During the Pleistocene SST continued to cool and at the beginning of the mid-Pleistocene transition (MIS 40) glacial SST show a sudden drop to temperatures comparable to the LGM. At the same time the C37:4 alkenone, an indicator for arctic water masses [e.g., McClymont et al., 2008], became more abundant. We relate this to the influence of Arctic waters reaching far into the North Atlantic as the Arctic Front moved south during the peak glacial conditions of the Middle to Late Pleistocene. References: Haywood, A. M., P. Dekens, A. C. Ravelo, and M. Williams (2005), Warmer tropics during the mid-Pliocene? Evidence from alkenone paleothermometry and a fully coupled ocean-atmosphere GCM, Geochem. Geophys. Geosyst., 6(3), doi:10.1029/2004GC000799. McClymont, E. L., A. Rosell-Melé, G. H. Haug, and J. M. Lloyd (2008), Expansion of subarctic water masses in the North Atlantic and Pacific oceans and implications for mid-Pleistocene ice sheet growth, Paleoceanography, 23. Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups (2001), Trends

  18. Steady and dynamic shear rheological behavior of semi dilute Alyssum homolocarpum seed gum solutions: influence of concentration, temperature and heating-cooling rate.

    Science.gov (United States)

    Alaeddini, Behzad; Koocheki, Arash; Mohammadzadeh Milani, Jafar; Razavi, Seyed Mohammad Ali; Ghanbarzadeh, Babak

    2017-10-30

    Alyssum homolocarpum seed gum (AHSG) solution exhibits high viscosity at low shear rates and has anionic features. However there is no information regarding the flow and dynamic properties of this gum in semi-dilute solutions. The present study aimed to investigate the dynamic and steady shear behavior of AHSG in the semi-dilute region. The viscosity profile demonestrated a shear thinning behavior at all temperatures and concentrations. An increase in the AHSG concentration was acompanied by an increase in the pseudoplasticity degree, whereas, by increasing the temperature, the pseudoplasticity of AHSG decreased. At low gum concentration, solutions had more viscosity dependence on temperature. The mechanical spectra obtained from the frequency sweep experiment demonstrated viscoelastic properties for gum solutions. AHSG solutions showed typical weak gel-like behavior, revealing G' greater than G' within the experimental range of frequency (Hz), with slight frequency dependency. The influence of temperature on viscoelastic properties of AHSG solutions was studied during both heating (5-85 °C) and cooling (85-5 °C) processes. The complex viscosity of AHSG was greater compared to the apparent viscosity, indicating the disruption of AHSG network structure under continuous shear rates and deviation from the Cox-Merz rule. During the initial heating, the storage modulus showed a decreasing trend and, with a further increase in temperature, the magnitude of storage modulus increased. The influence of temperature on the storage modulus was considerable when a higher heating rate was applied. AHSG can be applied as a thickening and stabilizing agents in food products that require good stability against temperature. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  19. Distribution of a pelagic tunicate, Salpa fusiformis in warm surface current of the eastern Korean waters and its impingement on cooling water intakes of Uljin nuclear power plant.

    Science.gov (United States)

    Chae, Jinho; Choi, Hyun Woo; Lee, Woo Jin; Kim, Dongsung; Lee, Jae Hac

    2008-07-01

    Impingement of a large amount of gelatinous plankton, Salpa fusiformis on the seawater intake system-screens in a nuclear power plant at Uljin was firstly recorded on 18th June 2003. Whole amount of the clogged animals was estimated were presumptively at 295 tons and the shortage of cooling seawater supply by the animal clogging caused 38% of decrease in generation capability of the power plant. Zooplankton collection with a multiple towing net during the day and at night from 5 to 6 June 2003 included various gelatinous zooplanktons known to be warm water species such as salps and siphonophores. Comparatively larger species, Salpa fusiformis occupied 25.4% in individual density among the gelatinous plankton and showed surface distribution in the depth shallower than thermocline, performing little diel vertical migration. Temperature, salinity and satellite data also showed warm surface current predominated over the southern coastal region near the power plant in June. The results suggested that warm surface current occasionally extended into the neritic region may transfer S. fusiformis, to the waters off the power plant. The environmental factors and their relation to ecobiology of the large quantity of salpa population that are being sucked into the intake channel of the power plant are discussed.

  20. The influence of curvature on film cooling performance

    Science.gov (United States)

    Schwarz, S. G.; Goldstein, R. J.; Eckert, E. R. G.

    1990-06-01

    The effects of injection rate and strength of curvature on film cooling performance of gas injected through a row of holes on a convex surface is studied. Comparisons are made to film cooling of concave and flat surfaces. Three different relative strengths of curvature (ratio of radius of curvature to radius of injection hole), two density ratios (0.95 and 2.0), and a wide range of blowing rates (0.3 to 2.7) are considered. A foreign gas injection technique (mass transfer analogy) is used. The strength of curvature was controlled by varying the injection hole diameter. At low blowing rates, film cooling is more effective on the convex surface than on a flat or a concave surface. The cross stream pressure gradient present in curved flows tends to push the jet into the convex wall. As the injection rate is increased, normal and tangential jet momentum promote lift-off from the convex surface, thereby lowering performance. In contrast, previous studies show that a concave surface, tangential jet momentum, flow instabilities, and blockage improve performance on a concave surface as blowing rate is increased.

  1. Prediction of material removal rate and surface roughness for wire electrical discharge machining of nickel using response surface methodology

    Directory of Open Access Journals (Sweden)

    Thangam Chinnadurai

    2016-12-01

    Full Text Available This study focuses on investigating the effects of process parameters, namely, Peak current (Ip, Pulse on time (Ton, Pulse off time (Toff, Water pressure (Wp, Wire feed rate (Wf, Wire tension (Wt, Servo voltage (Sv and Servo feed setting (Sfs, on the Material Removal Rate (MRR and Surface Roughness (SR for Wire electrical discharge machining (Wire-EDM of nickel using Taguchi method. Response Surface Methodology (RSM is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used.

  2. Prediction of material removal rate and surface roughness for wire electrical discharge machining of nickel using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Chinnadurai, T.; Vendan, S.A.

    2016-07-01

    This study focuses on investigating the effects of process parameters, namely, Peak current (Ip), Pulse on time (Ton), Pulse off time (Toff), Water pressure (Wp), Wire feed rate (Wf), Wire tension (Wt), Servo voltage (Sv) and Servo feed setting (Sfs), on the Material Removal Rate (MRR) and Surface Roughness (SR) for Wire electrical discharge machining (Wire-EDM) of nickel using Taguchi method. Response Surface Methodology (RSM) is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA) method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used. (Author)

  3. Forcing Mechanisms for the Variations of Near-surface Temperature Lapse Rates along the Himalayas, Tibetan Plateau (HTP) and Their Surroundings

    Science.gov (United States)

    Kattel, D. B.; Yao, T.; Ullah, K.; Islam, G. M. T.

    2016-12-01

    This study investigates the monthly characteristics of near-surface temperature lapse rates (TLRs) (i.e., governed by surface energy balance) based on the 176 stations 30-year (1980 to 2010) dataset covering a wide range of topography, climatic regime and relief (4801 m) in the HTP and its surroundings. Empirical analysis based on techniques in thermodynamics and hydrostatic system were used to obtain the results. Steepest TLRs in summer is due to strong dry convection and shallowest in winter is due to inversion effect is the general pattern of TLR that reported in previous studies in other mountainous region. Result of this study reports a contrast variation of TLRs from general patterns, and suggest distinct forcing mechanisms in an annual cycle. Shallower lapse rate occurs in summer throughout the regions is due to strong heat exchange process within the boundary layer, corresponding to the warm and moist atmospheric conditions. There is a systematic differences of TLRs in winter between the northern and southern slopes the Himalayas. Steeper TLRs in winter on the northern slopes is due to intense cooling at higher elevations, corresponding to the continental dry and cold air surges, and considerable snow-temperature feedback. The differences in elevation and topography, as well as the distinct variation of turbulent heating and cooling, explain the contrast TLRs (shallower) values in winter on the southern slopes. Distinct diurnal variations of TLRs and its magnitudes between alpine, dry, humid and coastal regions is due to the variations of adiabatic mixing during the daytime in the boundary layer i.e., associated with the variations in net radiations, elevation, surface roughness and sea surface temperature. The findings of this study is useful to determine the temperature range for accurately modelling in various field such as hydrology, glaciology, ecology, forestry, agriculture, as well as inevitable for climate downscaling in complex mountainous terrain.

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

    Science.gov (United States)

    Boutron, P

    1984-04-01

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

  5. Local cooling effect on perforation rates comparing the 980-1470 nm laser wavelengths used with endovenous laser ablation: double blind in vitro experimental study.

    Science.gov (United States)

    Tarhan, I A; Dumantepe, M; Yurdakul, I; Kehlibar, T; Ozler, A

    2014-03-01

    Endovenous laser treatment (EVLA) is fast gaining acceptance as an alternative to open surgery for the treatment of saphenous vein incompetence. The method of action of these techniques is based on heat, making tumescence anaesthesia necessity. Heat-induced complications may occur with inadequate application of tumescent anaesthesia. Our hypothesis was, local cooling effect of tumescent anaesthesia on tunica adventitia might be kept undamaged from disruption due to the thermal injury. We experimented with two popular laser wavelengths (980 and 1470 nm) and with two different thermal media (+4 and +24) in vitro for perforation. Twenty different 12 cm length vein pieces were numbered randomly to set up four groups of the experiment. Endovenous laser procedures were applied in same manner in a unique design test tube with same energy density per pieces on same duration (10 W/second) (linear endovenous energy density 60 J/cm). Procedure video was recorded for macroscopic perforations. All postprocedure vein segments were examined microscopically. Activities of both wavelengths were much better in cold medium (P laser was better than that of 980 nm in cold environment (P = 0.0136). It can be commented that reducing the ambient temperature is more beneficial than modifying the laser wavelength on perforation rates. Therefore we suppose tumescent anaesthesia temperature is effective on perforation independently from the wavelengths or type of the laser fibre.

  6. Analysis of antiphase domain growth in ternary FeCo alloys after different cooling rates and annealing treatments using neutron diffraction and positron annihilation

    International Nuclear Information System (INIS)

    Gilles, Ralph; Hofmann, Michael; Johnson, Francis; Gao Yan; Mukherji, Debashis; Hugenschmidt, Christoph; Pikart, Philip

    2011-01-01

    Research highlights: → In-situ observation at high temperatures of atomic position change Fe and Co with neutron diffraction. → Determination of antiphase domain growth with neutron diffraction. → Determination of vacacny defects at antiphase domain boundaries with positron annihilation. → Combination of neutron diffraction and positron annihilation to correlate ordering/disordering process and the defect density of ternary FeCo alloys. - Abstract: FeCo alloys are industrially important engineering materials which play an outstanding role in applications requiring soft magnetic materials. The challenge is to include ternary elements to improve the mechanical properties. Here noble elements as Pt or Pd were used for these experiments. With neutron diffraction and positron annihilation technique Fe 67 Co 30 Pt 3 and Fe 67 Co 30 Pd 3 (at. pct.) samples were measured to study the influence of different cooling rates on ordering and disordering. The ordering and disordering process is responsible for the mechanical properties in dependence of temperature. The correlation of ordering and defect density is described.

  7. Is there a link between blastomere contact surfaces of day 3 embryos and live birth rate?

    Directory of Open Access Journals (Sweden)

    Paternot Goedele

    2012-09-01

    Full Text Available Abstract Background Cell-cell communication and adhesion are essential for the compaction process of early stage embryos. The aim of this study was to develop a non-invasive objective calculation system of embryo compaction in order to test the hypothesis that embryos with a larger mean contact surface result in a higher live birth rate compared to embryos with a lower mean contact surface. Methods Multilevel images of 474 embryos transferred on day 3 were evaluated by the Cellify software. This software calculates the contact surfaces between the blastomeres. The primary outcome of this study was live birth. An ideal range of contact surface was determined and the positive and negative predictive value, the sensitivity, the specificity and the area under the curve for this new characteristic were calculated. Results In total, 115 (24% transferred embryos resulted in a live birth. Selection of an embryo for transfer on its mean contact surface could predict live birth with a high sensitivity (80% and high negative predicting value (83% but with a low positive predictive value (27%, a low specificity (31% and low area under the ROC curve (0.56. The mean contact surface of embryos cultured in a single medium was significantly higher compared to the mean contact surface of embryos cultured in a sequential medium (p = 0.0003. Conclusions Neither the mean contact surface nor the number of contact surfaces of a day 3 embryo had an additional value in the prediction of live birth. The type of culture medium, however, had an impact on the contact surface of an embryo. Embryos cultured in a single medium had a significant larger contact surface compared to embryos cultured in the sequential medium.

  8. The effect of loading rate on ductile fracture toughness and fracture surface roughness

    DEFF Research Database (Denmark)

    Osovski, S.; Srivastava, Akhilesh Kumar; Ponson, L.

    2015-01-01

    The variation of ductile crack growth resistance and fracture surface roughness with loading rate is modeled under mode I plane strain, small scale yielding conditions. Three-dimensional calculations are carried out using an elastic-viscoplastic constitutive relation for a progressively cavitatin...

  9. Lunar floor-fractured craters: Modes of dike and sill emplacement and implications of gas production and intrusion cooling on surface morphology and structure

    Science.gov (United States)

    Wilson, Lionel; Head, James W.

    2018-05-01

    within ∼300 m of the surface, and thus eruptions, rather than intrusions, would be very likely to occur; instead, dynamical considerations strongly favor the sub-crustal breccia lens as the location of the physical property contrast localizing lateral intrusion, at a depth of several kilometers. The end of lateral and vertical sill growth occurs when the internal magma pressure equals the external pressure (the intrusion just supports the weight of the overlying crust). Dynamical considerations lead to the conclusion that dike magma volumes are up to ∼1100 km3, and are generally insufficient to form FFCs on the lunar farside; the estimated magma volumes available for injection into sills on the lunar nearside (up to ∼800 km3) are comparable to the observed floor uplift in many smaller FFCs, and thus consistent with these FFCs forming from a single dike emplacement event. In contrast, the thickest intrusions in the largest craters imply volumes requiring multiple dike contributions; these are likely to be events well-separated in time, rather than injection of new magma into a recently-formed and still-cooling intrusion. We present a temporal sequence of 1) dike emplacement, 2) sill formation and surface deformation, 3) bubble rise, foam layer formation and collapse, 4) intrusion cooling, and a synthesis of predicted deformation sequence and eruption styles. Initial lateral injection of the sill at a depth well below the upper dike tip initiates upbowing of the overburden, leveraging deformation of the crater floor melt sheet above. This is followed by lateral spreading of the sill toward the edges of the crater floor, where crater wall and rim deposit overburden inhibit further lateral growth, and the sill grows vertically into a laccolith or bysmalith, uplifting the entire floor above the intrusion. Subsidiary dikes can be emplaced in the fractures at the uplift margins and will rise to the isostatic level of the initial dike tip; if these contain sufficient

  10. Dissociation and recombination rate constants for CN on Cu and Ni group transition metal surfaces

    Science.gov (United States)

    Sellers, Harrell

    2000-07-01

    We report dissociation and recombination reaction rate constants for CN on the fcc(111) surfaces of Ni, Pd, Pt, Cu, Ag and Au from molecular dynamics simulations employing our normalized bond index-reactive potential functions (NBI-RPF). The Arrhenius pre-exponentials for recombination of CN on these surfaces are about three orders of magnitude greater than the dissociation pre-exponentials. On the series of metals considered herein, the reaction energetics favor dissociation on the more active metals and favor recombination on the least active metals. However, the differences in the pre-exponentials of nearly a factor of 10 3 express the tendency of the reaction entropy to favor the recombination on the surfaces investigated. We also discuss the implications of these results in terms of the thermodynamics of the surface reactions.

  11. First-order dissolution rate law and the role of surface layers in glass performance assessment

    Science.gov (United States)

    Grambow, B.; Müller, R.

