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Sample records for barometric pressure conditions

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

    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

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

    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...

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

    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.

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

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

    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

  7. Classification of daily-life postural transitions using trunk-worn wearable barometric pressure sensor

    Massé, Fabien; Bourke, Alan Kevin; Ionescu, Anisoara; Aminian, Kamiar

    2013-01-01

    Distinguishing sedentary from dynamic behavior is essential in addressing disease conditions that are influenced by mobility. Event-based activity recognition algorithms essentially rely on accurate classification of siting and standing postural transitions to distinguish whether the subject is sitting or standing. In this paper, the use of barometric pressure, to estimate altitude, is investigated. It enabled a correct classification of postural transitions with a sensitivity of 92.31% and s...

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

    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

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

    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.

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

    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. PMID:25219097

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

    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...

  12. Activity classification based on inertial and barometric pressure sensors at different anatomical locations

    Miniature, wearable sensor modules are a promising technology to monitor activities of daily living (ADL) over extended periods of time. To assure both user compliance and meaningful results, the selection and placement site of sensors requires careful consideration. We investigated these aspects for the classification of 16 ADL in 6 healthy subjects under laboratory conditions using ReSense, our custom-made inertial measurement unit enhanced with a barometric pressure sensor used to capture activity-related altitude changes. Subjects wore a module on each wrist and ankle, and one on the trunk. Activities comprised whole body movements as well as gross and dextrous upper-limb activities. Wrist-module data outperformed the other locations for the three activity groups. Specifically, overall classification accuracy rates of almost 93% and more than 95% were achieved for the repeated holdout and user-specific validation methods, respectively, for all 16 activities. Including the altitude profile resulted in a considerable improvement of up to 20% in the classification accuracy for stair ascent and descent. The gyroscopes provided no useful information for activity classification under this scheme. The proposed sensor setting could allow for robust long-term activity monitoring with high compliance in different patient populations. (paper)

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

    Yönet, Sinem; Esen, Olgun; Fişne, Abdullah

    2015-04-01

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

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

    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

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

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

    2016-06-01

    Apparent acceleration in 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 (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/yr2, which is large relative to prior GRACE estimates of Antarctic ice mass acceleration in the range of -12 to -14 Gt/yr2. 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/yr2). 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.

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

    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.

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

    Özkil, Ali Gürcan; Fan, Zhun; Xiao, Jizhong; Dawids, Steen; Kristensen, Jens Klæstrup; Christensen, Kim Hardam

    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 i...

  18. Barometric altimetry system as virtual constellation applied in CAPS

    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.

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

    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....

  20. Critical conditions of pressurized pipes

    Gajdoš, Lubomír; Šperl, Martin

    2013-01-01

    Roč. 20, č. 5 (2013), s. 401-412. ISSN 1802-1484 R&D Projects: GA ČR(CZ) GAP105/10/2052 Institutional support: RVO:68378297 Keywords : pressurized pipe * J-integral * C factor * critical conditions Subject RIV: JL - Materials Fatigue, Friction Mechanics http://www.engineeringmechanics.cz/obsahy.html?R=20&C=5

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

    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.

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

    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

  3. Field measurements of tracer gas transport by barometric pumping

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

  4. 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

    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

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

    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…

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

    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.

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

    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

  8. A Stochastic Approach to Noise Modeling for Barometric Altimeters

    Angelo Maria Sabatini; Vincenzo Genovese

    2013-01-01

    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 w...

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

    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

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

    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

  11. Practical conditions in the neutron diffraction under high pressure

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

  12. Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with Gyrotropic Pressure

    Double, Glen P.; Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2003-01-01

    Shock jump conditions are obtained for steady-state, plane shocks with oblique magnetic fields and arbitrary flow speeds. For ultrarelativistic and nonrelativistic shocks, the jump conditions may be solved analytically. For mildly relativistic shocks, analytic solutions are obtained for isotropic pressure using an approximation for the adiabatic index that is valid in high sonic Mach number cases. In the more general case of gyrotropic pressure, the jump conditions cannot be solved analytical...

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

    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

  14. Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with Gyrotropic Pressure

    Double, G P; Jones, F C; Ellison, D C; Double, Glen P.; Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2004-01-01

    Shock jump conditions are obtained for steady-state, plane shocks with oblique magnetic fields and arbitrary flow speeds. For ultrarelativistic and nonrelativistic shocks, the jump conditions may be solved analytically. For mildly relativistic shocks, analytic solutions are obtained for isotropic pressure using an approximation for the adiabatic index that is valid in high sonic Mach number cases. In the more general case of gyrotropic pressure, the jump conditions cannot be solved analytically without additional assumptions, and the effects of gyrotropic pressure are investigated by parameterizing the distribution of pressure parallel and perpendicular to the magnetic field. Our numerical solutions reveal that relatively small departures from isotropy (e.g., about 20%) produce significant changes in the shock compression ratio, r, at all shock Lorentz factors, including ultrarelativistic ones, where an analytic solution with gyrotropic pressure is obtained. In particular, either dynamically important fields ...

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

    Angelo Maria Sabatini

    2014-07-01

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

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

    Qing-song Yan; Huan Yu; Gang Lu

    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 alloys was discussed, and the solidification feeding model under grade-pressuring condition was established. The results indicate the grade-pressured solidification feeding ability of vacuum counter-pressure casting mainly depends on grade pressure difference and time. With the increase of grade pressure di...

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

    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.

  18. Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with Gyrotropic Pressure

    Double, Glen P.; Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2003-01-01

    Shock jump conditions, i.e., the specification of the downstream parameters of the gas in terms of the upstream parameters, are obtained for steady-state, plane shocks with oblique magnetic fields and arbitrary flow speeds. This is done by combining the continuity of particle number flux and the electromagnetic boundary conditions at the shock with the magnetohydrodynamic conservation laws derived from the stress-energy tensor. For ultrarelativistic and nonrelativistic shocks, the jump conditions may be solved analytically. For mildly relativistic shocks, analytic solutions are obtained for isotropic pressure using an approximation for the adiabatic index that is valid in high sonic Mach number cases. Examples assuming isotropic pressure illustrate how the shock compression ratio depends on the shock speed and obliquity. In the more general case of gyrotropic pressure, the jump conditions cannot be solved analytically with- out additional assumptions, and the effects of gyrotropic pressure are investigated by parameterizing the distribution of pressure parallel and perpendicular to the magnetic field. Our numerical solutions reveal that relatively small departures from isotropy (e.g., approximately 20%) produce significant changes in the shock compression ratio, r , at all shock Lorentz factors, including ultrarelativistic ones, where an analytic solution with gyrotropic pressure is obtained. In particular, either dynamically important fields or significant pressure anisotropies can incur marked departures from the canonical gas dynamic value of r = 3 for a shocked ultrarelativistic flow and this may impact models of particle acceleration in gamma-ray bursts and other environments where relativistic shocks are inferred. The jump conditions presented apply directly to test-particle acceleration, and will facilitate future self-consistent numerical modeling of particle acceleration at oblique, relativistic shocks; such models include the modification of the fluid

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

    Mirijam Vrabec

    2010-06-01

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

  20. Investigations on pressure suppression system loads at accident conditions

    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.)

  1. Application of Relationship Between Groundwater Level and Atmospheric Pressure Change

    Kim, S. J.; Lee, K.

    2013-12-01

    Change in atmospheric pressure affects ground water levels. Barometric efficiency, which is an indicator for different exposure to the atmospheric pressure of observation well and adjacent ground cover, can be used as an effective tool for estimating some groundwater properties. If the top of an observation well is sealed and contact with the atmosphere is blocked, there would be no pressure difference between the well and adjacent ground cover. As a result, the difference between barometric efficiency values of sealed and unsealed well of identical condition can indicates the effect of atmospheric pressure changes on the groundwater level. One month observation data of hydraulic head and atmospheric pressure at Wonju-si in Gangwon-do, Korea are used. Two different methods, Clark's method and graphical method, are adopted to estimate the barometric efficiency. Because the efficiency has implication on the properties of aquifer covering condition, mapping of this efficiency might be used for estimating groundwater vulnerability of contamination from surface-loaded sources.

  2. Barometric tides from ECMWF operational analyses

    R. D. Ray

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

    Key words. Meteorology and atmospheric dynamics (waves and tides

  3. Modeling of Spray Combustion under Cryogenic and High Pressure Conditions

    Schlotz, D.; Vogelgesang, M.; E. Gutheil; Clauss, W.; Sender, J

    2005-01-01

    The paper concerns both the numerical and experimental investigation of turbulent liquid oxygen/hydrogen spray combustion for elevated subcritical pressure and cryogenic inlet temperature conditions. In particular, the combustion in the single injector combustion chamber is studied where experimental data are obtained for gas phase temperature and both droplet size and velocities. The model uses an Eulerian--Lagrangian formulation for the gas and the liquid phase, respectively. Detailed ...

  4. A Stochastic Approach to Noise Modeling for Barometric Altimeters

    Angelo Maria Sabatini

    2013-11-01

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

  5. Photoelectron Spectroscopy under Ambient Pressure and Temperature Conditions

    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.

  6. Horizon pressure from junction conditions for Schwarzschild and Rindler geometries

    Culetu, Hristu

    2016-01-01

    We assumed a stress tensor is necessary on the event horizon of a Schwarzschild black hole or on the Rindler horizon for the Israel matching conditions to be satisfied. We found the surface energy density $\\rho_{s}$ is vanishing but the surface pressure $p_{s}$ equals $1/16\\pi l$ in both cases, where $l$ is the proper distance from the horizon. The junction relations are applied both for $r =$ const. and $T =$ const. surfaces, with the same results for the surface parameters $\\rho_{s}$ and $p_{s}$. We emphasize the nonstatic feature of the spacetimes beyond the corresponding horizons.

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

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

  8. Evaluation of pressurized thermal shock in transitional condition for boiling water reactor pressure vessel

    The structural integrity for Pressurized Thermal Shock (PTS) was evaluated for the RPVs of Japanese Boiling Water Reactors (BWRs). It has been clarified that the BWR RPVs have the sufficient margin of fracture toughness by calculating the stress intensity factor in transitional condition and the acceptance criteria for RPV shell plate which is assumed to be neutron-irradiated in core region for 60 years. (author)

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

    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.

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

    Qing-song Yan

    2016-03-01

    Full Text Available 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 alloys was discussed, and the solidification feeding model under grade-pressuring condition was established. The results indicate the grade-pressured solidification 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 all the aluminum alloy 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 wall thicknesses, and the solidification time when the solid volume fraction of aluminum alloy reaches about 0.65 appears to be the optimal beginning time for grade-pressuring.

  11. PRESSURE INTEGRITY OF 3013 CONTAINER UNDER POSTULATED ACCIDENT CONDITIONS

    Rawls, G.

