WorldWideScience

Sample records for barometric pressure conditions

  1. 14 CFR 91.144 - Temporary restriction on flight operations during abnormally high barometric pressure conditions.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Temporary restriction on flight operations during abnormally high barometric pressure conditions. 91.144 Section 91.144 Aeronautics and Space... paragraph (a) of this section to permit emergency supply, transport, or medical services to be delivered...

  2. NOAA NOS SOS, EXPERIMENTAL - Barometric Pressure

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA NOS SOS server is part of the IOOS DIF SOS Project. The stations in this dataset have barometric pressure data. *These services are for testing and...

  3. New insights from well responses to fluctuations in barometric pressure

    Science.gov (United States)

    Butler, J.J.; Jin, W.; Mohammed, G.A.; Reboulet, E.C.

    2011-01-01

    Hydrologists have long recognized that changes in barometric pressure can produce changes in water levels in wells. The barometric response function (BRF) has proven to be an effective means to characterize this relationship; we show here how it can also be utilized to glean valuable insights into semi-confined aquifer systems. The form of the BRF indicates the degree of aquifer confinement, while a comparison of BRFs between wells sheds light on hydrostratigraphic continuity. A new approach for estimating hydraulic properties of aquitards from BRFs has been developed and verified. The BRF is not an invariant characteristic of a well; in unconfined or semi-confined aquifers, it can change with conditions in the vadose zone. Field data from a long-term research site demonstrate the hydrostratigraphic insights that can be gained from monitoring water levels and barometric pressure. Such insights should be of value for a wide range of practical applications. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

  4. NOS CO-OPS Meteorological Data, Barometric Pressure, 6-Minute

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has Barometric Pressure data from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). WARNING: These preliminary data have...

  5. 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.

  6. 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

  7. Water-Level Responses to Barometric-Pressure Fluctuations in Wells in Semi-Confined Aquifers

    Science.gov (United States)

    Jin, W.; Butler, J. J.

    2009-12-01

    Hydrologists have long recognized that changes in barometric pressure can produce changes in water levels in wells. The relationship between barometric pressure and water level has traditionally been characterized using the barometric efficiency (BE), the ratio of the change in water level to the change in barometric pressure head. Although BE has proven to be an effective means of characterizing the short-term response of a well to a change in barometric pressure, the barometric response function (BRF) is a more effective means to characterize the longer-term response. The BRF, which can be determined through a regression deconvolution procedure developed by Rasmussen and co-workers (Rasmussen and Crawford, 1997; Toll and Rasmussen, 2007), characterizes the water level response over time to a step change in barometric pressure, essentially BE as a function of the time since the imposed load. We have extended earlier work of Rasmussen and Spane (Rasmussen and Crawford, 1997; Spane, 2002) to show that the BRF can be utilized to glean important insights into semi-confined aquifer systems. The form of the BRF indicates the degree of aquifer confinement, while a comparison of BRFs from different wells provides insight into aquitard continuity. Recently, we have developed a new approach for estimating aquitard K by fitting type curves to experimentally determined BRFs. We will demonstrate the power of the BRF using field data from a long-term monitoring site of the Kansas Geological Survey at which a four-day pumping test has previously been performed. The aquitard K estimates obtained from the BRFs are in good agreement at this site with the estimate determined from the pumping test. We will also show how the BRF for a well in a semi-confined aquifer can be used to gain insights into conditions in the overlying unconfined aquifer and vadose zone. Although the BE is considered an invariant parameter of a well, we will show that the BRF of a well in a semi

  8. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, Barometric (Air) Pressure

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Barometric (Air) Pressure data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  9. TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, Barometric (Air) Pressure

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Barometric (Air) Pressure data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  10. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, Barometric (Air) Pressure

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Barometric (Air) Pressure data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  11. TAO/TRITON, RAMA, and PIRATA Buoys, 5-Day, Barometric (Air) Pressure

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has 5-day Barometric (Air) Pressure data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  12. 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

  13. 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)

  14. Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yu-Shu; Zhang, Keni; Liu, Hui-Hai

    2005-05-17

    We present a three-dimensional modeling study of gas flow inthe unsaturated fractured rock of Yucca Mountain. Our objective is toestimate large-scale fracture permeability, using the changes insubsurface pneumatic pressure in response to barometric pressure changesat the land surface. We incorporate the field-measured pneumatic datainto a multiphase flow model for describing the coupled processes ofliquid and gas flow under ambient geothermal conditions. Comparison offield-measured pneumatic data with model-predicted gas pressures is foundto be a powerful technique for estimating the fracture permeability ofthe unsaturated fractured rock, which is otherwise extremely difficult todetermine on the large scales of interest. In addition, this studydemonstrates that the multi-dimensional-flow effect on estimatedpermeability values is significant and should be included whendetermining fracture permeability in heterogeneous fracturedmedia.

  15. [The influence of barometric pressure changes in the oral cavity: dental barotrauma and barodontalgia].

    Science.gov (United States)

    Nakdimon, I; Zehavi, E; Chapnik, L; Zadik, Y

    2014-07-01

    Several oro-facial physiologic and pathologic phenomena affect individuals during flight or self-contained underwater breathing apparatus (SCUBA) diving. Physicians and dentists who treat aircrews and divers are occasionally challenged by those manifestations, though their uncommon appearance. This article reviews the two main barometric-related phenomena in the oral cavity: dental barotrauma and barodontalgia. Dental barotrauma includes all barometric-related dental mechanical phenomena. Tooth fracture or failure of dental restoration usually appears in a tooth with a leaking restoration or secondary caries lesion. In addition, changes in barometric pressure can cause a reduction in the retention of dental restoration and appliance. Barodontalgia is the oral pain which evoked during changes of the atmospheric pressure. This manifestation can be classified as a direct or non-direct pain. In most cases, the direct pain is caused by deterioration of pre-existed oral disease, whereas the source of the nondirect pain is an extra-oral facial barotrauma. These two barometric-related manifestations can cause a decrease in life quality and jeopardize the safety of flight or diving.

  16. 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...

  17. Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

    Science.gov (United States)

    Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

    1996-01-01

    Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

  18. Earthquake Weather: Linking Seismicity to Changes in Barometric Pressure, Earth Tides, and Rainfall

    Science.gov (United States)

    West, J. D.; Garnero, E.; Shirzaei, M.

    2015-12-01

    It has been widely observed that earthquakes can be triggered due to changes in stress induced by the passage of surface waves from remote earthquakes. These stress changes are typically on the order of a few kiloPascals and occur over time spans of seconds. Less well investigated is the question of whether triggering of seismic activity can result from similar stress changes occurring over periods of hours or days due to changing barometric pressure, rainfall, and Earth tides. Past studies have shown a possible link between these stress sources and slow earthquakes in Taiwan (Hsu et al., 2015). Here, we investigate the relationship between seismicity and changing barometric pressure, Earth tides, and rainfall for four regions of the western United States where regional seismic networks provide high-quality seismic catalogs over relatively long time periods: Southern California, Northern California, the Pacific Northwest, and Utah. For each region we obtained seismic catalogs from January 2001 through September 2014 and acquired hourly data for barometric pressure and rainfall across the regions from the National Climatic Data Center. The vertical stress time series due to Earth tides was computed for the location of each weather station in the study areas. We summed the stresses from these 3 sources and looked for variations in seismicity correlated to the stress changes. We show that seismicity rates increase with increasing magnitude of stress change. In many cases the increase in seismicity is larger for reductions in vertical stress than it is for stress increases. We speculate that the dependency of seismic rate on combined vertical stress is acting through a combination of two mechanisms: (1) Reduced stresses reduce the normal force on faults, triggering failure in critically-stressed faults. (2) Increased stresses may similarly reduce the normal force on faults due to increases in pore pressure induced in the fault region.

  19. Energy expenditure estimation during normal ambulation using triaxial accelerometry and barometric pressure

    International Nuclear Information System (INIS)

    Energy expenditure (EE) is an important parameter in the assessment of physical activity. Most reliable techniques for EE estimation are too impractical for deployment in unsupervised free-living environments; those which do prove practical for unsupervised use often poorly estimate EE when the subject is working to change their altitude by walking up or down stairs or inclines. This study evaluates the augmentation of a standard triaxial accelerometry waist-worn wearable sensor with a barometric pressure sensor (as a surrogate measure for altitude) to improve EE estimates, particularly when the subject is ascending or descending stairs. Using a number of features extracted from the accelerometry and barometric pressure signals, a state space model is trained for EE estimation. An activity classification algorithm is also presented, and this activity classification output is also investigated as a model input parameter when estimating EE. This EE estimation model is compared against a similar model which solely utilizes accelerometry-derived features. A protocol (comprising lying, sitting, standing, walking, walking up stairs, walking down stairs and transitioning between activities) was performed by 13 healthy volunteers (8 males and 5 females; age: 23.8 ± 3.7 years; weight: 70.5 ± 14.9 kg), whose instantaneous oxygen uptake was measured by means of an indirect calorimetry system (K4b2, COSMED, Italy). Activity classification improves from 81.65% to 90.91% when including barometric pressure information; when analyzing walking activities alone the accuracy increases from 70.23% to 98.54%. Using features derived from both accelerometry and barometry signals, combined with features relating to the activity classification in a state space model, resulted in a .VO2 estimation bias of −0.00 095 and precision (1.96SD) of 3.54 ml min−1 kg−1. Using only accelerometry features gives a relatively worse performance, with a bias of −0.09 and precision (1.96SD) of 5

  20. Spurious barometric pressure acceleration in Antarctica and propagation into GRACE Antarctic mass change estimates

    Science.gov (United States)

    Kim, Byeong-Hoon; Eom, Jooyoung; Seo, Ki-Weon; Wilson, Clark R.

    2016-08-01

    Apparent acceleration in Gravity Recovery and Climate Experiment (GRACE) Antarctic ice mass time-series may reflect both ice discharge and surface mass balance contributions. However, a recent study suggests there is also contamination from errors in atmospheric pressure de-aliasing fields [European Center for Medium-Range Weather Forecast (ECMWF) operational products] used during GRACE data processing. To further examine this question, we compare GRACE atmospheric pressure de-aliasing (GAA) fields with in situ surface pressure data from coastal and inland stations. Differences between the two are likely due to GAA errors, and provide a measure of error in GRACE solutions. Time-series of differences at individual weather stations are fit to four presumed error components: annual sinusoids, a linear trend, an acceleration term and jumps at times of known ECMWF model changes. Using data from inland stations, we estimate that atmospheric pressure error causes an acceleration error of about +7.0 Gt yr-2, which is large relative to prior GRACE estimates of Antarctic ice mass acceleration in the range of -12 to -14 Gt yr-2. We also estimate apparent acceleration rates from other barometric pressure (reanalysis) fields, including ERA-Interim, MERRA and NCEP/DOE. When integrated over East Antarctica, the four mass acceleration estimates (from GAA and the three reanalysis fields) vary considerably (by ˜2-16 Gt yr-2). This shows the need for further effort to improve atmospheric mass estimates in this region of sparse in situ observations, in order to use GRACE observations to measure ice mass acceleration and related sea level change.

  1. Barometric pressure, conductivity, temperature, and water level data from tide gauge from the Florida Department of Environmental Protection Tide Station from 01 January 1977 to 31 December 1999 (NODC Accession 0000358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Barometric pressure, conductivity, temperature, and water level data were collected at fixed platforms in the North Atlantic Ocean and Coastal waters of Florida...

  2. Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data

    Energy Technology Data Exchange (ETDEWEB)

    FA Spane, Jr.

    1999-12-16

    The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate barometric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.

  3. Barometric altimetry system as virtual constellation applied in CAPS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This work describes the barometric altimetry as virtual constellation applied to the Chinese Area Positioning System (CAPS), which uses the transponders of communication satellites to transfer navigation messages to users. Barometric altimetry depends on the relationship of air pressure varying with altitude in the Earth’s atmosphere. Once the air pressure at a location is measured the site altitude can be found. This method is able to enhance and improve the availability of three-dimensional positioning. The difficulty is that the relation between barometric pressure and altitude is variable in different areas and under various weather conditions. Hence, in order to obtain higher accuracy, we need to acquire the real-time air pressure corresponding to an altimetric region’s reference height. On the other hand, the altimetry method will be applied to satellite navigation system, but the greatest difficulty lies in how to get the real-time air pressure value at the reference height in the broad areas overlaid by satellite navigation. We propose an innovational method to solve this problem. It is to collect the real-time air pressures and temperatures of the 1860 known-altitude weather observatories over China and around via satellite communication and to carry out time extrapolation forecast uniformly. To reduce data quantity, we first partition the data and encode them and then broadcast these information via navigation message to CAPS users’ receivers. Upon the interpolations being done in receivers, the reference air pressure and temperature at the receiver’s nearby place is derived. Lastly, combing with the receiver-observed real air pressure and temperature, the site’s altitude can be determined. The work is presented in the following aspects: the calculation principle, formulae, data collection, encoding, prediction, interpolation method, navigation message transmission together with errors causes and analyses. The advantages and shortcomings of the

  4. Barometric altimetry system as virtual constellation applied in CAPS

    Institute of Scientific and Technical Information of China (English)

    AI GuoXiang; SHENG PeiXuan; DU JinLin; ZHENG YongGuang; CAI XianDe; WU HaiTao; HU YongHui; HUA Yu; LI XiaoHui

    2009-01-01

    This work describes the barometric altimetry as virtual constellation applied to the Chinese Area Positioning System (CAPS),which uses the transponders of communication satellites to transfer navigation messages to users.Barometric altimetry depends on the relationship of air pressure varying with altitude in the Earth's atmosphere.Once the air pressure at a location is measured the site altitude can be found.This method is able to enhance and improve the availability of three-dimensional positioning.The difficulty is that the relation between barometric pressure and altitude is variable in different areas and under various weather conditions.Hence,in order to obtain higher accuracy,we need to acquire the real-time air pressure corresponding to an altimetric region's reference height.On the other hand,the altimetry method will be applied to satellite navigation system,but the greatest difficulty lies in how to get the real-time air pressure value at the reference height in the broad areas overlaid by satellite navigation.We propose an innovational method to solve this problem.It is to collect the real-time air pressures and temperatures of the 1860 known-altitude weather observatories over China and around via satellite communication and to carry out time extrapolation forecast uniformly.To reduce data quantity,we first partition the data and encode them and then broadcast these information via navigation message to CAPS users' receivers.Upon the interpolations being done in receivers,the reference air pressure and temperature at the receiver's nearby place is derived.Lastly,combing with the receiver-observed real air pressure and temperature,the site's altitude can be determined.The work is presented in the following aspects:the calculation principle,formulae,data collection,encoding,prediction,interpolation method,navigation message transmission together with errors causes and analyses.The advantages and shortcomings of the technique are discussed at the end.

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

    DEFF Research Database (Denmark)

    Özkil, Ali Gürcan; Fan, Zhun; Xiao, Jizhong;

    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....

  6. BETCO: A Computer Program for the Removal of Barometric and Earth Tide Effects From Water Levels

    Science.gov (United States)

    Toll, N.; Rasmussen, T. C.

    2005-12-01

    Barometric pressure effects in long-term water level measurements can mask drawdown responses to well tests and natural stimuli. Noise caused by barometric pressure and earth tide effects complicates analysis of pressure response data using diagnostic pressure derivative plots. A computer program has been developed to remove fluctuations in groundwater levels induced by changes in barometric pressure and earth tides. The program implements a regression deconvolution method to obtain a barometric response function and remove the barometric pressure and earth tide effects from the groundwater level data. Using the barometric response function yields a better residual or corrected head than using a constant barometric efficiency. The graphical response function can be used to diagnose aquifer type and well skin effects. A modification of the regression deconvolution has been implemented to simultaneously remove earth tide effects as well as barometric effects on water levels. The removal of the earth tide effects is provided as a beta feature. The software has been applied to 13 water level data sets at the Waste Isolation Pilot Plant in Carlsbad, NM. The results are compared to a constant barometric efficiency correction method. The freeware software is available as an install wizard for Windows XP and 2000. As of submission, all results output from BETCO are considered preliminary, please do not cite. The code is under continued development and will be qualified per the Sandia National Laboratories WIPP Software QA Plan requirements. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S. Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  7. 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.

  8. 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

  9. 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

  10. 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…

  11. 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.

  12. Detecting the vulnerability of groundwater in semi-confined aquifers using barometric response functions

    Science.gov (United States)

    Odling, N. E.; Perulero Serrano, R.; Hussein, M. E. A.; Riva, M.; Guadagnini, A.

    2015-01-01

    The use of barometric response functions (BRFs) for detecting the presence of fully penetrating, highly conductive bodies within aquifer confining layers that present potential pathways for contaminants is explored. BRFs are determined from borehole water level (WL) and barometric pressure (Bp) records. Past studies have shown that confining layer properties can be estimated from BRFs, providing a potential link between BRFs and the concept of groundwater vulnerability. Existing analytical models that predict the BRF from system properties assume homogeneity within the aquifer and its confining layer, conditions which are seldom satisfied in nature. The impact of partially and fully penetrating, high diffusivity heterogeneities within a confining layer (representing potential high flow pathways for contaminants) on the BRF is investigated through a suite of three-dimensional, transient numerical simulations of the confining layer-aquifer system. The results are interpreted through comparison with a modified pre-existing analytical model for the BRF. Comparison of numerically and analytically calculated BRFs reveals that the key effect of a localised, fully penetrating, high diffusivity heterogeneity within a low diffusivity confining layer is to reduce the BRF gain with only minor changes to the phase. This impact on the BRF decreases with increasing distance from the heterogeneity. The importance of heterogeneity size is secondary to distance from the borehole and partially penetrating heterogeneities affect the BRF to only a minor extent. Data from a study of the Chalk Aquifer (E. Yorkshire, England) which is semi-confined by heterogeneous glacial sediments display variations in BRFs which are qualitatively similar to those shown by the numerical results. It is suggested that the variation in BRFs estimated from borehole records across a semi-confined aquifer could be used to assess the degree of spatial continuity of low diffusivity lithologies within the

  13. Modeling solidification structure evolution and microsegregation under pressure condition

    Institute of Scientific and Technical Information of China (English)

    Qiang Li; Qiaoyi Guo; Rongde Li

    2006-01-01

    Solidification microstructure and microsegregation were simulated under a constant pressure condition using the cellular automaton method. First, a single dendrite evolution was simulated and compared under pressure condition and under normal condition,respectively. The solidification microstructure and microsegregation were then simulated. Through simulation, it may be concluded that if the growth direction of the dendrite is parallel to the pressure direction, dendrite growth will be hindered. On the other hand,pressure has no influence on the dendrite evolution. However, when two dendrites grow in close contact, solute enrichment occurs in the dendrites, which hinders the growth of the dendrites. In addition, the solute is preferentially enriched along the pressure direction.

  14. Character of water or barometric pressure jump within karst conduit in large strong drainage area of karst water filling mine in Dachengqiao,Ningxiang,Hunan%湖南宁乡大成桥充水矿山疏干区岩溶系统水气压力监测及突变特征

    Institute of Scientific and Technical Information of China (English)

    蒋小珍; 雷明堂; 管振德

    2016-01-01

    Meitanba Coal Mine,Hunan Province,is one of the coal mines famous for karst water flooding in China.Its current mining level is about -400 m and the quantity of pumped water from the mine is about 1 1 000 m3 per hour.For long,due to the continuous mine water drainage a great groundwater depression cone with an area of 21 9.1 9 km2 has been formed.Generally,most sinkholes induced by the mine drainage mainly occur in three stages,which include drainage beginning,groundwater level dropping beneath the bed-rock surface and the occurrence of water inrush incidents,so sinkholes would not be appeared in dewatering zone.But more and more sinkholes have formed in recent years,even though the authorities have taken a se-ries of countermeasures to control these karst hazards.In order to analyze the mechanism of sinkhole forma-tion and help the government make decision,the Dachengqiao region was selected as a pilot site to identify the dynamic source of sinkholes.Data derived from the monitoring of water or barometric pressure within karst conduit show that the fluctuation of barometric pressures in the dewatering zone is extremely signifi-cant with a maximum fluctuation range of 54.72 meters happens in a year and a maximum instant variation velocity of 70.6 cm/min,which is believed to the air blasting and soil collapsing triggered by the sinkhole collapses that create the abrupt jumps of the barometric pressure.%湖南煤炭坝煤矿是我国著名的大水矿山,开采标高已降至-400 m,每小时排水量11000 m3。长期的疏干排水,已形成面积达219.19 km2的地下水降落漏斗。以往的调查资料表明,矿山疏干诱发的岩溶塌陷主要发生在疏干开始、地下水位下降到基岩面附近、矿坑发生突水突泥灾害等3个阶段,在疏干区应该无诱发因素导致岩溶塌陷的发生。但近年来煤炭坝煤矿疏干区大成桥的岩溶塌陷特征表明,尽管相关部门采取了一系列处置措施,但岩溶塌陷仍然频繁

  15. Barometric pumping effect for radon-due neutron flux in underground laboratories

    CERN Document Server

    Stenkin, Yu V; Gromushkin, D M; Shchegolev, O B; Sulakov, V P

    2016-01-01

    It is known that neutron background is a big problem for low-background experiments in underground Laboratories. Our global net of en-detectors sensitive to thermal neutrons includes the detectors running both on the surface and at different depths underground. We present here results obtained with the en-detector of 0.75 m^2 which is running more than 3 years in underground room at a depth of 25 m of water equivalent in Skobeltsyn Institute of Nuclear Physics, Moscow. Spontaneous increases in thermal neutron flux up to a factor of 3 were observed in delayed anti-correlation with barometric pressure. The phenomenon can be explained by a radon barometric pumping effect resulting in similar effect in neutron flux produced in (alpha,n)-reactions by alpha-decays of radon and its daughters in surrounding rock

  16. Barometric response functions from borehole water level records and quantification of aquifer vulnerability

    Science.gov (United States)

    Odling, N. E.; Serrano, R. P.; Hussein, M.; Guadagnini, A.; Riva, M.

    2013-12-01

    In confined and semi-confined aquifers, borehole water levels respond to fluctuations in barometric pressure and this response can be used to estimate the properties of aquifer confining layers. We use this response as indicator of groundwater vulnerability for the semi-confined Chalk aquifer in East Yorkshire, UK. Time series data of borehole water levels are corrected for Earth tides and recharge, and barometric response functions (BRFs) estimated using cross-spectral deconvolution-averaging techniques. The resulting BRFs are fitted using a theoretical model of the BRF gain and phase for a semi-confined aquifer (Rojstaczer, 1988) to obtain confining layer properties. For all of the boreholes, non-zero hydraulic diffusivities for the confining layer were found indicating that the aquifer is semi-confined. A ';characteristic time scale' based on the hydraulic and pneumatic diffusivities of the confining layer is introduced as a measure of the degree of aquifer confinement and therefore groundwater vulnerability. The analytical model assumes that the confining layer and aquifer are homogeneous. However, in nature, confining layers are heterogeneous and groundwater vulnerability dominated by the presence of high diffusivity, high flow pathways through the confining layer to the aquifer. A transient numerical model (MODFLOW) was constructed to test the impact of such heterogeneities on the BRF. In the model, an observed barometric pressure time series is used as a boundary condition applied to the upper surface of the top unit of the model (representing the confining layer) and BRFs determined from the time series of model heads in the bottom unit (representing the aquifer). The results from a numerical model with a homogeneous confining layer were found to accurately reproduce the BRFs from a modified version of the analytical model. The introduction of a localized, high diffusive block in the confining layer was found to modify the BRF, reducing the gain amplitude

  17. Stationary and transient thermal states of barometric pumping in the access pit of an underground quarry.

    Science.gov (United States)

    Perrier, Frédéric; Le Mouël, Jean-Louis

    2016-04-15

    The transition zone between free and underground atmospheres hosts spectacular phenomena, as demonstrated by temperature measurements performed in the 4.6m diameter and 20m deep vertical access pit of an abandoned underground quarry located in Vincennes, near Paris. In summer, a stable stratification of the atmosphere is maintained, with coherent temperature variations associated with atmospheric pressure changes, with a barometric tide S2 larger than 0.1°C peak to peak. When the winter regime of turbulent cold air avalanches is initiated, stratification with pressure induced signals can be restored transiently in the upper part of the pit, while the lower part remains fully mixed and insensitive to pressure variations. The amplitude of the pressure to temperature transfer function increases with frequency below 5×10(-4)Hz, with values at 3×10(-5)Hz varying from 0.1°C·hPa(-1) at the bottom up to 2°C·hPa(-1) towards the top of the pit. These temperature variations are accounted for by cave breathing, which is pressure induced motion of air amplified by the large volume of the quarry. This understanding is supported by a numerical model including advective heat transport, heat diffusion, and heat exchange with the pit walls. Mean lifetime in the pit is of the order of 9 to 13h, and barometric pumping results in an effective ventilation rate of the quarry of the order of 10(-7)s(-1). This study illustrates the important role of barometric pumping in heat and matter transport between atmosphere and lithosphere. The resulting stationary and transient states, revealed in this pit, are probably a general feature of functioning interface systems, and therefore are an important aspect to consider in problems of contaminant transport, or the preservation of precious heritage such as rare ecosystems or painted caves.

  18. Stationary and transient thermal states of barometric pumping in the access pit of an underground quarry.

    Science.gov (United States)

    Perrier, Frédéric; Le Mouël, Jean-Louis

    2016-04-15

    The transition zone between free and underground atmospheres hosts spectacular phenomena, as demonstrated by temperature measurements performed in the 4.6m diameter and 20m deep vertical access pit of an abandoned underground quarry located in Vincennes, near Paris. In summer, a stable stratification of the atmosphere is maintained, with coherent temperature variations associated with atmospheric pressure changes, with a barometric tide S2 larger than 0.1°C peak to peak. When the winter regime of turbulent cold air avalanches is initiated, stratification with pressure induced signals can be restored transiently in the upper part of the pit, while the lower part remains fully mixed and insensitive to pressure variations. The amplitude of the pressure to temperature transfer function increases with frequency below 5×10(-4)Hz, with values at 3×10(-5)Hz varying from 0.1°C·hPa(-1) at the bottom up to 2°C·hPa(-1) towards the top of the pit. These temperature variations are accounted for by cave breathing, which is pressure induced motion of air amplified by the large volume of the quarry. This understanding is supported by a numerical model including advective heat transport, heat diffusion, and heat exchange with the pit walls. Mean lifetime in the pit is of the order of 9 to 13h, and barometric pumping results in an effective ventilation rate of the quarry of the order of 10(-7)s(-1). This study illustrates the important role of barometric pumping in heat and matter transport between atmosphere and lithosphere. The resulting stationary and transient states, revealed in this pit, are probably a general feature of functioning interface systems, and therefore are an important aspect to consider in problems of contaminant transport, or the preservation of precious heritage such as rare ecosystems or painted caves. PMID:26855357

  19. 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.

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

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Eriksen, Gert F.; Christensen, Carsten;

    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...... 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...

  1. 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.)

  2. Ash formation under pressurized pulverized coal combustion conditions

    Science.gov (United States)

    Davila Latorre, Aura Cecilia

    Coal combustion is a source of inorganic particulate matter (ash), which can deposit in boilers and also be emitted into the atmosphere becoming part of ambient fine particulate matter (PM 2.5). In order to decrease coal combustion emissions per unit of power produced, higher efficiency systems have been proposed, including systems operating at elevated pressures. These new operating conditions will affect pollutant formation mechanisms, particularly those associated with the conversion of mineral matter to ash. Ash particle formation mechanisms are particularly sensitive to changes in pressure as they are related to the structure of coal char particles at early stages of combustion. To assess the importance of pressure on ash particle formation, pyrolyzed chars and ash particles from pressurized pulverized combustion of two bituminous and one subbituminous U.S. coals at operating pressures up to 30 atm were studied. Pressure changes the distribution of char particle types, changing the spatial distribution of the minerals during the combustion process and therefore affecting particle formation mechanisms. Chars were examined by Scanning Electron Microscopy (SEM) and classified into two different types (cenospheric and solid) depending on porosity and wall thickness. A correlation for estimating the amount of these cenospheric char particles was then proposed for bituminous coals based on the operating conditions and coal maceral analysis. The ash particle size distribution of the coals combusted at different operating pressures was measured using Computer Controlled Scanning Electron Microscopy (CCSEM). The results of the char characterization and ash particle size distribution measurements were then incorporated into an ash particle formation algorithm that was proposed and implemented. The model predicts ash particle size and composition distributions at elevated pressures under conditions of complete char burnout. Ash predictions were calculated by first

  3. Materials Science under Extreme Conditions of Pressure and Strain Rate

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A; Bazan, G; Bringa, E; Caturla, M; Edwards, M J; Glendinning, S G; Kad, B; Kalantar, D H; Kumar, M; Lasinski, B F; Lorenz, K T; McNaney, J; Meyerhofer, D; Meyers, M A; Pollaine, S M; Reisman, D B; Rowley, D; Schneider, M; Stolken, J; Wark, J; Yaakobi, B

    2003-03-27

    Solid state dynamics experiments at very high pressures (P >> 10 GPa) and strain rates ({var_epsilon} >> 10{sup 5} s{sup -1}) have been demonstrated on high energy laser facilities, albeit over brief intervals of time and small spatial scales. We have developed two methods for driving samples to high pressures (10-100 GPa) at high strain rate (10{sup 6}-10{sup 8} s{sup -1}) in the solid state. One method uses a shockless compression technique, and the other uses multiple staged shocks. These drives are calibrated with VISAR measurements of the resulting compression wave. Deformation mechanisms are inferred under these conditions by characterizing recovered samples. Material strength at high pressures and strain rates is deduced by measuring the reduced growth of material perturbations at a hydrodynamically unstable interface. Microscopic lattice response is determined by time-resolved Bragg diffraction and x-ray absorption spectroscopy (EXAFS). Large-scale simulations, both at the continuum level using constitutive models and at the lattice level using molecular dynamics simulation, are used to interpret these integral experiments. We will review our progress in this new area of laser-based materials science research, then present a vision for carrying these solid-state experiments to much higher pressures, P > 1000 GPa, on the National Ignition Facility (NIF) laser facility.

  4. Photoelectron Spectroscopy under Ambient Pressure and Temperature Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ogletree, D. Frank; Bluhm, Hendrik; Hebenstreit, Eleonore B.; Salmeron, Miquel

    2009-02-27

    We describe the development and applications of novel instrumentation for photoemission spectroscopy of solid or liquid surfaces in the presence of gases under ambient conditions or pressure and temperature. The new instrument overcomes the strong scattering of electrons in gases by the use of an aperture close to the surface followed by a differentially-pumped electrostatic lens system. In addition to the scattering problem, experiments in the presence of condensed water or other liquids require the development of special sample holders to provide localized cooling. We discuss the first two generations of Ambient Pressure PhotoEmission Spectroscopy (APPES) instruments developed at synchrotron light sources (ALS in Berkeley and BESSY in Berlin), with special focus on the Berkeley instruments. Applications to environmental science and catalytic chemical research are illustrated in two examples.

  5. Density and solidiifcation feeding model of vacuum counter-pressure cast aluminum alloy under grade-pressuring conditions

    Institute of Scientific and Technical Information of China (English)

    Qing-song Yan; Huan Yu; Gang Lu; Bo-wen Xiong; Suai Xu

    2016-01-01

    The density of vacuum counter-pressure cast aluminum alloy samples under grade-pressuring condition was studied. The effect of grade pressure difference and time on the density of aluminum aloys was discussed, and the solidiifcation feeding model under grade-pressuring condition was established. The results indicate the grade-pressured solidiifcation feeding ability of vacuum counter-pressure casting mainly depends on grade pressure difference and time. With the increase of grade pressure difference, the density of al the aluminum aloy samples increases, and the trend of change in density from the pouring gate to the top location is first decreasing gradually and then increasing. In addition, in obtaining the maximum density, the optimal grade-pressuring time is different for samples with different wal thicknesses, and the solidiifcation time when the solid volume fraction of aluminum aloy reaches about 0.65 appears to be the optimal beginning time for grade-pressuring.

  6. A stochastic approach to noise modeling for barometric altimeters.

    Science.gov (United States)

    Sabatini, Angelo Maria; Genovese, Vincenzo

    2013-11-18

    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.

  7. The Interface Conditions for Pressures at Oil-water Flood Front in the Porous Media Considering Capillary Pressure

    CERN Document Server

    Peng, Xiaolong; Du, Zhimin

    2016-01-01

    Flood front is the jump interface where fluids distribute discontinuously, whose interface condition is the theoretical basis of a mathematical model of the multiphase flow in porous medium. The conventional interface condition at the jump interface is expressed as the continuous Darcy velocity and fluid pressure (named CPVCM). This paper has inspected it via the studying the water-oil displacement in one dimensional reservoir with considering capillary pressure but ignoring the compressibility and gravity. It is proved theoretically that the total Darcy velocity and total pressure (defined by Antoncev etc.), instead of the Darcy velocities and pressures of water and oil, are continuous at the flood front without considering the compressibility of fluid and porous media. After that, new interface conditions for the pressures and Darcy velocity of each fluid are established, which are collectively named as Jump Pressures and Velocities Conditions Model (JPVCM) because the model has shown the jump pressures and...

  8. Pressurized heavy water reactor fuel behaviour in power ramp conditions

    Science.gov (United States)

    Ionescu, S.; Uţă, O.; Pârvan, M.; Ohâi, D.

    2009-03-01

    In order to check and improve the quality of the Romanian CANDU fuel, an assembly of six CANDU fuel rods has been subjected to a power ramping test in the 14 MW TRIGA reactor at INR. After testing, the fuel rods have been examined in the hot cells using post-irradiation examination (PIE) techniques such as: visual inspection and photography, eddy current testing, profilometry, gamma scanning, fission gas release and analysis, metallography, ceramography, burn-up determination by mass spectrometry, mechanical testing. This paper describes the PIE results from one out of the six fuel rods. The PIE results concerning the integrity, dimensional changes, oxidation, hydriding and mechanical properties of the sheath, the fission-products activity distribution in the fuel column, the pressure, volume and composition of the fission gas, the burn-up, the isotopic composition and structural changes of the fuel enabled the characterization of the behaviour of the Romanian CANDU fuel in power ramping conditions performed in the TRIGA materials testing reactor.

  9. Bridge Pressure Flow Scour at Clear Water Threshold Condition

    Institute of Scientific and Technical Information of China (English)

    GUO Junke; KERENYI Kornel; PAGAN-ORTIZ Jorge E; FLORA Kevin

    2009-01-01

    Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally. The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional; all the measured scour profiles can be described by two similarity equations, where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth; the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge; the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge; and the maximum scour depth decreases with increas-ing sediment size, but increases with deck inundation. The theoretical analysis shows that: bridge scour can be divided into three cases, i.e. downstream unsubmerged, partially submerged, and totally submerged. For downstream unsubmerged flows, the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; for partially and totally submerged flows, the equilibrium maximum scour depth can be described by a scour and an inundation similarity number, which has been confirmed by experiments with two decks and two sediment sizes. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile.

  10. AN APPROXIMATION TO LATERAL EARTH PRESSURES FOR K0 CONDITION

    Directory of Open Access Journals (Sweden)

    M. Arslan TEKİNSOY

    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.

  11. Particle behavior and char burnout mechanisms under pressurized combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, C.M.; Spliethoff, H.; Hein, K.R.G.

    1999-07-01

    Combined cycle systems with coal-fired gas turbines promise highest cycle efficiencies for this fuel. Pressurized pulverized coal combustion, in particular, yields high cycle efficiencies due to the high flue gas temperatures possible. The main problem, however, is to ensure a flue gas clean enough to meet the high gas turbine standards with a dirty fuel like coal. On the one hand, a profound knowledge of the basic chemical and physical processes during fuel conversion under elevated pressures is required whereas on the other hand suitable hot gas cleaning systems need to be developed. The objective of this work was to provide experimental data to enable a detailed description of pressurized coal combustion processes. A series of experiments were performed with two German hvb coals, Ensdorf and Goettelborn, and one German brown coal, Garzweiler, using a semi-technical scale pressurized entrained flow reactor. The parameters varied in the experiments were pressure, gas temperature and bulk gas oxygen concentration. A two-color pyrometer was used for in-situ determination of particle surface temperatures and particle sizes. Flue gas composition was measured and solid residue samples taken and subsequently analyzed. The char burnout reaction rates were determinated varying the parameters pressure, gas temperature and initial oxygen concentration. Variation of residence time was achieved by taking the samples at different points along the reaction zone. The most influential parameters on char burnout reaction rates were found to be oxygen partial pressure and fuel volatile content. With increasing pressure the burn-out reactions are accelerated and are mostly controlled by product desorption and pore diffusion being the limiting processes. The char burnout process is enhanced by a higher fuel volatile content.

  12. 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.)

  13. Characteristics of the stress and barometric seismograms produced by the 2011 Tohoku Earthquake ( M9.0) and vertical movements derived from barometric seismograms

    Science.gov (United States)

    Ishii, Hiroshi; Asai, Yasuhiro

    2016-04-01

    High-quality data concerning the Tohoku Earthquake ( M9.0) on March 11, 2011, were obtained from the deep borehole observation network (maximum depth of 1030 m; epicentral distance of approximately 600 km) of the Tono Research Institute of Earthquake Science. In addition to data acquired via seismometers, stress meters, and strain meters, barometric seismograms were recorded by several barometers that are usually used for weather observations. We examined the characteristics of barometric and stress seismograms and compared them to the data obtained using broadband seismometers, finding a shared feature: large amplitudes and long-period waveforms began with the arrival of surface waves. We also investigated the relationship between vertical movements observed with GPS and barometric variations and discovered that the barometric variations were related to the differential of vertical movements, while the vertical movements corresponded to the integral of barometric variations. All these results demonstrate that vertical movements at observation points can be computed from the barometric variations observed at those points.

  14. 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)

  15. 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.

  16. Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

    Science.gov (United States)

    Pellegrino, Ana Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Nardi, Cristiane; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Bento, José Maurício Simões; McNeil, Jeremy N

    2013-01-01

    Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We

  17. Micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio

    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...

  18. Kinetic study of biomass hydrolysis under high pressure conditions

    OpenAIRE

    Relvas, Frederico Miguel Horta de Albuquerque Moura

    2014-01-01

    This study was focused on the kinetics of lignocellulosic biomass pre-treatment, in particular CO2-assisted autohydrolysis. The temperature was fixed at 180 ºC, varying pressure from 0 (CO2-free autohydrolysis), 20, 35 to 50 bar. For every pressure, a set of isothermal reactions was performed for various reaction times from 0 and 45 minutes. The pre-treatment resulted in a liquid, solid and gas phases, which were analyzed by HPLC. The liquid phase is essentially composed by sugars both in ...

  19. Tribological performance of ashless antiwear additives under extreme pressure conditions

    Science.gov (United States)

    Kim, Bohoon

    Zinc diakyl dithiophosphate (ZDDP) has been used in engine oil for several decades as an antiwear additive. However, ZDDP is the primary source of P, S and Zn in the exhaust, which results in frequent maintenance or replacement of exhaust gas treatment systems. The use of ashless additives is more desirable because of recent environmental regulations. The main goal of this research was to develop a fundamental understanding of how ashless compounds protect the tribological surface in comparison to ZDDP. X-ray absorption near edge structure spectroscopy (XANES) has been performed on tribo and thermal films in order to investigate the chemical properties of films generated from ashless antiwear additives like chemical structure as well as chemical composition. In order to achieve this objective, three approaches were used. First, the relationships between ashless thiophosphates and wear properties under extreme pressure were examined. Ashless antiwear additives properly form their tribofilms on the sliding steel surface, reacting with iron (Fe) which is originated from the substrate. The tribofilms consist of iron phosphates, iron sulfides, and iron sulfates that have lower reduced modulus and hardness compared to tribofilms from ZDDP. However, they are still sufficiently stiff to prevent asperity contact and provide antiwear behavior. In addition, the thickness of protective tribofilms formed with ashless thiophosphates was found to be thicker than the ones formed when ZDDP was used under identical tribological conditions. Secondly, in order to understand the mechanism of tribofilm generation of metal free additives, a fundamental understanding of thermal decomposition of ashless antiwear chemistries and their influence on thermal film formation was derived. The decomposed P- and S- containing products of ZDDP reacted with the metal surface and their own metal cations forming thermal films. In case of metal free dithiophosphates, sulfur species initially formed on

  20. Spherical steel containments of pressurized water reactors under accident conditions

    International Nuclear Information System (INIS)

    The investigations will deal with the mechanical behavior of a free standing spherical containment shell built for the latest type of a German pressurized water reactor. The diameter of the containment shell is 56 m. The wall thickness is 38 mm. The material used is the ferritic steel 15MnNi63. The investigation program includes theoretical as well as experimental activities and concerns four different accidents which are beyond the scope of the common design and licensing practice: containment behavior under quasi-static pressure increase up to containment failure; containment behavior under high transient pressures; containment vibrations due to earthquake loadings (consideration of shell imperfections); containment buckling due to earthquake loadings. First results concerning the containment behavior under quasi-static pressure increase are presented. It turns out that the mechanical failure of the containment shell is controlled by plastic instability. A computer program to describe this problem has been developed and membrane tests to check the computational methods have been carried out. (orig.)

  1. Solid Nitrogen at Extreme Conditions of High Pressure and Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A; Gregoryanz, E

    2004-04-05

    We review the phase diagram of nitrogen in a wide pressure and temperature range. Recent optical and x-ray diffraction studies at pressures up to 300 GPa and temperatures in excess of 1000 K have provided a wealth of information on the transformation of molecular nitrogen to a nonmolecular (polymeric) semiconducting and two new molecular phases. These newly found phases have very large stability (metastability) range. Moreover, two new molecular phases have considerably different orientational order from the previously known phases. In the iota phase (unlike most of other known molecular phases), N{sub 2} molecules are orientationally equivalent. The nitrogen molecules in the theta phase might be associated into larger aggregates, which is in line with theoretical predictions on polyatomic nitrogen.

  2. Estimation of partial pressure during graphite conditioning by matrix method

    International Nuclear Information System (INIS)

    Plasma Facing Components (PFC) of SST-1 tokamak are designed to be compatible for UHV as it is kept in the main vacuum vessel. Graphite is the most widely used plasma facing material in present day tokamaks. High thermal shock resistance and low atomic number carbon are the most important properties of graphite for this application. However, graphite is porous and absorbs gases, which may be released during plasma operation. Graphite tiles are baked at high temperature of about 1000 deg. C in high vacuum (10-5 Torr) for several hours before installing them in the tokamak to remove the impurities (mainly water vapour and metal impurities), which may have been deposited during machining of the tiles. The measurements of the released gas (such as H2, H2O, CO, CO2, Hydrocarbons, etc.) from graphite tiles during baking are accomplished with the help of a Quadrupole Mass Analyzer (QMA). Since, the output of this measurement is a mass spectrum and not the partial pressures of the residual gases, one needs to adopt some procedure to convert the spectrum to obtain the partial pressures. The conventional method of analysis is tedious and time consuming. We propose a new approach based on constructing a set of linear equations and solving them using matrix operations. This is a simple method compared to the conventional one and also eliminates the limitations of the conventional method. A Fortran program has been developed which identifies the likely gases present in the vacuum system and calculates their partial pressures from the data of the residual gas analyzers. Application of this method of calculating partial pressures from mass spectra data will be discussed in detail in this paper

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

    International Nuclear Information System (INIS)

    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. (paper)

  4. Mechanistic modeling of thermal-mechanical deformation of CANDU pressure tube under localized high temperature condition

    International Nuclear Information System (INIS)

    Thermal strain deformation is a pressure tube failure mechanism. The main objective of this paper is to develop mechanistic models to evaluate local thermal-mechanical deformation of a pressure tube in CANDU reactor and to investigate fuel channel integrity under localized contact between fuel elements and pressure tube. The consequence of concern is potential creep strain failure of a pressure tube and calandria tube. The initial focus will be on the case where a fuel rod contacts the pressure tube at full power with highly cooling condition

  5. 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.

  6. Intraoral air pressure and oral air flow under different bleed and bite-block conditions.

    Science.gov (United States)

    Putnam, A H; Shelton, R L; Kastner, C U

    1986-03-01

    Intraoral pressures and oral flows were measured as normal talkers produced /p lambda/ and /si/ under experimental conditions that perturbed the usual aeromechanical production characteristics of the consonants. A translabial pressure-release device was used to bleed off intraoral pressure during /p/. Bite-blocks were used to open the anterior bite artificially during /s/. For /p/, intraoral pressure decreased and translabial air leakage increased as bleed orifice area increased. For /s/, flow increased as the area of sibilant constriction increased, but differential pressure across the /s/ oral constriction did not vary systematically with changes in its area. Flow on postconsonantal vowels /lambda/ and /i/ did not vary systematically across experimental conditions. The data imply that maintenance of perturbed intraoral pressure was more effective when compensatory options included opportunity for increased respiratory drive and structural adjustments at the place of consonant articulation rather than increased respiratory drive alone.

  7. Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions.

    Science.gov (United States)

    Yu, Huiyang; Huang, Jianqiu

    2015-09-08

    In this paper, a pressure sensor for low pressure detection (0.5 kPa-40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance.