    2001-09-01

    The first-order dissolution rate law is used for nuclear waste glass performance predictions since 1984. A first discussion of the role of saturation effects was initiated at the MRS conference that year. In paper (1) it was stated that "For glass dissolution A* (the reaction affinity) cannot become zero since saturation only involves the reacting surface while soluble elements still might be extracted from the glass" [B. Grambow, J. Mater. Res. Soc. Symp. Proc. 44 (1985) 15]. Saturation of silica at the surface and condensation of surface silanol groups was considered as being responsible for the slow down of reaction rates by as much as a factor of 1000. Precipitation of Si containing secondary phases such as quartz was invoked as a mechanism for keeping final dissolution affinities higher than zero. Another (2) paper [A.B. Barkatt, P.B. Macedo, B.C. Gibson, C.J. Montrose, J. Mater. Res. Soc. Symp. Proc. 44 (1985) 3] stated that "… under repository conditions the extent of glass dissolution will be moderate due to saturation with respect to certain major elements (in particular, Si, Al and Ca). Consequently, the concentration levels of the more soluble glass constituents in the aqueous medium are expected to fall appreciable below their solubility limit." The formation of dense surface layers was considered responsible for explaining the saturation effect. The mathematical model assumed stop of reaction in closed systems, once solubility limits were achieved. For more than 15 years the question of the correctness of one or the other concept has seldom been posed and has not yet been resolved. The need of repository performance assessment for validated rate laws demands a solution, particularly since the consequences of the two concepts and research requirements for the long-term glass behavior are quite different. In concept (1) the stability of the `equilibrium surface region' is not relevant because, by definition, this region is stable chemically and after a

  12. Surface controlled dissolution rates of gypsum in aqueous solutions exhibit nonlinear dissolution kinetics

    Science.gov (United States)

    Jeschke, Alexander A.; Vosbeck, Katrin; Dreybrodt, Wolfgang

    2001-01-01

    The effective dissolution rates of gypsum are determined by mixed kinetics, where the rate constants of dissolution at the surface and the transport constant of molecular diffusion of dissolved material are similar. To obtain the surface reaction rate law it is necessary to know the transport constant. We have determined the surface rate law for monocrystalline selenite by using a rotating disc set-up, where the transport coefficients are well known. As a result, up to a calcium concentration of 0.6 · ceq, we find a nearly linear rate law Rs = ksl (1- cs/ ceq) n1, where cs is the total calcium concentration at the surface and ceq the equilibrium concentration with respect to gypsum, n1 = 1.2 ± 0.2, and ksl = 1.1 · 10 -4 mmol cm -2 s -1 ± 15%. We also employed batch-experiments for selenite, alabaster and gypsum rock samples. The result of these experiments were interpreted by using a transport constant determined by NaCl dissolution experiments under similar physical conditions. The batch experiments reveal a dissolution rate law Rs = ksl (1- cs/ ceq) n1, ksl = 1.3 · 10 -4 mmol · cm -2 s -1, n1 = 1.2 ± 0.2 for c ≤ 0.94 · ceq. Close to equilibrium a nonlinear rate law, Rs = ks2 (1- cs/ ceq) n2, is observed, where ks2 is in the order of 10 mmol · cm -2 s -1 and n2 ≈ 4.5. The experimentally observed gypsum dissolution rates from the batch experiments could be accurately fitted, with only minor variations of the surface reaction constant obtained from the rotating disk experiment and the transport coefficient from the NaCl dissolution batch experiment. Batch experiments on pure synthetic gypsum, reveal a linear rate law up to equilibrium. This indicates inhibition of dissolution in natural samples close to equilibrium, as is known also for calcite minerals.

  13. Open charcoal chamber method for mass measurements of radon exhalation rate from soil surface

    International Nuclear Information System (INIS)

    Tsapalov, Andrey; Kovler, Konstantin; Miklyaev, Peter

    2016-01-01

    Radon exhalation rate from the soil surface can serve as an important criterion in the evaluation of radon hazard of the land. Recently published international standard ISO 11665-7 (2012) is based on the accumulation of radon gas in a closed container. At the same time since 1998 in Russia, as a part of engineering and environmental studies for the construction, radon flux measurements are made using an open charcoal chamber for a sampling duration of 3–5 h. This method has a well-defined metrological justification and was tested in both favorable and unfavorable conditions. The article describes the characteristics of the method, as well as the means of sampling and measurement of the activity of radon absorbed. The results of the metrological study suggest that regardless of the sampling conditions (weather, the mechanism and rate of radon transport in the soil, soil properties and conditions), uncertainty of method does not exceed 20%, while the combined standard uncertainty of radon exhalation rate measured from the soil surface does not exceed 30%. The results of the daily measurements of radon exhalation rate from the soil surface at the experimental site during one year are reported. - Highlights: • Radon exhalation rate from the soil surface area of 32 cm 2 can be measured at level of 10 mBq/(m 2 s) at the uncertainty ≤30%. • The method has a metrological justification. • No need to consider climate conditions, soil properties and conditions, mechanism and rate of radon transport in the soil.

  14. Active cooling of a mobile phone handset

    International Nuclear Information System (INIS)

    Grimes, Ronan; Walsh, Ed; Walsh, Pat

    2010-01-01

    Power dissipation levels in mobile phones continue to increase due to gaming, higher power applications, and increased functionality associated with the internet. The current cooling methodologies of natural convection and radiation limit the power dissipation within a mobile phone to between 1-2 W depending on size. As power dissipation levels increase, products such as mobile phones will require active cooling to ensure that the devices operate within an acceptable temperature envelop from both user comfort and reliability perspectives. In this paper, we focus on the applied thermal engineering problem of an active cooling solution within a typical mobile phone architecture by implementing a custom centrifugal fan within the mobile phone. Its performance is compared in terms of flow rates and pressure drops, allowable phone heat dissipation and maximum phone surface temperature as this is the user constraint for a variety of simulated PCB architectures in the mobile phone. Perforated plates with varying porosity through different size orifices are used to simulate these architectures. The results show that the power level dissipated by a phone for a constant surface temperature may be increased by ∼50 - 75% depending on pressure drop induced by the internal phone architecture. Hence for successful implementation and efficient utilization of active cooling will require chip layout to be considered at the design stage.

  15. Cooling water requirements and nuclear power plants

    International Nuclear Information System (INIS)

    Rao, T.S.

    2010-01-01

    Indian nuclear power programme is poised to scuttle the energy crisis of our time by proposing joint ventures for large power plants. Large fossil/nuclear power plants (NPPs) rely upon water for cooling and are therefore located near coastal areas. The amount of water a power station uses and consumes depends on the cooling technology used. Depending on the cooling technology utilized, per megawatt existing NPPs use and consume more water (by a factor of 1.25) than power stations using other fuel sources. In this context the distinction between 'use' and 'consume' of water is important. All power stations do consume some of the water they use; this is generally lost as evaporation. Cooling systems are basically of two types; Closed cycle and Once-through, of the two systems, the closed cycle uses about 2-3% of the water volumes used by the once-through system. Generally, water used for power plant cooling is chemically altered for purposes of extending the useful life of equipment and to ensure efficient operation. The used chemicals effluent will be added to the cooling water discharge. Thus water quality impacts on power plants vary significantly, from one electricity generating technology to another. In light of massive expansion of nuclear power programme there is a need to develop new ecofriendly cooling water technologies. Seawater cooling towers (SCT) could be a viable option for power plants. SCTs can be utilized with the proper selection of materials, coatings and can achieve long service life. Among the concerns raised about the development of a nuclear power industry, the amount of water consumed by nuclear power plants compared with other power stations is of relevance in light of the warming surface seawater temperatures. A 1000 MW power plant uses per day ∼800 ML/MW in once through cooling system; while SCT use 27 ML/MW. With the advent of new marine materials and concrete compositions SCT can be constructed for efficient operation. However, the

  16. ISM stripping from cluster galaxies and inhomogeneities in cooling flows

    Science.gov (United States)

    Soker, Noam; Bregman, Joel N.; Sarazin, Craig L.

    1990-01-01

    Analyses of the x ray surface brightness profiles of cluster cooling flows suggest that the mass flow rate decreases towards the center of the cluster. It is often suggested that this decrease results from thermal instabilities, in which denser blobs of gas cool rapidly and drop below x ray emitting temperatures. If the seeds for the thermal instabilities are entropy perturbations, these perturbations must enter the flow already in the nonlinear regime. Otherwise, the blobs would take too long to cool. Here, researchers suggest that such nonlinear perturbations might start as blobs of interstellar gas which are stripped out of cluster galaxies. Assuming that most of the gas produced by stellar mass loss in cluster galaxies is stripped from the galaxies, the total rate of such stripping is roughly M sub Interstellar Matter (ISM) approx. 100 solar mass yr(-1). It is interesting that the typical rates of cooling in cluster cooling flows are M sub cool approx. 100 solar mass yr(-1). Thus, it is possible that a substantial portion of the cooling gas originates as blobs of interstellar gas stripped from galaxies. The magnetic fields within and outside of the low entropy perturbations can help to maintain their identities, both by suppressing thermal conduction and through the dynamical effects of magnetic tension. One significant question concerning this scenario is: Why are cooling flows seen only in a fraction of clusters, although one would expect gas stripping to be very common. It may be that the density perturbations only survive and cool efficiently in clusters with a very high intracluster gas density and with the focusing effect of a central dominant galaxy. Inhomogeneities in the intracluster medium caused by the stripping of interstellar gas from galaxies can have a number of other effects on clusters. For example, these density fluctuations may disrupt the propagation of radio jets through the intracluster gas, and this may be one mechanism for producing Wide

  17. Hot gas path component cooling system

    Science.gov (United States)

    Lacy, Benjamin Paul; Bunker, Ronald Scott; Itzel, Gary Michael

    2014-02-18

    A cooling system for a hot gas path component is disclosed. The cooling system may include a component layer and a cover layer. The component layer may include a first inner surface and a second outer surface. The second outer surface may define a plurality of channels. The component layer may further define a plurality of passages extending generally between the first inner surface and the second outer surface. Each of the plurality of channels may be fluidly connected to at least one of the plurality of passages. The cover layer may be situated adjacent the second outer surface of the component layer. The plurality of passages may be configured to flow a cooling medium to the plurality of channels and provide impingement cooling to the cover layer. The plurality of channels may be configured to flow cooling medium therethrough, cooling the cover layer.

  18. Theory of tapered laser cooling

    International Nuclear Information System (INIS)

    Okamoto, Hiromi; Wei, J.

    1998-01-01

    A theory of tapered laser cooling for fast circulating ion beams in a storage ring is constructed. The authors describe the fundamentals of this new cooling scheme, emphasizing that it might be the most promising way to beam crystallization. The cooling rates are analytically evaluated to study the ideal operating condition. They discuss the physical implication of the tapering factor of cooling laser, and show how to determine its optimum value. Molecular dynamics method is employed to demonstrate the validity of the present theory

  19. Measurement of the radon exhalation rate from the medium surface by tracing the radon concentration

    International Nuclear Information System (INIS)

    Yanliang Tan; Detao Xiao

    2013-01-01

    The paper will present a method based on the accumulation chamber technique for measuring of radon exhalation from the medium surface. A radon monitor traces the change of radon concentration in the accumulation chamber, and then the radon exhalation can be obtained accurately through linear fit. Based on our recent experiments, the radon exhalation rate from the medium surface obtained from this method is in good agreement with the actual exhalation rate of our simulation facility. This method is superior to the competition method which obtains the radon exhalation through the exponential fit by an external PC-system. The calculation for the exponential fit is very easy by computer and related software. However, for portable instruments, the single chip microcomputer can't calculate the exponential fit rapidly. Thus, this method is usable for developing the new portable instrument to classify building materials, etc. (author)

  20. Erosion in radial inflow turbines. Volume 4: Erosion rates on internal surfaces

    Science.gov (United States)

    Clevenger, W. B., Jr.; Tabakoff, W.

    1975-01-01

    An analytic study of the rate at which material is removed by ingested dust impinging on the internal surfaces of a typical radial inflow turbine is presented. Results show that there are several regions which experience very severe erosion loss, and other regions that experience moderate levels of erosion loss: (1) the greatest amount of material loss occurs on the trailing edges of the nozzle blades where very high velocity, moderate angle impacts occur. The tip regions of ductile materials are also subjected to serious levels of erosion loss; (2) moderate amounts of erosion occur near the end of the scroll and on a few of the nozzle blades near this location. Results are presented in the form of surface contours that exist on the scroll and blade surfaces after continuous particulate ingestion with time.

  1. A very cool cooling system

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    The NA62 Gigatracker is a jewel of technology: its sensor, which delivers the time of the crossing particles with a precision of less than 200 picoseconds (better than similar LHC detectors), has a cooling system that might become the precursor to a completely new detector technique.   The 115 metre long vacuum tank of the NA62 experiment. The NA62 Gigatracker (GTK) is composed of a set of three innovative silicon pixel detectors, whose job is to measure the arrival time and the position of the incoming beam particles. Installed in the heart of the NA62 detector, the silicon sensors are cooled down (to about -20 degrees Celsius) by a microfluidic silicon device. “The cooling system is needed to remove the heat produced by the readout chips the silicon sensor is bonded to,” explains Alessandro Mapelli, microsystems engineer working in the Physics department. “For the NA62 Gigatracker we have designed a cooling plate on top of which both the silicon sensor and the...

  2. Measuring the Electrode Kinetics of Surface Confined Electrode Reactions at a Constant Scan Rate

    OpenAIRE

    Guziejewski, Dariusz; Mirceski, Valentin; Jadresko, Dijana

    2014-01-01

    Abstract: The kinetics of surface confined electrode reactions of alizarin, vitamin B12, and vitamin K2 is measured with square-wave voltammetry over a wide pH interval, by applying the recent methodology for kinetic analysis at a constant scan rate [V. Mirceski, D. Guziejewski, K. Lisichkov, Electrochim. Acta 2013, 114, 667–673]. The reliability and the simplicity of the recent methodology is confirmed. The methodology requires analysis of the peak potential separation o...

  3. Bioaerosol deposition on an air-conditioning cooling coil

    Science.gov (United States)

    Wu, Yan; Chen, Ailu; Luhung, Irvan; Gall, Elliott T.; Cao, Qingliang; Chang, Victor Wei-Chung; Nazaroff, William W.

    2016-11-01

    This study is concerned with the role of a fin-and-tube heat exchanger in modifying microbial indoor air quality. Specifically, depositional losses of ambient bioaerosols and particles onto dry (not cooled) and wet (cool) coil surfaces were measured for different airspeeds passing through the test coil. Total, bacterial and fungal DNA concentrations in condensate water produced by a wet coil were also quantified by means of fluorescent dsDNA-binding dye and qPCR assays. Results revealed that the deposition of bioaerosols and total particles is substantial on coil surfaces, especially when wet and cool. The average deposition fraction was 0.14 for total DNA, 0.18 for bacterial DNA and 0.22 for fungal DNA on the dry coil, increasing to 0.51 for total DNA, 0.50 for bacterial DNA and 0.68 for fungal DNA on the wet coil. Overall, as expected, deposition fractions increased with increasing particle size and increasing airspeed. Deposited DNA was removed from the cooling coil surfaces through the flow of condensing water at a rate comparable to the rate of direct deposition from air. A downward trend of bacterial and fungal DNA measured in condensate water over time provides suggestive evidence of biological growth on heat exchangers during nonoperational times of a ventilation system. This investigation provides new information about bioaerosol deposition onto a conventional fin-and-tube cooling coil, a potentially important factor influencing indoor exposure to microbial aerosols in air-conditioned buildings.