    2010-02-01

    A series of tests was carried out to determine the threshold for deflagration-to-detonation transition (DDT), structural loading, and structural response of the Department of Energy 3013 storage systems for the case of an accidental explosion of evolved gas within the storage containers. Three experimental fixtures were used to examine the various issues and three mixtures consisting of either stoichiometric hydrogen-oxygen, stoichiometric hydrogen-oxygen with added nitrogen, or stoichiometric hydrogen-oxygen with an added nitrogen-helium mixture were tested. Tests were carried out as a function of initial pressure from 1 to 3.5 bar and initial temperature from room temperature to 150 C. The elevated temperature tests resulted in a slight increase in the threshold pressure for DDT. The elevated temperature tests were performed to ensure the test results were bounding. Because the change was not significant the elevated temperature data are not presented in the paper. The explosions were initiated with either a small spark or a hot surface. Based on the results of these tests under the conditions investigated, it can be concluded that DDT of a stoichiometric hydrogen-oxygen mixture (and mixtures diluted with nitrogen and helium) within the 3013 containment system does not pose a threat to the structural integrity of the outer container.

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

    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...

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

    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. Dust acoustic and gravity modes in barometric equilibrium

    This paper deals with mode in nonrotating horizontally stratified dusty atmosphere. We have studied dust gravity and acoustic modes in presence of a barometric equilibrium in an unmagnetized dusty plasma. All the dust grains are considered to have same and fixed negative (positive) charge on them. The electron and ions are considered to obey isothermal equations of state while the dust grain are following an adiabatic equation of state. This work can be considered as a generalization of single fluid treatment of gravity-acoustic modes. The analysis of dispersion relation suggests that the dust grains can introduce a new decay length of the perturbation. Therefore we find that the dispersion characteristics of single fluid treatment is strongly modified in the presence of charged dust grain. Finally we discussed importance of our results in the context of planetary and stellar environments

  15. Bridge Pressure Flow Scour at Clear Water Threshold Condition

    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.

  16. Chlorogenic acid stability in pressurized liquid extraction conditions.

    Wianowska, Dorota; Typek, Rafał; Dawidowicz, Andrzej L

    2015-01-01

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

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

    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.

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

    Ionescu, S. [Institute for Nuclear Research Pitesti, Campului Str., 1, 115400 Mioveni (Romania)], E-mail: silviu.ionescu@nuclear.ro; Uta, O.; Parvan, M.; Ohai, D. [Institute for Nuclear Research Pitesti, Campului Str., 1, 115400 Mioveni (Romania)

    2009-03-31

    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.

  19. AN APPROXIMATION TO LATERAL EARTH PRESSURES FOR K0 CONDITION

    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.

  20. Study of graphite strength properties under conditions of hydrostatic pressure

    Three graphite grades are studied under compression, tension and hydrostaic pressure. It is shown that an increase in the ultimate strength and higher arrangement of strain curves are observed beginning with a certain value of hydrostatic pressure under compression. Several different types of coatings have been tested under compression and none of them gave a reliable protection against of oil in pores and cracks of a specimen as a result of which the strength values in this case are lower that under atmospheric pressure

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

    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...... technology to design and fabricate these sensors has been implemented. Capacitive pressure sensing, on the other hand, is still an open and really promising field. Results Capacitive microsensors were designed and fabricated (Fig. 1) and an analytical model for touch mode regime, which fitted accurately the...... is therefore to develop new technologies based on capacitive sensing to be able to fulfil future requirements in this field....

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

    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.)

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

    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.

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

    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)

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

    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.

  6. Micromachined capacitive pressure sensor with signal conditioning electronics

    Fragiacomo, Giulio

    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....... This demonstrator has been characterized and presented at Grundfos Direct Sensors A/S and constitute the preliminary work for a new product which is intended target the low power or wireless pressure sensor for harsh environment market....

  7. Kinetic study of biomass hydrolysis under high pressure conditions

    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 ...

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

    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

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

    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.)

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

    'The intent of this research program is to obtain an improved understanding of vadose zone transport processes and to develop field and modeling techniques required to characterize contaminant transport in the unsaturated zone at DOE sites. For surface spills and near-surface leaks of chemicals, the vadose zone may well become a long-term source of contamination for the underlying water table. Transport of contaminants can occur in both the liquid and gas phases of the unsaturated zone. This transport occurs naturally as a result of diffusion, buoyancy forces (gravity), capillarity and barometric pressure variations. In some cases transport can be enhanced by anisotropies present in hydrologic regimes. This is particularly true for gas-phase transport which may be subject to vertical pumping resulting from atmospheric pressure changes. For liquid-phase flows, heterogeneity may enhance the downward transport of contaminants to the water table depending on soil properties and the scale of the surface spill or near-surface leak. Characterization techniques based upon the dynamics of transport processes are likely to yield a better understanding of the potential for contaminant transport at a specific site than methods depending solely on hydrologic properties derived from a borehole. Such dynamic-characterization techniques can be useful for evaluating sites where contamination presently exists as well as for providing an objective basis to evaluate the efficacy of proposed as well as implemented clean-up technologies. The real-time monitoring of processes that may occur during clean-up of tank waste and the mobility of contaminants beneath the Hanford storage tanks during sluicing operations is one example of how techniques developed in this effort can be applied to current remediation problems. In the future, such dynamic-characterization methods might also be used as part of the site-characterization process for determining suitable locations of new DOE facilities

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

    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

  12. Unifying Paschen Curve Conditions across Pressure and Gap Distance

    Loveless, Amanda; Garner, Allen; Valfells, Agust

    2015-11-01

    The Paschen curve (PC) predicts the breakdown voltage of a gas by relating it to the product of pressure and gap distance (pd). Recent experiments deviate from the PC for microscale gaps at low pd. A scaling law incorporating field emission-driven breakdown and field enhancement to the macroscale Paschen law yields more accurate predictions for microscale gaps (A. Venkattraman and A. A. Alexeenko, Phys. Plasmas 19, 123515 (2012).). While many studies consider low pd, deviations from the PC also arise at high pd, as demonstrated for gap distances between 0.0508 and 0.254 cm and pressures between 96.5 and 6900 kPa (W. J. Carey, A. J. Wiebe, R. D. Nord, and L. L. Altgilbers, in Proc. IEEE Pulsed Power Conf., 2011, pp. 741-744). High pd values are relevant for ongoing high voltage plasma experiments for food treatment and combustion. We attempt to elucidate the impact of large gap distances (~ 5 cm) and higher pressures (~ 200-300 kPa) on these deviations by connecting recent work at low pd to high pd by assessing scaling laws, analyzing field emission models, and using particle-in-cell codes. Implications on experimental design will be discussed, and the development of a universal Paschen curve will be explored.

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

    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.

  14. On Pressure Boundary Conditions for Steady Flows of Incompressible Fluids with Pressure and Shear Rate Dependent Viscosities

    Lanzendörfer, Martin; Stebel, Jan

    2011-01-01

    Roč. 56, č. 3 (2011), s. 265-285. ISSN 0862-7940 R&D Projects: GA MŠk LC06052 Grant ostatní: GA ČR(CZ) GA201/06/0352 Institutional research plan: CEZ:AV0Z10300504; CEZ:AV0Z10190503 Keywords : existence * weak solutions * incompressible fluids * non - Newtonian fluids * pressure dependent viscosity * shear dependent viscosity * inflow/outflow boundary conditions * pressure boundary conditions * filtration boundary conditions Subject RIV: BK - Fluid Dynamics Impact factor: 0.480, year: 2011 http://dml.cz/handle/10338.dmlcz/141486

  15. On pressure boundary conditions for steady flows of incompressible fluids with pressure and shear rate dependent viscosities

    Lanzendörfer, Martin; Stebel, Jan

    Ostrava: Institute of Geonics AS CR, 2009 - (Blaheta, R.; Starý, J.). s. 71-75 ISBN 978-80-86407-60-9. [SNA '09 - Seminar on numerical analysis: modelling and simulation of challenging engineering problems. 02.02.2009-06.02.2009, Ostrava] R&D Projects: GA MŠk LC06052; GA ČR(CZ) GA201/06/0352 Institutional research plan: CEZ:AV0Z10300504 Keywords : existence * weak solutions * incompressible fluids * non - Newtonian fluids * pressure dependent viscosity * shear dependent viscosity * inflow/outflow boundary conditions * pressure boundary conditions * filtration boundary conditions http://www.ugn.cas.cz/events/2009/sna/sbornik.pdf

  16. Intramuscular pressures for monitoring different tasks and muscle conditions

    Sejersted, O. M.; Hargens, A. R.

    1995-01-01

    Intramuscular fluid pressure (IMP) can easily be measured in man and animals. It follows the law of Laplace which means that it is determined by the tension of the muscle fibers, the recording depth and by fiber geometry (fiber curvature or pennation angle). Thick, bulging muscles create high IMPs (up to 1000 mmHg) and force transmission to tendons becomes inefficient. High resting or postexercise IMPs are indicative of a compartment syndrome due to muscle swelling within a low-compliance osseofascial boundary. IMP increases linearly with force (torque) independent of the mode or speed of contraction (isometric, eccentric, concentric). IMP is also a much better predictor of muscle force than the EMG signal. During prolonged low-force isometric contractions, cyclic variations in IMP are seen. Since IMP influences muscle blood flow through the muscle pump, autoregulating vascular elements, and compression of the intramuscular vasculature, alterations in IMP have important implications for muscle function.

