WorldWideScience

Sample records for barometric pressure conditions

  1. Influence of Barometric Pressure Changes on Ventilation Conditions in Deep Mines

    Science.gov (United States)

    Wasilewski, Stanis?aw

    2014-10-01

    Barometric air pressure and its changes have a critical impact on ventilation conditions in the underground workings of deep mines. Changes in pressure are particularly important because they are responsible for the transient states of ventilation conditions, therefore, assessing the scale of pressure change is essential. Unfortunately, previously for many years in the Polish mining industry barometric pressure was recorded only on tapes of mechanical barographs by the ventilation department on the surface and therefore such dependencies of methane concentration due to barometric pressure changes have not been properly documented. Today, after the implementation in mines of instruments enabling the monitoring of absolute pressure in the workings of mines (Wasilewski, 2009) the conditions have been created to study the influence of pressure changes on changes of air parameters in the mine workings. Barometric pressure changes were observed and recorded over a course of approximately two years using monitoring system that utilized high accuracy pressure sensors on the surface and in selected workings of an underground mine. This paper presents a statistical analysis of the data that we generated from assessing pressure changes on the surface and at selected underground points in the mine. In the article, which presents the results of the first part of the study, some examples of when significant changes in pressure prior to the tragic events, which were not accompanied by changes in the methane concentration in mine workings, will also be shown. Interestingly, we found that the relationship between methane ignitions and explosions in longwall gob mined via the cave-in method is associated with changes in the barometric pressure. Several instances of methane ignitions and explosions in the gob of cave-in longwalls in recent years were compared with background barometric pressure changes. Research carried out in within the strategic project "Improving work safety in the mines" allowed to record air parameters changes inside the gob of longwalls and show the influence of pressure changes on changes in methane and oxygen concentration in the gob, which will be shown in the second part of the article to be published in the near future.

  2. Barometric pressure transient testing applications at the Nevada Test Site. Nuclear chimney analysis. Final report

    International Nuclear Information System (INIS)

    Investigations of barometric pressure testing of NTS nuclear chimneys were reviewed. This review includes the models used in the interpretation, methods of analysis, and results. Analytic and semi-analytic models were presented and applied to both historical data and new data taken for this current project. An interpretation technique based on non-linear least squares methods was used to analyze this data in terms of historic and more recent chimney models. Finally, a detailed discussion of radioactive gas transport due to surface barometric pressure fluctuations was presented. This mechanism of transport, referred to as ''barometric pumping,'' is presented in terms of conditions likely to be encountered at the NTS. The report concludes with a discussion of the current understanding of gas flow properties in the alluvial and volcanic areas of the NTS, and suggestions for future efforts directed toward increasing this understanding are presented

  3. Barometric pressure transient testing applications at the Nevada Test Site. Nuclear chimney analysis. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, J.M.

    1985-12-01

    Investigations of barometric pressure testing of NTS nuclear chimneys were reviewed. This review includes the models used in the interpretation, methods of analysis, and results. Analytic and semi-analytic models were presented and applied to both historical data and new data taken for this current project. An interpretation technique based on non-linear least squares methods was used to analyze this data in terms of historic and more recent chimney models. Finally, a detailed discussion of radioactive gas transport due to surface barometric pressure fluctuations was presented. This mechanism of transport, referred to as ''barometric pumping,'' is presented in terms of conditions likely to be encountered at the NTS. The report concludes with a discussion of the current understanding of gas flow properties in the alluvial and volcanic areas of the NTS, and suggestions for future efforts directed toward increasing this understanding are presented.

  4. Barometric pressures at extreme altitudes on Mt. Everest: physiological significance.

    Science.gov (United States)

    West, J B; Lahiri, S; Maret, K H; Peters, R M; Pizzo, C J

    1983-05-01

    Barometric pressures were measured on Mt. Everest from altitudes of 5,400 (base camp) to 8,848 m (summit) during the American Medical Research Expedition to Everest. Measurements at 5,400 m were made with a mercury barometer, and above this most of the pressures were obtained with an accurate crystal-sensor barometer. The mean daily pressures were 400.4 +/- 2.7 (SD) Torr (n = 35) at 5,400 m, 351.0 +/- 1.0 Torr (n = 16) at 6,300 m, 283.6 +/- 1.5 Torr (n = 6) at 8,050 m, and 253.0 Torr (n = 1) at 8,848 m. All these pressures are considerably higher than those predicted from the ICAO Standard Atmosphere. The chief reason is that pressures at altitudes between 2 and 16 km are latitude dependent, being higher near the equator because of the large mass of cold air in the stratosphere of that region. Data from weather balloons show that the pressure at the altitude of the summit of Mt. Everest varies considerably with season, being about 11.5 Torr higher in midsummer than in midwinter. Although the mountain has been climbed without supplementary O2, the very low O2 partial pressure at the summit means that it is at the limit of man's tolerance, and even day-by-day variations in barometric pressure apparently affect maximal O2 uptake. PMID:6863078

  5. Barometric pressure transient testing applications at the Nevada Test Site: formation permeability analysis. Final report

    International Nuclear Information System (INIS)

    The report evaluates previous investigations of the gas permeability of the rock surrounding emplacement holes at the Nevada Test Site. The discussion sets the framework from which the present uncertainty in gas permeability can be overcome. The usefulness of the barometric pressure testing method has been established. Flow models were used to evaluate barometric pressure transients taken at NTS holes U2fe, U19ac and U20ai. 31 refs., 103 figs., 18 tabs

  6. Barometric pressure transient testing applications at the Nevada Test Site: formation permeability analysis. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, J.M.

    1984-12-01

    The report evaluates previous investigations of the gas permeability of the rock surrounding emplacement holes at the Nevada Test Site. The discussion sets the framework from which the present uncertainty in gas permeability can be overcome. The usefulness of the barometric pressure testing method has been established. Flow models were used to evaluate barometric pressure transients taken at NTS holes U2fe, U19ac and U20ai. 31 refs., 103 figs., 18 tabs. (ACR)

  7. Insights into aquifer vulnerability and potential recharge zones from the borehole response to barometric pressure changes

    Science.gov (United States)

    El Araby, Mahmoud; Odling, Noelle; Clark, Roger; West, Jared

    2010-05-01

    Borehole water levels fluctuate in response to deformation of the surrounding aquifer caused by surface loading due to barometric pressure or strain caused by Earth and ocean tides. The magnitude and nature of this response mainly depend on the hydraulic properties of the aquifer and overlying units and borehole design. Thus water level responses reflect the effectiveness of a confining unit as a protective layer against aquifer contamination (and therefore groundwater vulnerability) and to potential aquifer recharge/discharge zones. In this study, time series of borehole water levels and barometric pressure are being investigated using time series analysis and signal processing techniques with the aim of developing a methodology for assessing recharge/discharge distribution and groundwater vulnerability in the confined/semi-confined part of the Chalk aquifer in East Yorkshire, UK. The chalk aquifer in East Yorkshire is an important source for industrial and domestic water supply. The aquifer water quality is threatened by surface pollution particularly by nitrates from agricultural fertilizers. The confined/semi-confined part of this aquifer is covered by various types of superficial deposits resulting in a wide range of the aquifer's degree of confinement. A number of boreholes have been selected for monitoring to cover all these various types of confining units. Automatic pressure transducers are installed to record water levels and barometric pressure measurements at each borehole on 15 minutes recording intervals. In strictly confined aquifers, borehole water level response to barometric pressure is an un-drained instantaneous response and is a constant fraction of the barometric pressure changes. This static confined constant is called the barometric efficiency which can be estimated simply by the slope of a regression plot of water levels versus barometric pressure. However, in the semi confined aquifer case this response is lagged due to water movement between the aquifer and the confining layer. In this case the static constant barometric efficiency is not applicable and the response is represented by a barometric response function which reflects the timing and frequency of the barometric pressure loading. In this study, the barometric response function is estimated using de-convolution techniques both in the time domain (least squares regression de-convolution) and in the frequency domain (discrete Fourier transform de-convolution). In order to estimate the barometric response function, borehole water level fluctuations due to factors other than barometric pressure should be removed (de-trended) as otherwise they will mask the response relation of interest. It is shown from the collected borehole data records that the main four factors other than barometric pressure contribute to borehole water level fluctuations. These are the rainfall recharge, Earth tides, sea tides and pumping activities close to the borehole location. Due to the highly variable nature of the UK weather, rainfall recharge shows a wide variation throughout the winter and summer seasons. This gives a complicated recharge signal over a wide range of frequencies which must be de-trended from the borehole water level data in order to estimate the barometric response function. Methods for removing this recharge signal are developed and discussed. Earth tides are calculated theoretically at each borehole location taking into account oceanic loading effects. Ocean tide effects on water levels fluctuations are clear for the boreholes located close to the coast. A Matlab code has been designed to calculate and de-trend the periodic fluctuations in borehole water levels due to Earth and ocean tides using the least squares regression technique based on a sum of sine and cosine fitting model functions. The program results have been confirmed using spectral analysis techniques.

  8. The Effects of Temperature, Humidity and Barometric Pressure on Short Sprint Race Times

    CERN Document Server

    Mureika, J R

    2006-01-01

    A numerical model of 100 m and 200 m world class sprinting performances is modified using standard hydrodynamic principles to include effects of air temperature, pressure, and humidity levels on aerodynamic drag. The magnitude of the effects are found to be dependent on wind speed. This implies that differing atmospheric conditions can yield slightly different corrections for the same wind gauge reading. In the absence of wind, temperature is found to induce the largest variation in times (0.01 s per $10\\dc$ increment in the 100 m), while relative humidity contributes the least (under 0.01 s for all realistic conditions for 100 m). Barometric pressure variations at a particular venue can also introduce fluctuations in performance times on the order of a 0.01 s for this race. The combination of all three variables is essentially additive, and is more important for head-wind conditions that for tail-winds. As expected, calculated corrections in the 200 m are magnified due to the longer duration of the race. The...

  9. Investigation of relationship between barometric pressure and coal and gas outburst events in underground coal mining

    Science.gov (United States)

    Yönet, Sinem; Esen, Olgun; Fi?ne, Abdullah

    2015-04-01

    Coal and gas outburst is a serious risk which occurs during the mine production. This accident results both ejection of high volumes of gas and high amount of coal into the mine production area, and death of mining workers for many years in Turkey. Outburst of gas, coal and rock can be defined as sudden release of coal and rock accompanied by large quantities of gas into the working face or other mine workings. It is a phenomena that influenced by geological structure such as folds, joints of rocks or coal seams, is also still investigated for many years. Zonguldak Coal Basin is the main part of the Upper Carboniferous bituminous coal basin of Turkey. Much of the bituminous coal mining has thus been concentrated in the Zonguldak Basin which is located on the Black Sea coast. The coal field has been disturbed by tectonic activity, first by Hercynian and later by Alpine orogenesis resulting in folding and faulting of strata. This formation has a complex structural geology which consists mostly fault zones, anticlinal and syncline strata and because of this a large amount of methane gases are adsorbed or accumulated in strata or in coal fractures, pores and micropores. There are 5 Collieries exists in Zonguldak Coalfield and coal and gas outbursts were occurred only in two collieries such as Karadon and Kozlu Mines. In addition at a number of 90 coal and gas outburst events were experienced in these collieries. Based on the analysis of data, oscillation at barometric pressure and temperature values at the location of Kozlu and Karadon Mines were seen when coal and gas outburst events were occurred. In this study, barometric pressure and temperature changes are investigated at Kozlu and Karadon Mines. Also the relationship between the variation at temperature with barometric pressure and coal and gas outbursts are evaluated. It can be understand that this investigation depends to field observations and macroscopic considerations and on the purpose of predicting the coal and gas outburst event earlier.

  10. Torricelli and the Ocean of Air: The First Measurement of Barometric Pressure

    Science.gov (United States)

    2013-01-01

    The recognition of barometric pressure was a critical step in the development of environmental physiology. In 1644, Evangelista Torricelli described the first mercury barometer in a remarkable letter that contained the phrase, “We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight.” This extraordinary insight seems to have come right out of the blue. Less than 10 years before, the great Galileo had given an erroneous explanation for the related problem of pumping water from a deep well. Previously, Gasparo Berti had filled a very long lead vertical tube with water and showed that a vacuum formed at the top. However, Torricelli was the first to make a mercury barometer and understand that the mercury was supported by the pressure of the air. Aristotle stated that the air has weight, although this was controversial for some time. Galileo described a method of measuring the weight of the air in detail, but for reasons that are not clear his result was in error by a factor of about two. Torricelli surmised that the pressure of the air might be less on mountains, but the first demonstration of this was by Blaise Pascal. The first air pump was built by Otto von Guericke, and this influenced Robert Boyle to carry out his classical experiments of the physiological effects of reduced barometric pressure. These were turning points in the early history of high-altitude physiology. PMID:23455767

  11. Torricelli and the ocean of air: the first measurement of barometric pressure.

    Science.gov (United States)

    West, John B

    2013-03-01

    The recognition of barometric pressure was a critical step in the development of environmental physiology. In 1644, Evangelista Torricelli described the first mercury barometer in a remarkable letter that contained the phrase, "We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight." This extraordinary insight seems to have come right out of the blue. Less than 10 years before, the great Galileo had given an erroneous explanation for the related problem of pumping water from a deep well. Previously, Gasparo Berti had filled a very long lead vertical tube with water and showed that a vacuum formed at the top. However, Torricelli was the first to make a mercury barometer and understand that the mercury was supported by the pressure of the air. Aristotle stated that the air has weight, although this was controversial for some time. Galileo described a method of measuring the weight of the air in detail, but for reasons that are not clear his result was in error by a factor of about two. Torricelli surmised that the pressure of the air might be less on mountains, but the first demonstration of this was by Blaise Pascal. The first air pump was built by Otto von Guericke, and this influenced Robert Boyle to carry out his classical experiments of the physiological effects of reduced barometric pressure. These were turning points in the early history of high-altitude physiology. PMID:23455767

  12. Barometric pressure, dry bulb temperature and vapor pressure at the lowest terrestrial site on earth, Dead Sea basin, Neve Zohar, Israel

    Science.gov (United States)

    Kudish, A. I.; Evseev, E. G.

    2006-03-01

    The Dead Sea basin is located at the lowest terrestrial site on the earth and, thereby, has the tallest atmospheric air column above its surface. Consequently, the Dead Sea basin is expected, a priori, to have the highest terrestrial barometric pressure and, thereby, the highest molecular oxygen density on the earth. The barometric pressure and dry bulb temperature have been monitored continuously at Neve Zohar, located on the western shore of the Dead Sea, since January 1995. The monthly average daily barometric pressure values exceed normal atmospheric pressure by a maximum of 4.83 hPa (4.77%) and a minimum of 33.1 hPa (3.26%) for December and July, respectively. This increase in barometric pressure can serve as a simple way to improve arterial oxygenation in hypoxemic patients. As a result, a number of research projects have been initiated on the treatment of patients suffering from pulmonary and cardiac diseases at the Dead Sea basin. The hourly barometric pressure data with regard to both its diurnal and monthly variation and the correlation between barometric pressure and dry bulb temperature will be analyzed.

  13. Simulation and observation of ESF tunnell effects on barometric conditions

    International Nuclear Information System (INIS)

    UE-25 ONC No.1 and USW NRG-4 boreholes were instrumented to evaluate pneumatic conditions in response to natural and man-made fluctuations at the surface and subsurface environments during site characterization activities. Nye County has several concerns, some of which are as follows: (1) Can pneumatic properties of the rocks be characterized and the pneumatic potential be defined adequately? (2) Do site characterization activities, such as ESF tunneling, cause irreversible disturbances that could have potential adverse effects? (3) Is there pertinent information that should be collected before the repository block is disturbed by site-characterization activities? The results of the present study demonstrate that the potential for air invasion of the formations is greater than previously thought. Several one-dimensional and simple simulations were performed to obtain estimate of the pneumatic conductivity of the formations

  14. Change in the barometric coefficient of the neutron component of cosmic rays depending on the level of atmospheric pressure

    Science.gov (United States)

    Glonti, N. Ia.

    1985-08-01

    The dependence of the barometric coefficient (BC) of the neutron component on changes in atmospheric pressure is investigated on the basis of atmospheric pressure and cosmic ray data from the Moscow and Tbilisi stations. It is shown that the BC decreases as the atmospheric pressure increases. Corrections to the BC are 0.0004 and 0.0013 percent/sq mb for the Moscow and Tbilisi stations, respectively.

  15. Long-term stability and zero drift of digital barometric pressure gauges

    Science.gov (United States)

    Kojima, M.; Kobata, T.; Fujii, K.

    2015-04-01

    Several digital pressure gauges at the National Metrology Institute of Japan (NMIJ) have been calibrated in the barometric pressure range on a regular basis for over ten years. The long-term stability of the zero and span readings for these pressure gauges was evaluated using their historical calibration data. The evaluation showed that most of the gauges have quite good long-term stabilities for the span readings, but some have large zero drifts with rates of about (10 to 50) Pa?yr?1. This paper discusses the causes for this drift: it can be explained by the combination of a small leak and gas emissions from the sensor volume, which are estimated from the typical drift rates. The zero drift of a particular gauge is well-approximated by an exponential function of time; the fitting function may give a good estimation of the zero drift in the future. This indicates that continuous characterization of a pressure gauge may enable appropriate correction of the indication and provide users more reliable data with less calibration work.

  16. Microblower assisted barometric valve

    Science.gov (United States)

    Rossabi, Joseph; Hyde, Warren K.; Riha, Brian D.; Jackson, Dennis G.; Sappington, Frank

    2005-12-06

    A gas exchange apparatus is provided which provides for both passive fluid flow and blower associated fluid flow through a barometric valve. A battery powered blower is provided which allows for operation of the barometric valve during times when the barometric valve would otherwise be closed, and provides for enhanced volume of gas exchange.

  17. Barometric pumping of contaminated gases through fractured permeable media

    International Nuclear Information System (INIS)

    Contaminated gases may be transported vertically through a fractured permeable medium by the breathing process which is associated with cyclical changes in the barometric pressure. A review of results from analytical and numerical modelling indicates that the contaminant transport induced by barometric pumping may be orders of magnitude greater than the rate of transport by molecular diffusion

  18. Mapping of multi-floor buildings: A barometric approach

    DEFF Research Database (Denmark)

    Özkil, Ali Gürcan; Fan, Zhun

    2011-01-01

    This paper presents a new method for mapping multi5floor buildings. The method combines laser range sensor for metric mapping and barometric pressure sensor for detecting floor transitions and map segmentation. We exploit the fact that the barometric pressure is a function of the elevation, and it varies between different floors. The method is tested with a real robot in a typical indoor environment, and the results show that physically consistent multi5floor representations are achievable.

  19. 16 CFR 1203.8 - Conditioning environments.

    Science.gov (United States)

    2010-01-01

    ...2010-01-01 2010-01-01 false Conditioning environments. 1203.8 Section...HELMETS The Standard § 1203.8 Conditioning environments. Helmets shall...13. The barometric pressure in all conditioning environments shall be 75 to...

  20. Variations in cosmic radiation intensity associated with the barometric effect

    Directory of Open Access Journals (Sweden)

    José Fco. Valdés-Galicia

    2000-05-01

    Full Text Available The barometric effect for the Mexico City neutron monitor is obtained from cosmic ray intensity data obtained during the years 1990-1997, more than half a solar cycle, by correlation between the neutron intensity and the atmospheric pressure. In order to eliminate other factors of solar or geomagnetic origin we use only geomagnetically quiet days (kp<20°. The evolution of the barometric coefficient from maximum (1990 to minimum (1997 solar activity is discussed.

  1. Barometric pumping with a twist: VOC containment and remediation without boreholes

    International Nuclear Information System (INIS)

    A large national cost is incurred in remediating near-surface contamination such as surface spills, leaking buried pipelines, and underground storage tank sites. Many of these sites can be contained and remediated using enhanced natural venting, capitalizing on barometric pumping. Barometric pumping is the cyclic movement experienced by soil gas due to oscillations in atmospheric pressure. Daily variations of 5 millibars are typical, while changes of 25 to 50 millibars can occur due to major weather front passage. The fluctuations can cause bulk vertical movement in soil gas ranging from centimeters to meters, depending on the amplitude of the pressure oscillation, soil gas permeability, and depth to an impermeable boundary such as the water table. Since the bulk gas movement is cyclic, under natural conditions no net advective vertical movement occurs over time. Science and Engineering Associates, Inc., is developing an engineered system to capitalize on the oscillatory flow for soil contaminant remediation and containment. By design, the system allows normal upward movement of soil gas but restricts the downward movement during barometric highs. The earth's surface is modified with a sealant and vent valve such that the soil gas flow is literally open-quotes ratchetedclose quotes to cause a net upward flow over time. A key feature of the design is that it does not require boreholes, resulting in a very low cost remediation effort and reduced personnel exposure risk. In the current phase (Phase I) the system's performance is being evaluated. Static and transient analysis results are presented which illustrate the relative magnitude of this advective movement compared to downward contaminant diffusion rates. Calculations also indicate the depth of influence for various surface and soil configurations. The system design will be presented, as well as a cost assessment compared to conventional techniques

  2. Barometric pumping with a twist: VOC containment and remediation without boreholes

    International Nuclear Information System (INIS)

    A large national cost is incurred in remediating near-surface contamination such as surface spills, leaking buried pipelines, and underground storage tank sites. Many of these sites can be contained and remediated using enhanced natural venting, capitalizing on barometric pumping. Barometric pumping is the cyclic movement experienced by soil gas due to oscillations in atmospheric pressure. Daily variations of 5 millibars are typical, while changes of 25 to 50 millibars can occur due to major weather front passage. The fluctuations can cause bulk vertical movement in soil gas ranging from centimeters to meters, depending on the amplitude of the pressure oscillation, soil gas permeability, and depth to an impermeable boundary such as the water table. Since the bulk gas movement is cyclic, under natural conditions no net advective vertical movement occurs over time. Science and Engineering Associates, Inc., is developing an engineered system to capitalize on the oscillatory flow for soil contaminant remediation and containment. By design, the system allows normal upward movement of soil gas but restricts the downward movement during barometric highs. The earth's surface is modified with a sealant and vent valve such that the soil gas flow is literally open-quotes ratchetedclose quotes to cause a net upward flow over time. A key feature of the design is that it does not require boreholes, resulting in a very low cost remediation effort and reduced personnel exposure risk.ffort and reduced personnel exposure risk. In the current phase (Phase I) the system's performance is being evaluated. Static and transient analysis results are presented which illustrate the relative magnitude of this advective movement compared to downward contaminant diffusion rates. Calculations also indicate the depth of influence for various surface and soil configurations. The system design will be presented, as well as a cost assessment compared to conventional techniques

  3. Barometric pumping with a twist: VOC containment and remediation without boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, W.; Dunn, S.D.; Walsh, R. [Science and Engineering Associates, Inc., Santa Fe, NM (United States)] [and others

    1995-10-01

    A large national cost is incurred in remediating near-surface contamination such as surface spills, leaking buried pipelines, and underground storage tank sites. Many of these sites can be contained and remediated using enhanced natural venting, capitalizing on barometric pumping. Barometric pumping is the cyclic movement experienced by soil gas due to oscillations in atmospheric pressure. Daily variations of 5 millibars are typical, while changes of 25 to 50 millibars can occur due to major weather front passage. The fluctuations can cause bulk vertical movement in soil gas ranging from centimeters to meters, depending on the amplitude of the pressure oscillation, soil gas permeability, and depth to an impermeable boundary such as the water table. Since the bulk gas movement is cyclic, under natural conditions no net advective vertical movement occurs over time. Science and Engineering Associates, Inc., is developing an engineered system to capitalize on the oscillatory flow for soil contaminant remediation and containment. By design, the system allows normal upward movement of soil gas but restricts the downward movement during barometric highs. The earth`s surface is modified with a sealant and vent valve such that the soil gas flow is literally {open_quotes}ratcheted{close_quotes} to cause a net upward flow over time. A key feature of the design is that it does not require boreholes, resulting in a very low cost remediation effort and reduced personnel exposure risk. In the current phase (Phase I) the system`s performance is being evaluated. Static and transient analysis results are presented which illustrate the relative magnitude of this advective movement compared to downward contaminant diffusion rates. Calculations also indicate the depth of influence for various surface and soil configurations. The system design will be presented, as well as a cost assessment compared to conventional techniques.

  4. Barometric fluctuations in wells tapping deep unconfined aquifers.

    Science.gov (United States)

    Weeks, E.P.

    1979-01-01

    Barometric effects on water levels in unconfined aquifers can be computed by solution of the differential equation governing the flow of gas in the unsaturated zone subject to the appropriate boundary conditions. Solutions to this equation for two sets of boundary conditions were applied to compute water level response in a well tapping the Ogallala Formation near Lubbock, Texas from simultaneous microbarograph records. -from Author

  5. Passive remediation of chlorinated volatile organic compounds using barometric pumping

    International Nuclear Information System (INIS)

    The purpose of the Savannah River Integrated Demonstration Program, sponsored by the Department of Energy, is to demonstrate new subsurface characterization, monitoring, and remediation technologies. The interbedded clay and sand layers at the Integrated Demonstration Site (IDS) are contaminated with chlorinated volatile organic compounds (CVOCs). Characterization studies show that the bulk of the contamination is located in the approximately 40 m thick vadose zone. The most successful strategy for removing contaminants of this type from this environment is vapor extraction alone or in combination with other methods such as air sparging or enhanced bioremediation. Preliminary work at the IDS has indicated that natural pressure differences between surface and subsurface air caused by surface barometric fluctuations can produce enough gas flow to make barometric pumping a viable method for subsurface remediation. Air flow and pressure were measured in wells that are across three stratigraphic intervals in the vadose zone' The subsurface pressures were correlated to surface pressure fluctuations but were damped and lagging in phase corresponding to depth and stratum permeability. Piezometer wells screened at lower elevations exhibited a greater phase lag and damping than wells screened at higher elevations where the pressure wave from barometric fluctuations passes through a smaller number of low permeable layers. The phase lag between surface and subsurface pressures results in significant fluxes through these wells. The resultant air flows through the subsurface impacts CVOC fate and transport. With the appropriate controls (e.g. solenoid valves) a naturally driven vapor extraction system can be implemented requiring negligible operating costs yet capable of a large CVOC removal rate (as much as 1--2 kg/day in each well at the IDS)

  6. Determination of Barometric Altimeter Errors for the Orion Exploration Flight Test-1 Entry

    Science.gov (United States)

    Brown, Denise L.; Bunoz, Jean-Philippe; Gay, Robert

    2012-01-01

    The Exploration Flight Test 1 (EFT-1) mission is the unmanned flight test for the upcoming Multi-Purpose Crew Vehicle (MPCV). During entry, the EFT-1 vehicle will trigger several Landing and Recovery System (LRS) events, such as parachute deployment, based on on-board altitude information. The primary altitude source is the filtered navigation solution updated with GPS measurement data. The vehicle also has three barometric altimeters that will be used to measure atmospheric pressure during entry. In the event that GPS data is not available during entry, the altitude derived from the barometric altimeter pressure will be used to trigger chute deployment for the drogues and main parachutes. Therefore it is important to understand the impact of error sources on the pressure measured by the barometric altimeters and on the altitude derived from that pressure. The error sources for the barometric altimeters are not independent, and many error sources result in bias in a specific direction. Therefore conventional error budget methods could not be applied. Instead, high fidelity Monte-Carlo simulation was performed and error bounds were determined based on the results of this analysis. Aerodynamic errors were the largest single contributor to the error budget for the barometric altimeters. The large errors drove a change to the altitude trigger setpoint for FBC jettison deploy.

  7. Barometric Pumping of a Fractured Porous Medium

    Science.gov (United States)

    Adler, P. M.; Mourzenko, V.; Thovert, J. F.; Pili, E.; Guillon, S.

    2014-12-01

    Fluctuations in the ambient atmospheric pressure result in motion of air in porous fractured media. This mechanism, known as barometric pumping, efficiently transports gaseous species through the vadose zone to the atmosphere. This is of interest in fields, such as transport of trace gases from soil to atmosphere, remediation of contaminated sites, radon in buildings, leakage from carbon sequestration sites and detection of nuclear explosions. The fractures are modeled as polygonal plane surfaces with a given transmissivity embedded in a permeable matrix. The slightly compressible fluid obeys Darcy's law in these two media with exchanges between them. The solute obeys convection-diffusion equations in both media again with exchanges. The fractures and the porous medium are meshed by triangles and tetrahedra, respectively. The equations are discretized by the finite volume method. A Flux Limiting Scheme diminishes numerical dispersion ; the solute transfer between the fractures and the porous medium is precisely evaluated. The resulting equations are solved by conjugate gradient algorithms. This model is applied to the Roselend Natural Laboratory. At a 55 m depth, a sealed cavity allows for gas release experiments across fractured porous rocks in the unsaturated zone. The fractures are hexagons with a radius of 5m; their density is larger than 2.4 10-3 m-3; the aperture is about 0.5 mm. The pressure fluctuations are sinusoidal, of amplitude 0.01 bar and period 1 week. The solute concentration is equal to 1 at the bottom. Systematic results will be presented. First, the precision of the calculations is assessed. Second, the pressure and solute concentration fields are displayed and discussed. Third, the influence of the major parameters (fracture density, aperture, porosity, diffusion coefficient,…) is illustrated and discussed. These results are discussed in terms of the amplification of solute transfer to the ground surface by the pressure fluctuations.

  8. A Graphical Method for Estimation of Barometric Efficiency from Continuous Data - Concepts and Application to a Site in the Piedmont, Air Force Plant 6, Marietta, Georgia

    Science.gov (United States)

    Gonthier, Gerard J.

    2007-01-01

    A graphical method that uses continuous water-level and barometric-pressure data was developed to estimate barometric efficiency. A plot of nearly continuous water level (on the y-axis), as a function of nearly continuous barometric pressure (on the x-axis), will plot as a line curved into a series of connected elliptical loops. Each loop represents a barometric-pressure fluctuation. The negative of the slope of the major axis of an elliptical loop will be the ratio of water-level change to barometric-pressure change, which is the sum of the barometric efficiency plus the error. The negative of the slope of the preferred orientation of many elliptical loops is an estimate of the barometric efficiency. The slope of the preferred orientation of many elliptical loops is approximately the median of the slopes of the major axes of the elliptical loops. If water-level change that is not caused by barometric-pressure change does not correlate with barometric-pressure change, the probability that the error will be greater than zero will be the same as the probability that it will be less than zero. As a result, the negative of the median of the slopes for many loops will be close to the barometric efficiency. The graphical method provided a rapid assessment of whether a well was affected by barometric-pressure change and also provided a rapid estimate of barometric efficiency. The graphical method was used to assess which wells at Air Force Plant 6, Marietta, Georgia, had water levels affected by barometric-pressure changes during a 2003 constant-discharge aquifer test. The graphical method was also used to estimate barometric efficiency. Barometric-efficiency estimates from the graphical method were compared to those of four other methods: average of ratios, median of ratios, Clark, and slope. The two methods (the graphical and median-of-ratios methods) that used the median values of water-level change divided by barometric-pressure change appeared to be most resistant to error caused by barometric-pressure-independent water-level change. The graphical method was particularly resistant to large amounts of barometric-pressure-independent water-level change, having an average and standard deviation of error for control wells that was less than one-quarter that of the other four methods. When using the graphical method, it is advisable that more than one person select the slope or that the same person fits the same data several times to minimize the effect of subjectivity. Also, a long study period should be used (at least 60 days) to ensure that loops affected by large amounts of barometric-pressure-independent water-level change do not significantly contribute to error in the barometric-efficiency estimate.

  9. Field measurements of tracer gas transport by barometric pumping

    International Nuclear Information System (INIS)

    Vertical gas motions induced by barometric pressure variations can carry radioactive gases out of the rubblized region produced by an underground nuclear explosion, through overburden rock, into the atmosphere. To better quantify transit time and amount of transport, field experiments were conducted at two sites on Pahute Mesa, Kapelli and Tierra, where radioactive gases had been earlier detected in surface cracks. At each site, two tracer gases were injected into the rubblized chimney 300-400 m beneath the surface and their arrival was monitored by concentration measurements in gas samples extracted from shallow collection holes. The first ''active'' tracer was driven by a large quantity of injected air; the second ''passive'' tracer was introduced with minimal gas drive to observe the natural transport by barometric pumping. Kapelli was injected in the fall of 1990, followed by Tierra in the fall of 1991. Data was collected at both sites through the summer of 1993. At both sites, no surface arrival of tracer was observed during the active phase of the experiment despite the injection of several million cubic feet of air, suggesting that cavity pressurization is likely to induce horizontal transport along high permeability layers rather than vertical transport to the surface. In contrast, the vertical pressure gradients associated with barometric pumping brought both tracers to the surface in comparable concentrations within three months at Kapelli, whereas 15 months elapsed before surface arrival at Tierra. At Kapelli, a quasisteady pumping regime was established, with tracer concentrations in effluent gases 1000 times smaller than concentrations thought to exist in the chimney. Tracer concentrations observed at Tierra were typically an order of magnitude smaller. Comparisons with theoretical calculations suggest that the gases are traveling through ?1 millimeter vertical fractures spaced 2 to 4 meters apart. 6 refs., 18 figs., 3 tabs

  10. Barometric pumping of a fractured porous medium

    Science.gov (United States)

    Adler, Pierre; Varloteaux, Clément; Mourzenko, Valeri; François Thovert, Jean; Guillon, Sophie; Pili, Eric

    2014-05-01

    Fluctuations in the ambient atmospheric pressure result in motion of air in porous and fractured media. This mechanism, known as barometric (or atmospheric) pumping, efficiently transports gaseous species through the vadose zone to the atmosphere. This is of interest in many environmental and engineering fields, such as transport of trace gases from soil to atmosphere, environmental remediation of contaminated sites, radon in buildings and last but not least detection of nuclear explosions or leakage from carbon sequestration sites. The physical situation has been addressed in the following way. The fractures are modeled as polygonal plane surfaces with a given transmissivity embedded in a porous medium with a given permeability. The fluid is slightly compressible and is assumed to obey Darcy's law in the fractures and the porous medium with exchanges between them. The solute obeys convection-diffusion equations in both media again with exchanges between them. The fractures and the porous medium located in between them are meshed by triangles and tetrahedra. The equations are discretized by the finite volume method. In order to improve numerical precision, a Flux Limiting Scheme is applied to the transport equations ; moreover, special care is devoted to the description of the solute transfer between the fractures and the porous medium. The resulting equations are solved by conjugate gradient algorithms. This model is applied to the Roselend Natural Laboratory. At a 55 m depth, a sealed cavity allows for gas release experiments across fractured porous rocks in the unsaturated zone. The fractures are hexagons with a radius of 5m; their density is larger than 2.4 10-3 m-3; the aperture is of the order of 0.5 mm. The pressure fluctuations are sinusoidal, of amplitude 0.01 bar and period 1 week. The solute concentration is supposed to be equal to 1 at the bottom of the site. Systematic results will be presented. First, the precision of the calculations is assessed. Second, the pressure fluctuations and the solute concentration in the fractured porous medium is displayed and discussed. Third, the influence of the major parameters (fracture density and aperture, porosity, diffusion coefficient,…) is illustrated and discussed. These results are discussed in terms of the amplification of solute transfer to the ground surface by the pressure fluctuations. Finally, it should be emphasized that the codes can be easily modified to address time dependent thermal transfers in fractured porous media.

  11. An Educational Study of the Barometric Effect of Cosmic Rays with a Geiger Counter

    Science.gov (United States)

    Famoso, Barbara; La Rocca, Paola; Riggi, Francesco

    2005-01-01

    An educational study of the barometric effect of cosmic rays was carried out using an inexpensive experimental set-up that allowed for long-term monitoring of atmospheric pressure and cosmic ray flux as measured in a Geiger counter. The investigation was intended as a pilot study in view of ongoing involvements of high-school teams operating…

  12. Observando as marés atmosféricas: uma aplicação da placa Arduino com sensores de pressão barométrica e temperatura / Observing the atmospheric tides: an application of the Arduino board with sensors for barometric pressure and temperature

    Scientific Electronic Library Online (English)

    Luiz Raimundo Moreira de, Carvalho; Helio Salim de, Amorim.

    2014-09-01

    Full Text Available Apresentamos uma montagem experimental simples para o estudo da maré atmosférica, baseada no uso da placa Arduino Uno. Com essa montagem, o professor de física no Ensino Médio poderá apresentar para seus alunos as oscilações barométricas, um efeito fundamentalmente de origem térmica devido ao aqueci [...] mento da atmosfera produzido pela radiação solar. Apresentamos também uma comparação entre a maré atmosférica e o efeito gravitacional da maré oceânica, destacando as diferenças entre os dois fenômenos. Abstract in english We present a simple experimental apparatus for studying the atmospheric tide based on the use of Arduino Uno board. With this apparatus, the physics teacher in high school can present to your students barometric oscillations, an effect mainly of thermal origin, due to the warming of the atmosphere p [...] roduced by solar radiation. We also present a comparison between atmospheric tide and the gravitational effect of ocean tide, with emphasis on the differences between the two phenomena.

  13. Spray combustion under oscillatory pressure conditions

    Science.gov (United States)

    Jacobs, H. R.; Santoro, R. J.

    1991-01-01

    The performance and stability of liquid rocket engines is often argued to be significantly impacted by atomization and droplet vaporization processes. In particular, combustion instability phenomena may result from the interactions between the oscillating pressure field present in the rocket combustor and the fuel and oxidizer injection process. Few studies have been conducted to examine the effects of oscillating pressure fields on spray formation and its evolution under rocket engine conditions. The pressure study is intended to address the need for such studies. In particular, two potentially important phenomena are addressed in the present effort. The first involves the enhancement of the atomization process for a liquid jet subjected to an oscillating pressure field of known frequency and amplitude. The objective of this part of the study is to examine the coupling between the pressure field and or the resulting periodically perturbed velocity field on the breakup of the liquid jet. In particular, transverse mode oscillations are of interest since such modes are considered of primary importance in combustion instability phenomena. The second aspect of the project involves the effects of an oscillating pressure on droplet coagulation and secondary atomization. The objective of this study is to examine the conditions under which phenomena following the atomization process are affected by perturbations to the pressure or velocity fields. Both coagulation and represent a coupling mechanism between the pressure field and the energy release process in rocket combustors. It is precisely this coupling which drives combustion instability phenomena. Consequently, the present effort is intended to provide the fundamental insights needed to evaluate these processes as important mechanisms in liquid rocket instability phenomena.

  14. Effects of weather and heliophysical conditions on emergency ambulance calls for elevated arterial blood pressure.

    Science.gov (United States)

    Vencloviene, Jone; Babarskiene, Ruta M; Dobozinskas, Paulius; Sakalyte, Gintare; Lopatiene, Kristina; Mikelionis, Nerijus

    2015-03-01

    We hypothesized that weather and space weather conditions were associated with the exacerbation of essential hypertension. The study was conducted during 2009-2010 in the city of Kaunas, Lithuania. We analyzed 13,475 cards from emergency ambulance calls (EACs), in which the conditions for the emergency calls were made coded I.10-I.15. The Kaunas Weather Station provided daily records of air temperature (T), wind speed (WS), relative humidity, and barometric pressure (BP). We evaluated the associations between daily weather variables and daily number of EACs by applying a multivariate Poisson regression. Unfavorable heliophysical conditions (two days after the active-stormy geomagnetic field or the days with solar WS>600 km/s) increased the daily number of elevated arterial blood pressure (EABP) by 12% (RR=1.12; 95% confidence interval (CI) 1.04-1.21); and WS?3.5 knots during days of T<1.5 °C and T?12.5 °C by 8% (RR=1.08; CI 1.04-1.12). An increase of T by 10 °C and an elevation of BP two days after by 10 hPa were associated with a decrease in RR by 3%. An additional effect of T was detected during days of T?17.5 °C only in females. Women and patients with grade III arterial hypertension at the time of the ambulance call were more sensitive to weather conditions. These results may help in the understanding of the population's sensitivity to different weather conditions. PMID:25734792

  15. Effects of Weather and Heliophysical Conditions on Emergency Ambulance Calls for Elevated Arterial Blood Pressure

    Directory of Open Access Journals (Sweden)

    Jone Vencloviene

    2015-02-01

    Full Text Available We hypothesized that weather and space weather conditions were associated with the exacerbation of essential hypertension. The study was conducted during 2009–2010 in the city of Kaunas, Lithuania. We analyzed 13,475 cards from emergency ambulance calls (EACs, in which the conditions for the emergency calls were made coded I.10–I.15. The Kaunas Weather Station provided daily records of air temperature (T, wind speed (WS, relative humidity, and barometric pressure (BP. We evaluated the associations between daily weather variables and daily number of EACs by applying a multivariate Poisson regression. Unfavorable heliophysical conditions (two days after the active-stormy geomagnetic field or the days with solar WS > 600 km/s increased the daily number of elevated arterial blood pressure (EABP by 12% (RR = 1.12; 95% confidence interval (CI 1.04–1.21; and WS ? 3.5 knots during days of T < 1.5 °C and T ? 12.5 °C by 8% (RR = 1.08; CI 1.04–1.12. An increase of T by 10 °C and an elevation of BP two days after by 10 hPa were associated with a decrease in RR by 3%. An additional effect of T was detected during days of T ? 17.5 °C only in females. Women and patients with grade III arterial hypertension at the time of the ambulance call were more sensitive to weather conditions. These results may help in the understanding of the population’s sensitivity to different weather conditions.

  16. Using Multiple Barometers to Detect the Floor Location of Smart Phones with Built-in Barometric Sensors for Indoor Positioning.

    Science.gov (United States)

    Xia, Hao; Wang, Xiaogang; Qiao, Yanyou; Jian, Jun; Chang, Yuanfei

    2015-01-01

    Following the popularity of smart phones and the development of mobile Internet, the demands for accurate indoor positioning have grown rapidly in recent years. Previous indoor positioning methods focused on plane locations on a floor and did not provide accurate floor positioning. In this paper, we propose a method that uses multiple barometers as references for the floor positioning of smart phones with built-in barometric sensors. Some related studies used barometric formula to investigate the altitude of mobile devices and compared the altitude with the height of the floors in a building to obtain the floor number. These studies assume that the accurate height of each floor is known, which is not always the case. They also did not consider the difference in the barometric-pressure pattern at different floors, which may lead to errors in the altitude computation. Our method does not require knowledge of the accurate heights of buildings and stories. It is robust and less sensitive to factors such as temperature and humidity and considers the difference in the barometric-pressure change trends at different floors. We performed a series of experiments to validate the effectiveness of this method. The results are encouraging. PMID:25835189

  17. Using Multiple Barometers to Detect the Floor Location of Smart Phones with Built-in Barometric Sensors for Indoor Positioning

    Science.gov (United States)

    Xia, Hao; Wang, Xiaogang; Qiao, Yanyou; Jian, Jun; Chang, Yuanfei

    2015-01-01

    Following the popularity of smart phones and the development of mobile Internet, the demands for accurate indoor positioning have grown rapidly in recent years. Previous indoor positioning methods focused on plane locations on a floor and did not provide accurate floor positioning. In this paper, we propose a method that uses multiple barometers as references for the floor positioning of smart phones with built-in barometric sensors. Some related studies used barometric formula to investigate the altitude of mobile devices and compared the altitude with the height of the floors in a building to obtain the floor number. These studies assume that the accurate height of each floor is known, which is not always the case. They also did not consider the difference in the barometric-pressure pattern at different floors, which may lead to errors in the altitude computation. Our method does not require knowledge of the accurate heights of buildings and stories. It is robust and less sensitive to factors such as temperature and humidity and considers the difference in the barometric-pressure change trends at different floors. We performed a series of experiments to validate the effectiveness of this method. The results are encouraging. PMID:25835189

  18. Using Multiple Barometers to Detect the Floor Location of Smart Phones with Built-in Barometric Sensors for Indoor Positioning

    Directory of Open Access Journals (Sweden)

    Hao Xia

    2015-03-01

    Full Text Available Following the popularity of smart phones and the development of mobile Internet, the demands for accurate indoor positioning have grown rapidly in recent years. Previous indoor positioning methods focused on plane locations on a floor and did not provide accurate floor positioning. In this paper, we propose a method that uses multiple barometers as references for the floor positioning of smart phones with built-in barometric sensors. Some related studies used barometric formula to investigate the altitude of mobile devices and compared the altitude with the height of the floors in a building to obtain the floor number. These studies assume that the accurate height of each floor is known, which is not always the case. They also did not consider the difference in the barometric-pressure pattern at different floors, which may lead to errors in the altitude computation. Our method does not require knowledge of the accurate heights of buildings and stories. It is robust and less sensitive to factors such as temperature and humidity and considers the difference in the barometric-pressure change trends at different floors. We performed a series of experiments to validate the effectiveness of this method. The results are encouraging.

  19. A Sensor Fusion Method for Tracking Vertical Velocity and Height Based on Inertial and Barometric Altimeter Measurements

    Directory of Open Access Journals (Sweden)

    Angelo Maria Sabatini

    2014-07-01

    Full Text Available A sensor fusion method was developed for vertical channel stabilization by fusing inertial measurements from an Inertial Measurement Unit (IMU and pressure altitude measurements from a barometric altimeter integrated in the same device (baro-IMU. An Extended Kalman Filter (EKF estimated the quaternion from the sensor frame to the navigation frame; the sensed specific force was rotated into the navigation frame and compensated for gravity, yielding the vertical linear acceleration; finally, a complementary filter driven by the vertical linear acceleration and the measured pressure altitude produced estimates of height and vertical velocity. A method was also developed to condition the measured pressure altitude using a whitening filter, which helped to remove the short-term correlation due to environment-dependent pressure changes from raw pressure altitude. The sensor fusion method was implemented to work on-line using data from a wireless baro-IMU and tested for the capability of tracking low-frequency small-amplitude vertical human-like motions that can be critical for stand-alone inertial sensor measurements. Validation tests were performed in different experimental conditions, namely no motion, free-fall motion, forced circular motion and squatting. Accurate on-line tracking of height and vertical velocity was achieved, giving confidence to the use of the sensor fusion method for tracking typical vertical human motions: velocity Root Mean Square Error (RMSE was in the range 0.04–0.24 m/s; height RMSE was in the range 5–68 cm, with statistically significant performance gains when the whitening filter was used by the sensor fusion method to track relatively high-frequency vertical motions.

  20. Sealing of rotary drums for operation under pressurized conditions

    International Nuclear Information System (INIS)

    In practice, rotary drums are always designed for operation under vacuum conditions. In this paper, a novel technique is proposed for sealing the rotary drums under pressurized conditions. The proposed system is based on applying a secondary pressurized volume around the leaking gap of the drum. By controlling the pressure of this volume above the pressure of the drum, it will be possible to prevent from any leakage of gases to the ambient. The objective of a controller in this system is that the pressure of secondary volume be kept above the pressure of the drum in spite of the disturbances which may be exerted on the system by the wind outside the drum. The control system is also required to trace the variations in the drum pressure with the least fluctuations in the pressure difference among the drum and the volume

  1. Practical conditions in the neutron diffraction under high pressure

    International Nuclear Information System (INIS)

    Practical analysis is made on some conditions in utilizing neutrons for the study of atomistic structure of materials under high pressure. Investigation is made on the geometrical conditions; size of the specimen, width of slits, and the rate of extra-scattering. Experiments are performed on the effects of absorption by high pressure cell and the disturbance due to an overlapping of diffraction peaks. An observation is presented on the pressure-induced transformation in RbBr. (author)

  2. Steam pressure spike in PWR plant under severe accident conditions

    International Nuclear Information System (INIS)

    An evaluation of the steam pressure spike due to core debris/water interaction under severe accident conditions is presented for pressurized water reactors with large dry and ice condenser containments. The MARCH computer code was modified to analyze the debris/water interaction. Comparative analyses were performed for the single-sphere model (highly dispersed debris particles) and the dryout heat flux model (packed debris bed). For a TMLB' accident in a large dry containment, the single-sphere model predicts a rapid pressure rise at vessel failure, and the debris bed model shows a much slower pressure rise. The peak containment pressure does not exceed current estimates of containment failure pressure. For the case of ice condenser plant, the deinerting effect of ice could result in simultaneous hydrogen ignitions together with the steam spike at vessel failure. The predicted pressure rise could be greater than the estimated failure pressure of the ice condenser plant

  3. Analysis of air-conditioning and drying processes using spreadsheet add-in for psychrometric data

    OpenAIRE

    Diemuodeke, E. O.; Oko, C. O. C.

    2010-01-01

    A spreadsheet add-in for the psychrometric data at any barometric pressure and in the air-conditioning and drying temperatureranges was developed using appropriate correlations. It was then used to simulate and analyse air-conditioning and dryingprocesses in the Microsoft Excel environment by exploiting its spreadsheet and graphic potentials. The package allowsone to determine the properties of humid air at any desired state, and to simulate and analyse air-conditioning as well asdrying proce...

  4. Determination of barometric efficiency and effective porosity, boreholes UE-25 cNo.1, UE-25 cNo.3, Yucca Mountain, Nye County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Geldon, A.L.; Earle, J.D.; Umari, A.M.A.

    1997-12-31

    Simultaneous records of water-level altitudes in boreholes UE-25 cNo.1, UE-25 cNo.2, and UE-25 cNo.3 (the C-holes) and atmospheric pressure at and near the C-holes were obtained from July 15 to September 8, 1993, to determine the barometric efficiency of the entire uncased section of each of the C-holes, for the purpose of analyzing pumping tests. Each of the C-holes is 3,000 feet deep. About 1,600 feet of each borehole is open in Miocene tuffaceous rocks. Water-level altitudes in the C-holes fluctuate in response to Earth tides and changes in atmospheric pressure, which are characteristics of wells completed in an elastic, confined aquifer. The barometric efficiency of the C-holes in this study was analyzed by filtering simultaneously collected water-level-altitude and atmospheric-pressure data to remove the influences of Earth tides and semi-diurnal heating and cooling and then regressing filtered water-level-altitude changes as a function of filtered changes in atmospheric pressure. The average barometric efficiency of the uncased sections of boreholes UE-25 cNo.1 and UE-25 cNo.3 was determined to be 0.94. Malfunctioning equipment prevented determining the barometric efficiency of bore-hole UE-25 cNo.2. An average effective porosity of 0.36 was calculated from barometric efficiency values determined in this study and a specific storage value of 0.497 x 10{sup -6} per foot that was determined previously from geophysical logs of the C-holes. A porosity of 0.36 is consistent with values determined from geophysical logs and core analyses for the Calico Hills Formation.

  5. On Boundary Conditions for Fluids with Pressure Dependent Viscosity.

    Czech Academy of Sciences Publication Activity Database

    Lanzendörfer, Martin; Stebel, Jan

    Ostrava : Institute of Geonics AS CR, 2009 - (Blaheta, R.; Starý, J.). s. 75-76 ISBN 978-80-86407-66-1. [Modelling 2009. IMACS Conference on Mathematical Modelling and Computational Methods in Applied Sciences and Engineering /4./. 22.06.2009-26.06.2009, Rožnov pod Radhošt?m] R&D Projects: GA ?R GA201/09/0917 Institutional research plan: CEZ:AV0Z10300504 Keywords : existence * weak solutions * incompressible fluids * non-Newtonian fluids * pressure dependent viscosity * shear dependent viscosity * inflow/outflow boundary conditions * pressure boundary conditions * filtration boundary conditions

  6. Pyrolysis and gasification behavior of black liquor under pressurized conditions

    Energy Technology Data Exchange (ETDEWEB)

    Whitty, K.

    1997-11-01

    The purpose of this study has been to enhance the understanding of the processes involved in pressurized black liquor gasification. Gasification is known to occur in three stages: drying, pyrolysis and char gasification. The work presented here focuses on the pyrolysis and gasification stages. Experiments were carried out primarily in two laboratory-scale reactors. A pressurized grid heater was used to study black liquor pyrolysis under pressurized conditions. Char yields and the fate of elements in the liquor, as well as the degree of liquor swelling, were measured in this device. A pressurized thermogravimetric reactor was used to measure the rate of the char gasification process under different temperatures and pressures and in various gas atmospheres. Pyrolysis experiments were also carried out in this device, and data on swelling behavior, char yields and component release were obtained 317 refs.

  7. Bulging of pressure tubes at hot spots under LOCA conditions

    International Nuclear Information System (INIS)

    During certain postulated loss-of-coolant accidents (LOCA) in a CANDU reactor, some fuel channels can become highly voided within a very short time. Although the pressure tubes are heated mainly by convection and thermal radiation during the LOCA transient, additional heat flow occurs through the bearing pads that are in contact with the pressure tribe. This contact can lead to local hot spots and associated thermal stresses in the pressure tube wall. The two factors that affects the behavior of the pressure tubes during LOCA conditions are the internal pressure and the local heating. Although the effect of internal pressure and of axially uniform temperature has been studied elsewhere, the effect of the local heating on the pressure tube behavior has not been modelled before. This paper shows that the bulging of a pressure tube at a hot spot is the result of the thermal stresses that are developed in a pressure tube during a LOCA transient. To isolate the local heating effect from the internal pressure, a series of single-effect experiments was performed. In these experiments, sections of a CANDU pressure tube were subjected to local heating only. The thermal profile and the local deformation were measured function of time. To quantify the effect of the thermal stresses on the bulging of pressure tubes at hot spots and to develop numerical tools that can predict such bulging, finite element analyses were performed rising the ABAQUS finite element computer code. Use oABAQUS finite element computer code. Use of the measured thermal profiles in the ABAQUS finite element analysis, resulted in very good agreement between the predicted and measured displacements. (author)

  8. A Stochastic Approach to Noise Modeling for Barometric Altimeters

    Directory of Open Access Journals (Sweden)

    Angelo Maria Sabatini

    2013-11-01

    Full Text Available The question whether barometric altimeters can be applied to accurately track human motions is still debated, since their measurement performance are rather poor due to either coarse resolution or drifting behavior problems. As a step toward accurate short-time tracking of changes in height (up to few minutes, we develop a stochastic model that attempts to capture some statistical properties of the barometric altimeter noise. The barometric altimeter noise is decomposed in three components with different physical origin and properties: a deterministic time-varying mean, mainly correlated with global environment changes, and a first-order Gauss-Markov (GM random process, mainly accounting for short-term, local environment changes, the effects of which are prominent, respectively, for long-time and short-time motion tracking; an uncorrelated random process, mainly due to wideband electronic noise, including quantization noise. Autoregressive-moving average (ARMA system identification techniques are used to capture the correlation structure of the piecewise stationary GM component, and to estimate its standard deviation, together with the standard deviation of the uncorrelated component. M-point moving average filters used alone or in combination with whitening filters learnt from ARMA model parameters are further tested in few dynamic motion experiments and discussed for their capability of short-time tracking small-amplitude, low-frequency motions.

  9. Barometric tides from ECMWF operational analyses

    Directory of Open Access Journals (Sweden)

    R. D. Ray

    Full Text Available The solar diurnal and semidiurnal tidal oscillations in surface pressure are extracted from the operational analysis product of the European Centre for Medium Range Weather Forecasting (ECMWF. For the semidiurnal tide this involves a special temporal interpolation, following Van den Dool et al. (1997. The resulting tides are compared with a "ground truth" tide data set, a compilation of well-determined tide estimates deduced from many long time series of station barometer measurements. These comparisons show that the ECMWF (analysis tides are significantly more accurate than the tides deduced from two other widely available reanalysis products. Spectral analysis of ECMWF pressure series shows that the tides consist of sharp central peaks with modulating sidelines at integer multiples of 1 cycle/year, superimposed on a broad cusp of stochastic energy. The integrated energy in the cusp dominates that of the side-lines. This complicates the development of a simple empirical model that can characterize the full temporal variability of the tides.

    Key words. Meteorology and atmospheric dynamics (waves and tides

  10. Pohorje eclogites revisited: Evidence for ultrahigh-pressure metamorphic conditions

    Directory of Open Access Journals (Sweden)

    Mirijam Vrabec

    2010-06-01

    Full Text Available Kyanite eclogites from the Pohorje Mountains, Slovenia, are providing the first evidence of ultrahigh-pressureEo-Alpine metamorphism in the Eastern Alps. Polycrystalline quartz inclusions in garnet, omphacite and kyaniteare surrounded by radial fractures and exhibit microtextures diagnostic for the recovery after coesite breakdown.The non-stoichiometric supersilicic omphacites found in Pohorje eclogites contain up to 5 mol % of Ca-Eskola molecule.Such clinopyroxenes are known to be stable exclusively at high-pressure conditions exceeding 3 GPa. Theirbreakdown during decompression resulted in exolution of quartz rods and needles that are oriented parallel toomphacite c-axis. The absence of coesite is a consequence of near-isothermal decompression during the first stagesof exhumation.Pressure and temperature conditions for the formation of the peak metamorphic mineral assemblages have beenassessed through a consideration of a Fe2+-Mg partitioning between garnet and omphacite pairs, based on differentcalibrations; b the equilibrium between garnet + clinopyroxene + phengite ? kyanite ± quartz/coesite assemblage.Estimated peak pressure and temperature conditions of 3.0-3.1 GPa and 750-783 °C are well within the coesite, i.e.the ultrahigh-pressure stability field.

  11. Oxide ceramics under extreme pressure and radiation conditions

    International Nuclear Information System (INIS)

    This experimental study tackles the question how oxide ceramics (ZrO2 and HfO2) respond to the simultaneous exposure to two extreme conditions, pressures up to several ten GPa and irradiation with highly energetic (MeV-GeV) heavy ion projectiles. The combination of these two extreme conditions influences the materials in ways none of those two conditions alone could. In both materials, the exposure to high-fluence irradiations at ambient pressure result in a crystalline-to-crystalline phase transformation from the monoclinic into the first high temperature tetragonal phase. For heavy ions such as Xe, Au, Pb, and U this structural change requires a double impact process. For light ions such as Ni and Cr, the transferred energy does not suffice to induce any transformation indicating an energy loss threshold in ZrO2 as well as in HfO2. If the irradiation is performed under high pressure, the monoclinic-to-tetragonal transformation occurs already at a fluence that is more than one order of magnitude lower, suggesting a single-hit process. Although the ZrO2 and HfO2 behave much alike as no two other compound materials, their response to the combination of pressure and ion irradiation differs. X-ray diffraction analysis of the irradiated, pressurized samples and Raman and TEM measurements at ambient conditions revealed that the monoclinic-to-tetragonal transformation in ZrO2 around 10 GPa is not direct but includes a detour into the cubic high-temperature phase, before the tetragonal structure becomes stable under decompression. For HfO2, high fluence irradiation at 10 GPa results in the intensification of the first high pressure phase which is afterwards stabilized to ambient conditions. At higher pressures, additional ion irradiation forces both ceramics to perform a transition into their second high pressure phase (orthorhombic-II) far away from its stability field. This study demonstrates that the combination of ion irradiation and high pressure can serve as a trigger for transitions into different phases and as stabilization mechanism of usually unstable structures.

  12. Investigations on pressure suppression system loads at accident conditions

    International Nuclear Information System (INIS)

    For simulation of the integral behavior of pressure suppresion systems at accident conditions a mathematical model was developed which simulates a wide range of the loads occurring during a loss-of coolant accident. The multi-zone point model DRASYS serves for mathematical simulation of quasistatic (pressure and temperature build-up in the dry well and the suppression chamber) as well as dynamic loads (free-blowing process, water throw-up and condensing oscillations) in the course of a loss-of-coolant accident. For determination of the state variations with time in the individual pressure sections thermodynamic equilibrium is assumed between steam and water phases. Thermal non-equilibrium states are taken into account if phase separation interfaces between water and steam/air mixture exist. The flows between the individual pressure sections are treated as homogeneous, nonsteady, incompressible flows. For verification of the mathematical model recalculations were made of experiments performed at various test stands. Teh recalculations showed that the mathematical model has got a wide range of application and is suited for design and assessment of pressure suppression systems at accident conditions. (orig.)

  13. Drying kinetics of RDX under atmospheric pressure and vacuum conditions

    International Nuclear Information System (INIS)

    Highlights: • In this study, RDX is dried in the ranges of 60–90 °C under atmospheric pressure and vacuum conditions. • Ten models are used to describe the drying of RDX. • The Midilli–Kucuk model is determined as the most suitable model. • Effective moisture diffusivity and activation energy for drying process are determined. - Abstract: The drying characteristics of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are investigated in the ranges of 60–90 °C of drying temperature under atmospheric pressure and vacuum conditions in a laboratory scale dryer. The effect of drying temperature and absolute pressure on the drying characteristics is determined. In order to estimate and select the suitable form of RDX drying curves, the curves are fitted to ten different semi-theoretical and/or empirical thin-layer drying models and coefficients are evaluated by non-linear regression analysis. The models are compared based on their coefficient of determination, such as mean bias error, root mean square error, reduced chi-square and modeling efficiency between experimental and predicted moisture ratios. It is deduced that Midilli–Kucuk model has shown a better fit to the experimental drying data as compared to other models. A diffusion model is used to describe the moisture transfer and the effective diffusivity for RDX drying is also determined at each temperature. Beside, the activation energy is also expressed using Arrhenius-type relationship under atmospheric pressure and vacuum conditions

  14. Touch mode micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Eriksen, Gert F.

    2010-01-01

    In the last decades, pressure sensors have been one of the greatest successes of the MEMS industry. Many companies are using them in a variety of applications from the automotive to the environmental field. Currently piezoresistive pressure sensors are the most developed, and a well established technology to design and fabricate these sensors has been implemented. Capacitive pressure sensing, on the other hand, is still an open and really promising field. Results Capacitive microsensors were designed and fabricated (Fig. 1) and an analytical model for touch mode regime, which fitted accurately the measurements done on the devices, was investigated. Fabrication was carried on at Danchip cleanrooms where fusion bonding was used in order to obtain a thin silicon plate on top of a sealed vacuum cavity (Fig. 2). A viable signal conditioning scheme for capacitive pressure sensing was simulated and implemented. A measurement setup was arranged and tested for accuracy and reliability with respect to hysteresis. Finally, designs with different radii of the top plate were characterized by a capacitance versus pressure curve at different frequencies and temperatures (Fig. 3). Industrial possibilities Energy saving systems is one of the key challenges nowadays. In this context, house heating is a priority for environmental issues. For this reason, the possibilities of using a low power consumption technique, such as capacitive pressure sensing, in harsh environments is a concrete market opportunity. Our aim is therefore to develop new technologies based on capacitive sensing to be able to fulfil future requirements in this field.

  15. Void fraction distribution in rod bundle under high pressure conditions

    International Nuclear Information System (INIS)

    This paper reports on a series of experiments that were performed at the ROSA-IV Large Scale Test Facility (LSTF) to measure the void fraction distribution in the simulated reactor core rod bundle under high-pressure low-flow conditions. The LSTF is a scaled model of a Westinghouse-type PWR containing a full-length, 1104-rod electrically heated bundle. The tests were conducted at pressures between 1.0 and 17.2 MPa, for the average heat fluxes from 4.5 to 62 kW/m2. The Cunningham-Yeh and Chexal-Lellouche void fraction correlations were assessed against the LSTF results. Moreover, a new correlation applicable to a wide range of pressure and heat flux was developed on the basis of the experimental data

  16. A NEW METHOD FOR PRESSURE SENSOR EQUILLIBRATION AND CONDITIONING

    Directory of Open Access Journals (Sweden)

    George Papaioannou

    2008-09-01

    Full Text Available PAPAIOANNOU, G.; PROTOPAPPAS, V.C.; TSOPELAS, P.; MITROGIANNIS, C.; NIANIOS, G.; TASHMAN, S. A New Method for Pressure Sensor Equillibration and Conditioning. Brazilian Journal of Biomotricity, v. 2, n. 3, p. 176-195, 2008. Assessing pressure and contact stress distributions between two adjacent surfaces is a well established research area in biomechanics. Typical applications of measuring the interface pressure include human-machine interfaces in ergonomics, joint congruency studies in orthopaedics, in-vitro cadaveric experimentation and the design of Orthotic-Prosthetic devices. Tekscan pressure sensors are widely used in both in-vivo and in-vitro experiments. An all-round efficient equilibration and calibration approach of the Tekscan sensor system is yet to be clearly defined in the literature and is attempted here for one type of Tekscan sensors. The response of individual sensels from two 5315 Tekscan sensors for quasi-static, repeated constant and dynamic loading was investigated with the use of two methods, namely the “Bladder Method” and the “Pin Method”. In the first method, uniform pressure was applied by a bladder-equilibrator, whereas in the second loads were applied in a sensel-by-sensel approach by means of a pin attached to a frame installed on a material testing machine. The “Pin Method”, although far more laborious, is a better method for equilibration and calibration of sensors, particularly when saturation is prevalent. The pin-method also provides a better characterization of the sensor drift. It was shown that when test conditions resulted in some of the sensels being saturating due to high pressure, the loss of load data from the sensor mat could be estimated using the individual sensel output.

  17. A multigrid fluid pressure solver handling separating solid boundary conditions.

    Science.gov (United States)

    Chentanez, Nuttapong; Müller-Fischer, Matthias

    2012-08-01

    We present a multigrid method for solving the linear complementarity problem (LCP) resulting from discretizing the Poisson equation subject to separating solid boundary conditions in an Eulerian liquid simulation’s pressure projection step. The method requires only a few small changes to a multigrid solver for linear systems. Our generalized solver is fast enough to handle 3D liquid simulations with separating boundary conditions in practical domain sizes. Previous methods could only handle relatively small 2D domains in reasonable time, because they used expensive quadratic programming (QP) solvers. We demonstrate our technique in several practical scenarios, including nonaxis-aligned containers and moving solids in which the omission of separating boundary conditions results in disturbing artifacts of liquid sticking to solids. Our measurements show, that the convergence rate of our LCP solver is close to that of a standard multigrid solver. PMID:22411885

  18. Continuous positive airway pressure setups evaluated at simulated exercise conditions

    Scientific Electronic Library Online (English)

    Marcelo Vieira Leão, Nunes; Antonio, Giannella-Neto; Frederico Caetano Jandre de Assis, Tavares.