  8. Mechanical pressure gages under difficult conditions; Mechanische Druckmessgeraete unter schwierigen Einsatzbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Nieswandt, T. [Wika Alexander Wiegand GmbH und Co. KG, Klingenberg (Germany)

    2008-05-15

    In spite of electronic solutions, mechanical pressure meters still find their place in reliable in-situ process pressure monitoring without external influences. Planners and users often have difficulties selecting the optimum meter for a given application, especially where difficult operating conditions are concerned. The contribution presents a neutral and practical guide. (orig.)

  9. A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit

    Directory of Open Access Journals (Sweden)

    Zong Yao

    2016-06-01

    Full Text Available This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of −50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts, the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor’s output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments.

  10. A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit.

    Science.gov (United States)

    Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Xiong, Jijun

    2016-06-18

    This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of -50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor's output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments.

  11. Correct contractions stationary Navier-Stokes equations and boundary conditions for the setting pressure

    Science.gov (United States)

    Otelbaev, Mukhtarbay; Koshanov, Bakytbek D.

    2016-08-01

    This paper describes the correct narrowing of the Navier-Stokes equations in a stationary three-dimensional cube and clarified the correct formulation of the boundary conditions for the pressure in the environment.

  12. The Pressure Boundary Conditions for the Incompressible Navier—Stokes Equations Computation

    Institute of Scientific and Technical Information of China (English)

    YaosongCHEN; TaoJIANG

    1996-01-01

    This article devotes to the correct formulation of the pressure boundary conditions for the incompressible Navier-Stokes equation and gives the method of integration.The example has been shown for its feasibility.

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

    DEFF Research Database (Denmark)

    Fleming, Robert J.; Henriksen, Mogens; Holbøll, Joachim T.

    1997-01-01

    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......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...

  14. Adsorption mechanism of different coal ranks under variable temperature and pressure conditions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-ling

    2008-01-01

    Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The regularity of the variation in the amounts of adsorption by coals under variable temperature and pressure and 30 ~C isothermal conditions are compared and the adsorption characteristics of coal under the composite effect of temperature and pressure were obtained. The adsorption test and data processing method of coal under variable temperature and pressure are presented and the effect of the mechanism of tempera-ture and pressure on the adsorption capacity of coal has been studied. The research results are of significant importance in the in-vestigation of coalbed methane storage mechanism and for the prediction of the amounts of coalbed methane at various depths.

  15. Pore Water Pressure Response of a Soil Subjected to Traffic Loading under Saturated and Unsaturated Conditions

    Science.gov (United States)

    Cary, Carlos

    This study presents the results of one of the first attempts to characterize the pore water pressure response of soils subjected to traffic loading under saturated and unsaturated conditions. It is widely known that pore water pressure develops within the soil pores as a response to external stimulus. Also, it has been recognized that the development of pores water pressure contributes to the degradation of the resilient modulus of unbound materials. In the last decades several efforts have been directed to model the effect of air and water pore pressures upon resilient modulus. However, none of them consider dynamic variations in pressures but rather are based on equilibrium values corresponding to initial conditions. The measurement of this response is challenging especially in soils under unsaturated conditions. Models are needed not only to overcome testing limitations but also to understand the dynamic behavior of internal pore pressures that under critical conditions may even lead to failure. A testing program was conducted to characterize the pore water pressure response of a low plasticity fine clayey sand subjected to dynamic loading. The bulk stress, initial matric suction and dwelling time parameters were controlled and their effects were analyzed. The results were used to attempt models capable of predicting the accumulated excess pore pressure at any given time during the traffic loading and unloading phases. Important findings regarding the influence of the controlled variables challenge common beliefs. The accumulated excess pore water pressure was found to be higher for unsaturated soil specimens than for saturated soil specimens. The maximum pore water pressure always increased when the high bulk stress level was applied. Higher dwelling time was found to decelerate the accumulation of pore water pressure. In addition, it was found that the higher the dwelling time, the lower the maximum pore water pressure. It was concluded that upon further

  16. Well-conditioning effects on bubblepoint pressure of fluid samples from solution-gas-drive reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C. (Univ. of Tulsa, Tulsa, OK (US)); Peres, A.M.M.; Serra, K.V. (Petrobas (BR)); Macias-Chapa, L. (National Autonomous Univ. of Mexico (MX))

    1990-12-01

    This paper considers the determination of the initial or average reservoir bubblepoint pressure from a fluid sample obtained from a well producing a solution-gas-drive reservoir. It is shown that standard API recommended well-conditioning procedures (rate reductions) for obtaining a single-phase (liquid) bottomhole fluid sample do not always redissolve all free gas. Thus, it is not always possible to obtain a single-phase liquid (oil) bottomhole fluid sample that has a bubblepoint pressure equal to the initial or average reservoir bubblepoint pressure. Moreover, monitoring the producing GOR and bottomhole pressure does not always reliably indicate whether two-phase (oil and gas) or single-phase (oil) flow is prevalent in the near-wellbore region. Contrary to current opinion, it is shown that recombination of surface samples of oil and gas form the producing GOR usually yields reliable estimates of average reservoir bubblepoint pressure.

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

    OpenAIRE

    Khoshnevisana A.; Yoozbashizadeha H.

    2012-01-01

    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 f...

  18. 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, β-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.

  19. 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, β-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.

  20. RELATIONSHIP BETWEEN COMPACTING PRESSURE AND CONDITIONS IN PRESSING CHAMBER DURING BIOMASS PRESSING

    Directory of Open Access Journals (Sweden)

    Peter Križan

    2016-02-01

    Full Text Available In this paper, we will present the impact of the conditions in pressing chambers during the pressing of wooden briquettes. The conditions in pressing chambers can significantly impact the resulting compacting pressure required for the pressing of briquettes. In the introduction, we show which parameters of the pressing chamber during pressing can impact the resulting compacting pressure. The experiment results which are shown in this paper described the detected impact of some important pressing chamber parameters. This experiment aims to detect the pressing chamber length impact and the impact of the way of pressing. By setting the pressing conditions, we will be able to achieve the suitable resulting compacting pressure with respect to the required final briquettes quality.

  1. Phase Transformation of BN Nanoparticles Under High Pressure Low Temperature Conditions

    Science.gov (United States)

    Chen, Z.; Lai, Z. F.; Li, K.; Cui, D. L.; Lun, N.; Wang, Q. L.; Jiang, M. H.

    Phase transformation of BN nanoparticles under high pressure (580~860MPa) and low temperature (270~325°C) hot press conditions was investigated. It was found that the contents of orthorhombic boron nitride (oBN) and cubic boron nitride (cBN) increased with the increase of temperature and the prolonging of hot pressing time under high pressure conditions. At the same time, because of the intergrowth of hBN, oBN and cBN. there are strong interactions among these three phases.

  2. 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.

  3. Computational analysis for prediction of pressure of PWR presurizer undertransient conditions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A computer model has been developed for prediction of the pressure in thepressurizer undertransient conditions. In the model three separate thermodynamic regions which arenot required to be inthermal equilibrium have been considered. The mathematical model derived from the general conservation equations includesall of theimportant thermal-hydraulics phenomena occurring in the pressurizer,i.e., stratificationof the hot water andincoming cold water, bulk flashing and condensation, wall condensation, andinterfacial heat and masstransfer, etc. The bubble rising and rain-out models are developed to describe bulkflashing andcondensation, respectively. To obtain the wall condensation rate, a one-dimensionalheat conductionequation is solved by the pivoting method. The presented model will predict thepressure-time behaviorof a PWR pressurizer during a variety of transients. The results obtained from the proposed mathematical model are in good agreementwithavailable data on the CHASHMA nuclear power plant's pressurizer performance.

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

    OpenAIRE

    Ali Syed Haider; Baheta Aklilu Tesfamichael; Hassan Suhaimi

    2014-01-01

    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 o...

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

    OpenAIRE

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

    2014-01-01

    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 ...

  6. Study on Numerical Simulation of Mold Filling and Solidification Processes under Pressure Conditions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The mold filling and solidification simulation for the high pressure die casting (HPDC) and Iow pressure die casting(LPDC) processes were studied. A mathematical model considering the turbulent flow and heat transfer phenomenonduring the HPDC process has been established and parallel computation technique was used for the mold fillingsimulation of the process. The laminar flow characteristics of the LPDC process were studied and a simplified modelfor the mold filling process of wheel castings has been developed. For the solidification simulation under pressureconditions, the cyclic characteristics and the complicated boundary conditions were considered and techniques toimprove the computational efficiency are discussed. A new criterion for predicting shrinkage porosity of Al alloy underIow pressure condition has been developed in the solidification simulation process.

  7. Power X-ray diffraction under extreme conditions of pressure and temperature

    International Nuclear Information System (INIS)

    An important work has been carried out in the field of X-ray diffraction in obtaining accurate structure information from materials at extreme conditions of pressure and temperature. An experimental set-up combining a diamond-anvil high-pressure cell and a laser-heating technique has been installed at the high-pressure beamline ID30 at the ESRF (Grenoble) to study two major constituents of the Earth's deep interior: MgSiO3 perovskite and iron. Experiments carried out on MgSiO3 perovskite up to 86 GPa and over 2000 K yielded detailed structural information on this compound under these conditions and thus important constraints for the lower mantle mineralogical model, favouring a mixture of perovskite and magnesiowuestite. X-ray diffraction patterns recorded on imaging plates with micro-focused monochromatic radiation revealed a new high-temperature structure of iron above 40 GPa. (au)

  8. 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

  9. 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.

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

    DEFF Research Database (Denmark)

    Habib, Tufail

    2012-01-01

    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...

  11. 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.

  12. 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.

  13. Vibration pore water pressure characteristics of saturated fine sand under partially drained condition

    Institute of Scientific and Technical Information of China (English)

    王炳辉; 陈国兴

    2008-01-01

    Vibration pore water pressure characteristics of saturated fine sand under partially drained condition were investigated through stress-controlled cyclic triaxial tests employed varied fine content of samples and loading frequency. In order to simulate the partially drained condition, one-way drainage for sample was implemented when cyclic loading was applied. The results show that the vibration pore water pressure’s response leads the axial stress and axial strain responses, and is lagged behind or simultaneous with axial strain-rate’s response for all samples in this research. In addition, the satisfactory linear relationship between vibration pore water pressure amplitude and axial strain-rate amplitude is also obtained. It means that the direct cause of vibration pore water pressure generation under partially drained conditions is not the axial stress or axial strain but the axial strain-rate. The lag-phase between pore water pressure and axial strain-rate increases with the increase of the fine content or the loading frequency.

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

    International Nuclear Information System (INIS)

    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.

  15. Probing the local, electronic and magnetic structure of matter under extreme conditions of temperature and pressure

    DEFF Research Database (Denmark)

    Torchio, R.; Boccato, S.; Cerantola, V.;

    2016-01-01

    In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy......-dispersive XAS technique available on the ID24 beamline at the ESRF synchrotron. The examples chosen concern the melting and the liquid structure of 3d metals and alloys under high pressures (HPs) and the observation of temperature-induced spin crossover in FeCO3 at HP....

  16. High-Pressure Minerals in Meteorites: Constraints on Shock Conditions and Duration

    Science.gov (United States)

    Sharp, Thomas G.

    2004-01-01

    The objective of this research was to better understand the conditions and duration of shock metamorphism in meteorites through microstructural and microanalytical characterization of high-pressure minerals. A) Continue to investigate the mineralogy and microstructures of melt-veins in a suite of chondritic samples ranging from shock grades S3 through S6 to determine how the mineral assemblages that crystallize at high-pressure and are related to shock grade. B) Investigate the chemical, mineralogical, and microstructural heterogeneities that occur across melt veins to interpret crystallization histories. C) Use static high-pressure experiments to simulate crystallization of melt veins for mineralogical and textural comparisons with the melt veins of naturally shocked samples. D) Characterize the compositions and defect microstructures of polycrystalline ringwoodite, wadsleyite, majorite, (Mg,Fe)Si03-ilmenite and (Mg,Fe)SiO3-perovskite in S6 samples to understand the mechanisms of phase transformations that occur during shock. These results will combined with kinetic data to constrain the time scales of kinetic processes. E) Investigate the transformations of metastable high-pressure minerals back to low- pressure forms to constrain post-shock temperatures and estimates of the peak shock pressure. Of these objectives, we have obtained publishable data on A, B and D. I am currently doing difficult high-pressure melting and quench experiments on an L chondrite known as Mbale. These experiments will provide additional constraints on the mineral assemblages that are produced during rapid quench of an L chondrite at pressures of 16 to 25 GPa. Results from published or nearly published research is presented below. Lists of theses, dissertations and publications are given below.

  17. Pressure-volume-temperature gauging method experiment using liquid nitrogen under microgravity condition of parabolic flight

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Man Su; Park, Hana; Yoo, Don Gyu; Jeong, Sang Kwon [Cryogenic Engineering Laboratory, Department of Mechanical Engineering, KAIST, Daejeon (Korea, Republic of); Jung, Young Suk [Launcher Systems Development Team, Korea Aerospace Research Institute, Daejeon (Korea, Republic of)

    2014-06-15

    Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid.

  18. Phase State and Saturation Vapor Pressure of Submicron Particles of meso-Erythritol at Ambient Conditions.

    Science.gov (United States)

    Emanuelsson, Eva U; Tschiskale, Morten; Bilde, Merete

    2016-09-15

    meso-Erythritol is a sugar alcohol identified in atmospheric aerosol particles. In this work, evaporation of submicron-sized particles of meso-erythritol was studied in a TDMA system including a laminar flow tube under dry conditions at five temperatures (278-308 K) and ambient pressure. A complex behavior was observed and attributed to the formation of particles of three different phase states: (1) crystalline, (2) subcooled liquid or amorphous, and (3) mixed. With respect to saturation vapor pressure, the subcooled liquid and amorphous states are treated to be the same. The particle phase state was linked to initial particle size and flow tube temperature. Saturation vapor pressures of two phase states attributed to the crystalline and subcooled liquid state respectively are reported. Our results suggest a mass accommodation coefficient close to one for both states. PMID:27525492

  19. Cavitation and primary atomization in real injectors at low injection pressure condition

    Science.gov (United States)

    Dumouchel, Christophe; Leboucher, Nicolas; Lisiecki, Denis

    2013-06-01

    This experimental work investigates the influence of the geometry of GDI devices on primary atomization processes under low injection pressure and reduced back pressure. These pressure conditions ensure cavitating flows and observable atomization processes. Measurements include mass flux, structure velocity from high-speed visualizations and spray characterization with a laser diffraction technique. Super-cavitation regime and cavitation string, which have their own influence on the mass flux, develop independently in different injector regions. These regimes impact the flow pattern in the orifice and the subsequent atomization process. A possible interaction between cavitation string and super-cavitation is found to promote a hydraulic-flip-like regime and to deteriorate atomization quality. As far as the geometry of the injector is concerned, the profile of the orifice inlet and the roughness of the sac volume region are found to be important geometrical characteristics.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bahr, J.; Chari, D.; Puchir, M.; Weismantel, S.

    1982-12-01

    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.

  2. Enhanced optoelectronic property of ZnO under negative pressure condition: a first-principles study

    Science.gov (United States)

    Singh, Santosh; Nath Tripathi, Madhvendra

    2016-08-01

    In contrary to high pressure phases of ZnO, recent experimental evidence suggests that β-BeO type lattice modification of ZnO may be realised under negative pressure condition generated by lattice mismatch or by applying strain. The first-principles calculation based on density functional theory (DFT) is employed to investigate the negative pressure phase β-BeO, and the outcomes of the structural, electronic, and optical properties of this phase are compared with the ambient condition wurtzite B4 phase of ZnO. Our phase transition study shows that the B4 phase transforms into the β-BeO phase around negative pressure of -4 GPa and this new phase retains its structural stability even under more negative pressure. Further, the volume of the β-BeO phase increases resulting in a low-density phase with more anisotropic nature and distorted tetrahedral around Zn (or O) atoms along with (2 + 2) coordination as compared to B4 phase. The electronic structure of low-density β-BeO phase changes significantly, however, the band gaps of both the phases are almost same. The change in electronic structure of β-BeO phase turns into a significant blue shift in lower energy region of optical spectra. Moreover, the smaller effective mass values of charge carriers in β-BeO phase compared to B4 phase indicate high mobilities of charge carriers to attain enhanced conductivity. Further, the analysis of optical properties of β-BeO phase indicate the smaller values of reflectivity and absorption coefficients and consequently an enhanced transmittance value of 90% in visible region of optical spectra. The lower effective masses of charge carriers and enhancement in transmittance makes the low density negative pressure β-BeO phase suitable for achieving enhanced optoelectronic property of ZnO.

  3. Retrofit of heat exchanger networks with pressure recovery of process streams at sub-ambient conditions

    International Nuclear Information System (INIS)

    Highlights: • New mathematical model for heat exchanger networks retrofit with pressure recovery. • Optimal heat and work integration applied to the retrofit of sub-ambient processes. • Streams pressure manipulation is used to enhance heat integration of the system. • Compressors and turbines can act on a coupling shaft and/or as stand-alone equipment. • Use of smaller amount of cold utilities, reducing significantly the operational costs. - Abstract: This paper presents a new mathematical programming model for the retrofit of heat exchanger networks (HENs), wherein the pressure recovery of process streams is conducted to enhance heat integration. Particularly applied to cryogenic processes, HENs retrofit with combined heat and work integration is mainly aimed at reducing the use of expensive cold services. The proposed multi-stage superstructure allows the increment of the existing heat transfer area, as well as the use of new equipment for both heat exchange and pressure manipulation. The pressure recovery of streams is carried out simultaneously with the HEN design, such that the process conditions (streams pressure and temperature) are variables of optimization. The mathematical model is formulated using generalized disjunctive programming (GDP) and is optimized via mixed-integer nonlinear programming (MINLP), through the minimization of the retrofit total annualized cost, considering the turbine and compressor coupling with a helper motor. Three case studies are performed to assess the accuracy of the developed approach, including a real industrial example related to liquefied natural gas (LNG) production. The results show that the pressure recovery of streams is efficient for energy savings and, consequently, for decreasing the HEN retrofit total cost especially in sub-ambient processes

  4. 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.

  5. 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.

  6. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    Science.gov (United States)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-09-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  7. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    Science.gov (United States)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-07-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  8. 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

  9. Feasibility study of tar sands conditioning for earth pressure balance tunnelling

    OpenAIRE

    Martinelli, D; D. Peila; E. Campa

    2015-01-01

    This paper presents the results of laboratory test on the feasibility of soil conditioning for earth pressure balance (EPB) excavation in a tar sand, which is a natural material never studied in this respect. The laboratory test performed is based on a procedure and methods used in previous studies with different types of soils, but for this special complex material, additional tests are also conducted to verify particular properties of the tar sands, such as the tilt test and vane shear test...

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

    DEFF Research Database (Denmark)

    Duggen, Lars; Lopes, Natasha; Willatzen, Morten;

    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...... 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....

  11. Experimental Investigation of Pressure-volume-Temperature Mass Gauging Method Under Microgravity Condition by Parabolic Flight

    Science.gov (United States)

    Seo, Mansu; Park, Hana; Yoo, DonGyu; Jung, Youngsuk; Jeong, Sangkwon

    Gauging the volume or mass of liquid propellant of a rocket vehicle in space is an important issue for its economic feasibility and optimized design of loading mass. Pressure-volume-temperature (PVT) gauging method is one of the most suitable measuring techniques in space due to its simplicity and reliability. This paper presents unique experimental results and analyses of PVT gauging method using liquid nitrogen under microgravity condition by parabolic flight. A vacuum-insulated and cylindrical-shaped liquid nitrogen storage tank with 9.2 L volume is manufactured by observing regulation of parabolic flight. PVT gauging experiments are conducted under low liquid fraction condition from 26% to 32%. Pressure, temperature, and the injected helium mass into the storage tank are measured to obtain the ullage volume by gas state equation. Liquid volume is finally derived by the measured ullage volume and the known total tank volume. Two sets of parabolic flights are conducted and each set is composed of approximately 10 parabolic flights. In the first set of flights, the short initial waiting time (3 ∼ 5 seconds) cannot achieve sufficient thermal equilibrium condition at the beginning. It causes inaccurate gauging results due to insufficient information of the initial helium partial pressure in the tank. The helium injection after 12 second waiting time at microgravity condition with high mass flow rate in the second set of flights achieves successful initial thermal equilibrium states and accurate measurement results of initial helium partial pressure. Liquid volume measurement errors in the second set are within 11%.

  12. An atmospheric pressure flow reactor: Gas phase kinetics and mechanism in tropospheric conditions without wall effects

    Science.gov (United States)

    Koontz, Steven L.; Davis, Dennis D.; Hansen, Merrill

    1988-01-01

    A new type of gas phase flow reactor, designed to permit the study of gas phase reactions near 1 atm of pressure, is described. A general solution to the flow/diffusion/reaction equations describing reactor performance under pseudo-first-order kinetic conditions is presented along with a discussion of critical reactor parameters and reactor limitations. The results of numerical simulations of the reactions of ozone with monomethylhydrazine and hydrazine are discussed, and performance data from a prototype flow reactor are presented.

  13. Influences of Casting Pressure Conditions on the Quality and Properties of a Magnesium Cylinder Head Cover Die Casting

    Institute of Scientific and Technical Information of China (English)

    Wenhui LIU; Yangai LIU; Shoumei XIONG; Baicheng LIU; Y. Matsumoto; M. Murakami

    2005-01-01

    Casting pressure conditions have great influences on the casting defects, such as gas porosity, shrinkage porosity and gas holes. A Mg cylinder head cover die casting was used to experimentally study the influences of casting pressure,the loading time and the piston position of pressure intensification on the variation of pressure and the quality of casting. The results show that casting pressure, the loading time and the piston position of pressure intensification have great influences on the pressure variations in the mold, the quality and performance of casting. The external quality, the density and the tensile strength of casting were improved with the increase of casting pressure and the piston position of pressure intensification and the decrease of the loading time of pressure intensification.

  14. High-pressure behavior of cristobalite under quasi-hydrostatic conditions

    Science.gov (United States)

    Cernok, Ana; Bykova, Elena; Liermann, Hanns-Peter; Dubrovinsky, Leonid

    2014-05-01

    phase transition to cristobalite II near 1.5 GPa and the formation of the X-I phase above 10 GPa, in agreement with previous studies. This high-pressure phase persists up the highest pressures achieved and it is not quenchable - upon decompression it retransforms into a phase with Raman spectra very similar to that of the starting α-cristabolate. Single crystal X-ray diffraction data were collected at Extreme Conditions Beamline P02.2 at Petra III. We confirmed the phase transition to cristobalite II and further above 10 GPa to the phase X-I. Indexing of the diffraction patterns of the phase X-I collected at 17 GPa yields a primitive monoclinic unit cell with a = 6.5899(9) Å, b = 4.0493(6) Å, c = 6.841(8) Å, β = 98.15(3)° and the most likely space groups P21/c or P21/n. A preliminary structure analysis reveals that all Si atoms are octahedrally coordinated at this pressure. Single-crystal X-ray diffraction data from experiments at higher pressures are currently being analyzed.

  15. Experimental investigation of symmetric and asymmetric heating of pressure tube under accident conditions for Indian PHWR

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Ashwini K., E-mail: ashwinikumaryadav@gmail.com [Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee-247667 (India); Majumdar, P., E-mail: pmajum@barc.gov.in [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Kumar, Ravi, E-mail: ravikfme@iitr.ernet.in [Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee-247667 (India); Chatterjee, B., E-mail: barun@barc.gov.in [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Gupta, Akhilesh, E-mail: akhilfme@iitr.ernet.in [Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee-247667 (India); Lele, H.G., E-mail: hglele@barc.gov.in [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Circumferential temperature gradient for asymmetric heat-up was 400 Degree-Sign C. Black-Right-Pointing-Pointer At same pressure ballooning initiates at lower temperature in asymmetrical heat-up. Black-Right-Pointing-Pointer At 1 MPa ballooning initiated at 408 Degree-Sign C and with expansion rate of 0.005 mm/s. Black-Right-Pointing-Pointer At 2 MPa ballooning initiation at 330 Degree-Sign C and with expansion rate of 0.0056 mm/s. Black-Right-Pointing-Pointer For symmetrical heat-up strain rate was 10 times faster than asymmetric heat-up. - Abstract: In pressurized heavy water reactor (PHWR), under postulated scenario of small break Loss of Coolant Accident (LOCA) coincident with the failure of Emergency Core Cooling System (ECCS), a situation may arise under which reduction in mass flow rate of coolant through individual reactor channel can lead to stratified flow. Such stratified flow condition creates partial uncover of fuel bundle, which creates a circumferential temperature gradient over PT. The present investigation has been carried out to study thermo-mechanical behaviour of PT under asymmetric heating conditions for a 220 MWe PHWR. A 19-pin fuel simulator has been developed in which preferential heating of elements could be done by supplying power to the selected pins. The asymmetric heating of PT has been carried out at pressure 2 MPa and 1 MPa, respectively, by supplying power to upper region heating elements thus creating an half filled stratified flow conditions. The temperature difference up to 425 Degree-Sign C has been observed along top to bottom periphery of PT. A comparison is made between thermo-mechanical behaviour of PT under asymmetrical and symmetrical heat-up, expected from a large break LOCA condition. The radial expansion rate during symmetrical heating is found to be much faster as compared to that for asymmetric ballooning of PT at the same internal pressure. Integrity of PT is found to be

  16. Study of the dynamical behavior of the LIBS plasma under conditions of low atmospheric pressure

    Science.gov (United States)

    Jijón, D.; Costa Vera, C.

    2011-09-01

    A new arrangement of 3 Langmuir probes to evaluate the electric potential and estimate the electron temperature in the LIBS plasma is introduced in this work. It consists of three nickel meshes (95% of transparency) on a basis for the sample in a vacuum chamber. The sample (a 50 cents coin) was analyzed at 9 different pressures (0.2, 0.4, 0.6, 0.8, 1, 2, 4, 6, 8 Torr). Measurements were made of the voltage signal induced in the electrodes relative to one another and to the sample. Information about the on-time and the duration of the plasma under the decreased pressure conditions can be extracted from these signals, which could in principle, be also correlated with the velocity of expansion of the plasma and the establishment of thermodynamical equilibrium in the system plasma-background gas. Additionally, we photographed the emitted light by LIBS plasma at maximum extension at different pressures by means of two digital cameras at the right angles to one another and to the laser beam. In each case, the expanded plasma contour was mathematically analyzed. In particular, the area of the plasma plume as recorded with the cameras was found to follow a simple relationship with the background pressure in a way not different from an ideal gas.

  17. Measurements of mixtures with carbon dioxide under supercritical conditions using commercial high pressure equipment

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Luciana L.P.R. de; Rutledge, Luis Augusto Medeiros; Moreno, Eesteban L.; Hovell, Ian; Rajagopal, Krishnaswamy [Universidade Federal do Rio de Janeiro (LATCA-EQ-UFRJ), RJ (Brazil). Escola de Quimica. Lab. de Termodinamica e Cinetica Aplicada

    2012-07-01

    There is a growing interest in studying physical properties of binary and multicomponent fluid mixtures with supercritical carbon dioxide (CO{sub 2}) over an extended range of temperature and pressure. The estimation of properties such as density, viscosity, saturation pressure, compressibility, solubility and surface tension of mixtures is important in design, operation and control as well as optimization of chemical processes especially in extractions, separations, catalytic and enzymatic reactions. The phase behaviour of binary and multicomponent mixtures with supercritical CO{sub 2} is also important in the production and refining of petroleum where mixtures of paraffin, naphthene and aromatics with supercritical fluids are often encountered. Petroleum fluids can present a complex phase behaviour in the presence of CO{sub 2}, where two-phase (VLE and LLE) and three phase regions (VLLE) might occur within ranges of supercritical conditions of temperature and pressure. The objective of this study is to develop an experimental methodology for measuring the phase behaviour of mixtures containing CO{sub 2} in supercritical regions, using commercial high-pressure equipment. (author)

  18. Non-adiabatic pressure loss boundary condition for modelling turbocharger turbine pulsating flow

    International Nuclear Information System (INIS)

    Highlights: • Bespoke non-adiabatic pressure loss boundary for pulse flow turbine modelling. • Predictions show convincing results against experimental and literature data. • Predicted pulse pressure propagation is in good agreement with literature data. • New methodology is time efficient and requires minimal geometrical inputs. - Abstract: This paper presents a simplified methodology of pulse flow turbine modelling, as an alternative over the meanline integrated methodology outlined in previous work, in order to make its application to engine cycle simulation codes much more straight forward. This is enabled through the development of a bespoke non-adiabatic pressure loss boundary to represent the turbine rotor. In this paper, turbocharger turbine pulse flow performance predictions are presented along with a comparison of computation duration against the previously established integrated meanline method. Plots of prediction deviation indicate that the mass flow rate and actual power predictions from both methods are highly comparable and are reasonably close to experimental data. However, the new boundary condition required significantly lower computational time and rotor geometrical inputs. In addition, the pressure wave propagation in this simplified unsteady turbine model at different pulse frequencies has also been found to be in agreement with data from the literature, thereby supporting the confidence in its ability to simulate the wave action encountered in turbine pulse flow operation

  19. Pneumatic burst test under 'upper shelf conditions' of a pressure vessel containing an axial defect

    International Nuclear Information System (INIS)

    In a programme of burst tests carried out in the 1960's on model steel pressure vessels with through thickness axial cracks, pressurised with water, some vessels when tested at temperatures in the upper part of the Charpy transition range underwent intermittent crack propagation. Each jump in crack length was accompanied by a drop in pressure, followed by a further crack extension on again raising the pressure. This behavior became more pronounced at higher temperatures and crack lengths and was suspected to be due to the low compressibility of the pressurising water and bulging of the pressure vessel shell local to the crack. Consequently, Test V15T1 was carried out using gas as the pressurising medium in order to demonstrate unambiguously that unstable crack propagation can continue if the loading is such as to give constant or increasing stress conditions as the crack propagates, even at temperatures corresponding to ''upper shelf'' Charpy values. Analyses of the test are given using two fracture assessment methods. (author)

  20. Reparameterization techniques for generating reservoir descriptions conditioned to variograms and well-test pressure data

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C.; He, N.; Chu, L. [Univ. of Tulsa, OK (United States)] [and others

    1995-12-31

    Recently, we have shown that reservoir descriptions conditioned to multiwell pressure data and univariate and bivariate statistics for permeability and porosity can be obtained by techniques developed from inverse problem theory. The techniques yield estimates of well skin factors and porosity and permeability fields which honor both the spatial statistics and the pressure data. Imbedded in the methodology is the application of the Gauss-Newton method to construct the maximum a posteriori estimate of the reservoir parameters. If one wishes to determine permeability and porosity values at thousands of grid-blocks for use in a reservoir simulator, then inversion of the Hessian matrix at each iteration of the Gauss-Newton procedure becomes computationally expensive. In this work, we present two methods to reparameterize the reservoir model to improve the computational efficiency. The first method uses spectral (eigenvalue/eigenvector) decomposition of the prior model. The second method uses a subspace method to reduce the size of the matrix problem that must be solved at each iteration of the Gauss-Newton method. It is shown that proper implementation of the reparameterization techniques significantly decreases the computational time required to generate realizations of the reservoir model, i.e., the porosity and permeability fields and well skin factors, conditioned to prior information on porosity and permeability and multiwell pressure data.

  1. Nonlinear Creep Model for Deep Rock under High Stress and High Pore Water Pressure Condition

    Directory of Open Access Journals (Sweden)

    Xie Yuanguang

    2016-05-01

    Full Text Available Conventional triaxial compression creep experiments for deep sandstone under high confining pressure and high pore water pressure were carried out, in order to predict the creep response of deep rock under these conditions. A nonlinear viscoelastic-plastic creep constitutive model was proposed based on the experimental results. The theory of component model was used as a basis for the formulation of this model. First, by using mathematical fitting and analogy, a new nonlinear viscous component was introduced based on the properties of the creep curves during the tertiary stage. Second, a timer component to judge whether the creep can get into the tertiary stage was presented. Finally, a nonlinear creep model was proposed. Results showed good agreement between theory curves from the nonlinear creep model and experimental data. This model can be applied to predict deep rock creep responses under high stress and high pore water pressure conditions. Hence, the obtained conclusions in this study are beneficial to deep rock engineering.

  2. Feasibility study of tar sands conditioning for earth pressure balance tunnelling

    Directory of Open Access Journals (Sweden)

    D. Martinelli

    2015-12-01

    Full Text Available This paper presents the results of laboratory test on the feasibility of soil conditioning for earth pressure balance (EPB excavation in a tar sand, which is a natural material never studied in this respect. The laboratory test performed is based on a procedure and methods used in previous studies with different types of soils, but for this special complex material, additional tests are also conducted to verify particular properties of the tar sands, such as the tilt test and vane shear test usually used in cohesive materials, and a direct shear test. The laboratory test proves that the test procedure is applicable also to this type of soil and the conditioned material can be considered suitable for EPB excavations, although it is necessary to use a certain percentage of fine elements (filler to create a material suitable to be mixed with foam. The test results show that the conditioned material fulfils the required standard for an EPB application.

  3. Cryogenic Tunnel Pressure Measurements on a Supercritical Airfoil for Several Shock Buffet Conditions

    Science.gov (United States)

    Bartels, Robert E.; Edwards, John W.

    1997-01-01

    Steady and unsteady experimental data are presented for several fixed geometry conditions from a test in the NASA Langley 0.3-Meter Transonic Cryogenic Tunnel. The purpose of this test was to obtain unsteady data for transonic conditions on a fixed and pitching supercritical airfoil at high Reynolds numbers. Data and brief analyses for several of the fixed geometry test conditions will be presented here. These are at Reynolds numbers from 6 x 10(exp 6) to 35 x 10(exp 6) bases on chord length, and span a limited range of Mach numbers and angles of attack just below and at the onset of shock buffet. Reynolds scaling effects appear in both the steady pressure data and in the onset of shock buffet at Reynolds numbers of 15 x 10(exp 6) and 3O x 10(exp 6) per chord length.

  4. Surgical Space Conditions During Low-Pressure Laparoscopic Cholecystectomy with Deep Versus Moderate Neuromuscular Blockade

    DEFF Research Database (Denmark)

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

    2014-01-01

    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......). 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...

  5. Dynamic response of berea sandstone shock-loaded under dry, wet and water-pressurized conditions

    Energy Technology Data Exchange (ETDEWEB)

    Carney, T C; Hagelberg, C R; Hilt, M; Nellis, W J; Swift, R P

    1999-09-03

    A single-stage light-gas gun was used to perform shock-recovery experiments on Berea sandstone under dry, wet and hydrostatically water-pressurized conditions. The samples were impacted by flyer-plates to achieve stress levels in the range 1.3 to 9.8 GPa. The microstructure of the shocked samples was analyzed using scanning electron microscopy (SEM), laser particle analysis and X-ray computed microtomography (XCMT). The dry samples show strongly fragmented and irregularly fractured quartz grains with a considerably reduced porosity, whereas the wet and water-pressurized specimens show less grain damage and less porosity reduction. During shock compression the water in the pores distributes the stresses and therefore the contact force between the grains is reduced. The interaction between the grains during the shock process was modeled by explicitly treating the grain-pore structure using Smooth Particle Hydrodynamics (SPH) and the Discrete Element Method (DEM).

  6. RANS simulation of cavitation and hull pressure fluctuation for marine propeller operating behind-hull condition

    Science.gov (United States)

    Paik, Kwang-Jun; Park, Hyung-Gil; Seo, Jongsoo

    2013-12-01

    Simulations of cavitation flow and hull pressure fluctuation for a marine propeller operating behind a hull using the unsteady Reynolds-Averaged Navier-Stokes equations (RANS) are presented. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. Simulations are performed in design and ballast draught conditions to study the effect of cavitation number. And two propellers with slightly different geometry are simulated to validate the detectability of the numerical simulation. All simulations are performed using a commercial CFD software FLUENT. Cavitation patterns of the simulations show good agreement with the experimental results carried out in Samsung CAvitation Tunnel (SCAT). The simulation results for the hull pressure fluctuation induced by a propeller are also compared with the experimental results showing good agreement in the tendency and amplitude, especially, for the first blade frequency.

  7. Study of dynamic pressure roadway supporting scheme under condition of thick composite roof

    Institute of Scientific and Technical Information of China (English)

    Wei-Jun WANG; Li-Qiang LUO; Wei-Jian YU; Hai WU; Yan-Si QU

    2013-01-01

    This paper analyzed the strata behaviors of solid-coal roadway,gob-side entry driving and deformation law of surrounding rock in depth under high stress and thick composite roof based on the dynamic pressure roadway as engineering background in Fengcheng mining area,Jiangxi province.The results,both field measurement andnumerical simulation show that gob-side entry driving results the deformation of coal roadway main wall,however,entity-coal roadway driving results deformation of main roof and floor.The maintenance state of gob-side entry driving is better than entity-coal roadway,this situation is relevant to thick composite roof layered and easy collapse characteristics.At the same time,this paper put forward and proved proper dynamic pressure roadway supporting scheme under the surrounding rock condition and stress environment.

  8. Dissolution of borosilicate glasses under repository conditions of pressure and temperature

    International Nuclear Information System (INIS)

    This paper described laboratory experimental work in progress in the UK to examine the mechanisms of fluid buffered interactions of materials at possible repository temperatures and pressures and aims at proposing limiting temperature values for a disposal facility from the geochemist's viewpoint. At present work is concentrated on reconnaissance experiments on dissolution rates of the vitrified waste form and the changes in near-field granite surface chemistry and fissure properties which will have a bearing on nuclide adsorption immediately after release. The major conclusions: in all of the experiments the fluid state remained as liquid since temperatures never exceeded 3740C, under these subcritical conditions pressure decreases dissolution rate; the ability to extrapolate dissolution rate from values of 1000C to about 2000C, together with the maintenance of physical integrity indicate that the glasses studied are likely to be stable and predictable in leach behavior to temperatures well in excess of those currently being considered for disposal; Glass 209 dissolves more slowly over a wide pressure and temperature spectrum than does glass 189, although the latter is easier to fabricate; dissolution rate decreases with increasing time. The principal conclusions of this study so far is that experimental application of realistic repository hydrothermal PT conditions indicate for the first time that current formulations of borosilicate glass would appear to provide for an adequate waste disposal medium which would maintain stability and predictable behavior over a wider pressure and temperature spectrum than previously realized, allowing sme latitude in both pre-disposal storage period and eventual loading at the time of disposal

  9. 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...

  10. Windsock memory COnditioned RAM (CO-RAM) pressure effect: Forced reconnection in the Earth's magnetotail

    Science.gov (United States)

    Vörös, Z.; Facskó, G.; Khodachenko, M.; Honkonen, I.; Janhunen, P.; Palmroth, M.

    2014-08-01

    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 Dungey (1963) 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 nonflux transfer-associated forcing is introduced by a combination of the large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented interplanetary magnetic field (IMF). Using global MHD Grand Unified Magnetosphere Ionosphere Coupling Simulation version 4 simulation results, upstream data from Wind, magnetosheath data from Cluster 1 and distant tail data from the two-probe Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun mission, we show that the simultaneous occurrence of vertical windsock motions of the magnetotail and enhanced solar wind dynamic pressure introduces strong nightside disturbances, including enhanced electric fields and persistent vertical cross-tail shear flows. These perturbations, associated with a stream interaction region in the solar wind, drive MR in the tail during episodes of northward oriented interplanetary magnetic field (IMF). We detect MR indirectly, observing plasmoids in the tail and ground-based signatures of earthward moving fast flows. We also consider the application to solar system planets and close-in exoplanets, where the proposed scenario can elucidate some new aspects of solar/stellar wind-magnetosphere interactions.

  11. A Modelling Framework to Assess the Effect of Pressures on River Abiotic Habitat Conditions and Biota.

    Directory of Open Access Journals (Sweden)

    Jochem Kail

    Full Text Available River biota are affected by global reach-scale pressures, but most approaches for predicting biota of rivers focus on river reach or segment scale processes and habitats. Moreover, these approaches do not consider long-term morphological changes that affect habitat conditions. In this study, a modelling framework was further developed and tested to assess the effect of pressures at different spatial scales on reach-scale habitat conditions and biota. Ecohydrological and 1D hydrodynamic models were used to predict discharge and water quality at the catchment scale and the resulting water level at the downstream end of a study reach. Long-term reach morphology was modelled using empirical regime equations, meander migration and 2D morphodynamic models. The respective flow and substrate conditions in the study reach were predicted using a 2D hydrodynamic model, and the suitability of these habitats was assessed with novel habitat models. In addition, dispersal models for fish and macroinvertebrates were developed to assess the re-colonization potential and to finally compare habitat suitability and the availability/ability of species to colonize these habitats. Applicability was tested and model performance was assessed by comparing observed and predicted conditions in the lowland Treene River in northern Germany. Technically, it was possible to link the different models, but future applications would benefit from the development of open source software for all modelling steps to enable fully automated model runs. Future research needs concern the physical modelling of long-term morphodynamics, feedback of biota (e.g., macrophytes on abiotic habitat conditions, species interactions, and empirical data on the hydraulic habitat suitability and dispersal abilities of macroinvertebrates. The modelling framework is flexible and allows for including additional models and investigating different research and management questions, e.g., in climate impact

  12. 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

  13. Traumatic lung injury attributed to tornadic activity-induced barometric pressure changes in two dogs.

    Science.gov (United States)

    Cichocki, Brandy N; Dugat, Danielle R; Snider, Timothy A

    2016-06-01

    CASE DESCRIPTION A 7-year-old castrated male Italian Greyhound (dog 1) and an approximately 1-year-old female Labrador Retriever (dog 2) were evaluated because of respiratory distress 8 and 10 days, respectively, after a tornado. CLINICAL FINDINGS No obvious external injuries were identified auscultation revealed decreased bronchovesicular sounds in the affected hemithorax of both dogs. Clinicopathologic changes were mild, with evidence of inflammation in both dogs. Thoracic radiography of both dogs revealed pneumothorax and pleural effusion with effacement of the diaphragm; findings on CT included severe pulmonary atelectasis of affected lung lobes with normal bronchial tree configurtion and no evidence of diaphragmatic hernia. TREATMENT AND OUTCOME Exploratory thoracotomy of both dogs confirmed CT findings Pulmonary parenchymal damage consistent with a large rupture was found in both patients. A large hematoma was adhered to the ruptured lung lobe of dog 1. Grossly affected lung tissue was removed; histologic examination revealed atelectasis, pulmonary fib osis, thrombosis, and minimal (dog 1) to marked (dog 2) inflammation Microbial culture of lung tissue yielded no growth for dog 1 and Streptococcus spp and Escherichia coli susceptible to amoxicillin-clavulanic acid for dog 2. Dog 1 had a recurrence of pneumothorax treated by drainage with a thoracostomy tube 1 month after surgery. Eighteen months after surgery, both dogs were reportedly doing well. CLINICAL RELEVANCE Development of clinical signs after a tornado, together with clinical, diagnostic imaging, surgical, and histologic findings led to a presumptive diagnosis of pulmonary barotrauma for both dogs. Long-term outcome for these dogs, treated at a referral hospital, was good. PMID:27172344

  14. Linking Metabolism, Elemental Cycles, and Environmental Conditions in the Deep Biosphere: Growth of a Model Extremophile, Archaeoglobus fulgidus, Under High-Pressure Conditions

    Science.gov (United States)

    Oliver, G. C. M.; Cario, A.; Rogers, K. L.

    2015-12-01

    A majority of Earth's biosphere is hosted in subsurface environments where global-scale biogeochemical and energy cycles are driven by diverse microbial communities that operate on and are influenced by micro-scale environmental variables. While the subsurface hosts a variety of geochemical and geothermal conditions, elevated pressures are common to all subsurface ecosystems. Understanding how microbes adapt to and thrive in high-pressure environments is essential to linking microbial subsurface processes with global-scale cycles. Here we are using a model extremophile, Archaeoglobus fulgidus, to determine how elevated pressures affect the growth, metabolism, and physiology of subsurface microorganisms. A. fulgidus cycles carbon and sulfur via heterotrophic and autotrophic sulfate reduction in various high temperature and high-pressure niches including shallow marine vents, deep-sea hydrothermal vents, and deep oil reservoirs. Here we report the results of A. fulgidus growth experiments at optimum temperature, 83°C, and pressures up to 600 bars. Exponential growth was observed over the entire pressure range, though growth rates were diminished at 500 and 600 bars compared to ambient pressure experimental controls. At pressures up to 400 bars, cell density yields and growth rates were at least as high as ambient pressure controls. Elevated pressures and extended incubation times stimulated cell flocculation, a common stress response in this strain, and cellular morphology was affected at pressures exceeding 400 bars. These results suggest that A. fulgidus continues carbon, sulfur and energy cycling unaffected by elevated pressures up to 400 bars, representing a variety of subsurface environments. The ability of subsurface organisms to drive biogeochemical cycles at elevated pressures is a critical link between the surface and subsurface biospheres and understanding how species-scale processes operate under these conditions is a vital part of global

  15. Numerical Study of Pollutant Emissions in a Jet Stirred Reactor under Elevated Pressure Lean Premixed Conditions

    Directory of Open Access Journals (Sweden)

    Karim Mazaheri

    2016-01-01

    Full Text Available Numerical study of pollutant emissions (NO and CO in a Jet Stirred Reactor (JSR combustor for methane oxidation under Elevated Pressure Lean Premixed (EPLP conditions is presented. A Detailed Flow-field Simplified Chemistry (DFSC method, a low computational cost method, is employed for predicting NO and CO concentrations. Reynolds Averaged Navier Stokes (RANS equations with species transport equations are solved. Improved-coefficient five-step global mechanisms derived from a new evolutionary-based approach were taken as combustion kinetics. For modeling turbulent flow field, Reynolds Stress Model (RSM, and for turbulence chemistry interactions, finite rate-Eddy dissipation model are employed. Effects of pressure (3, 6.5 bars and inlet temperature (408–573 K over a range of residence time (1.49–3.97 ms are numerically examined. A good agreement between the numerical and experimental distribution of NO and CO was found. The effect of decreasing the operating pressure on NO generation is much more than the effect of increase in the inlet temperature.