  4. Characterization of MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces

    Directory of Open Access Journals (Sweden)

    Venkatakrishnan Krishnan

    2011-01-01

    Full Text Available Abstract In this study, MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces under ambient condition were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction analysis (XRD, and X-ray photoelectron spectroscopy (XPS. The radiation fluence used was 0.5 J/cm2 at a pulse repetition rate of 25 MHz with 1 ms interaction time. SEM analysis of the irradiated surfaces showed self-assembled intermingled weblike nanofibrous structure in and around the laser-irradiated spots. Further TEM investigation on this nanostructure revealed that the nanofibrous structure is formed due to aggregation of Au-Si/Si nanoparticles. The XRD peaks at 32.2°, 39.7°, and 62.5° were identified as (200, (211, and (321 reflections, respectively, corresponding to gold silicide. In addition, the observed chemical shift of Au 4f and Si 2p lines in XPS spectrum of the irradiated surface illustrated the presence of gold silicide at the irradiated surface. The generation of Si/Au-Si alloy fibrous nanoparticles aggregate is explained by the nucleation and subsequent condensation of vapor in the plasma plume during irradiation and expulsion of molten material due to high plasma pressure.

  5. Gas turbine heat transfer and cooling technology

    CERN Document Server

    Han, Je-Chin; Ekkad, Srinath

    2012-01-01

    FundamentalsNeed for Turbine Blade CoolingTurbine-Cooling TechnologyTurbine Heat Transfer and Cooling IssuesStructure of the BookReview Articles and Book Chapters on Turbine Cooling and Heat TransferNew Information from 2000 to 2010ReferencesTurbine Heat TransferIntroductionTurbine-Stage Heat TransferCascade Vane Heat-Transfer ExperimentsCascade Blade Heat TransferAirfoil Endwall Heat TransferTurbine Rotor Blade Tip Heat TransferLeading-Edge Region Heat TransferFlat-Surface Heat TransferNew Information from 2000 to 20102.10 ClosureReferencesTurbine Film CoolingIntroductionFilm Cooling on Rotat

  6. Cooling systems

    International Nuclear Information System (INIS)

    Coutant, C.C.

    1978-01-01

    Progress on the thermal effects project is reported with regard to physiology and distribution of Corbicula; power plant effects studies on burrowing mayfly populations; comparative thermal responses of largemouth bass from northern and southern populations; temperature selection by striped bass in Cherokee Reservoir; fish population studies; and predictive thermoregulation by fishes. Progress is also reported on the following; cause and ecological ramifications of threadfin shad impingement; entrainment project; aquaculture project; pathogenic amoeba project; and cooling tower drift project

  7. Experimental and Numerical Investigation of the Effect of Process Conditions on Residual Wall Thickness and Cooling and Surface Characteristics of Water-Assisted Injection Molded Hollow Products

    Directory of Open Access Journals (Sweden)

    Hyungpil Park

    2015-01-01

    Full Text Available Recently, water-assisted injection molding was employed in the automobile industry to manufacture three-dimensional hollow tube-type products with functionalities. However, process optimization is difficult in the case of water-assisted injection molding because of the various rheological interactions between the injected water and the polymer. In this study, the boiling phenomenon that occurs because of the high melt temperature when injecting water and the molding characteristics of the hollow section during the water-assisted injection process were analyzed by a water-assisted injection molding analysis. In addition, the changes in the residual wall thickness accompanying changes in the process conditions were compared with the analysis results by considering water-assisted injection molding based on gas-assisted injection molding. Furthermore, by comparing the cooling characteristics and inner wall surface qualities corresponding to the formation of the hollow section by gas and water injections, a water-assisted injection molding technique was proposed for manufacturing hollow products with functionality.

  8. Size dependence of volume and surface nucleation rates for homogeneous freezing of supercooled water droplets

    Directory of Open Access Journals (Sweden)

    T. Kuhn

    2011-03-01

    Full Text Available The relative roles of volume and surface nucleation were investigated for the homogeneous freezing of pure water droplets. Experiments were carried out in a cryogenic laminar aerosol flow tube using supercooled water aerosols with maximum volume densities at radii between 1 and 3 μm. Temperature- and size-dependent values of volume- and surface-based homogeneous nucleation rates between 234.8 and 236.2 K were derived using a microphysical model and aerosol phase compositions and size distributions determined from infrared extinction measurements in the flow tube. The results show that the contribution from nucleation at the droplet surface increases with decreasing droplet radius and dominates over nucleation in the bulk droplet volume for droplets with radii smaller than approximately 5 μm. This is interpreted in terms of a lowered free energy of ice germ formation in the surface-based process. The implications of surface nucleation for the parameterization of homogeneous ice nucleation in numerical models are considered.

  9. Determining Cell-surface Expression and Endocytic Rate of Proteins in Primary Astrocyte Cultures Using Biotinylation.

    Science.gov (United States)

    Tham, Daniel Kai Long; Moukhles, Hakima

    2017-07-03

    Cell-surface proteins mediate a wide array of functions. In many cases, their activity is regulated by endocytic processes that modulate their levels at the plasma membrane. Here, we present detailed protocols for 2 methods that facilitate the study of such processes, both of which are based on the principle of the biotinylation of cell-surface proteins. The first is designed to allow for the semi-quantitative determination of the relative levels of a particular protein at the cell-surface. In it, the lysine residues of the plasma membrane proteins of cells are first labeled with a biotin moiety. Once the cells are lysed, these proteins may then be specifically precipitated via the use of agarose-immobilized streptavidin by exploiting the natural affinity of the latter for biotin. The proteins isolated in such a manner may then be analyzed via a standard western blotting approach. The second method provides a means of determining the endocytic rate of a particular cell-surface target over a period of time. Cell-surface proteins are first modified with a biotin derivative containing a cleavable disulfide bond. The cells are then shifted back to normal culture conditions, which causes the endocytic uptake of a proportion of biotinylated proteins. Next, the disulfide bonds of non-internalized biotin groups are reduced using the membrane-impermeable reducing agent glutathione. Via this approach, endocytosed proteins may thus be isolated and quantified with a high degree of specificity.

  10. Effect of Pad Surface Roughness on SiO2 Removal Rate in Chemical Mechanical Polishing with Ceria Slurry

    Science.gov (United States)

    Yoshida, Masato; Ono, Hiroshi; Nishiyama, Masaya; Ashizawa, Toranosuke; Doi, Toshiro

    2006-02-01

    The effect of pad surface roughness on SiO2 removal rate was investigated using four different slurries containing ceria (CeO2) powders of different crystallite sizes and mean particle sizes. A clear maximum was observed in the dependence of removal rate on pad surface roughness. The four ceria slurries showed a peak in blanket wafer removal rate against pad surface roughness Ra. The peak moved toward larger Ra values with decreasing ceria crystallite size. The removal rate was strongly influenced not only by pad surface roughness but also by the crystallite size of ceria in the slurry.

  11. Near-surface air temperature lapse rate in a humid mountainous terrain on the southern slopes of the eastern Himalayas

    Science.gov (United States)

    Kattel, Dambaru Ballab; Yao, Tandong; Panday, Prajjwal Kumar

    2018-05-01

    Based on climatic data from 18 stations on the southern slopes of the eastern Himalayas in Bhutan for the period from 1996 to 2009, this paper investigates monthly characteristics of the near-surface air temperature lapse rate (TLR). The station elevations used in this study range from 300 to 2760 m a. s. l. TLRs were evaluated using a linear regression model. The monthly values of maximum TLRs were always smaller than those of the minimum TLRs, which is in contrast to results from the surrounding mountainous regions. In this study, annual patterns of TLRs were somewhat consistent, particularly in the summer; during the other seasons, patterns contrasted to results from the southeastern Tibetan Plateau (China) and were almost comparable to results from Nepal. The shallowest observed values for TLRs in summer are due to intense latent heating at the higher elevation, associated with water vapor condensation from moist convection and evapotranspiration, and decreasing sensible heating at lower elevation, due to heavier rainfall, cloud, and forest cover. When compared to summer, the steeper TLRs in the non-monsoon season are due to sensible heating at the lower elevations, corresponding to dry and clear weather seasons, as well as increasing cooling at higher elevations, particularly in winter due to snow and cloud cover. Owing to lower albedo and higher aerodynamic roughness of forested areas, the TLRs were considerably reduced in daytime because of the dissipation of sensible heat to the atmospheric boundary layer. The distinct variation in diurnal TLR range is due to the diurnal variation in net radiation associated with reduced turbulent heating in the day and increased turbulent heating in the night, in addition to the effect of moisture and cloud cover. The shallower values of TLRs in this study when compared with the surrounding mountainous regions are due to high humidity, as well as the differing elevations and local climates.

  12. Simulation of an active cooling system for photovoltaic modules

    International Nuclear Information System (INIS)

    Abdelhakim, Lotfi

    2016-01-01

    Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

  13. Simulation of an active cooling system for photovoltaic modules

    Science.gov (United States)

    Abdelhakim, Lotfi

    2016-06-01

    Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

  14. Differences in rates of decrease of environmental radiation dose rates by ground surface property in Fukushima City after the Fukushima Daiichi nuclear power plant accident.

    Science.gov (United States)

    Kakamu, Takeyasu; Kanda, Hideyuki; Tsuji, Masayoshi; Kobayashi, Daisuke; Miyake, Masao; Hayakawa, Takehito; Katsuda, Shin-ichiro; Mori, Yayoi; Okouchi, Toshiyasu; Hazama, Akihiro; Fukushima, Tetsuhito

    2013-01-01

    After the Great East Japan Earthquake on 11 March 2011, the environmental radiation dose in Fukushima City increased. On 11 April, 1 mo after the earthquake, the environmental radiation dose rate at various surfaces in the same area differed greatly by surface property. Environmental radiation measurements continue in order to determine the estimated time to 50% reduction in environmental radiation dose rates by surface property in order to make suggestions for decontamination in Fukushima. The measurements were carried out from 11 April to 11 November 2011. Forty-eight (48) measurement points were selected, including four kinds of ground surface properties: grass (13), soil (5), artificial turf (7), and asphalt (23). Environmental radiation dose rate was measured at heights of 100 cm above the ground surface. Time to 50% reduction of environmental radiation dose rates was estimated for each ground surface property. Radiation dose rates on 11 November had decreased significantly compared with those on 11 April for all surface properties. Artificial turf showed the longest time to 50% reduction (544.32 d, standard error: 96.86), and soil showed the shortest (213.20 d, standard error: 35.88). The authors found the environmental radiation dose rate on artificial materials to have a longer 50% reduction time than that on natural materials. These results contribute to determining an order of priority for decontamination after nuclear disasters.

  15. Passive containment cooling water distribution device

    Science.gov (United States)

    Conway, Lawrence E.; Fanto, Susan V.

    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 a series of radial guide elements and cascading weir boxes to collect and then distribute the cooling water into a series of distribution areas through a plurality of cascading weirs. The cooling water is then uniformly distributed over the curved surface by a plurality of weir notches in the face plate of the weir box.

  16. Radon and Thoron Exhalation Rates from Surface Soil of Bangka - Belitung Islands, Indonesia

    Directory of Open Access Journals (Sweden)

    Syarbaini Syarbaini

    2015-03-01

    Full Text Available DOI:10.17014/ijog.2.1.35-42Radon and thoron exhalation rate from soil is one of the most important factors that can influence the radioactivity level in the environment. Radon and thoron gases are produced by the decay of the radioactive elements those are radium and thorium in the soil, where its concentration depends on the soil conditions and the local geological background. In this paper, the results of radon and thoron exhalation rate measurements from surface soil of Bangka Belitung Islands at thirty six measurement sites are presented. Exhalation rates of radon and thoron were measured by using an accumulation chamber equipped with a solid-state alpha particle detector. Furthermore, the correlations between radon and thoron exhalation rates with their parent nuclide (226Ra and 232Th concentrations in collected soil samples from the same locations were also evaluated. The result of the measurement shows that mostly the distribution of radon and thoron is similar to 226Ra and 232Th, eventhough it was not a good correlation between radon and thoron exhalation rate with their parent activity concentrations (226Ra and 232Th due to the environmental factors that can influence the radon and thoron mobilities in the soil. In comparison to a world average, Bangka Belitung Islands have the 222Rn and 220Rn exhalation rates higher than the world average value for the regions with normal background radiation.

  17. Near-surface air temperature lapse rates in Xinjiang, northwestern China

    Science.gov (United States)

    Du, Mingxia; Zhang, Mingjun; Wang, Shengjie; Zhu, Xiaofan; Che, Yanjun

    2018-02-01

    Lapse rates of near-surface (2 m) air temperature are important parameters in hydrologic and climate simulations, especially for the mountainous areas without enough in-situ observations. In Xinjiang, northwestern China, the elevations range from higher than 7000 m to lower than sea level, but the existing long-term meteorological measurements are limited and distributed unevenly. To calculate lapse rates in Xinjiang, the daily data of near-surface air temperature ( T min, T ave, and T max) were measured by automatic weather stations from 2012 to 2014. All the in situ observation stations were gridded into a network of 1.5° (latitude) by 1.5° (longitude), and the spatial distribution and the daily, monthly, seasonal variations of lapse rates for T min, T ave, and T max in Xinjiang are analyzed. The Urumqi River Basin has been considered as a case to study the influence of elevation, aspect, and the wet and dry air conditions to the T min, T ave, and T max lapse rates. Results show that (1) the lapse rates for T min, T ave, and T max vary spatially during the observation period. The spatial diversity of T min lapse rates is larger than that of T ave, and that of T max is the smallest. For each season, T max lapse rates have more negative values than T ave lapse rates which are steeper than T min lapse rates. The weakest spatial diversity usually appears in July throughout a year. (2) The comparison for the three subregions (North, Middle, and South region) exhibits that lapse rates have similar day-to-day and month-to-month characteristics which present shallower values in winter months and steeper values in summer months. The T ave lapse rates in North region are shallower than those in Middle and South region, and the steepest T ave lapse rates of the three regions all appear in April. T min lapse rates are shallower than T max lapse rates. The maximum medians of T min and T max lapse rates for each grid in the three regions all appear in January, whereas the

  18. X-Ray Burst Oscillations: From Flame Spreading to the Cooling Wake

    Science.gov (United States)

    Mahmoodifar, Simin; Strohmayer, Tod

    2016-01-01

    Type I X-ray bursts are thermonuclear flashes observed from the surfaces of accreting neutron stars (NSs) in low mass X-ray binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but large amplitude oscillations in the decay phase remain mysterious because of the absence of a clear-cut source of asymmetry. To date there have not been any quantitative studies that consistently track the oscillation amplitude both during the rise and decay (cooling tail) of bursts. Here we compute the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. We present results for several such "cooling wake" models, a "canonical" cooling model where each patch on the NS surface heats and cools identically, or with a latitude-dependent cooling timescale set by the local effective gravity, and an "asymmetric" model where parts of the star cool at significantly different rates. We show that while the canonical cooling models can generate oscillations in the tails of bursts, they cannot easily produce the highest observed modulation amplitudes. Alternatively, a simple phenomenological model with asymmetric cooling can achieve higher amplitudes consistent with the observations.

  19. Dosimetric perturbations of a lead shield for surface and interstitial high-dose-rate brachytherapy

    International Nuclear Information System (INIS)

    Candela-Juan, Cristian; Granero, Domingo; Vijande, Javier; Ballester, Facundo; Perez-Calatayud, Jose; Rivard, Mark J

    2014-01-01

    In surface and interstitial high-dose-rate brachytherapy with either 60 Co, 192 Ir, or 169 Yb sources, some radiosensitive organs near the surface may be exposed to high absorbed doses. This may be reduced by covering the implants with a lead shield on the body surface, which results in dosimetric perturbations. Monte Carlo simulations in Geant4 were performed for the three radionuclides placed at a single dwell position. Four different shield thicknesses (0, 3, 6, and 10 mm) and three different source depths (0, 5, and 10 mm) in water were considered, with the lead shield placed at the phantom surface. Backscatter dose enhancement and transmission data were obtained for the lead shields. Results were corrected to account for a realistic clinical case with multiple dwell positions. The range of the high backscatter dose enhancement in water is 3 mm for 60 Co and 1 mm for both 192 Ir and 169 Yb. Transmission data for 60 Co and 192 Ir are smaller than those reported by Papagiannis et al (2008 Med. Phys. 35 4898–4906) for brachytherapy facility shielding; for 169 Yb, the difference is negligible. In conclusion, the backscatter overdose produced by the lead shield can be avoided by just adding a few millimetres of bolus. Transmission data provided in this work as a function of lead thickness can be used to estimate healthy organ equivalent dose saving. Use of a lead shield is justified. (paper)

  20. Effects of surface cracks and strain rate on the tensile behavior of Balmoral Red granite

    Directory of Open Access Journals (Sweden)

    Mardoukhi Ahmad

    2015-01-01

    Full Text Available This paper presents an experimental procedure for studying the effects of surface cracks on the mechanical behavior of Balmoral Red granite under dynamic and quasi-static loading. Three different thermal shocks were applied on the surface of the Brazilian Disc test samples by keeping a flame torch at a fixed distance from the sample surface for 10, 30, and 60 seconds. Microscopy clearly shows that the number of the surface cracks increases with the duration of the thermal shock. After the thermal shock, the Brazilian Disc tests were performed using a servohydraulic materials testing machine and a compression Split Hopkinson Pressure Bar (SHPB device. The results show that the tensile strength of the rock decreases and the rate sensitivity of the rock increases as more cracks are introduced to the structure. The DIC analysis of the Brazilian disc tests shows that the fracture of the sample initiates at the center of the samples or slightly closer to the incident bar contact point. This is followed by crushing of the samples at both contact points with the stress bars.