    2014-06-01

    Full Text Available INTRODUCTION: Studies have shown increases in airway opening pressure (Pao) swings and work of breathing (WOB) by different continuous positive airway pressure (CPAP) devices at rest, but few address this issue during exercise. The aim of the present work was to analyze the imposed WOB (WOBi), the a [...] pparent resistance (Rapp) and swings of Pao (deltaP) of 3 CPAP assemblies at simulated exercise conditions. METHODS: The CPAP measures were obtained from: a commercial CPAP (Assembly 1), a high flow CPAP (Assembly 2) and the parallel association of these devices (Assembly 3). In each assembly the spring-loaded positive end-expiratory pressure (PEEP) valve was set to fully opened (mode A) or at the same CPAP pressure (mode B). The exercise protocol simulation, performed manually by a calibrated syringe and a metronome, employed a respiratory frequency of 30 bpm, tidal volume of 2.7 L and inspiratory-to-expiratory ratio of 1. The setups were evaluated at CPAP settings of 5, 10 and 15 cmH2O. RESULTS: The lowest deltaP as well as Rapp and WOBi were obtained with Assembly 3 in mode A with an adjusted CPAP of 10 cmH2O (deltaP=8.1 (0.5) cmH2O, WOBi=1.4 (0.14) cmH2O/L/s, Rapp= 1.3 (0.07) J/s) showed as median (interquartile range). CONCLUSION: For the conditions studied, the best CPAP setup was obtained with mode A.

  19. Pressurized thermal shock. Thermo-hydraulic conditions in the CNA-I reactor pressure vessel

    International Nuclear Information System (INIS)

    In this paper we analyze several reports issued by the Utility (Nucleo Electrica S.A.) and related to Reactor Pressure Vessel (RPV) phenomena in the CNA-I Nuclear Power Plant. These analyses are aimed at obtaining conclusions and establishing criteria ensuring the RPV integrity. Special attention was given to the effects ECCS cold-water injection at the RPV down-comer leading to pressurized thermal shock scenarios. The results deal with hypothetical primary system pipe breaks of different sizes, the inadvertent opening of the pressurizer safety valve, the double guillotine break of a live steam line in the containment and the inadvertent actuation pressurizer heaters. Modeling conditions were setup to represent experiments performed at the UPTF, under the hypothesis that they are representative of those that, hypothetically, may occur at the CNA-I. No system scaling analysis was performed, so this assertion and the inferred conclusions are no fully justified, at least in principle. The above mentioned studies, indicate that the RPV internal wall surface temperature will be nearly 40 degree. It was concluded that they allowed a better approximation of PTS phenomena in the RPV of the CNA-I. Special emphasis was made on the influence of the ECCS systems on the attained RPV wall temperature, particularly the low-pressure TJ water injection system. Some conservative hypothesis made, are discussed in this report. (author)

  20. Micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio

    2012-01-01

    Micromachined capacitive pressure sensors for harsh environment together with interfacing electronic circuits have been studied in this project. Micro-electromechanical systems (MEMS) have been proposed as substitutes for macro scale sensor’s systems in many different fields and are the only possible solution in many cases where, for example, the dimensions of the sensing element is the limiting factor. Furthermore, MEMS can significantly reduce costs and power consumption being the best candidate for consumer electronics such as mobile phones and cameras, or for the automotive industry where a great deal of sensors are used. Pressure sensors are among the most successful MEMS and are used in a huge variety of applications. In this project an absolute capacitive pressure sensor has been developed with the aim to integrate it in pump control systems to improve the efficiency of the pump. The developed MEMS consist of hermetically sealed vacuum cavities surrounded by two heavily doped silicon layers which constitute the plates of a capacitor. The top plate is also the sensing element being a thin diaphragm that deflects when pressure is applied, thus increasing the capacitance (i.e. the output signal) of the device. Fusion bonding of two wafers has been used in order to obtain the cavities, this is also the only non-standard cleanroom process involved in the fabrication of the transducers. The device developed can measure absolute pressures from 0 to 10 bar with sensitivity up to 80 pF/bar. As a part of the project a suitable interfacing circuit has been developed. Different solutions have been studied in order to optimize size, costs, sensitivity and stability. A comparative analysis between them has been carried out and suggestion for the final product has been proposed. Both the electronic conditioning circuits and the MEMS have been fully described with mathematical models and simulated with electrical networks software for the circuit part and finite element for the sensor part. A good matching between analytical models and simulations results has been achieved. Furthermore, the experimental results are in good agreement with the models proposed. Finally a demonstrator has been fabricated under the constraints of a previously designed case in order to contain costs; modification or re-design of the packaging is in fact one of the major costs for the MEMS industry. This demonstrator has been characterized and presented at Grundfos Direct Sensors A/S and constitute the preliminary work for a new product which is intended target the low power or wireless pressure sensor for harsh environment market.

  1. Summary on the depressurization from supercritical pressure conditions

    International Nuclear Information System (INIS)

    When a fluid discharges from a high pressure and temperature system, a 'choking' or critical condition occurs, and the flow rate becomes independent of the downstream pressure. During a postulated loss of coolant accident (LOCA) of a water reactor the break flow will be subject to this condition. An accurate estimation of the critical flow rate is important for the evaluation of the reactor safety, because this flow rate controls the loss of coolant inventory and energy from the system, and thus has a significant effect on the accident consequences[1]. In the design of safety systems for a super critical water reactor (SCWR), postulated LOCA transients are particularly important due to the lower coolant inventory compared to a typical PWR for the same power output. This lower coolant inventory would result in a faster transient response of the SCWR, and hence accurate prediction of the critical discharge is mandatory. Under potential two-phase conditions critical flow is dominated by the vapor content or quality of the vapor, which is closely related with the onset of vaporization and the interfacial interaction between phases [2]. This presents a major challenge for the estimation of the flow rate due to the lack of the knowledge of those processes, especially under the conditions of interest for the SCWR. According to the limited data of supercritical fluids, the critical flows at conditions above the pseudo-critical point seem to be fairly stable and consistent witeem to be fairly stable and consistent with the subcritical homogeneous equilibrium model (HEM) model predictions, while having a lower flow rate than those in the two-phase region. Thus the major difficulty in the prediction of the depressurization flow rates remains in the region where two phases co-exist at the top of the vapor dome. In this region, the flow rate is strongly affected by the nozzle geometry and tends to be unstable. Various models for this region have been developed with different assumptions, e.g. the HEM and Moody model [3], and the Henry-Fauske non-equilibrium model [4], and are currently used in subcritical pressure reactor safety design[5]. It appears that some of these models could be reasonably extended to above the thermodynamic pseudo-critical point. The more stable and lower discharge flow rates observed in conditions above the pseudo-critical point suggests that even though SCWR's have a smaller coolant inventory, the safety implications of a LOCA and the subsequent depressurization may not be as severe as expected, this however needs to be confirmed by a rigorous evaluation of the particular event and further evaluation of the critical flow rate. This paper will summarize activities on critical flow models, experimental data and numerical modeling during blowdown from supercritical pressure conditions under the International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on 'Heat Transfer Behaviour and Thermo-hydraulics Code testing for SCWRs'. (authors)

  2. Characterization of contaminant transport by gravity, capillarity and barometric pumping in heterogeneous vadose regimes. 1998 annual progress report

    International Nuclear Information System (INIS)

    'The intent of this research program is to obtain an improved understanding of vadose zone transport processes and to develop field and modeling techniques required to characterize contaminant transport in the unsaturated zone at DOE sites. For surface spills and near-surface leaks of chemicals, the vadose zone may well become a long-term source of contamination for the underlying water table. Transport of contaminants can occur in both the liquid and gas phases of the unsaturated zone. This transport occurs naturally as a result of diffusion, buoyancy forces (gravity), capillarity and barometric pressure variations. In some cases transport can be enhanced by anisotropies present in hydrologic regimes. This is particularly true for gas-phase transport which may be subject to vertical pumping resulting from atmospheric pressure changes. For liquid-phase flows, heterogeneity may enhance the downward transport of contaminants to the water table depending on soil properties and the scale of the surface spill or near-surface leak. Characterization techniques based upon the dynamics of transport processes are likely to yield a better understanding of the potential for contaminant transport at a specific site than methods depending solely on hydrologic properties derived from a borehole. Such dynamic-characterization techniques can be useful for evaluating sites where contamination presently exists as well as for providing an objective basis to evaluate the efficacy of proposed as well as implemented clean-up technologies. The real-time monitoring of processes that may occur during clean-up of tank waste and the mobility of contaminants beneath the Hanford storage tanks during sluicing operations is one example of how techniques developed in this effort can be applied to current remediation problems. In the future, such dynamic-characterization methods might also be used as part of the site-characterization process for determining suitable locations of new DOE facilities that have the potential of introducing contamination into the vadose zone. This report summarizes work and accomplishments at the midpoint of the 3-year project. The authors have pursued the concept of a vadose-zone observatory (VZO) to provide the field laboratory necessary for carrying out the experiments required to achieve the goals of this research. The approach has been: (1) to carry out plume release experiments at a VZO allowing the acquisition of several different kinds of raw data that, (2) are analyzed and evaluated with the aid of highly detailed, diagnostic numerical models. Because the soil properties of a single VZO are unlikely to cover the full range of conditions encountered at all DOE facilities, the authors anticipate studying at least two and possibly three sites spanning a wide range of hydrologic and geologic properties.'

  3. Barometric pumping with a twist: VOC containment and remediation without boreholes. Phase I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    The majority of the planned remediation sites within the DOE complex are contaminated with volatile organic compounds (VOCs). In many instances the contamination has not reached the water table, does not pose an immediate threat, and is not considered a high priority problem. These sites will ultimately require remediation of some type, either by active vapor extraction, bioremediation, or excavation and ex-situ soil treatment. The cost of remediating these sites can range from $50 K to more than $150 K, depending on site characteristics, contaminants, and remediation method. Additionally, for many remediated sites, residual contamination exists which could not practically be removed by the applied remediation technology. These circumstances result in modest sites with contamination of limited risk, but by regulation they must still be controlled. A remediation solution being developed by Science and Engineering Associates, Inc. (SEA) for the Department of Energy serves as an in-situ containment and extraction methodology for sites where most or all of the contamination resides in the vadose zone soil. The approach capitalizes on the advective soil gas movement resulting from barometric pressure oscillations.

  4. Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

    International Nuclear Information System (INIS)

    Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ?1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode

  5. Chlorogenic Acid stability in pressurized liquid extraction conditions.

    Science.gov (United States)

    Wianowska, Dorota; Typek, Rafa?; Dawidowicz, Andrzej L

    2015-03-01

    Chlorogenic acids (CQAs) are phenolic compounds naturally occurring in all higher plants. They are potentially useful in pharmaceuticals, foodstuffs, food additives, and cosmetics due to their recently suggested biomedical activity. Hence, research interest in CQA properties, their isomers, and natural occurrence has been growing. Pressurized liquid extraction (PLE) is regarded as an effective and quick sample preparation method in plant analysis. The short time of PLE decreases the risk of chemical degradation of extracted compounds, thus increasing the attractiveness of its application. However, PLE applied for plant sample preparation is not free from limitations. We found that trans-5-O-caffeoylquinic acid (trans-5-CQA), the main CQA isomer, isomerizes to 3- and 4-O-caffeoylquinic acids and undergoes transesterification, hydrolysis, and reaction with water even in rapid PLE. Moreover, the number and concentration of trans-5-CQA derivatives formed in PLE strongly depends on extractant composition, its pH, and extraction time and temperature. It was not possible to find the PLE conditions in which the transformation process of trans-5-CQA would be eliminated. PMID:25905748

  6. AN APPROXIMATION TO LATERAL EARTH PRESSURES FOR K0 CONDITION

    Directory of Open Access Journals (Sweden)

    M. Arslan TEK?NSOY

    1999-01-01

    Full Text Available In this study, the determination of lateral earth pressures of soils or Ko parameter is considered. For this effect, the deformation and the variations in the shear stresses of the soils placed in an oedometer set up were investigated. Based on this data, a general method which can be used in the calculation of lateral pressures of soils has been proposed. The study was carried out on a cohesive soil having two different group symbol and sandy soils with different relative densities. The lateral pressure values measured by thin wall oedometer technique are in very good agreement with those obtained by calculation. In conclusion, lateral earth pressures or the Ko values are depend upon the distribution of the samples, their relative density and consistancy, the magnitude of the pre-consolidation pressure. The proposed method is a simple and economic technique as regards to the approximation and experimentation.

  7. Pressurizer and steam-generator behavior under PWR transient conditions

    International Nuclear Information System (INIS)

    Experiments have been conducted in the Loss-of-Fluid Test (LOFT) pressurized water reactor (PWR), at the Idaho National Engineering Laboratory, in which transient phenomena arising from accident events with and without reactor scram were studied. The main purpose of the LOFT facility is to provide data for the development of computer codes for PWR transient analyses. Significant thermal-hydraulic differences have been observed between the measured and calculated results for those transients in which the pressurizer and steam generator strongly influence the dominant transient phenomena. Pressurizer and steam generator phenomena that occurred during four specific PWR transients in the LOFT facility are discussed. Two transients were accompanied by pressurizer inflow and a reduction of the heat transfer in the steam generator to a very small value. The other two transients were accompanied by pressurizer outflow while the steam generator behavior was controlled

  8. Analysis of air-conditioning and drying processes using spreadsheet add-in for psychrometric data

    Directory of Open Access Journals (Sweden)

    E.O. Diemuodeke

    2010-01-01

    Full Text Available A spreadsheet add-in for the psychrometric data at any barometric pressure and in the air-conditioning and drying temperatureranges was developed using appropriate correlations. It was then used to simulate and analyse air-conditioning and dryingprocesses in the Microsoft Excel environment by exploiting its spreadsheet and graphic potentials. The package allowsone to determine the properties of humid air at any desired state, and to simulate and analyse air-conditioning as well asdrying processes. This, as a teaching tool, evokes the intellectual curiosity of students and enhances their interest and abilityin the thermodynamics of humid-air processes.

  9. Single particle studies of black liquor gasification under pressurized conditions

    Energy Technology Data Exchange (ETDEWEB)

    Whitty, K.; Backman, R.; Hupa, M.; Backman, P.; Ek, P.; Hulden, S.T.; Kullberg, M.; Sorvari, V.

    1997-10-01

    The purpose of this project is to provide experimental data relevant to pressurized black liquor gasification concepts. Specifically, the following two goals will be achieved: Data on swelling, char yields and component release during pressurized pyrolysis of small samples of black liquor will be obtained. The reactivity and physical behavior of single black liquor droplets during simultaneous pyrolysis and gasification will be investigated. The structure and composition of black liquor char during formation and conversion will be studied. (orig.)

  10. Intelligent fiber optic pressure sensor for measurements in extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Buimistriuc, G. Y. [Instruments Plant Vibrator, 194294, Saint-Petersburg (Russian Federation); Rogov, A. M. [Saint-Petersburg State Technological University, 190013 (Russian Federation)

    2009-07-01

    Application of a fiber optic Fabry-Perot interferometer (FFPI) for measurements of pressure and speed of pressure variation in water reactors of nuclear power plants contributes to improving their safety and long-term metrological stability, which demands for intelligent sensors. It is shown that the manufacturing of a FFPI sensitive element based on a molecular layering nano-technology provides for substantial enhancement of the quality of the gauge. The algorithm of self-calibration of the pressure sensor based on the fact that the length of the FFPI cavity depends on the pressure at a constant spectrum of an optical source is considered. By means of fast tuning of the spectrum of an optical source it is possible to make self-calibration in the course of continuous work of the pressure gauge. It is also shown that the intelligent FFPI pressure sensor maintains metrological characteristics when the total dose of high-neutron/ gamma radiation is over 2 MGy. (authors)

  11. Intelligent fiber optic pressure sensor for measurements in extreme conditions

    International Nuclear Information System (INIS)

    Application of a fiber optic Fabry-Perot interferometer (FFPI) for measurements of pressure and speed of pressure variation in water reactors of nuclear power plants contributes to improving their safety and long-term metrological stability, which demands for intelligent sensors. It is shown that the manufacturing of a FFPI sensitive element based on a molecular layering nano-technology provides for substantial enhancement of the quality of the gauge. The algorithm of self-calibration of the pressure sensor based on the fact that the length of the FFPI cavity depends on the pressure at a constant spectrum of an optical source is considered. By means of fast tuning of the spectrum of an optical source it is possible to make self-calibration in the course of continuous work of the pressure gauge. It is also shown that the intelligent FFPI pressure sensor maintains metrological characteristics when the total dose of high-neutron/ gamma radiation is over 2 MGy. (authors)

  12. CONDITIONS LEADING TO SUDDEN RELEASE OF MAGMA PRESSURE

    Energy Technology Data Exchange (ETDEWEB)

    B. Damjanac; E.S. Gaffney

    2005-08-26

    Buildup of magmatic pressures in a volcanic system can arise from a variety of mechanisms. Numerical models of the response of volcanic structures to buildup of pressures in magma in dikes and conduits provide estimates of the pressures needed to reopen blocked volcanic vents. They also can bound the magnitude of sudden pressure drops in a dike or conduit due to such reopening. Three scenarios are considered: a dike that is sheared off by covolcanic normal faulting, a scoria cone over a conduit that is blocked by in-falling scoria and some length of solidified magma, and a lava flow whose feed has partially solidified due to an interruption of magma supply from below. For faulting, it is found that magma would be able to follow the fault to a new surface eruption. A small increase in magma pressure over that needed to maintain flow prior to faulting is required to open the new path, and the magma pressure needed to maintain flow is lower but still greater than for the original dike. The magma pressure needed to overcome the other types of blockages depends on the details of the blockage. For example, for a scoria cone, it depends on the depth of the slumped scoria and on the depth to which the magma has solidified in the conduit. In general, failure of the blockage is expected to occur by radial hydrofracture just below the blocked length of conduit at magma pressures of 10 MPa or less, resulting in radial dikes. However, this conclusion is based on the assumption that the fluid magma has direct access to the rock surrounding the conduit. If, on the other hand, there is a zone of solidified basalt, still hot enough to deform plastically, surrounding the molten magma in the conduit, this could prevent breakout of a hydrofracture and allow higher pressures to build up. In such cases, pressures could build high enough to deform the overlying strata (scoria cone or lava flow). Models of such deformations suggest the possibility of more violent eruptions resulting from sudden shear failure of a scoria cone with material accelerations near 100 m/s{sup 2}.

  13. Beat Pressure and Comparing it with Ascending Aorta Pressure in Normal and Abnormal Conditions

    CERN Document Server

    Ghasemalizadeh, Omid; Firoozabadi, Bahar; Sajadi, Behrang; Zolfonoon, Ali

    2014-01-01

    Lumped method (Electrical analogy) is a quick and easy way to model human cardiovascular system. In this paper Lumped method is used for simulating a complete model. It describes a 36-vessel model and cardiac system of human body with details that could show hydrodynamic parameters of cardiovascular system. Also this paper includes modeling of pulmonary, atrium, left and right ventricles with their equivalent circuits. Exact modeling of right and left ventricles pressure with division of ascending aorta into 27 segments increases the accuracy of our simulation. In this paper we show that a calculated pressure for aorta from our complex circuit is near to measured pressure by using advanced medical instruments. Also it is shown that pressure graph from brachial is so near to aortic pressure because of this its pressure signal is usable instead of aortic pressure. Furthermore, obstruction in ascending aorta, brachial and its effects has been showed in different figures.

  14. SMART behavior under over-pressurizing accident conditions

    International Nuclear Information System (INIS)

    SMART (system-integrated modular advanced reactor) is an integral reactor of 330 MW capacity with passive safety features under development in Korea. The design is developed by combining the firmly-established commercial reactor technologies with new and advanced technologies such as industry proven KOFA (Korea optimized fuel assembly) based nuclear fuels, self-pressurizing pressurizer, helically coiled once-through steam generators, and new control concepts. The design of SMART focuses on enhancing the safety and reliability of the reactor by employing inherent safety features such as low core power density, elimination of large break loss of coolant accident, etc. In addition, in order to prevent the progression of emergency situations into accidents, the SMART is provided with a number of engineered safety features such as passive residual heat removal system, passive emergency core cooling system, safeguard vessel, and passive containment over-pressure protection system. This paper presents an overview of the SMART design, characteristics of it's safety systems, and results of over-pressure accident analyses. The results of the accident analyses show that the SMART provides the inherent over-pressure protection capability for design basis accidents without actuation of any protection devices such as safety valves, rupture disks, etc. (orig.)

  15. A fórmula barométrica como instrumento de ensino em Química / The barometric formula as resource for teaching Chemistry

    Scientific Electronic Library Online (English)

    Otávio Luiz, Bottecchia.

    1965-19-01

    Full Text Available [...] Abstract in english The barometric equation is revisited. Restrictions imposed for its derivation are investigated. Results are discussed and related to simple themes of ordinary life. The theoretical models fit to experimental data. Correction for temperature effect improves the fitting in comparison to the barometric [...] formula. The scope for application of the model is discussed.

  16. Pressurizer and steam generator behavior under PWR transient conditions

    International Nuclear Information System (INIS)

    Experiments were conducted in the Loss-of-Fluid Test (LOFT) pressurized water reactor (PWR), at the Idaho National Engineering Laboratory, in which transient phenomena arising from accident events with and without reactor scram were studied. The LOFT PWR is a fully operational, 50-MW(t) facility and is related to a commercial PWR through volumetric scaling principles. The main purpose of the LOFT facility is to provide data for the development of computer codes for PWR transient analyses. Significant thermal-hydraulic differences were observed between the measured and calculated results for those transients in which the pressurizer and steam generator strongly influence the dominant transient phenomena. Pressurizer and steam generator phenomena that occurred during four specific PWR transients in the LOFT facility are discussed

  17. Behaviour of polymer muds under high pressure – high temperature conditions

    OpenAIRE

    Larsen, Ha?vard

    2007-01-01

    A well is classified as a HPHT (High Pressure High Temperature) well if the static bottomhole temperatures are greater than 350 °C and when the formation pressures exceed 1800 kg/m3 ECD. Mud weights as high as 2400 kg/m3 may be required to maintain a proper well control. The temperature of the drilling fluid when circulating in the well may range from 0 °C to 150 °C and it is important that the drilling fluid maintain acceptable rheological properties within the whole range. The rheologica...

  18. Generalization of barometric formula for a sollisional plasma in a magnetostatic and rf fields

    International Nuclear Information System (INIS)

    A modification is derived of the barometric formula, describing the plasma density modulation due to nonlinear ponderomotive forces of rf fields implied by collisional diffusion. A one-dimensional model of a fully-ionized plasma is used for simplification. The viscosity and inertia of electrons and the influence of rf fields on ions are neglected. The generalized barometric formula is found as a solution of the Bernoulli-type equation for plasma density derived from the general theory of hydrodynamics. The influence of rf fields on particle fluxes and plasma density is discussed. (J.U.)

  19. Systems and methods of monitoring acoustic pressure to detect a flame condition in a gas turbine

    Science.gov (United States)

    Ziminsky, Willy Steve (Simpsonville, SC); Krull, Anthony Wayne (Anderson, SC); Healy, Timothy Andrew (Simpsonville, SC), Yilmaz, Ertan (Glenville, NY)

    2011-05-17

    A method may detect a flashback condition in a fuel nozzle of a combustor. The method may include obtaining a current acoustic pressure signal from the combustor, analyzing the current acoustic pressure signal to determine current operating frequency information for the combustor, and indicating that the flashback condition exists based at least in part on the current operating frequency information.

  20. Probes for bulk superconductivity in iron pnictide systems under hydrostatic pressure conditions

    International Nuclear Information System (INIS)

    We discuss the sensitivity of iron based superconductors to the hydrostaticity of pressure conditions, which results in discrepancies between different studies. To clarify the situation we present the phase diagram of several systems obtained on single crystals, using the highly hydrostatic pressure conditions of argon in a diamond anvil cell, and an ac susceptibility method to detect superconductivity.

  1. Intra-oral compartment pressures: a biofunctional model and experimental measurements under different conditions of posture

    OpenAIRE

    Engelke, Wilfried; Jung, Klaus; Kno?sel, Michael

    2010-01-01

    Oral posture is considered to have a major influence on the development and reoccurrence of malocclusion. A biofunctional model was tested with the null hypotheses that (1) there are no significant differences between pressures during different oral functions and (2) between pressure measurements in different oral compartments in order to substantiate various postural conditions at rest by intra-oral pressure dynamics. Atmospheric pressure monitoring was simultaneously carried out with a digi...

  2. Pohorje eclogites revisited: Evidence for ultrahigh-pressure metamorphic conditions

    OpenAIRE

    Mirijam Vrabec

    2010-01-01

    Kyanite eclogites from the Pohorje Mountains, Slovenia, are providing the first evidence of ultrahigh-pressureEo-Alpine metamorphism in the Eastern Alps. Polycrystalline quartz inclusions in garnet, omphacite and kyaniteare surrounded by radial fractures and exhibit microtextures diagnostic for the recovery after coesite breakdown.The non-stoichiometric supersilicic omphacites found in Pohorje eclogites contain up to 5 mol % of Ca-Eskola molecule.Such clinopyroxenes are known to be stable exc...

  3. The impact of hepatic pressurization on liver shear wave speed estimates in constrained versus unconstrained conditions

    Science.gov (United States)

    Rotemberg, V.; Palmeri, M.; Nightingale, R.; Rouze, N.; Nightingale, K.

    2012-01-01

    Increased hepatic venous pressure can be observed in patients with advanced liver disease and congestive heart failure. This elevated portal pressure also leads to variation in acoustic radiation-force-derived shear wave-based liver stiffness estimates. These changes in stiffness metrics with hepatic interstitial pressure may confound stiffness-based predictions of liver fibrosis stage. The underlying mechanism for this observed stiffening behavior with pressurization is not well understood and is not explained with commonly used linear elastic mechanical models. An experiment was designed to determine whether the stiffness increase exhibited with hepatic pressurization results from a strain-dependent hyperelastic behavior. Six excised canine livers were subjected to variations in interstitial pressure through cannulation of the portal vein and closure of the hepatic artery and hepatic vein under constrained conditions (in which the liver was not free to expand) and unconstrained conditions. Radiation-force-derived shear wave speed estimates were obtained and correlated with pressure. Estimates of hepatic shear stiffness increased with changes in interstitial pressure over a physiologically relevant range of pressures (0-35 mmHg) from 1.5 to 3.5 m s-1. These increases were observed only under conditions in which the liver was free to expand while pressurized. This behavior is consistent with hyperelastic nonlinear material models that could be used in the future to explore methods for estimating hepatic interstitial pressure noninvasively.

  4. Beat Pressure and Comparing it with Ascending Aorta Pressure in Normal and Abnormal Conditions

    OpenAIRE

    Ghasemalizadeh, Omid; Mirzaee, Mohammad Rreza; Firoozabadi, Bahar; Sajadi, Behrang; Zolfonoon, Ali

    2014-01-01

    Lumped method (Electrical analogy) is a quick and easy way to model human cardiovascular system. In this paper Lumped method is used for simulating a complete model. It describes a 36-vessel model and cardiac system of human body with details that could show hydrodynamic parameters of cardiovascular system. Also this paper includes modeling of pulmonary, atrium, left and right ventricles with their equivalent circuits. Exact modeling of right and left ventricles pressure wit...

  5. Barometric gas transport along faults and its application to nuclear test-ban monitoring

    International Nuclear Information System (INIS)

    Underground nuclear explosions produce a unique but evanescent set of radionuclide gases that potentially can be used in the context of an on-site, test-ban monitoring program to differentiate them from other detected events such as earthquakes or mining activity. In Part I of this report we describe an experiment to evaluate the upward transport of gases from an underground explosion using two gas tracers with very different diffusivities that were released in a 400-m-deep, chemical explosive detonation. The less diffusive (more massive) tracer was detected on a nearby geologic fault 50 days following the detonation while the more diffusive tracer was detected 375 days after release. Computer simulations indicate that the arrival time and the chromatographic behavior of transport are characteristic of barometrically induced flow in a fractured, porous matrix regime. For a hypothetical 1-kiloton fission explosion subject to the same weather and gas transport conditions of the chemical explosion, simulations predict the detectability of argon-37 after 80 days in spite of depletion by radioactive decay. Largely because of the earlier arrival of xenon-133, owing to its lower binary gas diffusivity, the exceedingly short lived isotope should also be detectable - arriving about 30 days earlier than argon. In Part II we consider that our prediction of the detectability of argon and xenon is based upon the small volume (0.00001 m3) sampling technique of the NPE tracer-gas sampling study while actual sampling for radionuclides would involve drawing much larger volume (possibly 0.1-1 m3) gas samples from the near-surface. Extraction of such a large volume of gas from 1-5 meter depths in the soil raises the possibility of significant atmospheric infiltration, leading to substantial dilution of the extracted gas sample. However, an infiltration experiment suggests that significant dilution would not, in fact, occur at the most prolific sampling stations of the earlier gas-tracer study. Of the soil gas being extracted at the shallowest sample site, less than 10% of the gas in the sample volume can be attributed to the infiltration of atmospheric gas. (author)

  6. Analysis of Pressure Fluctuations in a Natural Gas Engine Under Lean Burn Conditions

    OpenAIRE

    Sen, A. K.; G. Litak; Yao, B.-F.; Li, G. -x.

    2009-01-01

    Abstract We have investigated the cycle-to-cycle pressure fluctuations in a natural gas engine under lean burn conditions. In particular, we have examined the dynamics of the indicated mean effective pressure (IMEP) variations for four different values of the equivalence ratio. For each equivalence ratio, we used a continuous wavelet transform to identify the dominant spectral modes and the number of cycles over which these modes may persist. Our results reveal that when the mixtur...

  7. Abiotic Formation of Valine Peptides Under Conditions of High Temperature and High Pressure

    Science.gov (United States)

    Furukawa, Yoshihiro; Otake, Tsubasa; Ishiguro, Takato; Nakazawa, Hiromoto; Kakegawa, Takeshi

    2012-12-01

    We investigated the oligomerization of solid valine and the stabilities of valine and valine peptides under conditions of high temperature (150-200 °C) and high pressure (50-150 MPa). Experiments were performed under non-aqueous condition in order to promote dehydration reaction. After prolonged exposure of monomeric valine to elevated temperatures and pressures, the products were analyzed by liquid chromatography mass spectrometry comparing their retention times and masses. We identified linear peptides that ranged in size from dimer to hexamer, as well as a cyclic dimer. Previous studies that attempted abiotic oligomerization of valine in the absence of a catalyst have never reported valine peptides larger than a dimer. Increased reaction temperature increased the dissociative decomposition of valine and valine peptides to products such as glycine, ?-alanine, ammonia, and amines by processes such as deamination, decarboxylation, and cracking. The amount of residual valine and peptide yields was greater at higher pressures at a given temperature, pressure, and reaction time. This suggests that dissociative decomposition of valine and valine peptides is reduced by pressure. Our findings are relevant to the investigation of diagenetic processes in prebiotic marine sediments where similar pressures occur under water-poor conditions. These findings also suggest that amino acids, such as valine, could have been polymerized to peptides in deep prebiotic marine sediments within a few hundred million years.

  8. Quadratic programming algorithm for wall slip and free boundary pressure condition

    Science.gov (United States)

    Wu, C. W.; Sun, H. X.

    2006-01-01

    Wall slip is often observed in a highly sheared fluid film in a solid gap. This makes a difficulty in mathematical analysis for the hydrodynamic effect because fluid velocity at the liquid-solid interfaces is not known a priori. If the gap has a convergent-divergent wedge, a free boundary pressure condition, i.e. Reynolds pressure boundary condition, is usually used in the outlet zone in numerical solution. This paper, based on finite element method and parametric quadratic programming technique, gives a numerical solution technique for a coupled boundary non-linearity of wall slip and free boundary pressure condition. It is found that the numerical error decreases with the number of elements in a negative power law having an index larger than 2. Our method does not need an iterative process and can simultaneously gives rise to fluid film pressure distribution, wall slip velocity and surface shear stress. Wall slip always decreases the hydrodynamic pressure. Large wall slip even causes a null hydrodynamic pressure in a pure sliding solid gap.

  9. Critical heat flux in rod bundles at low flow and low pressure conditions

    International Nuclear Information System (INIS)

    At low flow and low pressure conditions, Critical Heat Flux (CHF) data for rod-bundle geometry are very limited and applicable design correlations are almost nonexistent. This paper investigates the applicability of recent CHF correlations developed for uniformly heated vertical annuli (for water mass flux ? 250 kg/m2s, and pressure of 0.118 MPa) to rod-bundles. Results show that annuli correlations accurately predict the CHF data in uniformly heated rod-bundles occurring at the same flow-regime transition. Also, the success of the Global Conditions Hypothesis (GCH) in correlating the annuli CHF data suggests that the CHF correlations for annuli, in conjunction with the GCH, may be used to predict CHF in non-uniformly heated rod-bundles, at low flow and low pressure conditions

  10. Charge Accumulation in LDPE and XLPE Conditioned at 80oC under Reduced Pressure

    DEFF Research Database (Denmark)

    Fleming, Robert J.; Henriksen, Mogens

    1997-01-01

    The effects of thermal conditioning, under reduced pressure, on space accumulation in planar LDPE and XLPE samples under DC stress, have been investigated. The samples were conditioned prior to voltage application by being held at 80oC for 2-3 days in short circuit at rotary pump pressure. Some were then cooled to room temperature over a period of at least 6hr, still under rotary pump pressure and in short circuit, while others were cooled to room temperature in less than 1.5hr in the laboratory air. DC fields of 18kV/mm were then applied at room temperature, and space charge accumulation was monitored as a function of time using the PEA (Denmark) and LIPP (Australia) techniques. Conditioning did not prevent space charge accumulation in either the LDPE or XLPE samples.

  11. Boiling heat transfer and dryout in helically coiled tubes under different pressure conditions

    International Nuclear Information System (INIS)

    Highlights: • Heat transfer characteristics and dryout for helically coiled tube are performed. • A boiling heat transfer tends to increase with a pressure increase. • Dryout occurs at high quality test conditions investigated. • Steiner–Taborek’s correlation is predicted well based on the experimental results. - Abstract: A helically coiled once-through steam generator has been used widely during the past several decades for small nuclear power reactors. The heat transfer characteristics and dryout conditions are important to optimal design a helically coiled steam generator. Various experiments with the helically coiled tubes are performed to investigate the heat transfer characteristics and occurrence condition of a dryout. For the investigated experimental conditions, Steiner–Taborek’s correlation is predicted reasonably based on the experimental results. The pressure effect is important for the boiling heat transfer correlation. A boiling heat transfer tends to increase with a pressure increase. However, it is not affected by the pressure change at a low power and low mass flow rate. Dryout occurs at high quality test conditions investigated because a liquid film on the wall exists owing to a centrifugal force of the helical coil

  12. Frictional property of fault gouges in high-velocity and high-fluid pressure condition

    Science.gov (United States)

    Tanikawa, Wataru; Ishikawa, Tsuyoshi; Hirono, Tetsuro; Honda, Go

    2013-04-01

    Fluid in fault zones will influence on fault dynamics and cause water-rock interaction in the fault zone during earthquakes. Frictional heating during friction can increase pore pressure in a fault zone due to the thermal expansion of fluid, and that will reduce the effective normal stress on the fault. This pore pressure rise is also induced by an increase of fluid volume that associates with a dehydration of hydrous minerals or decarbonation of carbonate minerals. Recently laboratory friction experiments demonstrated that high velocity friction can cause remarkable fault weakening and chemical-reaction which is induced by rapid heating during friction. However, a correlation of fluid and pore fluid pressure with friction property and chemical-reaction had not been well investigated. Therefore, we carried out the high velocity friction tests by controlling fluid pressure under high pore pressure condition. We used shale in the fracture zone from the Taiwan Chelungpu Fault Drilling Project (TCDP Hole B, 1090.88 m depth) as simulated gouge materials for friction tests. Shale (Chinshui Shale) is mainly made up by quartz, feldspar, and clay minerals. We made powders with less than 0.125 mm grain size from shale by crushing and sieving. Frictional experiments were performed (1) under constant normal pressure and pore fluid pressure, and (2) under constant normal pressure without controlling pore fluid pressure. Pore pressure was applied from 2 to 5 MPa, and normal stress was from 2 to 12 MPa. We also controlled slip velocity by keeping constant from 0.1 to 0.5 m/s. Total slip displacements were reached to 15 m or 30 m at the end of sliding. In all friction tests, shear strength was decreased with sliding, and then reached to steady state values over ~10 m displacement. For friction tests without controlling pore pressure, pore pressure was gradually increased with sliding. Even though the effective normal stress was decreased by the pore pressure increase, friction coefficient was not changed much. Peak friction was lager for the pore pressure control tests than that for the test without controlling pore pressure. Steady state shear stress was proportional to effective normal stress, and 0.2 of friction coefficient was evaluated for both tests. Temperatures around the slip surface were increased up to 400 degrees Celsius. Lithium concentration in the gouge was decreased after friction tests, and high temperature water-rock interaction at more than 300 degrees Celsius for 60 seconds can explain the anomaly of Lithium concentration. This result agrees with the observation of surface temperature. However, the chemical anomaly we detected was generally small, therefore much higher slip velocity is necessary to occur the water-rock interaction effectively.

  13. Earth tidal and barometric responses observed in the Callovo-Oxfordian formation at ANDRA Meuse/Haute-Marne underground research laboratory

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Fluid pressure or hydraulic head measured in wells in geological formations can respond to Earth tidal forces and atmospheric pressure variations. At Andra Meuse/Haute-Marne underground research laboratory located in Bure (France), water level and fluid pressure are measured in several boreholes in the Callovo-Oxfordian clay formation (COX) and in overlying geological formations. One of these boreholes (EST207) is equipped with a multi-packer system monitoring 11 intervals, including 8 in the COX. The recorded fluid pressures in EST207 were analyzed to determine possible Earth tidal responses. In this borehole, the fluid pressure and atmospheric pressure variations data are recorded every fifteen minutes and 6.5 years of such data from 2004/06/02 to 2010/12/31 were analyzed. Various perturbed data, gaps, drift and abnormal data were corrected through a data preprocessing process. Data interpolation and filtering processes were performed to have data available every 15 minutes at 0, 15, 30 and 45 minutes on the hour. A spectral analysis (Fast Fourier Transform) of each pressure data series shows amplitude peaks at frequencies corresponding to various Earth tidal frequencies: diurnal and semi diurnal waves can be identified. Spectral analyses were also performed on the atmospheric pressure data. The solar semi diurnal wave (S2) was identified. The 'Earth Tides ETERNA package' was used to separate the waves according to s used to separate the waves according to the frequencies bands. The analyses performed using ETERNA are indicated as 'Earth Tidal Analyses' (ETAN). Tidal parameters are estimated from ETAN: amplitudes A and its standard deviation ?(A)[hPa], phase ? for the main waves in diurnal and semi diurnal frequencies bands before and after atmospheric pressure variations correction. The barometric efficiency (BE) and its standard deviation ? (BE) as regression coefficient is calculated. The atmospheric pressure data are also analyzed with ETERNA; the wave S2 amplitude and phase values usually taken into account as references are in good agreement with values calculated at others sites. This result validates the atmospheric pressure data sets. Having high quality data and multi-year data sets, it was possible to separate several main tidal waves in the diurnal band and in the semi diurnal band. K1, O1, P1, S1 and M2, N2, S2, K2 bands were first taken into account in each series to determine whether they were significant or not. The ETAN results are in good agreement with the spectral analyses results and with these results it can be concluded that the 11 monitoring intervals in borehole EST207 respond to Earth Tidal forces and to atmospheric pressure variations. The ETERNA software allows identifying more tidal waves with more accuracy. In all the intervals, the best identified significant waves are O1, K1, M2 and S2. While the M2 amplitude is not or only slightly perturbed by atmospheric pressure variations and the M2 phase is not, the S2 wave amplitude and phase are very sensitive to atmospheric pressure. After barometric correction, the amplitudes through the borehole are generally decreasing from the bottom to the top. In a preliminary hydrogeological interpretation, the detailed intercomparison of tidal analyses results according to the barometric correction effect, the BE values and the waves identification quality provide a classification of the barometric and tidal responses as a function of the various intervals. These responses were classified into four groups depending on the monitoring intervals in the Dogger, the lower COX, the upper COX and the base of Oxfordian. The BE values show that the greater the clay content of the formation is, the greater the BE values are. The BE values in the Dogger are similar to the values estimated in the Oxfordian. In 2003, Andra investigated earth tides and barometric responses in the Oxfordian of two boreholes, EST203 and EST104. The hydrogeological interpretation in these two boreholes provided estimates of transmissi

  14. Determination of optimal conditions for pressure oxidative leaching of Sarcheshmeh Molybdenite concentrate using Taguchi method

    Directory of Open Access Journals (Sweden)

    Khoshnevisana A.

    2012-01-01

    Full Text Available The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO3 with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L25 array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration at five levels were selected for 25 experiments. The experiments were designed and carried out in a high-pressure reactor in the presence of nitric acid as solvent and oxidizing agent for the molybdenite concentrate and its ReS2 content. The optimum conditions for pressure leaching of molybdenite were obtained through using Signal to Noise analysis and modified by using Minitab software prediction tool. Furthermore, the optimum condition for an economical pressure leaching of rhenium sulfide (ReS2 was achieved with the same process. Analysis of variance (ANOVA showed that the pulp density is of paramount importance in this process.

  15. Detectability and significance of 12 hr barometric tide in radon-222 signal, drip water flow rate, air temperature and carbon dioxide concentration in an underground tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Richon, P.; Pili, E. [CEA Bruyeres le Chatel, Dept Analyse Surveillance Environm, 91 (France); Richon, P. [Inst Phys Globe, Equipe Geol Syst Volcan, UMR 7154, F-75252 Paris 05 (France); Perrier, F. [Univ Paris Diderot, Equipe Geomagnetisme, UMR 7154, Inst Phys Globe, F-75252 Paris 05 (France); Sabroux, J. Ch. [CEA Saclay, Inst Radioprotect and Surete Nucl, 91 - Gif-sur-Yvette (France)

    2009-03-15

    Searching for small periodic signals, such as the 12 hr (S{sub 2}) barometric tide, and monitoring their amplitude as a function of time, can provide important clues on the complex processes affecting fluid transport in unsaturated fractured media under multiple influences. Here, first, we show that a modified spectrogram analysis (MSA) is more efficient than simple Fourier transform to reveal weak periodic signals. Secondly, we show how transient periodic signals can be monitored as a function of time using spectrograms. These methods are applied to time-series of radon and carbon dioxide concentration, drip water flow rates and air temperature measured during several years in the Roselend dead-end tunnel, located in the French Alps near an artificial lake. A weak S{sub 2} line is evidenced in radon concentration, with enhanced amplitude during transient radon bursts. Similarly, the S{sub 2} line is observed using MSA in drip water flow rates which sample mainly fracture flow, as suggested by a hydrochemical analysis, while it is not seen in drip water flow rates sampling matrix flow. In the absence of a strong 24 hr line, the presence of a S{sub 2} line suggests sensitivity to barometric pressure, and thus a significant advective contribution in radon and some drip water transport. No S{sub 2} line is observed in the carbon dioxide time-series. The temporal structure of the S{sub 2} component, however, is not similar in the radon concentration and the drip water flow rates, suggesting, in particular, that drip water does not play a significant role in the generation of radon bursts. Temperature time-series exhibit a significant S{sub 2} contribution, induced by atmospheric pressure, spatially organised in the tunnel, decreasing vertically upwards. A remarkable transient temperature inversion during radon bursts suggests that the additional advective air contributions responsible for the radon bursts occur from the non-saturated rocks below the tunnel. (authors)

  16. The lubrication characteristics of the vane tip under pressure boundary condition of oil hydraulic vane pump

    International Nuclear Information System (INIS)

    The lubrication mode of line contacts between the vane and the camring in an oil hydraulic vane pump has been investigated. First, the variations of the radial force of a vane were calculated from previous measurements of dynamic internal pressure in four chambers surrounding a vane. Next, the lubrication modes were distinguished with Hooke's chart, which is an improvement over Johnson's chart. Finally, the influence of the boundary conditions in the lubrication region on the fluid film lubrication was examined by calculating the film pressure distributions. The results showed that the lubrication mode of the vane tip exists in the rigid-variable-viscosity region, and that discharge pressure higher than 7 MPa greatly affects the oil film pressure in the small and the large arc section because of the Piezo-viscous effect

  17. Effect of processing conditions on oil point pressure of moringa oleifera seed.

    Science.gov (United States)

    Aviara, N A; Musa, W B; Owolarafe, O K; Ogunsina, B S; Oluwole, F A

    2015-07-01

    Seed oil expression is an important economic venture in rural Nigeria. The traditional techniques of carrying out the operation is not only energy sapping and time consuming but also wasteful. In order to reduce the tedium involved in the expression of oil from moringa oleifera seed and develop efficient equipment for carrying out the operation, the oil point pressure of the seed was determined under different processing conditions using a laboratory press. The processing conditions employed were moisture content (4.78, 6.00, 8.00 and 10.00 % wet basis), heating temperature (50, 70, 85 and 100 °C) and heating time (15, 20, 25 and 30 min). Results showed that the oil point pressure increased with increase in seed moisture content, but decreased with increase in heating temperature and heating time within the above ranges. Highest oil point pressure value of 1.1239 MPa was obtained at the processing conditions of 10.00 % moisture content, 50 °C heating temperature and 15 min heating time. The lowest oil point pressure obtained was 0.3164 MPa and it occurred at the moisture content of 4.78 %, heating temperature of 100 °C and heating time of 30 min. Analysis of Variance (ANOVA) showed that all the processing variables and their interactions had significant effect on the oil point pressure of moringa oleifera seed at 1 % level of significance. This was further demonstrated using Response Surface Methodology (RSM). Tukey's test and Duncan's Multiple Range Analysis successfully separated the means and a multiple regression equation was used to express the relationship existing between the oil point pressure of moringa oleifera seed and its moisture content, processing temperature, heating time and their interactions. The model yielded coefficients that enabled the oil point pressure of the seed to be predicted with very high coefficient of determination. PMID:26139917

  18. Study on vortex cavitation in a compact fast reactor. Effects of system pressure on inception condition

    International Nuclear Information System (INIS)

    A compact sodium reactor is designed as a commercialized fast reactor cycle system. A 1/10 scaled water experiment was performed to optimize flow in an upper plenum of the reactor vessel, because of high flow velocity resulted from the compacted vessel. In the experiment, vortex cavitation was found at the hot leg inlet because of high velocity in the hot leg pipe (9.4m/s in the design). To evaluate cavitation inception condition of the commercialized reactor, we use the cavitation number k in order to consider the difference of system pressures (0.1MPa in the experiment and 0.3MPa in the design). The minimum pressure at the vortex center will depend on vortex core radius (size of forced vortex region). It is related to axial velocity gradient and fluid viscosity in theory of the Burger's stretched vortex model. We carried out a basic water experiment to investigate the influence of system pressure and fluid viscosity on the vortex cavitation. The cavitation number at the inception of vortex cavitation slightly increased according to the increase of the system pressure. It means that the vortex cavitation occurs easily under higher pressure condition as compared with the similar condition of cavitation number with lower pressure. However the increase was less than 30% when the system pressure was varied from 0.1 to 0.3MPa. The influence of fluid viscosity was examined by change of fluid temperature. Velocity distribution around the vortex was also measured to see the d the vortex was also measured to see the structure of vortex. (authors)

  19. Analysis of boron injection transients in pressurized water reactors at natural circulation conditions

    International Nuclear Information System (INIS)

    The objective of this paper is to analyze boron injection transients at natural circulation conditions in anticipation of preoperational testing in commercial Pressurized Water Reactors (PWRs). The results of the analysis are expected to aid in identifying important phenomena affecting the mixing process and to help to define the measurements needed to assess the results of such tests

  20. Comparison of Extreme Pressure Additive Treat Rates in Soybean and Mineral Oils Under Boundary Lubrication Conditions

    Science.gov (United States)

    Traditionally, it is considered that, under boundary lubrication conditions, the reduction in friction and wear is mostly dependent on Extreme Pressure (EP) additives, rather than the basestock. However, several studies indicate that vegetable oils also contribute to the lubricity under this regime...

  1. Influence of initial and boundary conditions on the formation of reactor pressure vessel thermal shock

    International Nuclear Information System (INIS)

    Influence of initial and boundary conditions on the formation of reactor pressure vessel thermal shock is analyzed by the example of South Ukraine NPP -1 with WWER-1000/V-302. The most conservative scenario for a group of initiating events related to the secondary leaks was obtained in a series of thermal-hydraulic calculations

  2. Effect of Low Pressure End Conditions on Steam Power Plant Performance

    Directory of Open Access Journals (Sweden)

    Ali Syed Haider

    2014-07-01

    Full Text Available Most of the electricity produced throughout the world today is from steam power plants and improving the performance of power plants is crucial to minimize the greenhouse gas emissions and fuel consumption. Energy efficiency of a thermal power plant strongly depends on its boiler-condenser operating conditions. The low pressure end conditions of a condenser have influence on the power output, steam consumption and efficiency of a plant. Hence, the objective this paper is to study the effect of the low pressure end conditions on a steam power plant performance. For the study each component was modelled thermodynamically. Simulation was done and the results showed that performance of the condenser is highly a function of its pressure which in turn depends on the flow rate and temperature of the cooling water. Furthermore, when the condenser pressure increases both net power output and plant efficiency decrease whereas the steam consumption increases. The results can be used to run a steam power cycle at optimum conditions.

  3. Effects of variations in loading conditions on maximum pressure and muzzle velocity when using composite charge

    Directory of Open Access Journals (Sweden)

    V. B. Tawakley

    1960-10-01

    Full Text Available In this paper the effects on maximum pressure and muzzle velocity due to small changes in various quantities defining the loading conditions have been obtained mathematically when using composite charge in guns. Calculations have been done for a particular gun to illustrate these results.

  4. Flare-out condition of Morris-Thorne wormhole and finiteness of pressure

    CERN Document Server

    Kim, Sung-Won

    2013-01-01

    Wormhole is defined as the topological structure with the throat connecting two asymptotically flat spaces. In order to have and maintain the structure of the wormhole, there needs the geometrical flare-out condition, i.e., the minimal size at throat. In the case of Morris-Thorne type wormhole, the condition is given by the huge surface tension compared to the energy density times the square of the light speed. In this paper, we re-considered the flare-out condition for the wormhole with the Einstein equation, checked the finiteness of the pressure, and investigated its physical meaning.

  5. Numerical simulation of pressure fluctuation in 1000MW Francis turbine under small opening condition

    Science.gov (United States)

    Gong, R. Z.; Wang, H. G.; Yao, Y.; Shu, L. F.; Huang, Y. J.

    2012-11-01

    In order to study the cause of abnormal vibration in large Francis turbine under small opening condition, CFD method was adopted to analyze the flow filed and pressure fluctuation. Numerical simulation was performed on the commercial CFD code Ansys FLUENT 12, using DES method. After an effective validation of the computation result, the flow behaviour of internal flow field under small opening condition is analyzed. Pressure fluctuation in different working mode is obtained by unsteady CFD simulation, and results is compared to study its change. Radial force fluctuation is also analyzed. The result shows that the unstable flow under small opening condition leads to an increase of turbine instability in reverse pump mode, and is one possible reason of the abnormal oscillation.

  6. Numerical simulation of pressure fluctuation in 1000MW Francis turbine under small opening condition

    International Nuclear Information System (INIS)

    In order to study the cause of abnormal vibration in large Francis turbine under small opening condition, CFD method was adopted to analyze the flow filed and pressure fluctuation. Numerical simulation was performed on the commercial CFD code Ansys FLUENT 12, using DES method. After an effective validation of the computation result, the flow behaviour of internal flow field under small opening condition is analyzed. Pressure fluctuation in different working mode is obtained by unsteady CFD simulation, and results is compared to study its change. Radial force fluctuation is also analyzed. The result shows that the unstable flow under small opening condition leads to an increase of turbine instability in reverse pump mode, and is one possible reason of the abnormal oscillation.

  7. Flash-type barometric desalination plant powered by waste heat from electricity power stations in Cyprus

    International Nuclear Information System (INIS)

    This paper describes and evaluates the results of a study into the problems of freshwater production and shortages on the island of Cyprus. The use of a novel barometric flash-type desalinator, driven by otherwise waste-heat from the island's power-stations, is proposed as a means of increasing freshwater supplies. Mathematical models are described and used to investigate the thermodynamic performance and economic viability of the proposed system. Although water and electricity-supply data for the island of Cyprus were used for the purposes of this investigation, the overall findings are thought to have a wider applicability

  8. Valve inlet fluid conditions for pressurizer safety and relief valves in combustion engineering-designed plants. Final report

    International Nuclear Information System (INIS)

    The purpose of this study is to assemble documented information for C-E designed plants concerning pressurizer safety and power operated relief valve (PROV) inlet fluid conditions during actuation as calculated by conventional licensing analyses. This information is to be used to assist in the justification of the valve inlet fluid conditions selected for the testing of safety valves and PORVs in the EPRI/PWR Safety/Relief Valve Test Program. Available FSAR/Reload analyses and certain low temperature overpressurization analyses were reviewed to identify the pressurization transients which would actuate the valves, and the corresponding valve inlet fluid conditions. In addition, consideration was given to the Extended High Pressure Liquid Injection event. A general description of each pressurization transient is provided. The specific fluid conditions identified and tabulated for each C-E designed plant for each transient are peak pressurizer pressure, pressure ramp rate at actuation, temperature and fluid state

  9. Improvement of the RELAP5 subcooled boiling model for low pressure conditions

    International Nuclear Information System (INIS)

    The RELAP5/MOD3.2.2 Gamma code was assessed against low pressure subcooled boiling experiments performed by Zeitoun and Shoukri [1] in a vertical annulus. The predictions of subcooled boiling bubbly flow showed that the present version of the RELAP5 code underestimates the void fraction growth along the tube. To improve the void fraction prediction at low pressure conditions a set of model changes is proposed, which includes modifications of bubbly-slug transition criterion, drift-flux model, interphase heat transfer coefficient and wall evaporation modeling. The improved experiment predictions with the modified RELAP5 code are presented and analysed. (author)

  10. Heterogeneous Catalysis under pressure - In-situ neutron diffraction under industrial conditions

    Science.gov (United States)

    Kandemir, Timur; Girgsdies, Frank; Kasatkin, Igor; Kunkes, Edward; Liss, Klaus-Dieter; Peterson, Vanessa K.; Schlögl, Robert; Behrens, Malte

    2012-02-01

    The present work describes the application of a tubular reactor that allows in-situ neutron diffraction on working catalysts at high pressures. The designed reactor enables the application to a sample of industrially-relevant reaction conditions, i.e., in a temperature range up to 330° C and 60 bar pressure, coupled with online gas-analysis. Application of the cell is demonstrated by ammonia synthesis over a commercial catalyst with diffraction data obtained from the high-resolution powder diffractometer, Echidna, at the Australian Nuclear Science and Technology Organisation, ANSTO.

  11. Nonlinear analysis for a double-channel natural circulation loop under low-pressure conditions

    International Nuclear Information System (INIS)

    On the basis of the homogeneous flow model and Galerkin nodal approximation method, a numerical model for a double-channel natural circulation loop is developed. The calculated steady-state results provide a reasonable agreement against the experimental data in the high power region but over-estimate in the low power region under unequal heating conditions for the double channels. Nonlinear dynamics and stability boundary of the system are also analyzed under equal heating power conditions. Two unstable regions, Type-I and Type-II instabilities, are found in this system. In the low inlet subcooling region, the oscillations of the equal-heating double channels are out-of-phase under low power conditions due to the effect of the gravitational pressure drop; however, are in-phase under high power conditions resulting from the effect of the two-phase frictional pressure drop. On the other hand, in the high inlet subcooling region, these double channels are both nearly in-phase at Type-I and Type-II stability boundaries, where the two-phase frictional drop is dominate for the channel pressure drop. (author)

  12. Change of permeability caused by 2011 Tohoku earthquake detected from pore pressure monitoring

    Science.gov (United States)

    Kinoshita, C.; Kano, Y.; Ito, H.

    2013-12-01

    Earthquake-induced groundwater changes which are the pre- and co-seismic changes have been long reported (e.g. Roeloffs, 1996). For example, 1995 Kobe earthquake, water inflow into observation tunnel changed at Rokko (Fujimori et al., 1995), at the times of 1964 Alaska earthquake (M8.6) (Coble, 1967) and 1999 Taiwan Chi-Chi earthquake (M7.6) (Chia et al., 2001), groundwater leve were fluctuated. The shaking of seismic waves and crack formation by crustal deformation are proposed as one causes but the mechanism is controversial. We are monitoring pore pressure from 2005 to measure the stress changes at Kamioka mine, Gifu prefecture, central Japan. Barometric pressure and strain are observed to correct the pore pressure data. In general, the pore pressure changes associate with the meteorological effects, Earth tides and crustal deformation. Increase of pore pressure depends on the precipitation which flows into the ground. Especially, snow effects are bigger than the usual rainfall because our observation site has heavy snow in winter season. Melted snow flows in the ground and pore pressure increases at the March to April every year. When the 2011 Tohoku earthquake (M9.0) occurred, pore pressure remarkably decreased because the permeability increases by crustal deformation at Kamioka region. Thus, we estimated the hydraulic diffusivity before and after the earthquake from pore pressure response to crustal deformation. We made separated analyses on three frequency bands. First is the high frequency band, especially, seismic response. Second is response to Earth tides. Third frequency band is that of barometric response which is lower than other two bands. At high frequency band, we confirmed that the deformation occurred under undrained condition and estimated the bulk modulus from pore pressure and strain data. Next, tidal response is extracted from pore pressure which applied to every three months data of pore pressure, barometric pressure and strain. Time window shifted every one day. As a result, amplitude of O1 and M2 constituents decreased after the Tohoku earthquake. M2 and O1 amplitudes were 0.575 hPa and 0.277 hPa before the earthquake, and decreased to 0.554 hPa and 0.184 hPa after the earthquake respectively. The phase between pore pressure and strain, changed after the event and soon recovered. We estimated the hydraulic diffusivity from the change in ratio of tidal response. We have no strain data due to apparatus problem, so we used synthetic strain. From one-dimensional diffusion equation and poroelastic constitutive relations, we could approximate the relation between pore pressure and strain by the exponential curve. Estimated hydraulic diffusivity of preseismic period is 8.0 m2/s and postseismic period is 19 m2/s, and these results correspond to pore pressure decreases. In the case of the barometric pressure response, we made the spectrum analysis and estimated the hydraulic diffusivity. The results from three frequency domain bands were integrated to show how the hydraulic diffusivity depends on to frequency.

  13. Pressure Gradient Influence on MHD Flow for Generalized Burgers’ Fluid with Slip Condition

    Directory of Open Access Journals (Sweden)

    Ghada H. Ibraheem,

    2014-07-01

    Full Text Available This paper presents a research for magnetohydrodynamic (MHD flow of an incompressible generalized Burgers' fluid including by an accelerating plate and flowing under the action of pressure gradient. Where the no – slip assumption between the wall and the fluid is no longer valid. The fractional calculus approach is introduced to establish the constitutive relationship of the generalized Burgers' fluid. By using the discrete Laplace transform of the sequential fractional derivatives, a closed form solutions for the velocity and shear stress are obtained in terms of Fox H- function for the following two problems: (i flow due to a constant pressure gradient, and (ii flow due to due to a sinusoidal pressure gradient. The solutions for no – slip condition and no magnetic field, can be derived as special cases of our solutions. Furthermore, the effects of various parameters on the velocity distribution characteristics are analyzed and discussed in detail. Comparison between the two cases is also made.

  14. Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

    DEFF Research Database (Denmark)

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures, the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends on the outlet temperature of the gas cooler, the evaporation temperature and the efficiency of the compressor. General correlations for this optimal heat rejection pressure were derived based on cycle simulations. The correlations presented in this paper provide a basisfor designing transcritical carbon dioxide air conditioning or heat pump systems and for intelligent controlling such systems.

  15. Assessment of Fuel Behaviour under Large Break LOCA Condition for Indian Pressurized Heavy Water Reactor

    International Nuclear Information System (INIS)

    Pressurized heavy water reactor (PHWR) consists of a large number of coolant channel assemblies. Each channel assembly is loaded with number of short length fuel bundles. A fuel element consists of sintered cylindrical UO2 pellets contained in a thin collapsible Zircaloy-4 cladding. Large break loss of coolant accident (LBLOCA) in PHWR results in insertion of positive reactivity due to core voiding leading to increase in reactor power. For large breaks, there is an early increase in neutron power and the event leads to reactor trip occurring from neutronic signals besides various other process trips. PHT system depressurizes rapidly and heat transfer from fuel rods decreases sharply which results in rapid rise in clad temperature. With this rise in clad temperature, the exothermic zirconium-metal water reaction would also start contributing toward energy generation and hence results in rapid rise in fuel clad temperature. The fuel clad temperature in the core is estimated during large break LOCA accident and fuel failures in this case are calculated. Under the postulated accident conditions, fuel shall remain in position and not suffer distortion to an extent that would render post- accident core cooling ineffective. The criteria for accident conditions for predicting fuel failure are: (1) The maximum oxygen concentration in the least affected half thickness of clad shall not exceed 0.7 per cent by weight. (2) Stress in the cladding shall not exceed burst stress. (3) adding shall not exceed burst stress. (3) The total energy in fuel element including radial average enthalpy shall be less than 200 cal.g-1 in the over power transient. In an accident transient fuel clad will be subjected to high temperature and high pressure difference across the clad. The coolant pressure goes down in case of large break LOCA. The fission gas pressure is estimated in transient considering fuel temperature and deformation of clad. The fuel element failure is considered if the fuel clad local stress equal or exceeds the burst stresses. The burst stress is calculated considering, clad temperature, differential pressure between clad and coolant and oxidation of the Zircaloy-4 during the transient. In the over power transient initiated by reactivity initiated accident or LOCA, cumulative energy deposition in the fuel is estimated. In this paper, assessment of fuel damage under LBLOCA condition for Indian PHWRs is performed for identified limiting governing break sizes. Analysis demonstrates that under governing LOCA condition with high pressure ECCS available, adequate coolant pressure at the time of peak clad temperature on collapsible clad prevents the gross fuel failure and fuel clad failure is limited to low value of full core in the entire spectrum of break sizes and locations. (author)

  16. The Rheological Properties of Oil-Based Mud under High Pressure and High Temperature Conditions

    Directory of Open Access Journals (Sweden)

    Mahmood Amani

    2012-07-01

    Full Text Available

    Designing a proper drilling fluid that can function properly under the conditions of High-Pressure, High-Temperature (HP/HT operations is very challenging. Among these challenges is the alteration of the rheological properties of drilling fluid due to the high temperature and high pressure (Ibeh et. al, 2007. This work investigates the rheological behavior of oil-based drilling fluids with different properties at Ultra-HP/HT conditions using a state-of-the-art viscometer capable of measuring drilling fluids properties up to 600°F and 40,000 psi. For this purpose, two actual oil based mud samples used by industry with the same mud weight (12.5 ppg were chosen to carry out a matrix of experiments. The results of this study led to concluding that the viscosity, yield point and gel strength decrease with increasing temperature (until the mud sample fails, for oil-based mud with regular formulation. This behavior is the result of the thermal degradation of the solid, polymers, and other components of the mud samples and the expansion of the molecular distances which will lower the resistance of the fluid to flow and, hence, its viscosity, yield point, and gel strength. Moreover, it is concluded that the viscosity and yield point increase as the pressure increases. Pressure’s effect on these parameters, however, is more apparent at low temperature (below failure point, for oil-based mud with regular formulation.

    Key words: High pressure high temperature; Oil-based mud; Rheology; Rheological properties

  17. A modified resistance equation for modeling underwater spark discharge with salinity and high pressure conditions

    International Nuclear Information System (INIS)

    This work investigates the performance of underwater spark discharge relating to bubble growth and decay under high pressure and with salinity conditions by introducing a modified form of the resistance equation. Here, we study salinity influence on circuit parameters by fitting the experimental data for which gap resistance is much larger in conductive water than in dielectric water. Accordingly, the resistance equation is modified by considering the influence of both plasma and its surrounding liquid. Thermal radiation effect of the bubble is also studied by comparing two different radiation models. Numerical results predict a larger bubble pressure for saline water but a reduced size and a smaller bubble cycle at a greater water depth. Such study may be useful in many saltwater applications, including that for deep sea conditions

  18. Inelastic X-ray scattering experiments at extreme conditions: high temperatures and high pressures

    Directory of Open Access Journals (Sweden)

    S.Hosokawa

    2008-03-01

    Full Text Available In this article, we review the present status of experimental techniques under extreme conditions of high temperature and high pressure used for inelastic X-ray scattering (IXS experiments of liquid metals, semiconductors, molten salts, molecular liquids, and supercritical water and methanol. For high temperature experiments, some types of single-crystal sapphire cells were designed depending on the temperature of interest and the sample thickness for the X-ray transmission. Single-crystal diamond X-ray windows attached to the externally heated high-pressure vessel were used for the IXS experiment of supercritical water and methanol. Some typical experimental results are also given, and the perspective of IXS technique under extreme conditions is discussed.

  19. Using weather data from the internet to study how atmospheric pressure varies with altitude

    Science.gov (United States)

    Moya, A. A.

    2014-11-01

    This article presents a simple and motivating activity for schools and colleges that is based on active learning and the use of new technologies to study the variation in atmospheric pressure with height at the lowest altitudes. Students can learn how barometric pressure decreases with height by plotting the atmospheric pressure versus altitude using data obtained from the internet. Using similar methods to those of scientific researchers, the students can learn a practical rule to correct barometric pressure data with altitude, something that is usually expressed at sea level in weather maps.

  20. Structural characterization of eutectic aqueous NaCl solutions under variable temperature and pressure conditions.

    Science.gov (United States)

    Ludl, A-A; Bove, L E; Saitta, A M; Salanne, M; Hansen, T C; Bull, C L; Gaal, R; Klotz, S

    2015-06-01

    The structure of amorphous NaCl solutions produced by fast quenching is studied as a function of pressure, up to 4 GPa, by combined neutron diffraction experiments and classical molecular dynamics simulations. Similarly to LiCl solutions the system amorphizes at ambient pressure in a dense phase structurally similar to the e-HDA phase in pure water. The measurement of the static structure factor as a function of pressure allowed us to validate a new polarizable force field developed by Tazi et al., 2012, never tested under non-ambient conditions. We infer from simulations that the hydration shells of Na(+) cations form well defined octahedra composed of both H2O molecules and Cl(-) anions at low pressure. These octahedra are gradually broken by the seventh neighbour moving into the shell of first neighbours yielding an irregular geometry. In contrast to LiCl solutions and pure water, the system does not show a polyamorphic transition under pressure. This confirms that the existence of polyamorphism relies on the tetrahedral structure of water molecules, which is broken here. PMID:25955540

  1. A SiC high-temperature Pressure Sensor Operating in Severe Condition

    Directory of Open Access Journals (Sweden)

    Guoqing Hu

    2012-12-01

    Full Text Available The tranditional MEMS pressure sensor based on Silicon (Si material has not been suitable for operating in severe condition such as high-temperature (>500°C. However, as an alternative material, Silicon Carbide (SiC can be used in hash environment due to its unique properties. Hence this paper presents a touch mode capacitive pressure sensor with double-notches structure, which employs a special SiC-AlN-SiC sandwich structure to achieve high-accuracy pressure measurement in high-temperature environment. In order to get the relation of capacitance and external pressure, the large deflection theory is applied in simulation analysis of the diaphragm deformation. At the same time, the sandwich structure and technical process of the sensor are studied in the paper. The results showed that the sensor has excellent high-temperature performance due to application of SiC and AlN materials, and the sensor has higher sensitivity and longer linear range than traditional single-cavity structure. Consequently, the sensor can be applied to accuracy pressure measuremet in high-temperature and harsh environment.