  16. Lorenz-Mie digital holographic microscopy on complex colloids and at extreme pressure conditions (Conference Presentation)

    Science.gov (United States)

    Saglimbeni, Filippo; Bianchi, Silvio; Di Leonardo, Roberto; Padgett, Miles J.; Gibson, Graham; Bowman, Richard W.; Paradossi, Gaio

    2016-03-01

    Lorenz-Mie scattering theory allows to predict the field scattered by spherical objects illuminated by coherent light. By fitting the fringe pattern resulting from the interference of incident and scattered light, it is possible to track and size colloidal particles with a few nanometer precision. Using digital holographic microscopy (DHM) we extend the applications of Lorenz-Mie theory to hollow spherical structures and to extremely high pressure conditions. On the one hand, we geometrically and optically characterize complex colloids as polymer-shelled microbubbles, with high precision, low costs and short acquisition time. These microbubbles are likely to be unique tools for targeted drug delivery and are currently used as contrast agents for sonography. We measured size, shell thickness and refractive index for hundreds of polymeric microbubbles showing that shell thickness displays a large variation that is strongly correlated with its refractive index and thus with its composition. On the other hand we demonstrate that DHM can be used for accurate 3D tracking and sizing of a holographically trapped colloidal probe in a diamond anvil cell (DAC). Polystyrene beads were trapped in water up to Gigapascal pressures while simultaneously recording in-line holograms at 1 KHz frame rate. This technique may potentially provide a new method for spatially resolved pressure measurements inside a DAC.

  17. Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

    2015-01-01

    A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

  18. 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

  19. 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

  20. 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.

  1. First-principles investigation of boron incorporation into CRUD under Pressurized Water Reactor conditions

    Science.gov (United States)

    Rak, Zs.; O'Brien, C. J.; Brenner, D. W.

    2014-03-01

    CRUD (Chalk River Unidentified Deposit) is predominately a nickel-ferrite deposit on hot surfaces of nuclear fuel rods during reactor operation. The presence of CRUD modifies the core-coolant heat transfer and can induce localized corrosion on the cladding surface. Besides these unwanted effects boron, which is a neutron absorber, can accumulate within the CRUD, triggering shifts in the neutron flux and fluctuations in the reactor power level. Therefore, it is crucial to understand and predict the mechanisms by which B is trapped into the CRUD. As a first step, the incorporation of B defect into the crystal structure of NiFe2O4 has been investigated using the DFT framework. To obtain the formation energies of various interstitial and substitutional B-defects, theoretical results have been combined with experimental thermo-chemical data. Assuming solid-solid equilibrium conditions, the main factors that limit the incorporation of B are (i) the narrow stability domain of the host NiFe2O4 and (ii) the formation of ternary Fe-B-O and Ni-B-O compounds. The study also investigates the incorporation of B assuming solid-liquid equilibrium between NiFe2O4 and the surrounding aqueous solution under conditions of pressure, temperature, and pH characteristic to pressurized water reactors.

  2. Thermal response of a modular high temperature reactor during passive cooldown under pressurized and depressurized conditions

    International Nuclear Information System (INIS)

    The concept of inherent safety features of the modular HTR design with respect to passive decay heat removal through conduction, radiation and natural convection was first introduced in the German HTR-module (pebble fuel) design and subsequently extended to other modular HTR design in recent years, e.g. PBMR (pebble fuel), GT-MHR (prismatic fuel) and the new generation reactor V/HTR (prismatic fuel). This paper presents the numerical simulations of the V/HTR using the thermal-hydraulic code THERMIX which was initially developed for the analysis of HTRs with pebble fuels, verified by experiments, subsequently adopted for applications in the HTRs with prismatic fuels and checked against the results of CRP-3 benchmark problem analyzed by various countries with diverse codes. In this paper, the thermal response of the V/HTR (operating inlet/outlet temperatures 490/1000 deg. C) during post shutdown passive cooling under pressurized and depressurized primary system conditions has been investigated. Additional investigations have also been carried out to determine the influence of other inlet/outlet operating temperatures (e.g. 490/850, 350/850 or 350/1000 deg. C) on the maximum fuel and pressure vessel temperature during depressurized cooldown condition. In addition, some sensitivity analyses have also been performed to evaluate the effect of varying the parameters, i.e. decay heat, graphite conductivity, surface emissivity, etc., on the maximum fuel and pressure vessel temperature. The results show that the nominal peak fuel temperatures remain below 1600 deg. C for all these cases, which is the limiting temperature relating to radioactivity release from the fuel. The analyses presented in this paper demonstrate that the code THERMIX can be successfully applied for the thermal calculation of HTRs with prismatic fuel. The results also provide some fundamental information for the design optimization of V/HTR with respect to its maximum thermal power, operating

  3. The investigation of argon diffusion in phlogopite under high pressure conditions

    Science.gov (United States)

    Yudin, Denis; Korzhova, Sophia; Travin, Alexey; Zhimulev, Egor; Murzintsev, Nikolay; Moroz, Tatiana

    2014-05-01

    The present study deals with assessment of pressure effect on the mechanism of bleeding an argon from mica at high temperatures and pressures. The influence of pressure on the diffusion of argon in crustal conditions is not significant (Harrison et al., 2009), while in the mantle conditions, should be significant. The authors suggest that the findings will help to better understand the behavior of K/Ar isotopic system in mica under the lower crust and mantle, including xenoliths transport by kimberlite melt. The experiment was made by using high-pressure spacer "split-sphere" (BARS - 300). Phlogopite from veins cutting metamorphic rocks from the Sludyanka number 2 quarry was used as a testing material. Inclusions of other minerals were not found in the original phlogopite crystal. Chemical composition of phlogopite is homogeneous. 8 experiments was made at a constant pressure of 30 kbar and different temperature and duration: 20 degrees Celsius, 20 minutes; 700 degrees Celsius, 20 minutes; 800 degrees Celsius, 10 minutes; 800 degrees Celsius, 20 minutes; 800 degrees Celsius, 30 minutes; 900 degrees Celsius, 20 minutes; 1000 degrees Celsius, 20 minutes; 1100 degrees Celsius, 20 minutes. According the results of SEM-observation, there is no signs of recrystallization and solid state transformations and melting of phlogopite. It's chemical composition is identical to that of the original phlogopite. Diffractograms of phlogopites after the experiments are similar to the diffractograms of the original phlogopites. Research results of IR spectroscopy, together with the results of SEM and microprobe analysis suggest that phlogopite dehydroxylation in the temperature range T = 700-900 degrees Celsius was negligible. Numerical simulation of the behavior of radiogenic argon in phlogopite at high temperatures and pressure was performed using «Diffarg» software finite differences algorithm, based on the mechanism of bulk thermally activated diffusion (Wheeler, 1996). The

  4. 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

    International Nuclear Information System (INIS)

    Searching for small periodic signals, such as the 12 hr (S2) 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 S2 line is evidenced in radon concentration, with enhanced amplitude during transient radon bursts. Similarly, the S2 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 S2 line suggests sensitivity to barometric pressure, and thus a significant advective contribution in radon and some drip water transport. No S2 line is observed in the carbon dioxide time-series. The temporal structure of the S2 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 S2 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)

  5. 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)

  6. Water-levels fluctuations in a borehole at the Royal Observatory of Belgium: Effects on local gravity, Earth tidal, and barometric responses

    Science.gov (United States)

    Delcourt-Honorez, M.

    A borehole was drilled at the Royal Observatory of Belgium in Brussels, next to the superconducting gravimeter. Three aquifers belong to the 'multiple aquifer-aquitard system'. Continuously since Jun. 1984, various kinds of water levels variations are registered: long term and short term variations and, in the intermediate and deep wells, periodic tidal oscillations. Moreover, the water table and the pressure heads respond to the atmospheric pressure variations. The water levels variations perturbing effects in the superconducting gravimeter registrations are estimated and the hydraulic problem and the consolidation problem are studied. The classical Bouguer's formula in theories is enlarged, taking into account the nature of the layers, the expansions or compressions of each layer, the global land surface displacement and the various hydrostatic occurrences of phases on porous media. The Bouguer's theory is also extended to the case of a finite thickness layer, by a numerical integration. The water levels variations in the intermediate and deep aquifers (at long term, at short term, and the barometric and tidal responses) are only inducing negligible perturbing effects on the superconducting gravimeter registrations but the effect of the water table drift is at the limit of the actual precision of the gravimeter registrations. On the other hand, the barometric and tidal responses of the well-aquifer systems are used to estimate the in situ parameters of both the aquifers and the aquifer system (porosity, specific storage, vertical compressibility, and permeability). The estimated values are in good agreement with those deduced by using hydrogeological, soil, and rock mechanics considerations. The research presented can be applied to any hydrogeological configuration with any complexity.

  7. Natural Convective Heat and Mass Transfer of Water with Corrosion Products at Super—Critical Pressures under Cooling COnditions

    Institute of Scientific and Technical Information of China (English)

    Pei-XueJiang; Ze-PeiRen; 等

    1993-01-01

    A numerical study is reported of laminar natural convective heat and mass transfer on a vertical cooled plate for water containing metal corrosion products at super-critical pressures.The influence of variable properties at super-critical pressures on natural convertion has been analyzed.The difference between heat and mass transfer under cooling or heating conditions is also discussed and some correlations for heat and mass transfer under cooling conditions are recommended.

  8. Propagule pressure, habitat conditions and clonal integration influence the establishment and growth of an invasive clonal plant, Alternanthera philoxeroides

    OpenAIRE

    Wen-Hua eYou; Cui-min eHan; Long-xiang eFang; Dao-lin eDu

    2016-01-01

    Many notorious invasive plants are clonal, spreading mainly by vegetative propagules. Propagule pressure (the number of propagules) may affect the establishment, growth and thus invasion success of these clonal plants, and such effects may also depend on habitat conditions. To understand how propagule pressure, habitat conditions and clonal integration affect the establishment and growth of the invasive clonal plants, an 8-week greenhouse with an invasive clonal plant, Alternanthera philoxero...

  9. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  10. Characterization of transient discharges under atmospheric pressure conditions applying nitrogen photoemission and current measurements

    CERN Document Server

    Keller, Sandra; Bibinov, Nikita; Awakowicz, Peter

    2011-01-01

    Plasma parameters of three transient discharges (filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of an argon plasma coagulator) operated at atmospheric pressure conditions are determined applying a combination of diagnostics methods, namely numerical simulation, current measurement, and optical emission spectroscopy. These diagnostic methods supplement each other and resolve problems, which arise when these methods are used separately. Nitrogen is used as sensor gas and is admixed to argon for studying the argon plasma coagulator. The Boltzmann equation is solved in 'local' approximation to determine electron velocity distribution function. Drift velocity, electron-impact excitation rate constants for nitrogen molecular emission, electric current density, and emission spectrum of nitrogen molecule are calculated. Plasma parameters (electron velocity distribution function and electron density) are determined applying calculated as far as measured electric current, and ...

  11. 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.

  12. Natural Circulation Characteristics at Low-Pressure Conditions through PANDA Experiments and ATHLET Simulations

    Directory of Open Access Journals (Sweden)

    Domenico Paladino

    2008-01-01

    Full Text Available Natural circulation characteristics at low pressure/low power have been studied by performing experimental investigations and numerical simulations. The PANDA large-scale facility was used to provide valuable, high quality data on natural circulation characteristics as a function of several parameters and for a wide range of operating conditions. The new experimental data allow for testing and improving the capabilities of the thermal-hydraulic computer codes to be used for treating natural circulation loops in a range with increased attention. This paper presents a synthesis of a part of the results obtained within the EU-Project NACUSP “natural circulation and stability performance of boiling water reactors.” It does so by using the experimental results produced in PANDA and by showing some examples of numerical simulations performed with the thermal-hydraulic code ATHLET.

  13. Multipole Electrodynamic Ion Trap Geometries for Microparticle Confinement under Standard Ambient Temperature and Pressure Conditions

    CERN Document Server

    Mihalcea, Bogdan M; Stan, Cristina; Visan, Gina T; Ganciu, Mihai; Filinov, Vladimir E; Lapitsky, Dmitry S; Deputatova, Lidiya V; Syrovatka, Roman A

    2015-01-01

    Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in multipole linear Paul trap geometries, operating under Standard Ambient Temperature and Pressure (SATP) conditions. An 8-electrode and a 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of the microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap was mapped using the electrolytic tank method. Particle dynamics was simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.

  14. Designing an efficient microwave-plasma source, independent of operating conditions, at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Fleisch, T [Groupe de Physique des Plasmas, Universite de Montreal, Montreal H3C 3J7, Quebec (Canada); Kabouzi, Y [Groupe de Physique des Plasmas, Universite de Montreal, Montreal H3C 3J7, Quebec (Canada); Moisan, M [Groupe de Physique des Plasmas, Universite de Montreal, Montreal H3C 3J7, Quebec (Canada); Pollak, J [Groupe de Physique des Plasmas, Universite de Montreal, Montreal H3C 3J7, Quebec (Canada); Castanos-MartInez, E [Groupe de Physique des Plasmas, Universite de Montreal, Montreal H3C 3J7, Quebec (Canada); Nowakowska, H [Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 80-952 Gdansk (Poland); Zakrzewski, Z [The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 80-952 Gdansk (Poland)

    2007-02-15

    The surfaguide is a waveguide-based electromagnetic-surface-wave launcher that allows sustaining long plasma columns using microwaves. Its electrodynamic characteristics are examined experimentally and theoretically in the perspective of achieving an efficient plasma source without any need for impedance matching retuning as operating conditions are varied over a broad range. The plasma source design and its modelling using equivalent-circuit theory are described and a simple procedure is provided to determine the optimum dimensions of the surfaguide that maximize the transfer of microwave power to plasma. As an example, with an optimized surfaguide, the reflected power in an N{sub 2} discharge at atmospheric pressure stays below 3% for powers in the 2-6 kW range and gas flow rates in the 30-150 l min{sup -1} domain under varying concentrations (< 2%) of admixed gases such as SF{sub 6}, O{sub 2} and argon.

  15. Irradiation performance of (Th,Pu)O2 fuel under Pressurized Water Reactor conditions

    Science.gov (United States)

    Boer, B.; Lemehov, S.; Wéber, M.; Parthoens, Y.; Gysemans, M.; McGinley, J.; Somers, J.; Verwerft, M.

    2016-04-01

    This paper examines the in-pile safety performance of (Th,Pu)O2 fuel pins under simulated Pressurized Water Reactor (PWR) conditions. Both sol-gel and SOLMAS produced (Th,Pu)O2 fuels at enrichments of 7.9% and 12.8% in Pu/HM have been irradiated at SCK·CEN. The irradiation has been performed under PWR conditions (155 bar, 300 °C) in a dedicated loop of the BR-2 reactor. The loop is instrumented with flow and temperature monitors at inlet and outlet, which allow for an accurate measurement of the deposited enthalpy. Between 2004 and 2006, four fuel segments were irradiated, with on-line recording of centerline temperature and rod pressure of the two instrumented rods and intermittent non-destructive hot-cell investigations of the other two non-instrumented rods. At the end of 2006, the instrumented rods were unloaded for hot-cell investigations. The hot-cell investigations reduced uncertainties in the power history to build a reliable and consistent irradiation history which can be used to assess and validate fuel performance codes. The on-line recorded temperatures of the instrumented rods are presented in this paper and are compared to corresponding calculations on the basis of the power history. One of the non-instrumented rods was re-inserted in the reactor in 2012 and attained a peak burnup level of 37 GWd/tHM by the end of 2014. The combined data set of on-line measurements and post irradiation examinations enables further code validation. In this context, the results of the in-house MACROS code of SCK·CEN have been compared with the experimental results. The code contains dedicated (Th,Pu)O2 models for the calculation of the thermal conductivity as a function of the burnup and models that determine the radial power profile within the pellet.

  16. Mechanistic modeling of bearing pad to pressure tube contact under localized high temperature conditions in a CANDU fuel channel

    International Nuclear Information System (INIS)

    During a postulated critical break LOCA (loss of coolant accident) in a CANDU reactor the coolant flow rates in the fuel channels of the flow pass of the reactor core downstream of the pipe break can rapidly reduce to very low values and remain very low for a period of tens of seconds following the break. Under the sustained low flow conditions, the fuel sheath (cladding) temperature in the affected channels rapidly increases and the coolant in the channels becomes significantly voided. The pressure tubes in the affected pass heat up under a combination of convection heat transfer from the low flows of superheated seam and thermal radiation heat transfer from the hot fuel. Additionally, hot spots may develop on the inner surface of pressure tubes at locations where the fuel bearing pads are in direct contact with the pressure tube. Localized thermal creep strain deformation at the hot spots is a potential pressure tube failure mechanism which could challenge fuel channel integrity. This paper evaluates the local thermal-mechanical deformation of a pressure tube in a CANDU reactor under critical break LOCA conditions tube using a coupled thermal-mechanical finite element COMSOL multi-physics model and investigates the conditions resulting in fuel channel failure due to localized contact between bearing pad and pressure. The mechanistic models are validated against data obtained from COG funded experiments performed at WRL (Whiteshell Research Laboratory). Multiphysics calculations are performed in which the heat transfer, thermal-mechanical and creep strain equations are solved, simultaneously. Heat conduction from bearing pads to the inner surface of the pressure tube is modeled with appropriate convective and radiation heat transfer boundary conditions. Thermal creep strain deformation of the Zr-2.5%Nb pressure tube is modeled using correlations derived from separate uniaxial tests that are reported in the literature. Contact conductance models based on

  17. Effect on two-phase flow frictional pressure drop characteristic in narrow rectangular channel at fluctuant condition

    International Nuclear Information System (INIS)

    Based on the data of two-phase flow in narrow rectangular channel, the influence of the two-phase flow friction characteristic under the different fluctuant states was analyzed. Through analyzing the experimental data, it is shown that the fluctuant amplitude of the friction pressure drop is affected slightly by the fluctuant period in narrow rectangular channel, but the frequency of the friction pressure drop fluctuation is changed. However, the change of fluctuant period is of little effect on the average frictional pressure drop. Comparing the φl2 (φg2)-X variation curves at static condition with the ones at fluctuant condition, using the L-M method, it's found that the two phase frictional pressure drop in the narrow rectangular channel under the fluctuant state can be calculated by the φl2 (φg2)-X variation curve at static condition. (authors)

  18. Sufficient conditions for globally asymptotic self-stability of pressurized water reactors

    International Nuclear Information System (INIS)

    Highlights: • Self-stability analysis of the PWR is presented through the shifted-ectropy based approach. • Sufficient conditions for the globally asymptotic self-stability are established. • The correctness of the theoretic results are finally verified through numerical simulation. - Abstract: After the Fukushima accident, safe, stable and efficient operation of reactors is very necessary for the development of nuclear power industry. Since pressurized water reactor (PWR) is the mostly widely used fission reactor, the improvement of its operation performance is quite meaningful. Self-stability is the most important dynamic feature of any reactors, and analyzing the self-stability can give the approach of improving the operation performance. With this in mind, the self-stability analysis of the PWR is presented through the shifted-ectropy based approach, and sufficient conditions for the globally asymptotic self-stability in cases of negative, zero and positive coolant temperature feedback coefficient are all established. The correctness of the theoretical results are finally verified through numerical simulation. The results of this paper give the way to not only guaranteeing self-stability through physical and thermal-hydraulic reactor design but also strengthening closed-loop stability and robustness by the means of feedback control

  19. 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 (Ф = 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.

  20. Autonomic control of heart rate and blood pressure in spontaneously hypertensive rats during aversive classical conditioning.

    Science.gov (United States)

    Hatton, D C; Buchholz, R A; Fitzgerald, R D

    1981-12-01

    An examination was made of the heart rate (HR) and blood pressure (BP) responses of 7-9-wk-old spontaneously hypertensive rats (SHR) and genetical control Wistar/Kyoto (WKY) rats during aversive classical conditioning. Subsequent to the development of conditioned responding (CRs), assessments were made of the effects of selective autonomic blockade by methyl atropine (10 mg/kg), phentolamine (2 mg/kg), and propranolol (2 mg/kg). The CR complex in the two strains consisted of pressor BP CRs in conjunction with vagally mediated decelerative HR CRs in the SHR strain and sympathetically mediated accelerative HR CRs in the WKY strain. The decelerative SHR HR CR did not appear to be secondary to baroreceptor reflex activity, although such activity did appear to be involved in the pressor BP and decelerative HR orienting response (OR) and unconditioned response (UR) complex of the SHRs on the initial application of the CS and the US, respectively. Augmented pressor BP ORs, CRs, and URs in the SHRs relative to the WKYs and differential drug effects on BP and HR baselines of the two strains suggested the presence of enhanced sympathetic activity in the SHRs that was not reflected in the SHR decelerative HR CR. Phentolamine unmasked evidence of reflex beta 2-vasodilation deficiency in the SHRs that could have contributed to the enhancement of their BP OR and CR.

  1. 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)

    Kim, Seung Jun [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zou, Ling [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jones, Barclay G. [Univ. of Illinois, Urbana, IL (United States). Dept. of Nuclear, Plasma and Radiological Engineering

    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/m2s, (3) inlet sub-cooling enthalpy (ΔHi) of 12~ 26 kJ/kg. Parametric trends of macroscopic system parameters (G, P, Hi) 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.

  2. 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

  3. Weather conditions can influence rheumatic diseases.

    Science.gov (United States)

    Vergés, Josep; Montell, Eulàlia; Tomàs, Elena; Cumelles, Gemma; Castañeda, Guido; Marti, Núria; Möller, Ingrid

    2004-01-01

    In daily clinical practice, many patients attribute joint pain to weather conditions. There is little information published on this subject and most of it is contradictory. The objective of this study was to evaluate the effect of climatic conditions in rheumatic patients. The present work was carried out with patients attending the Instituto Poal de Reumatologia of Barcelona and the data were analyzed by Bioibérica Farma (Spain). It was a prospective, double-blind study including 92 patients with rheumatic disorders (80 with osteoarthritis, 12 with rheumatoid arthritis) compared to a control group of 42 subjects. The evaluation of pain (Huskisson VAS) and functional capacity (Health Assessment Questionnaire, HAQ) were determined daily during one month. The climatic variables studied were temperature, humidity and barometric pressure. The results obtained have been subject to binary regression analysis. Our data demonstrate that osteoarthritic patients experience increased joint pain in response to a decrease in pressure, indicating that low atmospheric pressure conditions exacerbate joint pain in these patients. Our work also suggests that some meteorological variables affect the occurrence of pain in rheumatoid arthritis, since we have found that low temperature increases the risk of joint pain. Therefore, these data suggest that in the future it may be possible to modulate pharmacological and non-pharmacological treatments for some osteoarthritic patients depending on the predictable weather conditions in order to avoid, as much as possible, the disease-associated joint pain and functional incapacity, thus improving patients' quality of life.

  4. Measurement of subcooled boiling pressure drop and local heat transfer coefficient in a horizontal channel under LPLF conditions

    International Nuclear Information System (INIS)

    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, experimental measurements of local heat transfer coefficient and pressure drop are carried out in a horizontal channel under LPLF conditions of sub-cooled boiling. Infrared 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 sub-cooled boiling conditions as a function of Bo (Boiling number) and Ja (Jacob number) is obtained. Correlation for single phase heat transfer coefficient in the developing region is presented as a function of z/d (ratio of axial length of the test section to diameter). Correlation for two-phase heat transfer coefficient under sub-cooled boiling condition is presented as a function of Bo, Ja and Pr (Prandtl number). Correlation between heat transfer coefficient and friction factor is obtained by applying Reynolds analogy. (author)

  5. Socket Interface Pressure and Amputee Reported Outcomes for Comfortable and Uncomfortable Conditions of Patellar Tendon Bearing Socket: A Pilot Study.

    Science.gov (United States)

    Safari, Mohammad Reza; Tafti, Nahid; Aminian, Gholamreza

    2015-01-01

    The objectives of the current study were to compare intra-socket pressure differences between comfortable and uncomfortable socket conditions, and the usefulness of subject perception of satisfaction, activity limitations, and socket comfort in distinguishing between these two socket conditions. Five unilateral trans-tibial amputees took part in the study. They answered the Socket Comfort Score (SCS) and Trinity Amputation and Prosthetic Experience Scale (TAPES) questionnaires before the interface pressure (in standing and walking) was measured for the uncomfortable socket condition at five regions of the residual limb. Participants were then provided with a comfortable socket and wore it for two weeks. Participants who were satisfied with the socket fit after two weeks repeated the SCS and TAPES questionnaires and interface pressure measurements. The differences between the test results of the two conditions were not statistically significant, except for the interface pressure at the popliteal region during the early stance phase, TAPES socket fit subscale, and the SCS. Due to large variability of the data and the lack of statistical significance, no firm conclusion can be made on the possible relationship between the interface pressure values and the patient-reported outcomes of the two socket conditions. A larger sample size and longer acclimation period are required to locate significant differences.

  6. Artificially decreased vapour pressure deficit in field conditions modifies foliar metabolite profiles in birch and aspen.

    Science.gov (United States)

    Lihavainen, Jenna; Keinänen, Markku; Keski-Saari, Sarita; Kontunen-Soppela, Sari; Sõber, Anu; Oksanen, Elina

    2016-07-01

    Relative air humidity (RH) is expected to increase in northern Europe due to climate change. Increasing RH reduces the difference of water vapour pressure deficit (VPD) between the leaf and the atmosphere, and affects the gas exchange of plants. Little is known about the effects of decreased VPD on plant metabolism, especially under field conditions. This study was conducted to determine the effects of artificially decreased VPD on silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L.×P. tremuloides Michx.) foliar metabolite and nutrient profiles in a unique free air humidity manipulation (FAHM) field experiment during the fourth season of humidity manipulation, in 2011. Long-term exposure to decreased VPD modified nutrient homeostasis in tree leaves, as demonstrated by a lower N concentration and N:P ratio in aspen leaves, and higher Na concentration and lower K:Na ratio in the leaves of both species in decreased VPD than in ambient VPD. Decreased VPD caused a shift in foliar metabolite profiles of both species, affecting primary and secondary metabolites. Metabolic adjustment to decreased VPD included elevated levels of starch and heptulose sugars, sorbitol, hemiterpenoid and phenolic glycosides, and α-tocopherol. High levels of carbon reserves, phenolic compounds, and antioxidants under decreased VPD may modify plant resistance to environmental stresses emerging under changing climate.

  7. High Pressure Compression-Molding of α-Cellulose and Effects of Operating Conditions

    Directory of Open Access Journals (Sweden)

    Antoine Rouilly

    2013-05-01

    Full Text Available Commercial α-cellulose was compression-molded to produce 1A dog-bone specimens under various operating conditions without any additive. The resulting agromaterials exhibited a smooth, plastic-like surface, and constituted a suitable target as replacement for plastic materials. Tensile and three-points bending tests were conducted according to ISO standards related to the evaluation of plastic materials. The specimens had strengths comparable to classical petroleum-based thermoplastics. They also exhibited high moduli, which is characteristic of brittle materials. A higher temperature and higher pressure rate produced specimens with higher mechanical properties while low moisture content produced weaker specimens. Generally, the strong specimen had higher specific gravity and lower moisture content. However, some parameters did not follow the general trend e.g., thinner specimen showed much higher Young’s Modulus, although their specific gravity and moisture content remained similar to control, revealing a marked skin-effect which was confirmed by SEM observations.

  8. Main mechanisms of material properties degradation under reactor pressure vessel operating conditions

    International Nuclear Information System (INIS)

    In the process of NPP equipment operation materials are subjected to a prolonged influence of loads, associated with the variation of inner pressure and temperature under various conditions. Each equipment element damage is associated with some material fracture mechanism. For NPP equipment the mechanisms of irreversible damage accumulation are related with: irradiation embrittlement, thermal and strain aging, fatigue damages from mechanical and thermal loading, stress corrosion and fatigue corrosion, creep and thermal relaxation stresses, erosion and weak, thermal shock. The basic tasks of specialists working in the sphere of the provision of reliability and service life of nuclear power equipment are not only the determination of the main mechanisms of damages and reasons of their appearance, but also the study of methods which would permit to control these properties completely. By giving some examples of Russian NPP equipment with VVER-440 and VVER-1000 reactors the paper presents most typical degradation mechanisms of equipment material properties, including weldments, in the process of operation and methods to recover by using various technological means. (author)

  9. 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.

  10. Lattice Boltzmann simulations of pressure-driven flows in microchannels using Navier–Maxwell slip boundary conditions

    KAUST Repository

    Reis, Tim

    2012-01-01

    We present lattice Boltzmann simulations of rarefied flows driven by pressure drops along two-dimensional microchannels. Rarefied effects lead to non-zero cross-channel velocities, nonlinear variations in the pressure along the channel. Both effects are absent in flows driven by uniform body forces. We obtain second-order accuracy for the two components of velocity the pressure relative to asymptotic solutions of the compressible Navier-Stokes equations with slip boundary conditions. Since the common lattice Boltzmann formulations cannot capture Knudsen boundary layers, we replace the usual discrete analogs of the specular diffuse reflection conditions from continuous kinetic theory with a moment-based implementation of the first-order Navier-Maxwell slip boundary conditions that relate the tangential velocity to the strain rate at the boundary. We use these conditions to solve for the unknown distribution functions that propagate into the domain across the boundary. We achieve second-order accuracy by reformulating these conditions for the second set of distribution functions that arise in the derivation of the lattice Boltzmann method by an integration along characteristics. Our moment formalism is also valuable for analysing the existing boundary conditions. It reveals the origin of numerical slip in the bounce-back other common boundary conditions that impose conditions on the higher moments, not on the local tangential velocity itself. © 2012 American Institute of Physics.

  11. The role of mechanical pressure difference in the generation of membrane voltage under conditions of concentration polarization.

    Science.gov (United States)

    Grzegorczyn, Sławomir; Ślęzak, Andrzej

    2016-06-01

    The mechanical pressure difference across the bacterial cellulose membrane located in a horizontal plane causes asymmetry of voltage measured between electrodes immersed in KCl solutions symmetrically on both sides of the membrane. For all measurements, KCl solution with lower concentration was above the membrane. In configuration of the analyzed membrane system, the concentration boundary layers (CBLs) are created only by molecular diffusion. The voltages measured in the membrane system in concentration polarization conditions were compared with suitable voltages obtained from the model of diffusion through CBLs and ion transport through the membrane. An increase of difference of mechanical pressure across the membrane directed as a difference of osmotic pressure always causes a decrease of voltage between the electrodes in the membrane system. In turn, for mechanical pressure difference across the membrane directed in an opposite direction to the difference of osmotic pressure, a peak in the voltage as a function of mechanical pressure difference is observed. An increase of osmotic pressure difference across the membrane at the initial moment causes an increase of the maximal value of the observed peak and a shift of this peak position in the direction of higher values of the mechanical pressure differences across the membrane. PMID:27060081

  12. Navier-Stokes equations with periodic boundary conditions and pressure loss

    OpenAIRE

    Amrouche, Chérif; Batchi, Macaire; Batina, Jean

    2007-01-01

    10 pages. We present in this note the existence and uniqueness results for the Stokes and Navier-Stokes equations which model the laminar flow of an incompressible fluid inside a two-dimensional channel of periodic sections. The data of the pressure loss coefficient enables us to establish a relation on the pressure and to thus formulate an equivalent problem.

  13. 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.)

  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 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. Controlling and assessing pressure conditions during treatment of tar sands formations

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Etuan; Beer, Gary Lee

    2015-11-10

    A method for treating a tar sands formation includes providing heat to at least part of a hydrocarbon layer in the tar sands formation from a plurality of heaters located in the formation. Heat is allowed to transfer from the heaters to at least a portion of the formation. A pressure in the portion of the formation is controlled such that the pressure remains below a fracture pressure of the formation overburden while allowing the portion of the formation to heat to a selected average temperature of at least about 280.degree. C. and at most about 300.degree. C. The pressure in the portion of the formation is reduced to a selected pressure after the portion of the formation reaches the selected average temperature.

  16. Near-Surface and Bulk Behavior of Bicontinuous Microemulsions under High-Pressure Conditions.

    Science.gov (United States)

    Berghaus, Melanie; Paulus, Michael; Salmen, Paul; Al-Ayoubi, Samy; Tolan, Metin; Winter, Roland

    2016-07-28

    The effect of hydrostatic pressure on the structure of a bicontinuous microemulsion in the presence of a solid interface has been studied by X-ray reflectometry and compared to the bulk behavior determined by small-angle X-ray scattering. Surface-induced lamellar ordering is observed close to the hydrophilic interface, which persists upon compression. The lamellar domains are compressed, but the correlation length of lamellar order does not change with pressure. SAXS measurements on the bulk microemulsion revealed an increased order upon pressurization. Although pressure can cause the formation of highly ordered lamellar phases from ordered bicontinuous cubic phases, such a scenario is not observed for the disordered analogue studied here. High pressure increases the stiffness of the interfacial surfactant layer, but this is not sufficient to overcome the loss in conformational entropy that would result from a transition to an ordered lamellar phase. Possible technological and biological implications of our results are briefly discussed. PMID:27387338

  17. Optimization of Inactivation Conditions of High Hydrostatic Pressure Using Response Surface Methodology

    Institute of Scientific and Technical Information of China (English)

    GAO Yu-long; WANG Yun-xiang; JIANG Han-hu

    2004-01-01

    Response surface methodology(RSM)was employed in the present work and a second order quadratic equation for high hydrostatic pressure(HHP)inactivation was built.The adequacy of the model equation for predicting the optimum response values was verified effectively by the validation data.Effects of temperature,pressure,and pressure holding time on HHP inactivation of Escherichia coli ATCC 8739 were explored.By analyzing the response surface plots and their corresponding contour plots as well as solving the quadratic equation,the optimum process parameters for inactivation E.coli of six log cycles were obtained as:temperature 32.2℃,pressure 346.4 MPa,and pressure holding time 12.6 min.

  18. 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; Petersen, Søren Vermehren;

    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...

  19. 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...

  20. Propagule Pressure, Habitat Conditions and Clonal Integration Influence the Establishment and Growth of an Invasive Clonal Plant, Alternanthera philoxeroides.

    Science.gov (United States)

    You, Wen-Hua; Han, Cui-Min; Fang, Long-Xiang; Du, Dao-Lin

    2016-01-01

    Many notorious invasive plants are clonal, spreading mainly by vegetative propagules. Propagule pressure (the number of propagules) may affect the establishment, growth, and thus invasion success of these clonal plants, and such effects may also depend on habitat conditions. To understand how propagule pressure, habitat conditions and clonal integration affect the establishment and growth of the invasive clonal plants, an 8-week greenhouse with an invasive clonal plant, Alternanthera philoxeroides was conducted. High (five fragments) or low (one fragment) propagule pressure was established either in bare soil (open habitat) or dense native vegetation of Jussiaea repens (vegetative habitat), with the stolon connections either severed from or connected to the relatively older ramets. High propagule pressure greatly increased the establishment and growth of A. philoxeroides, especially when it grew in vegetative habitats. Surprisingly, high propagule pressure significantly reduced the growth of individual plants of A. philoxeroides in open habitats, whereas it did not affect the individual growth in vegetative habitats. A shift in the intraspecific interaction on A. philoxeroides from competition in open habitats to facilitation in vegetative habitats may be the main reason. Moreover, clonal integration significantly improved the growth of A. philoxeroides only in open habitats, especially with low propagule pressure, whereas it had no effects on the growth and competitive ability of A. philoxeroides in vegetative habitats, suggesting that clonal integration may be of most important for A. philoxeroides to explore new open space and spread. These findings suggest that propagule pressure may be crucial for the invasion success of A. philoxeroides, and such an effect also depends on habitat conditions. PMID:27200041

  1. 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; Presz, W.;

    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...

  2. Thermal Diffused Scattering (TDS) - a new tool for determining single crystal elasticity at high-pressure condition

    Science.gov (United States)

    Zhang, J.

    2015-12-01

    X-ray thermal diffuse scattering (TDS) has been used to determine phonon dispersion relation of solids since 1940s (Wehinger et al. 2013; Ding et al. 2006; Xu and Chiang 2005). However, its application in high-pressure mineral physics has not been widely recognized. Sound velocities of Earth materials at relevant high pressure (P) and temperature (T) conditions are essential for interpreting seismic data, which provides by now the most accurate image of the Earth interior. Comparing with other commonly used techniques for measuring sound velocities in the high-pressure mineral physics community, it has significant advantages and disadvantages. Firstly, it could be used for measuring any single crystals at extreme P-T conditions using diamond anvil cell (DAC), not limited to transparent samples or nuclear resonant isotopes; Secondly, single-crystal elastic constants could be obtained through TDS, and hence directional dependences of sound velocities are available; Finally, experimental setup for TDS measurement is very easy, essentially identical to what is used for routine high-pressure single-crystal X-ray diffraction experiments. However, TDS is much less straightforward in data interpretation, which usually involves micro force constant modeling between the nearest neighbor atoms. We developed dependable data collection procedures for TDS measurement under high-pressure conditions. Measurements with single-crystal Si and foresterite under ambient and high-pressure conditions are successful. Using the python code package we developed for analyzing TDS data, we successfully reproduced the previously determined single-crystal elastic moduli of Si and foresterite using Brillouin spectroscopy and ultrasonics. The experimental uncertainty of the single crystal elastic moduli determined from TDS approach is within 4% or better.

  3. Characterization of Contaminant Transport by Gravity, Capillarity and Barometric Pumping in Heterogeneous Vadose Zones

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C R; Martins, S A; Ramirez, A L; Daily, W D; Hudson, G B; Ralsont, D; Ekwurzel, B

    2001-02-27

    This final report summarizes the work and accomplishments of our three-year project. We 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. Our 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. The key feature of the VZO constructed at Lawrence Livermore National Laboratory (LLNL) is the variety of plume-tracking techniques that can be used at a single location. Electric resistance tomography (ERT) uses vertical arrays of electrodes across the vadose zone that can monitor electrical resistance changes in the soil as a plume moves downward to the water table. These resistance changes can be used to provide ''snapshots'' of the progress of the plume. Additionally, monitoring wells have been completed at multiple levels in the vicinity of a central infiltration site. Sensors emplaced at different levels include electrically conducting gypsum blocks for detecting saturation changes, thermistors for monitoring temperature changes and pressure transducers for observing barometric changes at different levels in the vadose regime. The data from these sensors are providing important information about the state of the gas- and liquid-phase dynamics of the infiltration process. Similarly, access ports at different levels have been used to supply gas-phase samples while lysimeters yield liquid-phase samples. Studies involving gas-phase tracers were carried out at LLNL and at an Orange County Water District site in southern California to evaluate the time-dependent chemical signature of a plume that was spiked with an array of dissolved noble-gas tracers. Our work also correlate chemical signatures with those of the above-mentioned sensors that track

  4. Acute and Conditioned Blood Pressure Changes in Relation to Social and Psychosocial Stimuli in Rats

    OpenAIRE

    Fokkema, Dirk S.; Koolhaas, Jaap M.

    1985-01-01

    The naturally occurring tendency to compete with other rats for territorial space has been used to study individual behavior characteristics and blood pressure reactivity to social stimuli in adult male TMD-S3 rats. The competitive characteristics of the individual rats are consistent in two different social situations (victory and defeat). Blood pressure responses during the victory of home territory rats over intruders was more pronounced in the more competitive animals. In addition to defe...

  5. Ionospheric Response to Solar Wind Pressure Pulses Under Northward IMF Conditions

    Directory of Open Access Journals (Sweden)

    Kan Liou

    2013-01-01

    Full Text Available Enhancements of aurora and auroral electrojets in response to sudden compression of the magnetosphere by shocks/pressure pulses are well known and have been attributed by some to compression-enhanced magnetic field reconnection. To examine such a view, we analyze a fortuitous event that is comprised of a series of pressure pulses (< 20 min on November 8, 2000. These pressure pulses were preceded by a large, northward interplanetary magnetic field (IMF that lasted more than 15 hours such that effects from reconnection can be minimized. Auroral images acquired by ultraviolet imager on board the Polar satellite clearly show intensifications of the aurora that occurred first near local noon and progressively extended from dayside to nightside. The area-integrated global auroral power reached ~30 gigawatts (GW. It is also found that the global auroral power is well correlated with the solar wind dynamic pressure (correlation coefficient r ~0.90, rather than the change in the solar wind dynamic pressure. In-situ measurements of particle data from the Defense Meteorological Satellite Program satellite indicate that the magnetospheric source for the pressure-enhanced auroras is most likely the central plasma sheet. Other ionospheric parameters such as the auroral electrojet (AE index, magnetic storm index (Sym-H, and the cross polarcap potential drop also show a one-to-one correspondence to the pressure pulses. In one instance the auroral electrojets AE index reached more than 200 nT, the cross polar-cap potential drop (Φpc inferred from the SuperDARN radar network ionospheric plasma convection increased to ~60 kV. The observed increases in the auroral emissions, AE, and polar cap potential were not associated with substorms. Our result strongly suggests that solar wind pressure pulses are an important source of geomagnetic activity during northward IMF periods.

  6. Volume based vs. time based chromatograms: reproducibility of data for gradient separations under high and low pressure conditions.

    Science.gov (United States)

    Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Vajda, Péter; Beaver, Lois Ann; Guiochon, Georges

    2014-05-23

    A critical aspect in fast gradient separations carried out under constant pressure, in the very high pressure liquid chromatography (VHPLC) mode is that time-based chromatograms may not yield highly reproducible separations. A proposed solution to improve the reproducibility of these separations involves plotting the chromatograms as functions of the volume eluted vs. UV absorbance instead of time vs. UV. To study the consequences of using the volume-based rather than the time-based chromatograms, separations were first performed under low pressures that do not generate significant amounts of heat and for which the variations of the eluent density along the columns are negligible. Secondly, they were performed under very high pressures that do generate heat and measurable variations of the local retention factor and eluent density along the column. Comparison of the results provides estimates of the improvements obtained when volume based chromatograms are used in gradient analyses. Using a column packed with fully porous particles, four different types of methods and several sets for each method were used to perform the gradient elution runs: two sets of constant flow rate operations, four sets of constant pressure operations, two sets of constant pressure operations with programmed flow rate, and one set using the constant heat loss approach. The differences between time-based and volume-based chromatograms are demonstrated by using eight replicates of early, middle, and last eluting peaks. The results show that volume-based chromatograms improve the retention time reproducibility of the four constant pressure methods by a factor of 3.7 on average. If the column is not thermally conditioned prior to performing a long series of separations, flow controlled methods (constant flow rate, programmed constant pressure, and constant wall heat approaches) are more precise. If one gradient run is used to bring the column to a relatively stable temperature, constant

  7. Pressure-induced phase transformations in mineral chalcocite, Cu{sub 2}S, under hydrostatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Santamaria-Perez, D., E-mail: dsantamaria@quim.ucm.es [Departamento de Física Aplicada-ICMUV, Universidad de Valencia, C/Dr. Moliner 50, 46100 Burjassot, Valencia (Spain); Earth Sciences Department, University College London, Gower Street, WC1E 6BT London (United Kingdom); Garbarino, G. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex (France); Chulia-Jordan, R. [Departamento de QuimicaFisica I, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Dobrowolski, M.A. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex (France); Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland); Mühle, C.; Jansen, M. [Max-Planck Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

    2014-10-15

    Highlights: • Three previously unknown phase transitions have been found in Cu{sub 2}S. • The initial monoclinic phase transforms into two different monoclinic structures. • The compressibility of the low- and high-pressure phases has been determined. • Our results differ from those recently reported for Cu{sub 2}S nanowires. - Abstract: High-pressure room-temperature angle-dispersive powder X-ray diffraction measurements on Cu{sub 2}S chalcocite were performed up to 30 GPa using a diamond-anvil cell, He as pressure transmitting medium and synchrotron radiation. Two first-order phase transitions were found at 3.2 and 7.4 GPa. The indexation of the powder diffraction patterns suggests three different monoclinic cells for the low-pressure chalcocite and the two high-pressure phases. Subtle changes in the X-ray diffraction patterns suggest a third pressure-induced transition above 26 GPa. Structural parameters and compressibility are discussed and compared to those reported in a previous study on Cu{sub 2}S nanowires.