  1. Escaping the correction for body surface area when calculating glomerular filtration rate in children

    Energy Technology Data Exchange (ETDEWEB)

    Piepsz, Amy; Tondeur, Marianne [CHU St. Pierre, Department of Radioisotopes, Brussels (Belgium); Ham, Hamphrey [University Hospital Ghent, Department of Nuclear Medicine, Ghent (Belgium)

    2008-09-15

    {sup 51}Cr ethylene diamine tetraacetic acid ({sup 51}Cr EDTA) clearance is nowadays considered as an accurate and reproducible method for measuring glomerular filtration rate (GFR) in children. Normal values in function of age, corrected for body surface area, have been recently updated. However, much criticism has been expressed about the validity of body surface area correction. The aim of the present paper was to present the normal GFR values, not corrected for body surface area, with the associated percentile curves. For that purpose, the same patients as in the previous paper were selected, namely those with no recent urinary tract infection, having a normal left to right {sup 99m}Tc MAG3 uptake ratio and a normal kidney morphology on the early parenchymal images. A single blood sample method was used for {sup 51}Cr EDTA clearance measurement. Clearance values, not corrected for body surface area, increased progressively up to the adolescence. The percentile curves were determined and allow, for a single patient, to estimate accurately the level of non-corrected clearance and the evolution with time, whatever the age. (orig.)

  2. Sympathetic Cooling of Quantum Simulators

    Science.gov (United States)

    Raghunandan, Meghana; Weimer, Hendrik

    2017-04-01

    We discuss the possibility of maximizing the cooling of a quantum simulator by controlling the system-environment coupling such that the system is driven into the ground state. We make use of various analytical tools such as effective operator formalism and the quantum master equations to exactly solve the model of an Ising spin chain consisting of N particles coupled to a radiation field. We maximize the cooling by finding the dependence of the effective rate of transitions of the various excited states into the ground state. We show that by adding a single dissipative qubit, we already get quite substantial cooling rates. Volkswagen Foundation, DFG.

  3. Evaluation Of Cooling Tower Degradation

    International Nuclear Information System (INIS)

    Djunaidi

    2001-01-01

    Cooling tower degradation has been evaluated for the last 10 years. Its heat transfer capacity has been decreasing after several years of operation due to aging. Evaluation is carried out by calculating the degradation rate, namely the annual increase of outlet temperatures of the cooling tower. Data was randomly taken daily at 15 MW reactor power. Data was taken after the reactor operation of ± 8 hours. Evaluation since 1990 shows that the degradation rate is nearly one degree per year. This degradation can be by minimized, replacement of damaged components, non-excessive operation and design modification of the cooling tower namely by extending the period of contract between water and air

  4. Rating

    OpenAIRE

    Karas, Vladimír

    2006-01-01

    Charakteristika ratingu. Dělení a druhy ratingu (rating emise × rating emitenta; dlouhodobý rating × krátkodobý rating; mezinárodní rating × lokální rating). Obecné požadavky kladené na rating. Proces tvorby ratingu. Vyžádaný rating. Nevyžádaný rating. Ratingový proces na bázi volně přístupných informací. Uplatňované ratingové systémy. Ratingová kriteria. Využití a interpretace ratingové známky. Funkce ratingu. Rating v souvislosti s BASEL II. Rating v souvislosti s hospodářskými krizemi....

  5. ATLAS - Liquid Cooling Systems

    CERN Multimedia

    Bonneau, P.

    1998-01-01

    Photo 1 - Cooling Unit - Side View Photo 2 - Cooling Unit - Detail Manifolds Photo 3 - Cooling Unit - Rear View Photo 4 - Cooling Unit - Detail Pump, Heater and Exchanger Photo 5 - Cooling Unit - Detail Pump and Fridge Photo 6 - Cooling Unit - Front View

  6. Collisional Dissociation of CO: ab initio Potential Energy Surfaces and Quasiclassical Trajectory Rate Coefficients

    Science.gov (United States)

    Schwenke, David W.; Jaffe, Richard L.; Chaban, Galina M.

    2016-01-01

    We have generated accurate global potential energy surfaces for CO+Ar and CO+O that correlate with atom-diatom pairs in their ground electronic states based on extensive ab initio electronic structure calculations and used these potentials in quasi-classical trajectory nuclear dynamics calculations to predict the thermal dissociation rate coefficients over 5000- 35000 K. Our results are not compatible with the 20-45 year old experimental results. For CO + Ar we obtain fairly good agreement with the experimental rate coefficients of Appleton et al. (1970) and Mick and Roth (1993), but our computed rate coefficients exhibit a stronger temperature dependence. For CO + O our dissociation rate coefficient is in close agreement with the value from the Park model, which is an empirical adjustment of older experimental results. However, we find the rate coefficient for CO + O is only 1.5 to 3.3 times larger than CO + Ar over the temperature range of the shock tube experiments (8000-15,000 K). The previously accepted value for this rate coefficient ratio is 15, independent of temperature. We also computed the rate coefficient for the CO + O ex- change reaction which forms C + O2. We find this reaction is much faster than previously believed and is the dominant process in the removal of CO at temperatures up to 16,000 K. As a result, the dissociation of CO is accomplished in two steps (react to form C+O2 and then O2 dissociates) that are endothermic by 6.1 and 5.1 eV, instead of one step that requires 11.2 eV to break the CO bond.

  7. Influence of Ultrasonic Melt Treatment and Cooling Rates on the Microstructural Development and Elevated Temperature Mechanical Properties of a Hypereutectic Al-18Si-4Cu-3Ni Piston Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jea-Hee; Cho, Young-Hee; Jung, Jae-Gil; Lee, Jung-Moo [Korea Institute of Materials Science (KIMS), Changwon (Korea, Republic of); Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2017-06-15

    The influence of ultrasonic melt treatment (UST) combined with a change in cooling rates on the microstructure and elevated temperature mechanical properties of a hypereutectic Al-18Si-4Cu-3Ni piston alloy was investigated. Microstructural observation confirmed that UST effectively refined the sizes of primary Si and intermetallic compounds (e.g. ε-Al{sub 3}Ni) while promoting their homogeneous distribution. Besides the refinement of the constituent phases, the size of the dendrite arm spacing (DAS), which was hardly affected by UST, significantly deceased with increasing cooling rates. The refinement of the solidification structure in the alloy achieved through both UST and increased cooling rates resulted in an improvement in tensile properties, ultimate tensile strength and elongation in particular, after T5 heat treatment followed by overaging at 350 ℃. However, the elevated temperature yield strength of the alloy was not associated with the refinement, but was rather correlated with the 3-D interconnectivity, morphology and volume fraction of the primary Si.

  8. Evaporation Rate of Distilled Water Drop on the Surface of Non-Ferrous Metals

    Directory of Open Access Journals (Sweden)

    Ponomarev Konstantin

    2015-01-01

    Full Text Available We studied experimentally the evaporation process of distilled water drops on the surfaces of non-ferrous metals. Investigations were conducted on the experimental setup using a shadow optical system. The main elements of this system are the source of plane-parallel light and photographic camera. According to the contact diameter change during the evaporation, three stages have been determined (spreading, pinning, depinning. It has been found, that the dependence of evaporation rate on drop volume at low temperatures appear to be well fit by a power function.

  9. Enhanced Sensitivity of Surface Acoustic Wave-Based Rate Sensors Incorporating Metallic Dot Arrays

    Directory of Open Access Journals (Sweden)

    Wen Wang

    2014-02-01

    Full Text Available A new surface acoustic wave (SAW-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz∙deg∙s−1 and good linearity were observed.

  10. Experimental study of the application of two trickle media for inlet air pre-cooling of natural draft dry cooling towers

    International Nuclear Information System (INIS)

    He, Suoying; Guan, Zhiqiang; Gurgenci, Hal; Hooman, Kamel; Lu, Yuanshen; Alkhedhair, Abdullah M.

    2015-01-01

    Highlights: • Two trickle media were experimentally studied in a low-speed wind tunnel. • Correlations for cooling efficiency and pressure drop were developed. • Both trickle media were proven to have relatively low pressure drops. • Both trickle media had severe water entrainment at large air velocities. - Abstract: This paper is part two of a broader investigation into pre-cooling the air that enters natural draft dry cooling towers. Evaporative cooling of air is to some extent different from evaporative cooling of water. Two trickle media (Trickle125 and Trickle100) originally designed for evaporative cooling of water were studied in an open-circuit wind tunnel for evaporative cooling of air. Three medium thicknesses (200, 300 and 450 mm) and two water flow rates (10 and 5 l/min per m 2 horizontally exposed surface area) were used in the tests. The air velocities ranged from 0.5 to 3.0 m/s. The cooling efficiency and the pressure drop of the two media were curve fitted to yield a set of correlations. The pressure drop ranges for Trickle125 and Trickle100 were 0.7–50 Pa and 0.6–41.6 Pa, respectively. The cooling efficiencies of Trickle125 and Trickle100 fell within 15.7–55.1% and 11–44.4%, respectively. Generally, media with large effective surfaces provide high cooling efficiencies and high pressure drops; there is a trade-off between cooling efficiency and pressure drop when selecting a particular medium for a specific application. The water entrainment off the media was detected with water-sensitive papers, and both media had severe water entrainment at large air velocities

  11. Seismic potential of weak, near-surface faults revealed at plate tectonic slip rates.

    Science.gov (United States)

    Ikari, Matt J; Kopf, Achim J

    2017-11-01

    The near-surface areas of major faults commonly contain weak, phyllosilicate minerals, which, based on laboratory friction measurements, are assumed to creep stably. However, it is now known that shallow faults can experience tens of meters of earthquake slip and also host slow and transient slip events. Laboratory experiments are generally performed at least two orders of magnitude faster than plate tectonic speeds, which are the natural driving conditions for major faults; the absence of experimental data for natural driving rates represents a critical knowledge gap. We use laboratory friction experiments on natural fault zone samples at driving rates of centimeters per year to demonstrate that there is abundant evidence of unstable slip behavior that was not previously predicted. Specifically, weak clay-rich fault samples generate slow slip events (SSEs) and have frictional properties favorable for earthquake rupture. Our work explains growing field observations of shallow SSE and surface-breaking earthquake slip, and predicts that such phenomena should be more widely expected.

  12. The surface quality of AWJ cut parts as a function of abrasive material reusing rate

    Science.gov (United States)

    Schnakovszky, C.; Herghelegiu, E.; Radu, M. C.; Tampu, N. C.

    2015-11-01

    Abrasive water jet cutting (AWJ) has been extensively used during the last years to process a large variety of materials since it offers important advantages as a good quality of the processed surface, without heat affected zones, low environmental impact (no emission of dust or other compounds that endanger the health of the user), small induced mechanical stresses etc. The main disadvantage is the high cost of processing (cost of equipment and consumables). In view of this, the effects of reusing the abrasive material on the quality of processed surface are investigated in this paper. Two steel materials were used: OL 37 (S 235) with large applicability in machine building industry and 2P armor steel used in the arms industry. The reusing rate of the garnet abrasive material was: 0%, 20%, 40%, 60%, 80% and 100%. The quality of processed surface was quantified by the following parameters: width at the jet inlet (Li), width at the jet outlet (Lo), inclination angle (α), deviation from perpendicularity (u) and roughness (Ra).

  13. A review of photovoltaic cells cooling techniques

    Science.gov (United States)

    Zubeer, Swar A.; Mohammed, H. A.; Ilkan, Mustafa

    2017-11-01

    This paper highlights different cooling techniques to reduce the operating temperature of the PV cells. This review paper focuses on the improvement of the performance of the small domestic use PV systems by keeping the temperature of the cells as low as possible and uniform. Different cooling techniques have been investigated experimentally and numerically the impact of the operating temperature of the cells on the electrical and thermal performance of the PV systems. The advantages and disadvantages of ribbed wall heat sink cooling, array air duct cooling installed beneath the PV panel, water spray cooling technique and back surface water cooling are examined in this paper to identify their effective impact on the PV panel performance. It was identified that the water spray cooling system has a proper impact on the PV panel performance. So the water cooling is one way to enhance the electrical efficiency of the PV panel.

  14. A review of photovoltaic cells cooling techniques

    Directory of Open Access Journals (Sweden)

    Zubeer Swar A.

    2017-01-01

    Full Text Available This paper highlights different cooling techniques to reduce the operating temperature of the PV cells. This review paper focuses on the improvement of the performance of the small domestic use PV systems by keeping the temperature of the cells as low as possible and uniform. Different cooling techniques have been investigated experimentally and numerically the impact of the operating temperature of the cells on the electrical and thermal performance of the PV systems. The advantages and disadvantages of ribbed wall heat sink cooling, array air duct cooling installed beneath the PV panel, water spray cooling technique and back surface water cooling are examined in this paper to identify their effective impact on the PV panel performance. It was identified that the water spray cooling system has a proper impact on the PV panel performance. So the water cooling is one way to enhance the electrical efficiency of the PV panel.

  15. General relativistic effects on the cooling of neutron stars

    International Nuclear Information System (INIS)

    Kindl, C.; Straumann, N.

    1981-01-01

    The authors present a discussion of general relativistic effects on the cooling of neutron stars and show analytically that these almost cancel for the dominant neutrino processes and a very stiff equation of state (apart from a trivial redshift of the surface temperature for an observer ''at infinity''). Numerical results for a ''realistic'' equation of state show larger general relativistic corrections. These are, however, still smaller than the uncertainties in the neutrino loss rates. Previous results of cooling curves would thus not be changed significantly by a general relativistic treatment of the thermal properties of neutron stars. (Auth.)

  16. Cool Snacks

    DEFF Research Database (Denmark)

    Krogager, Stinne Gunder Strøm; Grunert, Klaus G; Brunsø, Karen

    2016-01-01

    Young people snack and their snacking habits are not always healthy. We address the questions whether it is possible to develop a new snack product that adolescents will find attractive, even though it is based on ingredients as healthy as fruits and vegetables, and we argue that developing...... such a product requires an interdisciplinary effort where researchers with backgrounds in psychology, anthropology, media science, philosophy, sensory science and food science join forces. We present the COOL SNACKS project, where such a blend of competences was used first to obtain thorough insight into young...... people's snacking behaviour and then to develop and test new, healthier snacking solutions. These new snacking solutions were tested and found to be favourably accepted by young people. The paper therefore provides a proof of principle that the development of snacks that are both healthy and attractive...

  17. Cool visitors

    CERN Multimedia

    2006-01-01

    Pictured, from left to right: Tim Izo (saxophone, flute, guitar), Bobby Grant (tour manager), George Pajon (guitar). What do the LHC and a world-famous hip-hop group have in common? They are cool! On Saturday, 1st July, before their appearance at the Montreux Jazz Festival, three members of the 'Black Eyed Peas' came on a surprise visit to CERN, inspired by Dan Brown's Angels and Demons. At short notice, Connie Potter (Head of the ATLAS secretariat) organized a guided tour of ATLAS and the AD 'antimatter factory'. Still curious, lead vocalist Will.I.Am met CERN physicist Rolf Landua after the concert to ask many more questions on particles, CERN, and the origin of the Universe.