  2. Durability of polydicyclopentadiene under high temperature, high pressure and seawater (offshore oil production conditions)

    OpenAIRE

    Le Gac, Pierre-yves; Choqueuse, Dominique; Paris, Marc; Recher, G.; Zimmer, Celine; Melot, D.

    2013-01-01

    In the offshore industry polymer coatings are widely used to ensure thermal insulation of steel pipes, and to avoid over-cooling of the hot oil inside. Because of very severe service conditions (i.e. high temperature, high pressure and presence of seawater) and an expected life time of 20 years, durability of these coatings is a major issue for this industry. Polypropylene and polyurethane are often used for this application, nevertheless these polymers have some limitations in terms of proce...

  3. Pressure Measurements in an Axial Compressor: from Design Operating Conditions to Rotating Stall Inception

    OpenAIRE

    VEGLIO, Monica; Dazin, Antoine; ROUSSETTE, Olivier; BOIS, Gérard

    2014-01-01

    The reduction of the environmental impact is nowadays the crucial challenge for the aeronautic industry. The following of a lower consumption of the vehicles has led to more compact and high loaded engines, increasing the internal flow unsteadiness and the occurrence of unstable phenomena, especially for compression stages. In this work the casing pressure characteristics in a single stage axial compressor both for normal-to-stall transient regime and for stalled conditions will be discussed....

  4. Modeling and Investigation of Electromechanical Valve Train Actuator at simulated Pressure conditions

    DEFF Research Database (Denmark)

    Habib, Tufail

    2012-01-01

    In an electromechanical valve actuated engine, the valves are driven by solenoid-type actuators and cam-shaft is eliminated. Control of each valve provides flexibility in valve timings over all engine conditions and achieves the benefits of variable valve timing(VVT). This paper is about investigation of Electro-mechanical actuator at simulated pressure conditions for a single cylinder engine. For this purpose, a scaled down actuator with reduced armature lift and high stiffness springs are being used. Experiments are conducted to measure valve release timings, transition times and contact velocities. Furthermore, discussion about the spring, magnetic, exhausts gas forces and their ability to actuate the system as desired.

  5. Novel Techniques for High Pressure Falling Sphere Viscosimetry under Simulated Earth's Mantle Conditions

    Science.gov (United States)

    Mueller, H. J.; Beckmann, F.; Dobson, D. P.; Hunt, S. A.; Secco, R.; Lauterjung, J.; Lathe, C.

    2014-12-01

    Viscosity data of melts measured under in situ high pressure conditions are crucial for the understanding of Earth's lower mantle and the interior of terrestrial and extrasolar Super-Earth planets. We report recent technical advances and techniques enabling falling sphere viscosity measurements in single- and double-stage DIA-type multi-anvil apparatus. For the experiments we used presses with a maximum load of 250 tons and 1750 tons. We anticipate that our system will enable viscosity measurements up to the maximum pressure for non-diamond anvils, i.e. pressures up to some 30 GPa. For the development of the new set ups the deformation of the cell assemblies were analyzed by X-ray absorption tomography at beamline W II at DESY/HASYLAB after the high pressure runs. These analysis gave considerable insights into strategies for improving the cell assembly with the result that the optimized assemblies could be used at much higher pressures without blow-outs. We think this approach is much faster and more beneficial than the classical way of trial and error. Additionally to prevent high pressure blow outs the task was to make the whole melting chamber accessible for the high pressure X-radiography system up to the maximum pressures. This way the accuracy and reliability of the measurements can be improved. For this goal we used X-ray transparent cBN-anvils at the single-stage DIA large volume press. Because this material is recently not available for the cube size of 32 mm this aproach did not work for the double-stage DIA. As a very useful and economical alternative we used slotted carbide anvils filled with fired pyrophyllite bars. To improve the frame quality of the platinum spheres taken by the CCD-camera the energy of the monochromatic X-rays had to be increased to 100 keV. The resulting ascent of scattered radiation required a new design of the X-radiography unit. Our results are demonstrated with viscosity measurements following Stokes law by evaluation of X-radiography sequences taken by a CCD-camera at pressures of 5 GPa as well as 10 GPa and temperatures of 1890 K. As the first result we could increase the maximum pressure range of published viscosity measurements with dacite melts by almost factor 1.5 (see Tinker et al., 2004).

  6. Flare-out condition of a Morris-Thorne wormhole and finiteness of pressure

    Science.gov (United States)

    Kim, Sung-Won

    2013-11-01

    A wormhole is defined as a topological structure with a throat connecting two asymptotically-flat spaces. In order to have and maintain the structure of the wormhole, a geometrical flare-out condition, i.e., a minimal size at throat, needs to be satisfied. In the case of a Morris-Thorne-type wormhole, the condition is given by surface tension which is huge compared to the energy density times the square of the light speed. In this paper, we re-considered the flare-out condition for a wormhole by using the Einstein equation, checked the finiteness of the pressure, and investigated its physical meaning. We also derived the power-law form of the flare-out condition.

  7. A test facility for heat transfer, pressure drop and stability studies under supercritical conditions

    International Nuclear Information System (INIS)

    Supercritical water (SCW) exhibits excellent heat transfer characteristics and high volumetric expansion coefficient (hence high mass flow rates in natural circulation systems) near pseudo-critical temperature. SCW is being considered as a coolant in some advanced nuclear reactor designs on account of its potential to offer high thermal efficiency, compact size, elimination of steam generator, separator and dryer, making it economically competitive. The elimination of phase change results in elimination of the Critical Heat Flux (CHF) phenomenon. Cooling a reactor at full power with natural instead of forced circulation is generally considered as enhancement of passive safety. In view of this, it is essential to study natural circulation, heat transfer and pressure drop characteristics of supercritical fluids. Carbon-dioxide can be considered to be a good simulant of water for natural circulation at supercritical conditions since the density and viscosity variation of carbon-dioxide follows a parallel curve as that of water at supercritical conditions. Hence, a supercritical pressure natural circulation loop (SPNCL) has been set up in Hall-7, BARC to investigate the heat transfer, pressure drop and stability characteristics of supercritical carbon-dioxide under natural circulation conditions. The details of the experimental facility are presented in this report. (author)

  8. Wall pressure and conditional flow structures downstream of a reattaching flow region

    International Nuclear Information System (INIS)

    Highlights: ? Investigation of the separating and reattaching flow over a thick plate. ? Analysis of the evolution of the large scale vortices downstream of the reattachment. ? Stochastic estimation of the velocity correlated with the fluctuating wall pressure. ? Use of swirling strength and FTLE to detect and characterize the coherent structures. ? Observation of a rapid loss of coherence of vortices downstream of the reattachment. - Abstract: The separating and reattaching flow over a thick plate with sharp angle at Re = 80,000 is investigated using pressure and HS-PIV measurements. After having studied the mean flow properties, which are found in good agreement with the literature, a particular emphasis is given concerning the eduction and the analysis of the evolution of the large scale vortices downstream of the reattachment. This is done using an adapted multi-time and multichannel stochastic estimation of the velocity correlated with the fluctuating wall pressure. Swirling strength and Finite Time Lyapunov Exponents are then used in order to detect and characterize the structures and their dynamics. Conditional statistics based on the feature longitudinal position are computed in order to educe intensity, size, position and convection velocity of each conditional feature. A rapid longitudinal decrease of the fluctuating kinetic energy carried by these conditional structures has been observed, highlighting their rapid loss of coherence downstream mean ss of coherence downstream mean reattachment.

  9. Equation of state for solids with high accuracy and satisfying the limitation condition at high pressure

    International Nuclear Information System (INIS)

    An equation of state (EOS) with high accuracy is proposed to strictly satisfy the Fermi gas limitation condition at high pressure. The EOS (SJX EOS) is a modification of the effective Rydberg (ER2) EOS. Instead of Holzapfel's method to directly modify the ER2 EOS, one modifying term is added to the ER2 EOS to make it not only satisfy the high pressure limitation condition, but also to avoid the disadvantages occurring in the Holzapfel and 'adapted polynomial expansion of the order 3' (AP3) EOSs. The two-parameter ER2, Holzapfel, and three-parameter SJX, AP3, Kumari and Dass (KD) EOSs are applied to 50 materials to fit all experimental compression data available. The five EOSs also are applied to 37 of the 50 materials to fit experimental compression data at low-pressure ranges. The results show that for all pressure ranges the AP3 EOS gives the best fitting results; the SJX, ER2, Holzapfel and KD EOSs sequentially give inferior results. Otherwise, it is shown that the values of B0, B0' and B0'' are different for different EOSs and also, within one EOS, for high and low-pressure ranges. The SJX EOS gives the best consistency between the values obtained by fitting all experimental data available, and the experimental data at low-pressure ranges, respectively. The AP3 EOS gives the worst results. The differences of the values of B0, B0' and B0'' obtained for the sub>0'' obtained for the ER2, Holzapfel and KD EOSs with those obtained for the SJX EOS are large at high-pressure ranges, but decrease at low-pressure ranges. At present, the newest experimental compression data, within the widest compression range, are available for solid n-H2. The values of B0, B0' and B0'' fitted by using the SJX EOS are almost in agreement with these experimental data. The ER2 EOS gives inferior values, and other EOSs give fairly bad results. For the predicted compression curves and the cohesive energy, the SJX EOS gives the best results; the AP3 EOS gives the worst results, even for many solids the AP3 EOS cannot give physically correct results for the cohesive energy. The analysis shows that for such solids, the variation of pressure and energy versus compression ratio calculated by using the AP3 EOS would oscillate, physically incorrectly. Although the AP3 EOS has the best fitting ability to the pressures, it has the worst predicting ability, and fails to be a universal EOS. The SJX EOS is recommended and can be taken as a candidate of universal EOSs to predict compression curves of solids in a wide pressure range only using the values of B0, B0' and B0'' obtained from low-pressure data

  10. Melatonin analogue agomelatine reduces rabbit's intraocular pressure in normotensive and hypertensive conditions.

    Science.gov (United States)

    Martínez-Águila, Alejandro; Fonseca, Begoña; Bergua, Antonio; Pintor, Jesús

    2013-02-15

    In the search for new compounds to reduce intraocular pressure (IOP), with fewer side effects, we have found that agomelatine, a melatonin analogue, can reduce IOP being, therefore, interesting for the treatment of ocular hypertension and glaucoma. In normotensive conditions, agomelatine (10?l 100?M) reduced IOP by 20.8±1.4% (n=18) with a maximal effect 180min after the compound application and 68.8±5.7% (n=8) in a hypertensive condition. Concentration-response curve depicted a sigmoid behaviour presenting a pD2 value of 9.7±0.3 which was equivalent to an EC50 of 0.19nM. The effect of agomelatine was partially antagonized by 4PPDOT (MT2 antagonist receptor. 10?l 100?M) and prazosin (MT3 antagonist receptor. 10?l 100?M) (85.6±1.6% and 87.2±1.9%, N=18 respectively.) Agomelatine hypotensive effect in normotensive condition was comparable to latanoprost (40?l) and brimonidine (40?l) and it was no so effective as dorzolamide (40?l) or timolol (40?l). These results may suggest the use of this melatonin analogue for the treatment of those ocular conditions, which involve an abnormal raise of intraocular pressure. PMID:23270715

  11. Type-locality granulites: high-pressure rocks formed at eclogite-facies conditions

    Science.gov (United States)

    O'Brien, P. J.

    2006-03-01

    The type-locality granulites from the Granulitgebirge of Saxony, Germany, are rocks of broadly granitic composition containing minor garnet and kyanite within a commonly mylonitised matrix of feldspars and quartz. Petrographic evidence indicates a primary assemblage of ternary feldspar + quartz + garnet + kyanite + rutile, most likely resulting from partial melting of a granitic protolith, for which equilibrium temperature and pressure conditions of >1000 °C and >1.5 GPa have been deduced. These extreme (for crustal rocks) conditions, and the inferred peak assemblage, are supported by the newly-developed Zr-in-rutile geothermometer and experimental studies on the same bulk composition, respectively. As these conditions lie above those required for plagioclase stability in quartz tholeiites, they are thus in the eclogite facies. Widespread modification of the peak assemblage, for example mesoperthite formation after ternary feldspar, deformation-induced recrystallisation of perthites to two-feldspar + quartz aggregates, biotite replacing garnet, Ca-loss at garnet rims, sillimanite replacing kyanite or secondary garnet growth, makes reliable interpretation of equilibrium assemblages and compositions very difficult and explains the spread of published pressure-temperature values and consequent confusion about formation depths and the validity of tectonometamorphic models. Such extreme metamorphic conditions in rock compositions typical for the upper continental crust, reflecting a hot subduction environment, has important consequences for understanding some collisional orogens.

  12. Effect of Antecedent Conditions on Prediction of Pore-Water Pressure using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Muhammad Raza Ul Mustafa

    2012-01-01

    Full Text Available The effect of antecedent conditions on the prediction of soil pore-water pressure (PWP using Artificial Neural Network (ANN was evaluated using a multilayer feed forward (MLFF type ANN model. The Scaled Conjugate Gradient (SCG training algorithm was used for training the ANN. Time series data of rainfall and PWP was used for training and testing the ANN model. In the training stage, time series of rainfall was used as input data and corresponding time series of PWP was used as the target output. In the testing stage, data from a different time period was used as input and the corresponding time series of pore-water pressure was predicted. The performance of the model was evaluated using statistical measures of root mean square error and coefficient of determination. The results of the model prediction revealed that when antecedent conditions (past rainfall and past pore-water pressures are included in the model input data, the prediction accuracy improves significantly.

  13. Core void fraction distribution under high-temperature high-pressure boil-off conditions

    International Nuclear Information System (INIS)

    The prediction of void fraction distributions in a core under boil-off conditions is important for analyzing the core cooling performance during reactor accidents. In this work, boil-off experiments were conducted under high-temperature high-pressure conditions using PWR-type and tight-lattice type (p/d = 1.11) simulated fuel assembly test sections of the Two-Phase flow Test Facility (TPTF). Several existing void fraction correlations and models were assessed against the experimental data. As a result, it has become clear that: 1) while the Chexal-Lellouche model predicts best the present experimental data, the model has a tendency to underestimate void fraction at higher pressures; 2) no significant problems are found in the applicability of the tested correlations and models to the tight-lattice geometry; and 3) void fractions measured by single-beam gamma densitometers tend to be larger than those measured by differential pressure transducers due to the radial void fraction distribution. (author)

  14. Critical heat fluxes in tubes under conditions of subcooled boiling and low pressures

    International Nuclear Information System (INIS)

    A problem of measuring critical heat loading qsub(cr) in channels of different configuration at relatively low pressures appeared to be especially actual in connection with plans of a wide range construction of reactors for nuclear boilers of high-energy voltaged experimental reactors. Measurement results of qsub(cr) under conditions of forced water circulation in the tube with d approximately 8 mm for the pressure range from 0.5 to 3.0 MPa are presented. The experimental data are compared with calculational results. The qsub(cr) measurements have been carried out at the experimental flowsheet which is a closed circuit. A working section is a tube made of the Kh18N10T of the plant production soldered into current-guides. The working section lengths are 240 and 400 mm. The working section has been heated by alternating current. Critical conditions have been obtained by the way of continuous increase of heat flux or decrease of subcooled boiling of the coolant at the inlet of the channel. A formula for critical heat fluxes calculation under conditions of stable two-phase current is recommended in the result of experimental data analysis. The formula permits to take into consideration the channel geometry and conditions in the flux before heating. The formula provides satisfactory accuracy of qsub(cr) determination in tubes with internal diameter of approximately 8 mm for the pressure range of 0.5 MPa 22xs), consumed steam contents x<=-0.05. In the most of these cases the accuracy appears not inferior than +-15%

  15. Behavior of surface flaws in reactor pressure vessels under thermal-shock loading conditions

    International Nuclear Information System (INIS)

    This paper discusses the conditions necessary for crack propagation during a loss of coolant accident (LOCA), the detailed behavior of the cracks under these specific conditions, and an experimental program designed to determine the validity of the method of analysis (linear-elastic fracture mechanics) used to predict the behavior of flaws under severe thermal-shock loading conditions. A detailed fracture-mechanics analysis of the LOCA thermal shock was performed to help establish the scope of the experimental program. The results of this analysis indicate that present-generation and future pressurized water reactor (PWR) vessels will not experience excessive crack propagation. This is also true of earlier PWR vessels, which contain rather high concentrations of copper. The agreement between experimental results and the LEFM analysis was very good. 14 refs

  16. Sulphation of oil shale ash under atmospheric and pressurized combustion conditions

    International Nuclear Information System (INIS)

    One of the main problems in conventional combustion boilers firing pulverized oil shale is the corrosion and fouling of heating surfaces, which is caused by sulphur compounds. Another major problem, from the environmental point of view, are the high SO2 emissions. Consequently, the amount of sulphur in flue gases must be reduced. One alternative to lower the SO2, concentration is the use of new technologies, such as pressurized fluidized bed combustion (PFBC). In FBC processes, the sulphur components are usually removed by the addition of limestone (CaCO3) or dolomite (CaCO3 x MgCO3) into the bed. The calcium in these absorbents react with SO2, producing solid CaSO4. However, when burning oil shale, there would be no need to add limestone or dolomite into the bed, due to the initially high limestone content in the fuel (molar ratio Ca/S =10). The capture of sulphur by oil shale ashes has been studied using a pressurized thermogravimetric apparatus (PTGA). The chosen experimental conditions were typical for atmospheric and pressurized fluidized bed combustion. Four different materials were tested - one cyclone ash from an Estonian oil shale boiler, two size fractions of Estonian oil shale and, one fraction of Israeli oil shale. The cyclone ash was found to be the poorest sulphur absorbent. In general, the results from the sulphur capture experiments under both atmospheric and pressurized fluidized bed conditions showed that the oil shale can capture not only its own sulphur but also significant amounts of additional sulphur from another fuel if the fuels are mixed together. (author)

  17. Windsock memory conditioned RAM (Co-Ram) pressure effect: forced reconnection in the Earth's magnetotail

    CERN Document Server

    Vörös, Z; Khodachenko, M; Honkonen, I; Janhunen, P; Palmroth, M

    2014-01-01

    Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by \\citet{dung63}, can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its numerous modifications were able to explain fully the onset conditions for MR in the tail. In this paper, we introduce new onset conditions for forced MR in the tail. We call our scenario the "windsock memory conditioned ram pressure effect". Our non-flux-transfer associated forcing is introduced by a combination of large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented IMF. Using global MHD GUMICS-4 simulation results, upstream data from WIND, magnetosheath data from Cluster-1 and distant-tail data from the two-probe ARTEMIS mission, we show that the simultaneo...

  18. Estimation of pressure-, temperature- and frictional heating-related effects on proteins' retention under ultra-high-pressure liquid chromatographic conditions.

    Science.gov (United States)

    Fekete, Szabolcs; Guillarme, Davy

    2015-05-01

    The goal of this work was to evaluate the changes in retention induced by frictional heating, pressure and temperature under ultra high pressure liquid chromatography (UHPLC) conditions, for four model proteins (i.e. lysozyme, myoglobin, fligrastim and interferon alpha-2A) possessing molecular weights between 14 and 20kDa. First of all, because the decrease of the molar volume upon adsorption onto a hydrophobic surface was more pronounced for large molecules such as proteins, the impact of pressure appears to overcome the frictional heating effects. Nevertheless, we have also demonstrated that the retention decrease due to frictional heating was not negligible with such large biomolecules in the variable inlet pressure mode. Secondly, it is clearly shown that the modification of retention under various pressure and temperature conditions cannot be explained solely by the frictional heating and pressure effects. Indeed, some very uncommon van't Hoff plots (concave plots with a maximum) were recorded for our model/therapeutic proteins. These maximum retention factors values on the van't Hoff plots indicate a probable change of secondary structure/conformation with pressure and temperature. Based on these observations, it seems that the combination of pressure and temperature causes the protein denaturation and this folding-unfolding procedure is clearly protein dependent. PMID:25823888

  19. Numerical characterization of pressure instabilities in a vaned centrifugal pump under partload condition

    Science.gov (United States)

    Yang, J.; Pavesi, G.; Cavazzini, G.; Yuan, S. Q.

    2013-12-01

    This paper studies the hysteresis/saddle phenomena of the head-drop in a scaled model pump turbine using CFD methods. This lag was induced by complicated flow patterns, which influenced the reliability of rotating machine that was analysed by a commercial code with DES model for computing turbulence. Analyses were carried out on the pressure signals both in frequency and time-frequency domains at full and part load conditions. The results highlighted the remarkable interaction between the unsteady structures in diffuser and return.

  20. Finite Element Simulation of Photoacoustic Pressure in a Resonant Photoacoustic Cell Using Lossy Boundary Conditions

    DEFF Research Database (Denmark)

    Duggen, Lars; Lopes, Natasha

    2011-01-01

    The finite-element method (FEM) is used to simulate the photoacoustic signal in a cylindrical resonant photoacoustic cell. Simulations include loss effects near the cell walls that appear in the boundary conditions for the inhomogeneous Helmholtz equation governing the acoustic pressure. Reasonably good agreement is obtained between theoretical results and experimental data. However, it was anticipated that loss mechanisms other than viscous and thermal boundary losses occur and should be included. Nevertheless, the feasibility to use FEM together with the derived boundary conditions to simulate the photoacoustic signal was demonstrated and good agreement with experiments for the actual resonance frequency and the quality factor of the cell was obtained despite its complicated geometry.

  1. Meshfree finite differences for vector Poisson and pressure Poisson equations with electric boundary conditions

    CERN Document Server

    Zhou, Dong; Shirokoff, David; Chidyagwai, Prince; Rosales, Rodolfo Ruben

    2013-01-01

    We demonstrate how meshfree finite difference methods can be applied to solve vector Poisson problems with electric boundary conditions. In these, the tangential velocity and the incompressibility of the vector field are prescribed at the boundary. Even on irregular domains with only convex corners, canonical nodal-based finite elements may converge to the wrong solution due to a version of the Babuska paradox. In turn, straightforward meshfree finite differences converge to the true solution, and even high-order accuracy can be achieved in a simple fashion. The methodology is then extended to a specific pressure Poisson equation reformulation of the Navier-Stokes equations that possesses the same type of boundary conditions. The resulting numerical approach is second order accurate and allows for a simple switching between an explicit and implicit treatment of the viscosity terms.

  2. The osmotic pressure of highly concentrated monoclonal antibody solutions: effect of solution conditions.

    Science.gov (United States)

    Binabaji, Elaheh; Rao, Suma; Zydney, Andrew L

    2014-03-01

    The behavior of monoclonal antibodies at high concentrations is important in downstream processing, drug formulation, and drug delivery. The objective of this study was to evaluate the osmotic pressure of a highly purified monoclonal antibody at concentrations up to 250 g/L over a range of pH and ionic strength, and in the presence of specific excipients, using membrane osmometry. Independent measurements of the second virial coefficient were obtained using self-interaction chromatography, and the net protein charge was evaluated using electrophoretic light scattering. The osmotic pressure at pH 5 and low ionic strength was >50 kPa for antibody concentrations above 200 g/L. The second virial coefficients determined from the oncotic pressure (after subtracting the Donnan contribution) were in good qualitative agreement with those determined by self-interaction chromatography. The second virial coefficient decreased with increasing ionic strength and increasing pH due to the reduction in intermolecular electrostatic repulsion. The third virial coefficient was negative under all conditions, suggesting that multi-body interactions in this system are attractive. The virial coefficients were essentially unaffected by addition of sucrose or proline. These results have important implications for the analysis of protein-protein interactions in downstream processing at high protein concentrations. PMID:23996891

  3. Liquid Fuel Emulsion Jet-in-Crossflow Penetration and Dispersion Under High Pressure Conditions

    Science.gov (United States)

    Gomez, Guillermo Andres

    The current work focuses on the jet-in-crossflow penetration and dispersion behavior of water-in-oil emulsions in a high pressure environment. Both fuel injection strategies of using a water-in-oil emulsion and a jet-in-crossflow have demonstrated unique benefits in improving gas turbine performance from an emissions and efficiency standpoint. A jet-in-crossflow is very practical for use in gas turbine engines, rocket propulsion, and aircraft engines since it utilizes already available crossflow air to atomize fuel. Injecting water into a combustion chamber in the form of a water-in-oil emulsion allows for pollutant emissions reduction while reducing efficiency loses that may result from using a separate water or steam injection circuit. Dispersion effects on oil droplets are expected, therefore investigating the distribution of both oil and water droplets in the crossflow is an objective in this work. Understanding the synchronization and injection behavior of the two strategies is of key interest due to their combined benefits. A water-to-oil ratio and an ambient pressure parameter are developed for emulsion jet-in-crossflow trajectories. To this end, a total of 24 emulsion jet-in-crossflow tests were performed with varying ambient pressures of 2-8 atm and momentum flux ratios of 50, 85, and 120. Sobel edge filtering was applied to each averaged image obtained from a high speed video of each test case. Averaged and filtered images were used to resolve top and bottom edges of the trajectory in addition to the overall peak intensity up to 40 mm downstream of the injection point. An optimized correlation was established and found to differ from literature based correlations obtained under atmospheric pressure conditions. Overall it was found that additional parameters were not necessary for the top edge and peak intensity correlations, but a need for a unique emulsion bottom edge and width trajectory correlation was recognized. In addition to investigating emulsion jet-in-crossflow trajectory correlations, a unique Dual Planar Laser Induced Fluorescence (Dual-PLIF) method was applied for the first time on emulsions at elevated pressure conditions. From the Dual-PLIF results, qualitative observations provided insight into the unique dispersion of oil and water concentrations within a cross-sectional plane down stream of the jet-in-crossflow injection.

  4. CFD simulation of pressure and discharge surge in Francis turbine at off-design conditions

    Science.gov (United States)

    Chirkov, D.; Avdyushenko, A.; Panov, L.; Bannikov, D.; Cherny, S.; Skorospelov, V.; Pylev, I.

    2012-11-01

    A hybrid 1D-3D CFD model is developed for the numerical simulation of pressure and discharge surge in hydraulic power plants. The most essential part - the turbine itself - is simulated directly using 3D unsteady equations of turbulent motion of fluid-vapor mixture, while the rest of the hydraulic system is simulated in frames of 1D hydro-acoustic model. Thus the model accounts for the main factors responsible for excitation and propagation of pressure and discharge waves in hydraulic power plant. Boundary conditions at penstock inlet and draft tube outlet are discussed in detail. Then simulations of dynamic behavior at part load and full load operating points are performed. It is shown that the numerical model is able to capture self-excited oscillations in full load conditions. The influence of penstock length and flow structure behind the runner are investigated. The presented approach seems to be a promising tool for prediction and investigation the dynamic behavior in hydraulic power plants.

  5. Polymerization Experiment Of Amino Acids Under High Pressure And Temperature Conditions Simulating The Deep Lithosphere

    Science.gov (United States)

    Ohara, S.; Kakegawa, T.; Nakazawa, H.

    2005-12-01

    Chemical evolution in deep sea or deep lithosphere is one of the popular hypotheses for the origin of life on the early Earth. In such hypothesis, effects of pressure and temperature on polymerization (and/or stability) of amino acids needed to be evaluated. In this study, high temperature and pressure experiments were performed using of a test-tube-type autoclave for polymerization of amino acids. Approximately 100 mg of Glycine powder were placed into sterilized gold capsule. Multiple experiments were done at 150 degrees for 1 to 8 days at variable pressures (25MPa, 50MPa, 75MPa and 100MPa). Glycine peptides were identified and quantified by high performance liquid chromatography (HPLC). Each capsule was opened carefully and 1 ml of mobile phase was added to release the amino acids and oligopeptide from the solid phase. Liquid phases were separated by the cetrifugal method. Peptides were identified by retention times of authentic reference substances. The reaction yields were determined as percentage of the reactant converted to the reaction product. Pligopeptides more than hexamer were additionally identified by the detection of the molecular ion by liquid chromatography mass spectrometry (LC / MS). A HPLC chromatogram of the products indicated at least seven oligomers: diketopiperazine (cyc(Gly)2), di-glycine (Gly2), tri-glycine (Gly3), tetra-glycine (Gly4), penta-glycine (Gly5) and hexa-glycine (Gly6). We also identified hepta-glycine (Gly7), octa-glycine (Gly8) and nona-glycine (Gly9) with LC/MS. This is the first report that up to nona-glycine was synthesized under high temperature and pressure conditions. In addition, our experiments indicate that polymerization occurs wide range of pressure from 25 to 100 MPa. On the other hand, yields of total amounts of peptide did not change with pressure, suggesting that an unknown process in the autoclave is limiting the yield. We speculate the activity of water vapor, generated by peptide formation reaction, controlled the yield in the autoclave. The results from this study support the theory that chemical evolution could happen in deep Earth environments, such as inside of lithosphere.

  6. Use of a CFD-tool for assessment of the reactor pressure vessel integrity in pressure thermal shock conditions

    International Nuclear Information System (INIS)

    Integrity evaluation methods for nuclear Reactor Pressure Vessels (RPVs) under Pressurised Thermal Shock (PTS) loading are applied by French Utility. They are based on the analysis of the behaviour of relatively shallow cracks under PTS loading conditions due to the emergency cooling during SBLOCA transients. This paper explains the Research and Development program started at E.D.F about the cooling phenomena of a PWR vessel after a Pressurised Thermal Shock. The numerical results are obtained with the EDF Thermal Hydraulic code (CodeSaturne) coupled with the thermal-solid code SYRTHES to take into account the conjugate heat transfer on the cooling of the vessel. We first explain the numerical program concerning the qualification task of this CFD-Tool for Safety Injection studies. We have investigated several configurations. Two experiment test cases have been studied and we present a comparison between experimental and numerical results in terms of temperature field in cold leg but also in a down comer. Then, for the Thermal-Hydraulic reactor study, the geometries used represent a three and a four loop PWR. In these calculations, the simulated mesh takes into account as much as possible of the exact geometry of the lower plenum. Numerical results are given in terms of temperature field in the cold legs and in the down comer, as well as in the solid part formed by cladding and base metal. On the whole, the main purpose of the numerical thermalhydraulic studose of the numerical thermalhydraulic studies is to accurately estimate the distribution of fluid temperature in the down comer and the heat transfer coefficients on the inner RPV surface for a fracture mechanics computation which will subsequently assess the associated RPV safety margins. Lastly, a parametric study has been carried out in order to assess the relative importance or influence of some physical data. Two cases are suited. The first part of this paper reports the effects of the thermal coupling between the RPV and the fluid flow. To this end, two computations have been realised the first one taking account of the thermal coupling, the other one neglecting the thermal feedback of the wall to the fluid during the transient. In the second study, the safety injection temperature is increased from the usual value of 9 degree C in the previous calculations up to 35 degree C. (authors)

  7. Pressure conditions in WWER-440 primary circuit during transients due to positive reactivity changes

    International Nuclear Information System (INIS)

    Calculations were performed of pressure variations in the primary circuit and in the pressurizer for processes such as regulating rod ejection or uncontrolled sliding-out of a group of regulating rods. The effect of the pressurizer on the time behavior of pressure in the said transients is shown graphically. The possibility is also shown of simple approximative determination of pressure values for the primary circuit-pressurizer system as a whole. (author)

  8. High-pressure phase transitions in BiFeO3: hydrostatic vs. non-hydrostatic conditions

    OpenAIRE

    Guennou, Mael; Bouvier, Pierre; Haumont, Raphae?l; Garbarino, Gaston; Kreisel, Jens

    2011-01-01

    We report high-pressure x-ray diffraction experiments on BiFeO3 (BFO) single crystals in diamond-anvil cells up to 14 GPa. Two data sets are compared, one in hydrostatic conditions, with helium used as pressure-transmitting medium, and the other in non-hydrostatic conditions, with silicon oil as pressure-transmitting medium. It is shown that the crystal undergoes different phase transitions in the two cases, highlighting the high sensitivity of BFO to non-hydrostatic stress....

  9. Temperature and pressure characteristics of JAPM dosimeter and long-term stability of several barometers

    International Nuclear Information System (INIS)

    An ionization chamber is one of the most suitable devices to dose determinations for any types of ionizing radiations. It is necessary, however, to correct for air density within the chamber due to difference of an ambient temperature and pressure from the standard conditions for them. There are few data about time constants of temperature and pressure for an ionization chamber, while Lowry was pointed out of the influence for a Farmer chamber in a special case. We have been measured time constants of temperature and pressure for JAPM chamber using a miniature thermister and a special pressure gauge which both can be expressed with digital quantity. Measurements of temperature characteristics were made for four conditions as follows; (a) chamber with build up cap in air, (b) chamber in air, (c) chamber in checking source, and (d) chamber in a Mix-DP phantom. The results show that the times required to attain to room temperature within 0.3 degrees of centigrade for conditions (a) through (d), proviede that the initial temperature difference between the chamber and room is supposed to be 3 degrees of centigrades, are 17, 9, 7 and 5 minutes, respectively. The pressure time constant is less than 10 seconds. To determine the barometric pressure within the accuracy of 0.1 percent using Aneroid barometer, only a precission type of the barometer is nece ssary. (author)

  10. QUAVER - A programme to evaluate monopole and dipole boundary conditions in pressure tube reactor lattices

    International Nuclear Information System (INIS)

    In order to apply source-sink theory to pressure tube reactor lattices it is necessary to calculate boundary conditions at the fuel channel/moderator interfaces to be satisfied by the neutron flux. A method is described for evaluating the necessary coefficients using multi-group diffusion theory in a cylindricalised lattice cell for both monopole and dipole components of flux. Provision is made for in or out leakage of neutrons in each group at the cell boundary so that allowance can be made for effects of cell environment on the channel boundary conditions. The programme QUAVER (written in EGTRAN) is described for use on the English Electric KDF9 Computer. QUAVER outputs the boundary condition matrices on cards for use in source-sink core calculations, and includes a facility for the condensation of the primary group output to a secondary group structure. The numerical method and the data input specification are described together with full details of a sample calculation. (author)

  11. Small Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

    Science.gov (United States)

    Broerman, Craig; Sweterlitsch, Jeffrey

    2011-01-01

    A principle concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has long been evaluated for use in this application and several programs are evaluating it for use in both a cabin as well as space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of small scale SA9T testing that was performed over a variety of test conditions and with a variety of trace contaminants. Testing evaluated the ability of SA9T media to sufficiently remove CO2 and H2O after exposure to a fully saturated trace contaminant at ambient conditions. Testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures during cyclic operation with a constant inlet contaminant load. In addition, testing evaluated the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream.

  12. Bench-Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

    Science.gov (United States)

    Broerman, Craig; Sweterlitsch, Jeff

    2011-01-01

    A principal concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has been evaluated for use in this application and several programs are evaluating it for use in both cabin and space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of bench-scale SA9T testing that was performed under a variety of test conditions and with several different trace contaminants. Tests were conducted to determine if the capacity of the SA9T media to sufficiently remove CO2 and H2O is compromised after exposure to a fully saturated trace contaminant at ambient conditions. Tests also were conducted to evaluate the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream. In addition, testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures (29.6 KPa/4.3 psia) during cyclic operation with a constant inlet contaminant load.

  13. HEADCO: a program for converting observed water levels and pressure measurements to formation pressure and standard hydraulic head

    International Nuclear Information System (INIS)

    Static water-level and fluid pressure measurements are commonly converted in hydrologic studies to formation pressure and hydraulic head, which are used to determine groundwater flow characteristics of aquifer systems. While the direct use of field measurements is usually adequate for determining formation pressure and hydraulic head for shallow flow systems (i.e., <1000 ft), corrections and conversion parameters must be used to properly account for fluid-column density effects, which commonly occur with deep systems. This report presents a program, HEADCO, for converting static water-level and pressure measurements to formation pressure and standard hydraulic head. The HEADCO program corrects field measurements for the effects of fluid-density variation and selected external stresses. Factors that affect density of the fluid column, in which field measurements are made, include temperature, pressure, salinity, suspended solids, and multiphase conditions. External stresses examined in HEADCO include barometric and earth tide fluctuations, and gravitational acceleration variation. A program description and procedures for converting field measurements obtained using field test arrangements commonly employed in the Basalt Waste Isolation Project field program are provided in this report. The report includes user instructions and an illustrative test example. Results of a field example comparison are also provided. This comparison examines observed and HEADCO-calculated p examines observed and HEADCO-calculated pressures for 30 pressure probes recently calibrated in a laboratory and tested under field conditions at borehole DC-8. The test case and field example comparisons indicate that HEADCO provides accurate estimates of formation pressure and standard hydraulic head that are well within the accuracy range of downhole pressure-measuring instrumentation. 44 refs., 14 figs., 8 tabs

  14. Micromechanical cohesion force between gas hydrate particles measured under high pressure and low temperature conditions.

    Science.gov (United States)

    Lee, Bo Ram; Sum, Amadeu K

    2015-04-01

    To prevent hydrate plugging conditions in the transportation of oil/gas in multiphase flowlines, one of the key processes to control is the agglomeration/deposition of hydrate particles, which are determined by the cohesive/adhesive forces. Previous studies reporting measurements of the cohesive/adhesive force between hydrate particles used cyclopentane hydrate particles in a low-pressure micromechanical force apparatus. In this study, we report the cohesive forces of particles measured in a new high-pressure micromechanical force (MMF) apparatus for ice particles, mixed (methane/ethane, 74.7:25.3) hydrate particles (Structure II), and carbon dioxide hydrate particles (Structure I). The cohesive forces are measured as a function of the contact time, contact force, temperature, and pressure, and determined from pull-off measurements. For the measurements performed of the gas hydrate particles in the gas phase, the determined cohesive force is about 30-35 mN/m, about 8 times higher than the cohesive force of CyC5 hydrates in the liquid CyC5, which is about 4.3 mN/m. We show from our results that the hydrate structure (sI with CO2 hydrates and sII with CH4/C2H6 hydrates) has no influence on the cohesive force. These results are important in the deposition of a gas-dominated system, where the hydrate particles formed in the liquid phase can then stick to the hydrate deposited in the wall exposed to the gas phase. PMID:25785915

  15. Assessment of the Swelling Pressure of the Green Clay of Tangier (Morocco Compared with the Soil-Moisture Conditions

    Directory of Open Access Journals (Sweden)

    El Bahlouli Tarik

    2014-04-01

    Full Text Available The swelling phenomenon appears seriously when changing the soil-moisture conditions. The swelling pressure induced by the expansive soil can causes unfavourable problems or instability for the civil structures. So, understanding the soil behavior is considered a valuable work for engineers and consultants in the geotechnical and civil engineering sectors. In reality, the assessment of the swelling pressure of expansive soil depends, first of all, of test conditions related to the change of soil-moisture, as it happens, the influence of the combination “loading-start wetting” and also the unloading process after saturation. To this end, we establish an experimental study on the green clay of Tangier to evaluate the swelling pressure by using oedometer apparatus. Secondly, attention is bore to the combination “initial water content-dry density”, another factor related to the change of the soil-moisture, to show the influence of initial state condition on the swelling pressure.

  16. Effect of Nb additions on the microstructure, thermal stability and mechanical behavior of high pressure Zr phases under ambient conditions

    International Nuclear Information System (INIS)

    Research highlights: ? We analyze the influence of Nb additions on the shear-induced ? ? ? ? ? phase transformations in pure Zr by high pressure torsion (HPT). ? Nb reduces the transition pressures and increases the transformation kinetics. ? High pressure phases are retained under ambient conditions due to the presence of an internal stress. ? Post-HPT annealing allows to fabricate bimodal/biphase nanostructures with enhanced mechanical behavior. - Abstract: This paper analyzes the influence of Nb on the shear-induced ? ? ? ? ? transformation taking place when processing Zr by high pressure torsion (HPT) under suitable conditions of pressure and shear. With that purpose, pure Zr and Zr-2.5%Nb were processed by HPT at room temperature and at pressures ranging from 0.25 to 6 GPa using 5 anvil turns. Nb causes a further reduction of the transition pressures, which are already lower when applying shear besides pressure. Thus, the transition pressure to the ? phase is reduced at least 100 times in the Zr-Nb alloy. Alloying with Nb decreases the grain size of the transformed phases, significantly enhances their thermal stability and increases their UTS and elongation to failure. Selected post-HPT annealing treatments lead to the development of very tough, multiphase Zr and Zr-Nb with bimodal grain size distributions. The retention of the high pressure phases under ambient conditions is explained by the development of a high internal stress during prol stress during processing. This stress is measured by synchrotron radiation diffraction at HZB-BESSY II. It is proposed that the presence of Nb reduces the internal stress level required for the retention of the high pressure phases.

  17. Effect of Nb additions on the microstructure, thermal stability and mechanical behavior of high pressure Zr phases under ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhilyaev, A.P. [Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, 28040 Madrid (Spain); Institute for Metals Superplasticity Problems, RAS, 450001 Ufa (Russian Federation); Sabirov, I. [Madrid Institute for Advanced Studies of Materials (IMDEA-Materials Institute) C/Profesor Aranguren s/n, 28040 Madrid (Spain); Gonzalez-Doncel, G. [Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, 28040 Madrid (Spain); Molina-Aldareguia, J.; Srinivasarao, B. [Madrid Institute for Advanced Studies of Materials (IMDEA-Materials Institute) C/Profesor Aranguren s/n, 28040 Madrid (Spain); Perez-Prado, M.T., E-mail: teresa.perez.prado@imdea.org [Madrid Institute for Advanced Studies of Materials (IMDEA-Materials Institute) C/Profesor Aranguren s/n, 28040 Madrid (Spain)

    2011-04-15

    Research highlights: {yields} We analyze the influence of Nb additions on the shear-induced {alpha} {yields} {omega} {yields} {beta} phase transformations in pure Zr by high pressure torsion (HPT). {yields} Nb reduces the transition pressures and increases the transformation kinetics. {yields} High pressure phases are retained under ambient conditions due to the presence of an internal stress. {yields} Post-HPT annealing allows to fabricate bimodal/biphase nanostructures with enhanced mechanical behavior. - Abstract: This paper analyzes the influence of Nb on the shear-induced {alpha} {yields} {omega} {yields} {beta} transformation taking place when processing Zr by high pressure torsion (HPT) under suitable conditions of pressure and shear. With that purpose, pure Zr and Zr-2.5%Nb were processed by HPT at room temperature and at pressures ranging from 0.25 to 6 GPa using 5 anvil turns. Nb causes a further reduction of the transition pressures, which are already lower when applying shear besides pressure. Thus, the transition pressure to the {beta} phase is reduced at least 100 times in the Zr-Nb alloy. Alloying with Nb decreases the grain size of the transformed phases, significantly enhances their thermal stability and increases their UTS and elongation to failure. Selected post-HPT annealing treatments lead to the development of very tough, multiphase Zr and Zr-Nb with bimodal grain size distributions. The retention of the high pressure phases under ambient conditions is explained by the development of a high internal stress during processing. This stress is measured by synchrotron radiation diffraction at HZB-BESSY II. It is proposed that the presence of Nb reduces the internal stress level required for the retention of the high pressure phases.

  18. Ultrasound propagation in air-filled cylindrical pores under pressurized conditions

    Science.gov (United States)

    Gómez Álvarez-Arenas, T. E.; Acosta, V.; Apel, P. Yu.; Orelovitch, O. L.

    2012-05-01

    Ion-track membranes (ITM) are known as polymer films with straight pore channels the size, shape, orientation and density of which can be precisely controlled. Previous ultrasonic studies of ITM using air-coupled and wide-band ultrasound pulses (0.1-5.0 MHz) revealed the possibility to isolate and study ultrasound propagation in these pores. Hence a novel ultrasonic technique has been established to determine pore characteristics of ITM using this pore propagation mode. In this work, we present a modification of the technique based on the use of pressurized air. This is achieved by enclosing transducers and samples in a pressurized chamber (1-9 bar). The main objective of this study is to reduce the attenuation of the ultrasound waves propagating in the pores and to increase the coupling of the ultrasonic energy into this pore propagation mode at the membrane surface in order to extend the applicability range of the existing technique to the characterization of ITM with small pores (diameter air-coupled ultrasound at room conditions may present some drawbacks.

  19. An attempt to prepare carbon clathrate compounds using high-pressure and high-temperature conditions

    International Nuclear Information System (INIS)

    In an attempt to prepare a crystalline carbon compound having a three-dimensional (3D) network similar to silicon clathrate superconductors, fullerene C60 molecules were three-dimensionally polymerized using high-pressure and high-temperature conditions. A single crystal of 3D polymer was obtained from a two-dimensional C60 polymer with a body-centered orthorhombic symmetry. The X-ray structural analysis of the 3D polymer revealed that the spherical C60 monomer molecules were substantially deformed to cuboidal shapes, each unit being bonded to eight neighboring units to form a body-centered orthorhombic lattice. The new 3D polymer was electrically conductive and showed high micro-Vickers hardness comparable to that of cubic BN

  20. Airblast atomization of alternative liquid petroleum fuels under high pressure conditions

    Science.gov (United States)

    Jasuja, A. K.

    1981-07-01

    A study has been conducted of the effects that fuel and air properties have upon the mean droplet size characteristics of a pre-filming airblast atomizer of the type commonly employed in the gas turbine engine. The fuels tested included kerosine, gas oil and two blends of gas oil in residual fuel oil. The tests were carried out over a wide range of air pressures (about 1 to 13 atmospheres), fuel viscosities (about 0.001 to 0.037 Ns/sq m) and the spray mean drop sizes were measured using a laser light-scattering technique. The experimental data accumulated in the study is presented in the paper and it is concluded that the spray Sauter Mean Diameter performance of the atomizer studied can be predicted to a reasonable degree of accuracy, over the range of conditions studied, by a relatively simple correlating equation.

  1. Evaluation of pressure boundary conditions for permeability calculations using the lattice-Boltzmann method

    CERN Document Server

    Narváez, Ariel

    2010-01-01

    Lattice-Boltzmann (LB) simulations are a common tool to numerically estimate the permeability of porous media. For valuable results, the porous structure has to be well resolved resulting in a large computational effort as well as high memory demands. In order to estimate the permeability of realistic samples, it is of importance to not only implement very efficient codes, but also to choose the most appropriate simulation setup to achieve accurate results. With the focus on accuracy and computational effort, we present a comparison between different methods to apply an effective pressure gradient, efficient boundary conditions, as well as two LB implementations based on pore-matrix and pore-list data structures.

  2. Investigation of LPP combustors under elevated pressure conditions; Untersuchungen zu LPP-Flugtriebwerksbrennkammern unter erhoehtem Druck

    Energy Technology Data Exchange (ETDEWEB)

    Fink, R.

    2001-05-01

    The development of new combustor concepts for aero engines to meet future emissions regulations in based on a detailed knowledge of the combustion process and the velocity field. In the presented thesis, non intrusive measurements were performed in a model combustion chamber under almost realistic pressure and temperature conditions. The species OH, NO, unburned hydrocarbons and fuel droplets were detected in 2 dimensions with the Laser Induced Fluorescence (LIF). The velocity field was measured with the Particle Image Velocimetry technique (PIV). [German] Die Weiterentwicklung neuer Brennkammerkonzepte zur Erfuellung zukuenftiger Schadstoffemissionsrichtlinien erfordert genaue Kenntnisse der ablaufenden Verbrennungs- und Stroemungsvorgaenge in der Brennkammer. Bei den in der Arbeit vorgestellten Untersuchungen wurden in einer LPP-Modellbrennkammer unter annaehernd realistischen Eintrittsbedingungen die Spezies OH, NO, unverbrannte Kohlenwasserstoffe sowie noch fluessiger Brennstoff zweidimensional anhand der Laserinduzierten Fluoreszenz (LIF) nachgewiesen. Das Stroemungsfeld wurde mit Hilfe der Particle Image Velocimetry (PIV) gemessen.

  3. Intraocular pressure vs intracranial pressure in disease conditions: A prospective cohort study (Beijing iCOP study

    Directory of Open Access Journals (Sweden)

    Li Zhen

    2012-08-01

    Full Text Available Abstract Background The correlation between intracranial pressure (ICP and intraocular pressure (IOP is still controversial in literature and hence whether IOP can be used as a non-invasive surrogate of ICP remains unknown. The aim of the current study was to further clarify the potential correlation between ICP and IOP. Methods The IOP measured with Goldmann applanation tonometer was carried out on 130 patients whose ICP was determined via lumber puncture. The Pearson correlation coefficient between ICP and IOP was calculated, the fisher line discriminated analysis to evaluate the effectivity of using IOP to predict the ICP level. Results A significant correlation between ICP and IOP was found. ICP was correlated significantly with IOP of the right eyes (p? Conclusion Our data suggested that although a significant correlation exists between ICP and IOP, caution needs to be taken when using IOP readings by Goldmann applanation tonometer as a surrogate for direct cerebrospinal fluid pressure measurement of ICP.

  4. Theoretical and numerical investigations of TAP experiments. New approaches for variable pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Senechal, U.; Breitkopf, C. [Technische Univ. Dresden (Germany). Inst. fuer Energietechnik

    2011-07-01

    Temporal analysis of products (TAP) is a valuable tool for characterization of porous catalytic structures. Established TAP-modeling requires a spatially constant diffusion coefficient and neglect convective flows, which is only valid in Knudsen diffusion regime. Therefore in experiments, the number of molecules per pulse must be chosen accordingly. New approaches for variable process conditions are highly required. Thus, a new theoretical model is developed for estimating the number of molecules per pulse to meet these requirements under any conditions and at any time. The void volume is calculated as the biggest sphere fitting between three pellets. The total number of pulsed molecules is assumed to fill the first void volume at the inlet immediately. Molecule numbers from these calculations can be understood as maximum possible molecules at any time in the reactor to be in Knudsen diffusion regime, i.e., above the Knudsen number of 2. Moreover, a new methodology for generating a full three-dimensional geometrical representation of beds is presented and used for numerical simulations to investigate spatial effects. Based on a freely available open-source game physics engine library (BULLET), beds of arbitrary-sized pellets can be generated and transformed to CFD-usable geometry. In CFD-software (ANSYS CFX registered) a transient diffusive transport equation with time-dependent inlet boundary conditions is solved. Three different pellet diameters were investigated with 1e18 molecules per pulse, which is higher than the limit from the theoretical calculation. Spatial and temporal distributions of transported species show regions inside the reactor, where non-Knudsen conditions exist. From this results, the distance from inlet can be calculated where the theoretical pressure limit (Knudsen number equals 2) is obtained, i.e., from this point to the end of the reactor Knudsen regime can be assumed. Due to linear dependency of pressure and concentration (assuming ideal gas thermodynamics), the results from one numerical simulation can be converted to any number of molecules per pulse. With this procedure, the distance from inlet from which on Knudsen regime can be assumed for different molecules per pulse can be calculated easily. The new model will be applied to enhance the description of industrially relevant conversions, as for instance alkane conversions on transition metal oxides. (orig.)

  5. An experimental study on sub-cooled flow boiling CHF of R134a at low pressure condition with Atmospheric Pressure (AP) Plasma assisted surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Seung-Jun Kim; Ling Zou; Barclay G. Jones

    2015-02-01

    In this study, sub-cooled flow boiling critical heat flux tests at low pressure were conducted in a rectangular flow channel with one uniformly heated surface, using simulant fluid R-134a as coolant. The experiments were conducted under the following conditions: (1) inlet pressure (P) of 400 ~ 800 kPa, (2) mass flux (G) of 124 ~ 248 kg/m2·s, (3) inlet sub-cooling enthalpy (??!) of 12~ 26 kJ/kg. Parametric trends of macroscopic system parameters (G, P, ??!) were examined by changing inlet conditions. Those trends were found to be generally consistent with previous understandings of CHF behavior at low pressure condition (i.e. reduced pressure less than 0.2). A fluid-to-fluid scaling model was utilized to convert the test data obtained with the simulant fluid (R-134a) into the prototypical fluid (water). The comparison between the converted CHF of equivalent water and CHF look-up table with same operation conditions were conducted, which showed good agreement. Furthermore, the effect of surface wettability on CHF was also investigated by applying atmospheric pressure plasma (AP-Plasma) treatment to modify the surface characteristic. With AP-Plasma treatment, the change of microscopic surface characteristic was measured in terms of static contact angle. The static contact angle was reduced from 80° on original non-treated surface to 15° on treated surface. An enhancement of 18% on CHF values under flow boiling conditions were observed on AP-Plasma treated surfaces compared to those on non-treated heating surfaces.

  6. Appropriate welding conditions of temper bead weld repair for SQV2A pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, R.; Matsuda, F. [NDE Center, Japan Power Engineering and Inspection Corp. (Japan); Brziak, P. [Welding Research Inst. - Industrial Inst. of Slovak Republic (Slovakia); Lomozik, M. [Inst. of Welding (Poland)

    2004-07-01

    Temper bead welding technique is one of the most important repair welding methods for large structures for which it is difficult to perform the specified post weld heat treatment. In this study, appropriate temper bead welding conditions to improve the characteristics of heat affected zone (HAZ) are studied using pressure vessel steel SQV2A corresponding to ASTM A533 Type B Class 1. Thermal/mechanical simulator is employed to give specimens welding thermal cycles from single to quadruple cycle. Charpy absorbed energy and hardness of simulated CGHAZ by first cycle were degraded as compared with base metal. Improvability of these degradations by subsequent cycles is discussed and appropriate temper bead thermal cycles are clarified. When the peak temperature lower than Ac1 and near Ac1 in the second thermal cycle is applied to CGAHZ by first thermal cycle, the characteristics of CGHAZ improve enough. When the other peak temperatures (that is, higher than Ac1) in the second thermal cycle are applied to the CGHAZ, third or more thermal cycle temper bead process should be applied to improve the properties. Appropriate weld condition ranges are selected based on the above results. The validity of the selected ranges is verified by the temper bead welding test. (orig.)

  7. Characteristics of Syngas Auto-ignition at High Pressure and Low Temperature Conditions with Thermal Inhomogeneities

    KAUST Repository

    Pal, Pinaki

    2015-05-31

    Effects of thermal inhomogeneities on syngas auto-ignition at high-pressure low-temperature conditions, relevant to gas turbine operation, are investigated using detailed one-dimensional numerical simulations. Parametric tests are carried out for a range of thermodynamic conditions (T = 890-1100 K, P = 3-20 atm) and composition (? = 0.1, 0.5). Effects of global thermal gradients and localized thermal hot spots are studied. In the presence of a thermal gradient, the propagating reaction front transitions from spontaneous ignition to deflagration mode as the initial mean temperature decreases. The critical mean temperature separating the two distinct auto-ignition modes is computed using a predictive criterion and found to be consistent with front speed and Damkohler number analyses. The hot spot study reveals that compression heating of end-gas mixture by the propagating front is more pronounced at lower mean temperatures, significantly advancing the ignition delay. Moreover, the compression heating effect is dependent on the domain size.

  8. Appropriate welding conditions of temper bead weld repair for SQV2A pressure vessel steel

    International Nuclear Information System (INIS)

    Temper bead welding technique is one of the most important repair welding methods for large structures for which it is difficult to perform the specified post weld heat treatment. In this study, appropriate temper bead welding conditions to improve the characteristics of heat affected zone (HAZ) are studied using pressure vessel steel SQV2A corresponding to ASTM A533 Type B Class 1. Thermal/mechanical simulator is employed to give specimens welding thermal cycles from single to quadruple cycle. Charpy absorbed energy and hardness of simulated CGHAZ by first cycle were degraded as compared with base metal. Improvability of these degradations by subsequent cycles is discussed and appropriate temper bead thermal cycles are clarified. When the peak temperature lower than Ac1 and near Ac1 in the second thermal cycle is applied to CGAHZ by first thermal cycle, the characteristics of CGHAZ improve enough. When the other peak temperatures (that is, higher than Ac1) in the second thermal cycle are applied to the CGHAZ, third or more thermal cycle temper bead process should be applied to improve the properties. Appropriate weld condition ranges are selected based on the above results. The validity of the selected ranges is verified by the temper bead welding test. (orig.)

  9. Comparison Of Vented And Absolute Pressure Transducers For Water-Level Monitoring In Hanford Site Central Plateau Wells

    International Nuclear Information System (INIS)

    Automated water-level data collected using vented pressure transducers deployed in Hanford Site Central Plateau wells commonly display more variability than manual tape measurements in response to barometric pressure fluctuations. To explain this difference, it was hypothesized that vented pressure transducers installed in some wells are subject to barometric pressure effects that reduce water-level measurement accuracy. Vented pressure transducers use a vent tube, which is open to the atmosphere at land surface, to supply air pressure to the transducer housing for barometric compensation so the transducer measurements will represent only the water pressure. When using vented transducers, the assumption is made that the air pressure between land surface and the well bore is in equilibrium. By comparison, absolute pressure transducers directly measure the air pressure within the wellbore. Barometric compensation is achieved by subtracting the well bore air pressure measurement from the total pressure measured by a second transducer submerged in the water. Thus, no assumption of air pressure equilibrium is needed. In this study, water-level measurements were collected from the same Central Plateau wells using both vented and absolute pressure transducers to evaluate the different methods of barometric compensation. Manual tape measurements were also collected to evaluate the transducers. Measurements collected during this study demonstrated that the vented pressure transducers over-responded to barometric pressure fluctuations due to a pressure disequilibrium between the air within the wellbores and the atmosphere at land surface. The disequilibrium is thought to be caused by the relatively long time required for barometric pressure changes to equilibrate between land surface and the deep vadose zone and may be exacerbated by the restriction of air flow between the well bore and the atmosphere due to the presence of sample pump landing plates and well caps. The disequilibrium is likely limited to wells screened across the water table (i.e., open to the deep vadose zone) where the depth to water is large or a low-permeability layer occurs in the vadose zone. Such wells are a pathway for air movement between the deep vadose zone and land surface and this sustains the pressure disequilibrium between the well bore and the atmosphere for longer time periods. Barometric over-response was not observed with the absolute pressure transducers because barometric compensation was achieved by directly measuring the air pressure within the well. Users of vented pressure transducers should be aware of the over-response issue in certain Hanford Site wells and ascertain if it will affect the use of the data. Pressure disequilibrium between the well and the atmosphere can be identified by substantial air movement through the wellbore. In wells exhibiting pressure disequilibrium, it is recommended that absolute pressure transducers be used rather than vented transducers for applications that require precise automated determinations of well water-level changes in response to barometric pressure fluctuations.

  10. Magnetite reactivity in representative conditions of the secondary circuit of pressurized water reactors

    International Nuclear Information System (INIS)

    In the secondary circuit of Pressurized Water Reactors (PWR), magnetite deposits lead to steam generators (SG) fouling, which decreases thermal performances and enhances stress corrosion cracking (SCC). The aim of this study is to improve the understanding of magnetite particles behaviour and their reactivity in the secondary circuit conditions. Experimental tests investigated the fast thermal decomposition of hydrazine, injected in the secondary circuit to eliminate oxygen. Temperature, pH, and catalytic properties of materials surfaces have an influence on the kinetics of hydrazine decomposition. A predictive model was proposed. Growing, transport and deposits of iron oxides, essentially formed with magnetite, responsible of the steam generator fouling, were studied in the experimental loop FORTRAND, Formation and Transport of Deposits. Surface characterizations show that magnetite is the corrosion product formed on carbon steel and stainless steel at 220 C, and goethite is formed at room temperature on stainless steel. Results indicate also that the effect of different amines, used in the secondary circuit, on the soluble iron is principally due to their effect on the pH. Performed tests highlight transport and deposition of magnetite particles in the loop. Deposits formed in the SG could promote SCC of tubes by sorption and reduction of sulfates. To reproduce secondary circuit conditions, studies of sorption were made in reducing medium imposed by hydrazine. At 275 C, the presence of hydrazine has an effect on the speciation of sulfates in solution but does not seem to influence the sorption nor to lead to H2S(g) emission predicted by thermodynamic calculations. These experimental results are used to predict sulfur and iron species behaviour in the secondary circuit. Low pH conditioning enhances soluble iron concentration, consequently iron transport in the SG. Sulfides are the most probable sulfur species in flow-restricted areas of SG, harmful for stress corrosion cracking. (author)

  11. Conditionally Increased Acoustic Pressures in Nonfetal Diagnostic Ultrasound Examinations Without Contrast Agents: A Preliminary Assessment.

    Science.gov (United States)

    Nightingale, Kathryn R; Church, Charles C; Harris, Gerald; Wear, Keith A; Bailey, Michael R; Carson, Paul L; Jiang, Hui; Sandstrom, Kurt L; Szabo, Thomas L; Ziskin, Marvin C

    2015-07-01

    The mechanical index (MI) has been used by the US Food and Drug Administration (FDA) since 1992 for regulatory decisions regarding the acoustic output of diagnostic ultrasound equipment. Its formula is based on predictions of acoustic cavitation under specific conditions. Since its implementation over 2 decades ago, new imaging modes have been developed that employ unique beam sequences exploiting higher-order acoustic phenomena, and, concurrently, studies of the bioeffects of ultrasound under a range of imaging scenarios have been conducted. In 2012, the American Institute of Ultrasound in Medicine Technical Standards Committee convened a working group of its Output Standards Subcommittee to examine and report on the potential risks and benefits of the use of conditionally increased acoustic pressures (CIP) under specific diagnostic imaging scenarios. The term "conditionally" is included to indicate that CIP would be considered on a per-patient basis for the duration required to obtain the necessary diagnostic information. This document is a result of that effort. In summary, a fundamental assumption in the MI calculation is the presence of a preexisting gas body. For tissues not known to contain preexisting gas bodies, based on theoretical predications and experimentally reported cavitation thresholds, we find this assumption to be invalid. We thus conclude that exceeding the recommended maximum MI level given in the FDA guidance could be warranted without concern for increased risk of cavitation in these tissues. However, there is limited literature assessing the potential clinical benefit of exceeding the MI guidelines in these tissues. The report proposes a 3-tiered approach for CIP that follows the model for employing elevated output in magnetic resonance imaging and concludes with summary recommendations to facilitate Institutional Review Board (IRB)-monitored clinical studies investigating CIP in specific tissues. PMID:26112617

  12. Methods for quantifying the influences of pressure and temperature variation on metal hydride reaction rates measured under isochoric conditions

    Science.gov (United States)

    Voskuilen, Tyler G.; Pourpoint, Timothée L.

    2013-11-01

    Analysis techniques for determining gas-solid reaction rates from gas sorption measurements obtained under non-constant pressure and temperature conditions often neglect temporal variations in these quantities. Depending on the materials in question, this can lead to significant variations in the measured reaction rates. In this work, we present two new analysis techniques for comparison between various kinetic models and isochoric gas measurement data obtained under varying temperature and pressure conditions in a high pressure Sievert system. We introduce the integral pressure dependence method and the temperature dependence factor as means of correcting for experimental variations, improving model-measurement fidelity, and quantifying the effect that such variations can have on measured reaction rates. We use measurements of hydrogen absorption in LaNi5 and TiCrMn to demonstrate the effect of each of these methods and show that their use can provide quantitative improvements in interpretation of kinetics measurements.

  13. EXAFS and Raman studies of mechanical alloyed Ni25Se75 mixture under high-pressure conditions

    International Nuclear Information System (INIS)

    Extended X-ray Absorption Fine Structure and Raman studies were performed to follow the structural and vibrational behavior of a mechanical alloyed Ni25Se75 mixture, containing nanocrystalline pyrite NiSe2 phase, when exposed to high-pressure conditions. An increase in the local structural order of the nanocrystalline phase with pressure increasing was observed by means of Debye-Waller factor analysis. The relative Ni nearest-neighbors distances were determined as a function of pressure, which were used to determine the inverse linear compressibility of the nanocrystalline pyrite NiSe2 alloy as well as its derivate by means of Murnaghan's equation. The Raman results showed tentative NiSe2 phonons dispersion with pressure that becomes a difficult task since the existence/photo-induced nucleation of an important amount of nanocrystalline Se, detected due to the observation of its pressure-induced phase transitions

  14. Measurement of subcooled boiling pressure drop and local heat transfer coefficient in horizontal tube under LPLF conditions

    International Nuclear Information System (INIS)

    Highlights: ? Measured subcooled boiling pressure drop and local heat transfer coefficient in horizontal tubes. ? Infra-red thermal imaging is used for wall temperature measurement. ? Developed correlations for pressure drop and local heat transfer coefficient. -- Abstract: Horizontal flow is commonly encountered in boiler tubes, refrigerating equipments and nuclear reactor fuel channels of pressurized heavy water reactors (PHWR). Study of horizontal flow under low pressure and low flow (LPLF) conditions is important in understanding the nuclear core behavior during situations like LOCA (loss of coolant accidents). In the present work, local heat transfer coefficient and pressure drop are measured in a horizontal tube under LPLF conditions of subcooled boiling. Geometrical parameters covered in this study are diameter (5.5 mm, 7.5 mm and 9.5 mm) and length (550 mm, 750 mm and 1000 mm). The operating parameters varied are mass flux (450–935 kg/m2 s) and inlet subcooling (29 °C, 50 °C and 70 °C). Infra-red thermography is used for the measurement of local wall temperature to estimate the heat transfer coefficient in single phase and two phase flows with water as the working medium at atmospheric pressure. Correlation for single phase diabatic pressure drop ratio (diabatic to adiabatic) as a function of viscosity ratio (wall temperature to fluid temperature) is presented. Correlation for pressure drop under subcooled boiling conditions as a function of Boiling number (Bo) and Jakob number (Ja) is obtained. Correlation for single phase heat transfer coefficient in the thermal developing region is presented as a function of Reynolds number (Re), Prandtl number (Pr) and z/d (ratio of axial length of the test section to diameter). Correlation for two phase heat transfer coefficient under subcooled boiling condition is developed as a function of boiling number (Bo), Jakob number (Ja) and Prandtl number (Pr)

  15. Effect of Shear Deformation and Relaxation of Support Conditions on Buckling of Pressurized Pipelines containing Expansion Bellows

    CERN Document Server

    Skoczen, Blazej

    1998-01-01

    Mechanical stability of pressurized expansion bellows and tube-bellows-tube interconnects is considered.Effect of shear deformation on buckling pressure of bellows is shown y using Engesser's model. A generalized equivalent column concept is developed in order to study the effect of relaxation of support conditions on stability of interconnects containing expansion bellows. Two general modes of buckling are discussed: column instability of well-supported bellows (I) and buckling of tube-bellows--tube interconnect if the support-bellows distances are large enough (II). A dramatic drop of critical pressure in the transition region from mode I to mode II is shown.