  8. Kinetics of diamond-silicon reaction under high pressure-high temperature conditions

    Science.gov (United States)

    Pantea, Cristian

    In this dissertation work, the kinetics of the reaction between diamond and silicon at high pressure-high temperature conditions was investigated. This study was motivated by the extremely limited amount of information related to the kinetics of the reaction in diamond-silicon carbide composites formation. It was found that the reaction between diamond and melted silicon and the subsequent silicon carbide formation is a two-stage process. The initial stage is a result of direct reaction of melted silicon with carbon atoms from the diamond surface, the phase boundary reaction. Further growth of SiC is much more complicated and when the outer surfaces of diamond crystals are covered with the silicon carbide layer it involves diffusion of carbon and silicon atoms through the SiC layer. The reaction takes place differently for the two regions of stability of carbon. In the graphite-stable region, the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, while in the diamond-stable region there is no intermediary step for the reaction. The data obtained at HPHT were fitted by the Avrami-Erofeev equation. It was found that the reaction is isotropic, the beta-SiC grown on different faces of the diamond crystals showing the same reaction rate, and that the controlling mechanism for the reaction is the diffusion. In the graphite-stable region the activation energy, 402 kJ/mol is slightly higher than in the diamond-stable region, 260 kJ/mol, as the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, which has higher activation energy. In the diamond-stable region, the calculated activation energy is higher for micron size diamond powders (≈260 kJ/mol), while for nanocrystalline diamond powders a lower value of 170 kJ/mol was obtained. This effect was attributed to nanocrystalline structure and strained bonds within grain boundaries in SiC formed from nanosize diamond

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

    Energy Technology Data Exchange (ETDEWEB)

    Meliksetian, A.; Sklencar, A.M.

    1982-12-01

    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.

  10. The effect of spacer grid critical component on pressure drop under both single and two phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Han, B.; Yang, B.W.; Zhang, H.; Mao, H.; Zha, Y. [Xi' an Jiaotong Univ., Shaanxi (China). Science and Technology Center for Advanced Nuclear Fuel Research

    2016-07-15

    As pressure drop is one of the most critical thermal hydraulic parameters for spacer grids the accurate estimation of it is the key to the design and development of spacer grids. Most of the available correlations for pressure drop do not contain any real geometrical parameters that characterize the grid effect. The main functions for spacer grid are structural support and flow mixing. Once the boundary sublayer near the rod bundle is disturbed, the liquid forms swirls or flow separation that affect pressure drop. However, under two phase flow conditions, due to the existence of steam bubble, the complexity for spacer grid are multiplied and pressure drop calculation becomes much more challenging. The influence of the dimple location, distance of mixing vane to the nearest strip, and the effect of inter-subchannel mixing among neighboring subchannels on pressure drop and downstream flow fields are analyzed in this paper. Based on this study, more detailed space grid geometry parameters are recommended for adding into the correlation when predicting pressure drop.

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

    Science.gov (United States)

    Sanjay Kumar, N R; Chandra Shekar, N V; Chandra, Sharat; Basu, Joysurya; Divakar, R; Sahu, P Ch

    2012-09-12

    We report here, for the first time, synthesis of the Fe(2)N 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 Ru(2)C at ambient pressure are found to be a = 2.534 Å and c = 4.147 Å. 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 Ru(2)C has significant implications in the synthesis and study of osmium carbides. PMID:22906879

  12. Convective Heat and Mass Transfer in Water at Super—Critical Pressures under Heating or Cooling Conditions in Vertical Tubes

    Institute of Scientific and Technical Information of China (English)

    Pei-XueJiang; Ze-PeiRen; 等

    1995-01-01

    Forced and mixed convection heat and mass transfer are studied numerically for water containing metallic corrosion products in a heated or cooled vertical tube with variable thermophysical properties at super-citical pressures.the fouling mechanisms and fouling models are presented.The influence of variable properties at super-critical pressures on forced or mixed convection has been analyzed.The differences between heat and mass transfer under heating and cooling conditions are discussed.It is found that variable properties,especially buoyancy,greatly influence the fluid flow and heat mass fransfer.

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

    DEFF Research Database (Denmark)

    Periotto, Benedetta; Balic Zunic, Tonci; Nestola, Fabrizio;

    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...... 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...

  14. Scaling of conditional Lagrangian time correlation functions of velocity and pressure gradient magnitudes in isotropic turbulence

    CERN Document Server

    Yu, Huidan

    2009-01-01

    We study Lagrangian statistics of the magnitudes of velocity and pressure gradients in isotropic turbulence by quantifying their correlation functions and their characteristic time scales. It has been found that the Lagrangian time-correlations of the velocity and pressure gradient tensor and vector elements scale with the locally-defined Kolmogorov time scale, defined from the box-averaged dissipation-rate and viscosity. In this work, we study the Lagrangian time-correlations of the absolute values of velocity and pressure gradients. We explore the appropriate temporal scales with the aim to achieve collapse of the correlation functions. The data used in this study are sampled from the web-services accessible public turbulence database(http://turbulence.pha.jhu.edu). The database archives a pseudo-spectral direct numerical simulation of forced isotropic turbulence with Taylor-scale Reynolds number 433, and supports spatial differentiation and spatial/temporal interpolation inside the database. The analysis s...

  15. 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.

  16. Acute and Conditioned Blood Pressure Changes in Relation to Social and Psychosocial Stimuli in Rats

    NARCIS (Netherlands)

    Fokkema, Dirk S.; Koolhaas, Jaap M.

    1985-01-01

    The naturally occurring tendency to compete with other rats for territorial space has been used to study individual behavior characteristics and blood pressure reactivity to social stimuli in adult male TMD-S3 rats. The competitive characteristics of the individual rats are consistent in two differe

  17. Land use change under conditions of high population pressure : the case of Java

    NARCIS (Netherlands)

    Verburg, P.H.; Veldkamp, A.; Bouma, J.

    1999-01-01

    A long history of increases in population pressure in Java has caused agricultural land use to expand and intensify. More recent land use changes caused the conversion of prime agricultural land into residential and industrial area. Results of a dynamic, regional-scale, land use change model are pre

  18. TURBULENCE SETS THE INITIAL CONDITIONS FOR STAR FORMATION IN HIGH-PRESSURE ENVIRONMENTS

    International Nuclear Information System (INIS)

    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 < 105 K cm–3) molecular clouds in the solar neighborhood. However, it is unknown whether or not these theories extend to clouds in high-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

  19. TURBULENCE SETS THE INITIAL CONDITIONS FOR STAR FORMATION IN HIGH-PRESSURE ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Rathborne, J. M.; Contreras, Y. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW, 1710 (Australia); Longmore, S. N.; Bastian, N. [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Jackson, J. M. [Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States); Kruijssen, J. M. D. [Max-Planck Institut fur Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748, Garching (Germany); Alves, J. F. [University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Bally, J. [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 8030 (United States); Foster, J. B. [Department of Astronomy, Yale University, P.O. Box 208101 New Haven, CT 06520-8101 (United States); Garay, G. [Universidad de Chile, Camino El Observatorio1515, Las Condes, Santiago (Chile); Testi, L. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Munchen (Germany); Walsh, A. J., E-mail: Jill.Rathborne@csiro.au [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth (Australia)

    2014-11-10

    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{sup 5} K cm{sup –3}) molecular clouds in the solar neighborhood. However, it is unknown whether or not these theories extend to clouds in high-pressure (P/k > 10{sup 7} K cm{sup –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.

  20. Experimental investigations of BWR pressure suppression pool behavior under loss of coolant accident conditions

    International Nuclear Information System (INIS)

    The experiments discussed in this paper look into different processes which may occur during a loss-of-coolant accident in the pressure suppression pool of a Boiling Water Reactor (BWR). These processes include: a) development of a thermal stratification, b) bubble dynamics and related water flow during continuous release of air and c) air blowdown and associated water slug phenomenon in the water pool. The experiments have been performed in the THAI test facility, which is a cylindrical vessel of 9.2 m height, 3.2 m diameter and with a gas volume of 60 m3. The variation in the investigated test parameters included, steam and air mass flux, initial water pool temperature, blowdown pressures, downcomer submergence, etc. A systematic variation of the test parameters allowed better understanding of the phenomena. Experiments discussed in this paper were performed with a vertical downcomer of 0.1 m diameter and 2 m submergence depth in the water pool. For the blowdown experiments, a separate interconnecting vessel of 1 m3 volume was used to inject air at pressures between 3 bar and 10 bar. A high speed camera (1000 fps) was installed to visualize the formation and propagation of air bubbles in the suppression pool and the resulting pool swelling phenomena. Customized instrumentation applied during the tests included grids of densely spaced thermocouples and of pressure transducers at various locations in order to capture the temperature distribution in the pool and the water slug induced pressure loadings, respectively. The present paper discusses the main outcome of the selected experiments. On the whole the experimental data may be very useful for code validation. (authors)

  1. Microstructure of nano and micron size diamond-silicon carbide composites sintered under high pressure high temperature conditions

    Science.gov (United States)

    Nauyoks, Stephen Edwin

    Compacts and composites were sintered under high pressure (2 GPa--10 GPa) and high temperature (1400--2300°C) conditions. The compacts were sintered using nano-SiC powder, micron-diamond powder, and nano-diamond powder. Composites were sintered using the liquid infiltration method from nano-silicon powder and nano or micron diamond powder. Under the high pressure, high temperature conditions the silicon powder would melt and react with carbon from the diamonds to form a SiC matrix. The microstructure and strain of the composites and compacts was analyzed using X-ray diffraction analysis. The extended convolutional multiple whole profile fitting method was used to analyze the X-ray line profiles to determine average crystallite size, dislocation density, and planar fault probability. The apparent lattice parameter method was used to analyze strain. Below a certain pressure there was subgrain growth. However, at the higher pressures there was a reduction in crystallite size. In the SiC phase there was a correlation between predominate defect, dislocation or planar fault, and the crystallite size. The defect structure of the diamonds seemed to be dependent on the initial diamond powder used. At higher temperatures there was evidence of recovery and or recrystallization.

  2. 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.

  3. 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

  4. COMPARISON OF VENTED AND ABSOLUTE PRESSURE TRANSDUCERS FOR WATER-LEVEL MONITORING IN HANFORD SITE CENTRAL PLATEAU WELLS

    Energy Technology Data Exchange (ETDEWEB)

    MCDONALD JP

    2011-09-08

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, S.; Seifert, H.P. [Paul Scherrer Institute, PSI, Villigen (Switzerland); Devrient, B.; Roth, A. [Framatome ANP GmbH, Erlangen (Germany); Ehrnsten, U. [VTT Industrial Systems, Espoo (Finland); Ernestova, M.; Zamboch, M. [Nuclear Research Institute, NRI, Rez (Czech Republic); Foehl, J.; Weissenberg, T. [Staatliche Materialpruefungsanstalt, MPA, Stuttgart (Germany); Gomez-Briceno, D.; Lapena, J. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, CIEMAT, Madrid (Spain)

    2004-07-01

    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)

  6. Spectral characteristics of atmospheric pressure and electric field variations under severe weather conditions at high latitudes

    OpenAIRE

    Kasatkina, E. A.; Shumilov, O. I.; Vinogradov, Y. A.; Vasilyev, A. N.

    2006-01-01

    International audience The time-dependent relationships between atmospheric parameters (electric field, positive and negative conductivity, variations of atmospheric pressure) and different meteorological phenomena (rain, fogs, snowstorms, thunderstorms) were investigated through spectral analysis. These parameters were measured with help of a high-latitude computer-aided complex installed at Apatity (66.5 N, 33.4 E). The complex consists of three spaced microbarographs for measurements of...

  7. 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...

  8. NUMERICAL SIMULATION STUDY ON SURFACTANT FLOODING FOR LOW PERMEABILITY OILFIELD IN THE CONDITION OF THRESHOLD PRESSURE

    Institute of Scientific and Technical Information of China (English)

    YIN Dai-yin; PU Hui

    2008-01-01

    Based on the non-Darcy flow characteristics of surfactant flooding in the low permeability oilfield, considering the changes of threshold pressure and influence of surfactant on convection, diffusion, adsorption and retention, a mathematical model is established for a three-dimensional, two-phase, three-component surfactant flooding. A new treatment for the changes of threshold pressure and a novel correction method for the relative permeability curve in the process of surfactant flooding are derived, which enhances the matching degree between the mathematical model and field practice. The mathematical model was used to perform the numerical simulation study for a pilot test of surfactant flooding in Chao 45 Block of Daqing Oilfield, a proper injection plan was optimized. After the optimized plan was carried out in oilfield, the desirable effects, like pressure-reducing, injection rate increase, and the increase of oil recovery, were achieved. The average oil increase for single well reaches 37%, the ratio of cost to revenue is above 1:4, so the economic effect of scale is promising.

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

    Energy Technology Data Exchange (ETDEWEB)

    Itagaki, M. (Japan Atomic Energy Research Inst., Dept. of Nuclear Ship Engineering, Aza-Kitasekine, Oaza-Sekine, Mutsu, Aomori 035 (JP)); Brebbia, C.A. (Computational Mechanics Inst., Ashurst Lodge, Ashurst, Southampton SO4 2AA (GB))

    1991-03-01

    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.

  10. Development of CHF correlation “MG-NV” for low pressure and low velocity conditions applied to PWR safety analysis

    International Nuclear Information System (INIS)

    The Critical Heat Flux (CHF) is one of the important parameters in the safety analysis of Pressurized Water Reactor (PWR). If the CHF is reached, an abrupt drop occurs in the heat transfer between the fuel rod cladding and the reactor coolant, which may induce a large temperature excursion of fuel cladding and a subsequent fuel failure. Therefore, accurate prediction of CHF is required in order to assure a sufficient safety margin in the PWR core. Mitsubishi Heavy Industries, ltd (MHI) is developing a new series of CHF correlations which covers various fuel designs and wide range of fluid conditions with sufficient reliability. In this paper, a new CHF correlation, MG-NV (Mitsubishi Generalized correlation for Non-Vane grid spacers) is presented. This correlation is one of the basic components of the new correlation series and was developed to cover low pressure and low velocity conditions where the rod bundle CHF data are limited. The CHF correlation was developed based on open CHF database and provides conservative but more reliable rod bundle CHF predictions compared with the conventional CHF correlations used in safety analyses at low pressure condition, such as Main Steam Line Break event. (author)

  11. Development of CHF correlation “MG-NV” for low pressure and low velocity conditions applied to PWR safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yumura, T.; Yodo, T.; Makino, Y.; Suemura, T. [Mitsubishi Heavy Industries, LTD., Kobe, Hyogo (Japan)

    2011-07-01

    The Critical Heat Flux (CHF) is one of the important parameters in the safety analysis of Pressurized Water Reactor (PWR). If the CHF is reached, an abrupt drop occurs in the heat transfer between the fuel rod cladding and the reactor coolant, which may induce a large temperature excursion of fuel cladding and a subsequent fuel failure. Therefore, accurate prediction of CHF is required in order to assure a sufficient safety margin in the PWR core. Mitsubishi Heavy Industries, ltd (MHI) is developing a new series of CHF correlations which covers various fuel designs and wide range of fluid conditions with sufficient reliability. In this paper, a new CHF correlation, MG-NV (Mitsubishi Generalized correlation for Non-Vane grid spacers) is presented. This correlation is one of the basic components of the new correlation series and was developed to cover low pressure and low velocity conditions where the rod bundle CHF data are limited. The CHF correlation was developed based on open CHF database and provides conservative but more reliable rod bundle CHF predictions compared with the conventional CHF correlations used in safety analyses at low pressure condition, such as Main Steam Line Break event. (author)

  12. Synchrotron x-ray high energy PDF and tomography studies for gallium melts under high-pressure conditions

    Science.gov (United States)

    Liu, H.; Liu, L. L.; Li, R.; Li, L.

    2015-12-01

    Liquid gallium exhibits unusual and unique physical properties. A rich polymorphism and metastable modifications of solid Ga have been discovered and a number of studies of liquid gallium under high pressure conditions were reported. However, some fundamental properties, such as the equation of state (EoS) of Ga melt under extreme conditions remain unclear. To compare to the previous reports, we performed the pair distribution function (PDF) study using diamond anvil cell, in which synchrotron high-energy x-ray total scattering data, combined with reverse Monte Carlo simulation, was used to study the microstructure and EoS of liquid gallium under high pressure at room temperature conditions. The EoS of Ga melt, which was measured from synchrotron x-ray tomography method at room temperature, was used to avoid the potential relatively big errors for the density estimation from the reverse Monte Carlo simulation with the mathematical fit to the measured structure factor data. The volume change of liquid gallium have been studied as a function of pressure and temperature up to 5 GPa at 370 K using synchrotron x-ray microtomography combined with energy dispersive x-ray diffraction (EDXRD) techniques using Drickamer press. The directly measured P-V-T curves were obtained from 3D tomography reconstruction data. The existence of possible liquid-liquid phase transition regions is proposed based on the abnormal compressibility and local structure change in Ga melts.

  13. 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 wormhole with the ...

  14. Effect of Fe on the Elastic Constants of Magnesiowustite [(Mg,Fe)O] at Ambient Conditions and High Pressure

    Science.gov (United States)

    Sinogeikin, S. V.; Reichmann, H. J.; Bass, J. D.; Mackwell, S. J.; Jacobsen, S. D.

    2001-12-01

    Magnesiowustite is a major mineral in the lower mantle of the Earth. While the effect of temperature and pressure on the elasticity of MgO is well constrained, the effect of Fe on the elastic constants and their pressure derivatives is still uncertain, especially for compositions close to the Mg end-member. Here we present the Brillouin spectroscopy measurements of the single-crystal elastic constants of magnesiowustite at ambient conditions ( ~5.8 mol.% Fe) and to high pressures up to about 10 GPa ( ~1.3 mol.% Fe). The single-crystal samples were prepared by Mg:Fe interdiffusion between periclase single crystals and magnesiowustite powders with carefully controlled oxygen fugacity. The Brillouin scattering measurements were performed in platelet symmetric geometry, which significantly increases the accuracy, and is calibrated with respect to standard periclase sample. High-pressure measurements were performed in a large optical opening Merrill-Basset type diamond anvil cell with Methanol-Ethanol-Water mixture as a pressure-transmitting medium. The new results confirm earlier single-crystal ultrasonic measurements (gigahertz interferometry) which indicated that the behavior of the elastic moduli of magnesiowustite are highly nonlinear in Mg-rich end. A pronounced decrease in acoustic velocities with increasing Fe content is especially obvious in samples with Fe contents of <10 mol. %. The pressure derivatives of the elastic moduli of the sample with XFe = 1.3 mol % are equal to those of periclase within the experimental uncertainties, although the Fe content of the sample may be too small to allow compositional trends to be clearly identified.

  15. Impact of in-sewer transformation on 43 pharmaceuticals in a pressurized sewer under anaerobic conditions

    OpenAIRE

    Jelic, Aleksandra; Rodríguez Mozaz, Sara; Barceló i Cullerés, Damià; Gutiérrez Garcia-Moreno, Oriol

    2015-01-01

    The occurrence of 43 pharmaceuticals and 2 metabolites of ibuprofen was evaluated at the inlet and the outlet of a pressure sewer pipe in order to asses if in-sewer processes affect the pharmaceutical concentrations during their pass through the pipe. The target compounds were detected at concentrations ranging from low ng/L to a few μg/L, which are in the range commonly found in municipal wastewater of the studied area. The changes in concentrations between two sampling points were negligibl...

  16. On the plasma-based growth of ‘flowing’ graphene sheets at atmospheric pressure conditions

    OpenAIRE

    Tsyganov, D.; Bundaleska, N.; Tatarova, E; Dias, A.; Henriques, J; Rego, A.; Ferraria, A.; Abrashev, M. V.; Dias, F. M.; Claudia C. Luhrs; Phillips, Jonathan

    2016-01-01

    The article of record as published may be found at http://dx.doi.org/10.1088/0963-0252/25/1/015013 A theoretical and experimental study on atmospheric pressure microwave plasma-based assembly of free standing graphene sheets is presented. The synthesis method is based on introducing a carbon-containing precursor (C₂H₅OH) through a microwave (2.45 GHz) argon plasma environment, where decomposition of ethanol molecules takes place and carbon atoms and molecules are created and th...

  17. 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.

  18. In Situ Neutron and Synchrotron X-ray Diffraction Studies of Jarosite at High-Temperature High-Pressure Conditions

    Science.gov (United States)

    Xu, H.; Zhao, Y.; Hickmott, D.; Zhang, J.; Vogel, S.; Daemen, L.; Hartl, M.

    2011-03-01

    Jarosite (KFe 3 (SO4)2 (OH)6) occurs in acid mine drainage and epithermal environments and hot springs associated with volcanic activity. Jarosite is also of industrial interest as an iron-impurity extractor from zinc sulfide ores. In 2004, jarosite was detected by the Mars Exploration Rover Mössbauer spectrometer, which has been interpreted as a strong evidence for the existence of water (and possibly life) on ancient Mars. This discovery has spurred considerable interests in stability and structural behavior of jarosite and related phases at various temperature, pressure, and aqueous conditions. In this work, we have investigated the crystal structure and phase stability of jarosite at temperatures up to 900 K and/or pressures up to 9 GPa using in situ neutron and synchrotron X-ray diffraction. To avoid the large incoherent scattering of neutrons by hydrogen, a deuterated sample was synthesized and characterized. Rietveld analysis of the obtained diffraction data allowed determination of unit-cell parameters, atomic positions and atomic displacement parameters as a function of temperature and pressure. In addition, the coefficients of thermal expansion, bulk moduli and pressure-temperature stability regions of jarosite were determined.

  19. Pressure measurements and high speed visualizations of the cavitation phenomena at deep part load condition in a Francis turbine

    Science.gov (United States)

    Yamamoto, K.; Müller, A.; Favrel, A.; Landry, C.; Avellan, F.

    2014-03-01

    In a hydraulic power plant, it is essential to provide a reliable, sustainable and flexible energy supply. In recent years, in order to cover the variations of the renewable electricity production, hydraulic power plants are demanded to operate with more extended operating range. Under these off-design conditions, a hydraulic turbine is subject to cavitating swirl flow at the runner outlet. It is well-known that the helically/symmetrically shaped cavitation develops at the runner outlet in part load/full load condition, and it gives severe damage to the hydraulic systems under certain conditions. Although there have been many studies about partial and full load conditions, contributions reporting the deep part load condition are limited, and the cavitation behaviour at this condition is not yet understood. This study aims to unveil the cavitation phenomena at deep part load condition by high speed visualizations focusing on the draft tube cone as well as the runner blade channel, and pressure fluctuations associated with the phenomena were also investigated.

  20. 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)

  1. Effective diffusion coefficients of gas mixture in heavy oil under constant-pressure conditions

    Science.gov (United States)

    Li, Huazhou Andy; Sun, Huijuan; Yang, Daoyong

    2016-09-01

    We develop a method to determine the effective diffusion coefficient for each individual component of a gas mixture in a non-volatile liquid (e.g., heavy oil) at high pressures with compositional analysis. Theoretically, a multi-component one-way diffusion model is coupled with the volume-translated Peng-Robinson equation of state to quantify the mass transfer between gas and liquid (e.g., heavy oil). Experimentally, the diffusion tests have been conducted with a PVT setup for one pure CO2-heavy oil system and one C3H8-CO2-heavy oil system under constant temperature and pressure, respectively. Both the gas-phase volume and liquid-phase swelling effect are simultaneously recorded during the measurement. As for the C3H8-CO2-heavy oil system, the gas chromatography method is employed to measure compositions of the gas phase at the beginning and end of the diffusion measurement, respectively. The effective diffusion coefficients are then determined by minimizing the discrepancy between the measured and calculated gas-phase composition at the end of diffusion measurement. The newly developed technique can quantify the contributions of each component of mixture to the bulk mass transfer from gas into liquid. The effective diffusion coefficient of C3H8 in the C3H8-CO2 mixture at 3945 ± 20 kPa and 293.85 K, i.e., 18.19 × 10^{ - 10} m^{ 2} / s, is found to be much higher than CO2 at 3950 ± 18 kPa and 293.85 K, i.e., 8.68 × 10^{ - 10} m^{ 2} / s. In comparison with pure CO2, the presence of C3H8 in the C3H8-CO2 mixture contributes to a faster diffusion of CO2 from the gas phase into heavy oil and consequently a larger swelling factor of heavy oil.

  2. Pavlovian conditioning of corticotropin-releasing factor-induced increase of blood pressure and corticosterone secretion in the rat.

    Science.gov (United States)

    Kreutz, M; Hellhammer, D; Murison, R; Vetter, H; Krause, U; Lehnert, H

    1992-05-01

    Corticotropin-releasing factor (CRF) is clearly involved in the central regulation of the pituitary-adrenal axis and, moreover, of autonomic nervous system functions. Enhanced sympathetic activity with subsequent increases in blood pressure and heart rate and attenuation of the baroreceptor reflex results from the intracerebroventricular (i.c.v.) administration of CRF. Additionally, the peptide has a variety of potent effects on behavioural responses in animals similar to those observed after an experimentally evoked stress. It was therefore of obvious interest to examine whether CRF is a possible mediator of the learning processes associated with physiological stress reaction patterns. This report clearly demonstrates a classical conditioning of the endocrine (i.e. corticosterone secretion) and haemodynamic (i.e. blood pressure) sequelae following central CRF application and thus indicates that this mechanism is of physiological significance for learned stress responses.

  3. Study of Pt Addition Under Simulated Primary Circuit Condition of Pressurized Water Reactor

    Institute of Scientific and Technical Information of China (English)

    HAI; Zheng-yin; WANG; Hui; CAO; Lin-yuan; HU; Yong

    2013-01-01

    The method of Pt addition under simulated PWR hydrogen water chemistry(HWC)condition and its effects on the electrochemical behavior of structural material 316LN were studied by SEM,XPS,XRD,ICP-AES and linear dynamic polarization etc.At first,all test samples were exposed in 320℃high

  4. Ambient-condition growth of high-pressure phase centrosymmetric crystalline KDP microstructures for optical second harmonic generation.

    Science.gov (United States)

    Ren, Yan; Zhao, Xian; Hagley, Edward W; Deng, Lu

    2016-08-01

    Noncentrosymmetric potassium dihydrogen phosphate (KH2PO4 or KDP) in the tetragonal crystal phase is arguably the most extensively studied nonlinear optical crystal in history. It has prolific applications ranging from simple laser pointers to laser inertial confinement fusion systems. Recently, type IV high-pressure KDP crystal sheets with a monoclinic crystal phase having centrosymmetric properties have been observed. However, it was found that this new crystal phase is highly unstable under ambient conditions. We report ambient-condition growth of one-dimensional, self-assembled, single-crystalline KDP hexagonal hollow/solid-core microstructures that have a molecular structure and symmetry identical to the type IV KDP monoclinic crystal that was previously found to exist only at extremely high pressures (>1.6 GPa). Furthermore, we report highly efficient bulk optical second harmonic generation (SHG) from these ambient condition-grown single-crystalline microstructures, even though they have a highly centrosymmetric crystal phase. However, fundamental physics dictates that a bulk optical medium with a significant second-order nonlinear susceptibility supporting SHG must have noncentrosymmetric properties. Laue diffraction analysis reveals a weak symmetry-breaking twin-crystal lattice that, in conjunction with tight confinement of the light field by the tubular structure, is attributed to the significant SHG even with sample volumes <0.001 mm(3). A robust polarization-preserving effect is also observed, raising the possibility of advanced optical technological applications. PMID:27574703

  5. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish

    2016-09-08

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

  6. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L.; Cha, Min Suk

    2016-10-01

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface.

  7. Impact of in-sewer transformation on 43 pharmaceuticals in a pressurized sewer under anaerobic conditions.

    Science.gov (United States)

    Jelic, Aleksandra; Rodriguez-Mozaz, Sara; Barceló, Damia; Gutierrez, Oriol

    2015-01-01

    The occurrence of 43 pharmaceuticals and 2 metabolites of ibuprofen was evaluated at the inlet and the outlet of a pressure sewer pipe in order to asses if in-sewer processes affect the pharmaceutical concentrations during their pass through the pipe. The target compounds were detected at concentrations ranging from low ng/L to a few μg/L, which are in the range commonly found in municipal wastewater of the studied area. The changes in concentrations between two sampling points were negligible for most compounds, i.e. from -10 to 10%. A higher decrease in concentrations (25-60 %) during the pass through the pipe was observed for diltiazem, citalopram, clarithromycin, bezafibrate and amlodipine. Negative removal was calculated for sulfamethoxazole (-66 ± 15%) and irbesartan (-58 ± 25%), which may be due to the conversion of conjugates back to their parent compounds in the sewer. The results show that microbial transformation of pharmaceuticals begins in sewer, albeit to different extents for different compounds. Therefore, the in-sewer transformation of pharmaceuticals should be assessed especially when their concentrations are used to estimate and refine the estimation of their per capita consumption in a catchment of interest in the sewage epidemiology approach. PMID:25462720

  8. 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...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems.......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...

  9. On the plasma-based growth of ‘flowing’ graphene sheets at atmospheric pressure conditions

    Science.gov (United States)

    Tsyganov, D.; Bundaleska, N.; Tatarova, E.; Dias, A.; Henriques, J.; Rego, A.; Ferraria, A.; Abrashev, M. V.; Dias, F. M.; Luhrs, C. C.; Phillips, J.

    2016-02-01

    A theoretical and experimental study on atmospheric pressure microwave plasma-based assembly of free standing graphene sheets is presented. The synthesis method is based on introducing a carbon-containing precursor (C2H5OH) through a microwave (2.45 GHz) argon plasma environment, where decomposition of ethanol molecules takes place and carbon atoms and molecules are created and then converted into solid carbon nuclei in the ‘colder’ nucleation zones. A theoretical model previously developed has been further updated and refined to map the particle and thermal fluxes in the plasma reactor. Considering the nucleation process as a delicate interplay between thermodynamic and kinetic factors, the model is based on a set of non-linear differential equations describing plasma thermodynamics and chemical kinetics. The model predictions were validated by experimental results. Optical emission spectroscopy was applied to detect the plasma emission related to carbon species from the ‘hot’ plasma zone. Raman spectroscopy, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS) techniques have been applied to analyze the synthesized nanostructures. The microstructural features of the solid carbon nuclei collected from the colder zones of plasma reactor vary according to their location. A part of the solid carbon was deposited on the discharge tube wall. The solid assembled from the main stream, which was gradually withdrawn from the hot plasma region in the outlet plasma stream directed to a filter, was composed by ‘flowing’ graphene sheets. The influence of additional hydrogen, Ar flow rate and microwave power on the concentration of obtained stable species and carbon-dicarbon was evaluated. The ratio of sp3/sp2 carbons in graphene sheets is presented. A correlation between changes in C2 and C number densities and sp3/sp2 ratio was found.

  10. Characterisation of Brachycephalic Obstructive Airway Syndrome in French Bulldogs Using Whole-Body Barometric Plethysmography.

    Directory of Open Access Journals (Sweden)

    Nai-Chieh Liu

    Full Text Available Brachycephalic obstructive airway syndrome (BOAS is an important health and welfare problem in several popular dog breeds. Whole-body barometric plethysmography (WBBP is a non-invasive method that allows safe and repeated quantitative measurements of respiratory cycles on unsedated dogs. Here respiratory flow traces in French bulldogs from the pet population were characterised using WBBP, and a computational application was developed to recognise affected animals. Eighty-nine French bulldogs and twenty non-brachycephalic controls underwent WBBP testing. A respiratory functional grading system was used on each dog based on respiratory signs (i.e. respiratory noise, effort, etc. before and after exercise. For development of an objective BOAS classifier, functional Grades 0 and I were considered to have insignificant clinical signs (termed here BOAS- and Grades II and III to have significant signs (termed here BOAS+. A comparison between owner-perception of BOAS and functional grading revealed that 60 % of owners failed to recognise BOAS in dogs that graded BOAS+ in this study.WBBP flow traces were found to be significantly different between non-brachycephalic controls and Grade 0 French bulldogs; BOAS- and BOAS+ French bulldogs. A classifier was developed using quadratic discriminant analysis of the respiratory parameters to distinguish BOAS- and BOAS + French bulldogs, and a BOAS Index was calculated for each dog. A cut-off value of the BOAS Index was selected based on a receiver operating characteristic (ROC curve. Sensitivity, specificity, positive predictive value, and negative predictive value of the classifier on the training group (n=69 were 0.97, 0.93, 0.95, and 0.97, respectively. The classifier was validated using a test group of French bulldogs (n=20 with an accuracy of 0.95. WBBP offers objective screening for the diagnosis of BOAS in French Bulldogs. The technique may be applied to other brachycephalic breeds affected by BOAS, and

  11. Laboratory measurements of materials in extreme conditions; The use of high energy radiation sources for high pressure studies

    Energy Technology Data Exchange (ETDEWEB)

    Cauble, R.; Remington, B.A.

    1998-06-01

    High energy lasers can be used to study material conditions that are appropriate fort inertial confinement fusion: that is, materials at high densities, temperatures, and pressures. Pulsed power devices can offer similar opportunities. The National Ignition Facility (NIF) will be a high energy multi-beam laser designed to achieve the thermonuclear ignition of a mm-scale DT-filled target in the laboratory. At the same time, NE will provide the physics community with a unique tool for the study of high energy density matter at states unreachable by any other laboratory technique. Here we describe how these lasers and pulsed power tools can contribute to investigations of high energy density matter in the areas of material properties and equations of state, extend present laboratory shock techniques such as high-speed jets to new regimes, and allow study of extreme conditions found in astrophysical phenomena.

  12. 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

  13. Carbonation by fluid-rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

    Science.gov (United States)

    Piccoli, Francesca; Vitale Brovarone, Alberto; Beyssac, Olivier; Martinez, Isabelle; Ague, Jay J.; Chaduteau, Carine

    2016-07-01

    Carbonate-bearing lithologies are the main carbon carrier into subduction zones. Their evolution during metamorphism largely controls the fate of carbon, regulating its fluxes between shallow and deep reservoirs. Recent estimates predict that almost all subducted carbon is transferred into the crust and lithospheric mantle during subduction metamorphism via decarbonation and dissolution reactions at high-pressure conditions. Here we report the occurrence of eclogite-facies marbles associated with metasomatic systems in Alpine Corsica (France). The occurrence of these marbles along major fluid-conduits as well as textural, geochemical and isotopic data indicating fluid-mineral reactions are compelling evidence for the precipitation of these carbonate-rich assemblages from carbonic fluids during metamorphism. The discovery of metasomatic marbles brings new insights into the fate of carbonic fluids formed in subducting slabs. We infer that rock carbonation can occur at high-pressure conditions by either vein-injection or chemical replacement mechanisms. This indicates that carbonic fluids produced by decarbonation reactions and carbonate dissolution may not be directly transferred to the mantle wedge, but can interact with slab and mantle-forming rocks. Rock-carbonation by fluid-rock interactions may have an important impact on the residence time of carbon and oxygen in subduction zones and lithospheric mantle reservoirs as well as carbonate isotopic signatures in subduction zones. Furthermore, carbonation may modulate the emission of CO2 at volcanic arcs over geological time scales.

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

    Energy Technology Data Exchange (ETDEWEB)

    Herbschleb, C. T.; Tuijn, P. C. van der; Roobol, S. B.; Navarro, V.; Bakker, J. W.; Liu, Q.; Stoltz, D.; Cañas-Ventura, M. E.; Verdoes, G.; Spronsen, M. A. van; Bergman, M.; Crama, L.; Taminiau, I.; Frenken, J. W. M., E-mail: frenken@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. box 9504, 2300 RA Leiden (Netherlands); Ofitserov, A.; Baarle, G. J. C. van [Leiden Probe Microscopy B.V., J.H. Oortweg 21, 2333 CH Leiden (Netherlands)

    2014-08-15

    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.

  15. Mid-crustal shear zone development under retrograde conditions: pressure-temperature-fluid constraints from the Kuckaus Mylonite Zone, Namibia

    Science.gov (United States)

    Diener, Johann F. A.; Fagereng, Åke; Thomas, Sukey A. J.

    2016-09-01

    The Kuckaus Mylonite Zone (KMZ) forms part of the larger Marshall Rocks-Pofadder shear zone system, a 550 km-long, crustal-scale strike-slip shear zone system that is localized in high-grade granitoid gneisses and migmatites of the Namaqua Metamorphic Complex. Shearing along the KMZ occurred ca. 40 Ma after peak granulite-facies metamorphism during a discrete tectonic event and affected the granulites that had remained at depth since peak metamorphism. Isolated lenses of metamafic rocks within the shear zone allow the P-T-fluid conditions under which shearing occurred to be quantified. These lenses consist of an unsheared core that preserves relict granulite-facies textures and is mantled by a schistose collar and mylonitic envelope that formed during shearing. All three metamafic textural varieties contain the same amphibolite-facies mineral assemblage, from which calculated pseudosections constrain the P-T conditions of deformation at 2.7-4.2 kbar and 450-480 °C, indicating that deformation occurred at mid-crustal depths through predominantly viscous flow. Calculated T-MH2O diagrams show that the mineral assemblages were fluid saturated and that lithologies within the KMZ must have been rehydrated from an external source and retrogressed during shearing. Given that the KMZ is localized in strongly dehydrated granulites, the fluid must have been derived from an external source, with fluid flow allowed by local dilation and increased permeability within the shear zone. The absence of pervasive hydrothermal fractures or precipitates indicates that, even though the KMZ was fluid bearing, the fluid/rock ratio and fluid pressure remained low. In addition, the fluid could not have contributed to shear zone initiation, as an existing zone of enhanced permeability is required for fluid infiltration. We propose that, following initiation, fluid infiltration caused a positive feedback that allowed weakening and continued strain localization. Therefore, the main

  16. Boron: a frustrated element. Physical properties at ambient conditions and under pressure from ab-initio calculations

    Science.gov (United States)

    Ogitsu, Tadashi; Gygi, Francois; Galli, Giulia

    2004-03-01

    Boron is the only low-Z element in the periodic table whose atomic ground state structure has not yet been fully determined. For example, it is yet unclear whether perfectly pure elemental Boron is stable in an ordered crystalline form and the number of atoms in the unit cell (varying from 315 to about 325) is still the subject of debate. Using ab-initio calculations and supercells with 1260-1280 atoms, we have studied the physical properties of Boron at ambient conditions and under pressure (P). Results about the ionic and electronic structure will be presented, in particular the role of interstitial atoms and the presence of localized states right above the Fermi level will be discussed in detail. The computed equation of state under pressure is in agreement with recent experimental data. At about 120 GPa we observe amorphization, consistent with the results of Ref. [1] at l00 GPa. Amorphization occurs by random deformation of icosahedral units which remain intact; it is accompanied by a delocalization of states near the Fermi level yielding a poorly conducting system. This work was performed under the auspices of the U.S. Dept. of Energy at the University of California/ LLNL under contract no. W-7405-Eng-48. [1] Sanz et al. Phys. Rev. Lett. 89, 245501 (2002)

  17. 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.

  18. Selection of instruments used for vibration measurement of fuel bundles in a pressure tube under CANDU reactor operating conditions

    International Nuclear Information System (INIS)

    Vibration characteristics of CANDU fuel bundle and fuel elements is a key parameter considered in the design of a fuel bundle. Out-reactor frequency and temperature sweep tests, under reactor operating conditions, are performed to verify vibration characteristics of CANDU fuel bundles. Several options have been considered in the selection of vibration instrumentation to perform out-reactor frequency and temperature sweep tests. This paper compares the benefits and disadvantages of various vibration instruments and summarizes the rationale behind the selection of instruments used for vibration measurements over a range of temperature and pressure pulsation frequencies. The conclusions are presented from the bench tests performed, which confirm the use of the selected instruments. (author)

  19. Effects of Mg on diamond growth and properties in Fe-C system under high pressure and high temperature condition

    Science.gov (United States)

    Huang, Guo-Feng; Zheng, You-Jin; Li, Zhan-Chang; Gao, Qiang; Ma, Zhuo; Shi, Si-Ming; Jiang, Bao-Gang; Zhao, He

    2016-08-01

    Diamond crystal crystallized in Fe-Mg-C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of the Mg element results in the nitrogen concentration increasing from 87 ppm to 271 ppm in the diamond structure. The occurrence of the {100} plane reveals that the surface character is remarkably changed due to the addition of Mg. Micro-Raman spectra indicate that the half width of full maximum is in a range of 3.01 cm-1-3.26 cm-1, implying an extremely good quality of diamond specimens in crystallization. Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region, China (Grant No. 2013MS0809) and the Open Project of Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University) of the Ministry of Education of China (Grant No. 201608).

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

    Institute of Scientific and Technical Information of China (English)

    Hu Mei-Hua; Li Shang-Sheng; Ma Hong-An; Su Tai-Chao; Li Xiao-Lei; Hu Qiang; Jia Xiao-Peng

    2012-01-01

    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.

  1. Effects of Mg on diamond growth and properties in Fe–C system under high pressure and high temperature condition

    Science.gov (United States)

    Huang, Guo-Feng; Zheng, You-Jin; Li, Zhan-Chang; Gao, Qiang; Ma, Zhuo; Shi, Si-Ming; Jiang, Bao-Gang; Zhao, He

    2016-08-01

    Diamond crystal crystallized in Fe–Mg–C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of the Mg element results in the nitrogen concentration increasing from 87 ppm to 271 ppm in the diamond structure. The occurrence of the {100} plane reveals that the surface character is remarkably changed due to the addition of Mg. Micro-Raman spectra indicate that the half width of full maximum is in a range of 3.01 cm‑1–3.26 cm‑1, implying an extremely good quality of diamond specimens in crystallization. Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region, China (Grant No. 2013MS0809) and the Open Project of Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University) of the Ministry of Education of China (Grant No. 201608).

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

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; JIA Peng-Ying; ZHAO Na

    2011-01-01

    @@ 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.%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.

  3. 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

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

    Science.gov (United States)

    Perrier, Frédéric; Richon, Patrick

    2010-04-01

    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. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P.; Ritter, S

    2002-02-01

    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)

  6. 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)

  7. Radiolysis of water at high temperature and pressure conditions: a picosecond pulse radiolysis experiment and numerical simulations

    International Nuclear Information System (INIS)

    Radiolytic products of coolant material under strong radiation field in water-cooled reactors are known to give undesirable effects on nuclear structural materials. Understanding of the fundamental processes will be of great importance for various application fields in water chemistry. Ionization and excitation of water molecules by ionizing radiations initiate very fast physical and chemical processes within μs(10-6 sec), ns (10-9 sec) or even ps (10-12 sec), followed by formation of primary radiolytic species (e-aq, OH, H, H2, H2O2 etc.). Through the processes, the radiation chemical yields (G-values) are supposed to change dynamically depending on time and also on temperature. However, because of so high reactivity (short lifetime), it was difficult to observe experimentally the temporal behaviors (spatially inhomogeneous reactions, called spur diffusion reactions). In this work, the fundamental processes (G-values of the intermediates and the fast reaction kinetics) of the radiolysis of water at high temperature and pressure conditions (HTHP) were investigated by a newly developed picosecond time-resolved pulse radiolysis system, and also by numerical analyses. The results indicated that the hydrated electron (e-aq) in the spur reaction process mainly reacts with OH at room temperature, while that with H3O+ becomes also competitive in subcritical water. Taking the cumulative yield variations (ΔG molec./100eV) into account, it is suggested that historically defined primary G-value of the hydrated electron in subcritical water (G ∼ 3.6 molec./100eV) will be appropriately reexamined to the lower value below 2.7 in neutral pH condition, while it is rather close to it in basic condition. (author)

  8. conditions

    Directory of Open Access Journals (Sweden)

    M. Venkatesulu

    1996-01-01

    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.

  9. Reactive molecular dynamics study of Mo-based alloys under high-pressure, high-temperature conditions

    Science.gov (United States)

    Vasenkov, Alex; Newsome, David; Verners, Osvalds; Russo, Michael F.; Zaharieva, Roussislava; van Duin, Adri C. T.

    2012-07-01

    Structural metal alloys are of vital importance for a clean energy economy, but the current trial-and-error alloy development methodology is expensive and time consuming. In this study, we demonstrate the capability of the ReaxFF force field model to predict mechanical properties and provide a fully dynamic description of oxidation and sulfidation of Mo-based alloys under high-pressure, high-temperature conditions using molecular dynamics (MD) method. The advantage of the ReaxFF approach is in its ability to model the formation and breaking of chemical bonds within the quantum framework but several orders of magnitude faster than the traditional density functional theory models. ReaxFF-MD predictions were compared to the literature Mo shock compression measurements at 300 K and 1673 K in the pressure range of 0-350 Pa, and densities and Young's modulus in the temperature range of 300-1500 K. Analysis of oxidation of Mo and Ni clusters and surface slabs showed that Mo oxidation proceeded at a significantly higher rate than the Ni oxidation and involved oxygen transport inside the metal cluster coupled to large heat release that caused extensive surface melting. The oxidation simulations of Mo3Ni clusters showed high production of Mo oxides and a low concentration of Ni-oxides in the gas phase. This was attributed to the higher chemical stability of Mo-oxide gas phase species. Modeling of H2S interactions with Mo slab demonstrated that sulfur atoms increasingly agglomerated in the surfaces layers of the slab as the simulation proceeded, diffusing deeper into the slab in their atomic forms. A combined ReaxFF Mo/Ni/C/O/N/S/H parameter set enabled us to obtain a detailed atomistic analysis of complex physical and chemical events during the combustion of a complex fuel molecule on a reactor surface.