  18. Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

    Directory of Open Access Journals (Sweden)

    Xueping Du

    2018-04-01

    Full Text Available To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min.

  19. Is the surface oxygen exchange rate linked to bulk ion diffusivity in mixed conducting Ruddlesden-Popper phases?

    Science.gov (United States)

    Tomkiewicz, Alex C; Tamimi, Mazin A; Huq, Ashfia; McIntosh, Steven

    2015-01-01

    The possible link between oxygen surface exchange rate and bulk oxygen anion diffusivity in mixed ionic and electronic conducting oxides is a topic of great interest and debate. While a large body of experimental evidence and theoretical analyses support a link, observed differences between bulk and surface composition of these materials are hard to reconcile with this observation. This is further compounded by potential problems with simultaneous measurement of both parameters. Here we utilize separate techniques, in situ neutron diffraction and pulsed isotopic surface exchange, to examine bulk ion mobility and surface oxygen exchange rates of three Ruddlesden-Popper phases, general form A(n-1)A(2)'B(n)O(3n+1), A(n-1)A(2)'B(n)X(3n+1); LaSrCo(0.5)Fe(0.5)O(4-δ) (n = 1), La(0.3)Sr(2.7)CoFeO(7-δ) (n = 2) and LaSr3Co(1.5)Fe(1.5)O(10-δ) (n = 3). These measurements are complemented by surface composition determination via high sensitivity-low energy ion scattering. We observe a correlation between bulk ion mobility and surface exchange rate between materials. The surface exchange rates vary by more than one order of magnitude with high anion mobility in the bulk of an oxygen vacancy-rich n = 2 Ruddlesden-Popper material correlating with rapid oxygen exchange. This is in contrast with the similar surface exchange rates which we may expect due to similar surface compositions across all three samples. We conclude that experimental limitations lead to inherent convolution of surface and bulk rates, and that surface exchange steps are not likely to be rate limiting in oxygen incorporation.

  20. Improvement of thermal comfort by cooling clothing in warm climate

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Melikov, Arsen Krikor; Kolencíková, Sona

    2014-01-01

    on the inner surface. We conducted experiments with human subjects in climate chambers maintained at 30 °C and RH 50% to compare the effectiveness of the cooling clothing with that of other convective cooling devices. The use of cooling clothing with a convective cooling device improved the subjects’ thermal...

  1. Effect of Deposition Rate on Structure and Surface Morphology of Thin Evaporated Al Films on Dielectrics and Semiconductors

    DEFF Research Database (Denmark)

    Bordo, K.; Rubahn, H. G.

    2012-01-01

    . The structure and surface morphology of the as-deposited Al films were studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM imaging of the films showed that the mean grain size of thin Al films on all of the substrates increased from 20 nm - 30 nm to 50 nm - 70 nm...... with increase of the deposition rate. Quantitative AFM characterization showed that for all substrates the root mean square surface roughness increases monotonically with increasing the deposition rate from 0.1 nm/s to 2 nm/s. The observed effects of the deposition rate on the grain size and surface roughness...

  2. Dry period cooling ameliorates physiological variables and blood acid base balance, improving milk production in murrah buffaloes

    Science.gov (United States)

    Aarif, Ovais; Aggarwal, Anjali

    2016-03-01

    This study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subsequent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly ( P < 0.05) lower in group 2, with the provision of cooling. Skin surface temperature at thorax was significantly lower in cooled group relative to noncooled group. Blood pH and pO2 were significantly ( P < 0.05) higher in heat stressed group as compared to the cooled group. pCO2, TCO2, HCO3, SBC, base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly ( P < 0.05) higher in cooled group as compared to noncooled group. DMI was significantly ( P < 0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher ( P < 0.05) in cooled group of Murrah buffaloes.

  3. Response surface modelling of tool electrode wear rate and material removal rate in micro electrical discharge machining of Inconel 718

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2017-01-01

    conductivity and high strength causing it extremely difficult tomachine. Micro-Electrical Discharge Machining (Micro-EDM) is a non-conventional method that has a potential toovercome these restrictions for machining of Inconel 718. Response Surface Method (RSM) was used for modelling thetool Electrode Wear...

  4. In situ cosmogenic 53Mn production rate from ancient low-denudation surface in tropic Brazil

    International Nuclear Information System (INIS)

    Fujioka, T.; Fifield, L.K.; Stone, J.O.; Vasconcelos, P.M.; Tims, S.G.; Chappell, J.

    2010-01-01

    Preliminary results of 53 Mn measurements for seven Brazilian haematites are presented. The production rate of 53 Mn due to cosmic-ray induced disintegration of iron is estimated to be 103 ± 19 atoms g(Fe) -1 yr -1 at sea level and high latitude. This is consistent with the only previously published measurement. The muon contribution to the total 53 Mn production at the surface is estimated to be ∼7%. Cosmogenic-isotope dating employing 53 Mn is applicable to any rock/mineral type that contains iron as a major constituent, such as haematite, goethite, pyroxene and olivine. The method has the potential to extend the time scale of cosmogenic exposure dating to >10 Ma.

  5. WORKSHOP: Beam cooling

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    Cooling - the control of unruly particles to provide well-behaved beams - has become a major new tool in accelerator physics. The main approaches of electron cooling pioneered by Gersh Budker at Novosibirsk and stochastic cooling by Simon van der Meer at CERN, are now complemented by additional ideas, such as laser cooling of ions and ionization cooling of muons

  6. Is thermospheric long-term cooling due to CO2 or O3?

    Directory of Open Access Journals (Sweden)

    P. L. Walsh

    2011-10-01

    Full Text Available While greenhouse gases trap heat emanating from the Earth and thereby heat the surface atmosphere, they act as emitters in the high atmosphere and cool the air there. In 1989 Roble and Dickinson (1989 estimated the cooling that would occur in the thermosphere (250–500 km altitude due to a doubling of greenhouse gas densities. Ever since, long-term data bases have been scoured for evidence of this thermospheric "global cooling." Here we show evidence that the thermosphere did indeed cool over the period 1966–1987, but the data suggest that the cooling accelerated at a "breakpoint year" around 1979 to a rate far larger than may be attributed to greenhouse cooling. This 1979 breakpoint year appears to coincide with a breakpoint year in ozone (O3 column density. Further, the cooling was confined largely to the daytime thermosphere while the nighttime showed only a small trend. These results suggest, first, that the greenhouse cooling of the thermosphere may well not be detectable with current data sets and, second, that the long-term cooling that is clearly seen may be due largely to O3 depletion.

  7. The Advancement of Cool Roof Standards in China from 2010 to 2015

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Jing [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Levinson, Ronnen M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-11-01

    Since the initiation of the U.S.-China Clean Energy Research Center-Building Energy Efficiency (CERC-BEE) cool roof research collaboration between the Lawrence Berkeley National Laboratory Heat Island Group and Chinese institutions in 2010, new cool surface credits (insulation trade- offs) have been adopted in Chinese building energy efficiency standards, industry standards, and green building standards. JGJ 75-2012: Design Standard for Energy Efficiency of Residential Buildings in Hot Summer and Warm Winter Zone became the first national level standard to provide cool surface credits. GB/T 50378-2014: Assessment Standard for Green Building is the first national level green building standard that offers points for heat island mitigation. JGJ/T 359-2015: Technical Specification for Application of Architectural Reflective Thermal Insulation Coating is the first industry standard that offers cool coating credits for both public and residential buildings in all hot-summer climates (Hot Summer/Cold Winter, Hot Summer/Warm Winter). As of December 2015, eight provinces or municipalities in hot-summer regions have credited cool surfaces credits in their residential and/or public building design standards; five other provinces or municipalities in hot-summer regions recommend, but do not credit, the use of cool surfaces in their building design standards. Cool surfaces could be further advanced in China by including cool roof credits for residential and public building energy efficiency standards in all hot-summer regions; developing a standardized process for natural exposure and aged-property rating of cool roofing products; and adapting the U.S.-developed laboratory aging process for roofing materials to replicate solar reflectance changes induced by natural exposure in China.

  8. Interactions between Cool Roofs and Urban Irrigation: Do Cooling Strategies Reduce Water Consumption in the San Francisco Bay Area?

    Science.gov (United States)

    Vahmani, P.; Jones, A. D.

    2016-12-01

    California has experienced progressive drought since 2012, with 2012-2014 constituting a nearly 10,000-year drought event, resulting in a suite of policies with the goal of reducing water consumption. At the same time, climate warming effects of accelerated urbanization along with projected global climate change raise an urgent need for sustainable mitigation and adaptation strategies to cool urban climates. In this study, for the first time, we assess the overarching benefits of cooling strategies on urban water consumption. We employ a satellite-supported regional climate-modeling framework over the San Francisco Bay Area to assess the effects of cool roofs on urban irrigation, a topic of increasing importance as it accounts for a significant fraction of urban water use particularly in arid and semi-arid regions. We use a suit of climatological simulations at high (1.5 km) spatial resolution, based on a Weather Research and Forecasting (WRF)-Urban Canopy Model (UCM) modeling framework, reinforced with remotely sensed observations of Green Vegetation Fraction (GVF), leaf area index (LAI), and albedo. Our analysis shows that widespread incorporation of cool roofs would result in a mean daytime cooling of about 0.7° C, which in turn results in roughly 4% reduction in irrigation water, largely due to decreases in surface evapotranspiration rates. We further investigate the critical interactions between cool roofs, wind, and sea-breeze patterns as well as fog formation, a dominant weather pattern in San Francisco Bay area.

  9. Optimum dry-cooling sub-systems for a solar air conditioner

    Science.gov (United States)

    Chen, J. L. S.; Namkoong, D.

    1978-01-01

    Dry-cooling sub-systems for residential solar powered Rankine compression air conditioners were economically optimized and compared with the cost of a wet cooling tower. Results in terms of yearly incremental busbar cost due to the use of dry-cooling were presented for Philadelphia and Miami. With input data corresponding to local weather, energy rate and capital costs, condenser surface designs and performance, the computerized optimization program yields design specifications of the sub-system which has the lowest annual incremental cost.

  10. Airfoil, platform, and cooling passage measurements on a rotating transonic high-pressure turbine

    Science.gov (United States)

    Nickol, Jeremy B.

    compressibility effects within the cooling holes which are not present in low speed experiments. Another major focus of this work is on the forward purge cavity and rotor and stator inner endwalls. Pressure and heat transfer measurements are taken at several locations, and compared as both forward and aft purge flow rates are varied. It is seen that increases in forward purge rates result in a flow blockage and greater pressure on the endwalls both up and downstream of the cavity. Thus, even in locations where the coolant does not directly cover the metal surface, it can have a significant impact on the local pressure loading and heat transfer rate. The heat transfer on the platform further downstream, however, is unchanged by variations in purge flow rates.

  11. Effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhi [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Department of Bone and Joint Surgery, The affiliated hospital of Luzhou Medical College, Luzhou 646000 (China); Qing, Quan [Sichuan College of Traditional Chinese Medicine, Mianyang 621000 (China); Regenerative Medicine Research Center, West China Hospital of Sichuan University, Chengdu 610041 (China); Chen, Xi; Liu, Cheng-Jun; Luo, Jing-Cong [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Hu, Jin-Lian [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Qin, Ting-Wu, E-mail: tingwuqin@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China)

    2016-12-01

    Highlights: • The shapes of tenocytes varied when seeded on different surface of scaffolds. • Tenocytes were flat on smooth surface and spindle on micro-grooved surface. • Tenocytes were ellipse or spindle on porous surface. • Tenocytes got varying adhesion shape and elongation index on varying surfaces. • The tenocyte survival on porous surface was superior to the other two groups. - Abstract: The purpose of this study was to investigate the effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs. Tenocytes were obtained from tail tendons of rats. Polydimethylsiloxane (PDMS) was used to fabricate three types of scaffolds with varying surface morphological characteristics, i.e., smooth, micro-grooved, and porous surfaces, respectively. The tenocytes were seeded on the surfaces of the scaffolds to form tenocyte-scaffold constructs. The constructs were cryopreserved in a vitreous cryoprotectant (CPA) with a multi-step protocol. The cell adhesion to scaffolds was observed with electronic scanning microscopy (SEM). The elongation index of the living tenocytes and ratio of live/dead cell number were examined based on a live/dead dual fluorescent staining technique, and the survival rate of tenocytes was studied with flow cytometry (FC). The results showed the shapes of tenocytes varied between the different groups: flat or polygonal (on smooth surface), spindle (on micro-grooved surface), and spindle or ellipse (on porous surface). After thawing, the porous surface got the most living tenocytes and a higher survival rate, suggesting its potential application for vitreous cryopreservation of engineered tendon constructs.

  12. The effect of cooling rate on the phase formation and magnetocaloric properties in La0.6Ce0.4Fe11.0Si2.0 alloys

    Science.gov (United States)

    Yang, Jian; Shao, Yanyan; Feng, Zaixin; Liu, Jian

    2018-04-01

    In this work, the microstructure, phase formation behavior of the NaZn13-type 1:13 phase and related magnetocaloric effect have been investigated in La0.6Ce0.4Fe11.0Si2.0 as-cast bulk and melt-spun ribbons with different cooling rates. A multi-phase structure consisting of 1:13, α-Fe and La-rich phases is observed in the induction-melted sample with slow cooling. By fast cooling in the melt spinning processing, the La-rich phase can be almost eliminated and thus 1:13 phases with volume fraction as high as 74.4% directly form in the absence of further heat treatment. The resulting maximum magnetic entropy change of 3.1 J/kg K in 2 T field appears at its Curie temperature of 210 K for the La0.6Ce0.4Fe11.0Si2.0 ribbon prepared in 25 m/s.

  13. Influence of external cooling on the femtosecond laser ablation of dentin.

    Science.gov (United States)

    Le, Q T; Vilar, R; Bertrand, C

    2017-12-01

    In the present work, the influence of external cooling on the temperature rise in the tooth pulpal chamber during femtosecond laser ablation was investigated. The influence of the cooling method on the morphology and constitution of the laser-treated surfaces was studied as well. The ablation experiments were performed on dentin specimens using an Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs, 1030 nm). Cavities were created by scanning the specimens at a velocity of 5 mm/s while pulsing the stationary laser beam at 1 kHz and with fluences in the range of 2-14 J/cm 2 . The experiments were performed in air and with surface cooling by a lateral air jet and by a combination of an air jet and water irrigation. The temperature in the pulpal chamber of the tooth was measured during the laser experiments. The ablation surfaces were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The temperature rise reached 17.5 °C for the treatments performed with 14 J/cm 2 and without cooling, which was reduced to 10.8 ± 1.0 and 6.6 ± 2.3 °C with forced air cooling and water cooling, respectively, without significant reduction of the ablation rate. The ablation surfaces were covered by ablation debris and resolidified droplets containing mainly amorphous calcium phosphate, but the amount of redeposited debris was much lower for the water-cooled specimens. The redeposited debris could be removed by ultrasonication, revealing that the structure and constitution of the tissue remained essentially unaltered. The present results show that water cooling is mandatory for the femtosecond laser treatment of dentin, in particular, when high fluences and high pulse repetition rates are used to achieve high material removal rates.

  14. Improving of the photovoltaic / thermal system performance using water cooling technique

    International Nuclear Information System (INIS)

    Hussien, Hashim A; Numan, Ali H; Abdulmunem, Abdulmunem R

    2015-01-01

    This work is devoted to improving the electrical efficiency by reducing the rate of thermal energy of a photovoltaic/thermal system (PV/T).This is achieved by design cooling technique which consists of a heat exchanger and water circulating pipes placed at PV module rear surface to solve the problem of the high heat stored inside the PV cells during the operation. An experimental rig is designed to investigate and evaluate PV module performance with the proposed cooling technique. This cooling technique is the first work in Iraq to dissipate the heat from PV module. The experimental results indicated that due to the heat loss by convection between water and the PV panel's upper surface, an increase of output power is achieved. It was found that without active cooling, the temperature of the PV module was high and solar cells could only achieve a conversion efficiency of about 8%. However, when the PV module was operated under active water cooling condition, the temperature was dropped from 76.8°C without cooling to 70.1°C with active cooling. This temperature dropping led to increase in the electrical efficiency of solar panel to 9.8% at optimum mass flow rate (0.2L/s) and thermal efficiency to (12.3%). (paper)

  15. Emergent relation between surface vapor conductance and relative humidity profiles yields evaporation rates from weather data.