  16. Comparison of Irradiation Conditions of VVER-1000 Reactor Pressure Vessel and Surveillance Specimens for Various Core Loadings

    Science.gov (United States)

    Bukanov, V. N.; Diemokhin, V. L.; Grytsenko, O. V.; Vasylieva, O. G.; Pugach, S. M.

    2009-08-01

    The comparative analysis of irradiation conditions of surveillance specimens and pressure vessel of VVER-1000 reactor has been carried out for various configurations of the core. It is proved the fluences onto specimens and a pressure vessel don't correlate with each other but only the spectral indexes do. It is revealed that in the case of the specimen reconstitution technique application the data on the assembly orientation to the reactor core is sufficient to complete four representative groups from the samples of any container assembly. It is shown that the standard surveillance program of VVER-1000 allows obtaining reliable information on the reactor pressure vessel state.

  17. The Design Features of the High- and Intermediate-Pressure Cylinders with Forced Cooling for Turbines for Ultrasupercritical Steam Conditions

    Science.gov (United States)

    Petrenya, Yu. K.; Khomenok, L. A.; Pichugin, I. I.; Vladimirskii, O. A.; Lyapunov, V. M.; Lisyanskii, A. S.; Kachuriner, Yu. Ya.; Ignat'eva, T. A.; Ivanov, S. A.

    2008-01-01

    The systems for forced steam cooling of the high-pressure rotor and stator and the intermediate-pressure rotor of a steam turbine for ultrasupercritical steam conditions developed at the Central Boiler-Turbine Institute Research and Production Association jointly with Leningrad Metal Works (a branch of OAO Silovye Mashiny) are considered. The results from calculations of the thermally stressed state of the cooled elements of the high- and intermediate-pressure cylinders have shown that the design solutions adopted for forced cooling of these elements are efficient and promising.

  18. On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions

    Science.gov (United States)

    Schobeiri, Meinhard T.; Ozturk, Burak; Ashpis, David E.

    2005-01-01

    The present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding the physics of the separation phenomenon under periodic unsteady wake flow. Several physical mechanisms are discussed.

  19. On the predictions of critical heat flux in rod bundles at low flow and low pressure conditions

    International Nuclear Information System (INIS)

    At low flow and low pressure conditions, critical heat flux (CHF) data for rod bundle geometry are very limited, and applicable design correlations are almost nonexistent. This paper investigates the applicability of recent CHF correlations developed for uniformly heated vertical annuli (for water mass flux ?250 kg/m2 s, and pressure of 0.118 MPa) to nonuniformly heated rod bundles. Results show that annuli correlations could be used to predict the CHF occurring at the same flow-regime transition in uniformly heated rod bundles. Also, the results demonstrate that the global conditions hypothesis (GCH), in conjunction with and annuli CHF correlations, may be used to predict CHF in nonuniformly heated rod bundles at low flow and low pressure conditions

  20. The Effects of Temperature, Pressure, and Humidity Variations on 100 Meter Sprint Performances

    CERN Document Server

    Mureika, J R

    2005-01-01

    It is well known that ``equivalent'' sprint race times run with different accompanying wind speeds or at different altitudes are anything but equivalent races. The drag force acting on a sprinter is a function of air density and the relative wind speed, where the former has traditionally been calculated using the race venue's elevation above sea level. However, air density variation is dependent on more than just altitude. This work will quantify how changes in air temperature, barometric pressure, and humidity levels influence 100 m sprint performances. When these effects are considered in combination, the corrections to performances can be very large. The results suggest that a non-negligible difference in race times can be expected for ``equivalent'' performances run with the same wind speed at the same venue or physical altitude, but under different atmospheric conditions.

  1. A study on the stem friction coefficient with differential pressure conditions for the motor operated flexible wedge gate valve

    International Nuclear Information System (INIS)

    Stem friction coefficient is very important parameter for the evaluation of valve performance. In this study, the characteristics of stem friction coefficient is analyzed, and the bounding value is determined. The hydraulic testing is performed for flexible wedge gate valves in the plant and statistical method is applied to the determination of bounding value. According to the results of this study, stem friction coefficient is not effected in low differential pressure condition, but it is showed different distribution in medium and high differential pressure condition. And the bounding value of closing stroke is higher than that of opening stroke

  2. Source and loading conditions in pressure suppression systems - results of the multivalent large scale pressure suppression experiments

    International Nuclear Information System (INIS)

    The paper deals mainly with the dynamic loading of the vent pipes and the wetwell walls as measured during the chugging regime and its sources. High speed pictures of the steam condensation correlated with pressure recordings help to clarify the pressure source mechanism during a chugging event. The resulting effective load on a vent pipe is measured with strain gages under the assumption that the pipe behaves like a cantilever beam. Frequency analyses of signals from accelerometers and strain gages at the wetwell walls reveal strong periodicities which are correlated with the chugging ringdown frequency of about 30 to 40 Hz. In impact analysis of the wetwell walls suggested the lowest, weak mode of the partly waterfilled wetwell to occur 40 Hz. This mode was not detected for the empty wetwell. Tentatively, the characteristic frequency of the chugging ringdown is attributed to a fluid-structure coupled vibration albeit the lowest acoustic mode of the pool is calculated to occur only at about 100 Hz with one-phase, room-temperature water. (orig./HP)

  3. Unusual atmospheric pressure chemical ionization conditions for detection of organic peroxides.

    Science.gov (United States)

    Rondeau, David; Vogel, René; Tabet, Jean-Claude

    2003-09-01

    Organic peroxides such as the cumene hydroperoxide I (M(r) = 152 u), the di-tert-butyl peroxide II (M(r) = 146 u) and the tert-butyl peroxybenzoate III (M(r) = 194 u) were analyzed by atmospheric pressure chemical ionization mass spectrometry using a water-methanol mixture as solvent with a low flow-rate of mobile phase and unusual conditions of the source temperature (probe temperature (70-200 degrees C). The mass spectra of these compounds show the formation of (i) an [M + H](+) ion (m/z 153) for the hydroperoxide I, (ii) a stable adduct [M + CH(3)OH(2)](+) ion (m/z 179) for the dialkyl peroxide II and (iii) several protonated adduct species such as protonated molecules (m/z 195) and different protonated adduct ions (m/z 227, 389 and 421) for the peroxyester III. Tandem mass spectrometric experiments, exact mass measurements and theoretical calculations were performed for characterize these gas-phase ionic species. Using the double-well energy potential model illustrating a gas-phase bimolecular reaction, three important factors are taken into account to propose a qualitative interpretation of peroxide behavior toward the CH(3)OH(2) (+), i.e. thermochemical parameters (DeltaHdegrees(reaction)) and two kinetic factors such as the capture constant of the initial stable ion-dipole and the magnitude of the rate constant of proton transfer reaction into the loose proton bond cluster. PMID:14505320

  4. Microstructure and spectroscopy studies on cubic boron nitride synthesized under high-pressure conditions

    CERN Document Server

    Nistor, L C; Dinca, G; Georgeoni, P; Landuyt, J V; Manfredotti, C; Vittone, E

    2002-01-01

    High-resolution electron microscopy (HREM) studies of the microstructure and specific defects in hexagonal boron nitride (h-BN) precursors and cubic boron nitride (c-BN) crystals made under high-pressure high-temperature conditions revealed the presence of half-nanotubes at the edges of the h-BN particles. Their sp sup 3 bonding tendency could strongly influence the nucleation rates of c-BN. The atomic resolution at extended dislocations was insufficient to allow us to determine the stacking fault energy in the c-BN crystals. Its mean value of 191 pm, 15 mJ m sup - sup 2 is of the same order of magnitude as that of diamond. High-frequency (94 GHz) electron paramagnetic resonance studies on c-BN single crystals have produced new data on the D1 centres associated with the boron species. Ion-beam-induced luminescence measurements have indicated that c-BN is a very interesting luminescent material, which is characterized by four luminescence bands and exhibits a better resistance to ionizing radiation than CVD di...

  5. Sulphate chemistry under pressurized oxidizing, reducing and fluctuating conditions; Sulfatkemi under trycksatta oxiderande, reducerande och fluktuerande foerhaallanden

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Yrjas, P.; Backman, P. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    In the literature it has been reported that sulfur capture with limestone (CaCO{sub 3}) under atmospheric fluidized bed combustion conditions reaches a maximum at about 850 deg C. Previously, the maximum has been attributed to the sintering of sorbent particles which decreases the reactive surface area. Lately, also another explanation has been reported. In this case the sulfur capture decrease at higher temperatures was concluded to be due to fluctuating oxidizing/reducing conditions in the atmospheric combustor. In this work the influence of alternating oxidizing/reducing conditions on SO{sub 2} capture at atmospheric and elevated pressure (15 bar) has been studied. In the pressurized case, the CO{sub 2} partial pressure was kept high enough to prevent CaCO{sub 3} from calcining and therefore the CaSO{sub 4} would not form CaO but CaCO{sub 3} under reducing conditions. The experiments were done with a pressurized TGA by periodically changing the gas environment between oxidizing (O{sub 2}. SO{sub 2}, CO{sub 2} and N{sub 2}) and slightly reducing (CO, SO{sub 2}, CO{sub 2} and N{sub 2}) gas mixtures at different temperatures. The results from the experiments showed that under normal pressure and slightly reducing conditions CaO formation from CaSO{sub 4} increased with temperature as expected. However, no significant amounts of CaCO{sub 3} were formed from CaSO{sub 4} at elevated pressure. It was also concluded that since the formation of CaO from CaSO{sub 4} was relatively slow it could not explain the sharp sulfur capture maximum at about 850 deg C. Therefore, it was assumed that the strongly reducing zones, where CaS thermodynamically is the stable compound, play a more important role concerning the sulfur capture in fluidized bed combustors. (orig.)

  6. Outflow boundary conditions for 3D simulations of non-periodic blood flow and pressure fields in deformable arteries

    CERN Document Server

    Vignon-Clementel, Irene; Jansen, K E; Taylor, C A; 10.1080/10255840903413565

    2010-01-01

    The simulation of blood flow and pressure in arteries requires outflow boundary conditions that incorporate models of downstream domains. We previously described a coupled multidomain method to couple analytical models of the downstream domains with 3D numerical models of the upstream vasculature. This prior work either included pure resistance boundary conditions or impedance boundary conditions based on assumed periodicity of the solution. However, flow and pressure in arteries are not necessarily periodic in time due to heart rate variability, respiration, complex transitional flow or acute physiological changes. We present herein an approach for prescribing lumped parameter outflow boundary conditions that accommodate transient phenomena. We have applied this method to compute haemodynamic quantities in different physiologically relevant cardiovascular models, including patient-specific examples, to study non-periodic flow phenomena often observed in normal subjects and in patients with acquired or congen...

  7. An Inexpensive Arterial Pressure Wave Sensor and its application in different physiological condition

    CERN Document Server

    Sur, S; Sur, Shantanu

    2005-01-01

    Arterial Blood Pressure wave monitoring is considered to be important in assessment of cardiovascular system. We developed a novel pulse wave detection system using low frequency specific piezoelectric material as pressure wave sensor. The transducer detects the periodic change in the arterial wall diameter produced by pressure wave and the amplified signal after integration represents the pressure wave. The signal before integration is proportional to the rate of change of pressure wave and it not only reproduces the pressure waveform faithfully, but also its sharper nature helps to reliably detect the heart period variability (HPV). We have studied the position-specific (e.g. over carotid or radial artery) nature of change of this pulse wave signal (shape and amplitude) and also the changes at different physiological states.

  8. Experimental determination of heat transfer critical conditions in water forced convection at low pressure in a circular channel

    International Nuclear Information System (INIS)

    An experimental determination was made of heat transfer critical conditions in a circular channel, uniformly heated, and internally cooled by water in ascending forced convection, under a pressure slightly above atmospheric pressure. Measurements were made of water flow, pressure, electric power temperature and heating, and a systematic analysis was made of the system's parameters. The values obtained for the heat critical flux are circa 50% lower than those predicted by Becker and Biasi and this is accounted to flowing instabilities of thermo-hydrodynamic nature. It is suggested that the flowing channels of circuits aiming at the study of the boiling crisis phenomenon be expanded in its upper extremity, and that the coolant circulation be kept through a pump with a pressure X flow characteristic as vertical as possible

  9. The lubrication characteristics of the vane tip under inlet pressure boundary conditions for an oil hydraulic vane pump

    International Nuclear Information System (INIS)

    The lubrication modes of line contact between the vane and the camring in an oil hydraulic vane pump have been investigated. First, variations of the radial acting force of a vane were calculated from previously measured results of the dynamic internal pressure in four chambers surrounding a vane. Next, distinctions of the lubrication modes were made using Hooke's chart, which represents an improvement over Johnson's chart. Finally, the influence of boundary conditions in the lubrication region on fluid film lubrication was examined by calculating film pressure distributions. The results show that the lubrication modes on the vane tip are a rigid-variable viscosity region. This region discharges pressure higher than 7 MPa, and exerts a great influence on oil film pressure in the large arc section due to the Peizo-viscous effect

  10. Analysis of flow induced valve operation and pressure wave propagation for single and two-phase flow conditions

    International Nuclear Information System (INIS)

    The flow induced valve operation is calculated for single and two-phase flow conditions by the fluid dynamic computer code DYVRO and results are compared to experimental data. The analysis show that the operational behaviour of the valves is not only dependent on the condition of the induced flow, but also the pipe flow can cause a feedback as a result of the induced pressure waves. For the calculation of pressure wave propagation in pipes of which the operation of flow induced valves has a considerable influence it is therefore necessary to have a coupled analysis of the pressure wave propagation and the operational behaviour of the valves. The analyses of the fast transient transfer from steam to two-phase flow show a good agreement with experimental data. Hence even these very high loads on pipes resulting from such fluid dynamic transients can be calculated realistically. (orig.)

  11. Optimization of hydrostatic pressure at varied sonication conditions - power density, intensity, very low frequency - for isothermal ultrasonic sludge treatment.

    Science.gov (United States)

    Delmas, Henri; Le, Ngoc Tuan; Barthe, Laurie; Julcour-Lebigue, Carine

    2015-07-01

    This work aims at investigating for the first time the key sonication (US) parameters: power density (DUS), intensity (IUS), and frequency (FS) - down to audible range, under varied hydrostatic pressure (Ph) and low temperature isothermal conditions (to avoid any thermal effect). The selected application was activated sludge disintegration, a major industrial US process. For a rational approach all comparisons were made at same specific energy input (ES, US energy per solid weight) which is also the relevant economic criterion. The decoupling of power density and intensity was obtained by either changing the sludge volume or most often by changing probe diameter, all other characteristics being unchanged. Comprehensive results were obtained by varying the hydrostatic pressure at given power density and intensity. In all cases marked maxima of sludge disintegration appeared at optimum pressures, which values increased at increasing power intensity and density. Such optimum was expected due to opposite effects of increasing hydrostatic pressure: higher cavitation threshold then smaller and fewer bubbles, but higher temperature and pressure at the end of collapse. In addition the first attempt to lower US frequency down to audible range was very successful: at any operation condition (DUS, IUS, Ph, sludge concentration and type) higher sludge disintegration was obtained at 12kHz than at 20kHz. The same values of optimum pressure were observed at 12 and 20kHz. At same energy consumption the best conditions - obtained at 12kHz, maximum power density 720W/L and 3.25bar - provided about 100% improvement with respect to usual conditions (1bar, 20kHz). Important energy savings and equipment size reduction may then be expected. PMID:25199444

  12. Flow Control Under Low-Pressure Turbine Conditions Using Pulsed Jets

    Science.gov (United States)

    Volino, Ralph J.; Ibrahim, Mounir B.

    2012-01-01

    This publication is the final report of research performed under an NRA/Cooperative Interagency Agreement, and includes a supplemental CD-ROM with detailed data. It is complemented by NASA/CR-2012-217416 and NASA/CR-2012-217417 which include a Ph.D. Dissertation and an M.S. thesis respectively, performed under this contract. In this study the effects of unsteady wakes and flow control using vortex generator jets (VGJs) were studied experimentally and computationally on the flow over the L1A low pressure turbine (LPT) airfoil. The experimental facility was a six passage linear cascade in a low speed wind tunnel at the U.S. Naval Academy. In parallel, computational work using the commercial code FLUENT (ANSYS, Inc.) was performed at Cleveland State University, using Unsteady Reynolds Averaged Navier Stokes (URANS) and Large Eddy Simulations (LES) methods. In the first phase of the work, the baseline flow was documented under steady inflow conditions without flow control. URANS calculations were done using a variety of turbulence models. In the second phase of the work, flow control was added using steady and pulsed vortex generator jets. The VGJs successfully suppressed separation and reduced aerodynamic losses. Pulsed operation was more effective and mass flow requirements are very low. Numerical simulations of the VGJs cases showed that URANS failed to capture the effect of the jets. LES results were generally better. In the third phase, effects of unsteady wakes were studied. Computations with URANS and LES captured the wake effect and generally predicted separation and reattachment to match the experiments. Quantitatively the results were mixed. In the final phase of the study, wakes and VGJs were combined and synchronized using various timing schemes. The timing of the jets with respect to the wakes had some effect, but in general once the disturbance frequency was high enough to control separation, the timing was not very important.

  13. Flow Control Under Low-Pressure Turbine Conditions Using Pulsed Jets: Experimental Data Archive

    Science.gov (United States)

    Volino, Ralph J.; Ibrahim, Mounir B.

    2012-01-01

    This publication is the final report of research performed under an NRA/Cooperative Interagency Agreement, and includes a supplemental CD-ROM with detailed data. It is complemented by NASA/CR-2012-217416 and NASA/CR-2012-217417 which include a Ph.D. Dissertation and an M.S. thesis respectively, performed under this contract. In this study the effects of unsteady wakes and flow control using vortex generator jets (VGJs) were studied experimentally and computationally on the flow over the L1A low pressure turbine (LPT) airfoil. The experimental facility was a six passage linear cascade in a low speed wind tunnel at the U.S. Naval Academy. In parallel, computational work using the commercial code FLUENT (ANSYS, Inc.) was performed at Cleveland State University, using Unsteady Reynolds Averaged Navier Stokes (URANS) and Large Eddy Simulations (LES) methods. In the first phase of the work, the baseline flow was documented under steady inflow conditions without flow control. URANS calculations were done using a variety of turbulence models. In the second phase of the work, flow control was added using steady and pulsed vortex generator jets. The VGJs successfully suppressed separation and reduced aerodynamic losses. Pulsed operation was more effective and mass flow requirements are very low. Numerical simulations of the VGJs cases showed that URANS failed to capture the effect of the jets. LES results were generally better. In the third phase, effects of unsteady wakes were studied. Computations with URANS and LES captured the wake effect and generally predicted separation and reattachment to match the experiments. Quantitatively the results were mixed. In the final phase of the study, wakes and VGJs were combined and synchronized using various timing schemes. The timing of the jets with respect to the wakes had some effect, but in general once the disturbance frequency was high enough to control separation, the timing was not very important. This is the supplemental CD-ROM

  14. Photochemical modelling of the Barcelona area under weak pressure synoptic summer conditions

    International Nuclear Information System (INIS)

    This city of Barcelona and its surrounding area, located in the western Mediterranean basin, can reach high levels of O3 in summertime under weak pressure synoptic conditions. To study the origin of this photochemical pollution, the episode that took place between the 3 and 5 August 1990 was chosen. The main meteorological mesoscale flows that take place in the region, such as sea and land breeze, convection cells and topographic injections, were reproduced with the meteorological non-hydrostatic mesoscale model MEMO for 5 August 1990. Industrial and commercial activity on 5 August 1990 was very low because it was a Sunday in the summer holiday period. Therefore, the emissions inventory calculated for this day in an area of 80x80 km2 around Barcelona showed that the main sources of VOC were traffic (51%) and vegetation (34%), while NOx were mostly emitted by traffic (88%). Photochemical simulation with the MARS model has shown that the combination of mesoscale circulations and local emissions is crucial in the production of O3. For instance, NOx inland transport towards regions where biogenic VOC are emitted causes the formation of O3, while topographic injections cause the formation of elevated O3 air layers. The synoptic wind, coming from the northeast in this case, also played an important role in advecting the air masses with local generated O3 away from their precursor emissio>3 away from their precursor emission sources. Evaluation of the model simulations is also performed and discussed by means of comparison of meteorological measurements in 9 surface stations and concentration measurements in 5 surface stations. (Author)

  15. Gas bubble dimensions in Archean lava flows indicate low air pressure at 2.7 Ga

    Science.gov (United States)

    Som, S. M.; Buick, R.; Hagadorn, J.; Blake, T.; Perreault, J.; Harnmeijer, J.; Catling, D. C.

    2014-12-01

    Air pressure constrains atmospheric composition, which, in turn, is linked to the Earth system through biogeochemical cycles and fluxes of volatiles from and to the Earth's interior. Previous studies have only placed maximum levels on surface air pressure for the early Earth [1]. Here, we calculate an absolute value for Archean barometric pressure using gas bubble size (vesicle) distributions in uninflated basaltic lava flows that solidified at sea level 2.7 billion years ago in the Pilbara Craton, Western Australia. These vesicles have been filled in by secondary minerals deposited during metasomatism and so are now amydules, but thin sections show that infilling did not change vesicle dimensions. Amygdule dimensions are measured using high-resolution X-ray tomography from core samples obtained from the top and bottom of the lava flows. The modal size expressed at the top and at the bottom of an uninflated flow can be linked to atmospheric pressure using the ideal gas law. Such a technique has been verified as a paleoaltimeter using Hawaiian Quaternary lava flows [2]. We use statistical methods to estimate the mean and standard deviation of the volumetric size of the amygdules by applying 'bootstrap'resampling and the Central Limit Theorem. Our data indicate a surprisingly low atmospheric pressure. Greater nitrogen burial under anaerobic conditions likely explains lower pressure. Refs: [1] Som et al. (2012) Nature 484, 359-262. D. L. Sahagian et al. (2002) J. Geol., 110, 671-685.

  16. Local charge transport properties of hydrazine reduced monolayer graphene oxide sheets prepared under pressure condition

    DEFF Research Database (Denmark)

    Ryuzaki, Sou; Meyer, Jakob Abild Stengaard

    2014-01-01

    Charge transport properties of chemically reduced graphene oxide (RGO) sheets prepared by treatment with hydrazine were examined using conductive atomic force microscopy. The current-voltage (I-V) characteristics of monolayer RGO sheets prepared under atmospheric pressure followed an exponentially increase due to 2D variable-range hopping conduction through small graphene domains in an RGO sheet containing defect regions of residual sp3carbon clusters bonded to oxygen groups, whereas RGO sheets prepared in a closed container under moderate pressure showed linear I-V characteristics with a conductivity of 267.2-537.5S/m. It was found that the chemical reduction under pressure results in larger graphene domains (sp2networks) in the RGO sheets when compared to that prepared under atmospheric pressure, indicating that the present reduction of GO sheets under the pressure is one of the effective methods to make well-reduced GO sheets.

  17. Local charge transport properties of hydrazine reduced monolayer graphene oxide sheets prepared under pressure condition

    Science.gov (United States)

    Ryuzaki, Sou; Meyer, Jakob A. S.; Petersen, Søren; Nørgaard, Kasper; Hassenkam, Tue; Laursen, Bo W.

    2014-09-01

    Charge transport properties of chemically reduced graphene oxide (RGO) sheets prepared by treatment with hydrazine were examined using conductive atomic force microscopy. The current-voltage (I-V) characteristics of monolayer RGO sheets prepared under atmospheric pressure followed an exponentially increase due to 2D variable-range hopping conduction through small graphene domains in an RGO sheet containing defect regions of residual sp3 carbon clusters bonded to oxygen groups, whereas RGO sheets prepared in a closed container under moderate pressure showed linear I-V characteristics with a conductivity of 267.2-537.5 S/m. It was found that the chemical reduction under pressure results in larger graphene domains (sp2 networks) in the RGO sheets when compared to that prepared under atmospheric pressure, indicating that the present reduction of GO sheets under the pressure is one of the effective methods to make well-reduced GO sheets.

  18. Local charge transport properties of hydrazine reduced monolayer graphene oxide sheets prepared under pressure condition

    Energy Technology Data Exchange (ETDEWEB)

    Ryuzaki, Sou, E-mail: ryuzaki.soh.341@m.kyushu-u.ac.jp; Meyer, Jakob A. S.; Petersen, Søren; Nørgaard, Kasper; Hassenkam, Tue; Laursen, Bo W. [Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetparken 5, 2100 Københaven Ø (Denmark)

    2014-09-01

    Charge transport properties of chemically reduced graphene oxide (RGO) sheets prepared by treatment with hydrazine were examined using conductive atomic force microscopy. The current-voltage (I-V) characteristics of monolayer RGO sheets prepared under atmospheric pressure followed an exponentially increase due to 2D variable-range hopping conduction through small graphene domains in an RGO sheet containing defect regions of residual sp{sup 3} carbon clusters bonded to oxygen groups, whereas RGO sheets prepared in a closed container under moderate pressure showed linear I-V characteristics with a conductivity of 267.2?537.5?S/m. It was found that the chemical reduction under pressure results in larger graphene domains (sp{sup 2} networks) in the RGO sheets when compared to that prepared under atmospheric pressure, indicating that the present reduction of GO sheets under the pressure is one of the effective methods to make well-reduced GO sheets.

  19. Surgical Space Conditions During Low-Pressure Laparoscopic Cholecystectomy with Deep Versus Moderate Neuromuscular Blockade : A Randomized Clinical Study

    DEFF Research Database (Denmark)

    Staehr-Rye, Anne K; Rasmussen, Lars S.

    2014-01-01

    BACKGROUND: Laparoscopic cholecystectomy performed during low intraabdominal pressure (<12 mm Hg) is associated with significantly less postoperative pain than standard pressure (?12 mm Hg). The impact on surgical space conditions and safety of operating at lower pressures has not been adequately described, but deep neuromuscular blockade may be beneficial. We investigated if deep muscle relaxation would be associated with a higher proportion of procedures with "optimal" surgical space conditions compared with moderate relaxation during low-pressure (8 mm Hg) laparoscopic cholecystectomy. METHODS: In this assessor-blinded study, 48 patients undergoing elective laparoscopic cholecystectomy were administered rocuronium for neuromuscular blockade and randomized to either deep neuromuscular blockade (rocuronium bolus plus infusion maintaining a posttetanic count 0-1) or moderate neuromuscular blockade (rocuronium repeat bolus only for inadequate surgical conditions with spontaneous recovery of neuromuscular function). Patients received anesthesia with propofol, remifentanil, and rocuronium. The primary outcome was the proportion of procedures with optimal surgical space conditions (assessed by the surgeon as 1 on a 4-point scale). Secondary outcomes included the proportion of procedures completed at pneumoperitoneum 8 mm Hg and surgical space conditions on dissection of the gallbladder (numeric rating scale 0-100; 0 = optimal surgical space conditions; 100 = unacceptable surgical space conditions). RESULTS: Optimal surgical space conditions during the entire procedure were observed in 7 of 25 patients allocated to deep neuromuscular blockade and in 1 of 23 patients allocated to moderate blockade (P = 0.05) with an absolute difference of 24% between the groups (95% confidence interval, 4%-43%). Laparoscopic cholecystectomy was completed at pneumoperitoneum 8 mm Hg in 15 of 25 and 8 of 23 patients in the deep and moderate group, respectively (95% confidence interval, -2% to 53%; P = 0.08). Surgical space conditions during dissection of the gallbladder assessed by use of the numeric rating scale were 20 (10-50) (median [25%-75% range]) in the deep neuromuscular blockade group and 30 (10-50) in the moderate group (P = 0.58; Wilcoxon-Mann-Whitney odds, 1.2; 95% confidence interval, 0.6-2.5). No operations were converted to laparotomy. CONCLUSIONS: Deep neuromuscular blockade was associated with surgical space conditions that were marginally better than with moderate muscle relaxation during low-pressure laparoscopic cholecystectomy.

  20. Valve inlet fluid conditions for pressurizer safety and relief valves in Westinghouse-designed plants. Final report

    International Nuclear Information System (INIS)

    The overpressure transients for Westinghouse-designed NSSSs are reviewed to determine the fluid conditions at the inlet to the PORV and safety valves. The transients considered are: licensing (FSAR) transients; extended operation of high pressure safety injection system; and cold overpressurization. The results of this review, presented in the form of tables and graphs, define the range of fluid conditions expected at the inlet to pressurized safety and power-operated relief valves utilized in Westinghouse-designed PWR units. These results will provide input to the PWR utilities in their justification that the fluid conditions under which their valve designs were tested as part of the EPRI/PWR Safety and Relief Valve Test Program indeed envelop those expected in their units

  1. Seasonal variation in the incidence of preeclampsia and eclampsia in tropical climatic conditions

    Directory of Open Access Journals (Sweden)

    Subramaniam Vidya

    2007-10-01

    Full Text Available Abstract Background Observational studies have demonstrated various correlations between hypertensive disorders of pregnancy and different weather parameters. We aim to study if a correlation exists between the incidence of eclampsia and pre-eclampsia and various weather parameters in the tropical coastal city of Mumbai which has the distinction of having relatively uniform meteorological variables all throughout the year, except for the monsoon season. Methods We retrospectively analysed data from a large maternity centre in Mumbai, India over a period of 36 months from March 1993 to February 1996, recording the incidence of preeclampsia and eclampsia. Meteorological data was acquired from the regional meteorological centre recording the monthly average temperature, humidity, barometric pressure and rainfall during the study period. Study period was then divided into two climate conditions: monsoon season (June to August and dry season September to May. The incidence of preeclampsia and eclampsia and the meteorological differences between the two seasons were compared. Results Over a 36-month period, a total of 29562 deliveries were recorded, of which 1238 patients developed preeclampsia (4.18% and 34 developed eclampsia (0.11%. The incidence of preeclampsia did not differ between the monsoon and the dry season (4.3% vs. 4.15%, p = 0.5. The incidence of eclampsia was significantly higher in the monsoon (0.2% vs. 0.08%, p = 0.01. The monsoon was significantly cooler (median maximum temperature 30.7°C vs. 32.3°C, p = 0.01, more humid (median relative humidity 85% vs. 70%, p = 0.0008, and received higher rainfall (median 504.9 mm vs. 0.3 mm, p = 0.0002 than the rest of the year. The median barometric pressure (1005 mb during the monsoon season was significantly lower than the rest of the year (1012 mb, p Conclusion In the tropical climate of Mumbai, the incidence of eclampsia is significantly higher in monsoon, when the weather is cooler and humid with a lower barometric pressure than the rest of the year. This effect is not seen with preeclampsia. This strengthens the association of low temperature and high humidity with triggering of eclampsia.

  2. Development and calibration of differential mobility analyzer for 20 to 80 nm particles under low pressure conditions.

    Science.gov (United States)

    Mun, Ji Hun; Cho, Dae Guen; Kim, Young Jin; Choi, Jae Boong; Kang, Sang Woo; Yun, Ju Young; Shin, Yong Hyeon; Kim, Tae Sung

    2011-07-01

    The vienna-type differential mobility analyzer (DMA) was developed for the measurement of wide-range nm-sized particles under low-pressure conditions (2.9-8 kPa) with the faraday cup electrometer (FCE). The length, inner and outer diameter of DMA are calculated as a function of flow rate, applied voltage, pressure, and particle diameter to avoide breakdown in DMA. The algorithm for the diffusion transfer function of the DMA was successfully developed and verified by comparing the numerical and experimental results. The DMA was calibrated via the tandem DMA (TDMA) method which using two DMA in parallel. The inversion algorithm was applied to the size distribution obtained from the current of the FCE. The calibration experiment was performed with 1% NaCl particles under atmospheric and low-pressure conditions. The calibration result showed that the development of the DMA was successful as it was able to measure 20- to 80-nm paricles under low-pressure conditions with various flow rates (0.1-0.5 l/min). PMID:22121701

  3. Real-Time Optical Monitoring of Flow Kinetics and Gas Phase Reactions Under High-Pressure OMCVD Conditions

    Science.gov (United States)

    Dietz, N.; McCall, S.; Bachmann, K. J.

    2001-01-01

    This contribution addresses the real-time optical characterization of gas flow and gas phase reactions as they play a crucial role for chemical vapor phase depositions utilizing elevated and high pressure chemical vapor deposition (HPCVD) conditions. The objectives of these experiments are to validate on the basis of results on real-time optical diagnostics process models simulation codes, and provide input parameter sets needed for analysis and control of chemical vapor deposition at elevated pressures. Access to microgravity is required to retain high pressure conditions of laminar flow, which is essential for successful acquisition and interpretation of the optical data. In this contribution, we describe the design and construction of the HPCVD system, which include access ports for various optical methods of real-time process monitoring and to analyze the initial stages of heteroepitaxy and steady-state growth in the different pressure ranges. To analyze the onset of turbulence, provisions are made for implementation of experimental methods for in-situ characterization of the nature of flow. This knowledge will be the basis for the design definition of experiments under microgravity, where gas flow conditions, gas phase and surface chemistry, might be analyzed by remote controlled real-time diagnostics tools, developed in this research project.

  4. EXAFS measurements under high pressure conditions using a combination of a diamond anvil cell and synchrotron radiation

    International Nuclear Information System (INIS)

    EXAFS spectra for Fe, Co, Ni K-edges were successfully measured under high pressure conditions using a combination of a set of normal 1/8 carat diamond anvils, synchrotron radiation and a scintillation counter. A newly developed motor controlled goniometer stage was used for adjusting the position of a miniature diamond anvil cell. On the measurement of Cr and Mn spectra, specially designed thinner diamond anvil was necessary. EXAFS analysis of bis(dimethylglyoximato)nickel(II) at pressures from 1 atm to 5.6 GPa was made. (author)

  5. Dispersion and aggregation of nanoparticles derived from colloidal droplets under low-pressure conditions.

    Science.gov (United States)

    Wang, Wei-Ning; Lenggoro, I Wuled; Okuyama, Kikuo

    2005-08-15

    Formation of individually dispersed nanoparticles or compactly aggregated nanoparticles from sols via a spray-drying route at low pressure was investigated experimentally. Silica sol was used as a sample material. Effects of operating temperature, colloid size, sol concentration, pressure, pH and zeta potential of sols on the morphology of product particles were investigated. From the experimental results, it was shown that dispersed nanoparticles could be obtained at a relatively low pressure (20 Torr) and low temperature (200 degrees C). The experiment also showed that dispersed nanoparticles could be achieved by careful control of the interfacial energy (pH value) of the colloidal precursor. A possible mechanism of sol-to-dry-particle formation in the spray-drying process at low pressure is suggested, based on the experimental results and the available theories. This mechanism was able to explain the experimental results well. PMID:15927609

  6. In-line pressure within a HOTLINE(®) Fluid Warmer, under various flow conditions.

    Science.gov (United States)

    Higashi, Midoriko; Yamaura, Ken; Matsubara, Yukie; Fukudome, Takuya; Hoka, Sumio

    2015-04-01

    Roller pump infusion devices are widely used for rapid infusion, and may be combined with separate warming devices. There may be instances however, where the pressures generated by the roller pump may not be compatible with the warming device. We assessed a commonly used roller pump in combination with a HOTLINE(®) Fluid Warmer, and found that it could generate pressures exceeding the HOTLINE(®) manufacturers specifications. This was of concern because the HOTLINE(®) manufacturer guideline states that not for use with pressure devices generating over 300 mmHg. Pressure greater than 300 mmHg may compromise the integrity of the HOTLINE(®) Fluid Warming Set. The aim of this study was to compare in-line pressure within a HOTLINE(®) Fluid Warmer at different infusion rates of a roller pump using various sizes of intravenous cannulae. The rapid infusion system comprised a 500 mL-normal saline bag, roller pump type infusion device, HOTLINE(®) Fluid Warmer (blood and fluid warmer system), and six different sizes of intravenous cannulae. In-line pressure was measured proximal to the HOTLINE(®) (pre-warmer) and proximal to the cannula (post-warmer), at flow rate of 50-160 mL/min. The in-line pressures increased significantly with increasing flow rate. The pre-warmer pressures exceeded 300 mmHg when the flow rate was ?120 mL/min with 20-gauge, 48 mm length cannula, 130 with 20-gauge, 25 mm cannula, and 160 mL/min with 18-gauge, 48 mm cannula. However, they were <300 mmHg at any flow rates with 18-gauge, 30 mm cannula and 16-gauge cannulae. The post-warmer pressures exceeded 300 mmHg at the flow rate of 140 mL/min with 20-gauge, 48 mm cannula, and 160 mL/min with 20-gauge, 25 mm cannula, while they were <300 mmHg at any flow rates with 18 and 16-gauge cannulae. The in-line pressure within a HOTLINE(®) could exceed 300 mmHg, depending on the flow rate and size and length of cannula. It is important to pay attention to the size and length of cannulae and flow rate to keep the maximum in-line pressure <300 mmHg when a roller pump type infusion device is used. PMID:25087123

  7. Osmosis-induced water uptake by Eurobitum bituminized radioactive waste and pressure development in constant volume conditions

    Energy Technology Data Exchange (ETDEWEB)

    Marieen, A., E-mail: amarien@sckcen.be [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Mokni, N., E-mail: Nadia.mokni@upc.edu [Department of Geotechnical Engineering and Geosciences, Universidad Politecnica de Catalunya (UPC), Calle Gran Capitan, s/n, Edificio C-1, 08034 Barcelona (Spain); Valcke, E. [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Olivella, S. [Department of Geotechnical Engineering and Geosciences, Universidad Politecnica de Catalunya (UPC), Calle Gran Capitan, s/n, Edificio C-1, 08034 Barcelona (Spain); Smets, S. [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Li, X., E-mail: xli@sckcen.be [EIG EURIDICE, Boeretang 200, 2400 Mol (Belgium)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer The water uptake by Eurobitum is studied to judge the safety of geological disposal. Black-Right-Pointing-Pointer High pressures of up to 20 MPa are measured in constant volume water uptake tests. Black-Right-Pointing-Pointer The morphology of leached Eurobitum samples is studied with {mu}CT and ESEM. Black-Right-Pointing-Pointer The observations are reproduced by an existing CHM formulation for Eurobitum. - Abstract: The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at Belgian Nuclear Research Center SCK-CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluna, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO{sub 3} leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography ({mu}CT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to values that can be (in theory) as high as 42.8 MPa, being the osmotic pressure of a saturated NaNO{sub 3} solution. After about four years of hydration in nearly constant volume water uptake tests, pressures up to 20 MPa are measured. During this hydration period only the outer layers with a thickness of 1-2 mm were hydrated (as derived from {mu}CT and ESEM analyses), and only about 10-20% of the initial NaNO{sub 3} content was released by the samples. In the studied test conditions, the rates of water uptake and NaNO{sub 3} leaching are low because of the low porosity, and thus low permeability, of the hydrated BW samples in combination with a highly efficient semi-permeable bitumen membrane. In contrast to the hydration in free swelling conditions, the increase in porosity is limited by the high pressures in the nearly constant volume tests. Furthermore, at the interface with the stainless steel filters, a low permeable re-compressed bitumen layer is formed, as observed on the ESEM images. The experimental results of pressure increase and NaNO{sub 3} leaching, as well as observations on {mu}CT and ESEM images (e.g. compression of leached layers, high dissolved NaNO{sub 3} concentration in hydrated BW after about four years), were reproduced rather successfully by the coupled CHM formulation for Eurobitum BW. A long-term model prediction of the evolution of the osmosis-induced pressure in the nearly constant volume tests shows that the pressure would reach a maximal value of about 20 MPa after about 5.5 years, after which the pressure would start to decrease. After 10,000 days ({approx}27 years) the pressure would have decreased to a value of {approx}2 MPa.

  8. Contact area and pressure distribution in the feline patellofemoral joint under physiologically meaningful loading conditions.

    Science.gov (United States)

    Clark, A L; Herzog, W; Leonard, T R

    2002-01-01

    The purpose of this study was to determine contact area and mean and peak pressures in the healthy feline patellofemoral joint over the complete range of possible applied force. Furthermore, we wanted to improve upon the repeatability of previous measurements while maximizing the physiological relevance of the results obtained. The patellae and femora were secured in a loading frame approximating an in situ loading configuration. Low- and medium-grade Fuji film was used to assess patellofemoral contact area and pressure distribution, respectively. Constant force was applied to the patellofemoral joints for 2s (short duration trials) or 5min (long duration trials). For the short duration trials, contact area was shown to increase logarithmically with the force applied. In contrast, mean and peak pressures increased linearly with force. Furthermore, the rate of increase of peak pressure with force was approximately three times greater than that of mean pressure. For the long duration trials, contact area increased up to 33% compared to the short duration trials. This effect could no longer be detected with our approach after an unloading period of 5-10s. Increasing contact area is one mechanism that the feline patellofemoral joint may use to regulate the pressures experienced by the cartilage as the force applied to the joint increases. The attenuation of external forces inside a joint is achieved by the specific geometry of the articulating surfaces and the viscoelastic properties of the articular cartilage. It likely represents a natural protection of joints to high external load magnitudes. PMID:11747883

  9. A pressure correction scheme for generalized form of energy-stable open boundary conditions for incompressible flows

    CERN Document Server

    Dong, Suchuan

    2014-01-01

    We present a generalized form of open boundary conditions, and an associated numerical algorithm, for simulating incompressible flows involving open or outflow boundaries. The generalized form represents a family of open boundary conditions, which all ensure the energy stability of the system, even in situations where strong vortices or backflows occur at the open/outflow boundaries. Our numerical algorithm for treating these open boundary conditions is based on a rotational pressure correction-type strategy, with a formulation suitable for $C^0$ spectral-element spatial discretizations. We have introduced a discrete equation and associated boundary conditions for an auxiliary variable. The algorithm contains constructions that prevent a numerical locking at the open/outflow boundary. In addition, we have also developed a scheme with a provable unconditional stability for a sub-class of the open boundary conditions. Extensive numerical experiments have been presented to demonstrate the performance of our meth...

  10. Evaluation of environmentally-assisted cracking in the simulated PWR primary water conditions for pressure vessel and piping materials

    International Nuclear Information System (INIS)

    Two pressure vessel steels (A533 Gr.B, cl.1 and A508 cl.3) and high strength cast and forged stainless steels (CF8A and 316LN) which have been expected as the promising piping materials for PWR primary piping systems were evaluated concerning the reliability in the simulated PWR primary water conditions. Metallurgical and mechanical properties of these new materials lied completely within the specifications. Corrosion fatigue tests for the reactor pressure vessel steels and stress corrosion cracking tests for stainless steels were performed in simulated PWR high temperature water environment. The results are sammarized as follows: (1) Reactor Pressure Vessel Steels (A533B cl.1 and A508 cl.3). Both under air and high temperature water conditions, no significant difference of the fatigue crack growth rate was found in these steels. In comparison with the ASME reference curves in air, a little acceleration effect on crack growth rate in the water condition was observed in a certain stress intensity factor range (low ?K). This environmentally assisted crack growth rate could be negligible. (2) SCC Resistance of cast and forged Stainless Steels (CF8A and 316LN). Following three kinds of SCC tests, constant extention rate test, cyclic tensile test and constant load test were conducted. Even in the heavily sensitized stainless steels, no SCC was observed. These results indicate that CF8A and 316LN stainless steels have enough resistance against SCC in the PWR primary water nce against SCC in the PWR primary water condition. (author)

  11. Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing

    International Nuclear Information System (INIS)

    Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m-3 in summer to about 800-1400 Bq m-3 in winter, indicating winter ventilation rates varying from 0.6 to 2.5 x 10-6 s-1. Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from -7 to -26 Bq m-3 hPa-1. This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. Iton-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes.

  12. Re-investigation of the crystal structure of enstatite under high-pressure conditions

    DEFF Research Database (Denmark)

    Periotto, Benedetta; Balic Zunic, Tonci

    2012-01-01

    A synthetic single crystal of pure orthoenstatite (MgSiO3, space group Pbca) has been investigated at high pressure for structural determinations by in situ single-crystal X?ray diffraction using a diamond-anvil cell. Ten complete intensity data collections were performed up to 9.36 GPa. This study significantly improved the accuracy of structural parameters in comparison to a previous high-pressure structural study, allowing a more detailed examination of structural behavior of orthoenstatite at high pressures and a comparison to other more recent structural studies performed on orthopyroxenes with different compositions. The structural evolution determined in this work confirms the high-pressure evolution found previously for other orthopyroxenes and removes some ambiguities originating from the less accurate published data on the MgSiO3 structure at high pressure. The structural compression is mostly governed by significant volume decrease of the Mg1 and Mg2 octahedra, affecting in turn the kink of the tetrahedral chains, especially the TB chain of larger SiO4 tetrahedra. The Mg2 polyhedron undergoes the largest volume variation, 8.7%, due especially to the strong contraction of the longest bond distance (Mg2-O3B), whereas Mg1 polyhedral volume decreases by about 7.4%. The compressional behavior of the tetrahedral sites is quite different from previously published data. The TA and TB tetrahedral volumes decrease by about 2.8 and 1.8%, respectively, and no discontinuities can be observed in the pressure range investigated. Using the data on the pure orthoenstatite as reference, we can confirm the basic influences of element substitutions on the evolution of the crystal structure with pressure.

  13. Synthesis of novel Ru2C under high pressure-high temperature conditions

    International Nuclear Information System (INIS)

    We report here, for the first time, synthesis of the Fe2N type hexagonal phase of ruthenium carbide by a high pressure-high temperature technique using a laser heated diamond anvil cell (LHDAC). The synthesis is carried out by laser heating a mixture of pure elements, Ru and C, at very low ‘pressure’ of 5 GPa and T ? 2000 K. The structure of the temperature quenched high pressure phase is characterized by in situ high pressure x-ray diffraction (HPXRD) and is corroborated by ex situ TEM imaging and diffraction, carried out for the first time on the retrieved sample synthesized by LHDAC. The lattice parameters of Ru2C at ambient pressure are found to be a = 2.534 ? and c = 4.147 ?. In situ HPXRD studies up to 14.2 GPa yield a bulk modulus of 178(4) GPa. Electronic structure calculations reveal the system to be metallic in nature with a degree of covalence along the Ru-C bond. As ruthenium is isoelectronic to osmium, this result for Ru2C has significant implications in the synthesis and study of osmium carbides.

  14. Multiphase Binary Mixture Flows in Porous Media in a Wide Pressure and Temperature Range Including Critical Conditions

    Science.gov (United States)

    Afanasyev, A.

    2011-12-01

    Multiphase flows in porous media with a transition between sub- and supercritical thermodynamic conditions occur in many natural and technological processes (e.g. in deep regions of geothermal reservoirs where temperature reaches critical point of water or in gas-condensate fields where subject to critical conditions retrograde condensation occurs and even in underground carbon dioxide sequestration processes at high formation pressure). Simulation of these processes is complicated due to degeneration of conservation laws under critical conditions and requires non-classical mathematical models and methods. A new mathematical model is proposed for efficient simulation of binary mixture flows in a wide range of pressures and temperatures that includes critical conditions. The distinctive feature of the model lies in the methodology for mixture properties determination. Transport equations and Darcy law are solved together with calculation of the entropy maximum that is reached in thermodynamic equilibrium and determines mixture composition. To define and solve the problem only one function - mixture thermodynamic potential - is required. Such approach allows determination not only single-phase states and two-phase states of liquid-gas type as in classical models but also two-phase states of liquid-liquid type and three-phase states. The proposed mixture model was implemented in MUFITS (Multiphase Filtration Transport Simulator) code for hydrodynamic simulations. As opposed to classical approaches pressure, enthalpy and composition variables together with fully implicit method and cascade procedure are used. The code is capable of unstructured grids, heterogeneous porous media, relative permeability and capillary pressure dependence on temperature and pressure, multiphase diffusion, optional number of sink and sources, etc. There is an additional module for mixture properties specification. The starting point for the simulation is a cubic equation of state that is used for mixture thermodynamic potential - entropy - calculation in pressure, enthalpy and composition variables. A polynomial spline is implemented to save the potential for subsequent hydrodynamic simulations. At this stage the majority of complicated thermodynamic procedures are performed prior to hydrodynamic that results in sufficient acceleration of calculations. The code was used for analysis of multiphase water-carbon dioxide mixture flows in porous media. Using the developed methodology the mixture phase diagram was calculated both below and above critical point of water. A zone of three-phase state conditions was detected where the mixture splits in three phases: liquid water and liquefied and gaseous carbon dioxide. The mixture flows subjected to formation of the three-phase flow region were investigated. The work is supported by Grant of the President of the Russian Federation (575.2010.1, 4810.2010.1).

  15. A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines under a Wide Range of Operating Conditions

    Science.gov (United States)

    Suzen, Y. B.; Huang, P. G.; Ashpis, D. E.; Volino, R. J.; Corke, T. C.; Thomas, F. O.; Huang, J.; Lake, J. P.; King, P. I.

    2007-01-01

    A transport equation for the intermittency factor is employed to predict the transitional flows in low-pressure turbines. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, mu(sub p) with the intermittency factor, gamma. Turbulent quantities are predicted using Menter's two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model which can produce both the experimentally observed streamwise variation of intermittency and a realistic profile in the cross stream direction. The model had been previously validated against low-pressure turbine experiments with success. In this paper, the model is applied to predictions of three sets of recent low-pressure turbine experiments on the Pack B blade to further validate its predicting capabilities under various flow conditions. Comparisons of computational results with experimental data are provided. Overall, good agreement between the experimental data and computational results is obtained. The new model has been shown to have the capability of accurately predicting transitional flows under a wide range of low-pressure turbine conditions.

  16. Equation of state density models for hydrocarbons in ultradeep reservoirs at extreme temperature and pressure conditions

    Science.gov (United States)

    Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.

    2013-10-01

    The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.

  17. Plain-jet airblast atomization of alternative liquid petroleum fuels under high ambient air pressure conditions

    Science.gov (United States)

    Jasuja, A. K.

    1982-04-01

    The effects that air and fuel properties have upon the spray mean drop size characteristics of a plain-jet airblast atomizer of the type employed in the gas turbine engine are investigated. The tests used kerosene, gas oil and a high-viscosity blend of gas oil in residual fuel oil, and covered a wide range of ambient air pressures. Laser light-scattering technique was employed for drop size measurements. It is concluded that the atomizer's measured mean drop size characteristics are only slightly different from those of the pre-filming type, especially when operating on low-viscosity kerosene under higher ambient air pressure. The beneficial effect of increased levels of ambient air pressure on mean drop size is shown to be much reduced in the case of high-viscosity fuels, thus making the attainment of good atomization performance on such fuels difficult. An expression is derived for correlating the obtained mean drop size data.

  18. Influence of deformation conditions on texture formation and ductility in titanium alloys under hydrostatic pressure

    International Nuclear Information System (INIS)

    The influence of hot pressing parameters on microstructure, texture and mechanical properties of bars from titanium alloys VT1-0, VT5-1, (?-alloys) and VT3-1 (?+?-alloy) has been investigated. Mechanical testing of samples has been performed under hydrostatic pressure from 200 to 800 MPa. It is shown that the temperature, deformation degree and type of the structure obtained exert a slight effect on mechanical properties of bars. The texture heterogeneity is more pronounced in ?-alloys. It has been found that hydrostatic pressure during sample tensile testing improves their ductility characteristics

  19. Condensation phenomena in BWR-pressure suppression containments under LOCA conditions

    International Nuclear Information System (INIS)

    Experimental studies on condensation phenomena in pressure suppression systems (PSS) have shown, that chugging produces the major dynamic loads in a PSS. Time correlation of digital and visual data have produced understanding of the essential physics of this phenomenon: chugging events are characterized by pipe outside and pipe inside condensation. Pipe outside condensation is smooth, sometimes accompanied by vent pipe acoustic frequency. Pipe inside condensation is ring-like and induces a strong pressure pulse with ringdown frequency. The steam ring is caused by the retreating steam front in the pipe exit, which acts as a BORDA-mouth. (orig.)

  20. Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions

    OpenAIRE

    Groot, S.P.C.; Surki, A. A.; de Vos, R. C. H.; Kodde, J.

    2012-01-01

    Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds w...

  1. Space-dependent core/reflector boundary conditions generated by the boundary element method for pressurized water reactors

    International Nuclear Information System (INIS)

    This paper reports on the boundary element method used to generate energy-dependent matrix-type boundary conditions along core/reflector interfaces and along baffle-plate surfaces of pressurized water reactors. This method enables one to deal with all types of boundary geometries including convex and concave corners. The method is applicable to neutron diffusion problems with more than two energy groups and also can be used to model a reflector with or without a baffle plate. Excellent eigenvalue and flux shape results can be obtained when the boundary conditions generated by this technique are coupled with core-only finite difference calculations

  2. Crack growth behaviour of low-alloy steels for pressure boundary components under transient light water reactor operating conditions - CASTOC, Part I: BWR/NWC conditions

    International Nuclear Information System (INIS)

    One of the ageing phenomena of pressure boundary components of light water reactors (LWR) is environmentally-assisted cracking (EAC). The project CASTOC (5. Framework Programme of the EU) was launched September 2000 with six European partners and terminated August 2003. It was focused in particular on the EAC behaviour of low-alloy steels (LAS) and to some extent to weld metal, heat affected zone and the influence of an austenitic cladding. The main objective was directed to the clarification of EAC crack growth behaviour/mechanism of LAS in high-temperature water under steady-state power operation (constant load) and transient operating conditions (e.g., start-up/shut-down, transients in water chemistry and load). Autoclave tests were performed with Western and Russian type reactor pressure vessel steels under simulated boiling water reactor (BWR)/normal water chemistry (NWC) and pressurised water reactor (VVER) conditions. The investigations were performed with fracture mechanics specimens of different sizes and geometries. The applied loading comprised cyclic loads, static loads and load spectra where the static load was periodically interrupted by partial unloading. With regard to water chemistry, the oxygen content (VVER) and impurities of sulphate and chlorides (BWR) were varied beyond allowable limits for continuous operation. The current paper summarises the most important crack growth results obtained under simulated BWR/NWC conditions. The results are discussed in the context of the current crack growth rate curves in the corresponding nuclear codes. (authors)

  3. Theoretical study of possible benzene dimerizations under high-pressure conditions

    International Nuclear Information System (INIS)

    We offer a theoretical explanation of the rate processes observed macroscopically in materials composed of aromatic ring structures subjected to high pressure. Earlier workers have made qualitative suggestions that the origin of these processes may be due to interring pi bonding. By making quantum-mechanical calculations on a simple special case of such systems (i.e., two interacting benzene rings), we attempt to produce a quantitative microscopic foundation for the suggestions. We briefly review earlier experimental and theoretical work on the subject and thereby motivate the working hypotheses used in the calculations. The principal hypothesis is that by studying restricted parts of the two benzene-ring energy hypersurface, we can learn something about the pressure-induced rate process for all the arene structures. By use of the modified-neglect-of-diatomic-differential-overlap (MNDO) method and the generalized valence bond ''perfect-pairing'' (GVP--PP) method supplemented by configuration interaction, we found two metastable ground electronic state dimers of benzene; we suggest that one of these is the source of the observed rate process seen in benzene at high pressure. Further, we suggest that analogous dimerizations are responsible for the rate processes seen in larger arene materials subjected to very high pressures. The detailed geometries and energies of both benzene dimers are given. Suggestions for experimentally testing whether the proposed explanation is sting whether the proposed explanation is correct are given

  4. Aluminum oxide films deposited in low pressure conditions by reactive pulsed dc magnetron sputtering

    CERN Document Server

    Seino, T

    2002-01-01

    The reactive pulsed dc sputtering technique is widely used for the deposition of oxide films. The operating pressure for sputtering is commonly above 0.13 Pa. In this study, however, aluminum oxide (alumina) films were deposited at operating pressures from 0.06 to 0.4 Pa using a sputtering system equipped with a scanning magnetron cathode and a pulsed dc power supply. The pulsed dc power was found to be useful not only to reduce arcing, but also to sustain the discharge at low pressure. The electrical breakdown field, intrinsic stress, O/Al ratio, refractive index, and surface roughness were investigated. Both a low intrinsic stress and an O/Al ratio around the stoichiometry were required to get the film having a high breakdown field. A low operating pressure of 0.1 Pa was found to provide the necessary stress and O/Al ratio targets. A 50-nm-thick alumina film having a maximum breakdown field of 7.4 MV/cm was obtained.

  5. Crack growth behaviour of low-alloy steels for pressure boundary components under transient light water reactor operating conditions - CASTOC, Part II: WWER conditions

    International Nuclear Information System (INIS)

    One of the ageing phenomena of pressure boundary components of light water reactors (LWRs) is environmentally-assisted cracking (EAC). The project CASTOC (5. Framework Programme of the EU) was launched September 2000 with six European partners and terminated August 2003. It focused in particular on the EAC behaviour of low-alloy steels (LAS) and to some extent to weld metal, heat affected zone and the influence of an austenitic cladding. The main objective was directed to the clarification of crack growth behavior of LAS in high-temperature water due to EAC under constant load (steady-state power operation), to study the effect of transient conditions (during operation or start-up/shut-down of a plant) using their impact on time-based and cycle-based crack growth rates and to a more detailed understanding of the acting mechanisms. Autoclave tests were performed with Western and Russian type reactor pressure vessel steels under simulated boiling water reactor (BWR)/normal water chemistry (NWC) and pressurized water reactor (WWER) conditions. The investigations were performed with fracture mechanics specimens of different sizes and geometries. The applied loading comprised cyclic loads, static loads and load spectra where the static load was periodically interrupted by partial unloading. With regard to water chemistry, the oxygen content (WWER) and impurities of sulphate and chlorides (BWR) were varied beyond allowable limits for continuous operation. The current paper summarizes the most important crack growth results obtained under simulated WWER conditions. The influence of oxygen content and the effect of specimen size (C(T)25 versus C(T)50 specimens) on the crack growth rates are shown. The results are discussed in the context of the current crack growth rate curves in the corresponding nuclear codes. (authors)

  6. Implication of water phase condition on the K- and La- smectite-muscovite transition under high pressure and temperature

    Science.gov (United States)

    Conceicao, R. V.; Carniel, L. C.; Balzaretti, N. M.; Schenato, F.

    2013-12-01

    The lithospheric mantle is depleted in incompatible elements and basically anhydrous or nearly anhydrous, and can be rehydrated and re-enriched in these elements through subduction processes that brings, among others, pelagic material. In subduction zones, smectite is one of the most important minerals that could bring together water and trace elements into the mantle. However, in order to be considered efficient, smectite must resit to pressure and temperature or must transform into other phases able to bring such elements to the mantle and to release them in such condition. Our group is developing phase diagrams under high pressure and temperature (HPHT) in K- and La-doped smectite in order to understand the smectite-illite (or muscovite) transformation. Our results show that La-smectite is stable under pressures of 2.5GPa, 4.0 and 7.7GPa at temperatures up to 250°C, ~300°C and 350°C, respectively, above which they transform into a La-muscovite-like structure, being irreversible in such conditions. K-smectite, however, is stable at temperatures around 250° C, independently of any pressure. Above this temperature, it transforms into a I/S structure previously to changing into a muscovite structure at ~450°, 350° and ~300°C, under 2.5, 4.0 and 7.7GPa, respectively. These results show that pressure does not affect the stability of K-smectite, which remain stable up to 250°C under pressures up to 7.7GPa. On the other hand, higher pressures enlarge smoothly the La-smectite stability field in a very limited extension. Transformation of La-smectite into muscovite occurs directly, but K-smectite transformation occurs via I/S structure. When our results are compared to water/ice stability, we observe that La-smectite/La-muscovite transformation is in perfect agreement with high pressure ice/water transformation. Once ice became water, La-smectite became muscovite. However, K-smectite does not have such straightforward influence on ice/water transformation due to the existence of the I/S stability field.

  7. Boundary-Layer Separation Control under Low-Pressure Turbine Airfoil Conditions using Glow-Discharge Plasma Actuators

    Science.gov (United States)

    Hultgren, Lennart S.; Ashpis, David E.

    2003-01-01

    Modem low-pressure turbines, in general, utilize highly loaded airfoils in an effort to improve efficiency and to lower the number of airfoils needed. Typically, the airfoil boundary layers are turbulent and fully attached at takeoff conditions, whereas a substantial fraction of the boundary layers on the airfoils may be transitional at cruise conditions due to the change of density with altitude. The strong adverse pressure gradients on the suction side of these airfoils can lead to boundary-layer separation at the latter low Reynolds number conditions. Large separation bubbles, particularly those which fail to reattach, cause a significant degradation of engine efficiency. A component efficiency drop of the order 2% may occur between takeoff and cruise conditions for large commercial transport engines and could be as large as 7% for smaller engines at higher altitude. An efficient means of of separation elimination/reduction is, therefore, crucial to improved turbine design. Because the large change in the Reynolds number from takeoff to cruise leads to a distinct change in the airfoil flow physics, a separation control strategy intended for cruise conditions will need to be carefully constructed so as to incur minimum impact/penalty at takeoff. A complicating factor, but also a potential advantage in the quest for an efficient strategy, is the intricate interplay between separation and transition for the situation at hand. Volino gives a comprehensive discussion of several recent studies on transition and separation under low-pressure-turbine conditions, among them one in the present facility. Transition may begin before or after separation, depending on the Reynolds number and other flow conditions. If the transition occurs early in the boundary layer then separation may be reduced or completely eliminated. Transition in the shear layer of a separation bubble can lead to rapid reattachment. This suggests using control mechanisms to trigger and enhance early transition. Gad-el-Hak provides a review of various techniques for flow control in general and Volino discusses recent studies on separation control under low-pressure-turbine conditions utilizing passive as well as active devices. As pointed out by Volino, passive devices optimized for separation control at low Reynolds numbers tend to increase losses at high Reynolds numbers, Active devices have the attractive feature that they can be utilized only in operational regimes where they are needed and when turned off would not affect the flow. The focus in the present paper is an experimental Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modem low-pressure-turbine airfoil ('Pak-B'). The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) Gee-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface- flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control. of active separation control using glow discharge plasma actuators.

  8. Effect of media, additives, and incubation conditions on the recovery of high pressure and heat-injured Clostridium botulinum spores.

    Science.gov (United States)

    Reddy, N R; Tetzloff, R C; Skinner, G E

    2010-08-01

    The effect of additives and post-treatment incubation conditions on the recovery of high pressure and heat-injured (i.e., processed at 620 MPa and 95 and 100 degrees C for 5 min) spores of Clostridium botulinum strains, 62-A (proteolytic type A) and 17-B (nonproteolytic type B) was studied. High pressure and heat-injured spores were inoculated into TPGY (Trypticase-Peptone-Glucose-Yeast extract) anaerobic broth media containing additives (lysozyme, L-alanine, L-aspartic acid, dipicolonic acid, sodium bicarbonate, and sodium lactate) at various concentrations (0-10 microg/ml) individually or in combination. The spore counts of high pressure and heat-injured 62-A and 17-B recovered from TPGY broth containing lysozyme (10 microg/ml) incubated for 4 months versus that recovered from peptone-yeast extract-glucose-starch (PYGS) plating agar containing lysozyme (10 microg/ml) incubated under anaerobic conditions for 5 days were also compared. None of the additives either individually or in combination in TPGY broth improved recovery of injured spore enumeration compared to processed controls without additives. Addition of lysozyme at concentrations of 5 and 10 microg/ml in TPGY broth improved initial recovery of injured spores of 17-B during the first 4 days of incubation but did not result in additional recovery at the end of the 4 month incubation compared to the processed control without lysozyme. Adding lysozyme at a concentration of 10 microg/ml to PYGS plating agar resulted in no effect on the recovery of high pressure and heat-injured 62-A and 17-B spores. The recovery counts of high pressure and heat-injured spores of 62-A and 17-B were lower (i.e., agar compared to the MPN method using TPGY broth as the growth medium. PMID:20510779

  9. RCS pressure under reduced inventory conditions following a loss of residual heat removal

    International Nuclear Information System (INIS)

    The thermal-hydraulic response of a closed reactor coolant system to loss of residual heat removal (RHR) cooling is investigated. The processes examined include: core coolant boiling and steam generator reflux condensation, pressure increase on the primary side, heat transfer mechanisms on the steam generator primary and secondary sides, and effects of noncondensible gas on heat transfer processes.16 refs., 4 figs., 3 tabs

  10. Turbulence Sets the Initial Conditions for Star Formation in High-pressure Environments

    Science.gov (United States)

    Rathborne, J. M.; Longmore, S. N.; Jackson, J. M.; Kruijssen, J. M. D.; Alves, J. F.; Bally, J.; Bastian, N.; Contreras, Y.; Foster, J. B.; Garay, G.; Testi, L.; Walsh, A. J.

    2014-11-01

    Despite the simplicity of theoretical models of supersonically turbulent, isothermal media, their predictions successfully match the observed gas structure and star formation activity within low-pressure (P/k 107 K cm-3) environments, like those in the Galaxy's inner 200 pc central molecular zone (CMZ) and in the early universe. Here, we present Atacama Large Millimeter/submillimeter Array 3 mm dust continuum emission within a cloud, G0.253+0.016, which is immersed in the high-pressure environment of the CMZ. While the log-normal shape and dispersion of its column density probability distribution function (PDF) are strikingly similar to those of solar neighborhood clouds, there is one important quantitative difference: its mean column density is one to two orders of magnitude higher. Both the similarity and difference in the PDF compared to those derived from solar neighborhood clouds match predictions of turbulent cloud models given the high-pressure environment of the CMZ. The PDF shows a small deviation from log-normal at high column densities confirming the youth of G0.253+0.016. Its lack of star formation is consistent with the theoretically predicted, environmentally dependent volume density threshold for star formation which is orders of magnitude higher than that derived for solar neighborhood clouds. Our results provide the first empirical evidence that the current theoretical understanding of molecular cloud structure derived from the solar neighborhood also holds in high-pressure environments. We therefore suggest that these theories may be applicable to understand star formation in the early universe.

  11. Turbulence sets the initial conditions for star formation in high-pressure environments

    CERN Document Server

    Rathborne, J M; Jackson, J M; Kruijssen, J M D; Alves, J F; Bally, J; Bastian, N; Contreras, Y; Foster, J B; Garay, G; Testi, L; Walsh, A J

    2014-01-01

    Despite the simplicity of theoretical models of supersonically turbulent, isothermal media, their predictions successfully match the observed gas structure and star formation activity within low-pressure (P/k 10^7 K cm^-3) environments, like those in the Galaxy's inner 200 pc Central Molecular Zone (CMZ) and in the early Universe. Here we present ALMA 3mm dust continuum emission within a cloud, G0.253+0.016, which is immersed in the high-pressure environment of the CMZ. While the log-normal shape and dispersion of its column density PDF is strikingly similar to those of solar neighbourhood clouds, there is one important quantitative difference: its mean column density is 1--2 orders of magnitude higher. Both the similarity and difference in the PDF compared to those derived from solar neighbourhood clouds match predictions of turbulent cloud models given the high-pressure environment of the CMZ. The PDF shows a small deviation from log-normal at high column densities confirming the youth of G0.253+0.016. Its...