  10. 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

  11. 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

  12. The ReactorAFM: Non-contact atomic force microscope operating under high-pressure and high-temperature catalytic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Roobol, S. B.; Cañas-Ventura, M. E.; Bergman, M.; Spronsen, M. A. van; Onderwaater, W. G.; Tuijn, P. C. van der; Koehler, R.; Frenken, J. W. M., E-mail: frenken@arcnl.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, RA Leiden 2300 (Netherlands); Ofitserov, A.; Baarle, G. J. C. van [Leiden Probe Microscopy B.V., J.H. Oortweg 21, 2333 CH Leiden (Netherlands)

    2015-03-15

    An Atomic Force Microscope (AFM) has been integrated in a miniature high-pressure flow reactor for in-situ observations of heterogeneous catalytic reactions under conditions similar to those of industrial processes. The AFM can image model catalysts such as those consisting of metal nanoparticles on flat oxide supports in a gas atmosphere up to 6 bar and at a temperature up to 600 K, while the catalytic activity can be measured using mass spectrometry. The high-pressure reactor is placed inside an Ultrahigh Vacuum (UHV) system to supplement it with standard UHV sample preparation and characterization techniques. To demonstrate that this instrument successfully bridges both the pressure gap and the materials gap, images have been recorded of supported palladium nanoparticles catalyzing the oxidation of carbon monoxide under high-pressure, high-temperature conditions.

  13. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors

    OpenAIRE

    Feddema, Rick Thomas

    2013-01-01

    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...

  14. 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.

  15. Numerical investigation of the spray-mesh-turbulence interactions for high-pressure, evaporating sprays at engine conditions

    International Nuclear Information System (INIS)

    This work presents a numerical methodology to simulate evaporating, high pressure Diesel sprays using the Eulerian-Lagrangian approach. Specific sub-models were developed to describe the liquid spray injection and breakup, and the influence of the liquid jet on the turbulence viscosity in the vicinity of the nozzle. To reduce the computational time and easily solve the problem of the grid dependency, the possibility to dynamically refine the grid where the fuel-air mixing process takes place was also included. The validity of the proposed approach was firstly verified simulating an evaporating spray in a constant-volume vessel at non-reacting conditions. The availability of a large quantity of experimental data allowed us to investigate in detail the effects of grid size, ambient diffusivity and used spray sub-models. In this way, different guidelines were derived for a successful simulation of the fuel-air mixture formation process. Finally, fuel injection and evaporation were simulated in an optical engine geometry and computed mixture fraction distributions were compared with experimental data.

  16. Black tea lowers blood pressure and wave reflections in fasted and postprandial conditions in hypertensive patients: a randomised study.

    Science.gov (United States)

    Grassi, Davide; Draijer, Richard; Desideri, Giovambattista; Mulder, Theo; Ferri, Claudio

    2015-02-04

    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 (ptea consumption (pBlack tea decreased systolic and diastolic BP (-3.2 mmHg, pBlack 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.

  17. 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.

  18. Mechanical and thermal properties of γ-Mg2SiO4 under high temperature and high pressure conditions such as in mantle: A first principles study.

    Science.gov (United States)

    Feng, Xing; Xiao, Jianwei; Melnik, Roderick; Kawazoe, Yoshiyuki; Wen, Bin

    2015-09-14

    γ-Mg2SiO4 is an important mineral in mantle, and our knowledge on its mechanical and thermal properties is critical for many areas of geological sciences. In this work, the crystal structure of γ-Mg2SiO4 under high temperature and high pressure conditions is optimized by using the GOMASC method, and the total energy, thermal expansion coefficients, and elastic constants at different temperature and pressure conditions are obtained. On the basis of phonon spectrum, group velocity, phase velocity, Grüneisen parameter, and thermal conductivity are calculated for γ-Mg2SiO4 under high temperature and high pressure conditions. These calculated results can provide an important reference for geological research. PMID:26374046

  19. Mineralogía y termo-barometría de los Complejos máficos Sol de Mayo y Suya Taco, Norte de las Sierras de Comechingones, Córdoba Mineralogy and thermo-barometry of the Sol de Mayo and Suya Taco mafic complexes from northern Sierra de Comechingones, Córdoba

    Directory of Open Access Journals (Sweden)

    Alina M. Tibaldi

    2008-03-01

    the latter method may be not applicable to rocks crystallized from Fe-rich magmas. Amphibole-plagioclase thermometry estimates, which use typical core compositions, yield equilibrium temperature in the range of 750-850ºC. Whereas using rim compositions, Amph-pl thermometry estimates significantly give lower temperatures (< 600ºC, suggesting that amphiboles mostly crystallized at post-magmatic stages. Orthopyroxene-biotite Fe-Mg exchange thermometry shows that these minerals tend to equilibrate within two distinct thermal ranges (430-650ºC and 740-1030ºC. This indicates that biotites might have crystallized at both late-magmatic and post-magmatic stages. Barometric estimates have some variability in function of the type of calibration used, however they show a systematic pattern in which the equilibrium pressure determined in the Suya Taco complex are lower (5.5 ± 1 kbar than those obtained in the Sol de Mayo complex (8 ± 1 kbar. Overall, this result is consistent with barometry already performed in granulitic xenoliths. The P-T conditions deduced from igneous rocks indicate that the hosting regional metasedimentary sequence were experiencing amphibolite-facies temperatures and residing at middle crustal levels.

  20. 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

  1. 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

  2. The effects of melatonin on anxiety and pain scores of patients, intraocular pressure, and operating conditions during cataract surgery under topical anesthesia

    Directory of Open Access Journals (Sweden)

    Marzieh Beigom Khezri

    2013-01-01

    Full Text Available Aims: To evaluate the effects of melatonin premedication on anxiety and pain scores of patients, operating conditions, and intraocular pressure during cataract surgery under topical anesthesia. Materials and Methods: Sixty patients were randomly assigned to receive either sublingual melatonin 3 mg or placebo 60 min before surgery. Verbal anxiety scores and verbal pain scores, heart rate, systolic and diastolic blood pressure, intraocular pressure, and quality of operating conditions were recorded. Results: Melatonin significantly reduced the anxiety scores (median, interquartile range from 5 and 5-3 to 3 and 2-4 after premedication and to 3 and 2-3 during surgery and to 0 and 0-1 postoperatively before discharge from the recovery room. There were significant differences between two groups in anxiety scores after premedication (95% CI 3-3.5; P = 0.023, intraoperatively (95% CI 2.5-3.5; P = 0.007, and postoperatively (95% CI 0.5-1; P = 0.007. The surgeon reported better quality of operating conditions in the melatonin group (P = 0.001. No significant difference in intraoperative and postoperative pain scores, intraocular pressure, heart rate, and systolic and diastolic blood pressure between two groups was recorded. Conclusion: Sublingual melatonin premedication for patients undergoing cataract surgery under topical anesthesia reduced the anxiety scores in patients and provided excellent operating conditions.

  3. 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 paramet......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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Cartin, L.R.; Winks, R.W.; Merchent, J.W.; Brandt, R.T.

    1982-12-01

    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).

  5. In situ XFEL measurement system for Earth and planetary materials under laser-induced ultrahigh-pressure conditions

    Science.gov (United States)

    Tange, Y.; Ozaki, N.; Matsuoka, T.; Ogawa, T.; Albertazzi, B.; Habara, H.; Takahashi, K.; Matsuyama, S.; Yamauchi, K.; Tanaka, K.; Kodama, R.; Sato, T.; Sekine, T.; Seto, Y.; Okuchi, T.; Yabuuchi, T.; Inubushi, Y.; Yabashi, M.

    2015-12-01

    High-pressure and high-temperature in situ experiments have revealed behaviors of the earth and planetary constituents under extreme conditions, and contribute to progress our understandings about physical and chemical structure of planetary interiors. These in situ techniques have developed with the third-generation synchrotron radiation facilities such as APS, ESRF, and SPring-8 mainly using large volume presses and diamond anvil cells. In addition to the synchrotron light source, recently X-ray free electron laser (XFEL) facilities have been developed as LCLS and SACLA. The brilliant and extremely short-pulsed XFELs make it possible to carry out femto-second time-resolve measurements, and to observe materials under dynamic/shock compression clearly. Techniques using high-power laser and XFEL are expected to be a next-generation experimental platform, and a pump-probe measurement system using high-power lasers and XFEL was installed at BL3EH5 in SPring-8/SACLA interoperable experimental facility. The system is composed of 45 TW X-ray focusing system (KB mirrors), vacuumed sample chamber, and the MPCCD detector developed for the 10-fs ultra-short pulsed XFEL light source. The high-power laser enables us to generate up to 100 GPa for metal, simple oxide, and natural/synthesized mineral samples. Samples are mounted on sample holders and aligned at the center of the vacuum chamber using a 4-axis Goniometer head. In this presentation, we will overview the experimental setups and typical results of current pump-probe system using XFEL in SACLA.

  6. A Study on Variations of the Low Cycle Fatigue Life of a High Pressure Turbine Nozzle Caused by Inlet Temperature Profiles and Installation Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Jae Sung; Kang, Young Seok; Rhee, Dong Ho [Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Seo, Do Young [Pusan National Univ., Busan (Korea, Republic of)

    2015-11-15

    High pressure components of a gas turbine engine must operate for a long life under severe conditions in order to maximize the performance and minimize the maintenance cost. Enhanced cooling design, thermal barrier coating techniques, and nickel-base superalloys have been applied for overcoming them and furthermore, material modeling, finite element analysis, statistical techniques, and etc. in design stage have been utilized widely. This article aims to evaluate the effects on the low cycle fatigue life of the high pressure turbine nozzle caused by different turbine inlet temperature profiles and installation conditions and to investigate the most favorable operating condition to the turbine nozzle. To achieve it, the structural analysis, which utilized the results of conjugate heat transfer analysis as loading boundary conditions, was performed and its results were the input for the assessment of low cycle fatigue life at several critical zones.

  7. A study on variations of the low cycle fatigue life of a high pressure turbine nozzle caused by inlet temperature profiles and installation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Jae Sung; Kang, Young Seok; Rhee, Dong Ho [Aero-propulsion Research Office, Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Seo, Do Young [School of Mechanical and Aerospace Engineering, Pusan National University, Busan (Korea, Republic of)

    2015-11-15

    High pressure components of a gas turbine engine must operate for a long life under severe conditions in order to maximize the performance and minimize the maintenance cost. Enhanced cooling design, thermal barrier coating techniques, and nickel-base superalloys have been applied for overcoming them and furthermore, material modeling, finite element analysis, statistical techniques, and etc. in design stage have been utilized widely. This article aims to evaluate the effects on the low cycle fatigue life of the high pressure turbine nozzle caused by different turbine inlet temperature profiles and installation conditions and to investigate the most favorable operating condition to the turbine nozzle. To achieve it, the structural analysis, which utilized the results of conjugate heat transfer analysis as loading boundary conditions, was performed and its results were the input for the assessment of low cycle fatigue life at several critical zones.

  8. 鱼肉肠的超高压杀菌工艺研究%Study on Ultra- high Pressure Sterilization Conditions for Fish Sausage

    Institute of Scientific and Technical Information of China (English)

    杭瑜瑜

    2012-01-01

    Ultra - high pressure sterilization conditions for fish sausage were studied. The effect of different processing pressure, temperature and holding time on survival of microorganisms of fish sausage was investigated, The Sterilization conditions was optimized by using orthogonal test design. The optimum condition for sterilizing fish sausage was determined to be 400MPa,30℃ and 5rain.%以鱼肉肠为研究对象考察了处理压力、保压时间以及协同温度对微生物的影响,并采用正交试验优化了鱼肉肠的杀菌工艺条件.通过数据分析得出杀菌的最优化工艺条件为:操作压力400MPa、保压时间5min、协同温度30℃.

  9. Axial gas transport and loss of pressure after ballooning rupture of high burn-up fuel rods subjected to LOCA conditions

    International Nuclear Information System (INIS)

    The OECD Halden Reactor Project has implemented integral in-pile tests on issues related to fuel behaviour under LOCA conditions. In this test series, the interaction of bonded fuel and cladding, the behaviour of fragmented fuel around the ballooning area, and the axial gas communication in high burn-up rods as affected by gap closure and fuel-clad bonding are of major interest for the investigations. In the Halden reactor tests, the decay heat is simulated by a low level of nuclear heating, in contrast to the heating conditions implemented in hot laboratory set-ups, and the thermal expansion of fuel and cladding relative to each other is more similar to the real event. The paper deals with observations regarding the loss of rod pressure following the rupture of the cladding. In the majority of the tests conducted so far, the rod pressure dropped practically instantaneously as a consequence of ballooning rupture, while one test showed a remarkably slow pressure loss. The slow loss of pressure in this test was analysed, showing that the 'hydraulic diameter' of the rod over an un-distended upper part was about 30 - 35 μm which is typical of high burn-up fuel at hot-standby conditions. The 'plug' of fuel restricts the gas flow from the plenum through the fuel column and thus limits the availability of high pressure gas for driving the ballooning. This observation is relevant for the analysis of the behaviour of a full length fuel rod under LOCA conditions since restricted gas flow may influence bundle blockage and the number of failures. (authors)

  10. A new experimental setup for the liquid-solid phase transition determination in crude oils under high pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    A. Rizzo; H. Carrier; J. Castillo; S. Acevedo; J. Pauly [UNEXPO - Vicerectorado Barquisimeto (Venezuela). Departamento de Ingeniera Quimica

    2007-08-15

    A high pressure apparatus based on two sapphire windows high pressure cell coupled with a detection system of the reflected and refracted light intensities coming from a laser beam was designed to determine the phase transitions by the measurement of the light intensity change. The setup was used to measure the wax disappearance temperature under pressure up to 100 MPa in pure component, synthetic complex mixtures made up of distributions of n-paraffins ranging from n-C{sub 20} to n-C{sub 42}. Finally a real stabilized condensate was successfully investigated and the sensitivity of the detection system was demonstrated on a dark crude oil. 30 refs., 10 figs., 1 tab.

  11. The dynamics crossover region in phenol- and cresol-phthalein-dimethylethers under different conditions of pressure and temperature

    International Nuclear Information System (INIS)

    Dielectric relaxation times over a broad range of temperature and pressure for the glass former phenolphthalein-dimethylether (PDE) reveal a change of dynamics at a characteristic relaxation time τB. The value of τB was found to be largely insensitive to the particular combination of pressure and temperature of the measurement. Data for a second glass former, cresol-phthalein-dimethylether, having a molecular structure very close to that of PDE, were also analysed. In this case, τB is much smaller, so the change of dynamics could not be observed in the elevated pressure experiments. The PDE data were in good agreement with the Adam-Gibbs model near Tg (τ > τB), while deviating for τ B. Finally, a possible connection between the observed TB and theoretical models is presented

  12. High-Temperature Phase Transitions in CsH2PO4 Under Ambient and High-Pressure Conditions: A Synchrotron X-ray Diffraction Study

    Energy Technology Data Exchange (ETDEWEB)

    Botez,C.; Hermosillo, J.; Zhang, J.; Qian, J.; Zhao, Y.; Majzlan, J.; Chianelli, R.; Pantea, C.

    2007-01-01

    To clarify the microscopic origin of the temperature-induced three-order-of-magnitude jump in the proton conductivity of CsH2PO4 (superprotonic behavior), we have investigated its crystal structure modifications within the 25-300 C temperature range under both ambient- and high-pressure conditions using synchrotron x-ray diffraction. Our high-pressure data show no indication of the thermal decomposition/polymerization at the crystal surface recently proposed as the origin of the enhanced proton conductivity. Instead, we found direct evidence that the superprotonic behavior of the title material is associated with a polymorphic structural transition to a high-temperature cubic phase. Our results are in excellent agreement with previous high-pressure ac impedance measurements.

  13. Effects of the nozzle design on the properties of plasma jet and formation of YSZ coatings under low pressure conditions

    Science.gov (United States)

    Sun, Chengqi; Gao, Yang; Yang, Deming; Fu, Yingqing

    2016-06-01

    How to control the quality of the coatings has become a major problem during the plasma spraying. Because nozzle contour has a great influence on the characteristic of the plasma jet, two kinds of plasma torches equipped with a standard cylindrical nozzle and a converging-diverging nozzle are designed for low pressure plasma spraying(LPPS) and very low pressure plasma spraying(VLPPS). Yttria stabilized zirconia(YSZ) coatings are obtained in the reducing pressure environment. The properties of the plasma jet without or with powder injection are analyzed by optical emission spectroscopy, and the electron temperature is calculated based on the ratio of the relative intensity of two Ar I spectral lines. The results show that some of the YSZ powder can be vaporized in the low pressure enlarged plasma jet, and the long anode nozzle may improve the characteristics of the plasma jet. The coatings deposited by LPPS are mainly composed of the equiaxed grains and while the unmelted powder particles and large scalar pores appear in the coatings made by VLPPS. The long anode nozzle could improve the melting of the powders and deposition efficiency, and enhance the coatings' hardness. At the same time, the long anode nozzle could lead to a decrease in the overspray phenomenon. Through the comparison of the two different size's nozzle, the long anode is much more suitable for making the YSZ coatings.

  14. An experimental study on the spray characteristics of residential sprinklers under low-flow and low-pressure conditions

    NARCIS (Netherlands)

    Zlatanovic, L.; Vreeburg, J.H.G.; Hoek, van der J.P.; Poznakovs, I.

    2014-01-01

    An experimental investigation to explore the characteristics of the initial drop screen which was formed by sprinkler heads at low water pressures was carried out. Two commercially available sprinkler heads (with thin and massive frame arms) were modified, not only in terms of deflector plate design

  15. Heat transfer and pressure drop of a gasket-sealed plate heat exchanger depending on operating conditions across hot and cold sides

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Joon [Kookmin University, Seoul (Korea, Republic of); Kim, Hyouck Ju [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2016-05-15

    In a gas engine based cogeneration system, heat may be recovered from two parts: Jacket water and exhaust gas. The heat from the jacket water is often recovered using a plate-type heat exchanger, and is used for room heating and/or hot water supply applications. Depending on the operating conditions of an engine and heat recovery system, there may be an imbalance in the flow rate and supply pressure between the engine side and the heat-recovery side of the heat exchanger. This imbalance causes deformation of the plate, which affects heat transfer and pressure drop characteristics. In the present study, the heat transfer and pressure drop inside a heat exchanger were investigated under varying hot-side and cold-side operating conditions. Thermal efficiency of the plate heat exchanger decreases up to 30% with an operating engine load of 50%. A correction factor for the pressure drop correlation is proposed to account for the deformation caused by an imbalance between the two sides of a heat exchanger.

  16. Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

    Science.gov (United States)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35°C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m2). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  17. 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

    OpenAIRE

    H. Marengo–Mogollón; F.J. Ochoa–Álvarez; C. Cortés–Cortés

    2009-01-01

    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 opt...

  18. 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.

  19. Equation of state in the generalized density scaling regime studied from ambient to ultra-high pressure conditions.

    Science.gov (United States)

    Grzybowski, A; Koperwas, K; Paluch, M

    2014-01-28

    In this paper, based on the effective intermolecular potential with well separated density and configuration contributions and the definition of the isothermal bulk modulus, we derive two similar equations of state dedicated to describe volumetric data of supercooled liquids studied in the extremely wide pressure range related to the density range, which is extremely wide in comparison with the experimental range reached so far in pressure-volume-temperature measurements of glass-forming liquids. Both the equations comply with the generalized density scaling law of molecular dynamics versus h(ρ)/T at different densities ρ and temperatures T, where the scaling exponent can be in general only a density function γ(ρ) = d ln h/d ln ρ as recently argued by the theory of isomorphs. We successfully verify these equations of state by using data obtained from molecular dynamics simulations of the Kob-Andersen binary Lennard-Jones liquid. As a very important result, we find that the one-parameter density function h(ρ) analytically formulated in the case of this prototypical model of supercooled liquid, which implies the one-parameter density function γ(ρ), is able to scale the structural relaxation times with the value of this function parameter determined by fitting the volumetric simulation data to the equations of state. We also show that these equations of state properly describe the pressure dependences of the isothermal bulk modulus and the configurational isothermal bulk modulus in the extremely wide pressure range investigated by the computer simulations. Moreover, we discuss the possible forms of the density functions h(ρ) and γ(ρ) for real glass formers, which are suggested to be different from those valid for the model of supercooled liquid based on the Lennard-Jones intermolecular potential. PMID:25669550

  20. Atomistic and Ab initio modeling of CaAl2O4 high-pressure polymorphs under Earth's mantle conditions

    Science.gov (United States)

    Eremin, N. N.; Grechanovsky, A. E.; Marchenko, E. I.

    2016-05-01

    Semi-empirical and ab initio theoretical investigation of crystal structure geometry, interatomic distances, phase densities and elastic properties for some CaAl2O4 phases under pressures up to 200 GPa was performed. Two independent simulation methods predicted the appearance of a still unknown super-dense CaAl2O4 modification. In this structure, the Al coordination polyhedron might be described as distorted one with seven vertices. Ca atoms were situated inside polyhedra with ten vertices and Ca-O distances from 1.96 to 2.49 Å. It became the densest modification under pressures of 170 GPa (density functional theory prediction) or 150 GPa (semi-empirical prediction). Both approaches indicated that this super-dense CaAl2O4 modification with a "stuffed α-PbO2" type structure could be a probable candidate for mutual accumulation of Ca and Al in the lower mantle. The existence of this phase can be verified experimentally using high pressure techniques.

  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. Pore Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir Pressure-Temperature Conditions Using Small-Angle Neutron Scattering

    Science.gov (United States)

    Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.

    2015-12-01

    Oil/gas produced from unconventional reservoirs has become strategically important for the US domestic energy independence. In unconventional realm, hydrocarbons are generated and stored in nanopores media ranging from a few to hundreds of nanometers. Fundamental knowledge of coupled thermo-hydro-mechanical-chemical (THMC) processes that control fluid flow and propagation within nano-pore confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer pores creates many complex rock-fluid interface interactions. It is imperative to promote innovative experimental studies to decipher physical and chemical processes at the nanopore scale that govern hydrocarbon generation and mass transport of hydrocarbon mixtures in tight shale and other low permeability formations at reservoir pressure-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between pore characteristics of the Wolfcamp shale from Western Texas and the shale interaction with fluids at reservoir P-T conditions using small-angle neutron scattering (SANS). We have performed SANS measurements of the shale rock in single fluid (e.g., H2O and D2O) and multifluid (CH4/(30% H2O+70% D2O)) systems at various pressures up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different pressures with H2O as the pressure medium. Our data analysis using IRENA software suggests that the principal changes of pore volume in the shale occurred on smaller than 50 nm pores and pressure at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into pores; with decreasing P, water is retained in the pores.

  3. 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 only in species 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

  4. The major influence of the atmosphere on intracranial pressure: an observational study

    Science.gov (United States)

    Herbowski, Leszek

    2016-06-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p < 0.05) and all the measurements are perfectly reliable (Bland-Altman coefficient is 4.8 %). It appears from this study that changes in absolute intracranial pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  5. The major influence of the atmosphere on intracranial pressure: an observational study

    Science.gov (United States)

    Herbowski, Leszek

    2016-06-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p Altman coefficient is 4.8 %). It appears from this study that changes in absolute intracranial pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  6. 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)

  7. 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

  8. Seafloor slow vertical displacement inferred by sea bottom pressure measurements in shallow water: an application to the Campi Flegrei volcanic area

    Science.gov (United States)

    Chierici, Francesco; Pignagnoli, Luca; Iannaccone, Giovanni; Guardato, Sergio; Locritani, Marina; Embriaco, Davide; Donnarumma, Gian Paolo; La Rocca, Adriano; Pinto, Salvatore; Beranzoli, Laura

    2016-04-01

    The vertical component of sea floor displacement in tectonic or volcanically active areas can be observed using sea bottom pressure recorders. These measurements are usually acquired in areas affected by strong dynamics with large vertical displacement and in deep water, where the noise induced by the sea state is low. Under these conditions the contribution of the variation of sea water density and the contribution of the instrumental drift - a typical feature of the bottom pressure recorders - can be negligible. We have developed a new methodology to monitor vertical sea floor displacement both in areas with small and slow deformation, and in shallow water. We take advantage of bottom pressure recorder data, augmented with ancillary sea level, barometric and water physical parameters measurements. We have applied this method to the data collected by a bottom pressure recorder deployed at 100 m w.d. in the Campi Flegrei Caldera as part of CUMAS multiparameter monitoring system. During several months of 2011 we have observed a small uplift episode related to the bradiseismic activity of the area. These observations are compatible with other geodetic data recorded in the region and provide unprecedented measurements of the vertical deformation in the marine area.

  9. 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.

  10. Effect of torsion conditions under high pressure on the structure and strengthening of the Zr-1% Nb alloy

    Science.gov (United States)

    Rogachev, S. O.; Rozhnov, A. B.; Nikulin, S. A.; Rybal'chenko, O. V.; Gorshenkov, M. V.; Chzhen, V. G.; Dobatkin, S. V.

    2016-04-01

    The effect of temperature and degree of deformation upon severe plastic deformation by torsion under a high pressure on the structure, phase composition, and microhardness of the industrial zirconium Zr-1% Nb alloy (E110) has been studied. The high-pressure torsion (HPT) (with N = 10 revolutions) of the Zr-1% Nb alloy at room temperature results in the formation of grain-subgrain nanosize structure with an average size of structural elements of 65 nm, increase in the microhardness by 2.3-2.8 times (to 358 MPa), and α-Zr → β-Zr and α-Zr → ω-Zr phase transformations. The increase in the HPT temperature to 200°C does not lead to a decrease in the microhardness of alloy owing to the increase in the fraction of ω-Zr phase, though the average size of structural elements increases to 125 nm. The increase in the temperature to 400°C during HPT with N = 10 revolutions leads to the grain growth in the α-Zr grain structure (~90%) to 160 nm and a decrease in the microhardness to 253-276 HV.

  11. 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)

  12. Tolerance testing of passive radio frequency identification tags for solvent, temperature, and pressure conditions encountered in an anatomic pathology or biorepository setting

    Directory of Open Access Journals (Sweden)

    Alina A Leung

    2010-01-01

    Full Text Available Background: Radio frequency identification (RFID tags have potential for use in identifying and tracking biospecimens in anatomic pathology and biorepository laboratories. However, there is little to no data on the tolerance of tags to solutions, solvents, temperatures, and pressures likely to be encountered in the laboratory. The functioning of the Hitachi Mu-chip RFID tag, a candidate for pathology use, was evaluated under such conditions. Methods: The RFID tags were affixed to cryovials containing tissue or media, glass slides, and tissue cassettes. The tags were interrogated for readability before and after each testing condition or cycle. Individual tags were subjected to only one testing condition but for multiple cycles. Testing conditions were: 1 Ten wet autoclave cycles (121˚C, 15 psi; 2 Ten dry autoclave cycles (121˚C, 26 psi; 3 Ten tissue processor cycles; 4 Ten hematoxylin and eosin (H&E staining cycles; 5 Ten antigen retrieval pressure cooker cycles (125˚C, 15 psi; 6 75 o C for seven days; 7 75-59 o C day/night cycles for 7 days; 8 -80 o C, -150 o C, or -196 o C for 12 months; 9 Fifty freeze-thaw cycles (-196 o C to 22 o C. Results: One hundred percent of tags exposed to cold temperatures from -80 to -196 o C (80 tags, 1120 successful reads, high temperatures from 52 to 75 o C (40 tags, 420 reads, H & E staining (20 tags, 200 reads, pressure cooker antigen retrieval (20 tags, 200 reads, and wet autoclaving (20 tags, 200 reads functioned well throughout and after testing. Of note, all 20 tested tags tolerated 50 freeze-thaw cycles and all 60 tags subjected to sustained freezing temperatures were readable after 1 year. One dry autoclaved tag survived nine cycles but failed after the tenth. The remaining 19 tags were readable after all 10 dry autoclave cycles. One tag failed after the first tissue processing cycle while the remaining 19 tags survived all 10 tissue processing cycles. Conclusions: In this preliminary study, these RFID

  13. Parametric study on effect of break size during LOCA on thermal hydraulic conditions in an indian pressurized heavy water reactor (220 MWe)

    Energy Technology Data Exchange (ETDEWEB)

    Rao, G.S.; Gupta, S.K.; Raj, V.V. [Bhabha Atomic Research Centre, Mumbai (India)

    1999-07-01

    Loss Of Coolant Accident (LOCA) in a Pressurized Heavy Water Reactor (PHWR) leads to coolant expulsion in a primary heat transport system resulting in depressurization and possible core voiding. This results in deterioration of cooling conditions in reactor channels and increase in power before reactor shutdown, leading to higher fuel temperatures. Coolant expulsion rates during LOCA are dictated by critical flow conditions governed by initial plant conditions prior to the accident, break geometry, location of break, etc. In addition the PHWRs have positive void-coefficient of reactivity for coolant resulting in reactor power rise in earlier part of LOCA, when the stored heat of the fuel has yet not been removed. If, in addition, heat transfer to the coolant drops sharply very high fuel surface temperatures are expected. The paper describes analyses carried out for three different break sizes. (author)

  14. A non-local Richards equation to model infiltration into highly heterogeneous media under macroscopic non-equilibrium pressure conditions

    Science.gov (United States)

    Neuweiler, I.; Dentz, M.; Erdal, D.

    2012-04-01

    Infiltration into dry strongly heterogeneous media, such as fractured rocks, can often not be modelled by a standard Richards equation with homogeneous parameters, as the averaged water content is not in equilibrium with the averaged pressure. Often, double continua approaches are used for such cases. We describe infiltration into strongly heterogeneous media by a Richards model for the mobile domain, that is characterized by a memory kernel that encodes the local mass transfer dynamics as well as the geometry of the immobile zone. This approach is based on the assumption that capillary flow can be approximated as diffusion. We demonstrate that this approximation is in many cases justified. Comparison of the model predictions to the results of numerical simulations of infiltration into vertically layered media shows that the non-local approach describes well non-equilibrium effects due to mass transfer between high and low conductivity zones.

  15. Raman analysis of epitaxial graphene grown on 4H-SiC (0001) substrate under low pressure condition

    Institute of Scientific and Technical Information of China (English)

    Wang Dang-Chao; Zhang Yu-Ming; Zhang Yi-Men; Lei Tian-Min; Guo Hui; Wang Yue-Hu; Tang Xiao-Yan; Wang Hang

    2011-01-01

    In this paper,we report a feasible route of growing epitaxial graphene on 4H-SiC (0001) substrate in a low pressure of 4 mbar (1 bar=105 Pa) with an argon flux of 2 standard liters per minute at 1200,1300,1400,and 1500 ℃ in a commercial chemical vapour deposition SiC reactor.Using Raman spectroscopy and scanning electron microscopy,we confirm that epitaxial graphene evidently forms on SiC surface above 1300 ℃ with a size of several microns.By fitting the 2D band of Raman data with two-Lorentzian function,and comparing with the published reports,we conclude that epitaxial graphene grown at 1300 ℃ is four-layer graphene.

  16. Extreme Air Pollution Conditions Adversely Affect Blood Pressure and Insulin Resistance: The Air Pollution and Cardiometabolic Disease Study.

    Science.gov (United States)

    Brook, Robert D; Sun, Zhichao; Brook, Jeffrey R; Zhao, Xiaoyi; Ruan, Yanping; Yan, Jianhua; Mukherjee, Bhramar; Rao, Xiaoquan; Duan, Fengkui; Sun, Lixian; Liang, Ruijuan; Lian, Hui; Zhang, Shuyang; Fang, Quan; Gu, Dongfeng; Sun, Qinghua; Fan, Zhongjie; Rajagopalan, Sanjay

    2016-01-01

    Mounting evidence supports that fine particulate matter adversely affects cardiometabolic diseases particularly in susceptible individuals; however, health effects induced by the extreme concentrations within megacities in Asia are not well described. We enrolled 65 nonsmoking adults with metabolic syndrome and insulin resistance in the Beijing metropolitan area into a panel study of 4 repeated visits across 4 seasons since 2012. Daily ambient fine particulate matter and personal black carbon levels ranged from 9.0 to 552.5 µg/m(3) and 0.2 to 24.5 µg/m(3), respectively, with extreme levels observed during January 2013. Cumulative fine particulate matter exposure windows across the prior 1 to 7 days were significantly associated with systolic blood pressure elevations ranging from 2.0 (95% confidence interval, 0.3-3.7) to 2.7 (0.6-4.8) mm Hg per SD increase (67.2 µg/m(3)), whereas cumulative black carbon exposure during the previous 2 to 5 days were significantly associated with ranges in elevations in diastolic blood pressure from 1.3 (0.0-2.5) to 1.7 (0.3-3.2) mm Hg per SD increase (3.6 µg/m(3)). Both black carbon and fine particulate matter were significantly associated with worsening insulin resistance (0.18 [0.01-0.36] and 0.22 [0.04-0.39] unit increase per SD increase of personal-level black carbon and 0.18 [0.02-0.34] and 0.22 [0.08-0.36] unit increase per SD increase of ambient fine particulate matter on lag days 4 and 5). These results provide important global public health warnings that air pollution may pose a risk to cardiometabolic health even at the extremely high concentrations faced by billions of people in the developing world today.

  17. Influence of pressure conditions and back-filling materials on the durability of bore-hole ground loops; Lebensdauer von Erdwaermesonden in Bezug auf Druckverhaeltnisse und Hinterfuellung

    Energy Technology Data Exchange (ETDEWEB)

    Rohner, R. [E. Rohner, Arnegg (Switzerland); Rybach, L.; Salton, M. [Swiss Federal Institute of Technology (ETHZ), Institut fuer Geophysik, Zuerich (Switzerland)

    2001-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) discusses the influence of the relatively high pressures found in ground loops at depths of more than 200 metres and the effects caused by overloading the ground loops. The latter can cause the back-filling between the ground loop and the surrounding rock to freeze. The report describes tests carried out on 70-metre and 265-metre deep test bore-hole installations. The results of investigations into the influence of such pressure conditions on the materials of the ground loop and their service life are presented. The results are also compared with simulations using the FRACTure and EED calculation programmes. Details are given on the bore-holes with respect to their geology and construction. The report concludes that bore-hole ground loops can be considered as being very robust components with a long service life, provided they are designed and installed according to accepted professional standards.

  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. Simulation of flow excursion and thermal siphon under natural circulation condition with lower pressure and lower quality

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The simulation of flow excursion was conducted under HRTL-5 condition.The mechanism analysis and the simulation of thermal siphon process were also performed.The result shows that the computer code can be used to simulate the static instability of a natural circulation system and the simulation of flow excursion almost conforms to the experiment result.

  20. A predictive model for the influence of food components on survival of Listeria monocytogenes LM 54004 under high hydrostatic pressure and mild heat conditions.

    Science.gov (United States)

    Gao, Yu-Long; Ju, Xing-Rong; Wu-Ding

    2007-07-15

    The combination of high hydrostatic pressure with mild temperature was explored to achieve a predictive model of microbial inactivation in food matrix processing. The pressure processing conditions were fixed at 448 MPa for 11 min at the treatment temperature of 41 degrees C, which have been determined as the optimum processing conditions considering six log-cycle reductions of Listeria monocytogenes. Based on the results, response surface methodology (RSM) was performed in the present work, the influence of food components like soybean protein (0-5.00%), sucrose (0.25-13.25%), bean oil (0-10.00%), and pH (4-10) of the food matrix on survival of L. monocytogenes by high pressure and mild heat was studied, and a quadratic predictive model for the influence of food components and pH of food matrix on L. monocytogenes reduction by high pressure and mild heat was built with RSM accurately. The experimental results showed that the efficiency of L. monocytogenes reduction in milk buffer and food matrix designed in the present work, under the HPP treatment process parameters described above, were different. The soybean protein (P=0.0086), sucrose (P<0.0001), and pH (P=0.0136) significantly affected reduction of L. monocytogenes, but the effect of bean oil on reduction of L. monocytogenes was not significant (P=0.1028). The predictive model is significant since the level of significance was P<0.0001 and the calculated F value (11.53) is much greater than the tabulated F value (F(0.01 (14, 5))=9.77). Moreover, the adequacy of the predictive model equation for predicting the level of L. monocytogenes reduction was verified effectively by the validation data.

  1. Asymmetric Hollow Fiber Membranes for Separation of CO 2 from Hydrocarbons and Fluorocarbons at High-Pressure Conditions Relevant to C 2 F 4 Polymerization

    KAUST Repository

    Kosuri, Madhava R.

    2009-12-02

    Separation of high-pressure carbon dioxide from fluorocarbons is important for the production of fluoropolymers such as poly(tetrafluoroethylene). Typical polymeric membranes plasticize under high CO2 partial pressure conditions and fail to provide adequate selective separations. Torlon, a polyamide-imide polymer, with the ability to form interchain hydrogen bonding, is shown to provide stability against aggressive CO2 plasticization. Torlon membranes in the form of asymmetric hollow fibers (the most productive form of membranes) are considered for an intended separation of CO 2/C2F4. To avoid safety issues with tetrafluoroethylene (C2F4), which could detonate under testing conditions, safer surrogate mixtures (C2H2F 2 and C2H4) are considered in this paper. Permeation measurements (at 35 °C) indicate that the Torlon membranes are not plasticized even up to 1250 psi of CO2. The membranes provide mixed gas CO2/C2H2F2 and CO 2/C2H4 selectivities of 100 and 30, respectively, at 1250 psi partial pressures of CO2. On the basis of the measured separation performances of CO2/C2H 2F2 and CO2/C2H4 mixtures, the selectivity of the CO2/C2F4 mixture is expected to be greater than 100. Long-term stability studies indicate that the membranes provide stable separations over a period of 5 days at 1250 psi partial pressures of CO2, thereby making the membrane approach attractive. © 2009 American Chemical Society.

  2. 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.

  3. Effects of operating conditions on molten-salt electrorefining for zirconium recovery from irradiated Zircaloy-4 cladding of pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jaeyeong, E-mail: d486916@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Choi, Sungyeol [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Sohn, Sungjune [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Kim, Kwang-Rag [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Hwang, Il Soon [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2014-08-15

    Highlights: • Computational simulation on electrorefining of irradiated Zircaloy-4 cladding. • Composition of irradiated Zircaloy-4 cladding of pressurized water reactor. • Redox behavior of elements in irradiated Zircaloy cladding during electrorefining. • Effect of electrorefining operating conditions on decontamination factor. - Abstract: To reduce the final waste volume from used nuclear fuel assembly, it is significant to decontaminate irradiated cladding. Electrorefining in high temperature molten salt could be one of volume decontamination processes for the cladding. This study examines the effect of operating conditions on decontamination factor in electrorefining of irradiated Zircaloy-4 cladding of pressurized water reactor. One-dimensional time-dependent electrochemical reaction code, REFIN, was utilized for simulating irradiated cladding electrorefining. Composition of irradiated Zircaloy was estimated based on ORIGEN-2 and other literatures. Co and U were considered in electrorefining simulation with major elements of Zircaloy-4 to represent activation products and actinides penetrating into the cladding respectively. Total 240 cases of electrorefining are simulated including 8 diffusion boundary layer thicknesses, 10 concentrations of contaminated molten salt and 3 termination conditions. Decontamination factors for each case were evaluated and it is revealed that the radioactivity of Co-60 in recovered zirconium on cathode could decrease below the clearance level when initial concentration of chlorides except ZrCl{sub 4} is lower than 1 × 10{sup −11} weight fraction if electrorefining is finished before anode potential reaches −1.8 V (vs. Cl{sub 2}/Cl{sup −})

  4. Development of surface tension measurement method of high temperature melts in consideration of oxygen partial pressure under microgravity condition

    OpenAIRE

    Ozawa, Shunpei; Watanabe, Masahito; Morohoshi, Keisuke; Aoyagi, Tomowo; Takenaga, Noriaki; Adachi, Masayoshi; Mizuno, Akitoshi; Hibiya, Taketoshi; Fujii, Hideki; 小澤, 俊平; 渡邉, 匡人; 諸星, 圭祐; 青柳, 智勇; 尺長, 憲昭; 安達, 正芳

    2009-01-01

    The electromagnetic levitator for microgravity condition called PFLEX (Parabolic Flight Levitation Experiment Facility) was improved for precision measurement of surface tension of high temperature melt. We succeeded in the electromagnetic levitation of molten copper during the parabolic flight regardless of the gravitational change from 1.5 G to micro G. Several peaks were observed in the frequency spectrum for the surface oscillation of the molten copper, the spectrum becomes simple under m...

  5. Laboratory measurements of the microwave opacity and vapor pressure of sulfuric acid vapor under simulated conditions for the middle atmosphere of Venus

    Science.gov (United States)

    Steffes, P. G.

    1985-01-01

    Microwave absorption measurements at wavelengths of 13.4 and 3.6 cm were made in gaseous H2SO4 in a CO2 atmosphere under simulated conditions for the Venus middle atmosphere. The results suggest that abundances of gaseous H2SO4 on the order of 15-30 ppm could account for the absorption observed by radio occultation measurements at these wavelengths. They also imply that such abundances would correspond to saturation vapor pressure existing at or above the 46-48-km range, which correlates with the observed cloud base.

  6. 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)

  7. 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.

  8. 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)

  9. Asthma and climatic conditions: experience from Bermuda, an isolated island community.

    OpenAIRE

    Carey, M. J.; Cordon, I

    1986-01-01

    A retrospective study of patients attending the emergency department with acute asthma was performed in Bermuda. Climatic data (barometric pressure, rainfall, humidity, and wind strength and direction) were obtained and compared with frequency of exacerbations of asthma. Three factors--namely, relative humidity, average daily temperature, and northeasterly winds--were found to be related to worsening asthma. Owing to Bermuda's lack of pollution and aeroallergens it was thought that these weat...

  10. Heat pump control method based on direct measurement of evaporation pressure to improve energy efficiency and indoor air temperature stability at a low cooling load condition

    International Nuclear Information System (INIS)

    Highlights: • New heat pump control method was developed. • Experimental investigation on performance of heat pump with various control method. • New control method appeared to improve the stability of indoor air temperature. • New control method appeared to have a potential to reduce power consumption. - Abstract: The control systems of conventional heat pumps have an input of refrigerant temperature at the evaporator outlet to maintain superheat at proper level. In order to develop a control method that can be used to achieve better indoor thermal comfort and energy efficiency at a low cooling load condition than the current control method, a new method of the evaporation pressure control based on the evaporator outlet pressure reading (EPCP) was developed. The changes in the stability of indoor air temperature and power consumption were measured while changing the compressor frequency in accordance with the new control method. Compared with the evaporation pressure control based on the evaporator outlet temperature reading, the EPCP control method appeared to improve the stability of room air temperature or occupant thermal comfort significantly

  11. Large eddy simulation of pressure fluctuations at off-design condition in a Francis turbine based on cavitation model

    Science.gov (United States)

    Su, W. T.; Li, X. B.; Li, F. C.; Han, W. F.; Wei, X. Z.; Guo, J.

    2013-12-01

    To study the instability of a Francis turbine at off-design operating condition, a hydraulic model was established and the flow characteristics at the off-design point were studied based on large eddy simulation (LES). The simulation was conducted for both single phase model and cavitation model. The results were compared with the experimental data. Results show that the simulation based on cavitation model can capture more channel vortex structures than single phase calculation. The result of vortex rope by cavitation model is similar to the experimental result. The dominant frequency can be obtained by these two methods, while the result based on cavitation model can capture the high frequency component at the inlet of draft tube. Great difference can be seen from the internal flow of the two simulation results. These conclusions can provide a basis for the study of instability of Francis turbine.

  12. Unsteady measurement of the static pressure on the impeller blade surfaces and optical observation on centrifugal pumps under varying liquid/gas two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Suryawijaya, P.; Kosyna, G. [Pfleiderer-Inst. fuer Stroemungsmaschinen, Technische Univ. Braunschweig, Braunschweig (Germany)

    2003-03-01

    A liquid/gas two-phase flow (liquid contains undissolved gas) can be found in a wide range of pump applications, especially in chemical industries, off-shore oil production and nuclear reactors. It is well known that the performance of single stage centrifugal pumps decreases rapidly under liquid/gas two-phase flow conditions. The consequences of entrained gas depend on the relative amount of gas and liquid present, and vary from a slight deterioration on performance up to complete blockage known as ''gas locking''. Before gas locking occurs, other phenomena such as pump head degradation, surging and ''gas blocking'' take place. For two-phase flow applications of centrifugal pump the influence of the entrained gas on pump behaviour must be predictable. This is a hard task due to the complexity involved in modelling multiphase flow inside turbomachines. An accurate prediction of the performance for any pump handling liquid/gas mixture is still a problem today. This paper reports on a research project, carried out at the Pfleiderer-Institute for Turbomachinery, Technical University of Braunschweig, Germany. The purpose of this project is to get a better understanding of the physical background of the two-phase flow behaviour of the centrifugal pumps by measuring the static pressure on the impeller blade surfaces and by optical observation under varying two-phase flow conditions. The results will also be used to validate a numerical code, which is developed in a related research project. The project is focused on two centrifugal pumps, one scaled down from the other, having the same low specific speed number ns = 27. The pumps are operating under variable two-phase flow conditions. Air and water were used as working fluids. Flow structures within the pump impeller and the overall pump performance are investigated by numerical simulation and experiments. One impeller blade of the pump is equipped with eight KULITE trademark sub

  13. Ultrasonic P and S wave Velocity Measurements at Mid-to-Lower Crustal Conditions of Pressure and Temperature in a Piston Cylinder Apparatus

    Science.gov (United States)

    Ishikawa, M.; Arima, M.