    Science.gov (United States)

    Salvucci, Guido D; Gentine, Pierre

    2013-04-16

    The ability to predict terrestrial evapotranspiration (E) is limited by the complexity of rate-limiting pathways as water moves through the soil, vegetation (roots, xylem, stomata), canopy air space, and the atmospheric boundary layer. The impossibility of specifying the numerous parameters required to model this process in full spatial detail has necessitated spatially upscaled models that depend on effective parameters such as the surface vapor conductance (C(surf)). C(surf) accounts for the biophysical and hydrological effects on diffusion through the soil and vegetation substrate. This approach, however, requires either site-specific calibration of C(surf) to measured E, or further parameterization based on metrics such as leaf area, senescence state, stomatal conductance, soil texture, soil moisture, and water table depth. Here, we show that this key, rate-limiting, parameter can be estimated from an emergent relationship between the diurnal cycle of the relative humidity profile and E. The relation is that the vertical variance of the relative humidity profile is less than would occur for increased or decreased evaporation rates, suggesting that land-atmosphere feedback processes minimize this variance. It is found to hold over a wide range of climate conditions (arid-humid) and limiting factors (soil moisture, leaf area, energy). With this relation, estimates of E and C(surf) can be obtained globally from widely available meteorological measurements, many of which have been archived since the early 1900s. In conjunction with precipitation and stream flow, long-term E estimates provide insights and empirical constraints on projected accelerations of the hydrologic cycle.

  16. Renewable Heating And Cooling

    Science.gov (United States)

    Renewable heating and cooling is a set of alternative resources and technologies that can be used in place of conventional heating and cooling technologies for common applications such as water heating, space heating, space cooling and process heat.

  17. The microstructure and magnetic properties of Nd8.5Tb1.5Fe83Zr1B6 ribbons obtained at various cooling rates

    Directory of Open Access Journals (Sweden)

    Dośpiał Marcin

    2015-03-01

    Full Text Available The paper presents results of microstructure and magnetic properties studies of Nd8.5Tb1.5Fe83Zr1B6 ribbons obtained by melt-spinning technique. The samples were produced using the rapid cooling of liquid alloy on the copper wheel, by applying three different linear velocities 20, 30, and 35 m/s. The microstructure of obtained ribbons was examined using X-ray diffractometry and Mössbauer spectroscopy. Magnetic measurements were performed using LakeShore vibrating sample magnetometer. The microstructure measurements were used for quantitative and qualitative analysis of phase composition. Basing on results of structure studies combined with magnetic measurements, the influence of phase composition on hysteresis loop behavior was described.

  18. Modeling dose-rate on/over the surface of cylindrical radio-models using Monte Carlo methods

    International Nuclear Information System (INIS)

    Xiao Xuefu; Ma Guoxue; Wen Fuping; Wang Zhongqi; Wang Chaohui; Zhang Jiyun; Huang Qingbo; Zhang Jiaqiu; Wang Xinxing; Wang Jun

    2004-01-01

    Objective: To determine the dose-rates on/over the surface of 10 cylindrical radio-models, which belong to the Metrology Station of Radio-Geological Survey of CNNC. Methods: The dose-rates on/over the surface of 10 cylindrical radio-models were modeled using the famous Monte Carlo code-MCNP. The dose-rates on/over the surface of 10 cylindrical radio-models were measured by a high gas pressurized ionization chamber dose-rate meter, respectively. The values of dose-rate modeled using MCNP code were compared with those obtained by authors in the present experimental measurement, and with those obtained by other workers previously. Some factors causing the discrepancy between the data obtained by authors using MCNP code and the data obtained using other methods are discussed in this paper. Results: The data of dose-rates on/over the surface of 10 cylindrical radio-models, obtained using MCNP code, were in good agreement with those obtained by other workers using the theoretical method. They were within the discrepancy of ±5% in general, and the maximum discrepancy was less than 10%. Conclusions: As if each factor needed for the Monte Carlo code is correct, the dose-rates on/over the surface of cylindrical radio-models modeled using the Monte Carlo code are correct with an uncertainty of 3%

  19. In-situ GPS records of surface mass balance, firn compaction rates, and ice-shelf basal melt rates for Pine Island Glacier, Antarctica

    Science.gov (United States)

    Shean, D. E.; Christianson, K.; Larson, K. M.; Ligtenberg, S.; Joughin, I. R.; Smith, B.; Stevens, C.

    2016-12-01

    In recent decades, Pine Island Glacier (PIG) has experienced marked retreat, speedup and thinning due to ice-shelf basal melt, internal ice-stream instability and feedbacks between these processes. In an effort to constrain recent ice-stream dynamics and evaluate potential causes of retreat, we analyzed 2008-2010 and 2012-2014 GPS records for PIG. We computed time series of horizontal velocity, strain rate, multipath-based antenna height, surface elevation, and Lagrangian elevation change (Dh/Dt). These data provide validation for complementary high-resolution WorldView stereo digital elevation model (DEM) records, with sampled DEM vertical error of 0.7 m. The GPS antenna height time series document a relative surface elevation increase of 0.7-1.0 m/yr, which is consistent with estimated surface mass balance (SMB) of 0.7-0.9 m.w.e./yr from RACMO2.3 and firn compaction rates from the IMAU-FDM dynamic firn model. An abrupt 0.2-0.3 m surface elevation decrease due to surface melt and/or greater near-surface firn compaction is observed during a period of warm atmospheric temperatures from December 2012 to January 2013. Observed surface Dh/Dt for all PIG shelf sites is highly linear with trends of -1 to -4 m/yr and PIG shelf and 4 m/yr for the South shelf. These melt rates are similar to those derived from ice-bottom acoustic ranging, phase-sensitive ice-penetrating radar, and high-resolution stereo DEM records. The GPS/DEM records document higher melt rates within and near transverse surface depressions and rifts associated with longitudinal extension. Basal melt rates for the 2012-2014 period show limited temporal variability, despite significant change in ocean heat content. This suggests that sub-shelf melt rates are less sensitive to ocean heat content than previously reported, at least for these locations and time periods.

  20. Restaurant food cooling practices.

    Science.gov (United States)

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

    2012-12-01

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

  1. Effects of Micro-fin Structure on Spray Cooling Heat Transfer in Forced Convection and Nucleate Boiling Region

    International Nuclear Information System (INIS)

    Kim, Yeung Chan

    2010-01-01

    In the present study, spray cooling heat transfer was experimentally investigated for the case in which water is sprayed onto the surfaces of micro-fins in forced convection and nucleate boiling regions. The experimental results show that an increase in the droplet flow rate improves heat transfer due to forced convection and nucleate boiling in the both case of smooth surface and surfaces of micro-fins. However, the effect of subcooling for fixed droplet flow rate is very weak. Micro-fins surfaces enhance the spray cooling heat transfer significantly. In the dilute spray region, the micro-fin structure has a significant effect on the spray cooling heat transfer. However, this effect is weak in the dense spray region. A previously determined correlation between the Nusselt number and Reynolds number shows good agreement with the present experimental data for a smooth surface

  2. Cooling device for upper lid of reactor pressure vessel

    International Nuclear Information System (INIS)

    Takayama, Kazuhiko.

    1997-01-01

    An upper lid of a reactor pressure vessel in a BWR type reactor has one or more annular cooling elements on the surface. The outer side thereof is covered by a temperature keeping frame. The cooling elements have an annular hollow shape, and cooling water is supplied to the hollow portion. As the cooling water supplied to the cooling elements, cooling water of a reactor auxiliary cooling system as a cooling water system incorporated in the reactor container or cooling water of a dehumidification system of the reactor container is used. A plurality of temperature sensors are disposed to various portions of the upper lid of the pressure vessel. A control device determines scattering of the temperature for the entire upper lid of the pressure vessel by temperature signals sent from the temperature sensors. Then, the amount of cooling water to be flown to each of the cooling elements is controlled so as to eliminate the scattering. (I.N.)

  3. Impact of source position on high-dose-rate skin surface applicator dosimetry.

    Science.gov (United States)

    Jeong, Jeho; Barker, Christopher A; Zaider, Marco; Cohen, Gil'ad N

    2016-01-01

    Skin surface dosimetric discrepancies between measured and treatment planning system predicted values were traced to source position sag inside the applicator and to source transit time. We quantified their dosimetric impact and propose corrections for clinical use. We measured the dose profiles from the Varian Leipzig-style high-dose-rate (HDR) skin applicator, using EBT3 film, photon diode, and optically stimulated luminescence dosimeter for three different GammaMedplus HDR afterloaders. The measured dose profiles at several depths were compared with BrachyVision Acuros calculated profiles. To assess the impact of the source sag, two different applicator orientations were considered. The dose contribution during source transit was assessed by comparing diode measurements using an HDR timer and an electrometer timer. Depth doses measured using the three dosimeters were in good agreement, but were consistently higher than the Acuros dose calculations. Measurements with the applicator face up were significantly (exceeding 10%) lower than those in the face down position, due to source sag inside the applicator. Based on the inverse square law, the effective source sag was evaluated to be about 0.5 mm from the planned position. The additional dose during source transit was evaluated to be about 2.8% for 30 seconds of treatment with a 40700 U (10 Ci) source. With a very short source-to-surface distance, the small source sag inside the applicator has a significant dosimetric impact. This effect is unaccounted for in the vendor's treatment planning template and should be considered before the clinical use of the applicator. Further investigation of other applicators with large source lumen diameter may be warranted. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  4. [Therapeutic hypothermia after cardiac arrest. A cold intravenous fluid, a cooling helmet and a cooling blanket efficiently reduce body temperature].

    Science.gov (United States)

    Friberg, Hans; Nielsen, Niklas; Karlsson, Torbjörn; Cronberg, Tobias; Widner, Håkan; Englund, Elisabet; Ersson, Anders

    2004-07-22

    Two controlled randomized trials have shown that mild systemic hypothermia after cardiac arrest is beneficial for neurological outcome and one of the studies shows an improved survival rate. A pilot study was performed to evaluate a model of induced hypothermia after cardiac arrest, using cold intravenous fluids and surface cooling with a cold helmet and a coldwater blanket (Thermowrap). The main purpose was to evaluate our cooling method regarding efficacy, safety and usability. Five unconscious patients after cardiac arrest were treated with induced hypothermia of whom three survived with good recovery to six-month follow up. Two patients died in the ICU without regaining consciousness. There were no adverse events during treatment. We conclude that our method is reasonably fast compared to other published methods, it is easy to perform and it offers a good temperature control during cooling and rewarming. Routines for evaluating prognosis and neurological outcome after cardiac arrest and hypothermia treatment need to be revised.

  5. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    Science.gov (United States)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  6. Heart rate variability and surface electromyography of trained cyclists at different cadences

    Directory of Open Access Journals (Sweden)

    Bruno Saraiva

    2016-06-01

    Full Text Available The heart rate variability (HRV and surface electromyography (sEMG are important tools in the evaluation of cardiac autonomic system and neuromuscular parameters, respectively. The aim of the study was to evaluate the behavior of HRV and sEMG of the vastus lateralis in two exercise protocols on a cycle ergometer at 60 and 80 rpm. Eight healthy men cyclists who have trained for at least two years were evaluated. Reduction was observed followed by stabilization of RMSSD and SDNN indices of HRV (p<0.05 along with increases in the amplitude of the sEMG signal (p<0.05 in both protocols. Significant correlations were observed between the responses of HRV and sEMG in the cadence of 60 rpm (RMSSD and sEMG: r = -0.42, p=0.03; SDNN and sEMG: r = -0.45, p=0.01 and 80 rpm (RMSSD and sEMG: r = -0.47, p=0.02; SDNN and sEMG: r = -0.49, p=0.01, yet no difference was observed for these variables between the two protocols. We concluded that the parasympathetic cardiac responses and sEMG are independent of cadences applied at the same power output.

  7. A Krebs Cycle Component Limits Caspase Activation Rate through Mitochondrial Surface Restriction of CRL Activation.

    Science.gov (United States)

    Aram, Lior; Braun, Tslil; Braverman, Carmel; Kaplan, Yosef; Ravid, Liat; Levin-Zaidman, Smadar; Arama, Eli

    2016-04-04

    How cells avoid excessive caspase activity and unwanted cell death during apoptotic caspase-mediated removal of large cellular structures is poorly understood. We investigate caspase-mediated extrusion of spermatid cytoplasmic contents in Drosophila during spermatid individualization. We show that a Krebs cycle component, the ATP-specific form of the succinyl-CoA synthetase β subunit (A-Sβ), binds to and activates the Cullin-3-based ubiquitin ligase (CRL3) complex required for caspase activation in spermatids. In vitro and in vivo evidence suggests that this interaction occurs on the mitochondrial surface, thereby limiting the source of CRL3 complex activation to the vicinity of this organelle and reducing the potential rate of caspase activation by at least 60%. Domain swapping between A-Sβ and the GTP-specific SCSβ (G-Sβ), which functions redundantly in the Krebs cycle, show that the metabolic and structural roles of A-Sβ in spermatids can be uncoupled, highlighting a moonlighting function of this Krebs cycle component in CRL activation. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Survey of materials and corrosion performance in dry cooling applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.B.; Pratt, D.R.; Zima, G.E.

    1976-03-01

    The report presented summarizes aqueous and air-side corrosion aspects of candidate materials in dry cooling applications. The applications include piping, condensers, louvers, structures, and the air-cooled surfaces.

  9. Tear-Film Evaporation Rate from Simultaneous Ocular-Surface Temperature and Tear-Breakup Area.

    Science.gov (United States)

    Dursch, Thomas J; Li, Wing; Taraz, Baseem; Lin, Meng C; Radke, Clayton J

    2018-01-01

    A corneal heat-transfer model is presented to quantify simultaneous measurements of fluorescein tear-breakup area (TBA) and ocular-surface temperature (OST). By accounting for disruption of the tear-film lipid layer (TFLL), we report evaporation rates through lipid-covered tear. The modified heat-transfer model provides new insights into evaporative dry eye. A quantitative analysis is presented to assess human aqueous tear evaporation rate (TER) through intact TFLLs from simultaneous in vivo measurement of time-dependent infrared OST and fluorescein TBA. We interpret simultaneous OST and TBA measurements using an extended heat-transfer model. We hypothesize that TBAs are ineffectively insulated by the TFLL and therefore exhibit higher TER than does that for a well-insulting TFLL-covered tear. As time proceeds, TBAs increase in number and size, thereby increasing the cornea area-averaged TER and decreasing OST. Tear-breakup areas were assessed from image analysis of fluorescein tear-film-breakup video recordings and are included in the heat-transfer description of OST. Model-predicted OSTs agree well with clinical experiments. Percent reductions in TER of lipid-covered tear range from 50 to 95% of that for pure water, in good agreement with literature. The physical picture of noninsulating or ruptured TFLL spots followed by enhanced evaporation from underlying cooler tear-film ruptures is consistent with the evaporative-driven mechanism for local tear rupture. A quantitative analysis is presented of in vivo TER from simultaneous clinical measurement of transient OST and TBA. The new heat-transfer model accounts for increased TER through expanding TBAs. Tear evaporation rate varies strongly across the cornea because lipid is effectively missing over tear-rupture troughs. The result is local faster evaporation compared with nonruptured, thick lipid-covered tear. Evaporative-driven tear-film ruptures deepen to a thickness where fluorescein quenching commences and local

  10. Power electronics substrate for direct substrate cooling

    Science.gov (United States)

    Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

    2012-05-01

    Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

  11. Compositional variations for small-scale gamma prime (γ′) precipitates formed at different cooling rates in an advanced Ni-based superalloy

    International Nuclear Information System (INIS)

    Chen, Y.Q.; Francis, E.; Robson, J.; Preuss, M.; Haigh, S.J.