  12. Flare-out condition of Morris-Thorne wormhole and finiteness of pressure

    OpenAIRE

    Kim, Sung-Won

    2013-01-01

    Wormhole is defined as the topological structure with the throat connecting two asymptotically flat spaces. In order to have and maintain the structure of the wormhole, there needs the geometrical flare-out condition, i.e., the minimal size at throat. In the case of Morris-Thorne type wormhole, the condition is given by the huge surface tension compared to the energy density times the square of the light speed. In this paper, we re-considered the flare-out condition for the ...

  13. A new transducer for roll gap measurements of the roll pressure distribution and the friction condition in cold flat rolling

    DEFF Research Database (Denmark)

    Lagergren, Jonas; Wanheim, Tarras

    2005-01-01

    Background/purpose The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, this to overcome problems in previous measurements in the past 70 years. Method The new idea is to increase the contact surface of the transducer, to be larger than the arc of contact. This is in the opposite way, compared to the smaller and smaller contact pin design that has been prevailing. Results The measurements where conducted during cold dry rolling of both copper strips and stainless steel strips in a pilot mill. The recordings were selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. Conclusions The new transducer works very well, it was seen to be robust and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected by the authors and a good reproducibility, together with a proven agreement between recorded signals and signals simulated. Keywords Friction stress, normal pressure distribution, roll bite measurements, cold flat rolling of metals

  14. Effects of FeNi-phosphorus-carbon system on crystal growth of diamond under high pressure and high temperature conditions

    Science.gov (United States)

    Hu, Mei-Hua; Bi, Ning; Li, Shang-Sheng; Su, Tai-Chao; Zhou, Ai-Guo; Hu, Qiang; Jia, Xiao-Peng; Ma, Hong-An

    2015-03-01

    This paper reports the crystal growth of diamond from the FeNi–Carbon system with additive phosphorus at high pressures and high temperatures of 5.4–5.8 GPa and 1280–1360 °C. Attributed to the presence of additive phosphorus, the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the FeNi-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications. Project supported by the Doctoral Fund of Henan Polytechnic University, China (Grant Nos. B2013-013 and B2013-044) and the Research Projects of Science and Technology of the Education Department of Henan Province, China (Grant Nos. 14B430026 and 12A430010).

  15. Barometric effect in EAS with energies 1017-1019 eV

    International Nuclear Information System (INIS)

    Seasonal variations in extensive air showers (EAS) detected at the Yakut EAS array are analyzed. The atmospheric pressure dependence of the variations is essentially pronounced. As the pressure increases by 1 mm of mercury, the EAS intensity decreases by 2%. No air temperature dependence is revealed

  16. Preparation and calibration of pressure-sensitive and temperature-sensitive paints for fluorescence lifetime imaging applications

    OpenAIRE

    Stich, Matthias I. J.

    2010-01-01

    This thesis describes various methods for time-resolved luminescence lifetime determination, and their applications to imaging barometric pressure and temperature. These approaches are superior to luminescence intensity imaging in that they are less influenced by sources of errors like light scattering, inhomogeneous indicator distribution, photobleaching, or background fluorescence because they are intrinsically referenced. The data obtained are precise and unambiguous. Novel sensor material...

  17. Problems of investigation of HTGR fuel elements under loss-of-pressure accident conditions

    International Nuclear Information System (INIS)

    The conditions of operation of fuel elements in emergency situations with the depressurization of the primary circuit and air ingress the latter are discussed for the pebble bed module reactor. The analytical models of light and heavy corrosion of the fuel elements as well as the criterion conditions that determine the nature of corrosion are given. The local differentialities of surface corrosion of the fuel elements in the pebble bed with a natural convection of gas are evaluated. (author). 7 refs, 8 figs

  18. Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

    International Nuclear Information System (INIS)

    A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

  19. The application of the Buckingham theorem to modeling high-pressure regenerative heat exchangers in changed conditions

    Directory of Open Access Journals (Sweden)

    Rafal Marcin Laskowski

    2011-01-01

    Full Text Available Abstract The study presents the possibility of applying the Buckingham theorem to modeling high-pressure regenerative heat exchangers in changed conditions. A list of independent parameters on which the water temperature at the outlet of the heat exchanger depends was selected; and by means of the Buckingham theorem a functional relation between two dimensionless quantities, where there is no overall heat transfer coefficient, was obtained. The exact form of the function was determined on the basis of actual measurement data and a linear relation between two dimensionless quantities was obtained. The correctness of the proposed relation was examined for two high-pressure regenerative exchangers for a 200 MW power plant.

  20. A pressure correction scheme for generalized form of energy-stable open boundary conditions for incompressible flows

    Science.gov (United States)

    Dong, S.; Shen, J.

    2015-06-01

    We present a generalized form of open boundary conditions, and an associated numerical algorithm, for simulating incompressible flows involving open or outflow boundaries. The generalized form represents a family of open boundary conditions, which all ensure the energy stability of the system, even in situations where strong vortices or backflows occur at the open/outflow boundaries. Our numerical algorithm for treating these open boundary conditions is based on a rotational pressure correction-type strategy, with a formulation suitable for C0 spectral-element spatial discretizations. We have introduced a discrete equation and associated boundary conditions for an auxiliary variable. The algorithm contains constructions that prevent a numerical locking at the open/outflow boundary. In addition, we have developed a scheme with a provable unconditional stability for a sub-class of the open boundary conditions. Extensive numerical experiments have been presented to demonstrate the performance of our method for several flow problems involving open/outflow boundaries. We compare simulation results with the experimental data to demonstrate the accuracy of our algorithm. Long-time simulations have been performed for a range of Reynolds numbers at which strong vortices or backflows occur at the open/outflow boundaries. We show that the open boundary conditions and the numerical algorithm developed herein produce stable simulations in such situations.

  1. Predictions of Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions Using an Intermittency Transport Equation

    Science.gov (United States)

    Suzen, Y. B.; Huang, P. G.; Hultgren, Lennart S.; Ashpis, David E.

    2003-01-01

    A new transport equation for the intermittency factor was proposed to predict separated and transitional boundary layers under low-pressure turbine airfoil conditions. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, t , with the intermittency factor, y. Turbulent quantities are predicted by using Menter s two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model, which not only can reproduce the experimentally observed streamwise variation of the intermittency in the transition zone, but also can provide a realistic cross-stream variation of the intermittency profile. In this paper, the intermittency model is used to predict a recent separated and transitional boundary layer experiment under low pressure turbine airfoil conditions. The experiment provides detailed measurements of velocity, turbulent kinetic energy and intermittency profiles for a number of Reynolds numbers and freestream turbulent intensity conditions and is suitable for validation purposes. Detailed comparisons of computational results with experimental data are presented and good agreements between the experiments and predictions are obtained.

  2. Post-dryout heat transfer and entrained droplet sizes at low pressure and low flow conditions

    International Nuclear Information System (INIS)

    The entrainment mechanisms and the entrained droplet sizes with relation to the flow regimes are investigated. Through the analysis of many experimental post-dryout data, it is shown that the most probable flow regime near dryout or quench front is not annular flow but churn-turbulent flow when the mass flux is low. A correlation describing the initial droplet size just after the CHF position at low mass flux is suggested through regression analysis. The history-dependent post-dryout model of Varone and Rohsenow replaced by the Webb-Chen model for wall-vapor heat transfer is used as a reference model in the analysis. In the post-dryout region at low pressure and low flow, it is found that the suggested one-dimensional mechanistic model is not applicable when the vapor superficial velocity is very low. This is explained by the change of main entrainment mechanism with the change of flow regime. In bubbly or slug flow a number of tiny droplets generated from bubble burst become important in the heat transfer after dryout. Therefore, the suggested correlation is valid only in the churn-turbulent flow regime (jg* = 0.5?4.5). It is also suggested that the droplet size generated from the churn-turbulent surface is dependent not only on the pressure but also on the vapor velocity. It turns out that the present model can predict the measured cladding and vapor temperatures within 20% and 25%, respectively

  3. Exploring thermal and mechanical properties of selected transition elements under extreme conditions: Experiments at high pressures and high temperatures

    Science.gov (United States)

    Hrubiak, Rostislav

    Transition metals (Ti, Zr, Hf, Mo, W, V, Nb, Ta, Pd, Pt, Cu, Ag, and Au) are essential building units of many materials and have important industrial applications. Therefore, it is important to understand their thermal and physical behavior when they are subjected to extreme conditions of pressure and temperature. This dissertation presents: • An improved experimental technique to use lasers for the measurement of thermal conductivity of materials under conditions of very high pressure (P, up to 50 GPa) and temperature (T up to 2500 K). • An experimental study of the phase relationship and physical properties of selected transition metals, which revealed new and unexpected physical effects of thermal conductivity in Zr, and Hf under high P-T.. • New phase diagrams created for Hf, Ti and Zr from experimental data. • P-T dependence of the lattice parameters in ?-hafnium. Contrary to prior reports, the ?-? phase transition in hafnium has a negative dT/dP slope. • New data on thermodynamic and physical properties of several transition metals and their respective high P-T phase diagrams. • First complete thermodynamic database for solid phases of 13 common transition metals was created. This database has: All the thermochemical data on these elements in their standard state (mostly available and compiled); All the equations of state (EoS) formulated from pressure-volume-temperature data (measured as a part of this study and from literature); Complete thermodynamic data for selected elements from standard to extreme conditions. The thermodynamic database provided by this study can be used with available thermodynamic software to calculate all thermophysical properties and phase diagrams at high P-T conditions. For readers who do not have access to this software, tabulated values of all thermodynamic and volume data for the 13 metals at high P-T are included in the APPENDIX. In the APPENDIX, a description of several other high-pressure studies of selected oxide systems is also included. Thermophysical properties (Cp, H, S, G) of the high P-T ?-phase of Ti, Zr and Hf were determined during the optimization of the EoS parameters and are presented in this study for the first time. These results should have important implications in understanding hexagonal-close-packed to simple-hexagonal phase transitions in transition metals and other materials.

  4. Electrical safety equipment for pressurized water reactor power stations: insulation losses under accident conditions

    International Nuclear Information System (INIS)

    Thermodynamic conditions prevailing during the accidents examined often cause high insulation losses in K1 safety equipment located in the containment building. This article analyses the physical phenomena involved, gives examples of calculation of minimal insulation resistances which are necessary for the system operation and maximum insulation resistance required, indicates some rules for defining threshold values required in equipment qualification tests

  5. Experimental study on DNB heat flux of plate-type fuel in pressurized condition

    International Nuclear Information System (INIS)

    Experimental study was carried out in order to determine the DNB correlation for the safety analysis of the JMTR low enrichment fuel core. Since it is essential to examine applicability and safety margin of the correlation for the safety analysis, DNB heat fluxes were measured with the test section of rectangular flow channel simulating JMTR fuel element subchannel in the pressure range of 1 ? 13 kg/cm2 abs and the velocity range of 0 ? 4.4 m/s. Reviewing existed DNB correlations based on the experimental data, Sudo correlations scheme was selected for the JMTR safety analysis with minor modification for the high flow rate region. Comparing the correlations scheme with experimental data, allowable limit of the minimum DNBR was determined to be 1.5. (author)

  6. Pulsatile ex vivo perfusion of human saphenous vein grafts under controlled pressure conditions increases MMP-2 expression

    Science.gov (United States)

    2011-01-01

    Background The use of human saphenous vein grafts (HSVGs) as a bypass conduit is a standard procedure in the treatment of coronary artery disease while their early occlusion remains a major problem. Methods We have developed an ex vivo perfusion system, which uses standardized and strictly controlled hemodynamic parameters for the pulsatile and non-static perfusion of HSVGs to guarantee a reliable analysis of molecular parameters under different pressure conditions. Cell viability of HSVGs (n = 12) was determined by the metabolic conversion of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) into a purple formazan dye. Results Under physiological flow rates (10 mmHg) HSVGs remained viable for two weeks. Their exposure to arterial conditions (100 mmHg) was possible for one week without important reduction in viability. Baseline expression of matrix metalloproteinase-2 (MMP-2) after venous perfusion (2.2 ± 0.5, n = 5) was strongly up-regulated after exposure to arterial conditions for three days (19.8 ± 4.3) or five days (23.9 ± 6.1, p < 0.05). Zymographic analyses confirmed this increase on the protein level. Our results suggest that expression and activity of MMP-2 are strongly increased after exposure of HSVGs to arterial hemodynamic conditions compared to physiological conditions. Conclusion Therefore, our system might be helpful to more precisely understand the molecular mechanisms leading to an early failure of HSVGs. PMID:21777461

  7. A model for calculation of RCS pressure during reflux boiling under reduced inventory conditions and its assessment against PKL data

    International Nuclear Information System (INIS)

    There has been recent interest in the United States concerning the loss of residual heat removal system (RHRS) under reduced coolant inventory conditions for pressurized water reactors. This issue is also of interest in the Federal Republic of Germany and an experiment was performed in the integral PKL-HI experimental facility at Siemens-KWU to supply applicable data. Recently, an NRC-sponsored effort has been undertaken at the Idaho-National Engineering Laboratory to identify and analyze the important thermal-hydraulic phenomena in pressurized water reactors following the long term loss-of-RHRS during reduced inventory operation. The thermal-hydraulic response of a closed reactor coolant system during such a transient is investigated in this report. Some of the specific processes investigated include: reflux condensation in the steam generators, the corresponding pressure increase in the reactor coolant system, and void fraction distributions on the primary side of the system. Mathematical models of these and other physical processes Experiment B4.5

  8. Slug behavior and pressure drop of adiabatic slug flow in a narrow rectangular duct under inclined conditions

    International Nuclear Information System (INIS)

    Highlights: • The effect of inclination on distribution parameter and drift velocity is studied. • Slug behaviors in different flow regions are investigated. • Inclination influences the void fraction and slip ratio. • Drift flux models for calculating void fraction are evaluated. • Correlations of frictional pressure drop are evaluated in different flow regions. - Abstract: A visualization-based investigation was carried out on slug behavior and pressure drop of air–water slug flow in a narrow rectangular duct with cross section of 43 mm × 3.25 mm under inclined conditions. The velocity and length of slugs were obtained through image processing. Based on the liquid Reynolds number, slug flow was divided into laminar flow region (Rel l ? 3000). Experimental results showed that both the slug velocity and the slug length increased with the inclination angle increasing in laminar flow region, while they were nearly unvaried in turbulent flow region. The slug length and slug frequency decreased with the gas superficial velocity increasing or the liquid superficial velocity decreasing for all cases. For laminar flow, the predictions of frictional pressure drop by Chisholm model, Mishima–Hibiki correlation and Lee–Lee correlation could be significantly improved by replacing the void fraction with the ratio of the slug velocity divided by the gas superficial velocity, us/jg; for turbulent region, all three models could well predict the experimental data if void fraction is calculated by the Jones–Zuber correlation

  9. Influence of the external conditions on salt retention and pressure-induced electrical potential measured across a composite membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1999-01-01

    Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence on these parameters of different external conditions due to hydrodynamic or chemical changes in the feed solutions was also studied. Changes were carried out by variation of the feed solution velocity (Reynolds numbers between 1500 and 3300) or the concentration ratio of mixed electrolytes (r = HCl/NaCl and HCl/MgCl2, r = 1, 0.5 and 0.1), respectively. Results show that J(v), S and Delta E values slightly increase when the velocity of the feed solution increases, but the mixed electrolytes strongly affect both salt rejection and pressure-induced electrical potential. A change in the sign of both parameters with respect to the value determined with single electrolytes at the same concentration was obtained, which is attributed to a strong coupling among the fluxes of individual ions and their distribution in the membrane when transport of mixed salt is studied. (C) 1999 Elsevier Science B.V. All rights reserved.

  10. Simulation and analysis of bearing pad to pressure tube contact heat transfer under large break LOCA conditions

    International Nuclear Information System (INIS)

    In some postulated loss-of-coolant accidents (LOCAs) in a CANDU reactor, localized 'hot spots' can develop on the pressure tube as a result of decay heat dissipation by conduction through bearing pad/pressure tube contact locations. Depending on the severity of flow degradation in the channel, these 'hot spots' could represent a potential threat to fuel channel integrity. The most important parameter in the simulation of BP/PT contact is the contact conductance. Since BP/PT thermal contact conductance is a complex parameter which depends upon the thermal and physical characteristics of the material junction and the surrounding environment, contact conductance is determined from experiments relevant to the reactor conditions. A series of twelve full scale integrated BP/PT contact experiments have been conducted at AECL-WRL under CANDU Owner Group (COG). The objective of the experiments was to investigate the effect of BP/PT contact on PT thermal-mechanical behaviour. This paper presents the simulation of BP/PT interaction integrated experiments using SMARTT and MINI-SMARTT computer codes and subsequent derivation of the BP/PT contact conductance by best fitting of the experimental pressure tube temperature measurements. (author)

  11. Meshfree finite differences for vector Poisson and pressure Poisson equations with electric boundary conditions

    OpenAIRE

    Zhou, Dong; Seibold, Benjamin; Shirokoff, David; Chidyagwai, Prince; Rosales, Rodolfo Ruben

    2013-01-01

    We demonstrate how meshfree finite difference methods can be applied to solve vector Poisson problems with electric boundary conditions. In these, the tangential velocity and the incompressibility of the vector field are prescribed at the boundary. Even on irregular domains with only convex corners, canonical nodal-based finite elements may converge to the wrong solution due to a version of the Babuska paradox. In turn, straightforward meshfree finite differences converge to...

  12. Morphological variations in AuxSiy nanostructures under variable pressure and annealing conditions

    Science.gov (United States)

    Rath, A.; Dash, J. K.; Juluri, R. R.; Satyam, P. V.

    2015-03-01

    Well-ordered, substrate symmetry-driven, AuxSiy structures of average size ~25 nm were formed under ultra-high vacuum (UHV) conditions using molecular beam epitaxy method. Post-annealing was done at 500 °C in three different vacuum conditions: (1) low vacuum (LV) (10-2 mbar), (2) high vacuum (HV) (10-5 mbar) and (3) UHV (10-10 mbar) (MBE chamber). For both HV and LV cases, the AuxSiy nanostructures were found to have their corners rounded unlike in UHV case where the structures have sharp edges. In all the above three cases, samples were exposed to air before annealing. In situ annealing inside UHV chamber without exposing to air resulted in well-aligned rectangles with sharp corners, while sharp but irregular island structures were found for air exposed and UHV annealing system. The role of residual gases present in LV and HV annealing environment and inhibition of lateral surface diffusion due to the presence of surface oxide (through air exposure) would be discussed. Annealing at various conditions yielded variation in the coverage and correspondingly, the average area of nanostructures varied from a ~329 nm2 (as deposited) to ~2,578 nm2 (at high temperature). High-resolution transmission electron microscopy (planar and cross section) has been utilized to study the morphological variations.

  13. A model for calculation of RCS pressure during reflux boiling under reduced inventory conditions and its assessment against PKL data

    International Nuclear Information System (INIS)

    Based on the occurrence of a number of plant incidents during low power and shutdown operating conditions, the Nuclear Regulatory Commission (NRC) has initiated several programs to better quantify risk during these periods. One specific issue of interest is the loss of residual heat removal (RHR) under reduced coolant inventory conditions. This issue is also of interest in the Federal Republic of Germany and an experiment was performed in the integral PKL-3 experimental facility at Siemens-KWU to supply applicable data. Recently, an effort has been undertaken at the Idaho National Engineering Laboratory (INEL) to identify and analyze the important thermal-hydraulic phenomena in pressurized water reactors following loss of vital AC power and consequent loss of the RHR system during reduced inventory operation. The thermal-hydraulic response of a nuclear steam supply system (NSSS) with a closed reactor coolant system (RCS) to loss of residual heat removal cooling capability is investigated in this report. The specific processes investigated include: boiling of the coolant in the core and reflux condensation in the steam generators, the corresponding pressure increase in the reactor coolant system, the heat transfer mechanisms on the primary and secondary sides of the steam generators, the effects of air or other noncondensible gas on the heat transfer processes, and void fraction distributions on the primary side of the system. Mathematical models of these physical processes were developed and validated against experimental data from the PKL 3B 4.5 Experiment

  14. Critical heat flux for uniformly heated rod bundle under high-pressure, low-flow and mixed inlet conditions

    International Nuclear Information System (INIS)

    Dryout experiments have been conducted in a 5 x 5 rod bundle under high-pressure, low-flow and mixed inlet conditions which are of importance in the core thermal-hydraulic behavior during a loss-of-coolant accident (LOCA) of a nuclear reactor. The experimental conditions cover ranges of pressure from 3 to 12 MPa, mass flux from 20 to 410 kg/m2·s and inlet quality from 0 4 to 0 9. The dryout data have been compared with several empirical critical heat flux (CHF) correlations that are commonly used to predict CHF behavior and with an equation derived on basis of a simple assumption. The Biasi correlation overpredicts considerably the CHF; in some cases, it overpredicts the CHF by a factor of 10 or 100. The Bowring correlation underpredicts the CHF to approximately 1/2. The Katto correlation performs relatively well in correlating the present dryout data. An equation derived on basis of a simple assumption that dryout occurs due to complete vaporization of liquid in a subchannel performs best among the correlations examined in predicting the present dryout data. (author)

  15. The ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions

    International Nuclear Information System (INIS)

    To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions

  16. Current Pressure Transducer Application of Model-based Prognostics Using Steady State Conditions

    Science.gov (United States)

    Teubert, Christopher; Daigle, Matthew J.

    2014-01-01

    Prognostics is the process of predicting a system's future states, health degradation/wear, and remaining useful life (RUL). This information plays an important role in preventing failure, reducing downtime, scheduling maintenance, and improving system utility. Prognostics relies heavily on wear estimation. In some components, the sensors used to estimate wear may not be fast enough to capture brief transient states that are indicative of wear. For this reason it is beneficial to be capable of detecting and estimating the extent of component wear using steady-state measurements. This paper details a method for estimating component wear using steady-state measurements, describes how this is used to predict future states, and presents a case study of a current/pressure (I/P) Transducer. I/P Transducer nominal and off-nominal behaviors are characterized using a physics-based model, and validated against expected and observed component behavior. This model is used to map observed steady-state responses to corresponding fault parameter values in the form of a lookup table. This method was chosen because of its fast, efficient nature, and its ability to be applied to both linear and non-linear systems. Using measurements of the steady state output, and the lookup table, wear is estimated. A regression is used to estimate the wear propagation parameter and characterize the damage progression function, which are used to predict future states and the remaining useful life of the system.

  17. Farmers Under Pressure : Analysis of the Social Conditions of Cases of Animal Neglect

    DEFF Research Database (Denmark)

    Andrade, Stefan Bastholm; Anneberg, Inger

    2014-01-01

    In this paper we analyse how risk factors in highly industrialised agriculture are connected to animal neglect. With Danish agriculture as a case study, we use two types of data. First, we use register data from Statistics Denmark to map how risk factors such as farmers’ financial and social troubles are connected to convictions of neglect. Second, we analyse narratives where interviewed farmers, involved in cases of neglect, describe how they themselves experienced the incidents. We find that while livestock farmers in general have a low risk of animal neglect problems, a small percentage of them face severe financial difficulties, divorce and psychiatric problems, which are connected to an increased risk of being convicted for the neglect of farm animals. The narratives bring forward themes of pressure related to financial trouble, technological break down, family problems, stress and a growing concern among the farmers towards the governmental control in farm animal production. We discuss how these factorscan be used to identify and help farmers with a high risk of being convicted of livestock neglect.

  18. Preliminary Testing of a Pressurized Space Suit and Candidate Fabrics Under Simulated Mars Dust Storm and Dust Devil Conditions

    Science.gov (United States)

    Gaier, James R.; deLeon, Pablo G.; Lee, Pascal; McCue, Terry R.; Hodgson, Edward W.; Thrasher, Jeff

    2010-01-01

    In August 2009 YAP Films (Toronto) received permission from all entities involved to create a documentary film illustrating what it might be like to be on the surface of Mars in a space suit during a dust storm or in a dust devil. The science consultants on this project utilized this opportunity to collect data which could be helpful to assess the durability of current space suit construction to the Martian environment. The NDX-1 prototype planetary space suit developed at the University of North Dakota was used in this study. The suit features a hard upper torso garment, and a soft lower torso and boots assembly. On top of that, a nylon-cotton outer layer is used to protect the suit from dust. Unmanned tests were carried out in the Martian Surface Wind Tunnel (MARSWIT) at the NASA Ames Research Center, with the suit pressurized to 10 kPa gauge. These tests blasted the space suit upper torso and helmet, and a collection of nine candidate outer layer fabrics, with wind-borne simulant for five different 10 min tests under both terrestrial and Martian surface pressures. The infiltration of the dust through the outer fabric of the space suit was photographically documented. The nine fabric samples were analyzed under light and electron microscopes for abrasion damage. Manned tests were carried out at Showbiz Studios (Van Nuys, California) with the pressure maintained at 20 2 kPa gauge. A large fan-created vortex lifted Martian dust simulant (Fullers Earth or JSC Mars-1) off of the floor, and one of the authors (Lee) wearing the NDX-1 space suit walked through it to judge both subjectively and objectively how the suit performed under these conditions. Both the procedures to scale the tests to Martian conditions and the results of the infiltration and abrasion studies will be discussed.

  19. Geochemistry of ultrahigh-pressure anatexis: fractionation of elements in the Kokchetav gneisses during melting at diamond-facies conditions

    Science.gov (United States)

    Stepanov, Aleksandr S.; Hermann, Joerg; Korsakov, Andrey V.; Rubatto, Daniela

    2014-05-01

    The Kokchetav complex in Kazakhstan contains garnet-bearing gneisses that formed by partial melting of metasedimentary rocks at ultrahigh-pressure (UHP) conditions. Partial melting and melt extraction from these rocks is documented by a decrease in K2O and an increase in FeO + MgO in the restites. The most characteristic trace element feature of the Kokchetav UHP restites is a strong depletion in light rare earth elements (LREE), Th and U. This is attributed to complete dissolution of monazite/allanite in the melt and variable degree of melt extraction. In contrast, Zr concentrations remain approximately constant in all gneisses. Using experimentally determined solubilities of LREE and Zr in high-pressure melts, these data constrain the temperature of melting to ~1,000 °C. Large ion lithophile elements (LILE) are only moderately depleted in the samples that have the lowest U, Th and LREE contents, indicating that phengite retains some LILE in the residue. Some restites display an increase in Nb/Ta with respect to the protolith. This further suggests the presence of phengite, which, in contrast to rutile, preferentially incorporates Nb over Ta. The trace element fractionation observed during UHP anatexis in the Kokchetav gneisses is significantly different from depletions reported in low-pressure restites, where generally no LREE and Th depletion occurs. Melting at UHP conditions resulted in an increase in the Sm/Nd ratio and a decoupling of the Sm-Nd and Lu-Hf systems in the restite. Further subduction of such restites and mixing with mantle rocks might thus lead to a distinct isotopic reservoir different from the bulk continental crust.

  20. Influence of welding and annealing conditions on the mechanical-technological characteristics of welded joints in high-strength pressure vessel steels. Pt. A

    International Nuclear Information System (INIS)

    In welding hight-strength pressure vessel steels, formation of cold cracks and cracks during stress relief annealing can be prevented. The behaviour of different materials with regard to crack formation is outlined. The necessary measures to avoid welding flows are described. The toughness to be explained for some differently alloyed pressure vessel steels in connection with welding conditions and metallurgical processes. (orig.)

  1. Simulation of ATWS conditions in pressurized water reactors; Simulation von ATWS-Transienten in Druckwasserreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Kliem, Soeren; Mittag, Siegfried; Rohde, Ulrich; Grundmann, Ulrich; Weiss, Frank-Peter [Forschungszentrum Dresden-Rossendorf, Dresden (Germany). Inst. fuer Sicherheitsforschung

    2009-02-15

    Safety analyses of nuclear power plants use ATWS (Anticipated Transients without Scram) as a term covering also events involving assumed failure of the reactor scram system. In this type of failure of the reactor scram system, power development in the reactor core is determined only by neutron kinetics feedback via the fuel temperature, moderator temperature and moderator density. If borated coolant is supplied, there is the additional feedback from the boron concentration. For nuclear power plants, coupled code complexes are developed and used which are made up of a thermohydraulic plant code and a 3D neutron kinetics model of the reactor core. These lend themselves to the use in analyses of ATWS states. The work presented here about the ATWS problem was performed in the interest of a consistent application of the DYN3D 3D neutron kinetics code in combination with the ATHLET thermohydraulic system code, and the quantification of differences resulting from variations of initial and boundary conditions. The DYN3D/ATHLET coupled code complex was validated by recalculation of various operating transients and by solving benchmark problems. The article contains results computed taking into account the influence of systems engineering and neutron kinetics boundary conditions. The calculations shown are methodological studies in no way demonstrating proof. (orig.)

  2. Sorption activity investigation of ultrafine powders of high temperature melting point compounds in atmospheric pressure conditions

    International Nuclear Information System (INIS)

    A study is made in saturation with gas in the air for ultradispersed chromium carbonitride and boride powders synthesized in a nitrogen plasma jet according to three variants: from elements, from oxides, from chromium trichloride. It is established that in the air on temperature increasing the powders adsorb considerable amounts of oxygen and water vapor. This results in surface oxidation of powder particles and a loss in specific combination of properties. Preliminary vacuum heat treatment is shown to decrease sharply the rate of atmospheric gas adsorption. The quantity of adsorbed gases is dependent on a carbon monoxide concentration in a particle surface layer and the availability of adsorption centers. The number of such centers in the layer can be controlled by vacuum heat treatment conditions. The interaction of the powders with atmospheric gases is concluded to be of adsorption-diffusion nature

  3. State of the art on the heat transfer experiments under supercritical pressure condition

    International Nuclear Information System (INIS)

    The SCWR(Super-Critical Water cooled Reactor) is one of the six reactor candidates selected in the Gen-IV project which aims at the development of new reactors with enhanced economy and safety. The SCWR is considered to be a feasible concept of new nuclear power plant if the existing technologies developed in fossil fuel fired plant and LWR technologies together with additional research on several disciplines such as materials, water chemistry and safety. As KAERI takes part in the GIF(Generation IV Forum) for the Gen-IV project, domestic concerns about the SCWR have been recently increased. In order to establish a foundation for the development of SCWR, efforts should be concentrated on the conceptual design of systems and the associated key experiments as well. Heat transfer experiments, among others, under supercritical condition are required for the proper prediction of thermal hydraulic phenomena, which are essential for the thermal hydraulic designs of reactor core. Nevertheless, the experiments have not been performed in Korea yet. This report deals with fundamental surveys on the heat transfer experiments under supercritical conditions, which are required for the understanding of heat transfer characteristics for the thermal hydraulic designs of supercritical reactor core. Investigations on the physical properties of water and CO2 showed that the physical properties such as density, specific heat, viscosity and thermal conductivity are significantly changed near the pseudo-critical points. The state of the art on the heat transfer characteristics in relation with heat transfer deterioration and heat transfer coefficient is briefly described. In addition, previous experiments with supercritical water as well as supercritical CO2 and Freon used for an alternating fluid are presented

  4. A standalone decay heat removal device for the Gas-cooled Fast Reactor for intermediate to atmospheric pressure conditions

    International Nuclear Information System (INIS)

    Highlights: ? An analytical model predicting Brayton cycle off-design steady states, is developed. ? The model is used to design an autonomous decay heat removal system for the GFR. ? Predictions of the analytical model are verified using CATHARE. ? CATHARE code is used to simulate a set of GFR safety depressurization transients using this device. ? Convenient turbo-machine designs exist for the targeted autonomous decay heat removal for a wide pressure range. - Abstract: This paper reports a design study for a Brayton cycle machine, which would constitute a dedicated, standalone decay heat removal (DHR) device for the Generation IV Gas-cooled Fast Reactor (GFR). In comparison to the DHR reference strategy developed by the French Commissariat à l’Energie Atomique during the GFR pre-conceptual design phase (which was completed at the end of 2007), the salient feature of this alternative device would be to combine the energetic autonomy of the natural convection process – which is foreseen for operation at high and medium pressures – with the efficiency of the forced convection process which is foreseen for operation down to very low pressures. An analytical model, the so-called “Brayton scoping model”, is described first. This is based on simplified thermodynamic and aerodynamic equations, and was developed to highlight design choices. Two different machine designs are analyzed: a Brayton loop turbo-machine working with helium, and a second one wor and a second one working with nitrogen, since nitrogen is the heavy gas foreseen to be injected into the primary system to enhance the natural convection under loss-of-coolant-accident (LOCA) conditions. Simulations of the steady-state and transient behavior of the proposed device have then been carried out using the CATHARE code. These serve to confirm the insights obtained from usage of the “Brayton scoping” model, e.g., that the turbo-machine conveniently accelerates during the depressurization process to tend towards a steady rotational speed value, the speed rise being inversely proportional to the experienced pressure drop. Finally, CATHARE simulations are presented for complete DHR scenarios for the GFR, involving loss-of-coolant-accidents (LOCAs) in conjunction with loss of back-up-pressure (LOBP). Thereby, it is shown that, in each of the investigated cases, incorporation of the Brayton loop turbo-machine with nitrogen indeed leads to fuel temperatures remaining considerably below Category 4 accident limits.

  5. Mineralogical studies on alteration of barium borosilicate nuclear waste glass under accelerated pressure temperature conditions

    International Nuclear Information System (INIS)

    Silicate glass is thermodynamically unstable material hence its dissolution leads to the solubility of glass components, often accompanied by the formation of secondary amorphous gels at low temperatures. Rate of silicate glass dissolution often decreases appreciably as the concentration of silicic acid increases in the solution. Understanding of glass reactions with the environment is required to predict long-term glass dissolution mechanism and rate of radionuclide release in the geological repository. An inactive barium borosilicate glass (reference material for vitrified nuclear waste) was subjected to laboratory induced near hydrothermal conditions at various temperatures ranging between 100 to 300 deg C for different time intervals. Leachates obtained were studied to understand solution chemistry and solubility products of glass dissolution kinetics and the retention of elements. The surface chemistry and morphology of the specimens were studied using XRD and SEM-EDS. The scanning electron microscopic study on the surface of the treated specimens indicates formation of multiple alteration layers as well as secondary products such as smectite, hydrotalcite and saponite. For barium borosilicate glass three material types were distinguished - (a) initial stage of glass dissolution, (b) thin coatings of altered glass which envelope glass grains and (c) thick crust of coalescing alteration products, formed on top of the glass grains. The needle shaped spherulite like grains. The needle shaped spherulite like Si particles adhering to the grains were also found, but without the crust

  6. Electrochemical promotion of catalytic ethylene oxidation on Pt/YSZ catalyst under low pressure conditions

    International Nuclear Information System (INIS)

    The catalytic oxidation of C2H4 on Pt catalyst film interfaced with the oxygen-ion conducting yttria-stabilized zirconia solid electrolyte (YSZ) has been studied in the 10-5 and 10-4 mbar range. Photoemission electron microscopy (PEEM) was used as spatially resolving method. Under open circuit conditions (VWR=0 V) the CO2 production increases by rising p(C2H4) and then at a critical point decreases sharply, showing a pronounced hysteresis. The hysteresis and the abrupt rate decrease are attributed to the build-up of a carbonaceous CHx layer inhibiting O2 adsorption and hence poisoning the catalyst. Applying an anodic potential of +1V leads to trigger a transition from the unreactive branch of the reaction to an active branch. The huge non-Faradayicity reported in the literature for this reaction system is explained as an ignition effect caused by the partial removal of the inhibiting carbonaceaous layer. The electrode has been characterized by SEM, XRD and a profilometer.

  7. An assessment of the failure rate for the beltline region of PWR pressure vessels during normal operation and certain transient conditions. Technical report

    International Nuclear Information System (INIS)

    A study was conducted to assess the failure rate for the beltline region of a generic pressurized-water reactor (PWR) pressure vessel. This assessment included the evaluation of several normal operating and transient reactor conditions. Failure rates were calculated from a computer code that used fracture mechanics methods to model the failure process; random number generation techniques were used to simulate random variables and model their interaction in the failure-process. This investigation had three major objectives: (1) to better define the effect of neutron irradiation, material variation, and flaw distribution on the failure rate for the beltline region of PWR pressure vessels, (2) to estimate the relative margins against failure for normal operation and certain transient conditions associated with nuclear pressure vessels, and (3) to evaluate the current limitations for using fracture mechanics models to predict failure rates for nuclear pressure vessels

  8. In situ Evidence of Breaking the Ion Frozen-in Condition via the Non-gyrotropic Pressure Effect in Magnetic Reconnection

    CERN Document Server

    Dai, Lei; Angelopoulos, Vassilis; Glassmeier, Karl-Heinz

    2015-01-01

    For magnetic reconnection to proceed, the frozen-in condition for both ion fluid and electron fluid in a localized diffusion region must be violated by inertial effects, thermal pressure effects, or inter-species collisions. It has been unclear which underlying effects unfreeze ion fluid in the diffusion region. By analyzing in-situ THEMIS spacecraft measurements at the dayside magnetopause, we present clear evidence that the off-diagonal components of the ion pressure tensor is mainly responsible for breaking the ion frozen-in condition in reconnection. The off-diagonal pressure tensor, which corresponds to a nongyrotropic pressure effect, is a fluid manifestation of ion demagnetization in the diffusion region. From the perspective of the ion momentum equation, the reported non-gyrotropic ion pressure tensor is a fundamental aspect in specifying the reconnection electric field that controls how quickly reconnection proceeds.

  9. Pulsatile ex vivo perfusion of human saphenous vein grafts under controlled pressure conditions increases MMP-2 expression

    Directory of Open Access Journals (Sweden)

    Lange Rüdiger

    2011-07-01

    Full Text Available Abstract Background The use of human saphenous vein grafts (HSVGs as a bypass conduit is a standard procedure in the treatment of coronary artery disease while their early occlusion remains a major problem. Methods We have developed an ex vivo perfusion system, which uses standardized and strictly controlled hemodynamic parameters for the pulsatile and non-static perfusion of HSVGs to guarantee a reliable analysis of molecular parameters under different pressure conditions. Cell viability of HSVGs (n = 12 was determined by the metabolic conversion of 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl-tetrazolium bromide (MTT into a purple formazan dye. Results Under physiological flow rates (10 mmHg HSVGs remained viable for two weeks. Their exposure to arterial conditions (100 mmHg was possible for one week without important reduction in viability. Baseline expression of matrix metalloproteinase-2 (MMP-2 after venous perfusion (2.2 ± 0.5, n = 5 was strongly up-regulated after exposure to arterial conditions for three days (19.8 ± 4.3 or five days (23.9 ± 6.1, p Conclusion Therefore, our system might be helpful to more precisely understand the molecular mechanisms leading to an early failure of HSVGs.

  10. Corrosion fatigue crack growth behaviour of low-alloy reactor pressure vessel steels under boiling water reactor conditions

    International Nuclear Information System (INIS)

    The corrosion fatigue crack growth behaviour of different low-alloy reactor pressure vessel (RPV) steels and weld filler/heat-affected zone materials was systematically characterized under simulated boiling water reactor normal water and hydrogen water chemistry conditions by low-frequency fatigue tests with pre-cracked fracture mechanics specimens. The experiments were performed in oxygenated or hydrogenated high-purity or sulphate/chloride containing water at temperatures from 150 to 288 deg. C. In this paper, the observed synergistic effects of environmental, material and loading parameters on the environmental acceleration of fatigue crack growth in low-alloy RPV steels are discussed in the context of the Ford-Andresen model. Additionally, the adequacy and conservatism of the current 'ASME XI reference fatigue crack growth curves' of the ASME Boiler and Pressure Vessel Code are critically reviewed and assessed on the basis of the gathered experimental data base and this model. Based on the observed cracking behaviour and the Ford-Andresen model, a simple time-domain superposition model is suggested, which could reduce most of the undue conservatism and eliminate uncertainties of the existing codes and therefore serve as a basis for the development of improved reference fatigue crack growth curves

  11. Measurement of the growth kinetics of cracks in bainitic NPP pressure vessel steel under stress corrosion cracking conditions

    International Nuclear Information System (INIS)

    To evaluate the possibility of stable crack growth in the reactor pressure vessel wall due to the stress corrosion cracking (SCC) mechanism and as well as to calculate the life time of the pressure vessel, the kinetics of the crack growth should be evaluated. The paper deals with the comparison between the behaviour of small and large cracks from the point of view of SCC. The material 15Kh2NMFAA used for the WWER-type RPVs, as the base material, was chosen for the experiments. Slow strain rate tests are carried out on tensile specimens to evaluate the kinetics of small environmentally -initiated cracks. The slow displacement rate are applied to CT specimens is used to evaluate the kinetics of large pre-existing cracks. To compare the response to different water chemistry conditions, tests have been carried out in WWER primary circuit environment with low (below 20 ppb) and high (higher that 1 ppm) dissolved oxygen (DO) content. All the tests have been done in through-flow autoclave system with controlled water chemistry. (author)

  12. Multiwell CO2 injectivity: impact of boundary conditions and brine extraction on geologic CO2 storage efficiency and pressure buildup.

    Science.gov (United States)

    Heath, Jason E; McKenna, Sean A; Dewers, Thomas A; Roach, Jesse D; Kobos, Peter H

    2014-01-21

    CO2 storage efficiency is a metric that expresses the portion of the pore space of a subsurface geologic formation that is available to store CO2. Estimates of storage efficiency for large-scale geologic CO2 storage depend on a variety of factors including geologic properties and operational design. These factors govern estimates on CO2 storage resources, the longevity of storage sites, and potential pressure buildup in storage reservoirs. This study employs numerical modeling to quantify CO2 injection well numbers, well spacing, and storage efficiency as a function of geologic formation properties, open-versus-closed boundary conditions, and injection with or without brine extraction. The set of modeling runs is important as it allows the comparison of controlling factors on CO2 storage efficiency. Brine extraction in closed domains can result in storage efficiencies that are similar to those of injection in open-boundary domains. Geomechanical constraints on downhole pressure at both injection and extraction wells lower CO2 storage efficiency as compared to the idealized scenario in which the same volumes of CO2 and brine are injected and extracted, respectively. Geomechanical constraints should be taken into account to avoid potential damage to the storage site. PMID:23971876

  13. DNS study of the ignition of n-heptane fuel spray under high pressure and lean conditions

    International Nuclear Information System (INIS)

    Direct numerical simulations (DNS) are used to investigate the ignition of n-heptane fuel spray under high pressure and lean conditions. For the solution of the carrier gas fluid, the Eulerian method is employed, while for the fuel spray, the Lagrangian method is used. A chemistry mechanism for n-heptane with 33 species and 64 reactions is adopted to describe the chemical reactions. Initial carrier gas temperature and pressure are 926 K and 30.56 atmospheres, respectively. Initial global equivalence ratio is 0.258. Two cases with droplet radiuses of 35.5 and 20.0 macrons are simulated. Evolutions of the carrier gas temperature and species mass fractions are presented. Contours of the carrier gas temperature and species mass fractions near ignition and after ignition are presented. The results show that the smaller fuel droplet case ignites earlier than the larger droplet case. For the larger droplet case, ignition occurs first at one location; for the smaller droplet case, however, ignition occurs first at multiple locations. At ignition kernels, significant NO is produced when temperature is high enough at the ignition kernels. For the larger droplet case, more NO is produced than the smaller droplet case due to the inhomogeneous distribution and incomplete mixing of fuel vapor

  14. Field-emitting Townsend regime of surface dielectric barrier discharges emerging at high pressure up to supercritical conditions

    Science.gov (United States)

    Pai, David Z.; Stauss, Sven; Terashima, Kazuo

    2015-04-01

    Surface dielectric barrier discharges (DBDs) in CO2 from atmospheric pressure up to supercritical conditions generated using 10 kHz ac excitation are investigated experimentally. Using current–voltage and charge–voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy, we identify and characterize a field-emitting Townsend discharge regime that emerges above 0.7 MPa. An electrical model enables the calculation of the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The space-averaged Laplacian field is accounted for in the circuit model by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are demonstrated to fit the description of atmospheric-pressure Townsend DBDs (Naudé et al 2005 J. Phys. D: Appl. Phys. 38 530–8), i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron–neutral bremsstrahlung corresponding to an average electron temperature of 2600 K. Raman spectra of CO2 near the critical point demonstrate that the average gas temperature increases by less than 1 K.

  15. Low-temperature rupture behavior of Zircaloy-clad pressurized water reactor spent fuel rods under dry storage conditions

    International Nuclear Information System (INIS)

    Creep rupture studies on five well-characterized Zircaloy-clad pressurized water reactor spent fuel rods, which were pressurized to a hoop stress of about145 MPa, were conducted for up to 2101 h at 3230C. The conditions were chosen for limited annealing of in-reactor irradiation hardening. No cladding breaches occurred, although significant hydride agglomeration and reorientation took place in rods that cooled under stress. Observations are interpreted in terms of a conservatively modified Larson-Miller curve to provide a lower bound on permissible maximum dry-storage temperatures, assuming creep rupture as the life-limiting mechanism. If hydride reorientation can be ruled out during dry storage, 3050C is a conservative lower bound, based on the creep-rupture mechanism, for the maximum storage temperature of rods with irradiation-hardened cladding to ensure a 100-yr cladding lifetime in an inert atmosphere. An oxidizing atmosphere reduced the lower bound on the maximum permissible storage temperature by about50C. While this lower bound is based on whole-rod data, other types of data on spent fuel behavior in dry storage might support a higher limit. This isothermal temperature limit does not take credit for the decreasing rod temperature during dry storage. High-temperature tests based on creep rupture as the limiting mechanism indicate that storage at temperatures between 400 and 4400C may be feasible for rods that are annep>C may be feasible for rods that are annealed

  16. Effects of a carbon convection field on large diamond growth under high-pressure high-temperature conditions

    International Nuclear Information System (INIS)

    Large diamond crystals were successfully synthesized by a FeNi—C system using the temperature gradient method under high-pressure high-temperature conditions. The assembly of the growth cell was improved and the growth process of diamond was investigated. Effects of the symmetry of the carbon convection field around the growing diamond crystal were investigated systematically by adjusting the position of the seed crystal in the melted catalyst/solvent. The results indicate that the morphologies and metal inclusion distributions of the synthetic diamond crystals vary obviously in both symmetric and non-symmetric carbon convection fields with temperature. Moreover, the finite element method was applied to analyze the carbon convection mode of the melted catalyst/solvent around the diamond crystal. This work is helpful for understanding the growth mechanism of diamond

  17. Experimental determination of stability conditions of methane hydrate in aqueous calcium chloride solutions using high pressure differential scanning calorimetry

    International Nuclear Information System (INIS)

    The validity of differential scanning calorimetry (d.s.c.) as an alternate method of determination of thermodynamic conditions of stability of gas hydrates in aqueous media was asserted by comparison to literature data, in the case of methane hydrate in pure water and in sodium chloride solutions. Requirements for thermodynamic validity of the equilibrium temperatures measured by this technique were investigated and are discussed in details. New equilibrium data of (methane hydrate + water + methane) in aqueous calcium chloride solutions, in the concentration range from x=8.47·10-3 to x=53.27·10-3, were determined using the same method, in the pressure range 5 MPa to 11 MPa. Experimental results were compared to data computed using a model that is presented, showing very good agreement over a wide range of salt concentration. These results confirm the interesting perspectives of application of this technique in the field of gas hydrate thermodynamics

  18. Theoretical evaluation of radon emanation under a variety of conditions

    International Nuclear Information System (INIS)

    A cylindrical coordinate mathematical model to calculate 222Rn flux and movement was developed considering 222Rn production, decay, and diffusion in a multilayered, porous, permeable matrix. Air movement, transporting radon through the media, satisfies Darcy's law and is influenced by the air (barometric) pressure applied at the surface. Two zones of porous material have been defined, one with a 222Rn production term (the uranium ore zone) and the other without this term to simulate shotcrete or concrete ground support. A provision is made to evaluate the effect of a pinhole in an otherwise impermeable sealant. Comparisons are made between field measurements and predicted values. Specific examples are given of 222Rn flux from a finite ore-body model versus steady and periodic changes in barometric pressure. Also examined are 222Rn losses through pinholes for cases of linearly varying and static barometric pressures. The results suggest factors to consider in uranium mine radon control. For example, pinholes are not a serious problem since it appears that several thousand, 2 mm diameter pinholes per square meter are required to cause a significant loss of a barrier coating's effectiveness. (author)

  19. Shape-controlled synthesis of diamond crystal by epitaxial growth under high pressure and high temperature conditions

    International Nuclear Information System (INIS)

    In this paper, the diamond epitaxial growth mechanism has been studied in detail by employing several types of diamond as a seed in a catalyst—graphite system under high pressure and high temperature (HPHT) conditions. We find that the diamond nucleation, growth rate, crystal orientation, and morphology are significantly influenced by the original seeds. The smooth surfaces of seeds are beneficial for the fabrication of high-quality diamond. Our results reveal that the diamond morphology is mainly determined by the original shape of seeds in the early growth stage, but it has an adjustment process during the growth and leads to well symmetry. Additionally, we have also established the growth model for the twinned diamond grown on several seeds, and proposed the possible growth processes by tracking the particular shapes of seeds before and after treatment under HPHT conditions. These results suggest that the shape-controlled synthesis of diamond with well morphology can be realized by employing certain suitable diamond seeds. This work is expected to play an important role in the preparation of trustworthy diamond-based electronic and photonic devices. (interdisciplinary physics and related areas of science and technology)

  20. Environmentally-Assisted Cracking of Low-Alloy Reactor Pressure Vessel Steels under Boiling Water Reactor Conditions

    International Nuclear Information System (INIS)

    The present report summarizes the experimental work performed by PSI on the environmentally-assisted cracking (EAC) of low-alloy steels (LAS) in the frame of the RIKORR-project during the period from January 2000 to August 2001. Within this project, the EAC crack growth behaviour of different low-alloy reactor pressure vessel (RPV) steels, weld filler and weld heat-affected zone materials is investigated under simulated transient and steady-state BWR/NWC power operation conditions. The EAC crack growth behaviour of different low-alloy RPV steels was characterized by slow rising load (SRL) / low-frequency corrosion fatigue (LFCF) and constant load tests with pre-cracked fracture mechanics specimens in oxygenated high-temperature water at temperatures of either 288, 250, 200 or 150 C. These tests revealed the following important interim results: Under low-flow and highly oxidizing (ECP >= 100 mV SHE) conditions, the ASME XI 'wet' reference fatigue crack growth curve could be significantly exceeded by cyclic fatigue loading at low frequencies (<0.001 Hz), at high and low load-ratios R, and by ripple loading near to DKth fatigue thresholds. The BWR VIP 60 SCC disposition lines may be significantly or slightly exceeded (even in steels with a low sulphur content) in the case of small load fluctuations at high load ratios (ripple loading) or at intermediate temperatures (200 -250 C) in RPV materials, which show a distinct susceptibility to dynamic strain ageing (DSA). (author)

  1. Study of hydride blisters grown on Zr-2.5Nb pressure tube spool piece under simulated condition of in-reactor pressure and temperature

    International Nuclear Information System (INIS)

    Indian Pressurised Heavy Water Reactor (PHWR) have pressure tubes, made from zirconium alloy. These pressure tubes undergo corrosion with the high temperature (300 deg C) heavy water coolant under the reactor environment and pick up a part of hydrogen generated as result of this corrosion reaction. This hydrogen affects the integrity of pressure tubes in many ways; nucleation and growth of hydride blisters being one of them. The present study has been carried out to understand the mechanisms of nucleation and growth of hydride blisters and their effect on the serviceability of the component in the reactor environment. (author)

  2. Assessment of effect of operating conditions of nuclear power facilities on Service life of pressurizer vessel in WWER-440 type nuclear power plant

    International Nuclear Information System (INIS)

    A calculation analysis is presented of the effect of operating conditions of nuclear power facilities on the pressure vessel of the pressurizer in the primary circuit of a WWER-440 reactor using programs for strength calculations by the finite element method. The boundary conditions of the calculation are given as is an example of the calculation of stress in selected sections on the bottom and neck of the pressurizer during the transient which arises by the shutdown of one turbine with a quick-acting valve during rated power of the unit. The calculated value of the coefficient of damage cumulation for one pressure test is 4.5x10-5, for one start-up and shutdown it is 7.5633x10-4 and for one transient change 4x10-6. Graphically presented are actual values of force and temperature stresses. (J.B.) 5 figs., 15 refs

  3. Are processing conditions similar in ball milling and high-pressure torsion? The case of the tetragonal-to-monoclinic phase transition in ZrO2 powders

    International Nuclear Information System (INIS)

    Y2O3 partially stabilized zirconium oxide powders have been mechanically processed by ball milling. A tetragonal-to-monoclinic phase transition occurred, accompanied by a refinement of the microstructure, and an increase in the dislocation density. The final phase composition, average size of coherent diffraction domains and dislocation density are comparable to those obtained after high-pressure torsion. This suggests that powder particles experience similar mechanical deformation conditions when involved in a collision or submitted to high-pressure torsion.

  4. Atomistic simulations of the hcp-to-fcc transition in nanometer-sized Co domains embedded in a Cu matrix under different pressure and stress conditions

    Science.gov (United States)

    Delogu, Francesco

    2007-10-01

    Molecular dynamics simulations have been employed to investigate the thermodynamic behavior of Co domains with characteristic size of about 3nm embedded in a crystalline Cu matrix. Co domains are seen to undergo a hcp-to-fcc transition at temperatures dependent on the relative orientation between the Co and Cu crystalline lattices, as well as on the pressure and stress conditions applied to the matrix. No orientation effect is observed at null external pressure and stress. The transition temperature increases instead with the pressure according to a univocal trend, whereas the effect of uniaxial stress depends on the relative orientation of the Co and Cu lattices.

  5. Crack growth behaviour of low alloy steels for pressure boundary components under transient light water reactor operating conditions (CASTOC)

    Energy Technology Data Exchange (ETDEWEB)

    Foehl, J.; Weissenberg, T. [Materialpruefungsanstalt, Univ. Stuttgart (Germany); Gomez-Briceno, D.; Lapena, J. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT) (Spain); Ernestova, M.; Zamboch, M. [Nuclear Research Inst. (NRI) (Czech Republic); Seifert, H.P.; Ritter, S. [Paul Scherrer Inst. (PSI) (Switzerland); Roth, A.; Devrient, B. [Framatome ANP GmbH (F ANP) (Germany); Ehrnsten, U. [Technical Research Centre of Finland (VTT) (Finland)

    2004-07-01

    The CASTOC project addresses environmentally assisted cracking (EAC) phenomena in low alloy steels used for pressure boundary components in both Western type boiling water reactors (BWR) and Russian type pressurised water reactors (VVER). It comprises the four work packages (WP): inter-laboratory comparison test (WP1); EAC behaviour under static load (WP2), EAC behaviour under cyclic load and load transients (WP3); evaluation of the results with regard to their relevance for components in practice (WP4). The use of sophisticated test facilities and measurement techniques for the on-line detection of crack advances have provided a more detailed understanding of the mechanisms of environmentally assisted cracking and provided quantitative data of crack growth rates as a function of loading events and time, respectively. The effect of several major parameters controlling EAC was investigated with particular emphasis on the transferability of the results to components in service. The obtained crack growth rate data were reflected on literature data and on commonly applied prediction curves as presented in the appropriate Code. At relevant stress intensity factors it could be shown that immediate cessation of growing cracks occurs after changing from cyclic to static load in high purity oxygenated BWR water and oxygen-free VVER water corresponding to steady state operation conditions. Susceptibility to environmentally assisted cracking under static load was observed for a heat affected zone material in oxygenated high purity water and also in base materials during a chloride transient representing BWR water condition below Action Level 1 of the EPRI Water Chemistry Guidelines according to the lectrical conductivity of the water but in the range of Action Level 2 according to the content of chlorides. Time based crack growth was also observed in one Russian type base material in oxygenated VVER water and in one Western type base material in oxygenated high purity BWR water at stress intensity factors above the limit for linear elastic fracture mechanics. There is evidence that the prediction curves of the ASME Boiler and Pressure Vessel Code Section XI, Appendix A are not conservative for some relevant cases with regard to crack growth rates under cyclic load even in oxygenated high purity BWR water. The CASTOC results have provided an important contribution to the understanding of crack growth behavior on the one hand as a function of time and on the other hand as a consequence of the number and height of loading events. This is an important key for the evaluation of transient events, which may occur in a plant during service. (orig.)

  6. Crack growth behaviour of low alloy steels for pressure boundary components under transient light water reactor operating conditions (CASTOC)

    International Nuclear Information System (INIS)

    The CASTOC project addresses environmentally assisted cracking (EAC) phenomena in low alloy steels used for pressure boundary components in both Western type boiling water reactors (BWR) and Russian type pressurised water reactors (VVER). It comprises the four work packages (WP): inter-laboratory comparison test (WP1); EAC behaviour under static load (WP2), EAC behaviour under cyclic load and load transients (WP3); evaluation of the results with regard to their relevance for components in practice (WP4). The use of sophisticated test facilities and measurement techniques for the on-line detection of crack advances have provided a more detailed understanding of the mechanisms of environmentally assisted cracking and provided quantitative data of crack growth rates as a function of loading events and time, respectively. The effect of several major parameters controlling EAC was investigated with particular emphasis on the transferability of the results to components in service. The obtained crack growth rate data were reflected on literature data and on commonly applied prediction curves as presented in the appropriate Code. At relevant stress intensity factors it could be shown that immediate cessation of growing cracks occurs after changing from cyclic to static load in high purity oxygenated BWR water and oxygen-free VVER water corresponding to steady state operation conditions. Susceptibility to environmentally assisted cracking under static load was observed for a heat affected zone material in oxygenated high purity water and also in base materials during a chloride transient representing BWR water condition below Action Level 1 of the EPRI Water Chemistry Guidelines according to the lectrical conductivity of the water but in the range of Action Level 2 according to the content of chlorides. Time based crack growth was also observed in one Russian type base material in oxygenated VVER water and in one Western type base material in oxygenated high purity BWR water at stress intensity factors above the limit for linear elastic fracture mechanics. There is evidence that the prediction curves of the ASME Boiler and Pressure Vessel Code Section XI, Appendix A are not conservative for some relevant cases with regard to crack growth rates under cyclic load even in oxygenated high purity BWR water. The CASTOC results have provided an important contribution to the understanding of crack growth behavior on the one hand as a function of time and on the other hand as a consequence of the number and height of loading events. This is an important key for the evaluation of transient events, which may occur in a plant during service. (orig.)

  7. Valve inlet fluid conditions for pressurizer safety and relief valves for B and W 177-FA and 205-FA plants. Final report

    International Nuclear Information System (INIS)

    The overpressurization transients for the Babcock and Wilcox Company's 177- and 205-FA units are reviewed to determine the range of fluid conditions expected at the inlet of pressurizer safety and relief valves. The final Safety Analysis Report, extended high-pressure injection, and cold overpressurization events are considered. The results of this review, presented in the form of tables and graphs, provide input to the PWR utilities in their justification that the fluid conditions under which their valve designs were tested as part of the EPRI PWR Safety and Relief Valve Test Program are representative of those expected in their unit(s)

  8. BODILY CHANGES AND DEVELOPMENT OF PULMONARY RESISTANCE IN RATS LIVING UNDER COMPRESSED AIR CONDITIONS.

    Science.gov (United States)

    Smith, F J; Heim, J W; Thomson, R M; Drinker, C K

    1932-06-30

    1. 244 albino rats from standard Wistar Institute stock have been kept for periods up to 72 days under the following conditions. (a) Barometric pressure: 3040 mm. Hg. This means a partial pressure of oxygen of 635 mm. Hg and is equivalent to an 83.6 per cent oxygen mixture at normal barometric pressure. (b) Temperature: 28 degrees C. (c) Humidity: 50 per cent relative. (d) Rate of ventilation: 2660 liters per minute for all animals. (e) Food and daily care were provided which induced normal growth in rats in the usual laboratory quarters. 2. The harmful factor in this environment was the increased oxygen tension. In our experiments the acute effects were active hyperemia and edema of the lungs, just as have been described by many investigators. 3. Only a small percentage of rats die from acute oxygen poisoning at the pressure employed. The majority return to good health objectively and survive several months of exposure. 4. Rats under 1 month of age display no clinical signs of acute oxygen poisoning, while in older animals the severity of the reaction and the mortality is directly proportional to the advance in age. 5. The symptoms of acute oxygen poisoning appear on the 3rd day of exposure in adults and reach maximum intensity during the 4th day, all deaths occurring at this time. 6. A continued weight loss is found in old rats, while the young gain weight, but not with normal vigor. 7. Adaptation to this toxic oxygen tension occurs in the albino rat during the first exposure, so that on reexposure acute oxygen poisoning does not develop. 8. Respiratory infection occurred sporadically in roughly 20 per cent of the normal adult rats in our laboratory colony. About the same incidence was found in the experimental rats during exposure; in most of these, chronic bronchiectasis and bronchopneumonia followed and proved fatal, indicating a lowered resistance in exposed animals. 9. Most rats exposed to an 80 per cent oxygen tension late in pregnancy have premature litters and die of acute oxygen poisoning, but if exposed early in pregnancy the majority survive. 10. Litters born during the first exposure of the mother are approximately 50 per cent underweight and die during the first 24 hours after birth. 11. A female, rendered resistant by a first exposure, produced a healthy litter during second exposure. 12. The continuous failure of adults to gain in weight and the fact that young animals grow slowly, together with the slowly progressing pulmonary pathology (11), indicate that high oxygen tensions not only produce acute changes in the lungs but also some alteration in the normal physiological processes, which may be termed "chronic oxygen poisoning." PMID:19870055

  9. Evaluation of Low Pressure Fogging System for Improving Crop Yield of Tomato (Lycopersicon esculentum Mill.: Grown under Heat Stress Conditions

    Directory of Open Access Journals (Sweden)

    Kobi Shilo

    2013-06-01

    Full Text Available In Mediterranean regions, many tomato plants are grown throughout the hot summer period (May–September in sheltered cultivation, mainly for plant protection reasons. Most of the shelters that are used are low cost net houses covered with 50 mesh insect proof net. In most cases these net houses have a flat roof and no ventilation or climate control measures. This insufficient ventilation during the hot summer leads to above optimal air temperatures and causes moderate heat stress inside the shelters, which leads to yield reduction. The aim of this study was to evaluate the ability of a simple and inexpensive low pressure fogging system installed in a naturally ventilated net house to lower temperatures and improve the yield during the summer. The study showed that in areas where relative air humidity (RH during the daytime is less than 60%, tomato plants improved their performance when grown through the summer in net houses under moderate heat stress. Under fogging conditions pollen grain viability and fruit set were significantly improved. This improvement influenced the yield picked during September (104–136 DAP. However, total seasonal yield was not affected by the fogging treatment.

  10. Instability of the two-layered thick-walled esophageal model under the external pressure and circular outer boundary condition.

    Science.gov (United States)

    Yang, W; Fung, T C; Chian, K S; Chong, C K

    2007-01-01

    The mucosal folding is a phenomenon observed for some biological tissues, including the pulmonary airway and gastrointestinal tract. In order to understand the mechanism of the formation of mucosal folding, a thick-walled two-layered cylindrical mathematical model was developed to investigate the buckling behavior under the external pressure and circular outer boundary condition. With the finite element method, the validity and accuracy of the proposed model was verified. The results showed that the fold number was in the range of 4-6, which was agreed with the experimental observation for the mucosal folding of a porcine esophagus. The fold number was found to decrease with the increase in the ratio of the inner to outer material stiffness. The increase in the thickness of inner layer also caused a slight declination of the fold number. Since the effects of both the material and geometrical nonlinearities have been accounted for, this model is more general to be used for the prediction of the buckling behavior of the layered structure with a wide range of thickness ratios and/or stiffness ratios. PMID:16677658

  11. Spatial-Temporal Patterns in a Dielectric Barrier Discharge under Narrow Boundary Conditions in Argon at Atmospheric Pressure

    International Nuclear Information System (INIS)

    Pattern formation phenomena are investigated in a dielectric barrier discharge under narrow boundary conditions in argon at atmospheric pressure. The discharge shows various scenarios with the increasing applied voltage. This is the first observation of alternating single spot and pair spots pattern and of a moving striation pattern in a dielectric barrier discharge system. The spatial-temporal correlations between discharge filaments in these patterns are measured by an optical method. The results show that the zigzag pattern is an interleaving of two sub-structure patterns, which ignites once for each sub-pattern per half cycle of the applied voltage. There is a temporal sequence inversion in consecutive half-cycles for the two sub-patterns. The pattern of alternating single spot and pair spots is also an interleaving of two sub-structure patterns. However, the pair spots sub-pattern ignites twice and the single spot sub-pattern ignites once per half cycle of the applied voltage. (physics of gases, plasmas, and electric discharges)

  12. Black Tea Lowers Blood Pressure and Wave Reflections in Fasted and Postprandial Conditions in Hypertensive Patients: A Randomised Study

    Directory of Open Access Journals (Sweden)

    Davide Grassi

    2015-02-01

    Full Text Available Hypertension and arterial stiffening are independent predictors of cardiovascular mortality. Flavonoids may exert some vascular protection. We investigated the effects of black tea on blood pressure (BP and wave reflections before and after fat load in hypertensives. According to a randomized, double-blind, controlled, cross-over design, 19 patients were assigned to consume black tea (129 mg flavonoids or placebo twice a day for eight days (13 day wash-out period. Digital volume pulse and BP were measured before and 1, 2, 3 and 4 h after tea consumption. Measurements were performed in a fasted state and after a fat load. Compared to placebo, reflection index and stiffness index decreased after tea consumption (p < 0.0001. Fat challenge increased wave reflection, which was counteracted by tea consumption (p < 0.0001. Black tea decreased systolic and diastolic BP (?3.2 mmHg, p < 0.005 and ?2.6 mmHg, p < 0.0001; respectively and prevented BP increase after a fat load (p < 0.0001. Black tea consumption lowers wave reflections and BP in the fasting state, and during the challenging haemodynamic conditions after a fat load in hypertensives. Considering lipemia-induced impairment of arterial function may occur frequently during the day, our findings suggest regular consumption of black tea may be relevant for cardiovascular protection.