    2007-12-01

    In order to interpret seismic structures in terms of rock type, temperature anomaly, degree of partial melting and distribution of fluids, we have carried out research on the elastic properties of the crustal rocks using ultrasonic measurements. We have developed techniques to perform ultrasonic velocity measurements at mid-to-lower crustal conditions of pressure and temperature. These techniques are now been applied to study the rock physics of exposed deep crustal sections and crustal xenoliths, including gabbro, tonalite, granite, anorthosite, granulite and amphibolite, which were collected from the Tanzawa Mountain of central Japan, Kohistan area of Pakistan, Ichinomegata of NE Japan, Takashima and Kurose of SW Japan, and granulite-facies complex of East Antarctica. Compressional (P) and shear (S) wave velocities for these rock specimens are measured in piston cylinder apparatus. In order to compare directly to seismic velocities at the deep island arc pressures and temperatures, we developed ultrasonic velocity measurements using buffer rod technique. Pt buffer rod is used to isolate the piezoelectric transducer from the high-temperature condition. Travel times through the rock sample were determined with the pulse reflection technique. We are developing a method for simultaneous P-wave and S-wave velocity measurements using dual-mode piezoelectric transducer which generates P-waves and S-waves simultaneously. Using these techniques, we can determine Vp/Vs ratio and Poisson's ratio precisely.

  14. 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)

  15. Photovoltaic barometer; Barometre photovoltaique

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2009-04-15

    spain and Germany set the pace for the world photovoltaic market in 2008, which grew to more than twice its 2007 size. The European Union continued to drive photocell installation with an additional 4 592.3 MWp in 2008, or 151.6% growth over 2007. However, European growth prospects for the photovoltaic market in 2009 are being dampened by the global financial crisis and the scheduled slow-down of the Spanish market. (author)

  16. Photovoltaic barometer; Barometre photovoltaique

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-04-15

    The photovoltaic sector is continuing on track, just as the extent of solar energy's electricity-generating potential is dawning on the public mind. The annual global installation figure was up more than twofold in 2010 (rising from just short of 7000 MWp in 2009). It leapt to over 16000 MWp, bringing worldwide installed photovoltaic capacity close to 38000 MWp. The photovoltaic power generated in the European Union at the end of 2010 reached 22.5 TWh which means an additional capacity of 13023 MWp during 2010. Concerning the cumulated installed capacity, Germany and Spain rank first and second in the European Union with respectively 17370 MWp and 3808 MWp

  17. A priori and a posteriori investigations for developing large eddy simulations of multi-species turbulent mixing under high-pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Borghesi, Giulio [California Institute of Technology, Pasadena, California 91125 (United States); Bellan, Josette, E-mail: josette.bellan@jpl.nasa.gov [California Institute of Technology, Pasadena, California 91125 (United States); Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099 (United States)

    2015-03-15

    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

  18. 城市化对城市及周围附近气压变化影响分析%THE URBANIZATION INFLUENCES THE BAROMETRIC CHANGE OF THE CITY AND SURROUNDINGS

    Institute of Scientific and Technical Information of China (English)

    陈德英; 梁国坚; 田小琪

    2011-01-01

    By comparatively analyzing the barometric data of the city centre which is revised to the sea level and the suburb, we found that while the barometric around the sea level of the two places changes in the same trend, the two places' barometric data exist significant differences. As the changes of barometric field which closes to the city and nearby caused by urban environment impact, the barometric in city center is lower than the barometric in suburb. Passing by more detection, the variety regulations which draws from the absolute value of the difference between city center and suburb sea - level barometric and can be describe as: for the season-“ winter maximum, the spring and autumn time less and summer minimum” ;for one day-“ not obvious in the daytime and obvious in the nighttime” forms “the city barometric marsh land effect”, that effect is another important reason which resulted in the barometric difference in the two sides except the differences of the height above the sea level.At present, domestic and foreign workers in this area seldom carried out research about “The influences caused by the urbanization on the barometric changes of the city and surroundings”. This experiment which has also studied the correlation between “the city barometric marsh land effect” and “the city heat island effect” is a beneficial attempt for the further research so that to reveal the law of “the influences of the urbanization on the urban climate”.%通过对订正到海平面高度的城市市中心与市郊两地气压的对比分析,发现虽然市中心与市郊两地海平面气压变化趋势一致,但两地气压数据存在显著差异,由于城市环境影响形成了城市及周围附近气压场的变化,市中心比市郊气压要低,经过比较发现,市中心与市郊海平面气压差绝对值存在着"冬季大、春秋次之、夏季最小"的季节变化规律,以及"白天不明显、夜间显著"日变化规律的"城市气

  19. Comparison of Surfactant Distributions in Pressure-Sensitive Adhesive Films Dried from Dispersion under Lab-Scale and Industrial Drying Conditions.

    Science.gov (United States)

    Baesch, S; Siebel, D; Schmidt-Hansberg, B; Eichholz, C; Gerst, M; Scharfer, P; Schabel, W

    2016-03-01

    Film-forming latex dispersions are an important class of material systems for a variety of applications, for example, pressure-sensitive adhesives, which are used for the manufacturing of adhesive tapes and labels. The mechanisms occurring during drying have been under intense investigations in a number of literature works. Of special interest is the distribution of surfactants during the film formation. However, most of the studies are performed at experimental conditions very different from those usually encountered in industrial processes. This leaves the impact of the drying conditions and the resulting influence on the film properties unclear. In this work, two different 2-ethylhexyl-acrylate (EHA)-based adhesives with varying characteristics regarding glass transition temperature, surfactants, and particle size distribution were investigated on two different substrates. The drying conditions, defined by film temperature and mass transfer in the gas phase, were varied to emulate typical conditions encountered in the laboratory and industrial processes. Extreme conditions equivalent to air temperatures up to 250 °C in a belt dryer and drying rates of 12 g/(m(2)·s) were realized. The surfactant distributions were measured by means of 3D confocal Raman spectroscopy in the dry film. The surfactant distributions were found to differ significantly with drying conditions at moderate film temperatures. At elevated film temperatures the surfactant distributions are independent of the investigated gas side transport coefficients: the heat and mass transfer coefficient. Coating on substrates with significantly different surface energies has a large impact on surfactant concentration gradients, as the equilibrium between surface and bulk concentration changes. Dispersions with higher colloidal stability showed more homogeneous lateral surfactant distributions. These results indicate that the choice of the drying conditions, colloidal stability, and substrates is crucial

  20. 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.

  1. Radionuclides release from re-irradiated fuel under high temperature and pressure conditions. Gamma-ray measurements of VEGA-5 test

    Energy Technology Data Exchange (ETDEWEB)

    Hidaka, Akihide; Kudo, Tamotsu; Nakamura, Takehiko; Kanazawa, Toru; Kiuchi, Toshio; Uetsuka, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The VEGA (Verification Experiments of radionuclides Gas/Aerosol release) program is being performed at JAERI to clarify mechanisms of radionuclides release from irradiated fuel during severe accidents and to improve source term predictability. The fifth VEGA-5 test was conducted in January 2002 to confirm the reproducibility of decrease in cesium release under elevated pressure that was observed in the VEGA-2 test and to investigate the release behavior of short-life radionuclides. The PWR fuel of 47 GWd/tU after about 8.2 years of cooling was re-irradiated at Nuclear Safety Research Reactor (NSRR) for 8 hours before the heat-up test. After that, the two pellets of 10.9 g without cladding were heated up to about 2,900 K at 1.0 MPa under the inert He condition. The experiment reconfirmed the decrease in cesium release rate under the elevated pressure. The release data on short-life radionuclides such as Ru-103, Ba-140 and Xe-133 that have never been observed in the previous VEGA tests without re-irradiation was obtained using the {gamma} ray measurement. (author)

  2. Defect formation in aqueous environment: Theoretical assessment of boron incorporation in nickel ferrite under conditions of an operating pressurized-water nuclear reactor (PWR)

    Science.gov (United States)

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

    2015-06-01

    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 NiFe2O4 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 the reactor. In this work an innovative approach is used to combine first-principles calculations with thermodynamic data to evaluate the possibility of B incorporation into the crystal structure of NiFe2O4 , under conditions typical to operating nuclear pressurized water nuclear reactors. Analyses of temperature and pH dependence of the defect formation energies indicate that B can accumulate in NiFe2O4 as an interstitial impurity and may therefore be a major contributor to the anomalous axial power shift observed in nuclear reactors. This computational approach is quite general and applicable to a large variety of solids in equilibrium with aqueous solutions.

  3. Intermittent Behavior of the Separated Boundary Layer along the Suction Surface of a Low Pressure Turbine Blade under Periodic Unsteady Flow Conditions

    Science.gov (United States)

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

    2005-01-01

    The paper experimentally and theoretically studies the effects of periodic unsteady wake flow and aerodynamic characteristics on boundary layer development, separation and re-attachment along the suction surface of a low pressure turbine blade. The experiments were carried out at Reynolds number of 110,000 (based on suction surface length and exit velocity). For one steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, intermittency behaviors were experimentally and theoretically investigated. The current investigation attempts to extend the intermittency unsteady boundary layer transition model developed in previously to the LPT cases, where separation occurs on the suction surface at a low Reynolds number. The results of the unsteady boundary layer measurements and the intermittency analysis were presented in the ensemble-averaged and contour plot forms. The analysis of the boundary layer experimental data with the flow separation, confirms the universal character of the relative intermittency function which is described by a Gausssian function.

  4. Influence of discharge production conditions, gas pressure, current intensity and voltage type, on SF6 dissociation under point-plane corona discharges

    Science.gov (United States)

    Belarbi, A.; Pradayrol, C.; Casanovas, J.; Casanovas, A. M.

    1995-02-01

    The study of the formation of Sulfur Hexafluoride (SF6) dissociation products under point to plane corona discharges was carried out at P(sub SF(6)) = 300 kPa using different discharges production conditions (50 Hz ac voltage, dc negative polarity voltage, mean discharge current intensity bar-I varying between 2 and 45 micro-A for dc negative polarity voltage), for two plane electrode materials (aluminum and stainless steel), and moisture levels (200 and 2000 ppm(sub v) H2O). The stable gaseous by-products formed (SO2F2, SOF4, SOF2, and S2F10) were assayed by gas-phase chromatography. The results indicate an important effect of the metal constituting the plane electrode and of the moisture conditions whatever the SF6 pressure (100-300 kPa), discharges intensity (bar-I) and voltage type studied. An effect of the increase of SF6 pressure up to 300 kPa was mainly observed for S2F10 and corresponds to a greater formation of this compound with P(sub SF(6)). The influence of the mean discharge current intensity on SF6 by-product formation carried out for a transported charge of 1 C showed that for I less than or equal to 10 micro-A, the effect varies according to the compound considered and depends on the water content of the SF6 and/or on the plane electrode material, whereas for bar-I greater than 10 micro-A, the levels of the four compound studied hardly vary with the current. Comparison of results obtained under ac and dc voltage for a cumulated charge of between 0.5 and 11 C showed that (SO2F2+SOF4) and SOF2 were formed in larger quantities with ac than with dc, unlike S2F10 for which the opposite effect was observed.

  5. Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kiran Kumar, M., E-mail: mkiran@barc.gov.i [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Gaonkar, Krishna; Ghosh, Swati; Kain, Vivekanand [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bojinov, Martin [Department of Physical Chemistry, University of Chemical Technology and Metallurgy, Kl. Ohridski Blvd. 8, 1756 Sofia (Bulgaria); Saario, Timo [VTT Materials and Building, VTT Technical Research Centre of Finland, P.O. Box 1000, Kemistintie 3, FIN-02044 VTT, Espoo (Finland)

    2010-06-15

    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{sup +} electrolyte at room temperature as a function of potential in a range of -0.8 to +0.3 V{sub SCE}. 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 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

  6. Evaluation of pH control agents influencing on corrosion of carbon steel in secondary water chemistry condition of pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, In Hyoung; Jung, Hyun Jun; Cho, Dae Chul [Dept. of Energy and Environmental Engineering, Soonchunhyang University, Asan (Korea, Republic of)

    2014-06-15

    The effect of various pH agents on the corrosion behavior of carbon steel was investigated under a simulated secondary water chemistry condition of a pressurized water reactor (PWR) in a laboratory, and the steel's corrosion performance was compared with the field data obtained from Uljin NPP unit 2 reactor. All tests were carried out at temperatures of 50 degrees C-250 degrees C and pH of 8.5 - 10. The pH at a given temperature was controlled by adding different agents. Laboratory data indicate that the corrosion rate of carbon steel decreased as the pH increased under the test conditions and the highest corrosion rate was measured at 150 degrees C. This high corrosion rate may be related to high dissolution and instability of Fe oxide (Fe{sub 3}O{sub 4}) at 150 degrees C. It was also found that an addition of ethanolamine (ETA) to ammonia was more effectivefor anticorrosion than ammonia alone, and that mixed treatment reduced 50% of iron or more at pHs of 9.5 or higher, especially in the steam generator (SG) and the moisture separator and re-heater.

  7. 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)

  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. 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 τ R (λ) ˜ 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 τ R (λ) ≪ 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.

  10. 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

  11. 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

  12. Fluid source and pressure temperature conditions of high-salinity fluids in syn-tectonic veins from the Northeastern Apuan Alps (Northern Apennines, Italy)

    Science.gov (United States)

    Montomoli, Chiara; Ruggieri, Giovanni; Carosi, Rodolfo; Dini, Andrea; Genovesi, Marianna

    Structural studies on syn-tectonic veins cropping out in the northeastern sector of the Apuan Alps metamorphic complex (Northern Apennines, Italy) revealed two sets of veins: (1) type A fibrous veins within the “Scisti sericitici Formation”, related to a late-D1 tectonic phase; (2) B-veins, within the “Diaspri Formation” that developed between late-D1 and D2 tectonic phases. The mineralogy of the A (quartz, chlorite, hematite with minor amounts of apatite, allanite-(Ce), thorite and synchysite) and B-veins (quartz only) reflects the mineralogical composition of the host-rocks: quartz, chlorite, white mica and accessory minerals (apatite, zircon, titanite) occur in the “Scisti sericitici Formation”, while quartz is the main phase in the “Diaspri Formation”. The study of fluid inclusions trapped in quartz crystals of the syn-tectonic veins shows that the inclusions are always oversaturated in NaCl at room temperature and their salinities range from 29.5 to 37 wt.% NaCl equiv. The isochore of the earliest trapped fluid inclusions (type IA; primary inclusions in fiber quartz of A veins), coupled with mineralogical geothermometric data, constrains the pressure-temperature conditions to around 325-300 MPa and 370-380 °C during the late-D1 phase. Subsequent trapping of inclusion types IIA, IIB, IIIA, IIIB and VB in the two vein sets probably occurred during a pressure-temperature decrease (down to 220-245 MPa and 260-270 °C) at a lithostatic thermal gradient of 30 °C/km. Type IVB inclusions, on the other hand, were probably trapped at lower pressure (between lithostatic and hydrostatic conditions) during a transient pressure drop resulting from fault-valve action. SEM/EDS analyses on salts precipitated within opened inclusions confirmed the NaCl-rich compositions of the trapped fluids and also revealed the presence of minor amounts of Ca, K and Mn in the salts. A fluid circulation model, based on mineralogical and fluid inclusion data, was proposed for

  13. RESEARCH ON CHARACTERISTICS AND DIFFERENCE OF BAROMETRIC PRESSURE EFFECT ON WELL WATER LEVEL%井水位气压效应特征差异研究

    Institute of Scientific and Technical Information of China (English)

    黄仲; 张卫华; 王慧; 张辉

    2012-01-01

    On the basis of geological structure background, the feature of barometer change and the structure of well hole in well network of the Three Gorges area, the characteristics and differences of barometer change in well water level are analyzed and the relation between it and the parameter of physical mechanics in water-bearing stratum is also studied. The results show that the characteristics and differences of inverted barometer effect in well water level have a certain relation with the lithology of water-bearing stratum and the depth of well hole.%基于三峡井网所在地的地质构造背景、气压变化特征和井孔结构,分析了整个井网井水位气压变化特征及其差异,以及与含水层物理力学参数之间的关系等.分析结果表明,承压井水位气压效应特征差异与含水层岩性、井孔深度有关.

  14. Numerical Simulation of Thermal Stratification in Pressurized Water Reactor Pressurizer Surge Line under Transient Condition%瞬态工况下压水堆稳压器波动管热分层现象数值模拟

    Institute of Scientific and Technical Information of China (English)

    郭超; 温丽晶; 刘宇生; 张盼; 马帅

    2015-01-01

    T he thermal stratification under transient condition in pressurizer surge line of Qinshan Phase Ⅱ extension nuclear power project (2 × 650 MW PWR generator 4) was investigated by computational fluid dynamics program ANSYS/CFX .The whole and cross‐sectional thermal stratification transient analysis models for the pressurizer surge line were established ,and the heat stratified flow and heat transfer of the surge line were studied .The way of temperature growth is different between high‐and low‐temperature fluid layers in the same cross section . T he fluid temperature distribution has great difference in different cross sections , but the temperature difference first increases and then decreases in every cross section .The research results can provide a basis for subsequent analysis of thermal stress and lifespan .%利用计算流体动力学软件ANSYS/CFX ,对秦山核电二期扩建工程2×650 MW压水堆核电站四号机组核岛厂房的稳压器波动管进行了三维全尺寸非稳态计算。建立了波动管整体和不同截面的热分层瞬态,对管内热分层流动与换热进行了研究。研究结果表明:同一截面内高温层流体和低温层流体的升温方式不同;不同截面位置的管内流动温度分布特性差别较大,但均呈现分层流体温差先增大后减小的趋势。计算结果可为后续波动管热应力分析及寿命评价提供一定基础。

  15. Fault of the correction factor for pressure and temperature kPT in the atmospheric conditions of Dosimetric Calibration Lab. - LSCD of ININ - Mexico

    International Nuclear Information System (INIS)

    The realization of the operational quantities H*, Hp y/0 H'(0.07) for estimating the effective dose E, usually is done by measuring the air kerma Ka air within the field of ionizing radiation of interest and was subsequently applied appropriate conversion factors for both the quality of radiation and the operational quantity of interest. However, the SSDL in performing the Ka to environmental conditions of ININ (3000 m above sea level, P ∼ 710 hPa) with ionization chambers has found that the pressure correction factor and kPT temperature is not sufficient to correct the change in air density. Indeed, in the case of 60Co the discrepancy between the measurement of a primary standard graphite walls Ka (BEV CC01 be 131) and a side of the plastic walls (Exradin A12) is on the order of 0.4% for the case of the RX BIPM qualities to 100,135, 180 and 250 kV. It was found that for a camera model 30001 PTW (PMMA graphite wall) is needed an additional correction factor k PT ranging from 0.4% to 1.5%, correction factor calculated by MC simulation. For Sk of 125I brachytherapy sources was given an additional correction lower in 11% compared to conventional kPT value measured with a well chamber Standard Imaging HDR 1000 plus. Finally, it is in the process of studying the behavior of this additional correction factor to the case of 137Cs

  16. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    International Nuclear Information System (INIS)

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100–260 Torr pressure range and 1.5–2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (ηcoup) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance

  17. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    Science.gov (United States)

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (ηcoup) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  18. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions.

    Science.gov (United States)

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η(coup)) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  19. A detailed TEM and SEM study of Ni-base alloys oxide scales formed in primary conditions of pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sennour, Mohamed, E-mail: mohamed.sennour@ensmp.f [MINES, ParisTech, Centre des Materiaux, UMR CNRS 7633, B.P. 87, 91003 Evry Cedex (France); Marchetti, Loic; Martin, Frantz; Perrin, Stephane [CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, F-91191 Gif-sur-Yvette (France); Molins, Regine [MINES, ParisTech, Centre des Materiaux, UMR CNRS 7633, B.P. 87, 91003 Evry Cedex (France); Pijolat, Michele [LPMG-UMR CNRS 5148 , Centre SPIN, Ecole Nationale Superieure des Mines, 158 Cours Fauriel, F-42023 Saint-Etienne (France)

    2010-07-31

    The oxide film formed on nickel-based alloys in pressurized water reactors (PWR) primary coolant conditions (325 {sup o}C, aqueous media) is very thin, in the range of 1-100 nm thick, depending on the surface state and on the corrosion test duration. The nature and the structure of this scale have been investigated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). TEM observations revealed an oxide layer divided in two parts. The internal layer was mainly composed of a continuous spinel layer, identified as a mixed iron and nickel chromite (Ni{sub (1-x)}Fe{sub x}Cr{sub 2}O{sub 4}). Moreover, nodules of Cr{sub 2}O{sub 3}, with a size about 5 nm, were present at the interface between this spinel and the alloy. No chromium depletion was observed in the alloy, at the alloy/oxide interface. The external layer is composed of large crystallites corresponding to a spinel structure rich in iron (Ni{sub (1-z)}Fe{sub (2+z)}O{sub 4}) resulting from precipitation phenomena. SEM and TEM observations showed a link between the nucleation and/or the growth of crystallites of nickel ferrite and the crystallographic orientation of the substrate. A link between the presence of surface defects and the nucleation of the crystallites was also underlined by SEM observations. Partially hydrated nickel hydroxide, was also observed by TEM in the external scale. Based on these results, some considerations about the mechanism of formation of this oxide layer are discussed.

  20. A computational study of syngas auto-ignition characteristics at high-pressure and low-temperature conditions with thermal inhomogeneities

    KAUST Repository

    Pal, Pinaki

    2015-07-30

    A computational study was conducted to investigate the characteristics of auto-ignition in a syngas mixture at high-pressure and low-temperature conditions in the presence of thermal inhomogeneities. Highly resolved one-dimensional numerical simulations incorporating detailed chemistry and transport were performed. The temperature inhomogeneities were represented by a global sinusoidal temperature profile and a local Gaussian temperature spike (hot spot). Reaction front speed and front Damköhler number analyses were employed to characterise the propagating ignition front. In the presence of a global temperature gradient, the ignition behaviour shifted from spontaneous propagation (strong) to deflagrative (weak), as the initial mean temperature of the reactant mixture was lowered. A predictive Zel\\'dovich–Sankaran criterion to determine the transition from strong to weak ignition was validated for different parametric sets. At sufficiently low temperatures, the strong ignition regime was recovered due to faster passive scalar dissipation of the imposed thermal fluctuations relative to the reaction timescale, which was quantified by the mixing Damköhler number. In the presence of local hot spots, only deflagrative fronts were observed. However, the fraction of the reactant mixture consumed by the propagating front was found to increase as the initial mean temperature was lowered, thereby leading to more enhanced compression-heating of the end-gas. Passive scalar mixing was not found to be important for the hot spot cases considered. The parametric study confirmed that the relative magnitude of the Sankaran number translates accurately to the quantitative strength of the deflagration front in the overall ignition advancement. © 2015 Taylor & Francis

  1. Laser ablation for membrane processing of AlGaN/GaN- and micro structured ferroelectric thin film MEMS and SiC pressure sensors for extreme conditions

    Science.gov (United States)

    Zehetner, J.; Vanko, G.; Dzuba, J.; Ryger, I.; Lalinsky, T.; Benkler, Manuel; Lucki, Michal

    2015-05-01

    AlGaN/GaN based high electron mobility transistors (HEMTs), Schottky diodes and/or resistors have been presented as sensing devices for mechanical or chemical sensors operating in extreme conditions. In addition we investigate ferroelectric thin films for integration into micro-electro-mechanical-systems (MEMS). Creation of appropriate diaphragms and/or cantilevers out of SiC is necessary for further improvement of sensing properties of such MEMS sensors. For example sensitivity of the AlGaN/GaN based MEMS pressure sensor can be modified by membrane thickness. We demonstrated that a 4H-SiC 80μm thick diaphragms can be fabricated much faster with laser ablation than by electrochemical, photochemical or reactive ion etching (RIE). We were able to verify the feasibility of this process by fabrication of micromechanical membrane structures also in bulk 3C-SiC, borosilicate glass, sapphire and Al2O3 ceramic substrates by femtosecond laser (520nm) ablation. On a 350μm thick 4H-SiC substrate we produced an array of 275μm deep and 1000μm to 3000μm of diameter blind holes without damaging the 2μm AlN layer at the back side. In addition we investigated ferroelectric thin films as they can be deposited and micro-patterned by a direct UV-lithography method after the ablation process for a specific membrane design. The risk to harm or damage the function of thin films was eliminated by that means. Some defects in the ablated membranes are also affected by the polarisation of the laser light. Ripple structures oriented perpendicular to the laser polarisation promote creation of pin holes which would perforate a thin membrane. We developed an ablation technique strongly inhibiting formation of ripples and pin poles.

  2. A Parametric Study of the Impact of the Cooling Water Site Specific Conditions on the Efficiency of a Pressurized Water Reactor Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Mohamed M. A. Ibrahim

    2014-01-01

    Full Text Available In this study, the thermal analysis for the impact of the cooling seawater site specific conditions on the thermal efficiency of a conceptual pressurized water reactor nuclear power plant (PWR NPP is presented. The PWR NPP thermal performance depends upon the heat transfer analysis of steam surface condenser accounting for the key parameters such as the cooling seawater salinity and temperature that affect the condenser overall heat transfer coefficient and fouling factor. The study has two aspects: the first one is the impact of the temperature and salinity within a range of (290 K–310 K and 0.00–60000 ppm on the seawater thermophysical properties such as density, specific heat, viscosity, and thermal conductivity that reflect a reduction in the condenser overall heat transfer coefficient from 2.25 kW/m2 K to 1.265 kW/m2 K at temperature and salinity of 290 K and 0.00 ppm and also from 2.35 kW/m2 K to 1.365 kW/m2 K at temperature and salinity of 310 K and 60000 ppm, whereas the second aspect is the fouling factor variations due to the seawater salinity. The analysis showed that the two aspects have a significant impact on the computation of the condenser overall heat transfer coefficient, whereas the increase of seawater salinity leads to a reduction in the condenser overall heat transfer coefficient.

  3. Referenced dual pressure- and temperature-sensitive paint for digital color camera read out.

    Science.gov (United States)

    Fischer, Lorenz H; Karakus, Cüneyt; Meier, Robert J; Risch, Nikolaus; Wolfbeis, Otto S; Holder, Elisabeth; Schäferling, Michael

    2012-12-01

    The first fluorescent material for the referenced simultaneous RGB (red green blue) imaging of barometric pressure (oxygen partial pressure) and temperature is presented. This sensitive coating consists of two platinum(II) complexes as indicators and a reference dye, each of which is incorporated in appropriate polymer nanoparticles. These particles are dispersed in a polyurethane hydrogel and spread onto a solid support. The emission of the (oxygen) pressure indicator, PtTFPP, matches the red channel of a RGB color camera, whilst the emission of the temperature indicator [Pt(II) (Br-thq)(acac)] matches the green channel. The reference dye, 9,10-diphenylanthracene, emits in the blue channel. In contrast to other dual-sensitive materials, this new coating allows for the simultaneous imaging of both indicator signals, as well as the reference signal, in one RGB color picture without having to separate the signals with additional optical filters. All of these dyes are excitable with a 405 nm light-emitting diode (LED). With this new composite material, barometric pressure can be determined with a resolution of 22 mbar; the temperature can be determined with a resolution of 4.3 °C.

  4. The manifold pressure gauge in the automotive air conditioning failure diagnosis application analysis%歧管压力计在汽车空调故障诊断中的应用分析

    Institute of Scientific and Technical Information of China (English)

    王玉群; 马越群

    2011-01-01

    空调歧管压力计是对汽车空调系统整体工作性能进行分析的一种常用且有效的工具,它不仅应用于制冷剂的加注,而且也是一种故障诊断工具。文中就歧管压力计在空调系统中不同压力显示时的故障原因进行分析,为技术人员用歧管压力计对空调系统的运行状况及其故障进行诊断与排除提供相应的理论与实践借鉴,以保证或维持空调系统正常运行。%Air manifold pressure gauge is the overall performance of automotive air conditioning system for analysis of a common and effective tool,It is not only used in the filling of refrigerant,but also a troubleshooting tool.In this paper,manifold pressure gauge pressure in the air conditioning system is displayed in different analysis of the causes of failure,For the technical staff with the manifold pressure gauge on the air conditioning system operation and fault diagnosis and rule out the theory and practice to provide the corresponding reference,To ensure the normal operation or maintenance of air conditioning systems.

  5. High-sensitivity nuclear magnetic resonance at Giga-Pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions.

    Science.gov (United States)

    Meier, Thomas; Haase, Jürgen

    2014-01-01

    Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe. PMID:25350694

  6. 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

  7. 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

    -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...... 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...

  8. Dispersion in deep polar firn driven by synoptic-scale surface pressure variability

    Science.gov (United States)

    Buizert, Christo; Severinghaus, Jeffrey P.

    2016-09-01

    Commonly, three mechanisms of firn air transport are distinguished: molecular diffusion, advection, and near-surface convective mixing. Here we identify and describe a fourth mechanism, namely dispersion driven by synoptic-scale surface pressure variability (or barometric pumping). We use published gas chromatography experiments on firn samples to derive the along-flow dispersivity of firn, and combine this dispersivity with a dynamical air pressure propagation model forced by surface air pressure time series to estimate the magnitude of dispersive mixing in the firn. We show that dispersion dominates mixing within the firn lock-in zone. Trace gas concentrations measured in firn air samples from various polar sites confirm that dispersive mixing occurs. Including dispersive mixing in a firn air transport model suggests that our theoretical estimates have the correct order of magnitude, yet may overestimate the true dispersion. We further show that strong barometric pumping, such as at the Law Dome site, may reduce the gravitational enrichment of δ15N-N2 and other tracers below gravitational equilibrium, questioning the traditional definition of the lock-in depth as the depth where δ15N enrichment ceases. Last, we propose that 86Kr excess may act as a proxy for past synoptic activity (or paleo-storminess) at the site.

  9. Using smartphones' pressure sensors to measure vertical velocities in elevators, stairways and drones

    CERN Document Server

    Monteiro, Martin

    2016-01-01

    By means of smartphones' pressure sensors we measure vertical velocities of elevators, pedestrians climbing stairways and flying unmanned aerial vehicles (or \\textit{drones}). The barometric pressure obtained with the smartphone is related, thanks to the hydrostatic approximation, to the altitude of the device. From the altitude values, the vertical velocity is accordingly derived. The approximation considered is valid in the first hundreds meters of the inner layers of the atmosphere. Simultaneously to the pressure, the acceleration values, reported by the buit-in accelerometers, are also recorded. Integrating numerically the acceleration, vertical velocity and altitude are also obtained. We show that data obtained with the pressure sensor is considerable less noisy than that obtained with the accelerometer in the experiments proposed here. Accumulatioin of errors are also evident in the numerical integration of the acceleration values. The comparison with reference values taken from the architectural plans ...

  10. Blood pressure

    Science.gov (United States)

    ... the walls of the arteries is called blood pressure. Blood pressure is measured both as the heart contracts, which ... as it relaxes, which is called diastole. Normal blood pressure is considered to be a systolic blood pressure ...

  11. On Approach to Remove Abnormal Condition of VIOF-Series Intelligent Pressure/Differential Pressure Transmitter%V10F系列智能压力/差压变送器异常情况处理方法

    Institute of Scientific and Technical Information of China (English)

    孙妍

    2012-01-01

    Up to now from December 4,2010 when VIOF-series intelligent pressure/differential pressure transmitter(called Verabav flow gauge for short at the station),which integrates pressure,temperature,differential pressure and instantaneous delivery with its header displaying clearly and is easy to control on spot,came into use in Station-36 of Daniudi Gas Field,there is something wrong with the gauge such as its LCD assumes black screen suddenly,host computers of the header and self-control room monitoring have no display,and their instantaneous delivery shows zero or a box.The author finds out a proper and optimized maintenance method to remove the faults through sorting treatment and puts forward specifics to strengthen routine maintenance for the gauge.%V10F系列智能压力/差压变送器于2010年12月4日在大牛地气田36号站正式投入使用。该流量计集压力、温度、差压、瞬时流量为一体,表头显示清晰,现场操作简便,站场简称威力巴流量计。从投入使用至今,流量计出现了表头液晶显示屏黑、表头和自控室监控上位机不显示、上位机瞬时流量显示为零、上位机显示为方框等故障。针对故障,通过分类处理解决,得出了合理的、优化的故障维修方法,并提出了加强流量计日常维护的具体做法。

  12. First evidence of P21/n to P21/c structural transformation in pyroxene-type LiAlGe2O6 under high-pressure conditions

    Science.gov (United States)

    Nestola, Fabrizio; Artac, Andreas; Pippinger, Thomas; Miletich, Ronald; Secco, Luciano; Milani, Sula; Redhammer, Günther J.

    2015-08-01

    The high-pressure behavior of the pyroxene-type compound LiAlGe2O6, the unique representative of a P21/n-pyroxene, was investigated by in-situ X-ray diffraction and Raman spectroscopy on single-crystal samples hydrostatically pressurized in a diamond-anvil cell. The structure was found to undergo a first-order phase transition on compression, with a critical transition at 5.23±0.02 GPa. Together with a strong volume discontinuity of -ΔV/V0=-4.1% the transition shows a remarkable hysteresis loop over at least 0.70 GPa pressure interval. The bulk modulus of the low- and high-pressure polymorphs corresponds to K0=114(1) and 123(2) GPa, respectively, as described by a 2nd order Birch-Murnaghan equation of state. Based on the systematic extinctions the transition was identified as a P21/n-to-P21/c transformation. The mechanism of structural transformation was identified to be controlled by the stereochemistry of the Li atoms at the M2 site, which changes its coordination number from 5 to 6. The formation of new Li-O bonds involves the co-operative folding of Ge2O6-chains, which explains the anisotropy of axial elasticities and the spontaneous strain across the transformation. Simultaneously the distortion correction of AlO6 units associated with the transition further explains the preference of the P21/c structure under pressure.

  13. 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.

  14. 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, Cathryn H. [USDA Forest Service, New Ellenton, SC (United States); Tanner, George W. [USDA Forest Service, New Ellenton, SC (United States)

    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

  15. Bridging the pressure gap: In situ atomic-level investigations of model platinum catalyst surfaces under reaction conditions by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, B.J.

    1994-05-01

    Results of this thesis show that STM measurements can provide information about the surfaces and their adsorbates. Stability of Pt(110) under high pressures of H2, O2, and CO was studied (Chap. 4). In situ UHV and high vacuum experiments were carried out for sulfur on Pt(111) (Chap.5). STM studies of CO/S/Pt(111) in high CO pressures showed that the Pt substrate undergoes a stacking-fault-domain reconstruction involving periodic transitions from fcc to hcp stacking of top-layer atoms (Chap.6). In Chap.7, the stability of propylene on Pt(111) and the decomposition products were studied in situ with the HPSTM. Finally, in Chap.8, results are presented which show how the Pt tip of the HPSTM was used to locally rehydrogenate and oxidize carbonaceous clusters deposited on the Pt(111) surface; the Pt tip acted as a catalyst after activation by short voltage pulses.

  16. Acute effects of traditional Thai massage on cortisol levels, arterial blood pressure and stress perception in academic stress condition: A single blind randomised controlled trial.

    Science.gov (United States)

    Bennett, Surussawadi; Bennett, Michael John; Chatchawan, Uraiwon; Jenjaiwit, Patcharaporn; Pantumethakul, Rungthip; Kunhasura, Soontorn; Eungpinichpong, Wichai

    2016-04-01

    Traditional Thai massage (TTM) has been applied widely to promote relaxation. However, there is little evidence to support its efficacy on academic stress. A randomised controlled trial was performed to examine the acute effects of TTM on cortisol level, blood pressure, heart rate and stress perception in academic stress. This prospective trial included 36 physiotherapy students with a self perceived stress score of between 3 and 5. They were randomly allocated into the TTM (18 people) group or the control group (18 people). Saliva cortisol level, blood pressure, heart rate and stress perception rating were measured before and after the intervention. Both groups showed a significant reduction in cortisol level and heart rate when compared with baseline (p stress of TTM.

  17. Oxidation state and reducibility of supported VOx catalysts under ambient pressure and ultra-high-vacuum conditions

    OpenAIRE

    Klose, F.; Wolff, T; Suchorski, Y.; Weiß, H.

    2005-01-01

    Temperature programmed reduction/oxidation (TPR/TPO) and X-ray photoelectron spectroscopy (XPS) are two different fundamental techniques to acquire information on the oxidation state of metal oxide catalysts. In TPR experiments the consumption of hydrogen by a catalyst sample is measured as a function of the catalyst temperature. TPR works under ambient pressure, and the amount of hydrogen consumed can be correlated to the decrease of the oxidation state of the analyzed sample. In contrast to...

  18. Effects of Age, Gender, Bolus Condition, Viscosity, and Volume on Pharyngeal and Upper Esophageal Sphincter Pressure and Temporal Measurements during Swallowing

    Science.gov (United States)

    Butler, Susan G.; Stuart, Andrew; Castell, Donald; Russell, Gregory B.; Koch, Kenneth; Kemp, Shannon

    2009-01-01

    Purpose: The purpose of this study was to determine the effects of trial (i.e., Trial 1 vs. Trial 2); viscosity (i.e., saliva, thin, nectar-thick, honey-thick, and pudding-thick water); volume (i.e., 5 mL vs. 10 mL); age (i.e., young vs. older adults); and gender on pharyngeal (i.e., upper and lower) and upper esophageal sphincter (UES) pressures,…

  19. Research on Automotive Air Conditioning Refrigerant Filling Based on Manifold Pressure Gauge%基于歧管压力计的汽车空调制冷剂加注研究

    Institute of Scientific and Technical Information of China (English)

    朱亮亮; 陆健

    2016-01-01

    Automotive air conditioning refrigerant filling, is one of the key projects of automobile maintenance. Through the refrigerant properties and manifold pressure gauge principle of work introduction, refrigerant is filled in automotive air conditioning by manifold pressure gauge, and combines with the pressure detection function, refrigerant state to judge the refrigerant filling quantity; Furthermore qualitative analyzes the six kinds of common leak detection methods. In order to improve the utilization rate of automotive air conditioning, increase the comfort of occupants.%汽车空调系统制冷剂的加注,是汽车保养和维护的关键项目之一。通过制冷剂性能和歧管压力计工作原理的介绍,利用歧管压力计进行制冷剂的加注,并结合其压力检测功能、制冷剂状态等判断制冷剂加注量;并对常用的六种检漏方法进行了定性分析。以此提高汽车空调的利用率,增加驾乘人员的舒适性。

  20. 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.

  1. 壁面边界条件下氢气-空气预混燃烧的压力特性%Combustion Pressure Characteristics of Hydrogen-Air Pre-Mixture Under Wall Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    刘兴华; 张春龙; 刘福水; 孙作宇; 王汝维; 梁虹; 樊志强

    2013-01-01

    通过纹影测试的实验方法,在顶置点火定容燃烧弹中对壁面边界条件下的氢气-空气预混燃烧压力特性进行了实验研究,得出了不同燃烧当量比(0.6~2.0)、初始压力(0.1~0.3 MPa)、初始温度(300~450 K)下的氢气-空气预混燃烧过程中燃烧压力、最大燃烧压力以及最大燃烧压力升高率等参数的变化规律.结果表明,壁面边界条件下氢气-空气预混燃烧过程中的最大燃烧压力以及最大燃烧压力升高率均随着当量比的增大先增大再减小,均随初始压力的增大呈现出线性增长,随着初始温度的增大而呈现出线性减少.%By means of the Schlieren method,the combustion pressure characteristics of hydrogen-air pre-mixture under wall boundary conditions have been studied in a constant volume combustion bomb with the ignition point located in the upper part of the bomb.The combustion pressure,maxinum combustion pressure,and maximum rate of pressure rise were compared and analyzed at different fuel-equivalence ratios (0.6-2.0),initial pressures (0.1-0.3 MPa),and initial temperatures (300-450 K).The experimental results showed that both the maximum combustion pressure and the maximum rate of pressure rise of hydrogen-air pre-mixture under wall boundary conditions firstly increase and then decrease with the increase of equivalence ratio,and monotonously linearly increase with the increase of initial pressure and/or the decrease of initial temperature.

  2. 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

  3. A multiyear dust devil vortex survey using an automated search of pressure time series

    Science.gov (United States)

    Jackson, Brian; Lorenz, Ralph

    2015-03-01

    Dust devils occur in arid climates on the Earth and ubiquitously on Mars, where they likely dominate the supply of atmospheric dust and influence climate. Martian dust devils have been studied with a combination of orbiting and landed spacecraft, while most studies of terrestrial dust devils have involved manned monitoring of field sites, which can be costly both in time and personnel. As an alternative approach, we describe a multiyear in situ survey of terrestrial dust devils using pressure loggers deployed at El Dorado Playa in Nevada, USA, a site known for dust devil activity. Analogous to previous surveys for Martian dust devils, we conduct a posthoc analysis of the barometric data to search for putative dust devil pressure dips using a new automated detection algorithm. We investigate the completeness and false positive rates of our new algorithm and conduct several statistically robust analyses of the resulting population of dips. We also investigate possible seasonal, annual, and spatial variability of the putative dust devil dips, possible correlations with precipitation, and the influence of sample size on the derived population statistics. Our results suggest that large numbers of dips (>1000) collected over multiple seasons are probably required for accurate assessment of the underlying dust devil population. Correlating long-term barometric time series with other data streams (e.g., solar flux measurements from photovoltaic cells) can uniquely elucidate the natures and origins of dust devils, and accurately assessing their influence requires consideration of the full distribution of dust devil properties, rather than average values.

  4. Olmesartan vs ramipril in the treatment of hypertension and associated clinical conditions in the elderly: a reanalysis of two large double-blind, randomized studies at the light of the most recent blood pressure targets recommended by guidelines.

    Science.gov (United States)

    Omboni, Stefano; Malacco, Ettore; Mallion, Jean-Michel; Volpe, Massimo

    2015-01-01

    In this paper, we present the results of a reanalysis of the data of two large randomized, double-blind, parallel group studies with a similar design, comparing the efficacy of an angiotensin-receptor blocker (olmesartan medoxomil) with that of an angiotensin-converting enzyme inhibitor (ramipril), by applying two different blood pressure targets recently recommended by hypertension guidelines for all patients, irrespective of the presence of diabetes (hypertensive patients (hypertension type, diabetes status or other concomitant clinical conditions, or cardiovascular risk factors. In most cases, olmesartan provided better blood pressure control than ramipril. Olmesartan was significantly more effective than ramipril in male patients, in younger patients (aged 65-69 years), in those with metabolic syndrome, obesity, dyslipidemia, preserved renal function, diastolic ± systolic hypertension, and, in general, in patients with a high or very high cardiovascular risk. Interestingly, patients previously untreated or treated with two or more antihypertensive drugs showed a significantly larger response with olmesartan than with ramipril. Thus, our results confirm the good efficacy of olmesartan in elderly hypertensives even when new blood pressure targets for antihypertensive treatment are considered. Such results may be relevant for the clinical practice, providing some hint on the possible different response of elderly hypertensive patients to two different drugs acting on the renin-angiotensin system, when patients are targeted according to the blood pressure levels recommended by recent hypertension guidelines.

  5. 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.`

  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. Micro-Pressure Sensors for Future Mars Missions

    Science.gov (United States)

    Catling, David C.

    1996-01-01

    The joint research interchange effort was directed at the following principal areas: u further development of NASA-Ames' Mars Micro-meteorology mission concept as a viable NASA space mission especially with regard to the science and instrument specifications u interaction with the flight team from NASA's New Millennium 'Deep-Space 2' (DS-2) mission with regard to selection and design of micro-pressure sensors for Mars u further development of micro-pressure sensors suitable for Mars The research work undertaken in the course of the Joint Research Interchange should be placed in the context of an ongoing planetary exploration objective to characterize the climate system on Mars. In particular, a network of small probes globally-distributed on the surface of the planet has often been cited as the only way to address this particular science goal. A team from NASA Ames has proposed such a mission called the Micrometeorology mission, or 'Micro-met' for short. Surface pressure data are all that are required, in principle, to calculate the Martian atmospheric circulation, provided that simultaneous orbital measurements of the atmosphere are also obtained. Consequently, in the proposed Micro-met mission a large number of landers would measure barometric pressure at various locations around Mars, each equipped with a micro-pressure sensor. Much of the time on the JRI was therefore spent working with the engineers and scientists concerned with Micro-met to develop this particular mission concept into a more realistic proposition.

  8. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Vold, E.L.