    2015-01-01

    Size-dependent compositional variations under different cooling regimes have been investigated for ordered L1 2 -structured gamma prime (γ′) precipitates in the commercial powder metallurgy Ni-based superalloy RR1000. Using scanning transmission electron microscope imaging combined with absorption-corrected energy-dispersive X-ray spectroscopy, we have discovered large differences in the Al, Ti and Co compositions for γ′ precipitates in the size range 10–300 nm. Our experimental results, coupled with complementary thermodynamic calculations, demonstrate the importance of kinetic factors on precipitate composition in Ni-based superalloys. In particular, these results provide new evidence for the role of elemental diffusion kinetics and aluminium antisite atoms on the low-temperature growth kinetics of fine-scale γ′ precipitates. Our findings have important implications for understanding the microstructure and precipitation behaviour of Ni-based superalloys, suggesting a transition in the mechanism of vacancy-mediated diffusion of Al from intrasublattice exchange at high temperatures to intersublattice antisite-assisted exchange at low temperatures

  12. Variable-focus microscopy and UV surface dissolution imaging as complementary techniques in intrinsic dissolution rate determination

    DEFF Research Database (Denmark)

    Ward, Adam; Walton, Karl; Box, Karl

    2017-01-01

    This work reports a novel approach to the assessment of the surface properties of compacts used in Surface Dissolution Imaging (SDI). SDI is useful for determining intrinsic dissolution rate (IDR), an important parameter in early stage drug development. Surface topography, post-compaction and post-SDI...... possible polymorphic changes that may have occurred post-compaction and post-SDI run. IBUs IDR decreased from 0.033mg/min/cm(2) to 0.022mg/min/cm(2) from 10 to 20min, respectively, during the experiment. XRD and DSC showed no form changes during the SDI run. The surface topography images showed...... that a distinct imprint was embossed on the surfaces of some compacts which could affect IDRs. Surface parameter values were associated with the SDI experiments which showed strong correlations with the IDR values. The variable-focus microscope can be used as a complimentary tool in the determination of IDR...

  13. Process fluid cooling system

    International Nuclear Information System (INIS)

    Farquhar, N.G.; Schwab, J.A.

    1977-01-01

    A system of heat exchangers is disclosed for cooling process fluids. The system is particularly applicable to cooling steam generator blowdown fluid in a nuclear plant prior to chemical purification of the fluid in which it minimizes the potential of boiling of the plant cooling water which cools the blowdown fluid

  14. Electron dose-rate conversion factors for external exposure of the skin from uniformly deposited activity on the body surface

    International Nuclear Information System (INIS)

    Kocher, D.C.; Eckerman, K.F.

    1987-01-01

    Dose-rate conversion factors have been calculated for external exposure of the skin from electrons emitted by sources that are deposited uniformly on the body surface. The dose-rate factors are obtained from electron scaled point kernels developed by Berger. The dose-rate factors are calculated at depths of 4, 8, and 40 mg cm-2 below the body surface as recommended by Whitton, and at a depth of 7 mg cm-2 as recommended in ICRP Publication 26 (ICRP77). The dependence of the dose-rate factors at selected depths on the energy of the emitted electrons is displayed. The dose-rate factors for selected radionuclides of potential importance in radiological assessments are tabulated

  15. Johnson screen for cooling water intakes

    International Nuclear Information System (INIS)

    Cook, L.E.

    1978-01-01

    Johnson surface-water screens provide an alternative to vertical traveling screens for power plant cooling water intakes. In this paper, flow field modeling is discussed, and a series of case studies is presented. The hydraulic information obtained is discussed as it applies to the exclusion of biota and debris from cooling water intake systems

  16. The dissociation and recombination rates of CH4through the Ni(111) surface: The effect of lattice motion.

    Science.gov (United States)

    Wang, Wenji; Zhao, Yi

    2017-07-28

    Methane dissociation is a prototypical system for the study of surface reaction dynamics. The dissociation and recombination rates of CH 4 through the Ni(111) surface are calculated by using the quantum instanton method with an analytical potential energy surface. The Ni(111) lattice is treated rigidly, classically, and quantum mechanically so as to reveal the effect of lattice motion. The results demonstrate that it is the lateral displacements rather than the upward and downward movements of the surface nickel atoms that affect the rates a lot. Compared with the rigid lattice, the classical relaxation of the lattice can increase the rates by lowering the free energy barriers. For instance, at 300 K, the dissociation and recombination rates with the classical lattice exceed the ones with the rigid lattice by 6 and 10 orders of magnitude, respectively. Compared with the classical lattice, the quantum delocalization rather than the zero-point energy of the Ni atoms further enhances the rates by widening the reaction path. For instance, the dissociation rate with the quantum lattice is about 10 times larger than that with the classical lattice at 300 K. On the rigid lattice, due to the zero-point energy difference between CH 4 and CD 4 , the kinetic isotope effects are larger than 1 for the dissociation process, while they are smaller than 1 for the recombination process. The increasing kinetic isotope effect with decreasing temperature demonstrates that the quantum tunneling effect is remarkable for the dissociation process.

  17. An insight into Newton's cooling law using fractional calculus

    Science.gov (United States)

    Mondol, Adreja; Gupta, Rivu; Das, Shantanu; Dutta, Tapati

    2018-02-01

    For small temperature differences between a heated body and its environment, Newton's law of cooling predicts that the instantaneous rate of change of temperature of any heated body with respect to time is proportional to the difference in temperature of the body with the ambient, time being measured in integer units. Our experiments on the cooling of different liquids (water, mustard oil, and mercury) did not fit the theoretical predictions of Newton's law of cooling in this form. The solution was done using both Caputo and Riemann-Liouville type fractional derivatives to check if natural phenomena showed any preference in mathematics. In both cases, we find that cooling of liquids has an identical value of the fractional derivative of time that increases with the viscosity of the liquid. On the other hand, the cooling studies on metal alloys could be fitted exactly by integer order time derivative equations. The proportionality constant between heat flux and temperature difference was examined with respect to variations in the depth of liquid and exposed surface area. A critical combination of these two parameters signals a change in the mode of heat transfer within liquids. The equivalence between the proportionality constants for the Caputo and Riemann-Liouville type derivatives is established.

  18. Continuous cooling transformation behaviors of CLAM steel

    International Nuclear Information System (INIS)

    Wu, Qing-sheng; Zheng, Shu-hui; Huang, Qun-ying; Liu, Shao-jun; Han, Yang-yang

    2013-01-01

    The continuous cooling transformation (CCT) behaviors of CLAM (China Low Activation Martensitic) steel were studied, the CCT diagram was constructed, and the influence of cooling rates on the microstructures was also investigated. The microstructures were investigated using optical microscopy (OM) and microhardness tests were also carried out. The results showed that CLAM steel possessed high hardenability and there were ferrite and martensite transformation regions only. The maximum cooling rate to form ferrite microstructure was found to be 10–12 K/min. In order to obtain fully ferrite microstructure, the cooling rate should be lower than 1 K/min. The CCT diagram also gave relevant parameters such as the transformation temperatures, i.e., A c1 , A c3 , M s and M f were 1124 K, 1193 K, 705 K and 593 K, respectively. The diagram made it possible to predict the microstructures and properties of CLAM steel with different cooling rates

  19. Ex vivo investigations of laser auricular cartilage reshaping with carbon dioxide spray cooling in a rabbit model.

    Science.gov (United States)

    Wu, Edward C; Sun, Victor; Manuel, Cyrus T; Protsenko, Dmitriy E; Jia, Wangcun; Nelson, J Stuart; Wong, Brian J F

    2013-11-01

    Laser cartilage reshaping (LCR) with cryogen spray cooling is a promising modality for producing cartilage shape change while reducing cutaneous thermal injury. However, LCR in thicker tissues, such as auricular cartilage, requires higher laser power, thus increasing cooling requirements. To eliminate the risks of freeze injury characteristic of high cryogen spray pulse rates, a carbon dioxide (CO2) spray, which evaporates rapidly from the skin, has been proposed as the cooling medium. This study aims to identify parameter sets which produce clinically significant reshaping while producing minimal skin thermal injury in LCR with CO2 spray cooling in ex vivo rabbit auricular cartilage. Excised whole rabbit ears were mechanically deformed around a cylindrical jig and irradiated with a 1.45-μm wavelength diode laser (fluence 12-14 J/cm(2) per pulse, four to six pulse cycles per irradiation site, five to six irradiation sites per row for four rows on each sample) with concomitant application of CO2 spray (pulse duration 33-85 ms) to the skin surface. Bend angle measurements were performed before and after irradiation, and the change quantified. Surface temperature distributions were measured during irradiation/cooling. Maximum skin surface temperature ranged between 49.0 to 97.6 °C following four heating/cooling cycles. Significant reshaping was achieved with all laser dosimetry values with a 50-70 °C difference noted between controls (no cooling) and irradiated ears. Increasing cooling pulse duration yielded progressively improved gross skin protection during irradiation. CO2 spray cooling may potentially serve as an alternative to traditional cryogen spray cooling in LCR and may be the preferred cooling medium for thicker tissues. Future studies evaluating preclinical efficacy in an in vivo rabbit model are in progress.

  20. Ex vivo investigations of laser auricular cartilage reshaping with carbon dioxide spray cooling in a rabbit model

    Science.gov (United States)

    Wu, Edward C.; Sun, Victor; Manuel, Cyrus T.; Protsenko, Dmitriy E.; Jia, Wangcun; Nelson, J. Stuart; Wong, Brian J. F.

    2014-01-01

    Laser cartilage reshaping (LCR) with cryogen spray cooling is a promising modality for producing cartilage shape change while reducing cutaneous thermal injury. However, LCR in thicker tissues, such as auricular cartilage, requires higher laser power, thus increasing cooling requirements. To eliminate the risks of freeze injury characteristic of high cryogen spray pulse rates, a carbon dioxide (CO2) spray, which evaporates rapidly from the skin, has been proposed as the cooling medium. This study aims to identify parameter sets which produce clinically significant reshaping while producing minimal skin thermal injury in LCR with CO2 spray cooling in ex vivo rabbit auricular cartilage. Excised whole rabbit ears were mechanically deformed around a cylindrical jig and irradiated with a 1.45-μm wavelength diode laser (fluence 12–14 J/cm2 per pulse, four to six pulse cycles per irradiation site, five to six irradiation sites per row for four rows on each sample) with concomitant application of CO2 spray (pulse duration 33–85 ms) to the skin surface. Bend angle measurements were performed before and after irradiation, and the change quantified. Surface temperature distributions were measured during irradiation/cooling. Maximum skin surface temperature ranged between 49.0 to 97.6 °C following four heating/cooling cycles. Significant reshaping was achieved with all laser dosimetry values with a 50–70 °C difference noted between controls (no cooling) and irradiated ears. Increasing cooling pulse duration yielded progressively improved gross skin protection during irradiation. CO2 spray cooling may potentially serve as an alternative to traditional cryogen spray cooling in LCR and may be the preferred cooling medium for thicker tissues. Future studies evaluating preclinical efficacy in an in vivo rabbit model are in progress. PMID:23307439

  1. Variability in surface water properties of the southeastern South Atlantic Ocean related to the Miocene Cooling Events, evidence from calcareous dinoflagellate cysts.

    Science.gov (United States)

    Heinrich, S.; Zonneveld, K. A. F.; Willems, H.

    2009-04-01

    The middle- and upper Miocene represent major climatic shifts to colder global temperatures. These periods of cooling (Mi-Events) were characterized by oxygen isotopic shifts that have been related to size changes of the Antarctic and Arctic ice-sheets (e.g. Miller et al., 1991, St. John, 2008). The start and development of the Antarctic Circumpolar Current (ACC) during this time-interval is of major interest, as it changed the atmospheric and oceanic circulation pattern which led to the initiation of upwelling off the south western African coast (Paulsen et al., 2007). However, the complex interaction between the initiation and development of the upwelling in the western South Atlantic and its interaction with the evolution of the Antarctic Circumpolar Current as well as the built-up of the Antarctic ice-sheet is far from being fully understood. We want to improve the understanding of these processes by establishing a detailed palaeoceanographic reconstruction of the southeastern South Atlantic Ocean on the basis of calcareous dinoflagellate cyst associations. Within this study 53 samples were taken from sediment core ODP 175 1085A off the coast of Namibia and investigated by defining the calcareous dinoflagellate cyst assemblage. The general cooling trend during the middle- and upper Miocene is clearly reflected in the dinocyst record by the decrease of species adapted to warm water conditions (Calciodinellum albatrosianum and Thoracosphaera heimii) and the appearance and increase of Caracomia arctica after ~ 11.1 Ma. C. arctica is a cold water species which today is only present south of the polar front. The concentration of C. arctica varies with a cyclicity of about 200-400 kyrs which reflects an eccentricity signal. We assume that observed changes in association such as the appearance of C. arctica can either be related to the initiation of the upwelling activity in the region, which is suggested to occur at ~11.6 Ma (Paulsen & Bickert 2007), or might be the

  2. Recent Development in Turbine Blade Film Cooling

    Directory of Open Access Journals (Sweden)

    Je-Chin Han

    2001-01-01

    Full Text Available Gas turbines are extensively used for aircraft propulsion, land-based power generation, and industrial applications. Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature (RIT. The current RIT level in advanced gas turbines is far above the .melting point of the blade material. Therefore, along with high temperature material development, a sophisticated cooling scheme must be developed for continuous safe operation of gas turbines with high performance. Gas turbine blades are cooled internally and externally. This paper focuses on external blade cooling or so-called film cooling. In film cooling, relatively cool air is injected from the inside of the blade to the outside surface which forms a protective layer between the blade surface and hot gas streams. Performance of film cooling primarily depends on the coolant to mainstream pressure ratio, temperature ratio, and film hole location and geometry under representative engine flow conditions. In the past number of years there has been considerable progress in turbine film cooling research and this paper is limited to review a few selected publications to reflect recent development in turbine blade film cooling.

  3. Performance enhancement of PV cells through micro-channel cooling

    Directory of Open Access Journals (Sweden)

    Muzaffar Ali

    2015-11-01

    Full Text Available Efficiency of a PV cell is strongly dependent on its surface temperature. The current study is focused to achieve maximum efficiency of PV cells even in scorching temperatures in hot climates like Pakistan where the cell surface temperatures can even rise up to around 80 ℃. The study includes both the CFD and real time experimental investigations of a solar panel using micro channel cooling. Initially, CFD analysis is performed by developing a 3D model of a Mono-Crystalline cell with micro-channels to analyze cell surface temperature distribution at different irradiance and water flow rates. Afterwards, an experimental setup is developed for performance investigations under the real conditions of an open climate of a Pakistan's city, Taxila. Two 35W panels are manufactured for the experiments; one is based on the standard manufacturing procedure while other cell is developed with 4mm thick aluminum sheet having micro-channels of cross-section of 1mm by 1mm. The whole setup also includes different sensors for the measurement of solar irradiance, cell power, surface temperature and water flow rates. The experimental results show that PV cell surface temperature drop of around 15 ℃ is achieved with power increment of around 14% at maximum applied water flow rate of 3 LPM. Additionally, a good agreement is also found between CFD and experimental results. Therefore, that study clearly shows that a significant performance improvement of PV cells can be achieved through the proposed cell cooling technique.

  4. Validity of the formalism of calculation in surface TG-43 brachytherapy high dose rate

    International Nuclear Information System (INIS)

    Granero, D.; Perez-Calatayud, J.; Vijande, J.; Ballester, F.; Rivard, M. J.