  17. Pressurized water reactor iodine spiking behavior under power transient conditions

    The most accepted theory explaining the cause of pressurized water reactor iodine spiking is steam formation and condensation in damaged fuel rods. The phase transformation of the primary coolant from water to steam and back again is believed to cause the iodine spiking phenomenon. But due to the complex nature of the phenomenon, a comprehensive model of the behavior has not yet been successfully developed. This paper presents a new model based on an empirical approach, which gives a first-order estimation of the peak iodine spiking magnitude. Based on the proposed iodine spiking model, it is apparent that it is feasible to derive a correlation using the plant operating data base to monitor and control the peak iodine spiking magnitude

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

    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)

  19. An alternative method to Mariotte reservoir system for maintaining constant hydraulic pressure

    Some studies being done to evaluate the suitability of the Yucca Mountain area as a potential radioactive waste repository require the application of a constant water pressure as a boundary condition to study water flow through porous media. The Mariotte reservoir system is commonly used to supply such a boundary condition. Several problems with the Mariotte reservoir system were discovered when it was used to apply a constant water pressure as a boundary condition for a prolonged period. The constant-pressure boundary condition is required for some lab. experiments to study water flow through porous media. The observed problems were caused by temperature and barometric-pressure fluctuations while the flow rates were very small and caused erroneous water flow-rate measurements. An alternative method was developed and used where the water pressure is controlled by regulating its level by using water-level sensing electrodes. The new method eliminated the effects of temperature and barometric-pressure fluctuations and maintained an acceptable accuracy of the estimated water flow rate without compromising the advantage of the Mariotte reservoir

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

    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

  1. Cable condition monitoring in a pressurized water reactor environment

    Oconee Nuclear Station is the first nuclear plant designed, engineered and constructed by Duke Power Company. Even though the accelerated aging method was available to determine the life expectancy of the cable used in the reactor building, no natural aging data was available at that time. In order to be able to verify the condition of the reactor building cable over the life of the plant, an on-going cable monitoring plan was instituted. Various types of cable were selected to be monitored, and they were installed in cable life evaluation circuits in the reactor building. At five year intervals over the life of the plant, cable samples would be removed from these cable life evaluation circuits and tested to determine the effects of the reactor building environment on the integrity of the cable. A review of the cable life evaluation circuits and the results of the evaluation program to date is presented

  2. Application of the subchannel analysis code MATRA for low flow and low pressure conditions

    Subchannel analysis codes usually solve a boundary value problem and use a multipass marching scheme. This multi-pass marching scheme finds the enthalpy, density, cross flow, axial flow and pressure at each axial plane until errors of the cross flow and axial flow satisfy convergence criteria and then the scheme iterates an axial sweep until finding unknown inlet boundary conditions that satisfy the outlet boundary conditions. In this approach, numerical errors at each iteration are accumulated and may induce numerical instabilities such as a numerical oscillation or loss of diagonal dominance under low-pressure and low-flow conditions. This paper presents an improvement of a convergence of a subchannel analysis code under low-pressure and low-flow rate conditions. A once-through marching scheme was implemented into the subchannel analysis code MATRA. The scheme obtains converged numerical solutions at each axial plane by marching from the inlet to the outlet only once. Based on the assumption that the pressure distribution is uniform at each axial plane, the lateral pressure difference between subchannels is sufficiently small. The once through marching scheme was validated firstly by comparisons with the multi-pass marching scheme at high-pressure and high flow conditions. And the performance of the once-through marching scheme was assessed for the low flow and low pressure conditions in the CHF experiments carried out at the Winfrith establishment of the UKAEA. (authors)

  3. WWER-1000 core loading characteristic influence on irradiation conditions of surveillance specimens and reactor pressure vessel

    Irradiation conditions of WWER-1000 surveillance specimens and reactor pressure vessel are comparative analyzed for various core loadings. It is proved that the fluences onto specimens don't correlate with ones onto pressure vessel. It is shown that the reconstruction technique using to surveillance specimens of the standard program implemented at the most of the power units with WWER-1000 allows obtaining reliable information on the reactor pressure vessel metal states

  4. Study of intestinal mucosa in high pressure conditions of variable pressure SEM

    Flodrová, Eva; Neděla, Vilém

    Nové Město na Moravě : Československá mikroskopická společnost, 2010 - (Frank, L.; Hozák, P.), s. 33 ISBN N. [Mikroskopie 2010. Nové Město na Moravě (CZ), 17.02.2010-18.02.2010] R&D Projects: GA ČR GAP102/10/1410 Institutional research plan: CEZ:AV0Z20650511 Keywords : intestinal mucosa * variable pressure SEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

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

    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.)

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

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

    2016-01-01

    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. PMID:27322288

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

    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 was......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...

  8. Biogenic amines in pressurized vacuum-packaged cooked sliced ham under different chilled storage conditions.

    Ruiz-Capillas, C; Carballo, J; Jiménez Colmenero, F

    2007-03-01

    This work was undertaken to study how storage conditions (at constant temperatures of 2±1 and 12±1°C and temperature fluctuations at 7±5°C) affect microbial development and the production of biogenic amines in vacuum-packaged cooked sliced ham subjected to high pressure (400MPa/10min/30°C). Initially, the product exhibited low levels of contamination. Microbiological changes during storage depend on the processing (non-pressure and pressure treatment) and the chilled storage conditions. Generally, microbial growth in pressurized samples was similar to that in the non-pressurized samples, although the total viable count and lactic flora were lower and growth was delayed. Processing and storage conditions affected the formation of each amine differently. The most important changes were in tyramine, which formed more quickly in non-pressurized products stored at 12°C and with temperature fluctuations. The formation of biogenic amines in these products can be prevented not only by ensuring good manufacturing practices and applying high pressure but also by ensuring the right chilled storage conditions. PMID:22063795

  9. Deformation behaviour of Zr-2.5 wt percent Nb pressure tubes under internal pressurization and ramp temperature conditions

    The deformation behaviour of 0.6 m long Zr-2.5 wt percent Nb pressure tube specimens deformed under internal pressurization and ramp temperature conditions has been studied. Both inert gas and steam have been used as the pressurizing medium. Controlled heating rates in the range 1-25 K/s and internal pressures in the range 0-12 MPa have been investigated. It was observed that, except at the very high test pressures, the samples deformed to circumferential strains well in excess of the nominal 'contact' strain of 0.18 before possible rupture. Over the time scale of the biaxial tests carried out, the effect of steam on deformation behaviour appeared to be minimal. It was also found that the major features of the biaxial deformation behaviour can be investigated, at least qualitatively, by carrying out uniaxial tensile tests. However, detailed analysis of uniaxial and biaxial data showed that there were several major differences between the two types of data. These differences are discussed in considerable detail in the present report

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

    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.

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

    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...

  12. Snapback testing of the HDR reactor pressure vessel and a primary steam pipe under operating conditions

    A remotely operated snapback excitation system was used for vibration tests under different operating conditions (temperature 20-2850C, internal pressure 0-70 bar). The measured acceleration-, displacement- and strain time histories were analyzed to identify the influence of temperature and internal pressure on the vibration behavior of a real system in its real environment. Additionally, the measurement results were compared with results of pretest calculations of the test load cases. (orig./HP)

  13. Pressure drop across micro-pin heat sinks under boiling conditions

    Koşar, Ali; Kosar, Ali; Özdemir, Mehmed Rafet; Ozdemir, Mehmed Rafet; Keskinöz, Mehmet; Keskinoz, Mehmet

    2009-01-01

    Two-phase pressure drop was studied in four different micro pin fin heat sinks. Micro pin fin heat sinks used in the current studies were operated under boiling conditions using water and R-123 as working fluids. It was observed that once boiling was initiated severe temperature fluctuations and flow oscillations were recorded for three of the micro pin fin heat sinks, which was characterized as unstable boiling. Pressure drop signals were presented just before and after the unstable boili...

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

    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.

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

    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.

  16. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    Sandberg, R. L.; Rodriguez, G.; Gibson, L. L.; Dattelbaum, D. M.; Stevens, G. D.; Grover, M.; Lalone, B. M.; Udd, E.

    2014-05-01

    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

  17. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

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

    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.

  19. Convective Heat Exchange in Downward Moving Liquid under Conditions of Over-Critical Pressures

    G. I. Isaev

    2014-01-01

    The paper presents some results of experimental investigations on convective heat exchange to laminar n-heptane flow under conditions of over-critical pressure. The case has been considered when directions of forced and free motion are mutually opposite.Under condition tc ≥ tm some specific heat exchange modes being peculiar for the area of over-critical pressure have been determined.On the basis of experimental data on n-heptane heat exchange recommendations for the evaluation of heat exchan...

  20. Gene Profiling of Aortic Valve Interstitial Cells under Elevated Pressure Conditions: Modulation of Inflammatory Gene Networks

    James N. Warnock

    2011-01-01

    Full Text Available The study aimed to identify mechanosensitive pathways and gene networks that are stimulated by elevated cyclic pressure in aortic valve interstitial cells (VICs and lead to detrimental tissue remodeling and/or pathogenesis. Porcine aortic valve leaflets were exposed to cyclic pressures of 80 or 120 mmHg, corresponding to diastolic transvalvular pressure in normal and hypertensive conditions, respectively. Linear, two-cycle amplification of total RNA, followed by microarray was performed for transcriptome analysis (with qRT-PCR validation. A combination of systems biology modeling and pathway analysis identified novel genes and molecular mechanisms underlying the biological response of VICs to elevated pressure. 56 gene transcripts related to inflammatory response mechanisms were differentially expressed. TNF-α, IL-1α, and IL-1β were key cytokines identified from the gene network model. Also of interest was the discovery that pentraxin 3 (PTX3 was significantly upregulated under elevated pressure conditions (41-fold change. In conclusion, a gene network model showing differentially expressed inflammatory genes and their interactions in VICs exposed to elevated pressure has been developed. This system overview has detected key molecules that could be targeted for pharmacotherapy of aortic stenosis in hypertensive patients.

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

    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.

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

    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 ...

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

    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...

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

    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.

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

    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.

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

    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)

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

    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

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

    V. B. Tawakley

    1960-10-01

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

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

    Duggen, Lars; Lopes, Natasha; Willatzen, Morten; Rubahn, Horst-Günter

    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...

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

    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.

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

    Liu, Nai-Chieh; David R Sargan; Adams, Vicki J; Ladlow, Jane F.

    2015-01-01

    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 bulldog...

  12. Experimental study of the pressure fluctuations on propeller turbine runner blades: part 2, transient conditions

    Houde, S.; Fraser, R.; Ciocan, G.; Deschênes, C.

    2012-11-01

    Transient conditions such as load rejection will often lead to high amplitude pressure fluctuations that will affect a turbine residual-life. If Computational Fluid Dynamic offers a promising tool to study the flow dynamic under transient regime, focused validation data on the runner are still lacking to assess the accuracy of different simulation strategies. Hence within the framework of the AxialT project of the International Consortium on Hydraulic Machines, exploratory measurements of the pressure field on the runner blades of a propeller turbine model were performed in transient conditions. The model was setup on the test stand of the LAMH of Laval University. The test stand control procedures were adapted to mimic transient condition such as load rejection or the transition from a normal operating condition to a speed-no-load condition. The pressure on the runner blades were measured using miniature piezo-resistive transducer linked to a high frequency telemetric system. Using specifically adapted data processing routines, it was possible to characterize the variations of the energy content during the transient runs. Specifically, the main fluctuations appear to occur in the sub-synchronous range in both cases.

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

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

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

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

    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.