  13. The accuracy of the crystal chemical parameters at high-pressure conditions from single-crystal X-ray diffraction in diamond-anvil cell

    DEFF Research Database (Denmark)

    Periotto, Benedetta

    2012-01-01

    The high-pressure studies have been increasingly applied for the investigation of crystal structures under non ambient-conditions and phase-transition of minerals forming the Earth’s lower crust and upper mantle. The knowledge of the behavior of minerals under non-ambient conditions has important applications also in the materials science as it can provide useful information about the properties and performance of new materials. Over the past decades, the research in this field has been strongly developed due to the advances in computer capabilities and to the technological improvements of X-ray instruments. At the same time, the high-pressure experiments have benefited by the strong improvements on the high-pressure devices, in particular the diamond-anvil cell (DAC). The aim of this research project is to assess the quality of the data obtained by means of the single-crystal X-ray diffraction technique through the study of different mineral phases. The procedure for setting up an experiment under high-pressure conditions, using a single crystal as sample held within a DAC, are presented here with all the details of the in situ measurements at high-pressure conditions. The research project started with a comparison between two different DACs, in order to define the capabilities of one of the most common types of pressure device, the ETH-type DAC. Application examples of data quality analysis have been conducted on pyroxenes (NaInSi2O6, orthoenstatite MgSiO3 and LiCrSi2O6), which are important components of the Earth’s lower crust and upper mantle. In the last part of the thesis, the berthierite sulfosalt (FeSb2S4) was measured under pressure in order to test the data accuracy on a slightly more complicated structure

  14. Role of Sediments and Nutrients in the Condition of a Coral Reef Under Tourist Pressure: Akumal México.

    Science.gov (United States)

    Naranjo-Garcia, M. J.; Vadés Lozano, D. S.; Real-De-Leon, E.; Lopez-Aguiar, K.; Garza-Perez, J. R.

    2014-12-01

    Akumal, Mexico, was the first tourist resort in the Mexican Caribbean mainland, its highly developed coastal zone lies directly above the phreatic, and it is directly connected to the sub-littoral waters. Akumal is also known as a well-developed fringing coral reef, now in a critical condition. The main objective of this study was to explore the relationship between two of the main indicators of human pressure (nutrients and sedimentation, linked to coastal development and water run-offs) and the condition of the reef benthos, during a year. The sampling design used four transects perpendicular to shore, associated to different tourist and water run-off exposure, for a total of 12 stations distributed in three different reef zones (transition zone, shallow and deep spurs and grooves). Monthly samples were collected: water samples close to the reef lagoon drain channels and at bottom depth at each station, and sediment traps were recovered and replaced also at each station. Reef Benthos videotransects were recorded bi-monthly at each station to assess its condition. Macroalgae and filamentous algae dominate benthic cover (up to 50%), hard-coral cover ranges from 5-9%. Five coral-diseases were recorded, affecting 10.16% of the coral colonies: Caribbean Ciliate Infection, White Band, Purple Spots, White Spots and Yellow Band. The sedimentation rate -sr- ranged from 0.13 to 83.7 mg/cm2/day during the year; 86% of the samples had a sr ? 10 mg/cm2/day (reefs not stressed); 13% of the samples had a sr ranging from 10 to 50 mg/cm2/day (stressed reefs); and 1% of the samples were over the critical threshold (>50 mg/cm2/day). Dissolved Inorganic Nitrogen concentrations during the year were above those recorded previously in Caribbean reefs. The most abundant fraction was ammonium, surpassing both Mexican norms: For protection of aquatic life in coastal zones (0.01 mg/L), and the critical threshold for aquatic life (0.4 mg/L). These concentration limits are considered as drivers of eutrophication, one of the main established causes of reef degradation globally. High concentrations of ammonium and other nutrients have been linked to increases in algae cover and coral diseases incidence, and to decreases in rates of coral calcification, fertility, production and viability of coral larvae, and the associated diversity loss.

  15. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    Science.gov (United States)

    Fu, Qi; Socki, R. A.; Niles, P. B.

    2010-01-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the 13C values of CH4 and C2H6 were -50.3% and -39.3% (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a (sigma)C-13 value of -19.2%, which was 3.2% heavier than its source, formic acid. The (sigma)C-13 difference between CO2 and CH4 was 31.1%, which was higher than the value of 9.4% calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1%) observed in similar experiments previously performed at 400 C and 50 MPa with longer reaction times. CH4 is 11.0% less enriched in C-13 than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which confirms the hypothesis regarding the reaction pathways of hydrothermal abiotic organic synthesis proposed by Fu et al. (2007, 2008). In this proposed pathway, hydroxymethylene (-CHOH) groups serve as organic intermediaries on mineral surfaces while dissolved H2 serves as a chain terminator/breaker to generate short chain hydrocarbons and oxygenated compounds. This pathway is different from the carbide polymerization theory of Fischer- Tropsch-type (FTT) synthesis in a gas phase. The observed increase of (sigma)C-13 values of C1 and C2 alkanes with carbon number in our hydrothermal experiments can be readily interpreted by hydroxymethylene pathway, and might be used to differentiate between hydroxymethylene and carbide polymerization pathways. Carbon isotope analysis of alcohols on mineral catalyst surfaces is under way to provide further constraints on formation of organic compounds by FTT in hydrothermal systems.

  16. Frequency response of the pore pressure wells - from tidal to seismic frequency -

    Science.gov (United States)

    Yanagidani, T.; Kano, Y.; Yamashita, F.

    2002-12-01

    Poroelastic theory states that when a porous aquifer is under complete undrained conditions, i.e. a porous medium is compressed or extended without allowing fluid to flow, the applied stress is always borne by pore fluid and skeletal framework of the rock. Thus the pore pressure must be a direct sensor of the crustal stress change. However, this has never been clearly observed, because the pore pressure of aquifer would often measure through the water level in an open well under the assumption that it is in equilibrium with the pore pressure. In open wells, changes in pore pressure must be accompanied with flow into or out of the wall, which definitely prevents the well from being a gage of pore pressure in an aquifer. Limited hydraulic communication between well and aquifer causes the delay and attenuation in frequency response. And the dimension and geometry of well also greatly affect the performance. We could overcome these shortcomings by stopping up a flowing well bore and directly measuring the fluid (pore) pressure, p within it, and we found that the fluid pressure of such closed wells show the first-order response from tidal to seismic frequencies. A site-investigation tunnel was excavated at 350 m depth from the gallery of the Kamioka mine across the Mozumi fault, a part of the Atotsugawa fault system in central Japan. We have monitored the fluid pressure using pressures gage (full scale is 2.069 MPa, resolution is 16 bit, and sampling rate is 20 Hz) at two well bores on both sides of the fault; C-well, the diameter is 140 mm, the length is 600 m, the inclination is -70°, and the flowing rate is 375 l/min; A-well, the diameter is 76 mm, the length is 15 m, the inclination is -5°, and the flowing rate is 25 l/min. We have also observed the barometric pressure, b in the tunnel. On stopping up a well bore, the pore pressure have gradually built up and attained the stable state in a half year (C-well; 1.43MPa, A-well; 0.99MPa). Tiny but clear fluctuations of pore pressure due to the earth tides were observed immediately after stopping up the well bore. Their amplitudes are CO1= 52 Pa, CM2=105 Pa, AO1=24 Pa, AM2=59 Pa at the equilibrium. There was no phase delay between two well-bores. The barometric efficiency, ? ( = ?p / ?b ) could be properly determined; 0.46 for C-well, and 0.37 for A-well. Two hydrograms of the April 26, 2002 Mariana earthquake (MW=7.1; the epicentral distance is 24.0°) were indistinguishable from each other, except for their amplitude(?pC/?pA=1.27). Besides the sameness of two waveforms, they are also significantly similar to the radial recording of STS-1 seismometer (velocity of ground motion) including shear and surface waves. These observations are confirmed that when the seismic (plane) waves are transmitted through the porous medium saturated with water, there is no relative movement between pore fluid and skeletal framework of the rock, and that the applied stress is always shared with fluid and skeletal framework of the rock at a constant ratio.

  17. Pressure ulcers

    OpenAIRE

    Grey, Joseph E.; Harding, Keith G.; Enoch, Stuart

    2008-01-01

    Unrelieved pressure or friction of the skin, particularly over bony prominences, can lead to pressure ulcers, which affect up to one third of people in hospitals or community care, and one fifth of nursing home residents. Pressure ulcers are more likely in people with reduced mobility and poor skin condition, such as older people or those with vascular disease.

  18. Speciation of High-Pressure Carbon-Saturated COH Fluids at Buffered fO2 Conditions: An Experimental Approach

    Science.gov (United States)

    Tumiati, S.; Tiraboschi, C.; Recchia, S.; Poli, S.

    2014-12-01

    The quantitative assessment of species in COH fluids is crucial in modelling mantle processes. For instance, H2O/CO2 ratio in the fluid phase influences the location of the solidus and of carbonation/decarbonation reactions in peridotitic systems . In the scientific literature, the speciation of COH fluids has been generally assumed on the basis of thermodynamic calculations using equations of state of simple H2O-non-polar gas systems (e.g., H2O-CO2-CH4). Only few authors dealt with the experimental determination of high-pressure COH fluid species at different conditions, using diverse experimental and analytical approaches (e.g., piston cylinder+capsule-piercing+gas-chromatography/mass-spectrometry; cold-seal+silica glass capsules+Raman). We performed experiments on COH fluids using a capsule-piercing device coupled with a quadrupole mass spectrometry. This type of analyzer ensures superior performances in terms of selectivity of molecules to be detected, high acquisition rates and extended linear response range. Experiments were carried out in a rocking piston cylinder apparatus at pressure of 1 GPa and temperatures from 800 to 900°C. Carbon-saturated fluids were generated through the addition of oxalic acid dihydrate and graphite. Single/double capsules and different packing materials (BN and MgO) were used to evaluate the divergence from the thermodynamic speciation model. Moreover, to assess the effect of solutes on COH fluid speciation we also performed a set of experiments adding synthetic forsterite to the charge. To determine the speciation we assembled a capsule-piercing device that allows to puncture the capsule in a gas-tight vessel at 80°C. The extraction Teflon vessel is composed of a base part, where the capsule is allocated on a steel support, and a top part where a steel drill is mounted. To release the quenched fluids from the capsule, the base part of vessel is hand-tighten to the top part, allowing the steel pointer to pierce the capsule. The evolved gases are then convoyed to a quadrupole mass spectrometer through a heated line to avoid the condensation of water. Our results suggest that fluid speciation can diverge considerably compared to the thermodynamic model depending on the experimental strategies adopted and on the presence of solutes in complex COH systems.

  19. Contrasting P-T conditions recorded in ultramafic high-pressure rocks from the Variscan Schwarzwald (F.R.G.)

    OpenAIRE

    Kalt, Angelika; Altherr, Rainer; Hanel, Michael

    2006-01-01

    This paper presents mineralogical and textural data as well as thermobarometric calculations on ultramafic high-pressure rocks from the Variscan basement of the Schwarzwald (F.R.G.). The rocks form small isolated bodies within low-pressure / high-temperature gneisses and migmatites. The results of this study constrain contrasting P-T evolutions for four garnet-bearing ultramafic high-pressure rocks. Two magnesian garnet-spinal peridotites sampled near the southern margin of the Central Schwar...

  20. RELAP5 Capability to Predict Pressure Wave Propagation Phenomena in Single- and Two-Phase Flow Conditions

    OpenAIRE

    Lukasz Sokolowski; Zbigniew Koszela

    2012-01-01

    Correct evaluation of the hydrodynamic loads induced by large and rapid pressure waves propagating with the speed of sound along the reactor piping systems and Reactor Pressure Vessel (RPV) is an important and difficult issue of nuclear power plant safety. The pressure shock transients and resulting hydrodynamic loads on the pipes and RPV structures are commonly calculated with one-dimensional thermo-hydraulic system codes such as RELAP5, TRACE, DRAKO and ROLAST. In Sweden, the most widely us...

  1. Measuring unsteady pressure on rotating compressor blades. [with semiconductor strain gages under gas turbine engine operating conditions

    Science.gov (United States)

    Englund, D. R.; Grant, H. P.; Lanati, G. A.

    1979-01-01

    The capability for accurate measurement of unsteady pressure on the surface of compressor and fan blades during engine operation was established. Tests were run on miniature semiconductor strain gage pressure transducers mounted in several arrangements. Both surface mountings and recessed flush mountings were tested. Test parameters included mounting arrangement, blade material, temperature, local strain in the blade, acceleration normal to the transducer diaphragm, centripetal acceleration, and pressure. Test results showed no failures of transducers or mountings and indicated an uncertainty of unsteady pressure measurement of approximately + or - 6%, plus 0.1 kPa for a typical application.

  2. Fuel pellets from biomass: The importance of the pelletizing pressure and its dependency on the processing conditions

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Holm, Jens K.

    2011-01-01

    The aim of the present study was to identify the key factors affecting the pelletizing pressure in biomass pelletization processes. The impact of raw material type, pellet length, temperature, moisture content and particle size on the pressure build up in the press channel of a pellet mill was studied using a single pellet press unit. It was shown that the pelletizing pressure increased exponentially with the pellet length. The rate of increase was dependent on biomass species, temperature, moisture content and particle size. A mathematical model, predicting the pelletizing pressure, was in good accordance with experimental data. It was shown that increasing the temperature resulted in a decrease of the pelletizing pressure. Infrared spectra taken from the pellets surface, indicated hydrophobic extractives on the pellet surface, for pellets produced at higher temperatures. The extractives act as lubricants, lowering the friction between the biomass and the press channel walls. The effect of moisture content on the pelletizing pressure was dependent on the raw material species. Different particle size fractions, from below 0.5 mm up to 2.8 mm diameter, were tested, and it was shown that the pelletizing pressure increased with decreasing particle size. The impact of pelletizing pressure on pellet density was determined, and it was shown that a pelletizing pressure above 200 MPa resulted only in minor increase in pellet density. 2011 Published by Elsevier Ltd.

  3. Effect of aviation fuel type and fuel injection conditions on the spray characteristics of pressure swirl and hybrid air blast fuel injectors

    Science.gov (United States)

    Feddema, Rick

    Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements. Fuel injector spray atomization performance is affected by the type of fuel injector, fuel liquid properties, fuel injection pressure, fuel injection temperature, and ambient pressure. Performance of pressure swirl atomizer and hybrid air blast nozzle type fuel injectors are compared in this study. Aviation jet fuels, JP-8, Jet A, JP-5, and JP-10 and their effect on fuel injector performance is investigated. Fuel injector set conditions involving fuel injector pressure, fuel temperature and ambient pressure are varied in order to compare each fuel type. One objective of this thesis is to contribute spray patternation measurements to the body of existing drop size data in the literature. Fuel droplet size tends to increase with decreasing fuel injection pressure, decreasing fuel injection temperature and increasing ambient injection pressure. The differences between fuel types at particular set conditions occur due to differences in liquid properties between fuels. Liquid viscosity and surface tension are identified to be fuel-specific properties that affect the drop size of the fuel. An open aspect of current research that this paper addresses is how much the type of aviation jet fuel affects spray atomization characteristics. Conventional aviation fuel specifications are becoming more important with new interest in alternative fuels. Optical patternation data and line of sight laser diffraction data show that there is significant difference between jet fuels. Particularly at low fuel injection pressures (0.345 MPa) and cold temperatures (-40 C), the patternation data shows that the total surface area in the spray at 38.1 mm from the pressure swirl injector for the JP-10 fuel type is one-sixth the amount of the JP-8. Finally, this study compares the atomizer performance of a pressure swirl nozzle to a hybrid air blast nozzle. The total surface area for both the hybrid air blast nozzle and the pressure swirl nozzle show a similar decline in atomization performance at low fuel injection pressures and cold temperatures. However, the optical patternator radial profile data and the line of sight laser diffraction data show that the droplet size and spray distribution data are less affected by injection conditions and fuel type in the hybrid air blast nozzle, than they are in the pressure swirl nozzle. One explanation is that the aerodynamic forces associated with the swirler on the hybrid air blast nozzle control the distribution droplets in the spray. This is in contrast to the pressure swirl nozzle droplet distribution that is controlled by internal geometry and droplet ballistics.

  4. Modeling of high pressure steam condensation in the presence of a noncondensable gas in a vertical tube with a secondary pool condition

    International Nuclear Information System (INIS)

    An improved theoretical model was developed to investigate the effects of noncondensable gas on the heat transfer coefficient of steam condensing inside a vertical tube using the heat and mass transfer analogy with a secondary pool condition. The model predicted well the experimental data of Oh and Rebankar (2006) and Kim (2000), which had been obtained from the in-tube steam condensation submerged in water pool with air. A parametric study was performed with the system pressure and condenser tube diameter as parameters. Results show that total and overall heat transfer coefficients decreased as the system pressure and the condenser tube diameter increased in low pressure, but they became saturated in high pressure. (authors)

  5. Potential application of a flash-type barometric desalination plant powered by waste heat from electric-power stations in Cyprus

    International Nuclear Information System (INIS)

    This paper describes and evaluates the results of a study into the problems of freshwater production and shortages on the island of Cyprus. The use of a novel barometric flash-type desalinator, driven by otherwise waste-heat from the island's power-stations, is proposed as a means of increasing freshwater supplies. Mathematical models are described and used to investigate the thermodynamic performance and economic viability of the proposed system. Although water and electricity supply data for the island of Cyprus were used for the purposes of this investigation, the overall findings are thought have a wider applicability

  6. Effects of storage conditions before or after high-hydrostatic pressure on inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in oysters

    Science.gov (United States)

    The effect of storage conditions on subsequent high-hydrostatic pressure (HHP) inactivation of V. parahaemolyticus and V. vulnificus in oyster meat was investigated. Live oysters were inoculated with V. parahaemolyticus or V. vulnificus to ca. 7-8 log MPN/g by feeding and stored at different conditi...

  7. Desaturation of a clay-stone around a ventilated gallery: numerical modelling of pressures and water contents under various conditions

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. We present simulation tests focusing on the drying process around a gallery in an initially saturated (water-filled) porous clay rock, in the framework of a research on the isolation properties and hydro-mechanical behaviour of a clayey geologic repository for radioactive waste. The saturated/unsaturated hydrodynamic parameters used in these tests correspond to a hypothetical clay-stone, similar to the 130 m thick Callovo-Oxfordian formation located between depths 400 m and 600 m at the Meuse / Haute-Marne (MHM) Underground Research Laboratory (URL), operated by ANDRA (Bure, France). The simulations tests were designed according to 3 'types' of computational geometries. The drying period was extended to very long time scales in some cases. The clay rock was taken homogeneous in many tests, but the damaged zone was represented in some (Type III) tests. Type (I) tests are conducted in a simplified non circular geometry. Assuming a square cross-section for the drift, the drying process is obtained by imposing a fixed suction on a flat piece of wall at the roof. The bottom of the porous domain coincides with the roof of the drift. The imposed suction at the roof affects the near field pressure both horizontally and vertically. Type (II) tests reproduce the circular cylindrical geometry of a partially or perfectly filled gallery, with drying conditions imposed at both ends of the drift. Finally, Type (III) tests consider trift. Finally, Type (III) tests consider the case of an empty ventilated cylindrical drift with circular cross-section. In this case the drying is imposed on the curved walls of the drift via a transmission mechanism thanks the 'macro-porous immersion' method. In all cases, the drying of the porous clay rock is modeled by imposing a suction condition (?), obtained from relative air humidity (HR) via Kelvin's law (?). Briefly, the macro-porous immersion method consists in the following interrelated procedures. First, the volumetric excavation (cylindrical drift) is discretized and internalized as a 3D 'macro-porous' body within the computational porous domain. Secondly, the properties of this internal macro-porous body are adjusted in such a way that it will transmit properly the imposed suction (or pressure, or flux, as the case may be) from external to internal boundaries. Here, the suction is imposed on the entry face of the gallery (external boundary), and it is transmitted to the clay/gallery interface (internal boundary). The macro-porous body has a porosity of 100%, a large Darcy permeability compared to the clay-stone, and other special nonlinear and non-isotropic unsaturated properties. Briefly, numerical modelling was conducted with BIGFLOW 3D, an implicit finite volume solver of the saturated/unsaturated Richards equation in mixed form (moisture content '?', pressure head 'h'). We used the nonlinear Van Genuchten / Mualem conductivity and water retention curves (K(h); ?(h)) in the unsaturated zone. A specific elastic storativity (SS) was added in the saturated zone to take into account slight deformation mechanisms in a simplified way (the storativity model does not deal with total stress; it assumes ??EFF ? ?p, where p is pore pressure, and ?EFF is Terzaghi's effective stress taken positive when extensional). Finally, the BIGFLOW code can also handle 3D heterogeneity and nonlinear diagonal anisotropy, that is: [Kii(h,x,y,z); ?(h,x,y,z)]. We used these additional capabilities of the code in some of the tests. Figs.1 and 2 show the evolution of desaturation for a 'Type I' test, i.e., with suction imposed on a flat horizontal piece of wall located at the roof of the drift. The drift 'radius' (half-side) is R=2 m. The case shown here is only 'moderately dry': the prescribed suction is ?=3000 m (?30 MPa), corresponding to HR=80.74% at TAIR=25 C and PATM=1 bar (according to Kelvin's law). The imposed desaturation of the porous medium at the drift wall is significant (more than 50% drop of the degree of saturation). The steady state is atta

  8. Modelling of crud growth mechanisms under local boiling conditions in pressurized water reactors fuel clads leading to important volumes activities

    International Nuclear Information System (INIS)

    The Pressurized Water Reactors (PWRs) primary circuit materials are subject to general corrosion leading to soluble metallic element (mainly Fe, Ni, Cr, Mn, Co) transfer and subsequent ion precipitation processes on the primary circuit surfaces. When deposited on fuel rods, these species are activated by neutron flux. Thus, crud erosion and dissolution processes induce to primary coolant activity. During a normal operating cycle in a EDF PWR, the volume activity in the coolant is relatively stable (usually about 10-20 MBq.m-3 in 58Co). In some cycles (depending on fuel management), significant increases in 58Co and 51Cr volume activities are observed (10 to 100 times the ordinary volume activities). These increases of volume activities are due to local sub-cooled nucleate boiling on the 'hot' parts of fuel assemblies. As presented in this thesis, boiling at the top of some fuel assemblies may lead to much higher amount of metallic elements than usual (some micrometers). Indeed, boiling that can locally occurs under PWR conditions concentrates species and to increase significantly the quantity of deposited and precipitated material. Erosion flux is higher in these regions due to thicker crud thickness, involving a greater mass transfer of activated isotopes to the primary coolant. The OSCAR calculation code, developed by the 'Laboratoire de Modelisation des interactions et Transferts en Reacteur' in CEA, with these new mass transfer models can now well estimate the amount of deposit and the volume activities in the primary coolant in case of boiling in accordance with french PWR measurements. (author)

  9. Thermal-mechanical modelling of the pressure tube following fuel element contact under LOCA conditions in a CANDU-PHWR

    International Nuclear Information System (INIS)

    This paper quantifies the thermal-mechanical effects of potential contact between the fuel element and the pressure tube (FE/PT contact) during a postulated large break LOCA transient in a CANDU reactor. At issue is the possibility of local failure of the pressure tube early in the LOCA transient. Calculations have been performed using the code MINI-SMARTT which was developed specifically for this analysis. It is shown that pressure tube local strain is most sensitive to the contact conductance, contact width, and transient time of FE/PT contact. The strain response of the pressure tube is derived over a broad range for the above parameters. A critical FE/PT contact conductance value is derived as a function of contact width and judged to be sufficiently high that pressure tube failure would be precluded

  10. Intrinsic Properties of AFe2As2 (A = Ba, Sr) Single Crystal under Highly Hydrostatic Pressure Conditions

    OpenAIRE

    Matsubayashi, Kazuyuki; Katayama, Naoyuki; Ohgushi, Kenya; Yamada, Atsushi; Munakata, Kouji; Matsumoto, Takehiko; Uwatoko, Yoshiya

    2009-01-01

    We measured the electrical resistivity and ac magnetic susceptibility of BaFe2As2 and SrFe2As2 single crystals under pressure using a cubic anvil apparatus. For BaFe2As2, the antiferromagnetic (AF) and structural transitions are suppressed with increasing pressure. Unexpectedly, these transitions persist up to 8 GPa, and no signature of a superconducting transition was observed in the pressure range investigated here. On the other hand, the AF and structural transitions of S...

  11. Experimental and theoretical investigation of the dynamic behaviour of a reactor pressure vessel and a primary steam pipe line under operating conditions

    International Nuclear Information System (INIS)

    A new remotely operated snapback excitation system was used for vibration tests at the pressure vessel and a primary steam pipe of a nuclear power plant under different operating conditions (temperature 20-2850C in steps, internal pressure 0-70 bar). The measured acceleration-, displacement- and strain time histories were compared with results of pre-calculations of the test load cases using a FE-model. Additionally, a modal analysis of the measured signals permitted a comparison of resonance frequencies, mode shapes and damping values of the system investigated with the modal parameters of the computation model. (orig.)

  12. Biogas barometer; barometre biogaz

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-11-15

    The biogas sector has never before aroused so much attention as it does today. Elected officers and investors' interest has been fired by the gradual introduction of regulatory restrictions on the treatment of organic waste and the renewable energy commitments recently made by the European Union Member States. The biogas sector is gradually deserting its core activities of waste cleanup and treatment and getting involved in energy production, with so much enthusiasm that in some countries its scope of action has extended to using energy crops. Across the European Union, the sector's progress is as clear as daylight, as in 2009, primary energy growth leapt by a further 4.3 per cent. (author)

  13. Surface Enhanced Raman Spectroscopy on Carbonate Fluids at High Pressures: A New Technique to Study Fluid Species Under Geologically Relevant Conditions

    Science.gov (United States)

    Chopelas, A.; Black, J. R.; Kavner, A.; Manning, C. E.

    2010-12-01

    The physical and chemical behavior of fluid/mineral interfaces at high pressures and temperatures help govern the generation of magmas, the evolution of the continental crust, and the storage and cycling of volatiles such as water and carbon in and through the Earth’s crust and mantle reservoirs. Little is known of the speciation of silica- and oxidized carbon- bearing fluids at relevant conditions of pressure, temperature and concentration. Currently, our high pressure P/high temperature T Raman spectroscopy studies in the hydrothermal DAC have yielded promising insights into P,T dependence of carbon/bicarbonate speciation. However, due to the low intensity of Raman scattering, results can only be obtained on fluids with carbon species concentrations that are unreasonably high compared with actual geological fluids. To help examine the chemistry of geological fluids at relevant concentrations and P-T conditions, we are developing a technique known as Surface Enhanced Raman Spectroscopy (SERS) in the hydrothermal diamond anvil cell. SERS is a resonant Raman phenomenon yielding potentially large enhancements in spectroscopic signal for Raman-active species adsorbed on nano-structured metals. Currently, this technique is widely used in the chemistry community, and has been mostly been devoted to studying organic materials, including proteins, aromatics, etc, and fluid-nanoparticle interactions. Enhancements in Raman signal of a few orders of magnitude are typical. Here, we show our SERS results on dilute carbonate/bicarbonate solutions at ambient conditions, and at high pressures in the diamond anvil cell. We obtained ambient pressure SERS signal for a dilute 0.02 M bicarbonate/carbonate fluid, using Au, Ag, and Cu as nanoparticle substrates. In the diamond cell, we obtained SERS spectra on a ~0.1 M bicarbonate solution at pressures ranging from 1 GPa to 3 GPa. The SERS spectra revealed the same sequence carbonate/bicarbonate transformations we observed at higher concentrations with standard Raman techniques but with at least an order of magnitude enhancement. Our experiments suggest that SERS in conjunction with the hydrothermal diamond anvil cell is a promising technique to study not only oxidized carbon but also a variety of species such as sulfates, nitrates, or silicates in aqueous solutions at Earth-relevant conditions. In addition, it has promise as a method to examine species adsorbed specifically on mineral surfaces, and to ascertain the influence of pressure and temperature on the chemical behavior of species at fluid/mineral interfaces.

  14. RELAP5 Capability to Predict Pressure Wave Propagation Phenomena in Single- and Two-Phase Flow Conditions

    Directory of Open Access Journals (Sweden)

    Lukasz Sokolowski

    2012-01-01

    Full Text Available Correct evaluation of the hydrodynamic loads induced by large and rapid pressure waves propagating with the speed of sound along the reactor piping systems and Reactor Pressure Vessel (RPV is an important and difficult issue of nuclear power plant safety. The pressure shock transients and resulting hydrodynamic loads on the pipes and RPV structures are commonly calculated with one-dimensional thermo-hydraulic system codes such as RELAP5, TRACE, DRAKO and ROLAST. In Sweden, the most widely used computer code for this purpose is RELAP5. This code needs, therefore, to be assessed for its capability to predict pressure wave behavior. The conducted assessment involves simulations of single- and two-phase shock-tube problems and two-phase blowdown as well as water hammer experiments. The performed numerical experiments clearly show that RELAP5, with the proper time step and spatial mesh size, is capable of predicting the complex dynamics of single- and two-phase pressure wave phenomena with good to reasonable accuracy.

  15. Self-overcoming of the boiling condition by pressure increment in a water target irradiated by proton beam

    International Nuclear Information System (INIS)

    An experiment was conducted to examine and visualize the boiling phenomena inside a water target by irradiating it with a proton beam from MC-50 cyclotron. The boiling phenomena were recorded with a CMOS camera. While an increase of the fraction of the water vapor volume is generally considered to be normal when water is boiled by a proton beam, our experiment showed the opposite result. The volume expansion of the liquid water exceeded the compressibility of the initial air volume. A grid structure in front of the entrance window foil held the target volume constant. Therefore, the phenomena inside the target underwent an isochoric process, and the pressure inside the target was increased rapidly beyond the pressure at the boiling point. Consequently, there was no more bulk boiling in the Bragg-peak region in the target water. Our results show that the boiling of the water can be controlled by controlling the equilibrium pressure of the water target

  16. Self-overcoming of the boiling condition by pressure increment in a water target irradiated by proton beam

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Bong Hwan, E-mail: burnn@kirams.re.kr [Korea Institute of Radiological and Medical Sciences (KIRMAS), 75 Nowon-Gil, Nowon-Gu, Seoul 139-706 (Korea, Republic of); Kang, Joonsun; Jung, In Su; Ram, Han Ga; Park, Yeun Soo [Korea Institute of Radiological and Medical Sciences (KIRMAS), 75 Nowon-Gil, Nowon-Gu, Seoul 139-706 (Korea, Republic of); Cho, Hyung Hee [Department of Mechanical Engineering, Yonsei University, 134 Sinchon-Dong, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

    2013-11-11

    An experiment was conducted to examine and visualize the boiling phenomena inside a water target by irradiating it with a proton beam from MC-50 cyclotron. The boiling phenomena were recorded with a CMOS camera. While an increase of the fraction of the water vapor volume is generally considered to be normal when water is boiled by a proton beam, our experiment showed the opposite result. The volume expansion of the liquid water exceeded the compressibility of the initial air volume. A grid structure in front of the entrance window foil held the target volume constant. Therefore, the phenomena inside the target underwent an isochoric process, and the pressure inside the target was increased rapidly beyond the pressure at the boiling point. Consequently, there was no more bulk boiling in the Bragg-peak region in the target water. Our results show that the boiling of the water can be controlled by controlling the equilibrium pressure of the water target.

  17. Development of a CATHENA Fuel Channel Analysis Model for a Fuel Channel with Axial Variation of Radial Pressure Tube Creep in a Stratified Two-Phase Flow Condition

    International Nuclear Information System (INIS)

    A two-phase heat transfer phenomena in the fuel bundle strings located in a horizontal pressure tube with an axial variation of the radial creep, especially under a low stratified two-phase flow condition such as encountered in the CANDU reactor under the later stage of the blowdown phase of a LBLOCA, involves a complex heat transfer nature. This includes the conduction in the fuel rods, pressure tube, convection in the vapor and liquid regions, and radiation between the fuel rods exposed in the steam and the pressure tube, pressure tube and calandria tube. As these three modes of heat transfer has to be treated in a combined way, modeling the heat transfer phenomena inside the fuel bundle under the stratified flow during the later stage of LBLOCA blowdown has been one of the most challenging tasks in the CANDU safety analyses. The main reason for this hot attention is that it closely related to the integrity of the pressure tube. In this study a heat transfer model for handling this situation is developed, implemented and under preliminary testing of the analysis results. The analysis result up to now is encouraging and the validation of the model developed is ongoing. The major motivation of this study is to evaluate the conservatism of the current CANDU safety analysis methodology for a fuel channel with an axial variation of the radial creep of the pressure tube as easily experienced in the aged CANDU plant as it assumes the centerline of the fuel bundle string ishe centerline of the fuel bundle string is the same as that of the pressure tube

  18. Pulsed laser ablation plasmas generated in CO2 under high-pressure conditions up to supercritical fluid

    Science.gov (United States)

    Kato, Toru; Stauss, Sven; Kato, Satoshi; Urabe, Keiichiro; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo

    2012-11-01

    Pulsed laser ablation of solids in supercritical media has a large potential for nanomaterials fabrication. We investigated plasmas generated by pulsed laser ablation of Ni targets in CO2 at pressures ranging from 0.1 to 16 MPa at 304.5 K. Plasma species were characterized by optical emission spectroscopy, and the evolution of cavitation bubbles and shockwaves were observed by time-resolved shadowgraph imaging. Ni and O atomic emissions decreased with increasing gas pressure; however, near the critical point the intensities reached local maxima, probably due to the enhancement of the plasma excitation and effective quenching resulting from the large density fluctuation.

  19. Operational measures. Influence of the operational conditions of EDF's PWR reactors on the flux the pressure vessels receive

    International Nuclear Information System (INIS)

    The developments in fuel management for the REP-900 park have led to no substantial increase of the flux density on the pressure vessel. From the end of 1992, taking the safety parameters into account, loading diagrams with reduced flux density for UO2 fuel have been used. These are also meant to be utilised for MOX fuel. In the REP 1130, the lengthening of the cycle time with simultaneous lowering of the flux density seems possible. The flux density effect on the pressure vessel and on the radiation samples is constantly being followed. 2 figs., 1 tab

  20. Effects of injection conditions and Mach number on unsteadiness arising within coolant jets over a pressure side vane surface

    OpenAIRE

    BARIGOZZI, GIOVANNA; RAVELLI, SILVIA; ARMELLINI, ALESSANDRO; MUCIGNAT, CLAUDIO; CASARSA, LUCA

    2013-01-01

    The thermal performance of a gas turbine airfoil with a cooled pressure side and a trailing edge cutback is investigated and discussed in relationship with the unsteady behavior of coolant injection. The focus is on the pressure side coolant injection through discrete holes. The cascade was tested at an exit Mach number of 0.2 and 0.6 for different coolant to mainstream mass flow ratios. Laser Doppler Velocimetry (LDV) and high speed flow visualizations were used to investigate the unsteady m...

  1. Investigation of the axial dependence of coolant temperature noise at one-phase and two-phase flow conditions in a pressurized water reactor

    International Nuclear Information System (INIS)

    Results of the investigation of coolant temperature noise in a pressurized water reactor are presented. The experiments were performed using a specially aquipped fuel assembly in the WWER-70 reactor of the Rheinsberg nuclear power plant. The interpretation of the measuring values is based on a thermohydraulic model which describes the axial dependence of the temperature noise at one-phase and two-phase flow conditions. (author)

  2. Research on the influence of the technical conditions of a homogenizer pump on the quality of the process of pressure homgenization

    OpenAIRE

    Popko H.; Komsta H.; Popko R.; Hys L.

    2002-01-01

    The research presented in this paper refers to the role of the technical condition of the plunger pump’s working units vis-a-vis the quality of homogenized emulsion. Technical condi- tion was determined ‘on line’ by analysing the measured value of the signal of homogenization pressure. This signal contains - among other things - some information about the condition of the plunger pump’s valve unit. The process quality was determined by the p...

  3. Temperature-pressure conditions in coalbed methane reservoirs of the Black Warrior basin: Implications for carbon sequestration and enhanced coalbed methane recovery

    Science.gov (United States)

    Pashin, J.C.; McIntyre, M.R.

    2003-01-01

    Sorption of gas onto coal is sensitive to pressure and temperature, and carbon dioxide can be a potentially volatile supercritical fluid in coalbed methane reservoirs. More than 5000 wells have been drilled in the coalbed methane fields of the Black Warrior basin in west-central Alabama, and the hydrologic and geothermic information from geophysical well logs provides a robust database that can be used to assess the potential for carbon sequestration in coal-bearing strata.Reservoir temperature within the coalbed methane target zone generally ranges from 80 to 125 ??F (27-52 ??C), and geothermal gradient ranges from 6.0 to 19.9 ??F/1000 ft (10.9-36.2 ??C/km). Geothermal gradient data have a strong central tendency about a mean of 9.0 ??F/1000 ft (16.4 ??C/km). Hydrostatic pressure gradients in the coalbed methane fields range from normal (0.43 psi/ft) to extremely underpressured (carbon dioxide. However, reservoirs have potential for supercritical fluid conditions beyond a depth of 2480 ft (756 m) under normally pressured conditions. All target coal beds are subcritically pressured in the northeastern half of the coalbed methane exploration fairway, whereas those same beds were in the supercritical phase window prior to gas production in the southwestern half of the fairway. Although mature reservoirs are dewatered and thus are in the carbon dioxide gas window, supercritical conditions may develop as reservoirs equilibrate toward a normal hydrostatic pressure gradient after abandonment. Coal can hold large quantities of carbon dioxide under supercritical conditions, and supercritical isotherms indicate non-Langmiur conditions under which some carbon dioxide may remain mobile in coal or may react with formation fluids or minerals. Hence, carbon sequestration and enhanced coalbed methane recovery show great promise in subcritical reservoirs, and additional research is required to assess the behavior of carbon dioxide in coal under supercritical conditions where additional sequestration capacity may exist. ?? 2003 Elsevier Science B.V. All rights reserved.

  4. Analysis of the critical heat flux in round vertical tubes under low pressure and flow oscillation conditions. Applications of artificial neural network

    International Nuclear Information System (INIS)

    Artificial neural networks (ANNs) for predicting critical heat flux (CHF) under low pressure and oscillation conditions have been trained successfully for either natural circulation or forced circulation (FC) in the present study. The input parameters of the ANN are pressure, mean mass flow rate, relative amplitude, inlet subcooling, oscillation period and the ratio of the heated length to the diameter of the tube, L/D. The output is a nondimensionalized factor F, which expresses the relative CHF under oscillation conditions. Based on the trained ANN, the influences of principal parameters on F for FC were analyzed. The parametric trends of the CHF under oscillation obtained by the trained ANN are as follows: the effects of pressure below 500 kPa are complex due to the influence of other parameters. F will increase with increasing mean mass flow rate under any conditions, and will decrease generally with an increase in relative amplitude. F will decrease initially and then increase with increasing inlet subcooling. The influence curves of mean mass flow rate on F will be almost the same when the period is shorter than 5.0 s or longer than 15 s. The influence of L/D will be negligible if L/D>200. It is found that the minimum number of neurons in the hidden layer is a product of the number of neurons in the input layer and in the output layer

  5. The Deep-Sea Bacterium Photobacterium profundum SS9 Utilizes Separate Flagellar Systems for Swimming and Swarming under High-Pressure Conditions ? †

    Science.gov (United States)

    Eloe, Emiley A.; Lauro, Federico M.; Vogel, Rudi F.; Bartlett, Douglas H.

    2008-01-01

    Motility is a critical function needed for nutrient acquisition, biofilm formation, and the avoidance of harmful chemicals and predators. Flagellar motility is one of the most pressure-sensitive cellular processes in mesophilic bacteria; therefore, it is ecologically relevant to determine how deep-sea microbes have adapted their motility systems for functionality at depth. In this study, the motility of the deep-sea piezophilic bacterium Photobacterium profundum SS9 was investigated and compared with that of the related shallow-water piezosensitive strain Photobacterium profundum 3TCK, as well as that of the well-studied piezosensitive bacterium Escherichia coli. The SS9 genome contains two flagellar gene clusters: a polar flagellum gene cluster (PF) and a putative lateral flagellum gene cluster (LF). In-frame deletions were constructed in the two flagellin genes located within the PF cluster (flaA and flaC), the one flagellin gene located within the LF cluster (flaB), a component of a putative sodium-driven flagellar motor (motA2), and a component of a putative proton-driven flagellar motor (motA1). SS9 PF flaA, flaC, and motA2 mutants were defective in motility under all conditions tested. In contrast, the flaB and motA1 mutants were defective only under conditions of high pressure and high viscosity. flaB and motA1 gene expression was strongly induced by elevated pressure plus increased viscosity. Direct swimming velocity measurements were obtained using a high-pressure microscopic chamber, where increases in pressure resulted in a striking decrease in swimming velocity for E. coli and a gradual reduction for 3TCK which proceeded up to 120 MPa, while SS9 increased swimming velocity at 30 MPa and maintained motility up to a maximum pressure of 150 MPa. Our results indicate that P. profundum SS9 possesses two distinct flagellar systems, both of which have acquired dramatic adaptations for optimal functionality under high-pressure conditions. PMID:18723648

  6. Desulfurization under Conditions of Substoichiometric Pressurized Fluidized Bed Combustion of Coal - Comparison with TG-Tests and Equilibrium Limits.

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Hartman, Miloslav; ?ermák, Ji?í; Poho?elý, Michael

    2001-01-01

    Ro?. 11, ?. 120 (2001), s. 39-53. ISSN 1211-1929 R&D Projects: GA AV ?R IAA4072801; GA MŠk OK 349 Institutional research plan: CEZ:AV0Z4072921 Keywords : desulfurization * sub-stoichiometric * pressurized fluidized bed combustion Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. High-pressure behavior and crystal–fluid interaction under extreme conditions in paulingite [PAU-topology].

    Czech Academy of Sciences Publication Activity Database

    Gatta, G. D.; Scheidl, K. S.; Pippinger, T.; Skála, Roman; Lee, J.; Miletich, R.

    2015-01-01

    Ro?. 206, April (2015), s. 34-41. ISSN 1387-1811 Institutional support: RVO:67985831 Keywords : paulingite * high pressure * X-ray diffraction * compressibility * crystal–fluid interaction Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.209, year: 2013

  8. Peculiar magnetic properties of Er conditioned Ni43Co7Mn31Ga19 at ambientand hydrostatic pressures.

    Czech Academy of Sciences Publication Activity Database

    Kaštil, J.; Kamarád, Ji?í; Knížek, Karel; Arnold, Zden?k; Javorský, P.

    2013-01-01

    Ro?. 565, JUL (2013), s. 134-138. ISSN 0925-8388 R&D Projects: GA ?R GAP204/12/0692 Institutional support: RVO:68378271 Keywords : Heusler alloys * hydrostatic pressure * magnetism Subject RIV: BE - Theoretical Physics Impact factor: 2.726, year: 2013 www.elsevier.com/locate/jalcom

  9. Using Atmospheric Pressure Tendency to Optimise Battery Charging in Off-Grid Hybrid Wind-Diesel Systems for Telecoms

    Directory of Open Access Journals (Sweden)

    Stephen Daniels

    2013-06-01

    Full Text Available Off grid telecom base stations in developing nations are powered by diesel generators. They are typically oversized and run at a fraction of their rated load for most of their operating lifetime. Running generators at partial load is inefficient and, over time, physically damages the engine. A hybrid configuration uses a battery bank, which powers the telecoms’ load for a portion of the time. The generator only operates when the battery bank needs to be charged. Adding a wind turbine further reduces the generator run hours and saves fuel. The generator is oblivious to the current wind conditions, which leads to simultaneous generator-wind power production. As the batteries become charged by the generator, the wind turbine controller is forced to dump surplus power as heat through a resistive load. This paper details how the relationship between barometric pressure and wind speed can be used to add intelligence to the battery charger. A Simulink model of the system is developed to test the different battery charging configurations. This paper demonstrates that if the battery charger is aware of upcoming wind conditions, it will provide modest fuel savings and reduce generator run hours in small-scale hybrid energy systems.

  10. High-pressure crystal structure of elastically isotropic CaTiO3 perovskite under hydrostatic and non-hydrostatic conditions

    International Nuclear Information System (INIS)

    The structural evolution of orthorhombic CaTiO3 perovskite has been studied using high-pressure single-crystal x-ray diffraction under hydrostatic conditions up to 8.1 GPa and under a non-hydrostatic stress field formed in a diamond anvil cell (DAC) up to 4.7 GPa. Under hydrostatic conditions, the TiO6 octahedra become more tilted and distorted with increasing pressure, similar to other 2:4 perovskites. Under non-hydrostatic conditions, the experiments do not show any apparent difference in the internal structural variation from hydrostatic conditions and no additional tilts and distortions in the TiO6 octahedra are observed, even though the lattice itself becomes distorted due to the non-hydrostatic stress. The similarity between the hydrostatic and non-hydrostatic cases can be ascribed to the fact that CaTiO3 perovskite is nearly elastically isotropic and, as a consequence, its deviatoric unit-cell volume strain produced by the non-hydrostatic stress is very small; in other words, the additional octahedral tilts relevant to the extra unit-cell volume associated with the deviatoric unit-cell volume strain may be totally neglected. This study further addresses the role that three factors-the elastic properties, the crystal orientation and the pressure medium-have on the structural evolution of an orthorhombic perovskite loaded in a DAC under non-hydrostatic conditions. The influence of these factors can be clearly visualizedof these factors can be clearly visualized by plotting the three-dimensional distribution of the deviatoric unit-cell volume strain in relation to the cylindrical axis of the DAC and indicates that, if the elasticity of a perovskite is nearly isotropic as it is for CaTiO3, the other two factors become relatively insignificant. (paper)

  11. Stability of Anthocyanins from Red Grape Skins under Pressurized Liquid Extraction and Ultrasound-Assisted Extraction Conditions

    Directory of Open Access Journals (Sweden)

    Ali Liazid

    2014-12-01

    Full Text Available The stability of anthocyanins from grape skins after applying different extraction techniques has been determined. The following compounds, previously extracted from real samples, were assessed: delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, peonidin 3-glucoside, malvidin 3-glucoside, peonidin 3-acetylglucoside, malvidin 3-acetylglucoside, malvidin 3-caffeoylglucoside, petunidin 3-p-coumaroylglucoside and malvidin 3-p-coumaroylglucoside (trans. The techniques used were ultrasound-assisted extraction and pressurized liquid extraction. In ultrasound-assisted extraction, temperatures up to 75 °C can be applied without degradation of the aforementioned compounds. In pressurized liquid extraction the anthocyanins were found to be stable up to 100 °C. The relative stabilities of both the glycosidic and acylated forms were evaluated. Acylated derivatives were more stable than non-acylated forms. The differences between the two groups of compounds became more marked on working at higher temperatures and on using extraction techniques with higher levels of oxygen in the extraction media.

  12. Siderite at lower mantle conditions and the effects of the pressure-induced spin-pairing transition

    Energy Technology Data Exchange (ETDEWEB)

    Lavina, B.; Dera, P.; Downs, R.T.; Prakapenka, V.; Rivers, M.; Sutton, S.; Nicol, M.; (UNLV); (UC); (Ariz)

    2010-05-04

    Siderite (FeCO{sub 3}) forms a complete solid solution with magnesite (MgCO{sub 3}), the most likely candidate for a mantle carbonate. Our experiments with natural siderite reveal spin pairing of d-orbital electrons of Fe{sup 2+} at 43 GPa, as evidenced by a sharp volume collapse of about 10%. The initially colorless crystals assume an intense green color after the transition, which progressively turns to red above 60 GPa. We present clear evidence for the instability of an intermediate spin state in siderite at ambient temperature. At the transition pressure, domains of high and low spin siderite coexist. The unit cell volume difference between magnesite and siderite is significantly decreased by the spin transition, enhancing the solubility between the two calcite-type minerals. A siderite component in magnesite at lower mantle pressure would significantly increase its density and slightly increase the carbonate bulk modulus.

  13. Siderite at lower mantle conditions and the effects of the pressure-induced spin-pairing transition

    Science.gov (United States)

    Lavina, B.; Dera, P.; Downs, R. T.; Prakapenka, V.; Rivers, M.; Sutton, S.; Nicol, M.

    2009-12-01

    Siderite (FeCO3) forms a complete solid solution with magnesite (MgCO3), the most likely candidate for a mantle carbonate. Our experiments with natural siderite reveal spin pairing of d-orbital electrons of Fe2+ at 43 GPa, as evidenced by a sharp volume collapse of about 10%. The initially colorless crystals assume an intense green color after the transition, which progressively turns to red above 60 GPa. We present clear evidence for the instability of an intermediate spin state in siderite at ambient temperature. At the transition pressure, domains of high and low spin siderite coexist. The unit cell volume difference between magnesite and siderite is significantly decreased by the spin transition, enhancing the solubility between the two calcite-type minerals. A siderite component in magnesite at lower mantle pressure would significantly increase its density and slightly increase the carbonate bulk modulus.

  14. Application of the statistical safety evaluation method to the small break LOCA with high pressure injection failure. Sensitivity analyses to determine the break conditions

    International Nuclear Information System (INIS)

    By applying a statistical safety evaluation method, the uncertainties of best estimate results can be estimated quantitatively, and as a consequence, excessive conservatism can be reasonably removed to obtain evaluation results with enhanced reliability. Application of a statistical evaluation method is being made to analyses of the “low pressure injection by intentional depressurization of the steam generator secondary side” which is an accident management approach in a SBLOCA (small break loss-of-coolant accident) with HPI (high pressure injection) failure. At the time of a SBLOCA, the break conditions such as the break size are important parameters since they influence PCT (peak cladding temperature). In this research, sensitivity analyses about the break size, direction and position were carried out for a system plant under a condition which the start timing of the steam generator secondary side intentional depressurization is severer than an actual abnormal operating condition. From the result of the sensitivity analyses, differences in the phenomena progression which change depending on the break conditions were evaluated, and a 3 inch facing-down break of the cold-leg was determined as the base case of a statistical safety evaluation. (author)

  15. Neural reflex regulation of arterial pressure in pathophysiological conditions: interplay among the baroreflex, the cardiopulmonary reflexes and the chemoreflex

    OpenAIRE

    E.C. Vasquez; S.S. Meyrelles; Mauad, H; Cabral, A.M

    1997-01-01

    The maintenance of arterial pressure at levels adequate to perfuse the tissues is a basic requirement for the constancy of the internal environment and survival. The objective of the present review was to provide information about the basic reflex mechanisms that are responsible for the moment-to-moment regulation of the cardiovascular system. We demonstrate that this control is largely provided by the action of arterial and non-arterial reflexes that detect and correct changes in arterial pr...

  16. Theoretical assessment of boron incorporation in nickel ferrite under conditions of operating nuclear pressurized water reactors (PWRs)

    OpenAIRE

    Rak, Zs; Bucholz, E. W.; Brenner, D. W.

    2014-01-01

    A serious concern in the safety and economy of a pressurized water nuclear reactor is related to the accumulation of boron inside the metal oxide (mostly NiFe${}_{2}$O${}_{4}$ spinel) deposits on the upper regions of the fuel rods. Boron, being a potent neutron absorber, can alter the neutron flux causing anomalous shifts and fluctuations in the power output of the reactor core. This phenomenon reduces the operational flexibility of the plant and may force the down-rating of...

  17. Influence of operating conditions and ammonia injection on the emission of nitrogenous gases from pressurized fluidized bed combustion of coal

    International Nuclear Information System (INIS)

    A coal-fired Pressurized Fluidized Bed Combustor at the Delft University of Technology is being used to study fuel conversion and related environmental aspects. This 'semi-technical' scale combustion test rig with an operating pressure up to 10 bar and a maximum thermal capacity of 1,6 MW is being used to investigate environmental aspects of coal combustion like limiting fly ash concentrations in the flue gas by high temperature/high pressure gas cleaning techniques and the influence of fuel related and operation-dependent parameters on the formation and reduction of noxious oxides, in particular nitrogenous species. The fuels investigated so far were anthracites, bituminous coals and brown coals. The influence of different operating parameters such as coal type, freeboard temperature, pressure and excess air on N2O emissions has been investigated and the effect of Selective Non-Catalytic Reduction (SNCR) using ammonia injection in the exhaust of the combustor on the emission of NO, NO2, CO, NH3 and N2O was determined for a number of mol ratios, injection locations and temperatures using 2 British and 2 German coals. Gas concentrations have been determined at different locations of the PFBC test rig, among others in tile freeboard and downstream of the first cyclone using 'conventional' gas analysis instruments, a Gas Chromatograph (GC) and a Fourier Transform InfraRed (FTIR) spectrometer. The paper describes the PFBC test rmeter. The paper describes the PFBC test rig, the ammonia injection system, the sampling systems and the GC and FTIR gas analysis systems. Practical experience gained so far with these measuring systems will be presented and results of the measurements will be given and discussed

  18. Improvement of Coenzyme Q10 Production: Mutagenesis Induced by High Hydrostatic Pressure Treatment and Optimization of Fermentation Conditions

    OpenAIRE

    Yahong Yuan; Yuting Tian; Tianli Yue

    2012-01-01

    Coenzyme Q10 (CoQ10, ubiquinone), a potent antioxidative dietary supplement, was produced by submerged fermentation using Agrobacterium tumefaciens instead of chemical synthesis or solvent extraction. Agrobacterium tumefaciens 1.2554 was subjected to mutagenesis using a series of treatments including high hydrostatic pressure (HHP) treatment, UV irradiation, and diethyl sulfate (DES) treatment to obtain mutant strains showing higher CoQ10 production than wild-type strains. A mutant strain PK3...

  19. Neural reflex regulation of arterial pressure in pathophysiological conditions: interplay among the baroreflex, the cardiopulmonary reflexes and the chemoreflex

    Scientific Electronic Library Online (English)

    E.C., Vasquez; S.S., Meyrelles; H., Mauad; A.M., Cabral.

    1997-04-01

    Full Text Available The maintenance of arterial pressure at levels adequate to perfuse the tissues is a basic requirement for the constancy of the internal environment and survival. The objective of the present review was to provide information about the basic reflex mechanisms that are responsible for the moment-to-mo [...] ment regulation of the cardiovascular system. We demonstrate that this control is largely provided by the action of arterial and non-arterial reflexes that detect and correct changes in arterial pressure (baroreflex), blood volume or chemical composition (mechano- and chemosensitive cardiopulmonary reflexes), and changes in blood-gas composition (chemoreceptor reflex). The importance of the integration of these cardiovascular reflexes is well understood and it is clear that processing mainly occurs in the nucleus tractus solitarii, although the mechanism is poorly understood. There are several indications that the interactions of baroreflex, chemoreflex and Bezold-Jarisch reflex inputs, and the central nervous system control the activity of autonomic preganglionic neurons through parallel afferent and efferent pathways to achieve cardiovascular homeostasis. It is surprising that so little appears in the literature about the integration of these neural reflexes in cardiovascular function. Thus, our purpose was to review the interplay between peripheral neural reflex mechanisms of arterial blood pressure and blood volume regulation in physiological and pathophysiological states. Special emphasis is placed on the experimental model of arterial hypertension induced by N-nitro-L-arginine methyl ester (L-NAME) in which the interplay of these three reflexes is demonstrable

  20. A practical method for determining reasonable drawdown pressure of horizontal well after breakthrough with bottom-water condition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, D.; Jiang, T.; Feng, J.; Bian, W.; Liu, Y. [Tarim Oilfield Company Exploration and Development Research Inst. (China); Zhao, J. [Southwest Petroleum Inst., Nanchong, Sichuan (China)

    2004-07-01

    Horizontal well technology is widely practiced by the petroleum industry because it can effectively delay the onset of water cresting in bottom-water drive reservoirs. Pressure drawdown is one of the several factors that influences the increased rate of water-cut. In this study, a numerical simulation was performed on the TZ402C reservoir in China's Tarim oilfield which has more than 80 operating horizontal wells. Water breakthrough has occurred in most of the wells and production has declined significantly. Regression analysis was used to determine the relationship between the increased rate of water-cut and the pressure drawdown of a horizontal well after water breakthrough in different water-cut phases. A practical method was then developed to determine the reasonable pressure drawdown of a horizontal well following water breakthrough. The method can also be used for horizontal wells in edge-water drive reservoirs. It can also help determine the total increased rate of water-cut when selecting an appropriate plan for enhanced oil recovery. 16 refs., 1 tab., 10 figs.

  1. Neural reflex regulation of arterial pressure in pathophysiological conditions: interplay among the baroreflex, the cardiopulmonary reflexes and the chemoreflex

    Directory of Open Access Journals (Sweden)

    E.C. Vasquez

    1997-04-01

    Full Text Available The maintenance of arterial pressure at levels adequate to perfuse the tissues is a basic requirement for the constancy of the internal environment and survival. The objective of the present review was to provide information about the basic reflex mechanisms that are responsible for the moment-to-moment regulation of the cardiovascular system. We demonstrate that this control is largely provided by the action of arterial and non-arterial reflexes that detect and correct changes in arterial pressure (baroreflex, blood volume or chemical composition (mechano- and chemosensitive cardiopulmonary reflexes, and changes in blood-gas composition (chemoreceptor reflex. The importance of the integration of these cardiovascular reflexes is well understood and it is clear that processing mainly occurs in the nucleus tractus solitarii, although the mechanism is poorly understood. There are several indications that the interactions of baroreflex, chemoreflex and Bezold-Jarisch reflex inputs, and the central nervous system control the activity of autonomic preganglionic neurons through parallel afferent and efferent pathways to achieve cardiovascular homeostasis. It is surprising that so little appears in the literature about the integration of these neural reflexes in cardiovascular function. Thus, our purpose was to review the interplay between peripheral neural reflex mechanisms of arterial blood pressure and blood volume regulation in physiological and pathophysiological states. Special emphasis is placed on the experimental model of arterial hypertension induced by N-nitro-L-arginine methyl ester (L-NAME in which the interplay of these three reflexes is demonstrable

  2. Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

    Science.gov (United States)

    Russin, W. R.

    1974-01-01

    Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

  3. Si isotope fractionation between Si-poor metal and silicate melt at pressure-temperature conditions relevant to metal segregation in small planetary bodies

    Science.gov (United States)

    Kempl, J.; Vroon, P. Z.; Zinngrebe, E.; van Westrenen, W.

    2013-04-01

    Experimental investigations of Si isotope fractionation between Si-bearing metal alloy and silicate phases have to date been limited to high pressure (1-7 GPa) and high temperature (1800-2200 °C) conditions at highly reducing conditions, to optimize applicability of results to early core formation processes in the Earth. Here, we assess the extent and mechanism of Si isotopic fractionation at conditions relevant to metal segregation in small (km-scale) planetary bodies, using samples obtained from an industrial-scale blast furnace of Tata Steel (IJmuiden, the Netherlands). During the low-pressure, high-temperature process of steelmaking inhomogeneous blast furnace burden consisting of pre- and untreated iron ore, iron silicates and coke is reduced to oxygen fugacities near the C-CO buffer, resulting in the segregation of a metal phase containing only ?0.3 wt% Si. Seven sample sets, each comprising a metal alloy and a silicate slag, were taken during tapping of the blast furnace at tapping temperatures between 1400 °C and 1600 °C. We find large isotopic mass fractionation between metal and silicate, with ?30Sisilicate-metal varying between 0.7‰ and 1.6‰, values that are as high as previously obtained in high-pressure, highly reduced experiments. A model for metal-silicate Si isotope fractionation in blast furnaces can explain both the sense and magnitude of fractionation, if the presence of SiO-bearing vapour is explicitly taken into account. Our data indicate that significant Si isotope fractionation can occur between metal and silicate at low-pressure, high-temperature and only mildly reducing conditions for which Si solubility in molten Fe-rich metal is low. This suggests an important role for SiO at low confining pressures. Our data can be applied to models of aubrite meteorite formation through high-temperature differentiation of an enstatite chondrite parent body. Our calculations suggest a far larger degree of rehomogenisation during differentiation than previously thought on the basis of metal-silicate Si isotopic fractionation measured in natural meteorites that re-equilibrated at low temperature.

  4. Continuous monitoring of natural ventilation pressure at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy research and development facility designed to demonstrate the permanent, safe disposal of US defense-generated transuranic waste. The waste storage horizon is 655 m (2150 ft) below surface in bedded salt. To date the WIPP project has not emplaced any waste. There are three intake shafts used to supply air to the underground. All air is exhausted through a single return shaft. The total design airflow during normal operations is 200 m3/s (424,000 cfm). The ventilation system is designed to provide separate air splits to construction, experimental, and storage activities. Separation is achieved by isolating the storage circuit from the construction or experimental circuits with bulkheads. Any air leakage must be towards the storage area of the facility. Field studies have shown that the pressure differential necessary to maintain the correct leakage direction is susceptible to the effects of natural ventilation; therefore, extensive studies and analyses have been conducted to quantify the natural ventilation effects on the WIPP underground airflow system. A component of this work is a monitoring system designed to measure the air properties necessary for calculation of the natural ventilation pressure (NVP). This monitoring system consists of measuring dry bulb temperature, relative humidity, and barometric pressure at strategic location on surface and underground. The psychometric parametersd underground. The psychometric parameters of the air are measured every fifteen minutes. From these data, trends can be determined showing the impact of NVP on the ventilation system during diurnal variations in surface climate. Both summer and winter conditions have been studied. To the author's knowledge this is the first reported instance of automatic and continuous production of time and temperature variant NVPs. This paper describes the results of the initial monitoring study

  5. Leaf injury characteristics of grassland species exposed to ozone in relation to soil moisture condition and vapour pressure deficit

    International Nuclear Information System (INIS)

    A range of plant species typical of semi-natural grasslands were tested for their sensitivity to short-term ozone injury under normal and reduced irrigation, and in relationship to air vapour pressure deficit. Potted specimens of 24 herbs, legumes and grasses were exposed during two seasons to four O3 treatments in open-top chambers. The ozone treatments were: (a) charcoal-filtered air; (b) charcoal-filtered air plus ozone to match ambient levels; (c) charcoal-filtered air plus O3 to ambient levels 1.5 and (d) charcoal-filtered air with ozone added to twice ambient levels during selected episodes of 7–13 d. During these ozone episodes, half of the plants in each ozone treatment received reduced irrigation (dry treatment) while the rest was kept under full irrigation (wet treatment). Type and date of first occurrence of leaf injury were noted during individual growth periods. Plants were harvested three times per year, and the percentage of injured leaves was recorded. Depending on species, injury symptoms were expressed as flecking (O3-specific injury), leaf yellowing or anthocyanin formation. Carum carvi and most species of the Fabaceae family (Onobrychis sativa, Trifolium repens, Trifolium pratense) were found to be most responsive to O3, injury occurring after only a few days of exposure in treatment (b). An episodic reduction in irrigation tended to reduce the expression of O3-specific symptoms, but onlpecies for which a reduction in soil moisture potential and an associated reduction in stomatal conductance during the dry episodes were observed. In other species, the protection from O3 injury seemed to be of little importance. Using artificial neural networks the injury response of nine species was analysed in relation to Species, stomatal conductance, ozone as AOT40 (accumulated exposure above a threshold of 0.04 ppm for periods with global radiation ? 50 W m?2 (Fuhrer et al., 1997)), mean relative growth rate, air vapour pressure deficit and global radiation. In the model with all factors, Species was most important, and when Species was omitted, stomatal conductance was the most important determinant for leaf injury to occur, whereas mean relative growth rate was less important. With no plant-related factors included, air vapour pressure deficit and AOT40 were of highest importance. Only in eight species was a positive relationship found between these two factors during the five days before the onset of injury, indicating increasing protection from ozone with increasing air vapour pressure deficit in some but not all species. These data show that across a range of grassland species, leaf injury caused by elevated levels of ozone is most likely to occur in species with high stomatal conductance and that protection from ozone during dry periods is species-specific and depends on a reduction in stomatal conductance due to a decreaoisture potential. Protection under increased vapour pressure deficit can occur in some but not all species, depending on the relationship between stomatal conductance and air vapour pressure deficit. (author)

  6. High-pressure deformation of calcite marble and its transformation to aragonite under non-hydrostatic conditions

    Science.gov (United States)

    Hacker, B.R.; Kirby, S.H.

    1993-01-01

    We conducted deformation experiments on Carrara marble in the aragonite and calcite stability fields to observe the synkinematic transformation of calcite to aragonite, and to identify any relationships between transformation and deformation or sample strength. Deformation-induced microstructures in calcite crystals varied most significantly with temperature, ranging from limited slip and twinning at 400??C, limited recrystallization at 500??C, widespread recrystallization at 600 and 700??C, to grain growth at 800-900??C. Variations in confining pressure from 0.3 to 2.0 GPa have no apparent effect on calcite deformation microstructures. Aragonite grew in 10-6-10-7 s-1strain rate tests conducted for 18-524 h at confining pressures of 1.7-2.0 GPa and temperatures of 500-600??C. As in our previously reported hydrostatic experiments on this same transformation, the aragonite nucleated on calcite grain boundaries. The extent of transformation varied from a few percent conversion near pistons at 400??C, 2.0 GPa and 10-4 s-1 strain rate in a 0.8 h long experiment, to 98% transformation in a 21-day test at a strain rate of 10-7 s-7, a temperature of 600??C and a pressure of 2.0 GPa. At 500??C, porphyroblastic 100-200 ??m aragonite crystals grew at a rate faster than 8 ?? 10-1m s-1. At 600??C, the growth of aragonite neoblasts was slower, ???6 ?? 10-1 m s -1, and formed 'glove-and-finger' cellularprecipitation-like textures identical to those observed in hydrostatic experiments. The transformation to aragonite is not accompanied by a shear instability or anisotropic aragonite growth, consistent with its relatively small volume change and latent heat in comparison with compounds that do display those features. ?? 1993.

  7. Modeling the thermal conductivity and shear viscosity of mixtures of methane and n-decane under high pressure and high temperature conditions using molecular simulations

    Science.gov (United States)

    Shelton, John

    2015-03-01

    Atomistic molecular dynamics simulations were carried out at equilibrium to calculate the shear viscosity and thermal conductivity of various mixtures of methane and n-decane within the range of ambient to extreme temperature and pressure conditions (i.e. up to 500 degree F and 35,000 psi). Both a computationally efficient united-atom force field and an all-atom force field were employed in this investigation. A quantitative comparison of the results was performed against experimental values and values predicted from a high temperature - high pressure perturbed chain - statistically associated fluid theory (HPHT PC-SAFT) model. Analysis of the intermolecular structure of the fluid as well as its dynamical characteristics were performed.