    1997-03-01

    There is evidence for migration of tritiated water vapor through the tuff in the unsaturated zone from the buried disposal shafts located on a narrow mesa top at Area G, Los Alamos, NM. Field data are consistent with an effective in-situ vapor phase diffusion coefficient of 1.5x10{sup {minus}3} m{sup s}/s, or a factor of 60 greater than the binary diffusion coefficient for water vapor in air. A model is derived to explain this observation of anomolously large diffusion, which relates an effective vapor or gas phase diffusion coefficient in the fractured porous media to the subsurface propagation of atmospheric pressure fluctuations (barometric pumping). The near surface (unattenuated) diffusion coefficient is independent of mode period under the simplified assumptions of a complete {open_quote}mixing mechanism{close_quote} for the effective diffusion process. The unattenuated effective diffusion driven by this barometric pumping is proportional to an average media permeability times the sum of the square of pressure mode amplitudes, while the attenuation length is proportional to the squarer root of the product of permeability times mode period. There is evidence that the permeability needed to evaluate the pressure attenuation length is the in-situ value, approximately that of the matrix. The diffusion which results using Area G parameter values is negligible in the matrix but becomes large at the effective permeability of the fractured tuff matrix. The effective diffusion coefficient predicted by this model, due to pressure fluctuations and the observed fracture characteristics, is in good agreement with the observed in-situ diffusion coefficient for tritium field measurements. It is concluded that barometric pumping in combination with the enhanced permeability of the fractured media is a likely candidate to account for the observed in-field migration of vapor in the near surface unsaturated zone at Area G.

  9. 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

  10. Analysis of the Base of Designing Middle Pressure Section Process Conditions%中压吸收工艺条件设计基础浅析

    Institute of Scientific and Technical Information of China (English)

    刘慧莉; 叶陈

    2012-01-01

    At present, whatever technology in the world, urea production was divided into three phase. The first was synthesis, the second was recycle, and the last was evaporation & prilling. In Snamprogetti urea process, the middle pres- sure section, part of the recycle, was very important of urea plant. The base of designing the middle pressure section was discussed.%当代尿素生产,不论是采用哪种流程,基本上仍是由三个阶段组成,首先是合成工序;其次是分解并回收返回合成工序,称之为循环工序;最后是蒸发造粒工序。本文以Snamprogetti尿素工艺为例,介绍了循环工序中压部分的影响因素,并以此讨论了中压吸收工段工艺条件的设计基础。

  11. 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.)

  12. Examination of metal condition of the reactor pressure vessel and the core barrel at Rostov NPP unit 1 by nondestructive magnetic-hardness testing technology

    International Nuclear Information System (INIS)

    Surveillance programs of reactor pressure vessel (RPV) materials are necessary to assert the changes in the mechanical properties. The program can be achieved through 2 complementary ways: 1) mechanical tests on surveillance specimens irradiated inside the reactor vessel and 2) the use of specimen-free non-destructive methods that require in-site periodic routine inspection campaigns. This article is dedicated to the monitoring of mechanical properties of RPV steels through 2 specimen-free methods, one based on kinetic hardness and the other on magnetic structure analysis. The first method consists in refunding the complete diagram of penetration of a ball indentor into the investigated material, the adequate mathematical processing allows to draw standard diagram of mono-axial tension and to define strength characteristics. This method has been improved through the continuous registration of the indentation process, performed with the use of a 3-coordinates diagram: on-indentor loading, the material's surface indentation depth, and a current indentation velocity. Possessing an integral form, the diagram provides information about physical-mechanical properties of materials. Kinetic hardness method, however is unacceptable for monitoring clad RPV materials from PWR, as the presence of a stainless steel austenitic cladding whose thickness oscillates between 6-8 mm, closes access to investigated material. Magnetic structure analysis relies on a correlation between magnetic properties of RPV steels due to their ferromagnetic nature. Different comparisons between measured values of the coercive force and changes in yield stress are discussed. A correlation between ductile to brittle transition temperature and coercive force is shown for specimen of metal from welded joints. The measuring device (Magnetest) has been optimized for monitoring metal properties through a layer of austenitic cladding up to 10 mm thick

  13. Calcification and Growth of the Marine Coccolithophorid Emiliania huxleyi in Response to Elevated Partial Pressure of Carbon Dioxide and Low Phosphate Conditions

    Science.gov (United States)

    Faber, D. N.; Fabry, V. J.; Dickson, A. G.

    2004-12-01

    Atmospheric carbon dioxide (CO2) is expected to reach about 780 ppm by the year 2100, under the IS92a business-as-usual scenario. This expected increase will give rise to more than a threefold increase in surface ocean CO2 concentration, cause a drop in surface seawater pH of 0.4 units, and decrease the carbonate ion concentration by 55%, relative to pre-industrial values. Previous work demonstrated that the coccolithophorid Emiliania huxleyi shows a marked decrease in calcification rates in response to elevated CO2 under nutrient-replete and nitrogen-limited conditions. Here we investigate the response of E. huxleyi to increased pCO2 under phosphate limitation. Results from laboratory and mesocosm experiments indicate that E. huxleyi can outcompete other phytoplankton in communities that are under phosphate control. Moreover, E. huxleyi has higher calcification rates under phosphate limitation, and model studies suggest that low phosphate levels are necessary for E. huxleyi to form dense blooms in the NE Atlantic. We grew E. huxleyi cells in 8-L closed systems under low phosphate conditions at present day and elevated pCO2 concentrations. Cell growth, particulate inorganic carbon, particulate organic carbon, total alkalinity and total dissolved inorganic carbon were measured over time. Results will be discussed in relation to predicted changes in the oceanic CO2/carbonate system.

  14. Experimental device for chemical osmosis measurement on natural clay-rock samples maintained at in situ conditions: implications for formation pressure interpretations.

    Science.gov (United States)

    Rousseau-Gueutin, Pauline; de Greef, Vincent; Gonçalvès, Julio; Violette, Sophie; Chanchole, Serge

    2009-09-01

    In order to characterize the so-called coupled processes occurring in compacted clay rocks, the coupling coefficients must be identified. For this purpose, an original device which allows such measurement for undisturbed (natural) samples in their in situ conditions was developed. The present experimental device minimizes the fluid leaks improving the accuracy of the coupling parameter determination. Three chemical osmotic tests were performed on a cylindrical sample of Callovo-Oxfordian argilite. Room temperature variations during the chemical osmosis experiments required the implementation of temperature effects in the numerical model used for the interpretations. These variations offered the opportunity of an alternative method to estimate the compressibility of the fluid in the circuit connected to a measurement chamber located in the center of the sample. An osmotic efficiency of almost 0.2 for a concentration of 0.094 mol L(-1) is obtained for the Callovo-Oxfordian argilite. This value would explain only some part (approximately 0.10-0.15 MPa) of the overpressures (0.5-0.6 MPa) relative to the surrounding reservoirs measured in this formation. Others processes, such as thermo-osmosis, hydrodynamic boundary condition changes due to climate variations or creep behavior of the shale, could explain the remainder of the overpressures. PMID:19527907

  15. 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.

  16. 柴油机低振动目标的缸压边界条件研究%Study on Cylinder Pressure Boundary Condition with a Goal of Diesel's Low Vibration Character

    Institute of Scientific and Technical Information of China (English)

    高浩鹏; 黄映云; 田雪冰; 黄进明

    2012-01-01

    结合多体系统动力学与现代控制理论,建立了基于控制系统的柴油机多体系统动力学分析模型.综合柴油机性能和结构参数,在实验数据的基础上,以缸压为主要控制对象,实现了缸压的合理添加.在此基础上提出了以柴油机低振动目标特性的缸压添加方法,为共轨柴油机配机时兼顾低振动目标的实际配机过程奠定了基础.%Combined dynamics of multi-body systems theory with modern control theory, the multi-body dynamics model of diesel based on control system were established. Integrated the performance parameters and structure parameters, based on the experiment data, made cylinder pressure as main control object, the rational addition mode of cylinder pressure boundary condition was obtained. Based on the models, the method of addition of cylinder pressure was presented, which aimed to the low vibration character. And the method can be used to develop a base for the design of common-rail diesel ECU, which can be given consideration to both governor and vibration characters.

  17. Wind tunnel simulation of icing conditions on a NACA 63-415 blade profile found at Murdochville during the 2004-2005 measuring study of a Vesta V80 1.8 MW wind turbine; Simulation en soufflerie sur un profil NACA 63-415 des conditions de givrage relevees a Murchochville durant la campagne de mesure 2004-2005 selon une eolienne Vestas V80 de 1.8 MW

    Energy Technology Data Exchange (ETDEWEB)

    Hochart, C.; Fortin, G.; Perron, J. [Quebec Univ., Chicoutimi, PQ (Canada). Anti-Icing Materials International Laboratory; Ilinca, A. [Quebec Univ., Rimouski, PQ (Canada). Wind Energy Group

    2005-12-15

    Frost accumulation was measured on the NACA 63 415 blade profile of a Vesta V80, 1.8 MW wind turbine during refrigerated wind tunnel tests conducted at the Anti-Icing Materials International Laboratory (AMIL) in Chicoutimi, Quebec in late 2005. The purpose of the study was to reproduce frost conditions measured in Murdochville, Quebec during the period of December 2004 to May 2005. The loss of mass was measured and the form of frost deposited was examined along with the lift and augmentation of drag. Thirteen tests were conducted with various frost precipitation. The meteorological data that was collected included wind velocity, wind direction, air temperature, relative humidity, barometric pressure and solar radiation. The icing events resulting from freezing fog or wet snow were characterized by measuring the growth rate of ice, duration of the icing event and the ice accretion regime. Simulations of frost precipitation and moisture, as well as technical problems encountered during the tests were described. The experiment made it possible to evaluate the impact of ice and frost on wind turbine blade. The model was able to demonstrate the initial angle timing when the strength induced by the frost was too big compared to the strength of lift, and when the drag became negative, causing the wind turbine to stop turning. 38 refs., 27 tabs.

  18. Application of LITGs diagnostics to trace detection of NOx in high pressure combustors: a propedeutic study in a cell at controlled conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fantoni, R.; Giorgi, M. [ENEA, Centro Ricerche Frascati, Frascati RM (Italy). Dipt. Innovazione

    1999-07-01

    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 NO{sub 2} 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. [Italian] Il campo d'interferenza di due fasci laser, sia risonante che non con una transizione permessa in un mezzo, genera modulazion spaziali del suo indice di rifrazione complesso dette reticoli indotti da laser (Laser Induced Gratings con acronimo LIGs). Nel gas dopo l'eccitazione, il susseguente rilascio di energia genera le oscillazioni caratteristiche di un'onda acustica, mentre un rilascio di energia lento tende a sopprimere il contributo della componente acustica. Nel caso di un processo di termalizzazione multiplo, a cui contribuiscono diverse constanti di tempo, si possono osservare contemporaneamente contributi sia oscillanti che stazionari ai LITGs. Gli esperimenti sono stati effettuati con molecole di NO{sub 2} diluite in diversi

  19. 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.

  20. 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

  1. Peer Pressure

    Science.gov (United States)

    ... How Can I Help a Friend Who Cuts? Peer Pressure KidsHealth > For Teens > Peer Pressure Print A A A Text Size What's in ... She'd just had a big dose of peer pressure. Who Are Your Peers? When you were a ...

  2. 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.

  3. Origin of the change of the electrical and optical properties in shocked Al2O3 and prediction of an increase in electrical conductivity in MgSiO3 at pressure-temperature conditions of the Earth's D'' layer

    Science.gov (United States)

    He, L.; Tang, M. J.; Fang, Y.; Jing, F. Q.

    2008-08-01

    Shock-wave experiments of Al2O3 indicated the onset of an increase in electrical conductivity and observed the optical transparency loss at ~130 GPa. Here, based on first-principles calculations, we determine the pressure dependence of the band gap of perfect Al2O3 to 220 GPa, and investigate the optical absorption of Al2O3 without and with oxygen and aluminum vacancies within 220 GPa. Our results indicate that: 1) the onset of the conductivity increase is attributed to a band-gap decrease due to the Rh2O3(II)-CaIrO3 transition at ~130 GPa and ~1500 K; 2) this transition is not responsible for the transparency loss, but heterogeneous absorption in the visible-light region, induced by the +2 charge oxygen vacancy, should be a source of this phenomenon. The calculations of perfect MgSiO3, a material analogous to Al2O3, suggest that a perovskite to post-povskite transition in MgSiO3 at ~125 GPa and ~2500 K also yields a band-gap reduction. This causes an increase in electrical conductivity in MgSiO3 at pressure-temperature conditions of the Earth's D'' layer.

  4. Estimation of corrosion rate of Zr-2.5 wt%Nb alloy (Fugen pressure tube) under low-temperature, low-oxygen, and high-pH conditions

    International Nuclear Information System (INIS)

    Corrosion rate data for activated metal wastes are necessary for the prediction of the radiological impact of radioactive waste disposal. However, there are no such data available in the consideration of Zr-2.5 wt%Nb alloy, which is used in pressure tubes of the Fugen Nuclear Power Plant. Since the pressure tubes are destined for sub-surface disposal, it is necessary to obtain the corrosion rate of Zr-2.5 wt%Nb alloy under the disposal conditions. In this study, corrosion tests were conducted in high alkalinity and deoxidized water at 30degC by a gas-accumulating-type corrosion test. The corrosion rate decreased to 3.3-3.9 nm/y and the corrosion thickness increased in proportion to the cubic root of corrosion time until 24 months after the commencement of the test. The results indicate that the corrosion rate would decrease in proportion to the minus cubic root of corrosion time squared if the empirical corrosion characteristic that had been obtained in material research for light-water reactors is applicable. (author)

  5. 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

  6. Correlation Study on Psychological Health Conditions and Working Pressure of the Prison Police%监狱民警心理健康与工作压力及影响因素研究

    Institute of Scientific and Technical Information of China (English)

    姜燕琴

    2013-01-01

    用症状自评量表( SCL-90)与监狱压力源问卷对福建某监狱的360名民警进行施测,结果表明监狱民警心理健康水平显著低于全国常模,他们的工作压力比较大;从收入、年龄、工作年限等方面的进一步研究结果也表明,监狱民警收入较低的、年龄在30~45岁、工作年限为4~10年的群体工作压力大,其心理健康水平也较低,需通过提高民警自我调节能力、建立良好的社会支持系统等方式来提高民警心理健康水平。%An investigation into 360 prison guards in some prison in Fujian by symptom checklist-90 ( scl-90 ) and prison stressor questionnaire shows that the psychological health level of the prison police is significantly lower than the national norm, and that they work under high pressure as well. A further study from the perspectives of in-come, age, time of work and so on indicates that the prison police with lower income, aged between 30 and 45 years old and having worked for 4 to 10 years usually have lower psychological health level and higher work pres-sure. In order to improve this condition, some suggestions are put forward in this essay such as improving their self-regulation, establishing good social support system and so on.

  7. Pressure sensor

    Energy Technology Data Exchange (ETDEWEB)

    Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.; Nienstedt, Alex W.; Howell, Jr., Layton N.

    2015-09-29

    Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the need for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

  8. 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

  9. Evolution of amphibolite-facies structural features and boundary conditions for deformation during exhumation of high- and ultrahigh-pressure rocks, Nordøyane, Western Gneiss Region, Norway

    Science.gov (United States)

    Terry, Michael P.; Robinson, Peter

    2003-08-01

    Geologic mapping and structural analysis of Baltica basement and overlying thrust nappes have yielded a record of the late exhumation history of high-pressure rocks, where strain partitioning has preserved evidence for interpreting the evolution of late structural features. The earliest of these were extensional detachments juxtaposing eclogite-facies rocks against overlying amphibolite-facies rocks that show no evidence for eclogite-facies metamorphism. These early detachments are strongly overprinted and complexly folded, and they represent a phase of upper crustal extension that was active during continued convergence at deeper levels. Younger more localized mylonite zones formed synchronously with tubular, sheath, isoclinal, tight and open folding that shows a progression from WNW to ENE trends. The earliest mylonite zones, interpreted as originally subhorizontal, range in strike through a 20° angle from 110° to 90°. Later steeply dipping mylonite zones, formed under lower amphibolite-facies conditions, strike 75° and locally truncate earlier structures. The youngest mylonite zones, formed under lowest amphibolite conditions, strike 50° and truncate all earlier structures. Folds developed during this progression show the range in orientation from WNW to ENE reflected in the orientations of the mylonite zones that is interpreted to represent progressive evolution during top west shearing. These changes in orientation of the late structural features are interpreted to have been caused by changes in boundary conditions related to transtensional deformation during exhumation. L > S fabrics, absence of axial planar foliation, and chaotic orientations of axial surfaces of granulite to amphibolite-facies folds indicate formation in a constrictional strain field. This is also supported by estimates of the finite strain accumulated at ˜780°C and 45 km and similar observations by previous workers. Assuming a simple monoclinic deformation for transtension, strain

  10. Pressure sensors for petroleum wells

    International Nuclear Information System (INIS)

    A patent is claimed for a pressure sensor to be used in petroleum wells. Measurements can be performed under extreme temperature and pressure conditions. The system consists of a cell, containing an extensometric circuit, placed in a container and in contact with the pressure to be measured. The cell is formed by two sapphire half-shells. Their crystallographic orientation is chosen in order to obtain isotropy of stresses. The sensor is nearly independent from temperature fluctuations

  11. Spatial and Temporal Analysis of Hydrometeorological Conditions in the Valles Caldera, New Mexico during the North American Monsoon

    Science.gov (United States)

    Mendez-Barroso, L. A.; Rinehart, A. J.; Aragon, C. A.; Bisht, G.; Cardenas, M. B.; Engle, E.; Forman, B.; Frisbee, M.; Gutierrez-Jurado, H. A.; Hong, S.; Tai, K.; Wyckoff, R. L.; Vivoni, E. R.

    2005-12-01

    The hydrometeorological conditions of mountain environments in semiarid regions are poorly understood, particularly during the North American Monsoon. Although it is well known that the climate and hydrology of mountain ranges are dynamically distinct of surrounding lowlands, little quantitative observational data has been collected to assess the spatial and temporal variations in hydrometeorological conditions in these settings. Factors such as topographic position, vegetation type and soil properties have a strong influence on the hydrological response to atmospheric conditions. Similarly, landscape features such as relief and aspect can play a major role on the local meteorological conditions in mountainous environments. In order to better understand the relation between mountain hydrometeorology and topographic and ecological factors, a spatially extensive field campaign was carried out in the Valles Caldera National Preserve in the Jemez Mountains of northern New Mexico, USA. This region forms a portion of the headwaters of the Rio Grande and displays distinct hydrologic responses during the summer and winter seasons. A twelve day sampling period during the summer monsoon season (July to August 2005) was selected to observe the land-atmosphere interactions resulting from convective storms in the region. The hydrometeorological field campaign included seventy-one sampling sites where daily rainfall, meteorological variables (e.g. air temperature, relative humidity, wind speed and barometric pressure), volumetric soil moisture, and soil temperature were measured. Each site consisted of a one square meter plot that was characterized in term of terrain position, vegetation and surface properties. Likewise, daily gravimetric soil samples were taken in order to compare with the volumetric measurements inferred using an impedance probe. In this study, we present a preliminary analysis of the spatial and temporal distribution of soil and atmospheric variables during

  12. Abnormal pressure in hydrocarbon environments

    Science.gov (United States)

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  13. Carbon dioxide, temperature, salinity, and barometric pressure collected via surface underway survey from NOAA Ship McArthur II in the eastern North and South Pacific from 2006-07-30 to 2007-07-26 (NODC Accession 0084052)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0084052 includes underway chemical, meteorological, and physical data collected from NOAA Ship McARTHUR II in Coastal Waters of SE Alaska, Cordell...

  14. Chemical pressure

    OpenAIRE

    Hauser, Andreas; Amstutz, Nahid; Delahaye, Sandra; Sadki, Asmaâ; Schenker, Sabine; Sieber, Regula; Zerara, Mohamed

    2002-01-01

    The physical and photophysical properties of three classic transition metal complexes, namely [Fe(bpy)3]2+, [Ru(bpy)3]2+, and [Co(bpy)3]2+, can be tuned by doping them into a variety of inert crystalline host lattices. The underlying guest-host interactions are discussed in terms of a chemical pressure.

  15. Estimation of minimum or maximum pressure or temperature conditions in metamorphic rocks%变质作用温度与压力极限值的估算方法

    Institute of Scientific and Technical Information of China (English)

    吴春明; 陈泓旭

    2013-01-01

    压力的极小值或极大值.估算变质作用P-T的极限值,方法并不限于本文所述的例子.%When a mineral necessary in computing pressure (P) or temperature (T) conditions is absent,or compositions of the relevant mineral(s) were changed due to retrograde reactions in a metamorphic assemblage,and thus the true P and/or T cannot be determined,maximum or minimum P and/or T may be estimated and some examples are given in this work.(1) Extreme P or T conditions can be deciphered using phase diagrams of pure phases.For example,T of an assemblage containing sillimanite cannot be lower than 504 ± 20℃,whereas P of an assemblage containing andalusite cannot be higher than 0.375 ± 0.025GPa; (2) Some assemblages themselves indicate extreme P or T conditions.For example,the hypersthene + sillimanite + quartz assemblage can only be stable at P higher than 1.05GPa and the sapphirine + quartz assemblage cannot be stable lower than 1050℃,in high-and ultra-high temperature rocks ; (3) The equilibrium conditions of some reaction-out curves of mineral(s) also imply the limit of P or T conditions.For example,the reaction muscovite + quartz → K-feldspar + kyanite/sillimanite + H2O suggests that an assemblage containing muscovite cannot be stable at T higher than ca.650℃ at moderate P; (4) T yielded from solvus thermometry stands for the lower T limit of a unified solid solution phase when deriving the T conditions through combining the newly formed exsolution lamella and the relic matrix phase; (5) Metamorphic peak P-T conditions can only be determined on the basis of retrieving the chemical compositions of peak minerals when later retrograde reactions occurred and the peak minerals were destroyed partially; and (6) Maximum or minimum P conditions can be deciphered using model reactions of barometers when one phase is absent.For example,when rutile is absent in a metapelitic assemblage,maximum P can be estimated by considering that rutile is present because

  16. 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 NOβ UV intensity variation with the N and O atom densities

    Science.gov (United States)

    Boudam, M. K.; Saoudi, B.; Moisan, M.; Ricard, A.

    2007-03-01

    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 N_{2}^{+} 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 (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

  17. 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

  18. Pressurized hopper

    International Nuclear Information System (INIS)

    A Secure Automated Fuel Fabrication Line is being developed to reduce personnel exposure and to improve safeguards. Fertile and fissile fuel powders are blended in the line for making fuel pellets. A pressurized hopper was developed for use not only as a blender, but also as a storage and feeding device. It works with or without injection tubes to produce a well-blended powder with reduced agglomerate population. Results of blending experiments using dry Kaolin clay and Tempra pigment are given

  19. Parylene-on-oil packaging for long-term implantable pressure sensors.

    Science.gov (United States)

    Shapero, Aubrey M; Liu, Yang; Tai, Yu-Chong

    2016-08-01

    This paper reports and analyzes the feasibility study of a parylene-on-oil encapsulation packaging method of pressure sensors targeted for long-term implantation. Commercial barometric digital-output pressure sensors are enclosed in silicone oil and then encapsulated in situ with parylene-C or -D (PA-C, PA-D) chemical vapor deposition. Experimentally, sensors encapsulated with 30,000 cSt silicone oil and 27 μm PA-D show good performance for 6 weeks in 77 °C saline with >99 % of original sensitivity, corresponding to an extrapolated lifetime of around 21 months in 37 °C saline. This work shows that, with proper designs, such a packaging method can preserve the original pressure sensor sensitivity without offset, validated throughout accelerated lifetime tests. In experiments, wires on the prototypes are used for external electronics but it is found that they contributed to early failures, which would be absent in real wireless versions, indicating a potential for even longer lifetimes. Finally, a verified model is presented to predict the pressure sensor sensitivity of parylene-on-oil packaging with and without the presence of a bubble in the oil. PMID:27422106

  20. 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 ...

  1. Blood Pressure Quiz

    Science.gov (United States)

    ... page please turn Javascript on. Feature: High Blood Pressure Blood Pressure Quiz Past Issues / Fall 2011 Table of Contents ... About High Blood Pressure / Treatment: Types of Blood Pressure Medications / Blood Pressure Quiz Fall 2011 Issue: Volume 6 Number ...

  2. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... right away. continue How Do Doctors Measure Blood Pressure? Blood pressure readings are fast and painless. Blood pressure ... same age, height, and gender have lower blood pressure. Blood pressure between 90% and 95% of the normal ...

  3. High Pressure Biomass Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Pradeep K

    2016-07-29

    According to the Billion Ton Report, the U.S. has a large supply of biomass available that can supplement fossil fuels for producing chemicals and transportation fuels. Agricultural waste, forest residue, and energy crops offer potential benefits: renewable feedstock, zero to low CO2 emissions depending on the specific source, and domestic supply availability. Biomass can be converted into chemicals and fuels using one of several approaches: (i) biological platform converts corn into ethanol by using depolymerization of cellulose to form sugars followed by fermentation, (ii) low-temperature pyrolysis to obtain bio-oils which must be treated to reduce oxygen content via HDO hydrodeoxygenation), and (iii) high temperature pyrolysis to produce syngas (CO + H2). This last approach consists of producing syngas using the thermal platform which can be used to produce a variety of chemicals and fuels. The goal of this project was to develop an improved understanding of the gasification of biomass at high pressure conditions and how various gasification parameters might affect the gasification behavior. Since most downstream applications of synags conversion (e.g., alcohol synthesis, Fischer-Tropsch synthesis etc) involve utilizing high pressure catalytic processes, there is an interest in carrying out the biomass gasification at high pressure which can potentially reduce the gasifier size and subsequent downstream cleaning processes. It is traditionally accepted that high pressure should increase the gasification rates (kinetic effect). There is also precedence from coal gasification literature from the 1970s that high pressure gasification would be a beneficial route to consider. Traditional approach of using thermogravimetric analyzer (TGA) or high-pressure themogravimetric analyzer (PTGA) worked well in understanding the gasification kinetics of coal gasification which was useful in designing high pressure coal gasification processes. However, similar approach for

  4. High Pressure Biomass Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Pradeep K [Georgia Tech Research Corporation, Atlanta, GA (United States)

    2016-07-29

    According to the Billion Ton Report, the U.S. has a large supply of biomass available that can supplement fossil fuels for producing chemicals and transportation fuels. Agricultural waste, forest residue, and energy crops offer potential benefits: renewable feedstock, zero to low CO2 emissions depending on the specific source, and domestic supply availability. Biomass can be converted into chemicals and fuels using one of several approaches: (i) biological platform converts corn into ethanol by using depolymerization of cellulose to form sugars followed by fermentation, (ii) low-temperature pyrolysis to obtain bio-oils which must be treated to reduce oxygen content via HDO hydrodeoxygenation), and (iii) high temperature pyrolysis to produce syngas (CO + H2). This last approach consists of producing syngas using the thermal platform which can be used to produce a variety of chemicals and fuels. The goal of this project was to develop an improved understanding of the gasification of biomass at high pressure conditions and how various gasification parameters might affect the gasification behavior. Since most downstream applications of synags conversion (e.g., alcohol synthesis, Fischer-Tropsch synthesis etc) involve utilizing high pressure catalytic processes, there is an interest in carrying out the biomass gasification at high pressure which can potentially reduce the gasifier size and subsequent downstream cleaning processes. It is traditionally accepted that high pressure should increase the gasification rates (kinetic effect). There is also precedence from coal gasification literature from the 1970s that high pressure gasification would be a beneficial route to consider. Traditional approach of using thermogravimetric analyzer (TGA) or high-pressure themogravimetric analyzer (PTGA) worked well in understanding the gasification kinetics of coal gasification which was useful in designing high pressure coal gasification processes. However

  5. Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels

    Science.gov (United States)

    Som, Sanjoy M.; Buick, Roger; Hagadorn, James W.; Blake, Tim S.; Perreault, John M.; Harnmeijer, Jelte P.; Catling, David C.

    2016-06-01

    How the Earth stayed warm several billion years ago when the Sun was considerably fainter is the long-standing problem of the `faint young Sun paradox'. Because of negligible O2 and only moderate CO2 levels in the Archaean atmosphere, methane has been invoked as an auxiliary greenhouse gas. Alternatively, pressure broadening in a thicker atmosphere with a N2 partial pressure around 1.6-2.4 bar could have enhanced the greenhouse effect. But fossilized raindrop imprints indicate that air pressure 2.7 billion years ago (Gyr) was below twice modern levels and probably below 1.1 bar, precluding such pressure enhancement. This result is supported by nitrogen and argon isotope studies of fluid inclusions in 3.0-3.5 Gyr rocks. Here, we calculate absolute Archaean barometric pressure using the size distribution of gas bubbles in basaltic lava flows that solidified at sea level ~2.7 Gyr in the Pilbara Craton, Australia. Our data indicate a surprisingly low surface atmospheric pressure of Patm = 0.23 +/- 0.23 (2σ) bar, and combined with previous studies suggests ~0.5 bar as an upper limit to late Archaean Patm. The result implies that the thin atmosphere was rich in auxiliary greenhouse gases and that Patm fluctuated over geologic time to a previously unrecognized extent.

  6. 基于歧管压力表法对A30-10汽车空调实验台制冷故障的诊断分析%A Diagnostic Analysis of A30-10 Automotive Air Conditioning Experiment Table Refrigeration Fault Based on Manifold Pressure Gauge

    Institute of Scientific and Technical Information of China (English)

    江四; 孟杰

    2012-01-01

      In the air conditioning maintenance, fault diagnosis and detection, using manifold pressure gauge to make an analysis of refrigeration cycle fault is one of the most effective measures. With manifold pressure gauge the system can make the smelting device turn from high voltage side pressure to low voltage side pressure re⁃spectively with instrument instructions, which can determine the causes of the fault in order to use the right de⁃bugging methods. Based on the manifold pressure gauge method, a diagnostic analysis of A30-10 automotive air conditioning experiment table refrigeration fault is introduced in this paper.%  用歧管压力表能把制冷装置的高压侧与低压侧的压力分别用仪表指示出来,从而大致判定出故障的原因。本文采用歧管压力表法对A30-10汽车空调实验台进行了制冷故障的诊断分析。

  7. A Multi-Year Dust Devil Vortex Survey Using an Automated Search of Pressure Time-Series

    Science.gov (United States)

    Jackson, Brian K.; Lorenz, Ralph

    2014-11-01

    Dust devils occur in arid climates on the Earth and ubiquitously on Mars, where they likely dominate the supply of atmospheric dust and influence climate. Martian dust devils have been studied with a combination of orbiting and landed spacecraft, while most studies of terrestrial dust devils have involved manned monitoring of field sites, which can be costly both in time and personnel. As an alternative approach, we describe a multi-year in-situ survey of terrestrial dust devils using pressure loggers deployed at El Dorado Playa in Nevada, USA, a site known for dust devil activity. Analogous to previous surveys for Martian dust devils, we conduct a post-hoc analysis of the barometric data to search for putative dust devil pressure dips using a new automated detection algorithm. We investigate the completeness and false positive rates of our new algorithm and conduct several statistically robust analyses of the resulting population of dips. We also investigate seasonal, annual, and spatial variability of the putative dust devil dips, possible correlations with precipitation, and the influence of sample size on the derived population statistics. Our results suggest that large numbers of dips (> 1,000) collected over multiple seasons are probably required for accurate assessment of the underlying dust devil population. Correlating long-term barometric time-series with other data streams (e.g., solar flux measurements from photovoltaic cells) can uniquely elucidate the natures and origins of dust devils, and accurately assessing their influence requires consideration of the full distribution of dust devil properties, rather than average values. For example, our results suggest the dust flux from the average terrestrial devil is nearly 1,000 times smaller than the (more representative) population-weighted average flux. If applicable to Martian dust devils, such corrections may help resolve purported discrepancies between the dust fluxes estimated from dust devil studies

  8. Use of statistical design of experiments in the optimization of Ar-O2 low-pressure plasma treatment conditions of polydimethylsiloxane (PDMS) for increasing polarity and adhesion, and inhibiting hydrophobic recovery

    Science.gov (United States)

    Butrón-García, María Isabel; Jofre-Reche, José Antonio; Martín-Martínez, José Miguel

    2015-03-01

    Polydimethylsiloxane (PDMS) film was treated with RF low-pressure plasmas (LPPs) made of mixtures of oxygen and argon for increasing surface polarity, minimizing hydrophobic recovery (i.e. retard ageing) and increasing adhesion to acrylic adhesive tape for medical use. Statistical design of experiments has been used for determining the most influencing experimental parameters of the LPP treatment of PDMS. Water contact angle values (measured 24 h after treatment) and the O/C ratio obtained from XPS experiments were used as response variables. Working pressure was the most influencing parameter in LPP treatment of PDMS, and the duration of the treatment, the power and the oxygen-argon mixture composition determined noticeably its effectiveness. The optimal surface properties in PDMS and inhibited hydrophobic recovery were achieved by treatment with 93 vol% oxygen + 7 vol% argon LLP at low working pressure (300 mTorr), low power (25 W) and long duration of treatment (120 s).

  9. Electrical resistivity of YbRh{sub 2}Si{sub 2} and EuT{sub 2}Ge{sub 2} (T=Co,Cu) at extreme conditions of pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dionicio, G.A.

    2006-07-01

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh{sub 2}Si{sub 2}, EuCo{sub 2}Ge{sub 2}, and EuCu{sub 2}Ge{sub 2} 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, {rho}(T), from room temperature down to 100 mK. (orig.)

  10. Bulkhead pressure measurements in model fill pours

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, R.J.; Roettger, J.J.

    1984-08-01

    The results of a series of model stope pours designed to investigate working pressures on bulkheads during hydraulic pouring of classified tailings backfill are reported. Total bulkhead pressures and fill water pressures were monitored under the condition of a fully saturated backfill. Similitude of the model testing is discussed and equations are developed to estimate bulkhead pressures under prototype conditions. The model results show that good base drainage, combined with a bulkhead setback, can reduce the expected bulkhead pressures to values such that timber or concrete block structures should be capable of supporting a saturated backfill.

  11. Comparative Study of Pressure-Induced Germination of Bacillus subtilis Spores at Low and High Pressures

    OpenAIRE

    Wuytack, Elke Y.; Boven, Steven; Michiels, Chris W.

    1998-01-01

    We have studied pressure-induced germination of Bacillus subtilis spores at moderate (100 MPa) and high (500 to 600 MPa) pressures. Although we found comparable germination efficiencies under both conditions by using heat sensitivity as a criterion for germination, the sensitivity of pressure-germinated spores to some other agents was found to depend on the pressure used. Spores germinated at 100 MPa were more sensitive to pressure (>200 MPa), UV light, and hydrogen peroxide than were those g...

  12. Soil pressures at the cutting wheel and the pressure bulkhead of an EPB-shield

    OpenAIRE

    Bezuijen, Adam; Talmon, AM

    2014-01-01

    Soil pressureswere measured on both sides of the cutterwheel of an EPB-shield during tunnelling in saturated sand, using foam for soil conditioning. The measured pressures are compared with the pressures at the pressure bulkhead. The pressures are not purely hydrostatic but the results are also influenced by the yield strength of the foam mixture and the effective stresses. At the lowest positions, the sensors sometimes measured effective stresses. This led to peaks in the pressures measured....

  13. End-expiratory lung volume during mechanical ventilation: A comparison with reference values and the effect of positive end-expiratory pressure in intensive care unit patients with different lung conditions

    NARCIS (Netherlands)

    I.G. Bikker (Ido); J. van Bommel (Jasper); D. dos Reis Miranda; J. Bakker (Jan); D.A.M.P.J. Gommers (Diederik)

    2008-01-01

    textabstractIntroduction: Functional residual capacity (FRC) reference values are obtained from spontaneous breathing patients, and are measured in the sitting or standing position. During mechanical ventilation FRC is determined by the level of positive end-expiratory pressure (PEEP), and it is the

  14. 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 are also calculated With the general-purpose computer code COMMIX, which solves the exact mass conservation equation and Navier-Stokes equations. These solutions were compared with published experimental results, and agreement was good. The effect of turbulence on the pressure transient is discussed in the light of COMMIX calculational results

  15. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... your doctor prescribes it, medicine. What Is Blood Pressure? Blood pressure is the force of blood flow inside ... Will I Know if I Have High Blood Pressure? High blood pressure is a silent problem — you won't ...

  16. Understanding Blood Pressure Readings

    Science.gov (United States)

    ... What is the AHA recommendation for healthy blood pressure? This blood pressure chart reflects categories defined by the American ... unusually low blood pressure readings. How is high blood pressure diagnosed? Your healthcare providers will want to get ...

  17. High Blood Pressure

    Science.gov (United States)

    ... pressure and should be taken seriously. Over time, consistently high blood pressure weakens and damages ... of landmark NIH blood pressure study confirm that lower blood pressure target can reduce ...

  18. Technology in Building High Pressure Reinforced Concrete Penstocks with Complicated Geographic Conditions%复杂地质条件下建设高压钢筋混凝土岔管技术

    Institute of Scientific and Technical Information of China (English)

    郑晶星

    2014-01-01

    结合惠州抽水蓄能电站高压钢筋混凝土岔管的建设,对高水头抽水蓄能电站工程在复杂地质条件下钢筋混凝土岔管的布置及设计准则、设计理论及计算方法、防渗灌浆等相关技术问题进行了探讨。建设高压钢筋混凝土岔管,要满足抗抬理论和最小主应力准则,并合理控制高压岔管与相邻洞室的围岩渗透水力梯度,这样可以从整体上和宏观上控制、评估高压岔管的安全度。对于复杂的地质构造,通过高压灌浆技术进行工程处理,提高断层带的抗渗能力和承载能力,可满足高压岔管工程安全要求。%Combining with the construction of reinforced concrete high-pressure branch pipe in Huizhou Pumped Storage Power Station (HPSPS), it discussed the lay-out,design principles,design theories,calculation methodology and anti-penetration grouting and other related technical issues of reinforced concrete branch pipe of high head hydraulic pumped storage power station under complicated geographic situations. In the construction of reinforced concrete branch pipe,the anti-lift theory,the minimum principal stress criterion should be satisfied,and the hydraulic gradient of the high pressure bifurcated pipe wall rock adjacent caverns penetrate should be controlled reasonably,by means of which,the security of the high pressure branch could be controlled and assessed from overall and macro point of view. For a complex geological structure,the impermeability ca-pacity and anti-load capacity of the fault zone could be improved through the high-pressure grouting technology,which could meet the requirements of the high pressure branch engineering security.

  19. Review of research on characteristics of seepage-induced consolidation of soil under negative-pressure reinforcement conditions%负压条件下土体渗流固结特性研究综述

    Institute of Scientific and Technical Information of China (English)

    李平; 金奕潼; 赖建英; 刘伟

    2016-01-01

    This paper presents a review of literature related to project failures, variations of groundwater level, seepage characteristics of soil bodies, and mechanisms of seepage-induced consolidation during the reinforcement process under vacuum negative pressures. Although the seepage-induced vacuum consolidation method has been widely applied, theoretical study of the method lags far behind its practical application and still involves some disputes. Some key issues for future research regarding the method are presented, including new technology for measurement of groundwater levels under negative pressures, mechanisms of seepage-induced consolidation of soil, the effective transmission range of the vacuum degree, and the variation regularity of the zero-pressure surface.%针对真空负压加固过程中引起的工程破坏、地下水位变化规律、土体渗流特性、渗流固结机理等问题进行了分析,发现这种方法虽已得到广泛的应用,但其理论研究远落后于工程实践,并存在很多争议。指出今后需要研究的关键工作,如负压状态下地下水位测试新技术、土体渗流固结作用机理、真空度有效传递范围、“0”压面变化规律等。

  20. Pressure polymerization of polyester

    Science.gov (United States)

    Maurer, Charles J.; Shaw, Gordon; Smith, Vicky S.; Buelow, Steven J.; Tumas, William; Contreras, Veronica; Martinez, Ronald J.

    2000-08-29

    A process is disclosed for the preparation of a polyester polymer or polyester copolymer under superatmospheric pressure conditions in a pipe or tubular reaction under turbannular flow conditions. Reaction material having a glycol equivalents to carboxylic acid equivalents mole ratio of from 1.0:1 to 1.2:1, together with a superatmospheric dense gaseous medium are fed co-currently to the reactor. Dicarboxylic acid and/or diol raw materials may be injected into any of the reaction zones in the process during operation to achieve the overall desired mole ratio balance. The process operates at temperatures of from about 220.degree. C. to about 320.degree. C., with turbannular flow achieved before the polymer product and gas exit the reactor process. The pressure in the reaction zones can be in the range from 15 psia to 2500 psia. A polymer product having a DP of a greater than 40, more preferably at least about 70, is achieved by the transfer of water from the reacting material polymer melt to the gaseous medium in the reactor.

  1. [Pressure sores: management and treatment].

    Science.gov (United States)

    Goldschmidt, D; Seron, A; Jacquerye, A; Bustillo, A; Strale, H; Haubrechts, J; Del Marmol, V

    1997-09-01

    The global management of pressure sores is best ensured with a multidisciplinary approach. We present the experience of the "Groupe de Travail Escarres" (Pressure Sore Workgroup) which gathers physicians and nurses interested with this pathology. The majority of the decubitus ulcers will heal spontaneously with a conservative treatment only. This treatment typically aims at relieving the causes that lead to pressure sores, at eliminating the necrotic tissues, at obtaining favourable local conditions to allow wound healing and at controlling the health status of the patient. Surgical treatment of pressure sores is indicated when wound healing does not occur and when the health status of the patient is sufficiently good. Defect coverage is best carried out using myocutaneous flaps since their excellent blood supply allows a good cleansing of the wound. PMID:9411658

  2. Medications and Blood Pressure

    Science.gov (United States)

    ... Blood Pressure Tools & Resources Stroke More Medications and Blood Pressure Updated:Jul 6,2016 When your blood pressure ... was last reviewed on 08/04/2014. High Blood Pressure • Home • About High Blood Pressure (HBP) • Why HBP ...

  3. Physical Conditions in the Source Region of a Zebra Structure

    Science.gov (United States)

    Yasnov, L. V.; Karlický, M.; Stupishin, A. G.

    2016-07-01

    We analyze the physical conditions in the source region of a zebra structure, observed with the Ondřejov radiospectrograph during the 1 August 2010 solar flare. To determine the gyro-frequency harmonic numbers of the observed zebra lines, we compute the magnetic field strength, the electron density, and their spatial scales in the source region of the zebra structure. The region where the flare occurred is analyzed using EUV (171 Å and 335 Å) observations. To determine the conditions in the zebra source region, the magnetic field structure is reconstructed using observed photospheric magnetic field data. By computing the dependence of the magnetic field vs. height in this reconstruction and by comparing the magnetic field strength derived from the zebra structure, we determine the dependence of the electron density vs. height in the zebra source-region. We identify the loops where the zebra structure was generated at heights of about 2.5 - 3.3 Mm. Assuming the barometric law for the electron density, we determine the temperature in the zebra source-region to be T ≈ 2.0 × 104 K. Comparing the obtained values of the temperature and electron density in the zebra source-region with a model of the solar atmosphere, we find that the zebra structure was generated in the transition region, in agreement with our previous results.

  4. High Blood Pressure

    Science.gov (United States)

    ... normal blood pressure 140/90 or higher is high blood pressure Between 120 and 139 for the top number, ... prehypertension. Prehypertension means you may end up with high blood pressure, unless you take steps to prevent it. High ...

  5. High blood pressure - infants

    Science.gov (United States)

    National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics . ...

  6. High Blood Pressure Facts

    Science.gov (United States)

    ... Heart Disease Cholesterol Salt Million Hearts® WISEWOMAN High Blood Pressure Facts Recommend on Facebook Tweet Share Compartir ... facts about high blood pressure [PDF-255K] . High Blood Pressure in the United States About 70 million ...

  7. 手术室护士工作压力源与心理健康状况相关性研究%Working pressure source and psychologically healthy condition relevance research of the operating room nurse

    Institute of Scientific and Technical Information of China (English)

    邓新连; 赵砚霞; 王清香

    2010-01-01

    目的 了解手术室护士工作压力源与心理健康状况的相关性,并研究其应对策略,为提高手术室护士的心理健康水平提供依据.方法 本研究从本市4所医院在手术室工作一年以上的护士随机抽取70名作为调查对象,采用国内认可的SCL 90症状自评量表和护士工作压力源量表作为调查工具,将收集的资料通过SPSS 11.0软件包进行统计学分析和处理.结果 手术室护士工作压力状况显示在工作量及时间方面和压力总分有显著性差异.手术室护士心理健康状况与护理专业及工作方面相关性不大,在工作量及时间分配、工作环境及资源、患者护理及管理和人际关系等方面具有显著相关性.结论 诸多手术室工作压力方面的问题,以及一些引起手术室护士心理压力增加的相关因素存在,严重影响着手术室护士的心理健康,乃至影响护理质量.手术室的护理管理者应了解护士的心理需求,实行人性化管理,提供继续教育和参加应对工作压力能力训练的机会;护士要正确对待压力,提高心理防御能力,学会自我减压,保持良好的心理状态,以更高的热情投入到工作中去.%Objective To investigate the source of pressure on the operating room nurses and mental health relevance, and its research strategy,in order to improve the operating room nurses provide a basis for the level of mental health. Methods A three-city hospitals and 3 in the second hospital operating room nurses for more than one year of work, take a sample of the questionnaire method of payment, statistical data, analysis and processing. Results The operating room nurse pressure situation shows that secondary hospitals and tertiary hospitals in the workload and time pressure and total scores were significantly different. Operating room nurses and mental health care and professional work is not relevant in the allocation of time and workload, working environment and

  8. Chromosomal Conditions

    Science.gov (United States)

    ... labor & premature birth The newborn intensive care unit (NICU) Birth defects & other health conditions Loss & grief Tools & ... labor & premature birth The newborn intensive care unit (NICU) Birth defects & other health conditions Loss & grief Ask ...