  16. Safety conditions of using structural steels under high temperature and pressures in hydrogen containing environment

    The method for establishing full-strength conditions was suggested on the base of results of creep-rupture test of tube samples under hydrogen pressure and according to permissible stresses in neutral medium. Applicability of the method was considered taking St3 and 12KhM steels as examples. It was shown that the use of suggested dependences and special efficiency factors enables to forecast endurance limit for the given steel grade and assigned partial hydrogen pressure without labour-intensive test conducting

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

    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

  18. Effect of sporulation conditions on the resistance of Bacillus subtilis spores to heat and high pressure.

    Nguyen Thi Minh, Hue; Durand, Alain; Loison, Pauline; Perrier-Cornet, Jean-Marie; Gervais, Patrick

    2011-05-01

    Bacillus subtilis(B. subtilis) cells were placed in various environmental conditions to study the effects of aeration, water activity of the medium, temperature, pH, and calcium content on spore formation and the resulting properties. Modification of the sporulation conditions lengthened the growth period of B. subtilis and its sporulation. In some cases, it reduced the final spore concentration. The sporulation conditions significantly affected the spore properties, including germination capacity and resistance to heat treatment in water (30 min at 97°C) or to high pressure (60 min at 350 MPa and 40°C). The relationship between the modifications of these spore properties and the change in the spore structure induced by different sporulation conditions is also considered. According to this study, sporulation conditions must be carefully taken into account during settling sterilization processes applied in the food industry. PMID:21380515

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

    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.

  20. Local conditions separating expansion from collapse in spherically symmetric models with anisotropic pressures

    Mimoso, José P.; Le Delliou, Morgan; Mena, Filipe C.

    2013-08-01

    We investigate spherically symmetric spacetimes with an anisotropic fluid and discuss the existence and stability of a separating shell dividing expanding and collapsing regions. We resort to a 3+1 splitting and obtain gauge invariant conditions relating intrinsic spacetime quantities to properties of the matter source. We find that the separating shell is defined by a generalization of the Tolman-Oppenheimer-Volkoff equilibrium condition. The latter establishes a balance between the pressure gradients, both isotropic and anisotropic, and the strength of the fields induced by the Misner-Sharp mass inside the separating shell and by the pressure fluxes. This defines a local equilibrium condition, but conveys also a nonlocal character given the definition of the Misner-Sharp mass. By the same token, it is also a generalized thermodynamical equation of state as usually interpreted for the perfect fluid case, which now has the novel feature of involving both the isotropic and the anisotropic stresses. We have cast the governing equations in terms of local, gauge invariant quantities that are revealing of the role played by the anisotropic pressures and inhomogeneous electric part of the Weyl tensor. We analyze a particular solution with dust and radiation that provides an illustration of our conditions. In addition, our gauge invariant formalism not only encompasses the cracking process from Herrera and co-workers but also reveals transparently the interplay and importance of the shear and of the anisotropic stresses.

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

    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.

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

    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.

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

    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

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

    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.

  5. Tear film dynamics on an eye-shaped domain I: pressure boundary conditions.

    Maki, Kara L; Braun, Richard J; Henshaw, William D; King-Smith, P Ewen

    2010-09-01

    We study the relaxation of a model for the human tear film after a blink on a stationary eye-shaped domain corresponding to a fully open eye using lubrication theory and explore the effects of viscosity, surface tension, gravity and boundary conditions that specify the pressure. The governing non-linear partial differential equation is solved on an overset grid by a method of lines using a finite-difference discretization in space and an adaptive second-order backward-difference formula solver in time. Our 2D simulations are calculated in the Overture computational framework. The computed flows show sensitivity to both our choices between two different pressure boundary conditions and the presence of gravity; this is particularly true around the boundary. The simulations recover features seen in 1D simulations and capture some experimental observations including hydraulic connectivity around the lid margins. PMID:20064825

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

    Zhao, Pengfei; Roy, Subrata, E-mail: roy@ufl.edu [Applied Physics Research Group, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-05-07

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

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

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

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

    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

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

    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.

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

    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

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

    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...

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

    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%.

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

    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.

  14. The Influence of Collar on Surge Pressure Caused by the Drill String Inertia Force Under Closed Pipe Condition

    Jun Li; Shengyu Bi; Jun Zou; Gonghui Liu

    2013-01-01

    The study of surge pressure is of significant importance for the safety of drilling process. However, the existing surge pressure models rarely take the impact of the collar into consideration and thus will inevitably affect the precision of the surge pressure calculation. In this paper, based on closed pipe condition, a steady-state calculation model for surge pressure caused by drill string inertia force is developed considering the presence of collar. In the end a case study is presented t...

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

    Highlights: ► Circumferential temperature gradient for asymmetric heat-up was 400 °C. ► At same pressure ballooning initiates at lower temperature in asymmetrical heat-up. ► At 1 MPa ballooning initiated at 408 °C and with expansion rate of 0.005 mm/s. ► At 2 MPa ballooning initiation at 330 °C and with expansion rate of 0.0056 mm/s. ► 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 °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 maintained under both loading conditions. Heat sink around of test section, simulating moderator is found to be helpful in arresting the rise in temperature for both fuel

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

    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

  17. Coordinated vehicle traction control based on engine torque and brake pressure under complicated road conditions

    Kang, Mingxin; Li, Liang; Li, Hongzhi; Song, Jian; Han, Zongqi

    2012-09-01

    Vehicle traction control system has been developed to enhance the traction capability and the direction stability of the driving wheels through the tyre slip ratio regulation. Under normal situations, if the tyre slip ratio exceeds a certain threshold, the slip ratio of the driving wheel is regulated by the coupled interaction of the engine torque and the active brake pressure. In order to obtain the best driving performance on a road under complicated friction conditions, the driving torque and the active brake pressure, need to be decoupled and adjusted to avoid penalisation of each other. In this paper, a coordinated cascade control method with two sliding-mode variable structure controllers is presented. In this control method, the driving wheel slip ratio is regulated by adjusting the engine torque and the wheel brake pressure. Through the sliding-mode controller, the engine torque is tuned to achieve the maximum driving acceleration and then the active brake pressure is applied to the slipped wheel for further modification of the wheel slip ratio. The advantage of this control method is that through proper regulation, the conflict between the two control inputs could be avoided. Finally, the simulation results validate the effectiveness of the proposed method.

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

    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.

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

    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

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

    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)

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

    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)

  2. Glow Discharge Plasma Active Control of Separation at Low Pressure Turbine Conditions.

    Hultgren, Lennart S.; Ashpis, David E.

    2002-11-01

    Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. The base flow includes closed separation bubbles and non-reattaching separated flow, and is thoroughly documented using single-wire constant-temperature anemometry and static surface pressure measurements. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the controlled flow are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.

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

    Habib, Tufail

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

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

    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.

  5. Analysis of Reactor Pressurized Thermal Shock Conditions Considering Upgrading of Systems Important to Safety

    The paper analyzes conditions of pressurized thermal shock on the reactor pressure vessel taking into account upgrading of the emergency core cooling system and primary overpressure protection system. For representative accident scenarios, calculation and comparative analysis was carried out. These scenarios include a small leak from the hot leg and PRZ SV stuck opening with re closure after 3600 sec and 3 SG heat transfer tube rupture. The efficiency of mass flow control by valves on the pump head (emergency core cooling systems) and cold overpressure protection (primary overpressure protection system) was analyzed. The thermal hydraulic model for RELAP5/Mod3.2 code with detailed downcomer (DC) model and changes in accordance with upgrades was used for calculations. Detailed (realistic) modeling of piping and equipment was performed. The upgrades prevent excessive primary cooling and, consequently, help to preserve the RPV integrity and to avoid the formation of a through crack, which can lead to a severe accident

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

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

    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).

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

    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)

  9. 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

    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)

  10. 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

    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)

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

    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

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

    Kuelaots, I.; Yrjas, P.; Hupa, M.; Ots, A.

    1995-09-01

    One of the main problems in conventional combustion boilers firing pulverized oil shale is the corrosion and fouling of heating surfaces, which is caused by sulphur compounds. Another major problem, from the environmental point of view, are the high SO{sub 2} emissions. Consequently, the amount of sulphur in flue gases must be reduced. One alternative to lower the SO{sub 2}, concentration is the use of new technologies, such as pressurized fluidized bed combustion (PFBC). In FBC processes, the sulphur components are usually removed by the addition of limestone (CaCO{sub 3}) or dolomite (CaCO{sub 3} x MgCO{sub 3}) into the bed. The calcium in these absorbents react with SO{sub 2}, producing solid CaSO{sub 4}. However, when burning oil shale, there would be no need to add limestone or dolomite into the bed, due to the initially high limestone content in the fuel (molar ratio Ca/S =10). The capture of sulphur by oil shale ashes has been studied using a pressurized thermogravimetric apparatus (PTGA). The chosen experimental conditions were typical for atmospheric and pressurized fluidized bed combustion. Four different materials were tested - one cyclone ash from an Estonian oil shale boiler, two size fractions of Estonian oil shale and, one fraction of Israeli oil shale. The cyclone ash was found to be the poorest sulphur absorbent. In general, the results from the sulphur capture experiments under both atmospheric and pressurized fluidized bed conditions showed that the oil shale can capture not only its own sulphur but also significant amounts of additional sulphur from another fuel if the fuels are mixed together. (author)

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

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

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

    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...

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

    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

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

    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

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

    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.

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

    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.

  19. Study on intermittent flow behavior in a vertical channel under low-pressure condition

    The intermittent flow behavior in a vertical annulus under a low-pressure condition was experimentally studied using a scaling experiment facility. The temperature and pressure variations in the channel had been obtained under the heat load ranging from 0 to 2.0 kW, initial subcooled water temperature ranging from 50 to 90°C and length–diameter ratio ranging from 1.6 to 50. The effects of the heat load and length–diameter ratio of channel on the flow characteristics were investigated in detail. The experimental results showed that the steam bubbles erupted more frequently and regularly at a high heat load. The intermittent flow period decreased with increase of the heat load and aspect ratio. Based on the mechanism analysis, an empirical model considering the steam oscillation and the vapor–liquid interface rupture based on the experimental data was proposed. It was found that the accumulated steam basically increased linearly. The oscillation of the pressure and velocity decreased gradually with continuous steam accumulation. The Reynolds number of the liquid within the rising section was very small at the stagnation state since there was no forced circulation flow. Finally, a blockage was engendered in the pipeline with the steam accumulated. (author)

  20. The Influence of Collar on Surge Pressure Caused by the Drill String Inertia Force Under Closed Pipe Condition

    Jun Li

    2013-04-01

    Full Text Available The study of surge pressure is of significant importance for the safety of drilling process. However, the existing surge pressure models rarely take the impact of the collar into consideration and thus will inevitably affect the precision of the surge pressure calculation. In this paper, based on closed pipe condition, a steady-state calculation model for surge pressure caused by drill string inertia force is developed considering the presence of collar. In the end a case study is presented to demonstrate the importance of collar during the calculation of surge pressure.