    2013-01-01

    The purpose of this work is to evaluate the clinical implications and limitations in implant surface with a source of HDR very close or in contact with the surface of the skin, also studied the effect of bolus on the implant. The two available radionuclides have been studied commercially in HDR, Ir-192 and Co-60 units. (Author)

  5. Research on the effect of coverage rate on the surface quality in laser direct writing process

    Science.gov (United States)

    Pan, Xuetao; Tu, Dawei

    2017-07-01

    Direct writing technique is usually used in femtosecond laser two-photon micromachining. The size of the scanning step is an important factor affecting the surface quality and machining efficiency of micro devices. According to the mechanism of two-photon polymerization, combining the distribution function of light intensity and the free radical concentration theory, we establish the mathematical model of coverage of solidification unit, then analyze the effect of coverage on the machining quality and efficiency. Using the principle of exposure equivalence, we also obtained the analytic expressions of the relationship among the surface quality characteristic parameters of microdevices and the scanning step, and carried out the numerical simulation and experiment. The results show that the scanning step has little influence on the surface quality of the line when it is much smaller than the size of the solidification unit. However, with increasing scanning step, the smoothness of line surface is reduced rapidly, and the surface quality becomes much worse.

  6. Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob

    2009-01-01

    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various...... transition-metal surfaces and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system with parameters obtained from the excited-state potential energy surface and show that this model can describe desorption dynamics...... in both the DIET and DIMET regimes and reproduce the power-law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong....

  7. Evaluation method of gas leakage rate from transportation casks of radioactive materials (gas leakage rates from scratches on O-ring surface)

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Li Ninghua; Asano, Ryoji; Kawa, Tsunemichi

    2004-01-01

    A sealing function is essential for transportation and/or storage casks of radioactive materials under both normal and accidental operating conditions in order to prevent radioactive materials from being released into the environment. In the safety analysis report, the release rate of radioactive materials into the environment is evaluated using the correlations specified in the ANSI N14.5, 1987. The purposes of the work are to reveal the underlying problems on the correlations specified in the ANSI N14.5 related to gas leakage rates from a scratch on O-ring surface and from multi-leak paths, to offer a data base to study the evaluation method of the leakage rate and to propose the evaluation method. In this paper, the following insights were obtained and clarified: 1. If a characteristic value of a leak path is defined as D 4 /a ('D' is the diameter and 'a' is the length), a scratch on the O-ring surface can be evaluated as a circular tube. 2. It is proper to use the width of O-ring groove on the flange as the leak path length for elastomer O-rings. 3. Gas leakage rates from multi leak paths of the transportation cask can be evaluated in the same manner as a single leak path if an effective D4/a is introduced. (author)

  8. Expressions for the evaporation of sessile liquid droplets incorporating the evaporative cooling effect.

    Science.gov (United States)

    Wang, Yilin; Ma, Liran; Xu, Xuefeng; Luo, Jianbin

    2016-12-15

    The evaporation along the surface of pinned, sessile droplets is investigated numerically by using the combined field approach. In the present model, the evaporative cooling at the droplet surface which leads to a reduction in the evaporation is taken into account. Simple, yet accurate analytical expressions for the local evaporation flux and for the total evaporation rate of sessile droplets are obtained. The theoretical analyses indicate that the reduction in the evaporation becomes more pronounced as the evaporative cooling number Ec increases. The results also reveal that the variation of total evaporation rate with contact angle will change its trend as the intensity of the evaporative cooling changes. For small values of Ec, the total evaporation rate increases with the contact angle, the same as predicted by Deegan et al. and by Hu and Larson in their isothermal models in which the evaporative cooling is neglected. Contrarily, when the evaporative cooling effect is strong enough, the total evaporation rate will decrease as the contact angle increases. The present theory is corroborated experimentally, and found in good agreement with the expressions proposed by Hu and Larson in the limiting isothermal case. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Restaurant Food Cooling Practices†

    Science.gov (United States)

    BROWN, LAURA GREEN; RIPLEY, DANNY; BLADE, HENRY; REIMANN, DAVE; EVERSTINE, KAREN; NICHOLAS, DAVE; EGAN, JESSICA; KOKTAVY, NICOLE; QUILLIAM, DANIELA N.

    2017-01-01

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

  10. Concrete spent fuel storage casks dose rates

    International Nuclear Information System (INIS)

    Bace, M.; Jecmenica, R.; Trontl, K.

    1998-01-01

    Our intention was to model a series of concrete storage casks based on TranStor system storage cask VSC-24, and calculate the dose rates at the surface of the casks as a function of extended burnup and a prolonged cooling time. All of the modeled casks have been filled with the original multi-assembly sealed basket. The thickness of the concrete shield has been varied. A series of dose rate calculations for different burnup and cooling time values have been performed. The results of the calculations show rather conservative original design of the VSC-24 system, considering only the dose rate values, and appropriate design considering heat rejection.(author)

  11. Cooled spool piston compressor

    Science.gov (United States)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  12. Flow distribution analysis on the cooling tube network of ITER thermal shield

    International Nuclear Information System (INIS)

    Nam, Kwanwoo; Chung, Wooho; Noh, Chang Hyun; Kang, Dong Kwon; Kang, Kyoung-O; Ahn, Hee Jae; Lee, Hyeon Gon

    2014-01-01

    Thermal shield (TS) is to be installed between the vacuum vessel or the cryostat and the magnets in ITER tokamak to reduce the thermal radiation load to the magnets operating at 4.2K. The TS is cooled by pressurized helium gas at the inlet temperature of 80K. The cooling tube is welded on the TS panel surface and the composed flow network of the TS cooling tubes is complex. The flow rate in each panel should be matched to the thermal design value for effective radiation shielding. This paper presents one dimensional analysis on the flow distribution of cooling tube network for the ITER TS. The hydraulic cooling tube network is modeled by an electrical analogy. Only the cooling tube on the TS surface and its connecting pipe from the manifold are considered in the analysis model. Considering the frictional factor and the local loss in the cooling tube, the hydraulic resistance is expressed as a linear function with respect to mass flow rate. Sub-circuits in the TS are analyzed separately because each circuit is controlled by its own control valve independently. It is found that flow rates in some panels are insufficient compared with the design values. In order to improve the flow distribution, two kinds of design modifications are proposed. The first one is to connect the tubes of the adjacent panels. This will increase the resistance of the tube on the panel where the flow rate is excessive. The other design suggestion is that an orifice is installed at the exit of tube routing where the flow rate is to be reduced. The analysis for the design suggestions shows that the flow mal-distribution is improved significantly

  13. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.; Klopfer, D.C.

    1990-08-01

    Protective barriers have been identified as integral components of plans to isolate defense waste on the Hanford Site. The use of natural materials to construct protective barriers over waste site is being considered. Design requirements for protective barriers include preventing exposure of buried waste, and restricting penetration or percolation of surface waters through the waste zone. Studies were initiated to evaluate the effects of wind erosion on candidate protective barrier surfaces. A wind tunnel was used to provide controlled erosive stresses and to investigate the erosive effects of wind forces on proposed surface layers for protective barriers. Mixed soil and gravel surfaces were prepared and tested for resistance to wind erosion at the Pacific Northwest Laboratory Aerosol Wind Tunnel Research Facility. These tests were performed to investigate surface deflation caused by suspension of soil from various surface layer configurations and to provide a comparison of the relative resistance of the different surfaces to wind erosion. Planning, testing, and analyzing phases of this wind erosion project were coordinated with other tasks supporting the development of protective barriers. These tasks include climate-change predictions, field studies and modeling efforts. This report provides results of measurements of deflation caused by wind forces over level surfaces. Section 2.0 reviews surface layer characteristics and previous relevant studies on wind erosion, describes effects of erosion, and discusses wind tunnel modeling. Materials and methods of the wind tunnel tests are discussed in Section 3.0. Results and discussion are presented in Section 4.0, and conclusions and recommendations Section 5.0. 53 refs., 29 figs., 7 tabs.

  14. New cooling regulation technology of secondary cooling station in DCS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan; Yan, Jun-wei; Zhu, Dong-sheng; Liu, Fei-long; Lei, Jun-xi [The Key Lab of Enhanced Heat Transfer and Energy Conservation of Ministry of Education, School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China); Liang, Lie-quan [The Key Lab of E-Commerce Market Application Technology of Guangdong Province, Guangdong University of Business Studies, Guangzhou 510320 (China)

    2008-07-01

    In this paper, a kind of new control technology of secondary cooling station (constant flow rate/variable temperature difference) in district cooling system (DCS) is proposed in view of serial consequences including low efficiency and high operating cost caused by low temperature of supply water in DCS. This technology has been applied in DCS of Guangzhou University City. The result has already indicated that such technology can increase the supply and return temperatures of buildings, return water temperature of primary side in the plate heat exchanger unit, moreover, the efficiency of both the chiller and the whole system are improved significantly. (author)

  15. Evaluation of the contribution of contamination of radiotherapy room surfaces in the measure of exposure rate of radioiodine therapy patients

    International Nuclear Information System (INIS)

    Campos, Rafael Ferreira

    2015-01-01

    The contamination of radiotherapy room surfaces is significant and the measures of patient exposure rate are held on the fourth dependencies, relevant questions are raised: the background radiation of the room stay high due to surface contamination, may interfere with the rate of patient exposure at the time of its release? The monitoring site is important to determine whether the patient will be released? The value of the deal activity and the clinical condition of the patient may increase the contamination, influencing the monitoring results? This paper aims to conduct a quantitative analysis of surface contamination of the contribution of therapeutic room at the time is monitored exposure rate from inpatient. Measurements were made regarding the hospitalization of 32 patients with different doses administered activity, age and of both genders. The measurements were performed in the therapeutic rooms at the hospital Brotherhood Santa Casa de Misericordia de Sao Paulo. Exposure rate measurements were performed at the center of the room at 1 meter of the patient on the day of its release. After his release and prior to decontamination, measurements were performed at predetermined landmarks within the therapeutic room. The results revealed that on average background radiation, high due to surface contamination contributes only 2% of the patient dose rate. It can be considered that even with influence of contamination of surfaces, this is insignificant to determine if the patient may or may not be released. This study suggests that the site in which monitoring occurs exposure rate of the patient should not be decisive for liberation thereof. (author)

  16. Newton's law of cooling revisited

    International Nuclear Information System (INIS)

    Vollmer, M

    2009-01-01

    The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer from any object to its surrounding is not only due to conduction and convection but also due to radiation. The latter does not vary linearly with temperature difference, which leads to deviations from Newton's law. This paper presents a theoretical analysis of the cooling of objects with a small Biot number. It is shown that Newton's law of cooling, i.e. simple exponential behaviour, is mostly valid if temperature differences are below a certain threshold which depends on the experimental conditions. For any larger temperature differences appreciable deviations occur which need the complete nonlinear treatment. This is demonstrated by results of some laboratory experiments which use IR imaging to measure surface temperatures of solid cooling objects with temperature differences of up to 300 K.

  17. A novel pulse isotopic exchange technique for rapid determination of the oxygen surface exchange rate of oxide ion conductors

    NARCIS (Netherlands)

    Bouwmeester, Henricus J.M.; Song, Chunlin; Song, C.; Zhu, J.J.; van Sint Annaland, M.; Yi, Jianxin; Boukamp, Bernard A.

    2009-01-01

    We demonstrate the use of a novel pulse 18O–16O isotopic exchange technique for the rapid determination of the oxygen surface exchange rate of oxide ion conductors while simultaneously providing insight into the mechanism of the oxygen exchange reaction, which contributes to the efficient

  18. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs.

  19. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs

  20. Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

    Science.gov (United States)

    Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

    2018-04-01

    Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

  1. Increasing photovoltaic panel power through water cooling technique

    Directory of Open Access Journals (Sweden)

    Calebe Abrenhosa Matias

    2017-02-01

    Full Text Available This paper presents the development of a cooling apparatus using water in a commercial photovoltaic panel in order to analyze the increased efficiency through decreased operating temperature. The system enables the application of reuse water flow, at ambient temperature, on the front surface of PV panel and is composed of an inclined plane support, a perforated aluminum profile and a water gutter. A luminaire was specially developed to simulate the solar radiation over the module under test in a closed room, free from the influence of external climatic conditions, to carry out the repetition of the experiment in controlled situations. The panel was submitted to different rates of water flow. The best water flow rate was of 0.6 L/min and net energy of 77.41Wh. Gain of 22.69% compared to the panel without the cooling system.

  2. ATLAS' major cooling project

    CERN Document Server

    2005-01-01

    In 2005, a considerable effort has been put into commissioning the various units of ATLAS' complex cryogenic system. This is in preparation for the imminent cooling of some of the largest components of the detector in their final underground configuration. The liquid helium and nitrogen ATLAS refrigerators in USA 15. Cryogenics plays a vital role in operating massive detectors such as ATLAS. In many ways the liquefied argon, nitrogen and helium are the life-blood of the detector. ATLAS could not function without cryogens that will be constantly pumped via proximity systems to the superconducting magnets and subdetectors. In recent weeks compressors at the surface and underground refrigerators, dewars, pumps, linkages and all manner of other components related to the cryogenic system have been tested and commissioned. Fifty metres underground The helium and nitrogen refrigerators, installed inside the service cavern, are an important part of the ATLAS cryogenic system. Two independent helium refrigerators ...

  3. Reductions in soil surface albedo as a function of biochar application rate: implications for global radiative forcing

    International Nuclear Information System (INIS)

    Verheijen, Frank G A; Bastos, Ana Catarina; Keizer, Jan Jacob; Jeffery, Simon; Van der Velde, Marijn; Penížek, Vít; Beland, Martin

    2013-01-01

    Biochar can be defined as pyrolysed (charred) biomass produced for application to soils with the aim of mitigating global climate change while improving soil functions. Sustainable biochar application to soils has been estimated to reduce global greenhouse gas emissions by 71–130 Pg CO 2 -C e over 100 years, indicating an important potential to mitigate climate change. However, these estimates ignored changes in soil surface reflection by the application of dark-coloured biochar. Through a laboratory experiment we show a strong tendency for soil surface albedo to decrease as a power decay function with increasing biochar application rate, depending on soil moisture content, biochar application method and land use. Surface application of biochar resulted in strong reductions in soil surface albedo even at relatively low application rates. As a first assessment of the implications for climate change mitigation of these biochar–albedo relationships, we applied a first order global energy balance model to compare negative radiative forcings (from avoided CO 2 emissions) with positive radiative forcings (from reduced soil surface albedos). For a global-scale biochar application equivalent to 120 t ha −1 , we obtained reductions in negative radiative forcings of 5 and 11% for croplands and 11 and 23% for grasslands, when incorporating biochar into the topsoil or applying it to the soil surface, respectively. For a lower global biochar application rate (equivalent to 10 t ha −1 ), these reductions amounted to 13 and 44% for croplands and 28 and 94% for grasslands. Thus, our findings revealed the importance of including changes in soil surface albedo in studies assessing the net climate change mitigation potential of biochar, and we discuss the urgent need for field studies and more detailed spatiotemporal modelling. (letter)

  4. Sustainable cooling method for machining titanium alloy

    International Nuclear Information System (INIS)

    Boswell, B; Islam, M N

    2016-01-01

    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. (paper)

  5. Muon cooling channels

    CERN Document Server

    Eberhard-K-Kei

    2003-01-01

    A procedure uses the equations that govern ionization cooling, and leads to the most important parameters of a muon cooling channel that achieves assumed performance parameters. First, purely transverse cooling is considered, followed by both transverse and longitudinal cooling in quadrupole and solenoid channels. Similarities and differences in the results are discussed in detail, and a common notation is developed. Procedure and notation are applied to a few published cooling channels. The parameters of the cooling channels are derived step by step, starting from assumed values of the initial, final and equilibrium emittances, both transverse and longitudinal, the length of the cooling channel, and the material properties of the absorber. The results obtained include cooling lengths and partition numbers, amplitude functions and limits on the dispersion at the absorber, length, aperture and spacing of the absorber, parameters of the RF system that achieve the longitudinal amplitude function and bucket area ...

  6. Study of magnetized accretion flow with cooling processes

    Science.gov (United States)

    Singh, Kuldeep; Chattopadhyay, Indranil

    2018-02-01

    We have studied shock in magnetized accretion flow/funnel flow in case of neutron star with bremsstrahlung cooling and cyclotron cooling. All accretion solutions terminate with a shock close to the neutron star surface, but at some regions of the parameter space, it also harbours a second shock away from the star surface. We have found that cyclotron cooling is necessary for correct accretion solutions which match the surface boundary conditions.

  7. A Numerical Analysis of Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models