  9. Truth conditions

    Institute of Scientific and Technical Information of China (English)

    张丽

    2009-01-01

    Truth conditions are used to determine whether a sentence is true or not in semantics. This article gives some examples both in English and Japanese to analyze truth conditions. Besides, the importance and the application of truth conditions are also mentioned.

  10. Preventing Pressure Sores

    Medline Plus

    Full Text Available ... Preventing Pressure Sores Preventing Pressure Sores Transition from Hospital to Home Transition from Hospital to Home Spasticity, Physical Therapy-Lokomat Spasticity, Physical ...

  11. Preventing Pressure Sores

    Medline Plus

    Full Text Available ... Injury 101 The Basics of Spinal Cord Injury Rehabilitation The Basics of Spinal Cord Injury Rehabilitation Preventing Pressure Sores Preventing Pressure Sores Transition from ...

  12. Sources of Pressure in Titan's Plasma Environment

    CERN Document Server

    Achilleos, N; Bertucci, C; Guio, P; Romanelli, N; Sergis, N

    2013-01-01

    In order to analyze varying plasma conditions upstream of Titan, we have combined a physical model of Saturn's plasmadisk with a geometrical model of the oscillating current sheet. During modeled oscillation phases where Titan is furthest from the current sheet, the main sources of plasma pressure in the near-Titan space are the magnetic pressure and, for disturbed conditions, the hot plasma pressure. When Titan is at the center of the sheet, the main source is the dynamic pressure associated with Saturn's cold, subcorotating plasma. Total pressure at Titan (dynamic plus thermal plus magnetic) typically increases by a factor of five as the current sheet center is approached. The predicted incident plasma flow direction deviates from the orbital plane of Titan by < 10 deg. These results suggest a correlation between the location of magnetic pressure maxima and the oscillation phase of the plasmasheet.

  13. Impact of Moisture on the Pressure Delivering Potential of Pressure Garments.

    Science.gov (United States)

    Macintyre, Lisa; Dahale, Monali; Rae, Michelle

    2016-01-01

    Pressure garments are the main method of treatment and prophylaxis for hypertrophic burn scars. The pressure they exert on the scarred skin prevents contractures forming, reduces the itchiness and pruritus associated with active hypertrophic scars, and is believed, by many, to hasten normalization of the scar tissue. The pressure exerted is believed to be critical to treatment success and can be predicted based on laboratory measurement of the fabric's tension profile. All previous research on the pressures delivered by pressure garments has been undertaken using dry fabrics in either laboratory or clinical conditions. However, many patients have complained of increased perspiration when wearing pressure garments, and many burn victims live and work in hot conditions where high levels of perspiration may be expected. This article investigated the impact of moisture content on fabric tension and thus the pressure exerting ability of pressure garments. Four different fabrics currently used in the construction of pressure garments were evaluated in seven different states of "wetness" from completely dry to completely saturated in water or artificial perspiration. Standard laboratory methods were used to measure the initial tension in fabrics and the tension after 11 cycles of extension. Pressures that would be exerted by these fabrics were calculated using the Laplace law. The results of this study showed that the tension, and therefore pressure delivering ability, of fabrics used in pressure garments was significantly reduced when they were wet but that the amount or type of "wetness" did not have a significant effect on pressure delivering ability. PMID:26171677

  14. 2010 weather and aeolian sand-transport data from the Colorado River corridor, Grand Canyon, Arizona

    Science.gov (United States)

    Dealy, Timothy P.; East, Amy E.; Fairley, Helen C.

    2014-01-01

    Measurements of weather parameters and aeolian sand transport were made in 2010 near selected archeological sites in the Colorado River corridor through Grand Canyon, Arizona. Data collected in 2010 indicate event- and seasonal-scale variations in rainfall, wind, temperature, humidity, and barometric pressure. Differences in weather patterns between 2009 and 2010 included a slightly later spring windy season, greater spring precipitation and annual rainfall totals, and a later onset and length of the reduced diurnal barometric-pressure fluctuations commonly associated with summer monsoon conditions. The increase in spring precipitation was consistent with the 2010 spring El Niño conditions compared to the 2009 spring La Niña conditions, whereas the subsequent transition to an El Niño-Southern Oscillation neutral phase appeared to delay the reduction in diurnal barometric fluctuations.

  15. Dismantling reactor pressure vessel internals at the Stade nuclear power station. Another milestone reached on the way to green field conditions; Rueckbau der Reaktordruckbehaelter-Einbauten im Kernkraftwerk Stade. Ein weiterer Meilenstein auf dem Weg zur gruenen Wiese ist realisiert

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Annette [AREVA NP GmbH, Erlangen (Germany); Knoll, Peter [Kernkraftwerk Stade GmbH und Co. oHG, Stade (Germany)

    2009-08-15

    In November 2003, the Stade nuclear power station (KKS) of E.ON Kernkraft GmbH was shut down for economic reasons. In its history of 31 years of operation up to that point in time KKS generated 152,460,660 MWh (gross) of electricity. From 1984 on, the reactor in addition supplied district heat to an adjacent saltworks. In early 2007 E.ON Kernkraftwerk GmbH, in the course of dismantling phase III, commissioned Areva NP to disassemble and package the reactor pressure vessel (RPV) internals. Within 17 months Areva did the entire engineering for this project, which was demanding in many respects. Over that period of time, detailed planning, drafting and licensing of the documents, design and manufacturing of the machines and facilities as well as their qualification, and personnel training were completed. Activities on site began in May 2008. Twelve months later, the RPV internals had been dismantled. This contractual milestone was reached even ahead of time. The shielding measures taken, ongoing optimization throughout the project phase, and the possibility to do without a containment allowed the estimated collective dose for these activities to be clearly underrun. The whole project was completed in late August 2009, and disassembly and packaging ready for repository storage of the RPV internals were carried out in a minimum of time. (orig.)

  16. "Keep the Beat": Healthy Blood Pressure Helps Prevent Heart Disease

    Science.gov (United States)

    ... Keep the Beat": Healthy Blood Pressure Helps Prevent Heart Disease Past Issues / Winter 2010 Table of Contents Your ... a condition that also increases the chance of heart disease and stroke. High blood pressure is especially common ...

  17. STUDY ON THE PRESSURE IN PLASMA ARC

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The axial pressure in plasma arc is measured under different conditions. The effects of the parameters, such as welding current, plasma gas flow rate, electrode setback and arc length, on the pressure in plasma arc are investigated and quantitative analyzed to explain the relationship between the quality of weld and the matching of parameters in plasma arc welding process.

  18. Brief Introduction to Digital Acupoint Pressure Therapy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ The Concept of Digital Acupoint Pressure Therapy The digital acupoint pressure therapy means that according to different diseases and the illness condition, the physician strikes, presses or taps the acupoints with hands on the patient's body surface to promote the circulation of qi and blood, thus making dysfunctions of certain organs or the affected areas return to normal.

  19. Bearing pad to pressure tube contact simulation

    Energy Technology Data Exchange (ETDEWEB)

    Talebi, F.; Behdadi, A.; Luxat, J.C., E-mail: farshat@mcmaster.ca, E-mail: behdada@mcmaster.ca, E-mail: luxatj@mcmaster.ca [McMaster Univ., Dept. of Engineering Physics, Hamilton, Ontario (Canada)

    2011-07-01

    Thermal creep strain deformation is a very important pressure tube failure mechanism. During a postulated LOCA (loss of coolant accident) with failure of emergency core injection sys- tem (ECIS), the fuel cladding temperature rapidly increases and the pressure tube becomes completely dry in a few seconds after flow stagnation occurs. Subsequently, the pressure tube circumference is heated by thermal radiation except at the spots where the bearing pads are in direct contact with the pressure tube. Therefore, the localized hot spots are developed on the pressure tube's inner surface under the bearing pads. The main objective of this paper is to evaluate the local thermal-mechanical deformation of a pressure tube in a CANDU reactor and to investigate the fuel channel integrity under localized contact between bearing pad and pressure tube. Furthermore, the mechanistic models are validated against the experimental works per- formed at WRL (Whiteshell research laboratory). Calculations are performed using the finite element method in which the heat, thermal mechanical and creep strain equations are solved, simultaneously. According to the experimental set up, the heat conduction from bearing pads to the inner surface of the pressure tube with appropriate convective and radiation boundary conditions has been simulated. Furthermore, the thermal creep strain deformation has been obtained for when the pressure tube is still under operational condition. It is observed that the pressure tube thermal strain will occur if sufficient high temperature is reached however, depending on the severity of flow degradation in the fuel channel, these localized hot spots could represent a potential creep strain failure of the pressure tube. Whether the pressure tube would fail at these hot spots before contacting the calandria tube depends on the localized temperature and experienced pressure transients. Sensitivity analysis is performed in order to evaluate the contact conductance

  20. Mineralogía y termo-barometría de los Complejos máficos Sol de Mayo y Suya Taco, Norte de las Sierras de Comechingones, Córdoba

    Directory of Open Access Journals (Sweden)

    Alina M. Tibaldi

    2008-03-01

    Full Text Available Este trabajo presenta un estudio detallado de la petrografía, mineralogía química y termo-barometría de dos complejos máficos que afloran al norte de la sierra de Comechingones. Se aplicaron un conjunto de termómetros y barómetros empíricos con el propósito de determinar los rangos de P y T absolutas de cristalización de estas rocas. Las temperaturas de equilibrio en pares de piroxenos (cpx-opx se estimaron usando tres termómetros independientes. Dos calibraciones termométricas (Wells 1977, Kretz 1982 dan resultados consistentes y razonables indicando que los piroxenos registran condiciones de cristalización magmática (920-1150ºC, mientras que la tercera calibración (Lindsley 1983 estima temperaturas muy inferiores. Esta discrepancia puede estar relacionada con el hecho de que la última calibración no sería aplicable a rocas que cristalizaron a partir de magmas ricos en hierro. Por su parte, la termometría Amph-Pl sugiere temperaturas de equilibrio comprendidas entre 750-850ºC, para composiciones típicas de núcleos, mientras que para composiciones representativas de los bordes de grano las temperaturas estimadas son significativamente inferiores (< 600ºC comportamiento que sugiere que el anfíbol cristalizó principalmente en una etapa post-magmática. Las temperaturas de intercambio para Fe-Mg entre opx-bt muestran que este par mineral se equilibró entre dos rangos térmicos bien definidos (430-650ºC y 740-1030ºC, lo que sugiere que las biotitas pueden haber cristalizado tanto en una etapa tardío magmática como post-magmática. Las formulaciones barométricas muestran cierta variabilidad en función de las calibraciones utilizadas, no obstante, sistemáticamente presentan un patrón de valores en el cual las presiones de equilibrio determinadas en el Complejo Suya Taco son inferiores (5,5 ± 1 kbar a las obtenidas en el Complejo Sol de Mayo (8 ± 1 kbar. En general, este resultado es consistente con las estimaciones

  1. Partial pressure gauges

    CERN Document Server

    Peter, G J

    2007-01-01

    The determination of partial pressures in vacuum systems is usually performed by mass spectrometers. The most common type is the QMS. Quadrupole mass spectrometers were developed decades ago and have been used by vacuum specialists as a diagnostic tool since then. In the first part of the paper the principles of these mass spectrometers are briefly reviewed together with the key features of the instruments. This is necessary to operate these instruments. In the second part the boundary conditions which arise from the application as residual gas analyser in UHV/XHV plants are described. These lead to special versions of mass spectrometers. Results obtained with these instruments and typical artefacts in mass spectra obtained in the UHV are discussed.

  2. Oil film pressure in hydrodynamic journal bearings

    OpenAIRE

    Valkonen, Antti

    2009-01-01

    Hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in various machines. Therefore, knowing the true operating conditions of hydrodynamic journal bearings is essential to machine design. Oil film pressure is one of the key operating parameters describing the operating conditions in hydrodynamic journal bearings. Measuring the oil film pressure in bearings has been a demanding task and theref...

  3. A global ground truth view of the lunar air pressure tide L2

    Science.gov (United States)

    Schindelegger, Michael; Dobslaw, Henryk

    2016-01-01

    A comprehensive model of the lunar air pressure tide L2 is developed on the basis of 2315 ground truth estimates from land barometers and moored buoys. Regional-scale features of the tide and its seasonal modulations are well resolved by the in situ scatter and gridded to a 2° mesh through multiquadric interpolation. The resulting climatologies serve as an independent standard to validate the lunar semidiurnal tidal signal that is present in ERA-Interim reanalysis products despite the absence of L2-related gravitational forcing mechanisms in the prescribed model physics. Inconsistencies between the reanalysis solution of the barometric lunar tide and its empirical account are generally small, yet when averaged over the period 1979-2010, ERA-Interim underestimates the 100 μbar open ocean tidal amplitude in the Tropics by up to 20 μbar and produces times of peak pressure that are too early by 10 lunar minutes. Large-amplitude features of the reanalysis tide off the coast of Alaska, the eastern U.S., and Great Britain are evidently spurious, introduced to the analysis system by assimilating marine pressure data at an invariant reference surface instead of properly accounting for vertical sensor movements associated with the M2 ocean tide. Additionally, a credible L2 signal is documented for the ERA-20C pilot reanalysis of the twentieth century. The fact that this model rests upon input data from mere surface observations provides an unambiguous indication that the lunar tidal oscillation in atmospheric analysis systems is closely tied to the assimilation of conventional pressure measurements from stations and marine objects.

  4. IIH with normal CSF pressures?

    Directory of Open Access Journals (Sweden)

    Soh Youn Suh

    2013-01-01

    Full Text Available Idiopathic intracranial hypertension (IIH is a condition of raised intracranial pressure (ICP in the absence of space occupying lesions. ICP is usually measured by lumbar puncture and a cerebrospinal fluid (CSF pressure above 250 mm H 2 O is one of the diagnostic criteria of IIH. Recently, we have encountered two patients who complained of headaches and exhibited disc swelling without an increased ICP. We prescribed acetazolamide and followed both patients frequently; because of the definite disc swelling with IIH related symptoms. Symptoms and signs resolved in both patients after they started taking acetazolamide. It is generally known that an elevated ICP, as measured by lumbar puncture, is the most important diagnostic sign of IIH. However, these cases caution even when CSF pressure is within the normal range, that suspicion should be raised when a patient has papilledema with related symptoms, since untreated papilledema may cause progressive and irreversible visual loss.

  5. Over-pressurized bioreactors: application to microbial cell cultures.

    Science.gov (United States)

    Lopes, Marlene; Belo, Isabel; Mota, Manuel

    2014-01-01

    In industrial biotechnology, microbial cultures are exposed to different local pressures inside bioreactors. Depending on the microbial species and strains, the increased pressure may have detrimental or beneficial effects on cellular growth and product formation. In this review, the effects of increased air pressure on various microbial cultures growing in bioreactors under moderate total pressure conditions (maximum, 15 bar) will be discussed. Recent data illustrating the diversity of increased air pressure effects at different levels in microbial cells cultivation will be presented, with particular attention to the effects of oxygen and carbon dioxide partial pressures on cellular growth and product formation, and the concomitant effect of oxygen pressure on antioxidant cellular defense mechanisms.

  6. Commonwealth Edison Company pressure locking test report

    Energy Technology Data Exchange (ETDEWEB)

    Bunte, B.D.; Kelly, J.F.

    1996-12-01

    Pressure Locking is a phenomena which can cause the unseating thrust for a gate valve to increase dramatically from its typical static unseating thrust. This can result in the valve actuator having insufficient capability to open the valve. In addition, this can result in valve damage in cases where the actuator capability exceeds the valve structural limits. For these reasons, a proper understanding of the conditions which may cause pressure locking and thermal binding, as well as a methodology for predicting the unseating thrust for a pressure locked or thermally bound valve, are necessary. This report discusses the primary mechanisms which cause pressure locking. These include sudden depressurization of piping adjacent to the valve and pressurization of fluid trapped in the valve bonnet due to heat transfer. This report provides a methodology for calculating the unseating thrust for a valve which is pressure locked. This report provides test data which demonstrates the accuracy of the calculation methodology.

  7. Commonwealth Edison Company pressure locking test report

    International Nuclear Information System (INIS)

    Pressure Locking is a phenomena which can cause the unseating thrust for a gate valve to increase dramatically from its typical static unseating thrust. This can result in the valve actuator having insufficient capability to open the valve. In addition, this can result in valve damage in cases where the actuator capability exceeds the valve structural limits. For these reasons, a proper understanding of the conditions which may cause pressure locking and thermal binding, as well as a methodology for predicting the unseating thrust for a pressure locked or thermally bound valve, are necessary. This report discusses the primary mechanisms which cause pressure locking. These include sudden depressurization of piping adjacent to the valve and pressurization of fluid trapped in the valve bonnet due to heat transfer. This report provides a methodology for calculating the unseating thrust for a valve which is pressure locked. This report provides test data which demonstrates the accuracy of the calculation methodology

  8. NDE and Stress Monitoring on Composite Overwrapped Pressure Vessels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Damage caused by composite overwrapped pressure vessels (COPVs) failure can be catastrophic. Thus, monitoring condition and stress in the composite overwrap,...

  9. High blood pressure medications

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007484.htm High blood pressure medicines To use the sharing features on this page, please enable JavaScript. Treating high blood pressure will help prevent problems such as heart disease, ...

  10. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... blood pressure with the development of a practical method to measure it. Physicians began to note associations between hypertension and risk of heart failure, stroke, and kidney failure. Although scientists had yet to prove that lowering blood pressure ...

  11. High blood pressure

    Science.gov (United States)

    ... you are at risk for: Bleeding from the aorta, the large blood vessel that supplies blood to ... tests Blood pressure check Blood pressure References American Diabetes Association. Standards of medical care in diabetes-2015 ...

  12. Blood Pressure Medicines

    Science.gov (United States)

    High blood pressure, also called hypertension, usually has no symptoms. But it can cause serious problems such as stroke, ... and kidney failure. If you cannot control your high blood pressure through lifestyle changes such as losing weight and ...

  13. Pressure vessel design manual

    CERN Document Server

    Moss, Dennis R

    2013-01-01

    Pressure vessels are closed containers designed to hold gases or liquids at a pressure substantially different from the ambient pressure. They have a variety of applications in industry, including in oil refineries, nuclear reactors, vehicle airbrake reservoirs, and more. The pressure differential with such vessels is dangerous, and due to the risk of accident and fatality around their use, the design, manufacture, operation and inspection of pressure vessels is regulated by engineering authorities and guided by legal codes and standards. Pressure Vessel Design Manual is a solutions-focused guide to the many problems and technical challenges involved in the design of pressure vessels to match stringent standards and codes. It brings together otherwise scattered information and explanations into one easy-to-use resource to minimize research and take readers from problem to solution in the most direct manner possible. * Covers almost all problems that a working pressure vessel designer can expect to face, with ...

  14. Atmospheric Pressure Indicator.

    Science.gov (United States)

    Salzsieder, John C.

    1995-01-01

    Discusses observable phenomena related to air pressure. Describes a simple, unobtrusive, semiquantitative device to monitor the changes in air pressure that are associated with altitude, using a soft-drink bottle and a balloon. (JRH)

  15. Relative microvascular pressure sensing

    Science.gov (United States)

    Choi, Min; Zemp, Roger

    2016-03-01

    Microcirculation may be characterized by the vascular pressure as it is influenced by pressure-driven perfusion. Crosssections of blood vessels can be visualized by photoacoustic imaging and compressing on vessels causes deformation. The photoacoustic signals of blood, when compressed to the point of vessel collapse, may or may not vanish depending on the buckling process it undergoes. We form relative pressure images of microvessels by tracking vessel collapse as a function of externally applied pressure using photoacoustic imaging.

  16. 内蒙古锡林浩特岩群岩石学特征及变质温压条件%Petrology and metamorphic temperature-pressure conditions of Xilinhot Group,Inner Mongolia,China

    Institute of Scientific and Technical Information of China (English)

    于洋; 葛梦春; 周文孝; 孙俊俊; 刘泽瑞

    2012-01-01

    Xilinhot Group,the supracrustal rock part of Xilin Gol complex,outcropped in the southeastern vicinity of Xilinhot of Inner Mongolia,is composed of gneiss with layers of amphibolite,magnetite quartzite and granofels.In this paper,we research the petrology of gneiss and amphibolite from Xilinhot Group.The amphibolites mainly contain amphibole+plagioclase assemblage;the sillimanite+K-feldspar assemblage appears in gneiss.The garnet from gneiss exhibits a pronounced compositional zoning resulting from progressive metamorphism.In such a case,the garnet domains that grow at peak metamorphic stage were chosen to calculate its formation temperatures.The p-T conditions of metabasic volcanic and metaclastic rocks penecontemporaneously formed in Xilinhot Group were appraised by garnet-biotite and hornblende-plagioclase geothermobarometry.The results suggest that the peak metamorphism of the Xilinhot Group had reached high amphibolite facies and its p-T ranges were 660-707 ℃and 0.5-0.6 GPa.Its metamorphic age is about 1000 Ma.The amphibolite facies metamorphism of Xilinhot Group might be result from the collision between Xilinhot microcontinent and other continental blocks.%锡林浩特岩群出露于内蒙古锡林浩特市东南部,指原锡林郭勒杂岩中表壳岩部分,为一套片麻岩夹层状斜长角闪岩、磁铁石英岩和变粒岩等的变质岩组合。选取岩群中片麻岩及斜长角闪岩进行岩石学及岩相学分析,其中斜长角闪岩主要矿物组合为角闪石+斜长石;片麻岩样品中见夕线石+钾长石矿物组合,石榴子石具明显进变质环带,所以在计算其形成条件时选取了生长于峰期变质阶段的特定部位。运用角闪石-斜长石、石榴子石-黑云母矿物温压计分别估算锡林浩特岩群中准同时形成的变质基性火山岩及变质碎屑岩的变质温压区间。综合二者计算结果,得锡林浩特岩群峰期变质温压条件为660~707℃,0.5~0.6GPa。变质达高角

  17. High-pressure apparatus

    NARCIS (Netherlands)

    Schepdael, van L.J.M.; Bartels, P.V.; Berg, van den R.W.

    1999-01-01

    The invention relates to a high-pressure device (1) having a cylindrical high-pressure vessel (3) and prestressing means in order to exert an axial pressure on the vessel. The vessel (3) can have been formed from a number of layers of composite material, such as glass, carbon or aramide fibers which

  18. STRESS ANALYSIS AND BURST PRESSURE DETERMINATION OF TWO LAYER COMPOUND PRESSURE VESSEL

    Directory of Open Access Journals (Sweden)

    HARERAM LOHAR

    2013-02-01

    Full Text Available Multilayer pressure vessel is designed to work under high-pressure condition. This paper introduces the stress analysis and the burst pressure calculation of a two-layer shrink fitted pressure vessel. In the shrink-fitting problems, considering long hollow cylinders, the plane strain hypothesis can be regarded as more natural. Generally hoops stress distribution is non-linear and sharply reduced toward the outer surface. By shrink fitting concentric shells towards the inner shells are placed in residual compression so that the initial compressive hoop stress must be relieved by internal pressure before hoop tensile stress are developed. Therefore the maximum hoop stress will be reduced, resulting more burst pressure. The analytical results of stress distribution and burst pressure is calculated and validated by ANSYS Workbench results.

  19. CONDITIONED SUPERPROCESSES

    Institute of Scientific and Technical Information of China (English)

    LICUNHANG; WURONG

    1997-01-01

    A class of superprocesses which dies out is investigated. Under the condition of norextinction, a new superprocess is COnstructed, its life time is infinite, and its distribution isdetermined by the moment function. Several limit theorems about this superprocess and its occulpation time process are obtained.

  20. Modeling Scala Media as a Pressure Vessel

    Science.gov (United States)

    Lepage, Eric; Olofsson, A.˚Ke

    2011-11-01

    The clinical condition known as endolymphatic hydrops is the swelling of scala media and may result in loss in hearing sensitivity consistent with other forms of low-frequency biasing. Because outer hair cells (OHCs) are displacement-sensitive and hearing levels tend to be preserved despite large changes in blood pressure and CSF pressure, it seems unlikely that the OHC respond passively to changes in static pressures in the chambers. This suggests the operation of a major feedback control loop which jointly regulates homeostasis and hearing sensitivity. Therefore the internal forces affecting the cochlear signal processing amplifier cannot be just motile responses. A complete account of the cochlear amplifier must include static pressures. To this end we have added a third, pressure vessel to our 1-D 140-segment, wave-digital filter active model of cochlear mechanics, incorporating the usual nonlinear forward transduction. In each segment the instantaneous pressure is the sum of acoustic pressure and global static pressure. The object of the model is to maintain stable OHC operating point despite any global rise in pressure in the third chamber. Such accumulated pressure is allowed to dissipate exponentially. In this first 3-chamber implementation we explore the possibility that acoustic pressures are rectified. The behavior of the model is critically dependent upon scaling factors and time-constants, yet by initial assumption, the pressure tends to accumulate in proportion to sound level. We further explore setting of the control parameters so that the accumulated pressure either stays within limits or may rise without bound.

  1. Fuzzy control applied to nuclear power plant pressurizer system

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Mauro V.; Almeida, Jose C.S., E-mail: mvitor@ien.gov.b, E-mail: jcsa@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    In a pressurized water reactor (PWR) nuclear power plants (NPPs) the pressure control in the primary loop is very important for keeping the reactor in a safety condition and improve the generation process efficiency. The main component responsible for this task is the pressurizer. The pressurizer pressure control system (PPCS) utilizes heaters and spray valves to maintain the pressure within an operating band during steady state conditions, and limits the pressure changes, during transient conditions. Relief and safety valves provide overpressure protection for the reactor coolant system (RCS) to ensure system integrity. Various protective reactor trips are generated if the system parameters exceed safe bounds. Historically, a proportional-integral derivative (PID) controller is used in PWRs to keep the pressure in the set point, during those operation conditions. The purpose of this study has two main goals: first is to develop a pressurizer model based on artificial neural networks (ANNs); second is to develop a fuzzy controller for the PWR pressurizer pressure, and compare its performance with the P controller. Data from a simulator PWR plant was used to test the ANN and the controllers as well. The reference simulator is a Westinghouse 3-loop PWR plant with a total thermal output of 2785 MWth. The simulation results show that the pressurizer ANN model response are in reasonable agreement with the simulated power plant, and the fuzzy controller built in this study has better performance compared to the P controller. (author)

  2. Low Pressure Evidence of High Pressure Shock: Thermal Histories and Annealing in Shocked Meteorites

    Science.gov (United States)

    Sharp, T. G.; Hu, J.

    2016-08-01

    In this study we look at the mineralogy associated with shock veins in several highly shocked L chondrites to better understand shock conditions and the importance of thermal history in creating and destroying high-pressure minerals.

  3. An Alternative Flight Software Trigger Paradigm: Applying Multivariate Logistic Regression to Sense Trigger Conditions Using Inaccurate or Scarce Information

    Science.gov (United States)

    Smith, Kelly M.; Gay, Robert S.; Stachowiak, Susan J.

    2013-01-01

    In late 2014, NASA will fly the Orion capsule on a Delta IV-Heavy rocket for the Exploration Flight Test-1 (EFT-1) mission. For EFT-1, the Orion capsule will be flying with a new GPS receiver and new navigation software. Given the experimental nature of the flight, the flight software must be robust to the loss of GPS measurements. Once the high-speed entry is complete, the drogue parachutes must be deployed within the proper conditions to stabilize the vehicle prior to deploying the main parachutes. When GPS is available in nominal operations, the vehicle will deploy the drogue parachutes based on an altitude trigger. However, when GPS is unavailable, the navigated altitude errors become excessively large, driving the need for a backup barometric altimeter to improve altitude knowledge. In order to increase overall robustness, the vehicle also has an alternate method of triggering the parachute deployment sequence based on planet-relative velocity if both the GPS and the barometric altimeter fail. However, this backup trigger results in large altitude errors relative to the targeted altitude. Motivated by this challenge, this paper demonstrates how logistic regression may be employed to semi-automatically generate robust triggers based on statistical analysis. Logistic regression is used as a ground processor pre-flight to develop a statistical classifier. The classifier would then be implemented in flight software and executed in real-time. This technique offers improved performance even in the face of highly inaccurate measurements. Although the logistic regression-based trigger approach will not be implemented within EFT-1 flight software, the methodology can be carried forward for future missions and vehicles.

  4. An Alternative Flight Software Paradigm: Applying Multivariate Logistic Regression to Sense Trigger Conditions using Inaccurate or Scarce Information

    Science.gov (United States)

    Smith, Kelly; Gay, Robert; Stachowiak, Susan

    2013-01-01

    In late 2014, NASA will fly the Orion capsule on a Delta IV-Heavy rocket for the Exploration Flight Test-1 (EFT-1) mission. For EFT-1, the Orion capsule will be flying with a new GPS receiver and new navigation software. Given the experimental nature of the flight, the flight software must be robust to the loss of GPS measurements. Once the high-speed entry is complete, the drogue parachutes must be deployed within the proper conditions to stabilize the vehicle prior to deploying the main parachutes. When GPS is available in nominal operations, the vehicle will deploy the drogue parachutes based on an altitude trigger. However, when GPS is unavailable, the navigated altitude errors become excessively large, driving the need for a backup barometric altimeter to improve altitude knowledge. In order to increase overall robustness, the vehicle also has an alternate method of triggering the parachute deployment sequence based on planet-relative velocity if both the GPS and the barometric altimeter fail. However, this backup trigger results in large altitude errors relative to the targeted altitude. Motivated by this challenge, this paper demonstrates how logistic regression may be employed to semi-automatically generate robust triggers based on statistical analysis. Logistic regression is used as a ground processor pre-flight to develop a statistical classifier. The classifier would then be implemented in flight software and executed in real-time. This technique offers improved performance even in the face of highly inaccurate measurements. Although the logistic regression-based trigger approach will not be implemented within EFT-1 flight software, the methodology can be carried forward for future missions and vehicles

  5. High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

    2014-01-01

    Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

  6. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, Barometric pressure sensor and other instruments from ROGER REVELLE in the Indian Ocean and Southern Oceans from 2008-02-04 to 2008-03-17 (NODC Accession 0108118)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0108118 includes discrete sample and profile data collected from ROGER REVELLE in the Indian Ocean and Southern Oceans (> 60 degrees South) from...

  7. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from THALASSA in the North Atlantic Ocean from 2012-08-19 to 2012-09-10 (NODC Accession 0117712)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117712 includes Surface underway, chemical, meteorological and physical data collected from THALASSA in the North Atlantic Ocean from 2012-08-19 to...

  8. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the Bell M. Shimada in the Coastal Waters of SE Alaska, Cordell Bank National Marine Sanctuary and others from 2011-06-27 to 2011-08-31 (NODC Accession 0115710)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115710 includes chemical, meteorological, physical and underway - surface data collected from Bell M. Shimada in the Coastal Waters of SE Alaska,...

  9. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the AURORA AUSTRALIS in the Great Australian Bight, Indian Ocean and others from 1992-10-19 to 2001-12-12 (NODC Accession 0115153)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115153 includes chemical, meteorological, physical and underway - surface data collected from AURORA AUSTRALIS in the Great Australian Bight, Indian...

  10. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from OSCAR DYSON in the Bering Sea, Gulf of Alaska and North Pacific Ocean from 2014-03-03 to 2014-08-13 (NCEI Accession 0144980)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144980 includes Surface underway data collected from OSCAR DYSON in the Bering Sea, Gulf of Alaska and North Pacific Ocean from 2014-03-03 to...

  11. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the EXPLORER OF THE SEAS in the Caribbean Sea, Gulf of Mexico and North Atlantic Ocean from 2005-01-02 to 2005-12-18 (NODC Accession 0109924)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0109924 includes biological, chemical, meteorological, physical and underway - surface data collected from EXPLORER OF THE SEAS in the Caribbean Sea,...

  12. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the EXPLORER OF THE SEAS in the Caribbean Sea, Gulf of Mexico and others from 2006-01-15 to 2006-12-24 (NODC Accession 0109925)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0109925 includes biological, chemical, meteorological, physical and underway - surface data collected from EXPLORER OF THE SEAS in the Caribbean Sea,...

  13. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the SKOGAFOSS in the North Atlantic Ocean and Stellwagen Bank National Marine Sanctuary from 2007-01-07 to 2007-06-04 (NODC Accession 0112887)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112887 includes chemical, meteorological, physical and underway - surface data collected from SKOGAFOSS in the North Atlantic Ocean and Stellwagen...

  14. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the JAMES CLARK ROSS in the Arctic Ocean, Barents Sea and others from 2012-11-15 to 2013-08-16 (NODC Accession 0115256)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115256 includes chemical, meteorological, physical and underway - surface data collected from JAMES CLARK ROSS in the Arctic Ocean, Barents Sea,...

  15. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from ROGER REVELLE in the Indian Ocean, South Pacific Ocean and others from 2007-02-04 to 2007-03-16 (NCEI Accession 0144252)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144252 includes Surface underway data collected from ROGER REVELLE in the Indian Ocean, South Pacific Ocean, Southern Oceans (> 60 degrees South)...

  16. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the Atlantic Companion in the Irish Sea and St. George's Channel and North Atlantic Ocean from 2011-12-05 to 2011-12-13 (NODC Accession 0115715)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115715 includes Surface underway, chemical, meteorological and physical data collected from Atlantic Companion in the Irish Sea and St. George's...

  17. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the Atlantic Companion in the Inner Sea - West Coast Scotland, Irish Sea and St. George's Channel and North Atlantic Ocean from 2006-06-11 to 2007-11-05 (NODC Accession 0115226)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115226 includes chemical, meteorological, physical and underway - surface data collected from Atlantic Companion in the Inner Sea - West Coast...

  18. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the SKOGAFOSS in the North Atlantic Ocean, North Greenland Sea and Stellwagen Bank National Marine Sanctuary from 2006-03-15 to 2007-01-04 (NODC Accession 0112932)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112932 includes chemical, meteorological, physical and underway - surface data collected from SKOGAFOSS in the North Atlantic Ocean, North Greenland...

  19. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the SKOGAFOSS in the Gulf of St. Lawrence, Labrador Sea and others from 2005-01-07 to 2005-12-06 (NODC Accession 0112931)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112931 includes chemical, meteorological, physical and underway - surface data collected from SKOGAFOSS in the Gulf of St. Lawrence, Labrador Sea,...

  20. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the EXPLORER OF THE SEAS in the Caribbean Sea, Gulf of Mexico and North Atlantic Ocean from 2004-01-03 to 2005-01-02 (NODC Accession 0081033)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0081033 includes biological, chemical, meteorological, physical and underway - surface data collected from EXPLORER OF THE SEAS in the Caribbean Sea,...

  1. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the EXPLORER OF THE SEAS in the Bay of Fundy, Caribbean Sea and others from 2006-12-31 to 2007-12-01 (NODC Accession 0081035)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0081035 includes biological, chemical, meteorological, physical and underway - surface data collected from EXPLORER OF THE SEAS in the Bay of Fundy,...

  2. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the EXPLORER OF THE SEAS in the Caribbean Sea, Gulf of Mexico and North Atlantic Ocean from 2003-02-08 to 2004-01-03 (NODC Accession 0081032)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0081032 includes biological, chemical, meteorological, physical and underway - surface data collected from EXPLORER OF THE SEAS in the Caribbean Sea,...

  3. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the SKOGAFOSS in the North Atlantic Ocean, North Greenland Sea and Stellwagen Bank National Marine Sanctuary from 2004-02-17 to 2005-01-06 (NODC Accession 0112930)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112930 includes chemical, meteorological, physical and underway - surface data collected from SKOGAFOSS in the North Atlantic Ocean, North Greenland...

  4. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the SKOGAFOSS in the North Atlantic Ocean and Stellwagen Bank National Marine Sanctuary from 2003-11-20 to 2003-12-21 (NODC Accession 0112929)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112929 includes chemical, meteorological, physical and underway - surface data collected from SKOGAFOSS in the North Atlantic Ocean and Stellwagen...

  5. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from NOAA Ship RONALD H. BROWN in the North Atlantic Ocean, North Pacific Ocean and others from 2008-01-22 to 2009-01-11 (NODC Accession 0109930)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0109930 includes biological, chemical, meteorological, physical and underway - surface data collected from NOAA Ship RONALD H. BROWN in the North...

  6. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the KEIFU MARU in the East China Sea (Tung Hai), North Pacific Ocean and others from 2001-01-20 to 2011-03-22 (NODC Accession 0081044)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0081044 includes chemical, meteorological, physical and underway - surface data collected from KEIFU MARU in the East China Sea (Tung Hai), North...

  7. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from Trans Future 5 in the Bass Strait, Coral Sea and others from 2012-01-16 to 2012-12-07 (NCEI Accession 0144347)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144347 includes Surface underway data collected from Trans Future 5 in the Bass Strait, Coral Sea, East China Sea (Tung Hai), Inland Sea (Seto...

  8. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from Trans Future 5 in the Bass Strait, Coral Sea and others from 2006-06-27 to 2006-12-09 (NCEI Accession 0144357)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144357 includes Surface underway data collected from Trans Future 5 in the Bass Strait, Coral Sea, North Pacific Ocean, Philippine Sea, Solomon Sea,...

  9. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the RONALD H. BROWN in the North Atlantic Ocean and South Atlantic Ocean from 2013-07-18 to 2013-10-02 (NODC Accession 0117699)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117699 includes Surface underway, chemical, meteorological and physical data collected from RONALD H. BROWN in the North Atlantic Ocean and South...

  10. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the KA'IMIMOANA in the North Pacific Ocean and South Pacific Ocean from 2010-01-06 to 2010-09-17 (NODC Accession 0115170)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115170 includes chemical, meteorological, physical and underway - surface data collected from KA'IMIMOANA in the North Pacific Ocean and South...

  11. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the Drifting Buoy in the Indian Ocean, South Atlantic Ocean and others from 2001-11-20 to 2007-05-08 (NODC Accession 0117495)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117495 includes Surface underway, biological, chemical, meteorological and physical data collected from Drifting Buoy in the Indian Ocean, South...

  12. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from RIO BLANCO in the English Channel, Mediterranean Sea and others from 2009-12-13 to 2010-12-14 (NODC Accession 0117291)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0117291 includes Surface underway data collected from RIO BLANCO in the English Channel, Mediterranean Sea, North Atlantic Ocean, South Atlantic...

  13. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from ROGER REVELLE in the South Pacific Ocean and Southern Oceans from 2005-01-06 to 2005-02-19 (NCEI Accession 0144243)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144243 includes Surface underway data collected from ROGER REVELLE in the South Pacific Ocean and Southern Oceans (> 60 degrees South) from...

  14. 第一代鲁奇炉在褐煤加压气化中的运行状况及技术改进%Running Condition and Technology Improvement in Brown Coal Pressure Gasification of the First Generation of Lurgi Furnace

    Institute of Scientific and Technical Information of China (English)

    王朝文

    2012-01-01

    The running conditions and problems of the first generation of Lurgi Furnace for ammonia preparation by using of low - quality brown coal pressurized gasification was introduced. The main problems and corresponding technology improvements of the first generation of Lurgi Furnace since 1972 have been summarized. The problem and developing trend of Lurgi Furnace was alanalyzed and outlooked.%介绍了国内首套自行设计利用劣质褐煤加压气化制氨工艺鲁奇炉运行的状况及出现的问题。总结了自1972年以来,第一代鲁奇炉在运行中存在的主要问题及相应的技术改造状况,并对鲁奇炉运行存在的问题及发展方向进行了分析和展望。

  15. Preconditioning the pressure operator for the time dependent Stokes problem

    Energy Technology Data Exchange (ETDEWEB)

    Bramble, J.H.; Pasciak, J.E.

    1994-12-31

    In implicit time stepping procedures for the linearized Navier Stokes equations, a linear perturbed Stokes problem must be solved at each time step. Many methods for doing this require a good preconditioner for the resulting pressure operator (Schur complement). In contrast to the time independent Stokes equations where the pressure operator is well conditioned, the pressure operator for the perturbed system becomes more illconditioned as the time step is reduced (and/or the Reynolds number is increased). The authors describe the method for solving the coupled velocity/pressure systems and, in particular, show how to construct good preconditioners for the poorly conditioned pressure operator.

  16. Raman spectroscopy under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A F; Crowhurst, J C

    2004-11-05

    We report the results of Raman measurements of various materials under simultaneous conditions of high temperature and high pressure in the diamond anvil cell (DAC). High temperatures are generated by laser heating or internal resistive (ohmic) heating or a combination of both. We present Raman spectra of cubic boron nitride (cBN) to 40 GPa and up to 2300 K that show a continuous pressure and temperature shift of the frequency of the transverse optical mode. We have also obtained high-pressure Raman spectra from a new noble metal nitride, which we synthesized at approximately 50 GPa and 2000 K. We have obtained high-temperature spectra from pure nitrogen to 39 GPa and up to 2000 K, which show the presence of a hot band that has previously been observed in CARS measurements. These measurements have also allowed us to constrain the melting curve and to examine changes in the intramolecular potential with pressure.

  17. Pressure on Yukos growing

    International Nuclear Information System (INIS)

    The fate of the Russian oil concern Yukos seems to be sealed. The former rising star of the Russian energy firmament seems to be dying under the pressure of local state administration. Tax arrears, the fact that the owner Mikhail Khodorkovsky was jailed and the company placed under forced administration reflects the conflict between business and political interests in Russia. And the conflict also has an impact on Slovakia. In the portfolio of Yukos Finance, the Dutch subsidiary of Yukos, are assets that are very attractive for Russian oil concerns. One of them is the Slovak operator of the Druzba pipeline, Transpetrol. Yukos Finance owns 49% of the company's shares. Last year, the company signed a contract with the Russian oil company Russneft on the sale of the stake for 103 mil. USD. According to a contract signed in 2002 that stipulated the conditions under which the Slovak state sold the Transpetrol shares to Yukos for the next 5 years such a step has to be approved by the Ministry of Economy. The Dutch company can also sell the shares without such an approval but then it has to pay a penalty fine. In such a case Slovakia would get 50% of the original amount, i.e. 37 mil. USD. (author)

  18. Barodontalgia.

    Science.gov (United States)

    Zadik, Yehuda

    2009-04-01

    Although considered rare, dentists may encounter oral pain evoked by a change in barometric pressure, a condition known as barodontalgia (aerodontalgia). The article reviews the epidemiology, clinical presentation, pathogenesis, diagnostic process and differential diagnosis (including facial and dental barotrauma) of this phenomenon. Preventive measures are described as well.

  19. ITER Port Interspace Pressure Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Carbajo, Juan J [ORNL; Van Hove, Walter A [ORNL

    2016-01-01

    The ITER Vacuum Vessel (VV) is equipped with 54 access ports. Each of these ports has an opening in the bioshield that communicates with a dedicated port cell. During Tokamak operation, the bioshield opening must be closed with a concrete plug to shield the radiation coming from the plasma. This port plug separates the port cell into a Port Interspace (between VV closure lid and Port Plug) on the inner side and the Port Cell on the outer side. This paper presents calculations of pressures and temperatures in the ITER (Ref. 1) Port Interspace after a double-ended guillotine break (DEGB) of a pipe of the Tokamak Cooling Water System (TCWS) with high temperature water. It is assumed that this DEGB occurs during the worst possible conditions, which are during water baking operation, with water at a temperature of 523 K (250 C) and at a pressure of 4.4 MPa. These conditions are more severe than during normal Tokamak operation, with the water at 398 K (125 C) and 2 MPa. Two computer codes are employed in these calculations: RELAP5-3D Version 4.2.1 (Ref. 2) to calculate the blowdown releases from the pipe break, and MELCOR, Version 1.8.6 (Ref. 3) to calculate the pressures and temperatures in the Port Interspace. A sensitivity study has been performed to optimize some flow areas.

  20. Safe retaining pressures for pressurized tunnel face using nonlinear failure criterion and reliability theory

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-li; YAO Cong; ZHANG Jia-hua

    2016-01-01

    Based on the active failure mechanism and passive failure mechanism for a pressurized tunnel face, the analytical solutions of the minimum collapse pressure and maximum blowout pressure that could maintain the stability of pressurized tunnel faces were deduced using limit analysis in conjunction with nonlinear failure criterion under the condition of pore water pressure. Due to the objective existence of the parameter randomness of soil, the statistical properties of random variables were determined by the maximum entropy principle, and the Monte Carlo method was employed to calculate the failure probability of a pressurized tunnel. The results show that the randomness of soil parameters exerts great influence on the stability of a pressurized tunnel, which indicates that the research should be done on the topic of determination of statistical distribution for geotechnical parameters and the level of variability. For the failure probability of a pressurized tunnel under multiple failure modes, the corresponding safe retaining pressures and optimal range of safe retaining pressures are calculated by introducing allowable failure probability and minimum allowable failure probability. The results can provide practical use in the pressurized tunnel engineering.