  1. The relation between intraocular pressure change and plasma natriuretic peptide under simulated hypobaric conditions

    Karadag Remzi

    2010-01-01

    Full Text Available Purpose: To ascertain whether the changes in intraocular pressure (IOP that occur during hypobaric hypoxic exposure are related to plasma N-terminal pro-brain natriuretic peptide (BNP levels. Materials and Methods: The study group comprised 26 healthy participants (all male, mean age 23.1 years. IOP was measured at local ground level, (792 m above sea level, then while in a chamber providing hypobaric hypoxic conditions (the subjects were exposed to a pressure equivalent to 9144 m for 1-3 min, and again after exit from the chamber. In each condition, the mean of three consecutive measurements of IOP was calculated for each eye. For BNP measurements, blood samples were drawn before the participants entered the chamber and just after they left the chamber. Results: IOP during hypobaric hypoxic exposure (18.00 ± 3.70 mmHg was significantly greater than that before (15.66 ± 2.10 mmHg, P < 0.001 or after (16.10 ± 2.63 mmHg, P = 0.001 the exposure. IOP levels before and after the exposure were not significantly different (P = 0.136. Plasma BNP levels measured before and after exposure to hypobaric hypoxic conditions were not significantly different (P = 0.462. Conclusion: Plasma BNP levels did not change after short-term hypobaric hypoxic exposure, while the IOP increased. This increase may have been caused by some other systemic factors. As the hypobaric hypoxic conditions were reversed, IOP decreased to normal levels.

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

    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.

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

    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

  4. The impact of inspiratory pressure on stroke volume variation and the evaluation of indexing stroke volume variation to inspiratory pressure under various preload conditions in experimental animals

    Kawazoe, Yu; Nakashima, Tsuyoshi; Iseri, Toshie; Yonetani, Chiaki; Ueda, Kentaro; Fujimoto, Yuka; Kato, Seiya

    2015-01-01

    Purpose Stroke volume variation (SVV) measures fluid responsiveness, enabling optimal fluid management under positive pressure ventilation. We aimed to investigate the effect of peak inspiratory pressure (PIP) on SVV under various preload conditions in experimental animals and to ascertain whether SVV indexed to PIP decreases the effect. Methods Mild and moderate hemorrhage models were created in nine anesthetized, mechanically ventilated beagle dogs by sequentially removing 10 and then an ad...

  5. The Influence of Collar on Surge Pressure Caused by the Drilling Fluid Viscous Force under Pumping Condition

    Jun Li

    2013-02-01

    Full Text Available The study of surge pressure is of significant importance for the safety of drilling process because field practice shows that the surge pressure caused by fluid viscous force can cause a great damage to the drilling operation. The accurate calculation of surge pressure is directly related to the safety of the drilling process. However, the existing surge pressure models rarely take the impact of the collar into consideration and thus will inevitably affect the precision of the surge pressure calculation. In this study, based on the pumping condition, a steady-state calculation model for surge pressure caused by drilling fluid viscous force is developed considering the presence of collar. In the end a case study is presented to demonstrate the importance of collar during the calculation of surge pressure.

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

    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...

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

    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 philoxer...

  8. Case Study for the Numerical Instabilities of the MATRA at Low Flow and Low Pressure Conditions

    Seo, Kyong-Won; Hwang, Dae-Hyun; Song, Jae-Seung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-05-15

    Subchannel analysis codes are very useful and have important roles in analyzing the thermal performance of nuclear reactors. The COBRA and its descendants, including the MATRA, have been widely used as a subchannel analysis code. These codes are known to be unstable for certain conditions. There have been many efforts to resolve unstableness and increase the stability of the subchannel analysis codes. Cuta et al. assessed the stabilities of subchannel analysis codes, VIPRE-01, COBRA-3C, COBRA-IV-I, and LYNX-T with five different experimental data. They found that those codes are unstable for certain cases in a steady state. And they suggested that the cause of unstableness of those codes is the way the lateral pressure difference is updated in the momentum equation. They introduced the crossflow parameter as a measure of the relative numerical stability.

  9. Case Study for the Numerical Instabilities of the MATRA at Low Flow and Low Pressure Conditions

    Subchannel analysis codes are very useful and have important roles in analyzing the thermal performance of nuclear reactors. The COBRA and its descendants, including the MATRA, have been widely used as a subchannel analysis code. These codes are known to be unstable for certain conditions. There have been many efforts to resolve unstableness and increase the stability of the subchannel analysis codes. Cuta et al. assessed the stabilities of subchannel analysis codes, VIPRE-01, COBRA-3C, COBRA-IV-I, and LYNX-T with five different experimental data. They found that those codes are unstable for certain cases in a steady state. And they suggested that the cause of unstableness of those codes is the way the lateral pressure difference is updated in the momentum equation. They introduced the crossflow parameter as a measure of the relative numerical stability

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

    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.

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

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

    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 ...

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

    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

    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

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

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

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

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

    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

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

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

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

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

    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

  2. The kinetics of dolomite reaction rim growth under isostatic and non-isostatic pressure conditions

    Helpa, V.; Rybacki, E.; Morales, L. G.; Abart, R.; Dresen, G. H.

    2013-12-01

    During burial and exhumation, rocks are simultaneously exposed to metamorphic reactions and tectonic stresses. Therefore, the reaction rate of newly formed minerals may depend on chemical and mechanical driving forces. Here, we investigate the reaction kinetics of dolomite (CaMg[CO3]2) rim growth by solid-state reactions experiments on oriented calcite (CaCO3) and magnesite (MgCO3) single crystals under isostatic and non-isostatic pressure conditions. Cylindrical samples of 3-5 mm length and 7 mm diameter were drilled and polished perpendicular to the rhombohedral cleavage planes of natural clear crystals. The tests were performed using a Paterson-type deformation apparatus at P = 400 MPa confining pressure, temperatures, T, between 750 and 850°C, and reaction durations, t, of 2 - 146 h to calculate the kinetic parameters of dolomite rim growth under isostatic stress conditions. For non-isostatic reaction experiments we applied in addition differential stresses, σ, up to 40 MPa perpendicular to the contact interface at T = 750°C for 4 - 171 h duration, initiating minor inelastic deformation of calcite. The thickness of the resulting dolomite reaction rims increases linearly with the square root of time, indicating a diffusion-controlled reaction. The rims consist of two different textural domains. Granular dolomite grains (≈ 2 -5 μm grain size) form next to calcite and elongated palisade-shaped grains (1-6 μm diameter) grow perpendicular to the magnesite interface. Texture measurements with the electron backscatter diffraction technique indicate that the orientations of dolomite grains are mainly influenced by the orientation of the calcite educt crystal, in particular in the granular rim. To some extent, the texture of dolomite palisades is also influenced by the orientation of magnesite. The thickness of the two individual layers increases with temperature. At 400 MPa isostatic pressure, T = 750°C and t = 29 hours, a 5 μm thick granular dolomite layer

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

    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

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

    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

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

    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.

  6. An experimental study on sub-cooled flow boiling CHF of R134a at low pressure condition with atmospheric pressure (AP) plasma assisted surface modification

    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.

  7. AISI 316L under electron radiolysis at high temperature and pressure in PWR modelling conditions

    temperature (HT), 280-320 deg. C, and high pressure (HP), 15.5 MPa. Very few data are available in the literature on the role of HTHP water radiolysis on the corrosion of metallic reactor components. The present approach use electron beam to control the production of radiolytic species at a AISI 316L/PWR solution interface in a high temperature and high pressure (HTHP) electrochemical cell working at the range [25 deg. C, 1 bar] - [300 deg. C, 90 bar]. The cell is designed to record the free corrosion potential of the AISI 316L/PWR solution interface mounted on line at the SIRIUS pelletron delivering the electron beam (LSI, Ecole Polytechnique, France). The PWR primary solutions are simulated by aqueous solutions prepared at room temperature by adding boric acid and lithium hydroxide to high purity water and, in some cases, purged with Ar/H2 flow. At the AISI 316L/PWR solution interfaces irradiated between 25 deg. C/ 1 bar and 300 deg. C/ 90 bar, electrons emerge at ∼0.6 MeV and the flux varies from ∼1010 to 1012 e-.cm-2.s-1. The results clearly show that the response of the free potential between the AISI316L/water interface and a pseudo-reference electrode, i.e. a platinum wire during the irradiation (from electron beam switch-on until cut-off) depends on many parameters: the energy of the electron beam, the temperature and pressure, the concentration of hydrogen in the solution, the ageing of the disc electrode, the growth conditions of the initial oxide passive layers, etc... These results can be compared with those which have obtained by using the proton beam (CEMHTI, CNRS Orleans, France). Surface characterization experiments (XPS, SEM, Raman spectroscopy, photoluminescence...) on the oxide layer of AISI316L which are formed under the irradiation could also bring new information about the irradiation influence on the AISI316L. (authors)

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

    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)

  9. Two-Phase Instability Characteristics of Printed Circuit Steam Generator for the Low Pressure Condition

    Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall manufacturing cost for the components. A PCHE(Printed Circuit Heat Exchanger) is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. PCSG(Printed Circuit Steam Generator) is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. For the introduction of new steam generator, design requirement for the two-phase flow instability should be considered. This paper describes two-phase flow instability characteristics of PCSG for the low pressure condition. PCSG is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. Interconnecting flow path was developed to mitigate the two-phase flow instability in the cold side. The flow characteristics of two-phase flow instability at the PCSG is examined experimentally in this study

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

    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)

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

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

    2002-01-01

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

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

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

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

    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.

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

    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.

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

    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

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

    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.

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

    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)

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

    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.)

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

    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

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

    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...

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

    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.

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

    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...

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

    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

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

    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...

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

    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.

  6. Counter-pressure-assisted ITP with electrokinetic injection under field-amplified conditions for bacterial analysis.

    Phung, Sui Ching; Nai, Yi Heng; Macka, Mirek; Powell, Shane M; Guijt, Rosanne M; Breadmore, Michael C

    2015-09-01

    Counter-pressure was used to extend the duration of field-amplified sample injection in isotachophoresis (FASI-ITP) in order to improve the detection of bacterial cells. Using 0.51-μm negatively charged encapsulated fluorescent beads as a model, the counter-pressure, injection and separation voltages, and times were optimized. Using 6-min 8,963-Pa counter-pressure FASI-ITP injections at -12 kV followed by mobilization of the ITP band with continued injection at -6 kV, the limit of detection (LOD) for Escherichia coli was improved to 78 cells/mL, a factor of 4 when compared with FASI-ITP without counter-pressure. PMID:26143061

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

    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...

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

    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.

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

    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.