  8. Muon capture probability of carbon and oxygen for CO, CO2, and COS under low-pressure gas conditions

    International Nuclear Information System (INIS)

    When a negatively charged muon is stopped in a substance, it is captured by an atom of the substance, and the muonic atom is formed. The muon capture process is significantly affected by the chemical environment of the atom and factors such as molecular structure (chemical effect). In this study, we performed muon irradiation for low-pressure CO, CO2, and COS molecules and measured the muonic X-rays emitted immediately after muon capture by an atom. In this paper, we quantitatively discuss the muon capture probability of each type of atom using the LMM model. (author)

  9. High doses of aldosterone antagonist is a condition of sufficient blood pressure control in bilateral adrenal hyperplasia.

    DEFF Research Database (Denmark)

    Therwani, Safa; Pedersen, Erling Bjerregaard

    2015-01-01

    Primary aldosteronism occurs in 1-10% of hypertensive patients and is classified in adenomas or bilateral adrenal hyperplasia. Computed tomography (CT) or magnetic resonance imaging can be used to discriminate these subtypes and in guiding treatment selection. This case report describes a 65-year-old man with hypertension and hypokalaemia during 25 years. Bilateral adrenal hyperplasia was diagnosed based on a CT, and an oral sodium-loading test with measurement of renin and aldosterone confirmed the diagnosis. Blood pressure and potassium in plasma was normalized during treatment with the mineralocorticoid receptor antagonist eplerenon.

  10. Unique rod lens/video system designed to observe flow conditions in emergency core coolant loops of pressurized water reactors

    International Nuclear Information System (INIS)

    Techniques and equipment are described which are used for video recordings of the single- and two-phase fluid flow tests conducted with the PKL Spool Piece Measurement System designed by Lawrence Livermore Laboratory and EG and G Inc. The instrumented spool piece provides valuable information on what would happen in pressurized water reactor emergency coolant loops should an accident or rupture result in loss of fluid. The complete closed-circuit television video system, including rod lens, light supply, and associated spool mounting fixtures, is discussed in detail. Photographic examples of test flows taken during actual spool piece system operation are shown

  11. Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Intermittency Behavior Along the Suction Surface of a Low Pressure Turbine Blade

    Science.gov (United States)

    Schobeiri, M. T.; Ozturk, B.; Ashpis, David E.

    2007-01-01

    The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the suction surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on suction surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the suction surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re=110,000.

  12. Characterization and Prediction of Subsurface Pneumatic Pressure Variations at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Yucca Mountain, Nevada is being investigated as the proposed site for geologic disposal of high level nuclear waste. A massive data collection effort for characterization of the unsaturated zone is being carried out at the site. The USGS is monitoring the subsurface pressure variations due to barometric pumping in several boreholes. Numerical models are used to simulate the observed subsurface pressure variations. Data inversion is used to characterize the unsaturated system and estimate the pneumatic diffusivity of important geologic features. Blind predictions of subsurface response and subsequent comparison to recorded data have built confidence in the models of Yucca Mountain

  13. High temperature steam oxidation study on Zr–2.5%Nb pressure tube under simulated LOCA condition

    International Nuclear Information System (INIS)

    Study of high temperature steam oxidation kinetics and microstructural evolution during the oxidation was carried out on the coupons of Zr–2.5%Nb pressure tube material of Indian Pressurized Heavy Water Reactors (PHWRs) in the temperature range 500–1050 °C. The oxidation kinetics derived from the weight gain measurements showed a parabolic rate law with the parabolic rate constant KP expressed as an Arrhenius equation KP = 10.12 × 108 × exp(?18664/T). Hydrogen pick up was less than 55 ppm in the samples oxidized at temperatures up to 850 °C but high (250–400 ppm) in the samples oxidized in the ? phase region (900 °C and above). The microstructure of the samples oxidized above the ?-Zr/?-Zr transition temperature showed from the surface inwards sequentially the presence of an oxide layer, an underlying oxygen stabilized ?-Zr layer and a prior ?-Zr phase containing hydride precipitates. An increase in the hardness was observed near the oxide-metal interface in the coupons oxidized above 900 °C, due to formation of oxygen stabilized ?-Zr layer. Higher hardness was also observed in the base metal in the samples oxidized at 1000 °C and 1050 °C

  14. High temperature steam oxidation study on Zr-2.5%Nb pressure tube under simulated LOCA condition

    Science.gov (United States)

    Banerjee, Suparna; Sawarn, Tapan K.; Alur, V. D.; Rath, B. N.; Kaity, Santu; Pandit, K. M.; Anantharaman, S.; Sah, D. N.

    2013-08-01

    Study of high temperature steam oxidation kinetics and microstructural evolution during the oxidation was carried out on the coupons of Zr-2.5%Nb pressure tube material of Indian Pressurized Heavy Water Reactors (PHWRs) in the temperature range 500-1050 °C. The oxidation kinetics derived from the weight gain measurements showed a parabolic rate law with the parabolic rate constant KP expressed as an Arrhenius equation KP = 10.12 × 108 × exp(-18664/T). Hydrogen pick up was less than 55 ppm in the samples oxidized at temperatures up to 850 °C but high (250-400 ppm) in the samples oxidized in the ? phase region (900 °C and above). The microstructure of the samples oxidized above the ?-Zr/?-Zr transition temperature showed from the surface inwards sequentially the presence of an oxide layer, an underlying oxygen stabilized ?-Zr layer and a prior ?-Zr phase containing hydride precipitates. An increase in the hardness was observed near the oxide-metal interface in the coupons oxidized above 900 °C, due to formation of oxygen stabilized ?-Zr layer. Higher hardness was also observed in the base metal in the samples oxidized at 1000 °C and 1050 °C.

  15. Pressure Fluctuations on the Bed of Surge Tank at the H.P. Zimapan, Hgo., with Different Arrangements Studied on Hydraulic Model, with the Lowest Operation Conditions

    Directory of Open Access Journals (Sweden)

    H. Marengo–Mogollón

    2009-10-01

    Full Text Available In this paper, the pressure fluctuations of the surge tank in the Zimapan Hydroelectric Project are compared in a hydraulic model. The shaft is located lateral, over the conduction tunnel and in the simple form (permitting the tunnel entering the shaft, with and without orifice plates taking into account the demand and supply condition of energy with the minimum level of water of the conduction. It was determined the hydraulic efficiency and it was found that it was the best constructive option.

  16. Volume reduction on all particle size of the contaminated soil. Continuous processing technology of attrition, chemical wash under an ambient temperature and pressure condition and magnetic separation

    International Nuclear Information System (INIS)

    An examination was conducted in order to establish a practical purification system that could largely reduce the storage volume of radioactive waste in the Intermediate Storage Facility. The examination consists of a 3-step washing treatment of contaminated soil, which includes “Milling Washing” of removed contaminated soil, chemical extraction of fine soil fraction resulted from the “Milling Washing” under an ambient temperature and pressure condition, and magnetic separation of cesium from the extracted solution. As a result of the examination, we succeeded in development of a safe system with low initial cost and running cost. (author)

  17. Evolution of the Active Phase of CoMo/Al2O3 Catalysts under Industrial Conditions: a High-Pressure MES Study

    Science.gov (United States)

    Dugulan, A. I.; Overweg, A. R.; Crajé, M. W. J.; Kearley, G. J.

    2005-04-01

    The behavior of CoMo/Al2O3 catalysts sulfided in H2S/H2 gas mixture, under industrial conditions, was investigated using Mössbauer emission spectroscopy (MES). An intermediate Co-Mo phase is formed after increasing the sulfidation pressure to 4 MPa, favoring the Co-Mo-S phase formation. An increase in the quadrupole splitting value of the Co-sulfide species after treatment at 573 K is proposed as a prerequisite for the formation of ideal Co-Mo-S structures.

  18. The Costs of Parental Pressure to Express Emotions: Conditional Regard and Autonomy Support as Predictors of Emotion Regulation and Intimacy

    Science.gov (United States)

    Roth, Guy; Assor, Avi

    2012-01-01

    This research focuses on offspring's perceptions of their parents' usage of conditional regard and autonomy-supportive practices in response to the offspring's experiences of negative emotion. Participants were 174 college students (60% were females). As predicted from self-determination theory (Ryan & Deci, 2000), students' perceptions of parents…

  19. A simplified hydrokinetic model for a steady-state microwave discharge sustained by traveling waves at atmospheric pressure conditions

    Science.gov (United States)

    Gordillo-Vázquez, F. J.; Cotrino, J.

    1995-10-01

    The properties of a microwave-induced argon plasma produced by traveling surface wave at atmospheric pressure are investigated theoretically. A hydrokinetic model is elaborated to obtain the nonequilibrium one-dimensional profiles of electron temperature Te (average electron energy), electron density ne, and the first excited state population density n4s, along the axis of a steady-state discharge. A three-level atomic structure is assumed for the argon atom. A particle balance is included through the continuity equations for ne and n4s. These equations are coupled with an energy balance equation for the electrons. The effects of different parameters on the properties of the argon discharge are investigated: discharge tube radius, gas flow rate, resonant radiation-escape factor, and neutral gas temperature.

  20. Analysis of blood pressure–heart rate feedback regulation under non-stationary conditions: beyond baroreflex sensitivity

    International Nuclear Information System (INIS)

    The feedback regulation of blood pressure and heart rate is an important indicator of human autonomic function usually assessed by baroreflex sensitivity (BRS). We suggest a new method yielding a higher temporal resolution than standard BRS methods. Our approach is based on a regression analysis of the first differences of inter-heartbeat intervals and blood pressure values. Data are recorded from 23 patients with hypertension and sleep apnoea, 22 patients with diabetes mellitus and 23 healthy subjects. Using the proposed method for 3 min data segments, we obtain average regression coefficients of 9.1 and 3.5 ms mmHg?1 for healthy subjects in supine and orthostatic positions, respectively. In patients with hypertension, we find them to be 3.8 and 2.6 ms mmHg?1. The diabetes patients with and without autonomic neuropathy are characterized by 3.1 and 6.1 ms mmHg?1 in the supine position compared with 1.7 and 3.3 ms mmHg?1 in the orthostatic position. The results are highly correlated with conventional BRS measures; we find r > 0.9 for the dual sequence method. Therefore, we suggest that the new method can quantify BRS. It is superior in distinguishing healthy subjects from patients both in supine and orthostatic positions for short-term recordings. It is suitable for non-stationary data and has good reproducibility. Besides, we cannot exclude that other regulatory mechanisms than BRS may also contribute to the regression coefficients between the first differences

  1. BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Prince William Sound (Gulf of Alaska) from 19890505 to 19890511 (NODC Accession 8900192)

    National Oceanic and Atmospheric Administration, Department of Commerce — The University of Alaska, Institute of Marine Science is responsible for this data collected aboard the R/V Alpha Helix on cruise number HX123 between May 5, 1989...

  2. Determination of molecular surface structure, composition, and dynamics under reaction conditions at high pressures and at the solid-liquid interface.

    Science.gov (United States)

    Somorjai, Gabor A; Beaumont, Simon K; Alayoglu, Selim

    2011-10-17

    In the last two decades, surface-science experiments and techniques have been developed to focus on obtaining molecular information under reaction conditions at high pressures (near or above 1 bar) and liquid interfaces. This Minireview describes the results of these studies obtained by surface-sensitive laser spectroscopies, scanning tunneling microscopy, and X-ray spectroscopies usually practiced at a synchrotron light source. The use of model surfaces, single crystals, and monodisperse nanoparticles with variable size (1-10 nm) and shape facilitates meaningful interpretation of the experimental data. These methods allow evaluation of the molecular structures of intermediates, oxidation states of metals, and mobility of adsorbants. New techniques that are likely to make major contributions to the investigation of surfaces under reaction conditions are also discussed. PMID:21626616

  3. Gas chromatography for in situ analysis of a cometary nucleus V. Study of capillary columns' robustness submitted to long-term reduced environmental pressure conditions.

    Science.gov (United States)

    Szopa, C; Sternberg, R; Coscia, D; Goesmann, F; Gomes, R; Legrand, S; Jerome, M; Meierhenrich, U J; Raulin, F

    2014-11-14

    With the European Space Agency's Rosetta space mission to comet 67P/Churyumov-Gerasimenko, a gas chromatograph, part of the COmetary Sampling And Composition (COSAC) experiment, travelled for about 10 years in the interplanetary medium before operating at the surface of the cometary nucleus in November 2014. During its journey in space, the instrument was exposed to the constraining conditions of the interplanetary medium, including reduced environmental pressures. In order to estimate the potential influence of this severe condition on the chromatographic capillary columns, their stationary phase and the subsequent separation capability, a set of flight spare columns were kept under reduced environmental pressure in the laboratory for the same duration as the probe sent to the comet. The columns' analytical performances were evaluated recently and compared to the original ones obtained just before the launch of the Rosetta probe. The results presented here show that the chromatographic performances of the spare chromatographic columns were not altered in time. From this result, it can be expected that the flight instrument will perform nominally for the analysis of the first cometary nucleus sample to be collected ever, and that the preparation of the interpretation of the data to be taken at the cometary surface nucleus can be done through calibration of these spare columns, and other spare components of the instrument. PMID:25441355

  4. Measurement of local void fraction distribution in rod bundle under high-pressure high-temperature boil-off conditions by using optical void probe

    International Nuclear Information System (INIS)

    Local void fractions along a bundle diameter were measured with an optical void probe for steam-water two-phase flow without heat input from heated rods at 3.0 MPa, simulating boil-off (very-low flow) conditions which are of importance in a small-break loss-of-coolant accident (LOCA) of a nuclear reactor. The test conditions covered mass fluxes from 10.6 to 90.3 kg/m2s and qualities from 0.061 to 0.770. The local void-fraction distribution shifted from a convex-shape to a flat-shape, when the flow pattern changed from a bubbly flow to an annular flow. The difference between a differential-pressure-based (volume-averaged) void fraction and a gamma-densitometer-based (chordally-averaged) void fraction could be explained qualitatively mainly by local void-fraction distributions both in each subchannel and in the entire bundle. It should be examined whether differential pressure measurements, which have been used to develop existing void-fraction correlations or models, provide exact volume-averaged void fractions or not. (author)

  5. Potential overdesign for the extreme load condition: current Pressure Vessel Research Committee Technical Committee on Piping Systems activities

    International Nuclear Information System (INIS)

    A major concern of some members of the industry has been the increased rigidity of piping systems resulting from seismic and other dynamic load requirements and the response of the designer to those requirements. Note that the concern is two-fold: (1) requirements and (2) industry response. After years of concern being voiced and the presentation of papers and reports in the public forum the industry formed a special committee under the auspices of the Pressure Vessel Research Committee. This is not to say that substantial activities were not underway or completed by other investigators and organizations because they were. What was needed was an organization to review all the completed and ongoing activities as well as determine those areas which were most susceptible to modification. The Steering Committee on Piping Systems was organized and proceeded to appoint a Technical Committee on Piping Systems (the Committee) to perform the technical review of current data requirements, Codes, Regulations, etc., and make recommendations for modifications. The Steering Committee is an oversight group as well as having significant potential for making changes occur in the appropriate Codes or Regulations. The Committee is currently looking at four major areas: (1) damping values; (2) spectra; (3) dynamic stress criteria; and (4) industry practice

  6. Simple evaluation method for temperature drop at contact interface between rough surfaces under low contact pressure conditions

    Science.gov (United States)

    Tomimura, Toshio; Takahashi, Yasuo; Do, Tae Wan; Shigyo, Kensei; Koito, Yasushi

    2014-08-01

    For heat removal from systems such as electronic equipment, satellite thermal control systems, and nuclear reactors, reduction of thermal contact resistance (TCR) is the most crucial issue to be addressed. Several studies have attempted to propose evaluation equations for predicting TCR for flat rough surfaces. However, as is well known, there are still wide discrepancies among measured results, even for similar materials. In this study, based on the conventional unit cell model for flat surfaces with roughness and the newly proposed contact surface model for wavy surfaces with roughness, thermal contact resistance under a low contact pressure of 0.I-I.0 MPa is investigated theoretically and experimentally. Comparison of the measured and calculated results shows that the measured temperature drop at the interface (that is, the thermal contact resistance) between flat surfaces with roughness lies between the values evaluated by the unit cell model for the cases with and without the heat flow constriction. Furthermore, when the rough surface has waviness, the introduction of macroscopic constriction resistance is shown to be important for evaluating the temperature drop at the interface.

  7. Reaction kinetics and solubilities of corrosion products in the physicochemical conditions of the primary circuit of pressurized water reactors (PWR)

    International Nuclear Information System (INIS)

    A better understanding of the behavior of the corrosion products at operating conditions of PWR is required. This study aims to collect new thermodynamic data on the species composing the corrosion products. The experimental work, described in this paper, focuses on the study of two solid phases: nickel oxide NiO and nickel ferrite NiFe2O4. Dissolution rate of nickel oxide has been measured to 130 C in acidic conditions (pH 3 to 5). A kinetic model has been used to describe the measured dissolution rates. This calculation allowed us to determine the real activation energy of the dissolution reaction of nickel oxide which is equal to 56,5 ± 3,7 kJ.mol-1. The dissolution rates of nickel oxide are slow and as a consequence, only a limited amount of nickel oxide can be dissolved during reactor shutdown. Solubility of a stoichiometric nickel ferrite, experimentally synthesized, has been measured from 100 to 200 C in acidic conditions with a hydrogen electrode concentration cell. The results show a non-congruent dissolution of nickel ferrite with an iron excess. The speciation of soluble iron and nickel was studied based on the available thermodynamic data at high temperature and the measured concentrations were compared with the equilibrium constants with the MULTEQ code. The solubility of nickel ferrite in a reducing acidic solution is reasonably well described by the available thermodynamic data. A new high temperature solubility measurement cell was designed and built. This paper describes in detail the design of the cell and the first tests that have been conducted. (author)

  8. Experiments of CHF and ONB in a finned rod bundle under low flow and low pressure conditions

    International Nuclear Information System (INIS)

    Rod bundle CHF tests were performed under low flow conditions to supplement the CHF data for HANARO fuel. The test rod had the same geometric configuration as the real HANARO fuel and the aluminium cladding with fins is co-extruded on the stainless steel heating tube. There are 3 types of test sections of which shapes are hexagonal with 7 rods, triangular with 3 rods and rectangular with 4 rods. A test bundle has 3 spacers axially and a view window is located in the upper region of the test section. Flow patterns until the CHF condition are typically varied from bubbly flow to annular flow and then CHF occurs through the long annular flow period. A total of 36 bundle CHF data was obtained in 3 test sections. The results showed that the bundle CHF data is larger than the single rod CHF data by 4% ? 32%. It is considered that these results are induced by the enhancement of the turbulence and thermal mixing generated by the spacers. In addition, measurement of the ONB in the rectangular bundle was attempted using sound signals. A hydrophone was attached to near the outlet wall of the test section. Hydrophone signals around the ONB point were measured and analyzed based on the frequency through the real FFT. Frequency analysis showed clear differences in the PSDs for 3 different frequency ranges before and after ONB. This behaviour was reproduced for different flow rates. (author)

  9. On-line surveillance instrumentation for full scale thermal shock trials under real pressurized water conditions (German HDR-program)

    International Nuclear Information System (INIS)

    Thermal shock tests on a saturated steam outlet nozzle edge have been conducted under simulated realistic operation conditions (T = 3000C, p = 11 MPa) for the past three years. The tests are to improve our understanding of crack formation and crack growth under thermal shock conditions and to evaluate and improve the suitability of non-destructive test methods for the on-line surveillance, the detection and quantitative description of natural cracks and crack fields. For on-line monitoring of the thermal shock tests conducted on the A2 nozzle, thermocouples and strain gauges (both on the inside and the outside), clip gauges (CMOD measurement), stationary US-probes, the potential drop technique (potential measurement on the inside), and acoustic emission tests have been used. In the final two test phases (approx. 800 load cycles) by a new six-channel R and D acoustic emission analysis system (signal parameter processor) developed and built at IzfP has been applied. (orig./HP)

  10. Monitoring of prestressed concrete pressure vessels. II. performance of selected concrete embedment strain meters under normal and extreme environmental conditions

    International Nuclear Information System (INIS)

    Unique types of instrumentation are used in prestressed concrete pressure vessels (PCPVs) to measure strains, stresses, deflections, prestressing forces, moisture content, temperatures, and possibly cracking. Their primary purpose is to monitor these complex structures throughout their 20- to 30-year operating lifetime in order to provide continuing assurance of their reliability and safety. Numerous concrete embedment instrumentation systems are available commercially. Since this instrumentation is important in providing continuing assurance of satisfactory performance of PCPVs, the information provided must be reliable. Therefore, laboratory studies were conducted to evaluate the reliability of these commercially available instrumentation systems. This report, the second in a series related to instrumentation embedded in concrete, presents performance-reliability data for 13 types of selected concrete embedment strain meters which were subjected to a variety of loading environments, including unloaded, thermally loaded, simulated PCPV, and extreme environments. Although only a limited number of meters of each type were tested in any one test series, the composite results of the investigation indicate that the majority of these meters would not be able to provide reliable data throughout the 20- to 30-year anticipated operating life of a PCPV. Specific conclusions drawn from the study are: (1) Improved corrosion-resistant materials and sealing techniques should be developed for meters that are to be used in PCPV environments. (2) There is a need for the development of meters that are capable of surviving in concretes where temperatures in excess of 660C are present for extended periods of time. (3) Research should be conducted on other measurement techniques, such as inductance, capacitance, and fluidics

  11. A priori and a posteriori investigations for developing large eddy simulations of multi-species turbulent mixing under high-pressure conditions

    Science.gov (United States)

    Borghesi, Giulio; Bellan, Josette

    2015-03-01

    A Direct Numerical Simulation (DNS) database was created representing mixing of species under high-pressure conditions. The configuration considered is that of a temporally evolving mixing layer. The database was examined and analyzed for the purpose of modeling some of the unclosed terms that appear in the Large Eddy Simulation (LES) equations. Several metrics are used to understand the LES modeling requirements. First, a statistical analysis of the DNS-database large-scale flow structures was performed to provide a metric for probing the accuracy of the proposed LES models as the flow fields obtained from accurate LESs should contain structures of morphology statistically similar to those observed in the filtered-and-coarsened DNS (FC-DNS) fields. To characterize the morphology of the large-scales structures, the Minkowski functionals of the iso-surfaces were evaluated for two different fields: the second-invariant of the rate of deformation tensor and the irreversible entropy production rate. To remove the presence of the small flow scales, both of these fields were computed using the FC-DNS solutions. It was found that the large-scale structures of the irreversible entropy production rate exhibit higher morphological complexity than those of the second invariant of the rate of deformation tensor, indicating that the burden of modeling will be on recovering the thermodynamic fields. Second, to evaluate the physical effects which must be modeled at the subfilter scale, an a priori analysis was conducted. This a priori analysis, conducted in the coarse-grid LES regime, revealed that standard closures for the filtered pressure, the filtered heat flux, and the filtered species mass fluxes, in which a filtered function of a variable is equal to the function of the filtered variable, may no longer be valid for the high-pressure flows considered in this study. The terms requiring modeling are the filtered pressure, the filtered heat flux, the filtered pressure work, and the filtered species mass fluxes. Improved models were developed based on a scale-similarity approach and were found to perform considerably better than the classical ones. These improved models were also assessed in an a posteriori study. Different combinations of the standard models and the improved ones were tested. At the relatively small Reynolds numbers achievable in DNS and at the relatively small filter widths used here, the standard models for the filtered pressure, the filtered heat flux, and the filtered species fluxes were found to yield accurate results for the morphology of the large-scale structures present in the flow. Analysis of the temporal evolution of several volume-averaged quantities representative of the mixing layer growth, and of the cross-stream variation of homogeneous-plane averages and second-order correlations, as well as of visualizations, indicated that the models performed equivalently for the conditions of the simulations. The expectation is that at the much larger Reynolds numbers and much larger filter widths used in practical applications, the improved models will have much more accurate performance than the standard one.

  12. Structural characterization of magnesium-based compounds Mg9Si5 and Mg4Si3Al (superconductor) synthesized under high pressure and high temperature conditions.

    Science.gov (United States)

    Ji, Shidong; Imai, Motoharu; Zhu, Haikui; Yamanaka, Shoji

    2013-04-01

    Two kinds of magnesium-based compounds Mg9Si5 and Mg4Si3Al have been prepared under high pressure and high temperature (HPHT) conditions of 5 GPa at 900-1100 °C. Single crystal study revealed that Mg9Si5 crystallizes in space group P6(3) (No. 173) with the lattice parameters a = 12.411(1) Å, c = 12.345(1) Å, and Z = 6. The structure can be derived from the high pressure form Mg2Si with the anticotunnite structure; excess Si atoms of Mg9Si5 form Si-Si pairs in the prismatic cotunnite columns running along the c axis. Mg4Si3Al is obtained by a rapid cooling of a ternary mixture Mg:Al:Si = 1:1:1 from ~800 °C to room temperature under a pressure of 5 GPa. The compound crystallizes in space group P4/ncc (No. 130) with the lattice parameters a = 6.7225(5) Å, c = 13.5150(9) Å, and Z = 4. The structure consists of an alternate stacking of [AlSi2] layers having a Cairo pattern and [Mg4Si] antitetragonal prismatic layers. It can be viewed as composed of hexa-Si-capped tetragonal prismatic cages Mg8Si6 with an Al atom at the center of each cage, Al@Mg8Si6. The compound shows superconductivity with a transition temperature Tc = 5.2 K. The formation regions of the two kinds of new magnesium-based compounds have been proposed. PMID:23477562

  13. The muscle ankyrin repeat proteins CARP, Ankrd2, and DARP are not essential for normal cardiac development and function at basal conditions and in response to pressure overload.

    Science.gov (United States)

    Bang, Marie-Louise; Gu, Yusu; Dalton, Nancy D; Peterson, Kirk L; Chien, Kenneth R; Chen, Ju

    2014-01-01

    Ankrd1/CARP, Ankrd2/Arpp, and Ankrd23/DARP belong to a family of stress inducible ankyrin repeat proteins expressed in striated muscle (MARPs). The MARPs are homologous in structure and localized in the nucleus where they negatively regulate gene expression as well as in the sarcomeric I-band, where they are thought to be involved in mechanosensing. Together with their strong induction during cardiac disease and the identification of causative Ankrd1 gene mutations in cardiomyopathy patients, this suggests their important roles in cardiac development, function, and disease. To determine the functional role of MARPs in vivo, we studied knockout (KO) mice of each of the three family members. Single KO mice were viable and had no apparent cardiac phenotype. We therefore hypothesized that the three highly homologous MARP proteins may have redundant functions in the heart and studied double and triple MARP KO mice. Unexpectedly, MARP triple KO mice were viable and had normal cardiac function both at basal levels and in response to mechanical pressure overload induced by transverse aortic constriction as assessed by echocardiography and hemodynamic studies. Thus, CARP, Ankrd2, and DARP are not essential for normal cardiac development and function at basal conditions and in response to mechanical pressure overload. PMID:24736439

  14. Estimation of temperature-induced reactor coolant system and steam generator tube creep rupture probability under high-pressure severe accident conditions

    International Nuclear Information System (INIS)

    A severe accident has inherently significant uncertainties due to the complex phenomena and wide range of conditions. Because of its high temperature and pressure, performing experimental validation and practical application are extremely difficult. With these difficulties, there has been few experimental researches performed and there is no plant-specific experimental data. Instead, computer codes have been developed to simulate the accident and have been used conservative assumptions and margins. This study is an effort to reduce the uncertainty in the probabilistic safety assessment and produce a realistic and physical-based failure probability. The methodology was developed and applied to the OPR1000. The creep rupture failure probabilities of reactor coolant system (RCS) components were evaluated under a station blackout severe accident with all powers lost and no recovery of steam generator auxiliary feed-water. The MELCOR 1.8.6 code was used to obtain the plant-specific pressure and temperature history of each part of the RCS and the creep rupture failure times were calculated by the rate-dependent creep rupture model with the plant-specific data. (author)

  15. Development of drift-flux model based on 8 x 8 BWR rod bundle geometry experiments under prototypic temperature and pressure conditions

    International Nuclear Information System (INIS)

    The drift-flux model is one of the imperative concepts used to consider the effects of phase coupling on two-phase flow dynamics. Several drift-flux models are available that apply to rod bundle geometries and some of these are implemented in several nuclear safety analysis codes. However, these models are not validated by well-designed prototypic full bundle test data, and therefore, the scalability of these models has not necessarily been verified. The Nuclear Power Engineering Corporation (NUPEC) conducted void fraction measurement tests in Japan with prototypic 8 x 8 BWR (boiling water reactor) rod bundles under prototypic temperature and pressure conditions. Based on these NUPEC data, a new drift-flux model applicable to predicting the void fraction in a rod bundle geometry has been developed. The newly developed drift-flux model is compared with the other existing data such as the two-phase flow test facility (TPTF) data taken at the Japan Atomic Energy Research Institute (JAERI) [currently, Japan Atomic Energy Agency (JAEA)] and low pressure adiabatic 8 x 8 bundle test data taken at Purdue University in the United States. The results of these comparisons show good agreement between the test data and the predictions. The effects of power distribution, spacer grids, and the bundle geometry on the newly developed drift-flux model have been discussed using the NUPEC data. (author)

  16. Application of Structural Reliability to support deterministic integrity analyses of Reactor Pressure Vessel subjected to transient conditions

    International Nuclear Information System (INIS)

    The benefits of a probabilistic approach compared to the more conventional deterministic method are the clear treatment of uncertainties and the possibility to perform sensitivity studies from which it is possible to identify and quantify the effect of key factors and mitigative actions. They thus provide information to support optimal decisions related to in-service inspection planning and maintenance strategies, lifetime prediction or reassessment, integrity assessment of degradation and definition of in-service acceptability criteria. Apart from a clear modelling of fracture mechanics concept and detailed knowledge of the input data, application of this type of analysis requires a tool capable of making a reasonably easy numerical estimate of the probability of failure. For this purpose a benchmark problem has been performed by EDF, Framatome and CEA to clarify the difficulties and differences in numerical processes. In this study, general state-of-the-art structural reliability methods known as First and Second Order Reliability Methods (FORM/SORM) along with Monte Carlo Simulation and Importance Sampling were tested on a rather complex mechanical model. This model concerns the risk of brittle rupture of a PWR vessel subjected to transient conditions. The objective of this paper is to present the results of this benchmark exercises used also to validate the probabilistic model and its input random parameters. By performing sensitivity studies and analyzing the coo sensitivity studies and analyzing the coordinate value of the design point (most probable failure point given by FORM method), the most influential parameters have been identified on this case study. Special data base have therefore been collected and sophisticated statistical treatment performed to update more precisely the probability distribution of these parameters (the fracture toughness transition curve, the irradiation-induced shift prediction, the flaw size, the reliability of NDE...). Results from these probabilistic analyses can now be used to calibrate explicit safety factors in relation to implicit safety margins, and define in-service acceptability criteria. The 'deterministic' approach is then treated as a special case of the more detailed 'probabilistic' formulation of the problem

  17. Experiments of CHF and ONB in a finned rod bundle under low flow and low pressure conditions

    International Nuclear Information System (INIS)

    This paper presents the experimental results for ONB and CHF measurements in a finned rod bundle at low flow conditions. Test was performed to supplement CHF data for HANARO fuel in a low flow region. A test bundle comprised of several finned rods was designed to have the same geometric characteristics of the HANARO fuel. For the experiments, 3 types of test sections, whose shapes are hexagonal with 7 rods, triangular with 3 rods and rectangular with 4 rods, were used. It is difficult to find out the accurate ONB and CHF point in a bundle because the growth of void and the occurrence of dryout inside can not be visual. So, thermocouples were attached to the end of each fuel rods for detecting the CHF and a transparent window was made in the upper region of the test section to know the ONB point together with the coolant behavior during both tests. To supplement the detection of ONB point, a microphone was also attached to the wall of test section together with the amplifier of sound signal. The physical phenomena and flow patterns were observed with the support of a high-speed camera system during the experiments. Roughly speaking, CHF seems to be occurred in the annular flow regime when the heat flux is high enough to evaporate the water film near the top of heater before the surface is continuously cooled by the periodic chugging water. The parametric trends on the inlet temperature and mass flux for the obtained data are same as those of CHF characteristics well knme as those of CHF characteristics well known in the text. The measured heat flux of ONB and CHF were compared with those in a single pin of same geometry. For CHF data, bundle CHF data seems to be larger than that of a single rod CHF data by 4% ? 32%. It is considered that these results are induced by the enhancement of turbulence and thermal mixing generated by spacers that were not attached in the single pin test

  18. The determination of equivalent bearing loading for the BSMT that simulate SSME high pressure oxidizer turbopump conditions using the SHABERTH/SINDA computer programs

    Science.gov (United States)

    Mcdonald, Gary H.

    1987-01-01

    The MSFC bearing seal material tester (BSMT) can be used to evaluate the SSME high pressure oxygen turbopump (HPOTP) bearing performance. The four HPOTP bearings have both an imposed radial and axial load. These radial and axial loads are caused by the HPOTP's shaft, main impeller, preburner impeller, turbine and by the LOX coolant flow through the bearings, respectively. These loads coupled with bearing geometry and operating speed can define bearing contact angle, contact Hertz stress, and heat generation rates. The BSMT has the capability of operating at HPOTP shaft speeds, provide proper coolant flowrates but can only apply an axial load. Due to the inability to operate the bearings in the BSMT with an applied radial load, it is important to develop an equivalency between the applied axial loads and the actual HPOTP loadings. A shaft-bearing-thermal computer code (SHABERTH/SINDA) is used to simulate the BSMT bearing-shaft geometry and thermal-fluid operating conditions.

  19. Porous material characterization--ultrasonic method for estimation of tortuosity and characteristic length using a barometric chamber.

    Science.gov (United States)

    Moussatov, A; Ayrault, C; Castagnède, B

    2001-04-01

    An ultrasonic method of acoustic parameter evaluation for porous materials saturated by air (or any other gas) is discussed. The method is based on the evolution of speed of sound and the attenuation inside the material when the static pressure of the gas saturating the material is changed. Asymptotic development of the equivalent fluid model of Johnson-Allard is used for analytical description. The method allows an estimation of three essential parameters of the model: the tortuosity, and the viscous and thermal characteristic lengths. Both characteristic lengths are estimated individually by assuming a given ratio between them. Tests are performed with industrial plastic foams and granular substances (glass beads, sea sand) over a gas pressure range from 0.2 to 6 bars at the frequencies 30-600 kHz. The present technique has a number of distinct advantages over the conventional ultrasonic approach: operation at a single frequency, improved signal-to-noise ratio, possibility of saturation the porous media by different gases. In the case when scattering phenomena occur, the present method permits a separate analysis of scattering losses and viscothermal losses. An analytical description of the method is followed by a presentation of the set-up and the measurement procedure. Experimental results and perspectives are discussed. PMID:11350000

  20. Role of pore fluid pressure on transient strength changes and fabric development during serpentine dehydration at mantle conditions: Implications for subduction-zone seismicity

    Science.gov (United States)

    Proctor, Brooks; Hirth, Greg

    2015-07-01

    To further investigate the dehydration embrittlement hypothesis and its possible link to subduction-zone seismicity, we conducted deformation experiments on antigorite serpentinite in a Griggs-type apparatus at conditions below and above antigorite stability. Temperature ramps (crossing the antigorite thermal stability) were used in conjunction with a new experimental method that allows fluid produced during dehydration reactions to be drained, partially drained or undrained. During temperature ramps, weakening coupled with transient slip initiated at ? 650 °C, coincident with the predicted phase transition of antigorite to olivine and talc at ? 1 GPa. The weakening-rate and steady-state strength were dependent on drainage conditions; undrained samples weakened over a few minutes and supported the lowest shear stress (? 50 MPa), while drained samples weakened over a few hours and supported the highest shear stress (? 210 MPa). The coefficient of friction (shear stress over normal stress) in drained samples decreased from ?0.4 to ?0.16 after the temperature ramp. The strengths of samples that were first annealed at 700 °C for ? 12 h, then deformed, were similar to those observed in the temperature ramp experiments. Strain localization along fractures occurred in all samples during temperature ramping, regardless of the drainage conditions. However, microstructural observations indicate deformation by ductile mechanisms at higher strain under both undrained and drained conditions. The rheology and microstructures suggest dehydrating serpentinite deforms via semibrittle flow with grain-scale ductile deformation more active at high pore fluid pressures. Our results suggest that earthquakes in serpentinized mantle do not nucleate as a direct result of unstable frictional sliding along fractures generated at the onset of dehydration reactions.

  1. Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li+ electrolyte at room temperature as a function of potential in a range of -0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott-Schottky analysis of capacitances extracted from the impedance spectra. Further the ioniom the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35-40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples during hot conditioning.

  2. Evaporation kinetics of oxide fuels and their consequences on actinide redistributions in reactor fuel pins and on fuel vapor pressures under conditions of core disruptive accidents

    International Nuclear Information System (INIS)

    This work deals with the evaporation kinetics of UO2 and (U,Pu)O2. Mathematical models were developed for free evaporation and for evaporation in closed cavities, which allow to calculate location and time dependent redistribution in evaporating specimens. The following two evaporation processes were studied: 1) evaporation of (U,Pu) mixed oxide in fuel pores,which migrate towards the center of the fuel pin and contribute to radial (U,Pu) redistribution; and 2) evaporation of liquid oxide fuels under core disruptive accident conditions in hypothetical prompt critical excursions. The calculations made with respect to core accident conditions have shown that the fuel surface composition changes rapidly in open-evaporation, when the fuel evaporates freely or into major cavities. The changes of surface composition result in a change of the vapor pressure over the oxide. So, the calculated total vapor pressure during free evaporation of (U,Pu)O2 is lower by the factor 2-7 (depending on the evaporation temperature) than the equation-of-state pressure of (U,Pu)O2 with unchanged composition. The changes in surface composition also entail other significant consequences for theoretical and experimental investigations dealing with the high-temperature evaporation of oxide fuels. Calculations on pore migration have shown that a pore migrating as a result of evaporation and condensation of (U,Pu) mixed oxide will transport Pu (or U) to the center of the fuel pin. Starting from this single effect it was calculated the total redistribution effect caused in a fuel pin by migrating pores. It was shown in an out-of-pile experiment that the migration of pores in the temperature gradient is an effective mechanism for (U,Pu) redistribution. This was also confirmed by post-irradiation investigations of pins of an FR2 irradiation experiment. Superposition of the redistribution effect of pore migration on that of thermodiffusion yielded good agreement between measured and calculated radial (U,Pu) distributions for three fuel pins having initial stoichiometries of 1.90, 1.95 and 2.003, respectively. (orig./RW)

  3. Polystyrene as a model system to probe the impact of ambient gas chemistry on polymer surface modifications using remote atmospheric pressure plasma under well-controlled conditions.

    Science.gov (United States)

    Bartis, Elliot A J; Luan, Pingshan; Knoll, Andrew J; Hart, Connor; Seog, Joonil; Oehrlein, Gottlieb S

    2015-01-01

    An atmospheric pressure plasma jet (APPJ) was used to treat polystyrene (PS) films under remote conditions where neither the plume nor visible afterglow interacts with the film surface. Carefully controlled conditions were achieved by mounting the APPJ inside a vacuum chamber interfaced to a UHV surface analysis system. PS was chosen as a model system as it contains neither oxygen nor nitrogen, has been extensively studied, and provides insight into how the aromatic structures widespread in biological systems are modified by atmospheric plasma. These remote treatments cause negligible etching and surface roughening, which is promising for treatment of sensitive materials. The surface chemistry was measured by X-ray photoelectron spectroscopy to evaluate how ambient chemistry, feed gas chemistry, and plasma-ambient interaction impact the formation of specific moieties. A variety of oxidized carbon species and low concentrations of NOx species were measured after APPJ treatment. In the remote conditions used in this work, modifications are not attributed to short-lived species, e.g., O atoms. It was found that O3 does not correlate with modifications, suggesting that other long-lived species such as singlet delta oxygen or NOx are important. Indeed, surface-bound NO3 was observed after treatment, which must originate from gas phase NOx as neither N nor O are found in the pristine film. By varying the ambient and feed gas chemistry to produce O-rich and O-poor conditions, a possible correlation between the oxygen and nitrogen composition was established. When oxygen is present in the feed gas or ambient, high levels of oxidation with low concentrations of NO3 on the surface were observed. For O-poor conditions, NO and NO2 were measured, suggesting that these species contribute to the oxidation process, but are easily oxidized when oxygen is present. That is, surface oxidation limits and competes with surface nitridation. Overall, surface oxidation takes place easily, but nitridation only occurs under specific conditions with the overall nitrogen content never exceeding 3%. Possible mechanisms for these processes are discussed. This work demonstrates the need to control plasma-ambient interactions and indicates a potential to take advantage of plasma-ambient interactions to fine-tune the reactive species output of APP sources, which is required for specialized applications, including polymer surface modifications and plasma medicine. PMID:25930012

  4. Natural convection heat transfer of water on a horizontal downward facing stainless steel disk in a gap under atmospheric pressure conditions

    International Nuclear Information System (INIS)

    An experimental study on natural convection heat transfer on a horizontal downward facing heated surface in a water gap has been carried out under atmospheric pressure conditions. A total of 7204 experimental data points are correlated using Rayleigh versus Nusselt number correlations in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures are discussed. The buoyancy force acts as a resistance force for natural convection heat transfer on a downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of Rayleigh number, or Rayleigh and Prandtl numbers both, may be used. However, the best accuracy is provided by an empirical correlation which expresses the Nusselt number as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature

  5. Modelling the chemical behaviour of tellurium species in the reactor pressure vessel and the reactor cooling system under severe accident conditions

    International Nuclear Information System (INIS)

    This state of the art report contains information on the behaviour of tellurium and its compounds in the reactor pressure vessel and the reactor coolant system under light water reactor severe accident conditions. To characterise tellurium behaviour, it is necessary the previous knowledge of the species of tellurium released from the core, and simultaneity of its release with that of other materials which can alter the transport, for instance, control rod and structural materials. Release and transport experiments have been reviewed along with the models implemented in the codes which are used in the international community: TRAPMELT, RAFT, VICTORIA and SOPHIE. From the experiments, it can be concluded that other species different to Te2, such as tin telluride and cesium telluride, may be released from the fuel. That is why they must be considered in the transport phenomena. There is also experimental evidence of the strong interaction of Te2 with Inconel 600 and stainless steel of the pipe walls and structures, however this strong interaction is in competition with the interaction of tellurium with aerosols, which under severe accident conditions may represent an area greater than that of the primary system. It is for the absence of significant tellurium species in the transport models, and also for the interaction of tellurium with aerosols, for which some codes show the greatest deficiencies

  6. Uniform, stable, and efficient planar-heterojunction perovskite solar cells by facile low-pressure chemical vapor deposition under fully open-air conditions.

    Science.gov (United States)

    Luo, Paifeng; Liu, Zhaofan; Xia, Wei; Yuan, Chenchen; Cheng, Jigui; Lu, Yingwei

    2015-02-01

    Recently, hybrid perovskite solar cells (PSCs) have attracted extensive attention due to their high efficiency and simple preparing process. Herein, a facile low-pressure chemical vapor deposition (LPCVD) technology is first developed to fabricate PSCs, which can effectively reduce the over-rapid intercalating reaction rate and easily overcome this blocking issue during the solution process. As a result, the prepared uniform perovskite films exhibit good crystallization, strong absorption, and long carrier diffusion length. More strikingly, CH3NH3PbI3 absorbers by LPCVD demonstrate excellent moisture-resistant feature even under laser illumination and high-temperature conditions, which indicates that our proprietary method is very suitable for the future low-cost, nonvacuum production of the new generation photovoltaic devices. Finally, high efficiency of 12.73% is successfully achieved under fully open-air conditions. To the best of our knowledge, this is the first report of efficient PSCs with such a high humidity above 60%. PMID:25581720

  7. The influence of radiative heat exchange on the character of gasdynamic flows under conditions of pulsed discharge in high-pressure cesium vapor

    Science.gov (United States)

    Baksht, F. G.; Lapshin, V. F.

    2015-01-01

    The gasdynamics of pulse-periodic radiative discharge in high-pressure cesium vapor has been studied in the framework of a two-temperature multifluid model. It is established that, at a limited volume of the gas-discharge tube, the character of gasdynamic flows depends on the conditions of radiative heat exchange in discharge plasma. In cases in which the main contribution to radiative energy losses is related to a spectral region with optical thickness ? R (?) ˜ 1, there is nonlocal radiative heat exchange in discharge plasma, which is uniformly heated over the entire tube volume and moves from the discharge axis to tube walls during the entire pulse of discharge current. Under the conditions of radiative losses determined by the spectral region where ? R (?) ? 1, the reabsorption of radiation is absent and discharge plasma is nonuniformly heated by the current pulse. This leads to the appearance of reverse motions, so that the heated plasma is partly pushed toward the tube walls and partly returned to the discharge axis.

  8. Steady state and stability characteristics of natural circulation loops operating with carbon dioxide at supercritical pressures for open and closed loop boundary conditions

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Natural circulation experiments conducted with supercritical carbon dioxide. • The instability observed in the pseudo-critical temperature range of operation. • Instability is found for small power range bounded by upper and lower stable zones. • NOLSTA code predicts very large unstable zone compared to experimental data. • Thermal capacitance model included in NOLSTA code to simulate experimental data. - Abstract: Experiments were conducted in a closed supercritical pressure natural circulation loop (SPNCL) with carbon dioxide as working fluid. Instability was observed in a narrow window of power with the loop operating in the pseudo-critical temperature range (heater inlet temperature in the range of 27–31 °C and heater outlet temperature oscillating from 29 to 45 °C). Only horizontal heater horizontal cooler orientation exhibited instability and that too at low secondary side chilled water mass flow rate, i.e. 10–15 lpm. A computer code NOLSTA has been developed to carry out steady state and stability analysis of open and closed loop natural circulation at supercritical conditions. The code adequately predicts steady state natural circulation performance for both open and closed loop boundary conditions. However, code predicts very large unstable zone for SPNCL, hence pipe wall thermal capacitance models were incorporated in NOLSTA code to simulate the experimental results. The stability predictions by NOLSTA code (with pipe wall thermal capacitance model) have been compared with experimental data available in open literature and experiments conducted in SPNCL

  9. Tunnel construction work under high earth pressure and springwater flouing condition. Construction details of a pioneer drift for Hida tunnel, Tokai-Hokuriku expressway

    International Nuclear Information System (INIS)

    Tunnels such as those planned for the International Linear Collider (ILC) Project are long and narrow structures under the ground. In the construction of these tunnels, various circumstances sometimes restrict the initial surveys from obtaining detailed geological information. In Japan, complicated geological structure composed of discontinuous plate tectonics can be found. Therefore, in order to ensure effective construction planning and execution, it is important that precise geological information be acquired through initial survey and then verified with investigation results during the construction. Hida Tunnel of Tokai Hokuriku Expressway, which is 10.7 km long and took more than 11 years to finish, is the second longest highway tunnel in Japan. The tunnel was constructed using the TBM method in the beginning. Later the method was replaced with NATM because of hostile construction conditions, which include existences of springwater and massive earth pressure due to more than 1000 m of earth loading on top, as well as weak zones consisted of active faults. This paper reports on the geological structure and construction details of a pioneer drift for Hida Tunnel, which was completed by overcoming complicated and poor geological conditions. At the same time, we will mention the ideal method of the geological survey in future ILC plan. (author)

  10. Distinguishing HIV-1 drug resistance, accessory, and viral fitness mutations using conditional selection pressure analysis of treated versus untreated patient samples

    Directory of Open Access Journals (Sweden)

    Lee Christopher

    2006-05-01

    Full Text Available Abstract Background HIV can evolve drug resistance rapidly in response to new drug treatments, often through a combination of multiple mutations 123. It would be useful to develop automated analyses of HIV sequence polymorphism that are able to predict drug resistance mutations, and to distinguish different types of functional roles among such mutations, for example, those that directly cause drug resistance, versus those that play an accessory role. Detecting functional interactions between mutations is essential for this classification. We have adapted a well-known measure of evolutionary selection pressure (Ka/Ks and developed a conditional Ka/Ks approach to detect important interactions. Results We have applied this analysis to four independent HIV protease sequencing datasets: 50,000 clinical samples sequenced by Specialty Laboratories, Inc.; 1800 samples from patients treated with protease inhibitors; 2600 samples from untreated patients; 400 samples from untreated African patients. We have identified 428 mutation interactions in Specialty dataset with statistical significance and we were able to distinguish primary vs. accessory mutations for many well-studied examples. Amino acid interactions identified by conditional Ka/Ks matched 80 of 92 pair wise interactions found by a completely independent study of HIV protease (p-value for this match is significant: 10-70. Furthermore, Ka/Ks selection pressure results were highly reproducible among these independent datasets, both qualitatively and quantitatively, suggesting that they are detecting real drug-resistance and viral fitness mutations in the wild HIV-1 population. Conclusion Conditional Ka/Ks analysis can detect mutation interactions and distinguish primary vs. accessory mutations in HIV-1. Ka/Ks analysis of treated vs. untreated patient data can distinguish drug-resistance vs. viral fitness mutations. Verification of these results would require longitudinal studies. The result provides a valuable resource for AIDS research and will be available for open access upon publication at http://www.bioinformatics.ucla.edu/HIV Reviewers This article was reviewed by Wen-Hsiung Li (nominated by Eugene V. Koonin, Robert Shafer (nominated by Eugene V. Koonin, and Shamil Sunyaev.

  11. An application of liquid sublayer dryout mechanism to the prediction of critical heat flux under low pressure and low velocity conditions in round tubes

    International Nuclear Information System (INIS)

    Based on several experimental evidences for nucleate boiling in annular film and the existence of residual liquid film flow rate at the critical heat flux (CHF) location, the liquid sublayer dryout (LSD) mechanism under annular film is firstly introduced to evaluate the CHF data at low pressure and low velocity (LPLV) conditions, which would not be predicted by a normal annular film dryout (AFD) model. In this study, the CHF occurrence due to annular film separation or breaking down is phenomenologically modelled by applying the LSD mechanism to this situation. In this LSD mechanism, the liquid sublayer thickness, the incoming liquid velocity to the liquid sublayer, and the axial distance from the onset of annular flow to the CHF location are used as the phenomena-controlling parameters. From the model validation on the 1406 CHF data points ranging over P = 0.1 - 2 MPa, G = 4 - 499 kg/m2s, L/D = 4 - 402, most of CHF data (more than 1000 points) are predicted within ±30% error bounds by the LSD mechanism. However, some calculation results that critical qualities are less than 0.4 are considerably overestimated by this mechanism. These overpredictions seem to be caused by inadequate CHF mechanism classification criteria and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities and a new bubble detachment model for LPLV conditions are neededment model for LPLV conditions are needed to improve the model accuracy. (author)

  12. Breeding pond selection and movement patterns by eastern spadefoot toads (Scaphiopus holbrookii) in relation to weather and edaphic conditions.

    Energy Technology Data Exchange (ETDEWEB)

    Greenberg, Cathyrn, H.; Tanner, George, W.

    2004-08-31

    Cathryn H. Greenberg and George W. Tanner. 2004. Breeding pond selection and movement patterns by eastern spadefoot toads (Scaphiopus holbrookii) in relation to weather and edaphic conditions. J. Herp. 38(4):569-577. Abstract: Eastern Spadefoot Toads (Scaphiopus holbrookii) require fish-free, isolated, ephemeral ponds for breeding but otherwise inhabit the surrounding uplands, commonly xeric longleaf pine (Pinus palustris) ?wiregrass (Aristida beyrichiana). Hence both pond and upland conditions can potentially affect their breeding biology, and population persistence. Hardwood invasion due to fire suppression in sandhills could alter upland and pond suitability by higher hardwood density and increased transpiration. In this paper we explore breeding and neonatal emigration movements in relation to weather, hydrological conditions of ponds, and surrounding upland matrices. We use 9 years of data from continuous monitoring with drift fences and pitfall traps at 8 ephemeral ponds in 2 upland matrices: regularly-burned, savanna-like sandhills (n = 4), and hardwood-invaded sandhills (n = 4). Neither adult nor neonate captures differed between ponds within the 2 upland matrices, suggesting that they are tolerant of upland heterogeneity created by fire frequency. Explosive breeding occurred during 9 periods and in all seasons; adults were captured rarely otherwise. At a landscape-level rainfall, maximum change in barometric pressure, and an interaction between those 2 variables were significant predictors of explosive breeding. At a pond-level, rainfall, change in pond depth during the month prior to breeding, and days since a pond was last dry were significant predictors of adult captures. Transformation date, rather than weather, was associated with neonatal emigrations, which usually were complete within a week. Movement by first-captured adults and neonates was directional, but adult emigrations were apparently not always toward their origin. Our results suggest that Spadefoot Toads are highly adapted to breeding conditions and upland habitat heterogeneity created by weather patterns and fire frequency in Florida sandhills.

  13. Restriction of transpiration rate under high vapour pressure deficit and non-limiting water conditions is important for terminal drought tolerance in cowpea.

    Science.gov (United States)

    Belko, N; Zaman-Allah, M; Diop, N N; Cisse, N; Zombre, G; Ehlers, J D; Vadez, V

    2013-03-01

    Drought stress is a major constraint on cowpea productivity, since the crop is grown under warm conditions on sandy soils having low water-holding capacity. For enhanced performance of crops facing terminal drought stress, like cowpea, water-saving strategies are crucial. In this work, the growth and transpiration rate (TR) of 40 cowpea genotypes with contrasting response to terminal drought were measured under well-watered conditions across different vapour pressure deficits (VPD) to investigate whether tolerant and sensitive genotypes differ in their control of leaf water loss. A method is presented to indirectly assess TR through canopy temperature (CT) and the index of canopy conductance (Ig). Overall, plants developed larger leaf area under low than under high VPD, and there was a consistent trend of lower plant biomass in tolerant genotypes. Substantial differences were recorded among genotypes in TR response to VPD, with tolerant genotypes having significantly lower TR than sensitive ones, especially at times with the highest VPD. Genotypes differed in TR response to increasing VPD, with some tolerant genotypes exhibiting a clear VPD breakpoint at about 2.25?kPa, above which there was very little increase in TR. In contrast, sensitive genotypes presented a linear increase in TR as VPD increased, and the same pattern was found in some tolerant lines, but with a smaller slope. CT, estimated with thermal imagery, correlated well with TR and Ig and could therefore be used as proxy for TR. These results indicate that control of water loss discriminated between tolerant and sensitive genotypes and may, therefore, be a reliable indicator of terminal drought stress tolerance. The water-saving characteristics of some genotypes are hypothesised to leave more soil water for pod filling, which is crucial for terminal drought adaptation. PMID:22823007

  14. An utilization of liquid sublayer dryout mechanism in predicting critical heat flux under low pressure and low velocity conditions in round tubes

    International Nuclear Information System (INIS)

    From a theoretical assessment of extensive critical heat flux (CHF) data under low pressure and low velocity (LPLV) conditions, it was found out that lots of CHF data would not be well predicted by a normal annular film dryout (AFD) mechanism, although their flow patterns were identified as annular-mist flow. To predict these CHF data, a liquid sublayer dryout (LSD) mechanism has been newly utilized in developing the mechanistic CHF model based on each identified CHF mechanism. This mechanism postulates that the CHF occurrence is caused by dryout of the thin liquid sublayer resulting from the annular film separation or breaking down due to nucleate boiling in annular film or hydrodynamic fluctuation. In principle, this mechanism well supports the experimental evidence of residual film flow rate at the CHF location, which can not be explained by the AFD mechanism. For a comparative assessment of each mechanism, the CHF model based on the LSD mechanism is developed together with that based on the AFD mechanism. The validation of these models is performed on the 1406 CHF data points ranging over P=0.1-2 MPa, G=4-499 kg m-2 s-1, L/D=4-402. This model validation shows that 1055 and 231 CHF data are predicted within ±30 error bound by the LSD mechanism and the AFD mechanism, respectively. However, some CHF data whose critical qualities are <0.4 or whose tube length-to-diameter ratios are <70 are considerably overestimated by the CHF model based on theerestimated by the CHF model based on the LSD mechanism. These overestimations seem to be caused by an inadequate CHF mechanism classification and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities as well as a new bubble detachment model for LPLV conditions, are needed to improve the model accuracy.

  15. Territorial characterisation considering geo morphological properties of subsoil as well as climatic and meteorological conditions for the evaluation of the effects of radiological nature on the environment

    International Nuclear Information System (INIS)

    The composition and origin of the rocky substratum, the permeability of the ground, its degree of humidity and the particle size are the main factors that influence radon concentration in the subsoil and in the water stratums as well as its upward migration. The climatic and meteorological conditions, particularly the moisture, the barometric pressure and the temperature, can influence more or less directly the underground emanation and diffusion properties of radon and thoron giving rise to short-term modifications of radiological nature in the subsoil, closely related to the presence of these elements. The great concentration of some radioisotopes, in some particular areas, can also induce high dose rates caused by the radiation coming from emergent rocks, due for instance to activities related to building works, with consequent possible exposure of the personnel involved in underground excavations. In such situations it is possible to carry out systematical radiometric measurements, which provide instantaneous and time integrated data, using fixed or movable instrumentation. The stratigraphical structure of the subsoil and the related variations of lithological nature as well as the lack of homogeneity in the land, due also to the unevenness of the ground outline and to the presence of fault planes, increase considerably the complexity of analytical evaluations based upon the chemical and physical characteristics of the subsoil and upon the meteorological and climatic properties

  16. Estimating the angle of attack from blade pressure measurements on the NREL Phase VI rotor using a free wake vortex model: axial conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sant, Tonio [Delft Univ. of Technology, Faculty of Aerospace Engineering, Delft (Netherlands); Malta Univ., Mechanical Engineering Dept., Msida (Malta); Kuik, Gijs van; Bussel, G.J.W. van [Delft Univ. of Technology, Faculty of Aerospace Engineering, Delft (Netherlands)

    2006-07-01

    Blade element momentum (BEM) methods are still the most common methods used for predicting the aerodynamic loads during the aeroelastic design of wind turbine blades. However, their accuracy is limited by the availability of reliable aerofoil data. Owing to the 3D nature of the flow over wind turbine blades, the aerofoil characteristics will vary considerably from the 2D aerofoil characteristics, especially at the inboard sections of the blades. Detailed surface pressure measurements on the blade surfaces may be used to derive more realistic aerofoil data. However, in doing so, knowledge of the angle of attack distributions is required. This study presents a method in which a free wake vortex model is used to derive such distributions for the NREL Phase VI wind turbine under different operating conditions. The derived free wake geometry solutions are plotted together with the corresponding wake circulation distribution. These plots provide better insight into how circulation formed at the blades is eventually diffused into the wake. The free wake model is described and its numerical behaviour is examined. (Author)

  17. Photoluminescence properties of ?-Ca3(PO4)2:Sm3+ prepared under high-pressure and high-temperature conditions

    Science.gov (United States)

    Xue, Weihong; Zhai, Shuangmeng; Xu, Shiqing

    2015-07-01

    ?-Ca3(PO4)2:Sm3+ samples were synthesized under high-pressure and high-temperature conditions. The samples were characterized by X-ray diffraction measurements. The excitation and emission spectra and fluorescence decay curves of synthesized samples were collected to study the photoluminescence properties. The excitation spectra of ?-Ca3(PO4)2:Sm3+ exhibit a series of narrow peaks attributed to the typical f-f transition of Sm3+. The emission spectra of ?-Ca3(PO4)2:Sm3+ compose of four bands attributed to transitions from 4G5/2 excited state to 6HJ/2 (J = 5, 7, 9 and 11) ground states of Sm3+. The average decay lifetimes were obtained by fitting the decay curves for 6H7/2 level of Sm3+ emission using a double exponential function. The photoluminescent spectra of ?-Ca3(PO4)2:Sm3+ show that the samples belong to a red-emitting phosphor and can be pumped in the near ultraviolet light region, which can easily be applied for NUV LED chips and thus in WLEDs. There exists a concentration quenching of Sm3+ in ?-Ca3(PO4)2:Sm3+ samples. The critical concentration of Sm3+ in ?-Ca3(PO4)2 is about 1.0 mol%.

  18. Critical heat flux enhancement in flow boiling of Al2O3 and SiC nanofluids under low pressure and low flow conditions

    International Nuclear Information System (INIS)

    Critical heat flux (CHF) is the thermal limit of a phenomenon in which a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the heat transfer efficiency, thus causing localized overheating of the heating surface. The enhancement of CHF can increase the safety margins and allow operation at higher heat fluxes; thus, it can increase the economy. A very interesting characteristic of nanofluids is their ability to significantly enhance the CHF. Nanofluids are nanotechnology-based colloidal dispersions engineered through the stable suspension of nanoparticles. All experiments were performed in round tubes with an inner diameter of 0.01041 m and a length of 0.5 m under low pressure and low flow (LPLF) conditions at a fixed inlet temperature using water, 0.01 vol.% Al2O3/water nanofluid, and SiC/water nanofluid. It was found that the CHF of the nanofluids was enhanced and the CHF of the SiC/water nanofluid was more enhanced than that of the Al2O3/water nanofluid.

  19. Study on critical heat flux enhancement in flow boiling of SiC nano-fluids under low pressure and low flow conditions

    International Nuclear Information System (INIS)

    Critical heat flux (CHF) is the thermal limit of a phenomenon in which a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the heat transfer efficiency, thus causing localized overheating of the heating surface. The enhancement of CHF can increase the safety margins and allow operation at higher heat fluxes; thus, it can increase the economy. A very interesting characteristics of nano-fluids is their ability to significantly enhance the CHF. nano-fluids are nano-technology-based colloidal dispersions engineered through stable suspending of nanoparticles. All experiments were performed in round tubes with an inner diameter of 0.01041 m and a length of 0.5 m under low pressure and low flow (LPLF) conditions at a fixed inlet temperature using water, 0.01 vol. % Al2O3/water and SiC/water nano-fluids. It was found that the CHF of the nano-fluids was enhanced and the CHF of the SiC/water nano-fluid was more enhanced than that of the Al2O3/water nano-fluid. (authors)

  20. Infrared laser-induced post-pulse dissociation of CF2HCl and CF2Cl2 under high pressure and fluence conditions

    Science.gov (United States)

    Strube, W.; Wollbrandt, J.; Rossberg, M.; Linke, E.

    1996-12-01

    The unimolecular decomposition of the halogenated methanes CF2HCl (one main channel) and CF2Cl2 (two main channels) in the focused beam of a pulsed CO2 laser under high pressure and fluence conditions (p=100 Pa-2 kPa; ?=5-200 J/cm2) was studied by a special laser-induced fluorescence (LIF) technique, permitting spatially resolved fragment concentration measurements in the focal region. Considerable amounts of CF2 product were formed after the end of the laser pulse. In the one-channel-dissociation case of CF2HCl LIF measurements of the CF2 yield distribution Y(z,r) can be related to the spatial distribution of the average absorbed energy in the parent molecules. Only part of the absorbed energy is consumed by multiphoton dissociation, while most reactant molecules remain highly vibrationally excited in the focus volume far into the double cone. Using the long-lived CF2 also as a probe for measuring the rotational, translational, and vibrational temperatures, the redistribution of the internal energy in the molecules and fragments involved is monitored. The post-pulse production of CF2 is shown to be caused by the energy pooling v-v transfer mechanism, while contributions of pyrolytic and gas dynamic processes are of little importance.

  1. An experimental study on the critical heat flux for low flow of water in a non-uniformly heated vertical rod bundle over a wide range of pressure conditions

    International Nuclear Information System (INIS)

    An experimental study of the critical heat flux (CHF) has been performed for a water flow in a non-uniformly heated vertical 3 x 3 rod bundle under low flow and a wide range of pressure conditions. The experiment was especially focused on the parametric trends of the CHF and the applicability of the conventional CHF correlations to a return-to-power conditions of a main steam line break accident whose conditions might be a low mass flux, intermediate pressure, and a high inlet subcooling. The effects of the mass flux and pressure on the CHF are relatively large and complicated in the low pressure conditions. At a high mass flux or a low critical quality, the local heat flux at the CHF location sharply decreases with an increasing local critical quality. However, at a low mass flux or a high critical quality, the local heat flux at the CHF location shows a nearly constant value regardless of the increase of the critical quality. The CHF data at the very low mass flux conditions are correlated well by the churn-to-annular flow transition criterion or the flow reversal phenomena. Several conventional CHF correlations predict the present return-to-power CHF data with reasonable accuracies. However, the prediction capabilities become worse in a very low mass flux of below about 100 kg/(m2 s)

  2. Transition pressures and enthalpy barriers for the cd->beta-tin transition in Si and Ge under non-hydrostatic conditions

    OpenAIRE

    Gaal-nagy, Katalin; Strauch, Dieter

    2005-01-01

    We present an ab-initio study of the phase transition cd->beta-tin in Si and Ge under hydrostatic and non-hydrostatic pressure. For this purpose we have developed a new method to calculate the influence of non-hydrostatic pressure components not only on the transition pressure but also on the enthalpy barriers between the phases. We find good agreement with available experimental and other theoretical data. The calculations have been performed using the plane-wave pseudopote...

  3. Effect of chloride transients on the corrosion behavior of low-alloy steels in cladding flaws of reactor pressure vessels under oxygenated high-temperature water conditions

    International Nuclear Information System (INIS)

    Strain-induced corrosion cracking in low alloy steels (LAS) has been extensively investigated during the last decades. One finding from recent investigations is the detrimental role of even small amounts of chlorides, which has been shown to increase the cracking susceptibility of LAS. In order to evaluate this finding a demanding research programme has been established. In light water reactor plants, the pressure vessel and in some cases also the piping is made of LAS, covered with welded stainless steel cladding for improved corrosion protection. In structural failure assessments of primary circuits, penetrating cladding flaws have to be assumed, which could locally expose the underlying LAS to the cooling water. Due to the narrow opening of such weld defects the aqueous solution in contact with the underlying LAS would have a different composition from that of the bulk cooling water. In this paper, first detailed calculations of the water chemistry prevailing in such conditions revealed that oxygen concentration decreases rapidly when going from the mouth of the cladding flaw towards the bottom, bringing the redox potential to values, much lower than those typical for oxygenated high temperature water (HTW). Also, chloride was found to enrich into the cladding flaw volume by a factor of x30. The material studied was 20MnMoNi55 used for the reactor coolant line of a German NPP. Based on the results obtained, it can be concluded that chloride transients up to 50 ppb in the bulk HTW, resulting in an enrichment of chloride in a penetrating cladding flaw up to 1,500 ppb, do not result in any serious consequences for the corrosion of LAS at the bottom of the cladding flaw. (orig.)