  10. Pressure-induced phase transformations in mineral chalcocite, Cu2S, under hydrostatic conditions

    Highlights: • Three previously unknown phase transitions have been found in Cu2S. • 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 Cu2S nanowires. - Abstract: High-pressure room-temperature angle-dispersive powder X-ray diffraction measurements on Cu2S 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 Cu2S nanowires

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

    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

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

    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

  13. Effect of Normal Operating Condition Analysis Method for Weld Residual Stress of CD-ROM Nozzle in Reactor Pressure Vessel

    In pressurized water nuclear reactors (PWRs), the reactor pressure vessel (RSV) upper head contains penetration nozzles that use a control rod drive mechanism (CD-ROM). The penetration nozzle uses J-groove weld geometry. Recently, the occurrence of cracking in alloy 600 CD-ROM penetration nozzle has increased. This is attributable to primary water stress corrosion cracking (PWSCC). PWSCC is known to be susceptible to the welding residual stress and operational stress. Generally, the tensile residual stress is the main factor contributing to crack growth. Therefore, this study investigates the effect on weld residual stress through different analysis methods for normal operating conditions using finite element analysis. In addition, this study also considers the effect of repeated normal operating condition cycles on the weld residual stress. Based on the analysis result, this paper presents a normal operating condition analysis method

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

    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

  15. Liquid gallium in confined droplets under high-temperature and high-pressure conditions

    Phase transitions and the local structure of micrometric droplets of liquid gallium under pressure were studied by combining extended x-ray absorption fine structure, single-energy x-ray absorption detection (SEXAD), and energy-scanning x-ray diffraction (ESXD). Measurements were performed in a range of pressures and temperatures of 0-6.7 GPa and 298-440 K, respectively. The samples for the high-pressure measurements were obtained by using an emulsion of gallium into epoxy resin, a procedure previously developed by the authors. The distribution of droplets was fully characterized by scanning electron microscopy. We found that the liquid can be kept in a metastable state well beyond the liquid-solid coexistence line (1.9 GPa at 300 K). Considering both the ESXD patterns and the SEXAD scans, we infer that the quantity of crystallized gallium droplets increases as a function of pressure, while no sign of crystallization is observed up to 2.7 GPa. The structural and crystallization properties of Ga emulsions, including the determination of the short-range radial distribution function, were measured by XAS in an extended range of pressures and temperatures, putting to a test the possible existence of different Ga-liquid polymorphs

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

    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.

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

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

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

    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...

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

    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.

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

    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...

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

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

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer The water uptake by Eurobitum is studied to judge the safety of geological disposal. Black-Right-Pointing-Pointer High pressures of up to 20 MPa are measured in constant volume water uptake tests. Black-Right-Pointing-Pointer The morphology of leached Eurobitum samples is studied with {mu}CT and ESEM. Black-Right-Pointing-Pointer The observations are reproduced by an existing CHM formulation for Eurobitum. - Abstract: The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at Belgian Nuclear Research Center SCK-CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluna, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO{sub 3} leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography ({mu}CT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to

  2. Effectiveness of Sealed Double-Ring Infiltrometers trademark and effects of changes in atmospheric pressure on hydraulic conductivity

    The Savannah River Site is currently evaluating some 40 hazardous and radioactive-waste sites for remediation. Among the remedial alternatives considered is closure using a kaolin clay cap. The hydraulic conductivity suggested by the US Environmental Protection Agency is 1.0 x 10-7 cm/sec. One instrument to measure this value is the Sealed Double-Ring Infiltrometer trademark (SDRI). Six SDRI were recently installed on a kaolin test cap. Test results demonstrated uniform performance of these instruments. However, the test data showed as much as an order of magnitude of variation over time. This variation is attributed to both internal structural heterogeneity and variable external boundary conditions. The internal heterogeneity is caused by construction variability within a specified range of moisture and density. The external influences considered are temperature and barometric pressure. Temperature was discharged as a source of heterogeneity because of a lack of correlation with test data and a negligible impact from the range of variability. However, a direct correlation was found between changes in barometric pressure and hydraulic conductivity. This correlation is most pronounced when pressure changes occur over a short period of time. Additionally, this correlation is related to a single soil layer. When the wetting front passes into a more porous foundation layer, the correlation with pressure changes disappears. Conclusions are that the SDRI performs adequately, with good repeatability of results. The duration of test is critical to assure a statistically valid data set. Data spikes resulting from pressure changes should be identified, and professional judgment used to determine the representative hydraulic conductivity. Further evaluation is recommended to determine the impact of pressure change on the actual hydraulic conductivity

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

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    the outlet temperature of the gas cooler, the evaporation temperature and the efficiency of the compressor. General correlations for this optimal heat rejection pressure were derived based on cycle simulations. The correlations presented in this paper provide a basis for designing transcritical carbon...

  4. CO2/water interfacial tensions under pressure and temperature conditions of CO2 geological storage

    CO2 storage in aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing CO2 atmospheric concentration. However, its implementation in a given reservoir requires demonstration that CO2 leakage through the reservoir seal (caprock) is extremely limited. One possible cause of rapid leakage is capillary failure of the caprock, which is to a large extent controlled by the CO2/water interfacial tension (IFT). This paper presents pendant drop measurements of IFTs between water and CO2 in a range of temperatures (308-383 K) and pressures (5-45 MPa) relevant to CO2 storage in deep geological formations. Phase densities were measured simultaneously, allowing precise IFT determinations. Increasing the pressure along a given isotherm, IFTs were observed to decrease sharply, then to level off and reach, for pressures above 20 MPa, a pseudo-plateau that decreases slightly with temperature, from around 30 mN/m at 308 K to 23 mN/m at 383 K. The presence of salt (20 g/l NaCl) in the water phase has a negligible effect on the IFT. An important conclusion for CO2 storage is that CO2/brine IFTs have low but reasonable values (higher than 20 mN/m) even at the highest pressures and temperatures examined, and that, neglecting all other possible effects, CO2 storage can, therefore, be considered even in deep geological formations

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

    Liu, Nai-Chieh; Sargan, David R; Adams, Vicki J; Ladlow, Jane F

    2015-01-01

    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 possibly to

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

    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

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

    Mariën, A.; Mokni, N.; Valcke, E.; Olivella, S.; Smets, S.; Li, X.

    2013-01-01

    The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at the Belgian Nuclear Research Center SCK•CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluña, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO3 leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography (μCT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to values that can be (in theory) as high as 42.8 MPa, being the osmotic pressure of a saturated NaNO3 solution. After about four years of hydration in nearly constant volume water uptake tests, pressures up to 20 MPa are measured. During this hydration period only the outer layers with a thickness of 1-2 mm were hydrated (as derived from μCT and ESEM analyses), and only about 10-20% of the initial NaNO3 content was released by the samples. In the studied test

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

    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

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

    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)

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

    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.

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

    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.

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

    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.

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

    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

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

    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)

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

    Rafal Marcin Laskowski

    2011-01-01

    Abstract The study presents the possibility of applying the Buckingham theorem to modeling high-pressure regenerative heat exchangers in changed conditions. A list of independent parameters on which the water temperature at the outlet of the heat exchanger depends was selected; and by means of the Buckingham theorem a functional relation between two dimensionless quantities, where there is no overall heat transfer coefficient, was obtained. The exact form of the function was determined on the...

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

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

  17. Stresses in heated pressurized multi-layer cylinders in generalized plane strain conditions

    An analytical solution for the displacement field and corresponding stress state in multi-layer cylinders subjected to pressure and thermal loading is developed. Solutions are developed for axially loaded and spring-mounted cylinders, assuming that the combined multi-layer cross-section remains plane after deformation (generalized plane strain). The analytical solutions are verified by means of detailed three-dimensional finite element analyses. The solutions are easily implemented in, and suitable for, engineering applications. - Highlights: • An analytical solution for heated pressurized multi-layer cylinders is developed. • The solution is easily implemented and computationally efficient. • The solution highlights application to coated pipelines. • The analytical solution is verified numerically by finite element analyses

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

    Keller, Sandra; Rajasekaran, Priyadarshini; Bibinov, Nikita; Awakowicz, Peter

    2011-01-01

    The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each...

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

    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.

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

    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)

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

    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.

  2. Border control! Capillary pressure / saturation relationships in a diphasic flow in a random medium: Influence of the boundary conditions

    Fiorentino, Eve-Agnès; Toussaint, Renaud; Moura, Marcel; Jankov, Mihailo; Schäfer, Gerhard; Jørgen Måløy, Knut

    2013-04-01

    Solving problems involving biphasic flows in porous media, at a scale larger than the pore one, normally requires the use of relationships between pressure and saturation. These allow the closure of generalized Darcy flow models for two phases, commonly used in hydrology or large scale problems of diphasic flow in porous media. There are mathematical models which approximate experimental records with curve-fitting equations. The two most common models are the Brooks-Corey and van Genüchten ones, they are used to complete a system of generalized Darcy equations. The purpose of the current study is the influence of the boundary conditions on the relationship between pressure and saturation. We perform numerical simulations of drainage experiments. Water is the wetting fluid and air is the non wetting fluid. The results highlight the fact that a filter which allows only water to flow at the exit face of the system modifies both the shape of the curve and the value of the residual saturation. The pressure of the models that are commonly used does not match with the pressure of real flows since there is no filter to cross, to flow from an elementary volume to another. Experiments performed in transparent Hele-Shaw cells exhibit the same features, showing the influence of the semi permeable boundary conditions on the pressure-saturation measures obtained. This effect corresponding to the formation of localized plugging clusters at the boundaries, is obtained in slow flow conditions, and is independent of any dynamic fingering, also known to affect such relations (1,2,3). Modeling flows in open media thus would require to use the central part of the curves pressure saturation where the effect of the boundaries is the least important, or to modify properly these relationships to extract the behavior unaffected by boundaries. References: (1) Two-phase flow: structure, upscaling, and consequences for macroscopic transport properties Renaud Toussaint ; Knut Jørgen M

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

    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

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

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

    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 ...

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

    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...

  7. Osmotic pressure and polymer size in semidilute polymer solutions under good-solvent conditions.

    Pelissetto, Andrea

    2008-07-28

    We consider the lattice Domb-Joyce model at a value of the coupling for which scaling corrections approximately vanish and determine the universal scaling functions associated with the osmotic pressure and the polymer size for semidilute polymer solutions (c/c( *)self-avoiding walks. We show that for c/c( *) greater than or approximately equal 6 simulations of lattice self-avoiding walks give results that are affected by strong scaling corrections even for chain lengths as large as 1000: The self-avoiding walk model is therefore unsuitable for the determination of universal properties of polymer solutions deep in the semidilute regime. PMID:18681672

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

    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...

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

    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.

  10. Creep failure of a reactor pressure vessel lower head under severe accident conditions

    A severe accident in a nuclear power plant could result in the relocation of large quantities of molten core material onto the lower head of he reactor pressure vessel (RPV). In the absence of inherent cooling mechanisms, failure of the RPV ultimately becomes possible under the combined effects of system pressure and the thermal heat-up of the lower head. Sandia National Laboratories has performed seven experiments at 1:5th scale simulating creep failure of a RPV lower head. This paper describes a modeling program that complements the experimental program. Analyses have been performed using the general-purpose finite-element code ABAQUS-5.6. In order to make ABAQUS solve the specific problem at hand, a material constitutive model that utilizes temperature dependent properties has been developed and attached to ABAQUS-executable through its UMAT utility. Analyses of the LHF-1 experiment predict instability-type failure. Predicted strains are delayed relative to the observed strain histories. Parametric variations on either the yield stress, creep rate, or both (within the range of material property data) can bring predictions into agreement with experiment. The analysis indicates that it is necessary to conduct material property tests on the actual material used in the experimental program. The constitutive model employed in the present analyses is the subject of a separate publication

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

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

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

    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.

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

    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.

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

    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.

  15. The dynamic pressure measurements of the nuclear reactor coolant for condition-based maintenance of the reactor

    The condition-based maintenance of the nuclear reactor, by monitoring and measuring the instantaneous dynamic pressure distribution of the coolant (water) impact on the solid surfaces of the reactor during operation is presented. The behaviour of water domes (jets) produced by underwater explosions of small changes of P.E.T.N. at various depths in two different size cylindrical containers, which simulate the nuclear reactor, is investigated. Water surface domes (jets) from the underwater explosions are photographed. Depending on the depth of the charge, curved and flat top jets of up to 455 mm diameter and impact speeds of up to 70 m/sec. are observed. The instabilities in the dome surfaces are observed and the instantaneous profiles are analysed. It is found that, in all cases tested, the maximum pressure takes place at the center of the jet and could reach up to 3.0 times the on-dimensional impact pressure value. The use of their measurements, as online monitoring for condition-based maintenance and design-out maintenance is discussed. 18 refs

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

    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)

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

    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....

  18. Evaluation of hydraulic and mechanical properties of Berea sandstone under different conditions of temperature and confining pressure

    The isotropic compression experiments using Berea sandstone were conducted under the different temperature and confining pressure conditions, and the evolutions of hydraulic and mechanical properties were observed. The temperatures and confining pressures prescribed for the experiments are 20 and 90degC, and 7.5 or 8.0 MPa, respectively. The observed permeability at 20degC did not significantly evolve during the experiment period, while that at 90degC decreased by roughly 20% relative to the original value. This reduction may be attributed to the change of pore-structure induced by mineral dissolution and/or precipitation. Unlikely, the uniaxial compression tests showed no obvious change observed between pre- and post-experimental results. The XRD observation also showed no significant difference of mineralogy between them. (author)

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

    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

  20. Failure strains and proposed limit strains for an reactor pressure vessel under severe accident conditions

    The local failure strains of essential design elements of a reactor vessel are investigated. The size influence of the structure is of special interest. Typical severe accident conditions including elevated temperatures and dynamic loads are considered. The main part of work consists of test families with specimens under uniaxial and biaxial load. Within one test family the specimen geometry and the load conditions are similar, but the size is varied up to reactor dimensions. Special attention is given to geometries with a hole or a notch causing non-uniform stress and strain distributions typical for the reactor vessel. A key problem is to determine the local failure strain. Here suitable methods had to be developed including the so-called 'vanishing gap method', and the 'forging die method'. They are based on post-test geometrical measurements of the fracture surfaces and reconstructions of the related strain fields using finite element models. The results indicate that stresses versus dimensionless deformations are approximately size independent up to failure for specimens of similar geometry under similar load conditions. Local failure strains could be determined. The values are rather high and size dependent. Statistical evaluation allow the proposal of limit strains which are also size dependent. If these limit strains are not exceeded, the structures will not fracture

  1. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    Li, Ying; Manolache, Sorin; Qiu, Yiping; Sarmadi, Majid

    2016-02-01

    In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

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

    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

  3. The influence of testing conditions on burst pressure assessment for inconel tubing

    Because at the lack of normalization for burst testing of tubes with TWD flaws, large divergences are observed between laboratory results. This could result in either unsafe or unduly penalizing consequences. Testing flawed tubes under representative conditions (high leak rate without any sealing provision) yielded results matching previous laboratory data that were obtained with a locally reinforced bladder. This should not be construed to validate any similar laboratory technique, as the particular combination of materials (plastic and metal) strength and thickness, together with other testing details (such as load rate) may affect the results. (author)

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

    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.

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

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

    2009-02-15

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

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

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

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

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

  8. Fabrication of High-Pressure Cold-Sprayed Coating on Ni-Based Superalloy for High-Temperature Corrosive Conditions

    Singh, Harminder

    2015-11-01

    The surface behavior of the Ni-based superalloy (composition similar to UNS N06075) is altered in this study by depositing a 298- µm-thick coating for various erosive-corrosive and wear applications at a high temperature. The 50%Ni-50%Cr coating was developed by a high-pressure cold-spraying method. The coating microstructure was studied by various characterization techniques. The unmelted solid particles formed the coating structure, which is homogeneous, dense, hard, and free from cracks, oxides, and other defects. The coating composition and microstructure is suitable for providing protection to the substrate under high-temperature corrosive conditions. The developed coating performed well, with degradation rate of 0.47 mm/year, in the chlorine-based highly corrosive conditions of actual waste incinerator at 900°C.

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

    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.

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

    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

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

    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.

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

    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

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

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

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

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

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

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

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

    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)

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

    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).

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

    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.

  20. The Influence of Collar on Surge Pressure Caused by the Drilling Fluid Viscous Force under Pumping Condition

    Jun Li; Zhen Huang; Ke Li; Wei Wu

    2013-01-01

    The study of surge pressure is of significant importance for the safety of drilling process because field practice shows that the surge pressure caused by fluid viscous force can cause a great damage to the drilling operation. The accurate calculation of surge pressure is directly related to the safety of the drilling process. However, the existing surge pressure models rarely take the impact of the collar into consideration and thus will inevitably affect the precision of the surge pressure ...

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

    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

  2. Development of Evaluation Technique for Hydrogen Embrittlement Behavior of Metallic Materials Using in-situ SP Testing under Pressurized Hydrogen Gas Conditions

    Recently, alternative and novel energy resources have been developed for use in the future because of the current environmental problems and exhaustion of fossil energy resources. Hydrogen energy has many merits, such as its environmental friendliness, easy storage, and easy production, but it also has disadvantages, in that it is highly combustible and explosive. In this study, a test procedure using a simple SP test under highly pressurized hydrogen gas conditions was established. In order to evaluate its applicability, SP tests were carried out using a stainless steel (SUS316L) sample under atmospheric, pressurized helium, and pressurized hydrogen gas conditions. The results under the pressurized hydrogen gas condition showed fissuring and produced a reduction of the elongation in the plastic instability region due to hydrogen embrittlement, showing the effectiveness of the current in-situ SP test

  3. Influencing factors research on CHF at low pressure, low flow conditions in narrow channel based on Rough Set Decision Model

    Highlights: • This article is consistent with the theme of the thermal–hydraulic. • It provides a new mathematical method for the analysis of the factors affecting the CHF (Critical Heat Flux). • Also it has a great potential for research related to CHF. - Abstract: CHF (Critical Heat Flux) is an important nuclear thermal–hydraulic parameter, and it is closely related to the reactor safety. Based on Rough Set Decision Model, this article proposed a new method to seek for the main factors which may affect CHF at low pressure, low flow conditions in narrow channels. Nine condition attributes are selected to build the CHF fault diagnosis model in narrow rectangular channels, and the rules of CHF occurring are obtained. These attributes include pipe diameter, circulating mode and flow stability, etc. The results show that flow instability could cause the CHF reach a minimum and CHF could be improved with the increase of pipe size. Diagnostic results in this method could predict the main influencing factors for CHF very well, and provide a new theoretical approach for the safety analysis of nuclear plants

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

    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)

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

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

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

  7. 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

    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.

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

    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)

  9. A study on the numerical instability of COBRA-series subchannel analysis codes at low-pressure and low-flow conditions

    The numerical instability at low-pressure and low-flow conditions has been confirmed to be the common problem of the existing COBRA-series subchannel analysis codes. In addition, the range of operating conditions at which the analyses by the codes are impossible has been evaluated. To evaluate the MATRA's inapplicable range of operating conditions of the SMART core that is to be operated at the low flow condition, i.e. about 30% of the flow of the existing commercial pressurized water reactors at the steady-state condition, the analyses of various operating conditions were performed by using several representative COBRA-series subchannel analysis codes including MATRA. TORC of CE, COBRA3CP of Siemens/KWU, COBRA4I of PNL, and MATRA of KAERI were chosen as the subchannel analysis codes to be evaluated. The various operating conditions used in the CHF tests carried out at the Winfrith Establishment of UKAEA were chosen as the conditions to be analyzed. As the result, the numerical instabilities at low-pressure and low-flow conditions occurred in the analyses by all of the codes. It was revealed that the MATRA code, which numerically more stable thatn the other codes, was not able to analyze the conditions of the pressure not more than 100 bar and the mass velocity not more than 300 kg/sec-m2. Hereafter it is required to find out the exact reason for the numerical instability of the existing COBRA-series subchannel analysis codes at low-pressure and low-flow conditions and to devise the new method to get over that numerical problem

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

    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.

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

    Document available in extended abstract form only. We present simulation tests focusing on the drying process around a gallery in an initially saturated (water-filled) porous clay rock, in the framework of a research on the isolation properties and hydro-mechanical behaviour of a clayey geologic repository for radioactive waste. The saturated/unsaturated hydrodynamic parameters used in these tests correspond to a hypothetical clay-stone, similar to the 130 m thick Callovo-Oxfordian formation located between depths 400 m and 600 m at the Meuse / Haute-Marne (MHM) Underground Research Laboratory (URL), operated by ANDRA (Bure, France). The simulations tests were designed according to 3 'types' of computational geometries. The drying period was extended to very long time scales in some cases. The clay rock was taken homogeneous in many tests, but the damaged zone was represented in some (Type III) tests. Type (I) tests are conducted in a simplified non circular geometry. Assuming a square cross-section for the drift, the drying process is obtained by imposing a fixed suction on a flat piece of wall at the roof. The bottom of the porous domain coincides with the roof of the drift. The imposed suction at the roof affects the near field pressure both horizontally and vertically. Type (II) tests reproduce the circular cylindrical geometry of a partially or perfectly filled gallery, with drying conditions imposed at both ends of the drift. Finally, Type (III) tests consider the case of an empty ventilated cylindrical drift with circular cross-section. In this case the drying is imposed on the curved walls of the drift via a transmission mechanism thanks the 'macro-porous immersion' method. In all cases, the drying of the porous clay rock is modeled by imposing a suction condition (ψ), obtained from relative air humidity (HR) via Kelvin's law (ψ). Briefly, the macro-porous immersion method consists in the following interrelated procedures. First, the volumetric excavation

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

    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

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

    Roobol, S. B.; Cañas-Ventura, M. E.; Bergman, M.; van Spronsen, M. A.; Onderwaater, W. G.; van der Tuijn, P. C.; Koehler, R.; Ofitserov, A.; van Baarle, G. J. C.; Frenken, J. W. M.