  4. Effect of chloride transients on the corrosion behavior of low-alloy steels in cladding flaws of reactor pressure vessels under oxygenated high-temperature water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bojinov, Martin [University of Chemical Technology and Metallurgy, Sofia (Bulgaria). Dept. of Physical Chemistry; Nowak, Erika; Stanislowski, Michael [E.ON Kernkraft GmbH, Hannover (Germany); Saario, Timo [VTT Technical Research Centre of Finland, Espoo (Finland). VTT Materials and Building

    2014-04-15

    Strain-induced corrosion cracking in low alloy steels (LAS) has been extensively investigated during the last decades. One finding from recent investigations is the detrimental role of even small amounts of chlorides, which has been shown to increase the cracking susceptibility of LAS. In order to evaluate this finding a demanding research programme has been established. In light water reactor plants, the pressure vessel and in some cases also the piping is made of LAS, covered with welded stainless steel cladding for improved corrosion protection. In structural failure assessments of primary circuits, penetrating cladding flaws have to be assumed, which could locally expose the underlying LAS to the cooling water. Due to the narrow opening of such weld defects the aqueous solution in contact with the underlying LAS would have a different composition from that of the bulk cooling water. In this paper, first detailed calculations of the water chemistry prevailing in such conditions revealed that oxygen concentration decreases rapidly when going from the mouth of the cladding flaw towards the bottom, bringing the redox potential to values, much lower than those typical for oxygenated high temperature water (HTW). Also, chloride was found to enrich into the cladding flaw volume by a factor of x30. The material studied was 20MnMoNi55 used for the reactor coolant line of a German NPP. Based on the results obtained, it can be concluded that chloride transients up to 50 ppb in the bulk HTW, resulting in an enrichment of chloride in a penetrating cladding flaw up to 1,500 ppb, do not result in any serious consequences for the corrosion of LAS at the bottom of the cladding flaw. (orig.)

  5. Pulse radiolysis study on temperature and pressure dependence of the yield of solvated electron in methanol from room temperature to supercritical conditionPulse radiolysis study on temperature and pressure dependence of the yield of solvated electron in methanol from room temperature to supercritical condition

    International Nuclear Information System (INIS)

    A new concept of nuclear reactor, supercritical water-cooled reactor (SCWR), has been proposed, which is based on the success of the use of supercritical water (SCW) in fossil fuel power plants for more than three decades. This new concept reactor has advantages of higher thermal conversion efficiency, simplicity in structure, safety, etc, and it has been selected as one of the reactor concepts for the next generation nuclear reactor systems. In these reactors, the same as in boiling water reactors (BWR) and pressurized water reactors (PWR), water is used not only as a coolant but also as a moderator. It is very important to understand the behavior of the radiolysis products of water under the supercritical condition, since the water is exposed to a strong radiation field under very high temperature condition. Usually, in order to predict the concentrations of water decomposition products with carrying out some kinds of computer simulations, knowledge of the temperature and/or pressure dependent G-values (denoting the experimentally measured radiolytic yields) as well as of the rate constants of a set of reactions becomes very important. Therefore, in recent years, two groups from Argonne National Laboratory and The University of Tokyo, simultaneously conducted two projects aimed at obtaining basic data on radiolysis of SCW. However, it is still lack of reliable radiolytic yields of water decomposition products in very high temperature region. As we known, the properties of solvated electrons in polar liquid are very helpful for our understanding how they play a central role in many processes, such as solvation and reducing reactions. The solvated electron can also be used as a probe to determine the dynamic nature of the polar liquid systems. Comparing to water, the primary alcohols have much milder critical points, for example, for water and methanol, the critical temperature and pressure are 374 deg. C and 22.1 MPa and 239.5 deg. C and 8.1 MPa, respectively. Therefore, it was suggested that the supercritical primary alcohols, for example methanol, as the simplest alcohol and an analogue of water, might become a promising substitute of water in a radiolysis study. As our knowledge, the yield of solvated electron in methanol at high temperatures and pressures, especially at supercritical condition, is still unknown now. In this work, the yield of solvated electron in methanol has been investigated at different temperatures from room temperature to supercritical condition by a method of nanosecond pulse radiolysis. By using 4,4'-bipyridyl as a scavenger, the temperature-, pressure- and density-dependent yields of solvated electron, i.e., G-values, have been measured for the first time, which revealing a special density effect on the yield in supercritical methanol. With increasing temperature under 9 MPa, the yield just changes slightly below 230 deg. C, and increases dramatically to peak at around 250 deg. C, after that decreases again. The pressure and density dependence of the yields at elevated temperatures are also measured and discussed. The results imply that, in supercritical region, especially near to critical point, the density effect becomes predominant influence on the yield of radiolysis products. (authors)A new concept of nuclear reactor, supercritical water-cooled reactor (SCWR), has been proposed, which is based on the success of the use of supercritical water (SCW) in fossil fuel power plants for more than three decades. This new concept reactor has advantages of higher thermal conversion efficiency, simplicity in structure, safety, etc, and it has been selected as one of the reactor concepts for the next generation nuclear reactor systems. In these reactors, the same as in boiling water reactors (BWR) and pressurized water reactors (PWR), water is used not only as a coolant but also as a moderator. It is very important to understand the behavior of the radiolysis products of water under the supercritical condition, since the water is exposed to a strong radiation field under very high temperature c

  6. Biogas barometer; Le barometre biogaz

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-12-15

    This annual evaluation is a synthesis of works published in 2006. Comparisons are presented between the wind power performances and European Commission White Paper and Biomass action plan objectives. The United Kingdom is the leading european country in terms of production, but is being challenged more and more by Germany, which markedly increased its production in 2005. France is only classed 5. in Europe in spite of a valorisable potential. (A.L.B.)

  7. Þeistareykir high-temperature geothermal field, North-East Iceland : estimation of reservoir conditions and evaluation of pressure interference between wells

    OpenAIRE

    Júlía Úlfdís Jóhannsson

    2010-01-01

    The Þeistareykir high-temperature geothermal field is located in northern Iceland. Seven deep boreholes have been drilled there since 2002. Temperature and pressure logs, measured during different operational stages of the wells, were analyzed to estimate formation temperature and initial pressure, as well as the possible location of feed zones in the wells. A new interpretation supports the hypothesis of an up-flow around well ÞG-1. It is possible that the up-flow does not spr...

  8. Test report: Preliminary tests for the High Flux Reactor: Experimental determination of flow redistribution conditions at pressures between 4 and 5 kg/cm2 abs in a rectangular channel 2 mm thick and 60 cm long

    International Nuclear Information System (INIS)

    In the context of safety research for the OSIRIS reactor, tests have been performed on the Super BOB cell with a view to determining experimentally the internal characteristics (or ''S'' curves) of a channel with a rectangular heating cross-section 2 x 38 mm and 600 mm long. During these tests the maximum pressure at the channel exit was brought to 3 kg/cm2 abs. The pressurization level in the High Flux Reactor will be higher. That is why tests have been carried out at maximum pressure of 5 kg/cm2 abs allowable on the ''super BOB'' loop without modifying it. The first objective of this test series was to determine the ''S'' curves and the exchange coefficients experimentally. This document discusses the test conditions and test results

  9. Effect of amiloride and spironolactone on renal tubular function and central blood pressure in patients with arterial hypertension during baseline conditions and after furosemide: a double-blinded, randomized, placebo-controlled crossover trial.

    Science.gov (United States)

    Matthesen, Solveig K; Larsen, Thomas; Vase, Henrik; Lauridsen, Thomas G; Jensen, Janni M; Pedersen, Erling B

    2013-01-01

    This study demonstrates that the increased potassium content in the body seems to change both the blood pressure and renal tubular function. We wanted to test the hypotheses that amiloride and spironolactone induced potassium retention reduces ambulatory blood pressure (ABP) and central blood pressure (CBP) during baseline conditions and after furosemide and that the tubular transport via the epithelial sodium channels (ENaCs) and aquaporin-2 (AQP2) water channels was increased by furosemide in arterial hypertension. Each of three 28-day treatment periods (placebo, amiloride, and spironolactone) was completed by a 4-day period with standardized diet regarding calories and sodium and water intake. At the end of each period, we measured pulse wave velocity (PWV), central systolic blood pressure (CSBP), central diastolic blood pressure (CDBP), glomerular filtration rate (GFR), free water clearance (CH2O), fractional excretion of sodium (FENa) and potassium (FEK), urinary excretion of AQP2 (u-AQP2), urinary excretion of ?-fraction of the ENaC (u-ENaC?), and plasma concentrations of renin (PRC), angiotensin II (p-Ang II), and aldosterone (p-Aldo) at baseline conditions and after furosemide bolus. Ambulatory blood pressure and CBP were significantly lowered by amiloride and spironolactone. During 24-hour urine collection and at baseline, GFR, CH2O, FENa, FEK, u-AQP2 and u-ENaC? were the same. After furosemide, CH2O, FENa, FEK, u-AQP2, u-ENaC?, PRC, p-Ang II, p-Aldo, PWV and CDBP increased after all treatments. However, during amiloride treatment, FEK increased to a larger extent than after spironolactone and during placebo after furosemide, and CSBP was not significantly reduced. The increases in water and sodium absorption via AQP2 and ENaC after furosemide most likely are compensatory phenomena to antagonize water and sodium depletion. Amiloride is less effective than spironolactone to reduce renal potassium excretion. PMID:22966789

  10. Analysis report of the thermal-hydraulic characteristics of the high temperature/high pressure thermal-hydraulic test facility (VISTA) in steady state conditions

    International Nuclear Information System (INIS)

    The VISTA (Experimental Verification by Integral Simulation of Transients and Accidents) is an experimental facility to verify the performance and safety issues of the SMART-P (Pilot plant of the system-integrated modular advanced reactor). The basic design of the SMART-P has been completed by KAERI. The present report describes the experimental results on the water inventory distribution, the pressure distribution, and the differential pressure characteristics of the VISTA facility and on the heat transfer characteristics of the core simulating heater and the steam generator of the VISTA facility. There were little differences of their water inventories between the designed and the measured data. The pressure of the VISTA primary system kept near the steady-state operating pressure of 147 bar, and the differential pressures through the primary and secondary systems increased with the increase of their flow rates. Also the surface temperatures of core simulating heaters were measured, and the overall heat transfer coefficient of the VISTA steam generator was calculated to show a little higher values than that of the SMART-P

  11. Electrical resistivity of YbRh2Si2 and EuT2Ge2 (T=Co,Cu) at extreme conditions of pressure and temperature

    International Nuclear Information System (INIS)

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical-resistivity measurements, ?(T), from room temperature down to 100 mK. (orig.)

  12. Volume-translated cubic EoS and PC-SAFT density models and a free volume-based viscosity model for hydrocarbons at extreme temperature and pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Ward A; Tapriyal, Deepak; Morreale, Bryan D; Soong, Yee; Baled, Hseen; O Enick, Robert M; Wu, Yue; Bamgbade, Babatunde A; McHugh, Mark A

    2013-12-15

    This research focuses on providing the petroleum reservoir engineering community with robust models of hydrocarbon density and viscosity at the extreme temperature and pressure conditions (up to 533 K and 276 MPa, respectively) characteristic of ultra-deep reservoirs, such as those associated with the deepwater wells in the Gulf of Mexico. Our strategy is to base the volume-translated (VT) Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) cubic equations of state (EoSs) and perturbed-chain, statistical associating fluid theory (PC-SAFT) on an extensive data base of high temperature (278–533 K), high pressure (6.9–276 MPa) density rather than fitting the models to low pressure saturated liquid density data. This high-temperature, high-pressure (HTHP) data base consists of literature data for hydrocarbons ranging from methane to C{sub 40}. The three new models developed in this work, HTHP VT-PR EoS, HTHP VT-SRK EoS, and hybrid PC-SAFT, yield mean absolute percent deviation values (MAPD) for HTHP hydrocarbon density of ?2.0%, ?1.5%, and <1.0%, respectively. An effort was also made to provide accurate hydrocarbon viscosity models based on literature data. Viscosity values are estimated with the frictional theory (f-theory) and free volume (FV) theory of viscosity. The best results were obtained when the PC-SAFT equation was used to obtain both the attractive and repulsive pressure inputs to f-theory, and the density input to FV theory. Both viscosity models provide accurate results at pressures to 100 MPa but experimental and model results can deviate by more than 25% at pressures above 200 MPa.

  13. 1/5-scale experiment of a Mark I boiling-water reactor pressure-suppression system under hypothetical LOCA conditions

    International Nuclear Information System (INIS)

    Experimental results show the sensitivity of hydrodynamically generated vertical loads to changes in the drywell pressurization rate, downcomer submergence, and vent-line loss coefficient. Insignificant effects on peak vertical loads were observed when the vent-line loss was varied. Peak vertical loads can be reduced by adding initial drywell overpressure so that the downcomers are partly cleared of water. Spatial variation of pressure at about the time of vent clearing is seen in comparisons of data from locations along the axis of the toroidal wetwell

  14. In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: A new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions

    Science.gov (United States)

    Lu, W.J.; Chou, I.-Ming; Burruss, R.C.; Yang, M.Z.

    2006-01-01

    A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition. ?? 2006 Society for Applied Spectroscopy.

  15. Assessment of gas production and pressure conditions of fibre reinforced concrete containers under disposal due to microbial degradation and radiolysis of cellulose. The mathematical model

    International Nuclear Information System (INIS)

    The objective of this work was to develop a mathematical model for evaluation of rate of formation of gaseous products of radiolytic and microbial decomposition of cellulose and pressure dependence in fibre reinforced concrete containers contained radioactive wastes at their long-time disposal. (authors)

  16. The Effect of Sliding Speed on Film Thickness and Pressure Supporting Ability of a Point Contact Under Zero Entrainment Velocity Conditions

    Science.gov (United States)

    Thompson, Peter M.; Jones, William R., Jr.; Jansen, Mark J.; Prahl, Joseph M.

    2000-01-01

    A unique tribometer is used to study film forming and pressure supporting abilities of point contacts at zero entrainment velocity (ZEV). Film thickness is determined using a capacitance technique, verified through comparisons of experimental results and theoretical elastohydrodynamic lubrication (EHL) predictions for rolling contacts. Experiments are conducted using through hardened AISI 52 100 steel balls, Polyalphaolefin (PAO) 182 and Pentaerythritol Tetraheptanoate (PT) lubricants, and sliding speeds between 2.0 to 12.0 m/s. PAO 182 and PT are found to support pressures up to 1. 1 GPa and 0.67 GPa respectively. Protective lubricant films ranging in thickness between 90 to 2 10 nm for PAO 182 and 220 to 340 nm for PT are formed. Lubricants experience shear stresses between 14 to 22 MPa for PAO 182 and 7 to 16 MPa for PT at shear rates of 10(exp 7)/sec. The lubricant's pressure supporting ability most likely results from the combination of immobile films and its transition to a glassy solid at high pressures.

  17. Experience of HP 'Termoelektro' in production of universal program for overhaul and following the condition of high pressure steam pipes, with special turn on TPP 'Oslomej' Kichevo - Macedonia

    International Nuclear Information System (INIS)

    In this paper an universal programme for revitalization of the high pressure steam lines in power plants is developed. All this aimed toward providing maximal working cycle continuation as well as better reliability and safety in the exploitation regime. In addition a special turn on the overhaul of the main steam lines and feedwater pipeline at Thermal Power Plant 'Oslomej' (Macedonia) is presented

  18. Experimental study of a low-pressure glow discharge in air in large-diameter discharge tubes: I. Conditions for the normal regime of a glow discharge

    International Nuclear Information System (INIS)

    The initiation and characteristics of a low-pressure glow discharge in air in large-diameter discharge tubes are studied. A deviation from the Paschen law is observed: the breakdown curves Udc(pL) shift toward the higher values of Udc and pL as the interelectrode distance L increases. It is shown that the normal regime of a glow discharge is accompanied by gas ionization in the anode sheath. This takes place only for pL values lying to the right of the inflection point in the breakdown curve. The cathode-sheath characteristics in the normal and abnormal regimes of an air discharge for a duralumin cathode are determined. The axial profiles of the ion density, electron temperature, and plasma potential, as well as the anode voltage drop, are measured at various air pressures

  19. Study of Behavior of Sesame (Sesamum Indicum L.) to Relative Turgidity, Diffusion Pressure Deficit and Transpiration Intensity under Arid Conditions of Western Rajasthan

    OpenAIRE

    Pankaj Swami; Shamindra Saxena; Suman Lata Tripathi

    2010-01-01

    A field experiment was conducted during kharif season of 2008 and 2009 (from august to october) to investigatethe behavior of crop plant Sesame (Sesamum indicum L.) to RT (Relative turgidity), DPD (Diffusion pressuredeficit) and TI (Transpiration intensity). The plant species (Sesamum indicum L.) investigated has been found tobehave differentially with respect to relative turgidity, Diffusion pressure deficit and Transpiration intensityduring different hours of day and at different stages Viz...

  20. Accurate procedure for calculation of compressible fluid pressure drops in isothermal conditions of widely varying pressures like of which are encountered at discharge of safety relief valves, vent and flare headers

    International Nuclear Information System (INIS)

    Heavy Water Plant, Kota employs H2S - H2O exchange for extraction of deuterium from natural water. There is an operating inventory of 160 MT of H2S gas distributed in ten exchange towers. For reasons of safety all possible release routes of H2S gas have been piped to closed vent systems leading to tall flares of 18 inches dia for low releases and 26 inches dia for sudden tower dumping requirements. It was subsequently realised that only one flare of bigger diameter can handle all the loads, and this has become the standard operating practice. While the subject of suitability of smaller flare for dumping loads has been covered in a separate report, a need was felt to have accurate procedures for estimation of gas pressure drops in vent and flare headers. Such piping configurations are common in chemical plants and this problem has been addressed in chemical engineering literature by giving nomograms. However this paper gives an accurate method based on solution of differential equations starting from open end of flare. At open end the pressure is atmospheric. It was used by writing a simple computer program. It is recommended to use this method for sizing of vent and flare headers

  1. Battling High Blood Pressure

    Medline Plus

    Full Text Available ... blood pressure increases your risk for heart attack, stroke and other dangerous conditions. Now, the latest statistics ... with any mention of hypertension were heart disease, stroke, cancer and diabetes…. About 70 million American adults ...

  2. Battling High Blood Pressure

    Medline Plus

    Full Text Available ... Transcript High blood pressure increases your risk for heart attack, stroke and other dangerous conditions. Now, the ... of death with any mention of hypertension were heart disease, stroke, cancer and diabetes…. About 70 million ...

  3. Phase relations in the system KAlSi 3O 8-NaAlSi 3O 8 at high pressure-high temperature conditions and their implication for the petrogenesis of lingunite

    Science.gov (United States)

    Liu, Xi

    2006-06-01

    Multi-anvil experiments have been made with the composition (K 0.2Na 0.8)AlSi 3O 8 at 14-25 GPa and 1400-2400 °C. These experiments suggest that at subsolidus conditions the stable phase assemblages are hollandite-I + jadeite + stishovite (at pressures up to ˜20 GPa), hollandite-II + jadeite + stishovite (at pressures between ˜ 20 and ˜ 24 GPa), and hollandite-II + calcium ferrite-type NaAlSiO 4 + stishovite (at pressures > ˜ 24 GPa), where hollandite-I and hollandite-II are distinguished by their chemical compositions and phase diagram topology. The maximum NaAlSi 3O 8 in hollandite occurs at ˜ 22 GPa, and its fraction is positively correlated to temperature, attaining a value of ˜ 51 mol% at 2200 °C. At supersolidus conditions the solidus and liquidus phases around 14 GPa are hollandite-I and jadeite, respectively; at ˜ 22 GPa, however, the solidus phase is jadeite while the liquidus phase is either stishovite or hollandite-II with a very low fraction of NaAlSi 3O 8. These experimental results therefore suggest that lingunite with the hollandite structure and ˜ 90 mol% NaAlSi 3O 8, found in some meteorites, is a disequilibrium product. It is similarly proposed that the phase with the structure of jadeite but the composition of plagioclase, found along with lingunite, is also a disequilibrium phase.

  4. Modeling of thermal stratification in main coolant piping under natural circulation for assessment of reactor pressure vessel thermal shock conditions using RELAP5/MOD3.2 code

    International Nuclear Information System (INIS)

    The cold and hot legs are split in the WWER-1000 model for RELAP/MOD3.2 code into two vertical levels to model the stratified flows in the main coolant piping in case of water injection by core cooling systems. The model is tested using the cold leg stratification and mixing experimental data. The comparison of the results for a leak through the open pressurizer safety valve with experimental data showed improvement of transient behavior. The model can be used for the evaluation of anticipated thermal stratification phenomena in cold legs

  5. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity

    International Nuclear Information System (INIS)

    A nonlinear stability threshold for rotation in a couple-stress fluid heated from below saturating a porous medium with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. The effects of couple-stress parameter, variable dependent viscosity, medium permeability, Taylor number and Darcy–Brinkman number on the onset of convection are also analysed. (paper)

  6. Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-attachment along the Suction Surface of a Low Pressure Turbine Blade

    Science.gov (United States)

    Ozturk, B.; Schobeiri, M. T.; Ashpis, David E.

    2005-01-01

    The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the suction surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on suction surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the suction surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re=110,000.

  7. The MOX fuel effective behavior in nominal pressure water reactor condition: Micro-mechanical modeling by non uniform transformation field analysis; Modelisation du comportement effectif du combustible MOX par une analyse micromecanique en champs de transformation non uniformes

    Energy Technology Data Exchange (ETDEWEB)

    Largenton, R. [Dpt MMC EDF RD, Site des Renardieres, Avenue des Renardieres, 77818 Moret-sur-Loing (France); Michel, J.C.; Suquet, P. [LMA CNRS, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, (France); Masson, R. [CEA, DEN, DEC, Cadarache, 13108 Saint-Paul-Lez-Durance Cedex (France)

    2011-07-01

    The heterogeneous distribution of the plutonium in the MOX nuclear fuel involves that the modeling of its behavior, under irradiation in pressure water reactor (PWR), is realized by the construction of macroscopic laws taking into account the microstructural effects. To homogenize this local problem, we chose a Non uniform Transformation Field Analysis (J. C. Michel, P. Suquet, Int. J. Solids Struct. 40 (2003) 6937-6955). We thus present here, the works led on this model to adapt it to the MOX fuel behavior in PWR nominal conditions, as well as a comparison of the global and local results of this model to reference calculations. (authors)

  8. Pressure Sores

    Science.gov (United States)

    ... skin and tissue. They usually are caused by sitting or lying in one position for too long. This puts pressure on certain ... pressure sores? Pressure sores usually are caused by sitting or lying in one position for too long. This puts pressure on certain ...

  9. Design of an R.F. Excited Helium Neon Visible Gas Laser and Study of the Optimal Conditions for Gas Mixtures and Pressures

    Directory of Open Access Journals (Sweden)

    D. P. Juyal

    1972-10-01

    Full Text Available Design of a continuous were helium-neon visible gas laser has been described. Brewster angle window of fused quartz and external concave mirrors of B.S.C. glass have been used in the fabrication of resonant cavity. An RF oscillator having variable frequency in the range of 20-30 MHz and an out-put power of about 50 watts served as excitation source. Different mixture ratios of He and Ne have been tried and for each ratio power output was measured versus total pressure inside the discharge tube keeping cavity length constant. The optimum power output has been obtained for 5:1 mixture at 1.4 torr for a tube of length 55 cm and internal diameter 0.5 cm. Laser action at 1.53 meu has been achieved.`

  10. A coupled numerical analysis of shield temperatures, heat losses and residual gas pressures in an evacuated super-insulation using thermal and fluid networks - Part I: Stationary conditions

    Science.gov (United States)

    Reiss, H.

    2004-04-01

    This paper describes numerical simulations, using thermal networks, of shield temperatures and radiative and conductive heat losses of a super-insulated cryogenic storage tank operating at 77 K. Interactions between radiation and conductive heat transfer modes in the shields are investigated, by calculation of local shield temperatures. As a new method, fluid networks are introduced for calculation of stationary residual gas pressure distribution in the evacuated multilayer super-insulation. Output from the fluid network is coupled to the iterative thermal network calculations. Parameter tests concern thickness and emissivity of shields, degree of perforation, residual gas sources like desorption from radiation shields, spacers and container walls, and permeation from the inner container to the evacuated insulation space. Variations of either a conductive (thickness of Al-film on Mylar) or a radiative parameter (thermal emissivity) exert crosswise influences on the radiative or conductive heat losses of the tank, respectively.

  11. Pressure locking test results

    Energy Technology Data Exchange (ETDEWEB)

    DeWall, K.G.; Watkins, J.C.; McKellar, M.G.; Bramwell, D. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [and others

    1996-12-01

    The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.{close_quotes} Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; the authors will publish the results of their thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated with pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions.

  12. An AlN cantilever for a wake-up switch triggered by air pressure change

    International Nuclear Information System (INIS)

    This research reports an AlN cantilever with an air chamber for a wake-up switch triggered by air pressure change. The proposed sensor is designed to fulfil both high sensitivity and low power consumption. By combining an air chamber to the one side of the AlN cantilever surface, the barometric pressure change generates a piezoelectric voltage. Thus, a wake-up switch triggered by air pressure change can be achieved using an AlN cantilever. The size of the fabricated AlN cantilever was 2000 ?m × 1000 ?m × 2 ?m. The sensitivity to static differential pressure was 11.5 mV/Pa at the range of ?20 Pa to 20 Pa. We evaluated the response of the sensor, which was composed of the AlN cantilever and the chamber of 60 ml in volume, when air pressure change was applied. The output voltage increased with increasing the applied air pressure change. It was observed that the maximum output voltage of 50 mV was generated when the air pressure change was 13 Pa

  13. Experimental investigations of uncovered-bundle heat transfer and two-phase mixture-level swell under high-pressure low heat-flux conditions

    International Nuclear Information System (INIS)

    Results are reported from a series of uncovered-bundle heat transfer and mixture-level swell tests. Experimental testing was performed at Oak Ridge National Laboratory in the Thermal Hydraulic Test Facility (THTF). The THTF is an electrically heated bundle test loop configured to produce conditions similar to those in a small-break loss-of-coolant accident. The objective of heat transfer testing was to acquire heat transfer coefficients and fluid conditions in a partially uncovered bundle. Testing was performed in a quasi-steady-state mode with the heated core 30 to 40% uncovered. Linear heat rates varied from 0.32 to 2.22 kW/m.rod (0.1 to 0.68 kW/ft.rod). Under these conditions peak clad temperatures in excess of 1050 K (14300F) were observed, and total heat transfer coefficients ranged from 0.0045 to 0.037 W/cm2.K (8 to 65 Btu/h.ft2.0F). Spacer grids were observed to enhance heat transfer at, and downstream of, the grid. Radiation heat transfer was calculated to account for as much as 65% of total heat transfer in low-flow tests

  14. Smoluchowski Equations for Agglomeration in Conditions of Variable Temperature and Pressure and a New Scaling of Rate Constants: Application to Nozzle-Beam Expansion.

    Science.gov (United States)

    Chaiken, J; Goodisman, J; Kornilov, O

    2015-07-01

    The Smoluchowski equations provide a rigorous and efficient means for including multiple kinetic pathways when modeling coalescence growth systems. Originally written for a constant temperature and volume system, the equations must be modified if temperature and pressure vary during the coalescence time. In this paper, the equations are generalized, and adaptations appropriate to the situation presented by supersonic nozzle beam expansions are described. Given rate constants for all the cluster-cluster reactions, solution of the Smoluchowski equations would yield the abundances of clusters of all sizes at all times. This is unlikely, but we show that if these rate constants scale with the sizes of the reacting partners, the asymptotic (large size and large time) form of the cluster size distribution can be predicted. Experimentally determined distributions for He fit the predicted asymptotic distribution very well. Deviations between predicted and observed distributions allow identification of special cluster sizes that is, magic numbers. Furthermore, fitting an observed distribution to the theoretical form yields the base agglomeration cross section, from which all cluster-cluster rate constants may be obtained by scaling. Comparing the base cross section to measures of size and reactivity gives information about the coalescence process. PMID:26067086

  15. Application of LITGs diagnostics to trace detection of NOx in high pressure combustors: a propedeutic study in a cell at controlled conditions

    International Nuclear Information System (INIS)

    The field of the interference pattern of two laser beams, either on or off resonance with an allowed transition in a medium, generates spatial modulations of its complex refractive index called Laser Induced Gratings (LIGs). After the excitation, the subsequent release of internal energy in the form of heat, in gases, due to collisional relaxation, may lead to the formation of thermal gratings (LITGs). The temporal evolution of a LIG can be investigated by using a CW laser as a probe. The temporal behavior of LITGs depends on the rate of the energy thermalization, e.g. a fast energy release generates a standing acoustic wave and a stationary density modulation with equal amplitudes, whereas a slow energy release favours the formation of the stationary density modulation whereas the development of the acoustic contribution is suppressed. In case of a multi-step thermalization process, with different time constants involved, oscillatory and stationary contributions to LITGs can be observed. LITGs experiments have been performed with NO2 molecules diluted in different buffer gases in order to establish the possibilities to trace this species at high pressure and high temperature in combustion exhaust pipes

  16. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    International Nuclear Information System (INIS)

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible

  17. Conditions within a bentonite-based, full-scale tunnel seal after 5 years of exposure to elevated temperature and pore water pressure

    International Nuclear Information System (INIS)

    A major international experiment, demonstrating technologies for tunnel sealing at full-scale was conducted at Canada Underground Research Laboratory between 1998 and 2004. The participants in this Tunnel Sealing Experiment (TSX) were AECL, Andra, JNC and during the pre-thermal phase of the experiment the USDoE (via the Waste Isolation Pilot Project (WIPP)). Two bulkheads were installed; one consisted of high-performance concrete and the other of highly compacted sand-bentonite material. The performance of these two bulkheads was monitored throughout the experiment in order to evaluate the influence of elevated hydraulic head (4 MPa) and chamber temperature (up to 85 C) on these materials. This paper primarily describes the density, and moisture conditions within and adjacent to the clay bulkhead portion of the TSX at the time of experiment decommissioning. The clay bulkhead was extensively sampled in the course of TSX decommissioning, allowing for development of a detailed density, moisture content and tracer distribution profiles for the clay bulkhead. This allows for comparison of the as-built and the end-of-test conditions within the clay bulkhead. (authors)

  18. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    Science.gov (United States)

    Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-01

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  19. 40 CFR 86.145-82 - Calculations; particulate emissions.

    Science.gov (United States)

    2010-07-01

    ...New Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty...without prior EPA approval. (iii) If Pb is assumed = 0...barometric pressure, in Hg. (iii) Pip = pressure elevation...barometric pressure, in. Hg. (iii) Pib = pressure...

  20. Pressure ulcer

    Science.gov (United States)

    Bedsore; Decubitus ulcer ... form. You are more likely to get a pressure ulcer if you: Use a wheelchair or stay in ... Symptoms of a pressure ulcer are: Red skin that gets worse over time The area forms a blister, then an open sore Pressure sores ...

  1. High pressure melt ejection

    International Nuclear Information System (INIS)

    Recent probabilistic risk assessments have identified the potential for reactor pressure vessel failure while the reactor coolant system is at elevated pressure. The analyses postulate that the blowdown of steam and hydrogen into the reactor cavity will cause the core material to be swept from the cavity region into the containment building. The High Pressure Melt Streaming (HIPS) program is an experimental study of the high pressure ejection of molten material and subsequent interactions within a concrete cavity. The program focuses on using prototypic system conditions and scaled models of reactor geometries to accurately simulate the ex-vessel processes during high-pressure accident sequences. Scaling analyses of the experiment show that the criteria established for core debris removal from the cavity are met or exceeded. Tests are performed at two scales, representing 1/10th and 1/20th linear reproductions of the Zion reactor plant. Results of the 1/20th scale tests are presented

  2. Fluid pressure balanced seal

    Science.gov (United States)

    Marsh, H. W. (inventor)

    1966-01-01

    A seal which increases in effectiveness with increasing pressure is presented. The seal's functional capability throughout both static and dynamic operation makes it particularly useful for sealing ball valve ports. Other features of the seal include the ability to seal two opposed surfaces simultaneously, tolerance of small misalignments, tolerance of wide temperature ranges, ability to maintain positive sealing contact under conditions of internal or external pressurization, and ability to conform to slight irregularities in seal or surface contours.

  3. Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning

    International Nuclear Information System (INIS)

    With growing industrialization in power sector, air is being polluted with a host of substances-most conspicuously with suspended particulate matter emanating from coal-fired thermal power plants. Flue gas conditioning, especially in such power plants, requires in situ generation of ammonia. In the present paper, experiments for kinetic study of hydrolysis of urea have been conducted using a borosil glass reactor, first without stirring followed by with stirring. The study reveals that conversion increases exponentially with an increase in temperature and feed concentration. Furthermore, the effect of stirring speed, temperature and concentration on conversion has been studied. Using collision theory, temperature dependency of forward rate constant has been developed from which activation energy of the reaction and the frequency factors have been calculated. It has been observed that the forward rate constant increases with an increase in temperature. The activation energy and frequency factor with stirring has been found to be 59.85 kJ/mol and 3.9 x 106 min-1 respectively with correlation co-efficient and standard deviation being 0.98% and ±0.1% in that order.

  4. Upgrading of existing NPPs with 440 and 1000 MW WWER type pressurized water reactors for severe external loading conditions. Proceedings. Working material. V. 1, 2

    International Nuclear Information System (INIS)

    The Seminar was intended to provide the opportunity for the exchange of updated information concerning the state-of-the-art related to structural safety of the WWER 440 and 1000 MW nuclear power plants operating or under construction in the Russian Federation and several Eastern European countries. Codes and standards, design assumptions, seismic upgrading and requalification activities, recent verification by experimental methods as well as the corresponding reanalysis and reevaluation procedures were included in the scope. Also presented and discussed were the results of recent studies of typical structures and components under seismic loading. The Seminar was divided into five working sessions. Each session consisted of several presentations by invited speakers and extensive discussions. The topic of discussions involved the following: standards used during design phase, input load definitions and criteria, evaluation of as-built conditions and walk down information, site-specific dynamic response of structures based on recent studies and evaluation of results, capacity evaluations of components and systems based on updated acceptance criteria and strengthening concepts, functional qualification of active mechanical and electrical components and systems

  5. Management of the coastal biophysical environment in tropical Queensland under conditions of heavy developmental pressure: the case of tourist resorts and acid sulphate soils

    Directory of Open Access Journals (Sweden)

    Patricia Erfurt-Haupt

    2008-09-01

    Full Text Available La côte tropicale du Queensland est confrontée à un accroissement rapide de la population. Les fortes pressions anthropiques pèsent sur le milieu biophysique, qui comprend notamment a plus grande île de sable du monde, un site classé Patrimoine de l’Humanité, Port Hinchinbrook et Fraser Island.  Malgré l’existence d’une législation nationale orientée vers la préservation de l’environnement, il est manifeste que peu d’attention est accordée aux effets à long terme des sites touristiques et du développement de l’urbanisation sur ces franges côtières sensibles. L’aspect massif des flux de visiteurs et leurs impacts sur le milieu naturel a été identifié comme un sujet d’inquiétude particulier dans certaines régions. La connaissance des impacts sur la géomorphologie côtière souterraine est très réduite et les choix de développement sont souvent faits dans l’ignorance ou au mépris de la présence répandue de terrains de sulfate d’acide dans ce milieu côtier. Des sols réactifs comme ceux-là peuvent affecter, et affectent, grandement les résultats géophysiques d’un développement lorsqu’ils sont connus. Des études de cas sur le problème des sols de sulfate d’acide suggèrent qu’une partie de la solution pour le gouvernement de l’Etat du Queensland est d’imposer des normes obligatoires pour le développement du tourisme dans la zone côtière.The tropical coast of Queensland, Australia is experiencing rapid population and tourism growth. Heavy development pressure is being placed on the biophysical environment, which includes the largest sand island in the world (World Heritage listed, Fraser Island. Despite the existence of State planning legislation oriented towards environmental sustainability, it is apparent that little, if any, regard is being paid to the long-term effects of resort and canal-estate development on the underlying biophysical environment of the coast and islands.  While the remarkable surface features of the tropical coastal environment such as the surf beaches, the unique dune lakes, and the coastal vegetation, as well as the prolific wildlife, are used as selling points for new settlement and above all tourism, little is known or apparently of major concern with respect to the long term environmental impact of coastal development. While the crowding effect of large numbers of visitors and their impact on the natural environment - through significant degradation, site hardening or lack of proper on-site management – has been identified as a particular problem in certain areas, there is little knowledge of impacts on the underlying coastal geomorphology. In particular, developmental choices are often made in ignorance of, or disregard of, the widespread existence of tropical acid sulfate soils in that coastal environment. Reactive soils such as these can, and do, greatly affect the biophysical outcomes of a development if they are exposed. This paper documents such impacts in the form of a case study of the acid sulfate soil problem in relation to the development of tourist resorts, and suggests that part of the solution is for the State Government to insist on enforceable standards relating to their development for tourism in the coastal zone. These would reduce the use by many resort owners of fancy golf course developments as an environmental cover up to make it look as if they put a lot of effort into protecting the environment ….

  6. Price pressures

    OpenAIRE

    Hendershott, Terrence; Menkveld, Albert J.

    2010-01-01

    We study price pressures in stock prices—price deviations from fundamental value due to a risk-averse intermediary supplying liquidity to asynchronously arriving investors. Empirically, twelve years of daily New York Stock Exchange intermediary data reveal economically large price pressures. A $100,000 inventory shock causes an average price pressure of 0.28% with a half-life of 0.92 days. Price pressure causes average transitory volatility in daily stock returns of 0.49%. Price pressure ef...

  7. Proceedings of the twenty-fourth water reactor safety information meeting. Volume 2: Reactor pressure vessel embrittlement and thermal annealing; Reactor vessel lower head integrity; Evaluation and projection of steam generator tube condition and integrity

    International Nuclear Information System (INIS)

    This three-volume report contains papers presented at the Twenty-Fourth Water Reactor Safety Information Meeting held at the Bethesda Marriott Hotel, Bethesda, Maryland, October 21--23, 1996. The papers are printed in the order of their presentation in each session and describe progress and results of programs in nuclear safety research conducted in this country and abroad. Foreign participation in the meeting included papers presented by researchers from Czech Republic, Finland, France, Japan, Norway, Russia and United Kingdom. This volume is divided into the following sections: reactor pressure vessel embrittlement and thermal annealing; reactor vessel lower head integrity; and evaluation and projection of steam generator tube condition and integrity. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

  8. Pressure vessel

    International Nuclear Information System (INIS)

    In a pressure vessel comprising a cylindrical main body of a pressure vessel, a plurality of pump shaft-penetration holes, and an end plate having nozzles for mounting pumps disposed at the outer side thereof corresponding to the pump shaft penetration holes, in which the circumferential edge of the end plate is joined to the end of the main body of the pressure vessel such that nozzles situate at the outer side of the main body of the pressure vessel, in order to prevent displacement of the center line of the nozzle due to the deformation of the pressure vessel, the end plate is shaped as a partially spherical shell concaved toward the nozzle, and the ratio of the wall thickness between the end of the main body of the pressure vessel and the circumferential portion of the end plate is properly adjusted while considering the inner radius of the main body of the pressure vessel, the inner radius of the end plate, the Young's coefficient of the main body of the pressure vessel, a Young's coefficient of the end plate, the Poisson's ratio of the main body of the pressure vessel, the Poisson's ratio of the end plate. As a result, the amount of deformation of the main body of the pressure vessel, and the amount of displacement of the joined portion between the main body of the pressure vessel and the end plate are made substantially equal, to prevent the displacement of the center line of the nozzle due to deformation of the main body of the pressure vessel and the end platdy of the pressure vessel and the end plate. (N.H.)

  9. Carbon dioxide, temperature, salinity, and barometric pressure collected via surface underway survey from R/V McArthur II in the eastern North and South Pacific from July 30, 2006 to July 26, 2007 (NODC Accession 0084052)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0084052 includes underway chemical, meteorological, and physical data collected from MCARTHUR II in Coastal Waters of SE Alaska, Cordell Bank...

  10. Pressure sensor

    International Nuclear Information System (INIS)

    The pressure sensor will be used for pressure measurement in high-temperature liquids, in particular for Na or K during fast breeder operation. It has a soft membrane which is unshielded at the pressure medium side and can actuate a rigid membrane an the other side by means of a botton element. The displacement of the rigid membrane is proportional to the difference between the liquid pressure and a reference gas pressure. The displacement can be measured by means of a capacity displacement measuring instrument, using a fixed plate as reference. Absolute calibration is performed by admitting pressurized gas into the zone between the membranes and into the zone between rigid membrane and fixed plate. The coupling between the soft and the rigid membrane is thus interrupted. (DG)

  11. 40 CFR 92.132 - Calculations.

    Science.gov (United States)

    2010-07-01

    ...of inlet air ( °F...standard temperature and pressure (ft3 ...TDM =Temperature of methanol...dilution air, °R...Barometric pressure during test... TDM =Temperature of ethanol...dilution air, °R...Barometric pressure during...

  12. Pressure Core Characterization

    Science.gov (United States)

    Santamarina, J. C.

    2014-12-01

    Natural gas hydrates form under high fluid pressure and low temperature, and are found in permafrost, deep lakes or ocean sediments. Hydrate dissociation by depressurization and/or heating is accompanied by a multifold hydrate volume expansion and host sediments with low permeability experience massive destructuration. Proper characterization requires coring, recovery, manipulation and testing under P-T conditions within the stability field. Pressure core technology allows for the reliable characterization of hydrate bearing sediments within the stability field in order to address scientific and engineering needs, including the measurement of parameters used in hydro-thermo-mechanical analyses, and the monitoring of hydrate dissociation under controlled pressure, temperature, effective stress and chemical conditions. Inherent sampling effects remain and need to be addressed in test protocols and data interpretation. Pressure core technology has been deployed to study hydrate bearing sediments at several locations around the world. In addition to pressure core testing, a comprehensive characterization program should include sediment analysis, testing of reconstituted specimens (with and without synthetic hydrate), and in situ testing. Pressure core characterization technology can be used to study other gas-charged formations such as deep sea sediments, coal bed methane and gas shales.

  13. Critical CRBR core pressure

    International Nuclear Information System (INIS)

    The conditions are detailed under which gas pressure will cause or initiate failure in the structural containment of the fuel core. The Clinch River Breeder Reactor Plant is the prototype structure. Two general classes of problems have been studied, representing two entirely distinct configurations of containment failure. The first model determines the minimum pressure to lift a portion or the entire core from its containment. The second model estimates the critical pressure above which the fuel rods interior to the hexagonal fuel can warp, leading to blockage of the gas passages. Such blockage might cause further buildup of the gas pressure to a level causing the failure of the fuel rod containment in the hexagonal fuel container

  14. Battling High Blood Pressure

    Medline Plus

    Full Text Available ... Transcript High blood pressure increases your risk for heart attack, stroke and other dangerous conditions. Now, the latest statistics show the hypertension-related death rate rose more than 23 percent ... were heart disease, stroke, cancer and diabetes…. About 70 million ...

  15. Large diamonds grown at high pressure conditions

    Scientific Electronic Library Online (English)

    H., Kanda.

    Full Text Available A technique has been established to grow large diamonds up to 2 cm. The crystals are bulky polyhedron with yellow, blue, green or brown color as well as colorless, which depend on impurities. The impurities incorporated into the diamond are limited, i.e. nitrogen, boron, nickel, cobalt, silicon and [...] phosphorus.

  16. Análise termodinâmica visando estabelecer as condições ideais de síntese da ferrita de cobre a partir de solução aquosa a baixa pressão Thermodynamic analysis to establish the ideal conditions for copper ferrite synthesis from aqueous solutions at low pressure

    Directory of Open Access Journals (Sweden)

    F. Moore

    1999-05-01

    Full Text Available A literatura assinala que a ferrita de cobre é uma das ferritas possíveis de obtenção a partir da solução aquosa a baixa pressão, isto é, um precipitado misto de hidróxidos de ferro e de cobre submetido a um tratamento de cristalização em temperaturas e pressões ordinárias (inferior a 100 ° C e aproximadamente 1 atm de pressão resultará em ferrita de cobre cristalina. Utilizando o Programa de Aplicativos HSC Chemistry for Windows 3.0, foram construídos diagramas eH-pH para grande número de atividades de Cu e Fe na solução aquosa, na condição de atividade de cobre igual à ferro. A partir destes gráficos uma solução aquosa potencialmente neutra, diagramas de pFe-pH (onde pFe=-loga Fe foram construídos para cada uma das 3 temperaturas selecionadas (25, 150 e 300 ° C. A análise dos diagramas revela que o domínio pFe-pH de estabilidade da ferrita cuprosa, CuFeO2, decresce com a elevação do sistema de 25 °C para 150 °C e 300 °C. Entretanto, as previsões dos diagramas obtidos concordam bem com os fatos experimentalmente conhecidos na literatura.The literature on the subject points out that copper ferrite is one of the ferrites possible to be obtained from aqueous solutions at low pressures, that is, a mist precipitate of iron and copper hydroxides submitted to a crystallization treatment at ordinary temperatures and pressures (lower than 100° C and at approximately 1 atm pressure will result in the form of crystalline copper ferrite. Using the HSC Chemistry for Windows 3.0 software, eH -pH diagrams for sufficiently large number of activities of Cu and Fe in the aqueous solutions, under condition of activity of copper=activity of iron, were constructed. From these diagrams, for a potentiometrically neutral aqueous solution, a pFe-pH diagram (where pFe=-loga Fe has been constructed for each of the three selected temperatures (25, 150 and 300° C. Furthermore, the predictions of the obtained diagrams are in good agreement with the experimentally known facts.

  17. Análise termodinâmica visando estabelecer as condições ideais de síntese da ferrita de cobre a partir de solução aquosa a baixa pressão / Thermodynamic analysis to establish the ideal conditions for copper ferrite synthesis from aqueous solutions at low pressure

    Scientific Electronic Library Online (English)

    F., Moore; K. M., Ribeiro; E. R., Almendra; T., Ogasawara.

    1999-05-01

    Full Text Available A literatura assinala que a ferrita de cobre é uma das ferritas possíveis de obtenção a partir da solução aquosa a baixa pressão, isto é, um precipitado misto de hidróxidos de ferro e de cobre submetido a um tratamento de cristalização em temperaturas e pressões ordinárias (inferior a 100 [...] ="Symbol">° C e aproximadamente 1 atm de pressão) resultará em ferrita de cobre cristalina. Utilizando o Programa de Aplicativos HSC Chemistry for Windows 3.0, foram construídos diagramas eH-pH para grande número de atividades de Cu e Fe na solução aquosa, na condição de atividade de cobre igual à ferro. A partir destes gráficos uma solução aquosa potencialmente neutra, diagramas de pFe-pH (onde pFe=-loga Fe) foram construídos para cada uma das 3 temperaturas selecionadas (25, 150 e 300 ° C). A análise dos diagramas revela que o domínio pFe-pH de estabilidade da ferrita cuprosa, CuFeO2, decresce com a elevação do sistema de 25 °C para 150 °C e 300 °C. Entretanto, as previsões dos diagramas obtidos concordam bem com os fatos experimentalmente conhecidos na literatura. Abstract in english The literature on the subject points out that copper ferrite is one of the ferrites possible to be obtained from aqueous solutions at low pressures, that is, a mist precipitate of iron and copper hydroxides submitted to a crystallization treatment at ordinary temperatures and pressures (lower than 1 [...] 00° C and at approximately 1 atm pressure) will result in the form of crystalline copper ferrite. Using the HSC Chemistry for Windows 3.0 software, eH -pH diagrams for sufficiently large number of activities of Cu and Fe in the aqueous solutions, under condition of activity of copper=activity of iron, were constructed. From these diagrams, for a potentiometrically neutral aqueous solution, a pFe-pH diagram (where pFe=-loga Fe) has been constructed for each of the three selected temperatures (25, 150 and 300° C). Furthermore, the predictions of the obtained diagrams are in good agreement with the experimentally known facts.

  18. Pressure gauge

    International Nuclear Information System (INIS)

    A hollow probe made of a material exhibiting magnetostriction is placed inside the enclosure where the pressure is to be determined. A coil to measure the probe's magnetic permeability is placed outside the enclosure, as near as possible to the probe. A second identical coil is placed elsewhere. A comparison between both coil currents gives the pressure in the enclosure. High sensitiviteis (0.07 at) are reported over a wide range (0-35 at). The instrument is ideal in situations where no electrical or mechanical signal transmission device is allowed through to be fitted into the pressure container, as is the case in fuel bundles in nuclear reactors, for example. (RW)

  19. Measuring Pressure

    Science.gov (United States)

    AMPS GK-12 Program,

    Students learn first-hand the relationship between force, area and pressure. They use a force sensor built from a LEGO® MINDSTORMS® NXT kit to measure the force required to break through a paper napkin. An interchangeable top at the end of the force sensor enables testing of different-sized areas upon which to apply pressure. Measuring the force, and knowing the area, students compute the pressure. This leads to a concluding discussion on how these concepts are found and used in engineering and nature.

  20. A transmission-line model of back-cavity dynamics for in-plane pressure-differential microphones.

    Science.gov (United States)

    Kim, Donghwan; Kuntzman, Michael L; Hall, Neal A

    2014-11-01

    Pressure-differential microphones inspired by the hearing mechanism of a special parasitoid fly have been described previously. The designs employ a beam structure that rotates about two pivots over an enclosed back volume. The back volume is only partially enclosed due to open slits around the perimeter of the beam. The open slits enable incoming sound waves to affect the pressure profile in the microphone's back volume. The goal of this work is to study the net moment applied to pressure-differential microphones by an incoming sound wave, which in-turn requires modeling the acoustic pressure distribution within the back volume. A lumped-element distributed transmission-line model of the back volume is introduced for this purpose. It is discovered that the net applied moment follows a low-pass filter behavior such that, at frequencies below a corner frequency depending on geometrical parameters of the design, the applied moment is unaffected by the open slits. This is in contrast to the high-pass filter behavior introduced by barometric pressure vents in conventional omnidirectional microphones. The model accurately predicts observed curvature in the frequency response of a prototype pressure-differential microphone 2?mm?×?1?mm?×?0.5?mm in size and employing piezoelectric readout. PMID:25373956

  1. Effect of attrition on SO{sub 2} capture by limestone under pressurized fluidized bed combustion conditions - comparison between a mathematical model of SO{sub 2} capture by single limestone particle under attrition condition and SO{sub 2} capture in a large-scale PFBC

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, T.; Peglow, M.; Sakuno, S.; Misawa, N.; Suzuki, N.; Ueda, H.; Sasatsu, H. [Niigata University, Niigata (Japan). Dept. of Chemistry and Chemical Engineering

    2001-12-01

    This paper evaluated the attrition rate of limestone and SO{sub 2} capture rate in a large scale pressurized fluidized bed combustor. The average attrition rate (reduction rate of radius) was found to be approximately 0.2-0.7 nm/s. The SO{sub 2} capture rate per unit external surface area of bed material was found to be independent of SO{sub 2} concentration in the flue gas. A mathematical model of SO{sub 2} capture by single limestone particle under attrition conditions was proposed. Apparent reaction order with respect to SO{sub 2} concentration was close to zero when attrition was taken into consideration. It was suggested that the rate of SO{sub 2} capture in the present PFBC was governed by the limestone attrition.

  2. Pressurized Thermal Shock, Pts

    International Nuclear Information System (INIS)

    Pressurized Thermal Shock (Pts) refers to a condition that challenges the integrity of the reactor pressure vessel. The root cause of this problem is the radiation embrittlement of the reactor vessel. This embrittlement leads to an increase in the reference temperature for nil ductility transition (RTNDT). RTNDT can increase to the point where the reactor vessel material can loose fracture toughness during overcooling events. The analysis of the risk of having a Pts for a specific plant is a multi-disciplinary problem involving probabilistic risk analysis (PRA), thermal-hydraulic analysis, and ultimately a structural and fracture analysis of the vessel wall. The PRA effort involves the postulation of overcooling events and ultimately leads to an integrated risk analysis. The thermal-hydraulic effort involves the difficult task of predicting the system behavior during a postulated overcooling scenario with a special emphasis on predicting the thermal and mechanic loadings on the reactor pressure vessel wall. The structural and fracture analysis of the reactor vessel wall relies on the thermal-hydraulic conditions as boundary conditions. The US experience has indicated that medium and large diameter primary system breaks dominate the risk of Pts along with scenarios that involve a stuck open valve (and associated system cooldown) that recloses resulting in system re-pressurization while the vessel wall is cool.

  3. A separate effect test on the cooling behavior in a pressurized water reactor core under a low reflooding rate condition by using ATLAS and RELAP5/MOD3.3 code assessment

    International Nuclear Information System (INIS)

    Research highlights: ? A separate effect test was performed for the core quench behavior in a PWR core. ? A low reflooding rate test was performed for APR1400 by using the ATLAS. ? A DVI, a reverse heat transfer from SGs and the steam binding effect was simulated. ? The test data were used to assess the reflood models of the RELAP5/MOD3. ? The modified version of RELAP5/MOD3.3 showed better agreement with the test data. - Abstract: A separate effect test was performed on the cooling behavior in a PWR core under a low reflooding rate condition by using the ATLAS (Advanced Thermal-Hydraulic Test Loop for Accident Simulation) which is a thermal-hydraulic integral effect test facility for the pressurized water reactors APR1400 and OPR1000. Although several integral tests for the reflood phase of a large break loss of coolant accident (LBLOCA) of APR1400 have been performed with the ATLAS, the previous integral effect tests for the reflood phase of a LBLOCA are not easily simulated by existing codes, such as the RELAP5/MOD3, due to a unique phenomena in ATLAS, that resulted from an injection of large amount of subcooled water onto the heated wall of which temperature was higher than the target value. Therefore, there is a need to perform a separate effect test under a low reflooding rate condition using the ATLAS to help validate the RELAP5 reflood models. The present LB-CL-15 test was performed to validate the RELAP5 reflood models for a core quench phenomenon us for a core quench phenomenon under a low flow rate ECC injection condition. Separate effect test data for APR1400 could be obtained by using the ATLAS, which could simulate a direct vessel injection, a reverse heat transfer from steam generators and the steam binding effect, etc. The experimental data were used to assess the reflood models of the safety analysis codes of the original RELAP5/MOD3.3 and a modified version of RELAP5/MOD3.3. The modified version showed better agreement with the test data than the original version.

  4. Pressurized-thermal-shock tests

    International Nuclear Information System (INIS)

    Pressurized-thermal-shock experiments are required to validate methods of fracture analysis to establish the degree of conservatism or accuracy involved in predictions of flaw behavior under certain accident conditions. By using methods and facilities developed for this purpose we can simulate materials and loading regimes to evaluate the integrity of flawed reactor pressure vessels subjected to pressurized-thermal-shock transients. These accidents involve small-break loss-of-coolant accidents, steamline breaks, and other similar overcooling accident scenarios involving combined temperature and pressure transients

  5. Reactor pressure boundary materials

    International Nuclear Information System (INIS)

    With a long-term operation of nuclear power plants, the component materials are degraded under severe reactor conditions such as neutron irradiation, high temperature, high pressure and corrosive environment. It is necessary to establish the reliable and practical technologies for improving and developing the component materials and for evaluating the mechanical properties. Especially, it is very important to investigate the technologies for reactor pressure boundary materials such as reactor vessel and pipings in accordance with their critical roles. Therefore, this study was focused on developing and advancing the microstructural/micro-mechanical evaluation technologies, and on evaluating the neutron irradiation characteristics and radiation effects analysis technology of the reactor pressure boundary materials, and also on establishing a basis of nuclear material property database

  6. Mechanical Buckling of Artery under Pulsatile Pressure

    Science.gov (United States)

    Liu, Qin; Han, Hai-Chao

    2012-01-01

    Tortuosity that often occurs in carotid and other arteries has been shown to be associated with high blood pressure, atherosclerosis, and other diseases. However the mechanisms of tortuosity development are not clear. Our previous studies have suggested that arteries buckling could be a possible mechanism for the initiation of tortuous shape but artery buckling under pulsatile flow condition has not been fully studied. The objectives of this study were to determine the artery critical buckling pressure under pulsatile pressure both experimentally and theoretically, and to elucidate the relationship of critical pressures under pulsatile flow, steady flow, and static pressure. We first tested the buckling pressures of porcine carotid arteries under these loading conditions, and then proposed a nonlinear elastic artery model to examine the buckling pressures under pulsatile pressure conditions. Experimental results showed that under pulsatile pressure arteries buckled when the peak pressures were approximately equal to the critical buckling pressures under static pressure. This was also confirmed by model simulations at low pulse frequencies. Our results provide an effective tool to predict artery buckling pressure under pulsatile pressure. PMID:22356844

  7. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    International Nuclear Information System (INIS)

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated

  8. Modeling of radon transport in unsaturated soil

    Science.gov (United States)

    Chen, Chuan; Thomas, Donald M.; Green, Richard E.

    1995-08-01

    This study applies a recently developed model, LEACHV, to simulate transport of radon through unsaturated soil and compares calculated soil radon activities against field-measured values. For volatile and gas phase transport, LEACHV is modified from LEACHP, a pesticide version of LEACHM, a well-documented one-dimensional model for water and chemical movement through unsaturated soil. LEACHV adds consideration of air temperature changes and air flow driven by barometric pressure change to the other soil variables currently used in LEACHP. It applies diurnal barometric pressure and air temperature changes to reflect more accurately the typical field conditions. Sensitivity analysis and simulated results have clearly demonstrated the relative importance of barometric pressure change, rainfall events, changes in water content, gas advection, and radon source term in radon transport process. Comparisons among simulated results illustrated that the importance of barometric pressure change and its pumping phenomenon produces both fluctuation in soil gas radon activities and an elevation of the long-term average radon activity in the shallow soil. Barometric pressure pumping was found to produce an effect on radon activity in shallow soils of an equal magnitude to the distributed source parameter. Comparison between measured and simulated soil radon activities showed that LEACHV can provide realistic estimates of radon activity concentration in the soil profile.

  9. Characterization of the flowing afterglows of an N2-O2 reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NO? UV intensity variation with the N and O atom densities

    International Nuclear Information System (INIS)

    The flowing afterglow of an N2-O2 discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N2+ 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2-O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (abthe NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using the actinometry method: the density of N atoms decreases from its maximum value at 0% O2 as the percentage of O2 is increased while the density of O atoms increases, almost linearly, as a function of the percentage of O2, as in the afterglow. The intensity variation of the NO? UV emission as a function of the percentage of O2 is characterized by a maximum around 0.6% O2 (2 Torr) followed by an approximately exponential decay. We observe that, in the 0-1% O2 range, the UV emission is limited by the availability of O atoms. Beyond this point, the decrease of the UV intensity follows the decrease in the N atom density, while on the average, the O atom density keeps on increasing with O2%. Erosion of polymer microspheres is found to be strongest at the chamber axis when no O2 is present, implying a dominant early afterglow. Adding even only 1% O2 causes a strong quenching of the N2 metastable species, leading to a dominant late afterglow and therefore considerably reducing the etching rate at the axis. In contrast, at 5 cm from the axis under the same operating conditions, a dominant late afterglow prevails; in the absence of oxygen, erosion is negligible, but it increases regularly as O2 is introduced, following approximately the increase in the O atom density

  10. Solar thermal barometer; Barometre solaire thermique

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-06-15

    In 2008, the European solar thermal market put on a strong spurt only to mark time in 2009 with about 4.2 million m{sup 2} installed, which is 450000 m{sup 2} less year-on-year. The main reasons of the decrease is the financial crisis and the low oil price, other reasons more specific to the country exist, for instance the property crisis has dragged the Spanish market down. In 2009, the solar thermal collector surface area in service in the European Union is of the magnitude of 32.6 million m{sup 2}, equivalent to a capacity of 22.8 GWTh. The solar thermal sector is one of the renewable sectors that creates the highest number of jobs and wealth, partly because the vast majority of the system components sold in Europe are produced in Europe and partly because the sale, installation fitting and maintenance are labour-intensive. In 2009, there were 50000 direct or indirect jobs in the European solar thermal sector. The main European actors in this sector are GREENoneTEC, Bosch-Thermotechnik, Viessmann, Vaillant and Solvis. No clear recovery is expected before 2011. (A.C.)

  11. Solid biomass barometer; Barometre biomasse solide

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-11-15

    The primary energy production from solid biomass in the European Union reached 79.3 Mtoe in 2010 which implies a growth rate of 8% between 2009 and 2010. The trend, which was driven deeper by Europe's particularly cold winter of 2009-2010, demonstrates that the economic down-turn failed to weaken the member states' efforts to structure the solid biomass sector. Heat consumption rose sharply: the volume of heat sold by heating networks increased by 18% and reached 6.7 Mtoe and if we consider the total heat consumption (it means with and without recovery via heating networks) the figure is 66 Mtoe in 2010, which amounts to 10.1% growth. The growth of electricity production continued through 2010 (8.3% up on 2009) and rose to 67 TWh but at a slower pace than in 2009 (when it rose by 11.3% on 2008). The situation of the main producer countries: Sweden, Finland, Germany and France is reviewed. It appears that cogeneration unit manufacturers and biomass power plant constructors are the main beneficiaries of the current biomass energy sector boom. There is a trend to replace coal-fired plants that are either obsolete or near their end of life with biomass or multi-fuel plants. These opportunities will enable the industry to develop and further exploit new technologies such as gasification, pyrolysis and torrefaction which will enable biomass to be turned into bio-coal. (A.C.)

  12. DETERMINATION OF LAMINAR FLAME SPEED OF METHANE-AIR FLAMES AT SUBATMOSPHERIC CONDITIONS USING THE CONE METHOD AND CH* EMISSION / DETERMINACIÓN DE LA VELOCIDAD DE DEFLAGRACIÓN LAMINAR DE LLAMAS METANO -AIRE A CONDICIONES SUBATMOSFÉRICAS EMPLEANDO EL MÉTODO DEL CONO Y LA EMISIÓN DE CH*

    Scientific Electronic Library Online (English)

    LUIS FERNANDO, LONDOÑO; CARLOS ESTEBAN, LÓPEZ; FRANCISCO, CADAVID; HUGO, BURBANO.

    2013-08-01

    Full Text Available Mediciones experimentales de la velocidad de deflagración laminar para llamas de premezcla metano-aire fueron realizadas para distintos dosados a condiciones subatmosféricas, 0,852 bar y 298 K. Las llamas fueron obtenidas utilizando un quemador de puerto rectangular el cual cuenta con un sistema de [...] refrigeración por agua, necesario para mantener la temperatura de la premezcla constante. Se utilizó una cámara ICCD para captar la quimioluminiscencia emitida por los radicales presentes en la llama y así definir el frente de llama. La velocidad de deflagración fue calculada empleando el método del cono. Los resultados experimentales fueron comparados con los reportados por otros autores y simulaciones numéricas realizadas con software CHEMKIN empleando el mecanismo GRIMECH 3.0. En este trabajo se encontró que la disminución de la presión atmosférica de 1013 mbar a 852 mbar genera un incremento del 7% en la velocidad de deflagración laminar. Abstract in english Experimental measurements of laminar flame speed for premixed methane-air flames were carried out for different equivalence ratios at subatmospheric conditions, 852 mbar and 298 K. The flames were obtained using a rectangular port burner with a water cooler system necessary to maintain the temperatu [...] re of the mixture constant. An ICCD camera was used to capture chemiluminescence emitted by OH-CH radicals present in the flame and thus define the flame front. Laminar flame speed was calculated using the cone method and experimental results were compared with those reported by other authors and the numerical simulations made with the software CHEMKIN using the GRIMECH 3.0 mechanism. In this work it was found that decreasing the barometric pressure from 1013 mbar to 852 mbar generated an increase of 7% in the laminar flame speed.

  13. Blood pressure measurement

    Science.gov (United States)

    Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure ... or your health care provider will wrap the blood pressure cuff snugly around your upper arm. The ...

  14. Integral analysis of cavity pressurization in a fuel rod during an ULOF driven TOP with inclusion of surface tension effects on froth gas bubbles and variable cavity conditions due to fuel melting and ejection

    International Nuclear Information System (INIS)

    The transient cavity pressurization in an ULOF driven TOP excursion has been analyzed for the SPX-1 reactor with an equation of state that allows to simulate the contribution of small froth gas bubbles to the pressure build-up in a fuel pin with inclusion of restraints from surface tension. Calculations were performed for various bubble parameters. Estimates are made for effective gas availabilities at fuel melting which can be used in a cavity model with an ideal gas equation to arrive at similar pressure transients

  15. On pressure change occurring during gas mixing

    International Nuclear Information System (INIS)

    A pressure change results at thermal equilibrium when ideal gases initially having the same pressure, different temperature, and dissimilar molecular structure are mixed in a constant volume isolated reservoir. This pressure change does not arise from the gas mixing, but rather it results from a redistribution of energy between the translational and internal molecular motion. The conditions for the existence of an extremum in the pressure change are also given

  16. Pressure Induced Fermi Surface Deformation in Lithium

    OpenAIRE

    Rodriguez-prieto, A.; Bergara, A.

    2005-01-01

    Recently reported structural complexity and superconducting transition in lithium under pressure has increased the interest in light alkalis, otherwise considered as simple metals and well known systems under normal conditions. In this work we present an analysis of the pressure induced Fermi surface deformation in lithium with increasing pressure. According to our calculations, under pressure the Fermi surface becomes highly anisotropic and around 30 GPa develops an extende...

  17. Baseline estimate of the retained gas volume in Tank 241-C-106

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, C.W.; Chen, G.

    1998-06-01

    This report presents the results of a study of the retained gas volume in Hanford Tank 241-C-106 (C-106) using the barometric pressure effect method. This estimate is required to establish the baseline conditions for sluicing the waste from C-106 into AY-102, scheduled to begin in the fall of 1998. The barometric pressure effect model is described, and the data reduction and detrending techniques are detailed. Based on the response of the waste level to the larger barometric pressure swings that occurred between October 27, 1997, and March 4, 1998, the best estimate and conservative (99% confidence) retained gas volumes in C-106 are 24 scm (840 scf) and 50 scm (1,770 scf), respectively. This is equivalent to average void fractions of 0.025 and 0.053, respectively.

  18. Blade Tip Pressure Measurements Using Pressure Sensitive Paint

    Science.gov (United States)

    Wong, Oliver D.; Watkins, Anthony Neal; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.

  19. Pressure transient in liquid lines

    International Nuclear Information System (INIS)

    The pressure surge that results from a step change of flow in liquid pipelines, commonly known as water hammer, was analyzed by an eigenfunction method. A differential-integral Pressure wave equation and a linearized velocity equation were derived from the equations of mass and momentum conservation. Waveform distortion due to viscous dissipation and pipe-wall elastic expansion is characterized by a dimensionless transmission number K. The pressure surge condition, which is mathematically singular, was used in the solution procedure. The exact solutions from numerical calculation of the differential-integral equation provide a complete Pressure transient in the pipe. The problems