    2015-03-01

    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.

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

    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.

  15. Calculation of the conditions of crack initiation and arrest during a pressurized thermal shock in the material of the WWER-440 reactor pressure vessel

    The initiation and arrest of a semi-elliptical surface crack in the WWER-440 reactor pressure vessel was treated. The stress from the pressurized thermal shock was determined by finite element calculations. The code was written in the C computer language. No arrest of the initiated crack was achieved for the various crack axis ratios and transient temperatures applied; there are two apparent reasons for this, viz., that the thermal shock failed to be strong enough, and that there is a rather large difference between fracture toughness KIC and KIA, the fracture toughness characterizing the material resistance against a running crack. (P.A.). 2 figs., 5 refs

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

    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.

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

    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.

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

    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.

  19. Continuous enrichment culturing of thermophiles under sulfate and nitrate-reducing conditions and at deep-sea hydrostatic pressures.

    Houghton, J L; Seyfried, W E; Banta, A B; Reysenbach, A-L

    2007-03-01

    A continuous culture bioreactor was developed to enrich for nitrate and sulfate reducing thermophiles under in situ deep-sea pressures. The ultimate objective of this experimental design was to be able to study microbial activities at chemical and physical conditions relevant to seafloor hydrothermal vents. Sulfide, sulfate and oxide minerals from sampled seafloor vent-chimney structures [East Pacific Rise (9 degrees 46'N)] served as source mineral and microbial inoculum for enrichment culturing using nitrate and sulfate-enriched media at 70 and 90 degrees C and 250 bars. Changes in microbial diversity during the continuous reaction flow were monitored using denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16S rRNA gene fragments. Time series changes in fluid chemistry were also monitored throughout the experiment to assess the feedback between mineral-fluid reaction and metabolic processes. Data indicate a shift from the dominance of epsilon Proteobacteria in the initial inoculum to the several Aquificales-like phylotypes in nitrate-reducing enrichment media and Thermodesulfobacteriales in the sulfate-reducing enrichment media. Methanogens were detected in the original sulfide sample and grew in selected sulfate-enriched experiments. Microbial interactions with anhydrite and pyrrhotite in the chimney material resulted in measurable changes in fluid chemistry despite a fluid residence time only 75 min in the reactor. Changes in temperature rather than source material resulted in greater differences in microbial enrichments and mediated geochemical reactions. PMID:17221162

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

    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...

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

    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

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

    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

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

    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

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

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

    2014-12-01

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

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

    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...

  6. Hydrogen transfer hydrocracking of C. procera latex under ambient pressure conditions to get value added chemicals and fuels

    Sharma, D.K.; Behera, B.K.; Arora, M. (Indian Institute of Technology, New Delhi (India). Fuels and Biofuels Engineering Lab.)

    1994-01-01

    Biomass is renewable source of energy while the reserves of petroleum are being depleted. The latex of a potential petrocrop, Calotropis procera, a laticifer, arid-plant which is rich in hydrocarbon type triterpene compounds etc. was found to be a better feed stock for thermal hydrocracking as compared to whole plant biomass in terms of liquid product yield. Studies of chemical reaction dynamics of the thermal cracking of latex at 200-400[degree]C showed that the process should be termed as hydrogen-transfer (H-T) hydrocracking of latex under ambient pressure conditions. The hydrogen rich cracked triterpenoids act as the H-donors in this process, where nascent hydrogen atoms and free radicals chemically plug the cracked moieties to stabilise these. Latex was also coagulated and the H-T hydrocracking of the feedstock coagulum gave a higher yield of cracked oil in comparison to that from the dried latex. The temperature for hydrocracking of latex has been optimized to 350[degree]C and molecular sieve was found to catalyse the H-T hydrocracking process to yield more liquid product. The distillation range of cracked latex oil (CLO) obtained from H-T hydrocracking of C. procera latex indicated that it can be used as fuel oil or substitute for diesel fuel. Moreover, CLO resembled diesel fuels and was predominantly paraffinic in nature as characterised by NMR and FTIR spectral analysis. A process has been recommended for getting value added fuels and chemicals from C. procera latex. 29 refs., 5 figs., 3 tabs.

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

    Feddema, Rick

    Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements. Fuel injector spray atomization performance is affected by the type of fuel injector, fuel liquid properties, fuel injection pressure, fuel injection temperature, and ambient pressure. Performance of pressure swirl atomizer and hybrid air blast nozzle type fuel injectors are compared in this study. Aviation jet fuels, JP-8, Jet A, JP-5, and JP-10 and their effect on fuel injector performance is investigated. Fuel injector set conditions involving fuel injector pressure, fuel temperature and ambient pressure are varied in order to compare each fuel type. One objective of this thesis is to contribute spray patternation measurements to the body of existing drop size data in the literature. Fuel droplet size tends to increase with decreasing fuel injection pressure, decreasing fuel injection temperature and increasing ambient injection pressure. The differences between fuel types at particular set conditions occur due to differences in liquid properties between fuels. Liquid viscosity and surface tension are identified to be fuel-specific properties that affect the drop size of the fuel. An open aspect of current research that this paper addresses is how much the type of aviation jet fuel affects spray atomization characteristics. Conventional aviation fuel specifications are becoming more important with new interest in alternative

  8. Definition of routine conditions of transport: a perspective on pressure and temperature for excepted and industrial packages as required by ST-1

    The implementation of ST-1 will bring a change to the requirements for packages to withstand ambient temperatures and pressures that are likely to be encountered in routine transport. This paper, making use of published data, postulates an environment and then considers the physical effect of that environment on excepted and industrial packages. The effect of atmospheric pressure changes is considered together with pressures arising from ambient temperature changes. Assuming a constant volume the pressure that could be developed within a package is estimated to be 21.4 kPa for transport in the UK at the highest road elevation. This equates to a volume change of 23% assuming constant pressure and variable volume. The constant pressure case is applicable to a wrapped or bagged package and the constant volume to a drum. Information from a major drum manufacturer indicates that a standard 200 litre drum may experience deformation of the lid beyond its elastic limit (particularly if the route is over mountain passes), although it is still likely to retain its contents (up to a pressure differential of 100 kPa). The paper poses the following questions: (1) Are the conditions considered for the UK realistic and acceptable to the Competent Authority? If not what should be used? (2) Is a drum capable of withstanding a 1.2 m drop test in its pressurised configuration, or does it have to? (3) Is there operational experience which refutes or supports the above?. (author)

  9. Constraining the Depth of a Martian Magma Ocean through Metal-Silicate Partitioning Experiments: The Role of Different Datasets and the Range of Pressure and Temperature Conditions

    Righter, K.; Chabot, N.L.

    2009-01-01

    Mars accretion is known to be fast compared to Earth. Basaltic samples provide a probe into the interior and allow reconstruction of siderophile element contents of the mantle. These estimates can be used to estimate conditions of core formation, as for Earth. Although many assume that Mars went through a magma ocean stage, and possibly even complete melting, the siderophile element content of Mars mantle is consistent with relatively low pressure and temperature (PT) conditions, implying only shallow melting, near 7 GPa and 2073 K. This is a pressure range where some have proposed a change in siderophile element partitioning behavior. We will examine the databases used for parameterization and split them into a low and higher pressure regime to see if the methods used to reach this conclusion agree for the two sets of data.

  10. Heat transfer parameters for glass-peened calandria tube in pressure tube and calandria tube contact conditions

    During a postulated event of large LOCA in CANDU reactors, the pressure tube may balloon to contact with its surrounding calandria tube to transfer heat to the moderator. To confirm the integrity of the fuel channel after the contact with a given moderator subcooling, many experiments have been performed in the last three decades by applying different pressure tube heatup rates, different pressure tube pressures and different moderator subcoolings for calandria tubes with smooth outer surface and glass-peened surface. A concept of Equivalent Moderator Subcooling (EMS) has been put forward to determine integrity of fuel channel upon pressure tube/calandria tube contact based on the existing experiment results. This concept has been presented in another work. In this work, the contact thermal conductance between pressure tube and calandria tube, critical heat flux, minimum film boiling temperature, empirical methods for nucleate boiling and film boiling heat transfer coefficient on the glass-peened calandria tube surface are discussed and estimated based on some experimental results and the EMS concept. These parameters are confirmed by simulating the existing experiments using a computer code. The estimated results may help detailed analyses on fuel channel integrity upon PT/CT contact if necessary. (author)

  11. Delayed hydride cracking velocity of Zr-1Nb-1.4Sn-0.3Fe pressure tube with different environmental conditions

    Delayed hydride cracking velocity of a Zr-1Nb-1.4Sn-0.3Fe tube was evaluated in air and pressurized water to investigate the effect of the environmental conditions on the DHC characteristics. Compact tension specimens charged electrolytically with 29 to 60 ppm H were subjected to DHC tests at temperature ranging from 144 to 250 .deg. C. DHC velocity increased with increasing temperature but was slightly higher in pressurized water conditions than air. This environmental effect on DHCV of the Zr-1Nb-1.4Sn-0.3Fe tube appeared striking at low temperature but disappeared at the temperature as high as 250 .deg. C. A discussion was made on the effect of the environmental conditions on DHCV of the Zr-1Nb-1.4Sn-0.3Fe tube. For the 001 sake of the safety of pressure tubes operating in reactors, DHCV velocity obtained in pressurized water seems more valid than that in air

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

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

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

    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)

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

    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

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

    Svoboda, Karel; Hartman, Miloslav; Čermák, Jiří; Pohořelý, Michael

    2001-01-01

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

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

    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

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

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

    2015-01-01

    Roč. 206, April (2015), s. 34-41. ISSN 1387-1811 Institutional support: RVO:67985831 Keywords : paulingite * high pressure * X-ray diffraction * compressibility * crystal–fluid interaction Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.453, year: 2014

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

    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.

  19. Grid spacer effect on reflood behavior observed at reflood experiment with 5 x 5 bundle test section under wide pressure condition

    There are a lot of works on quenching behavior and minimum film boiling temperature. However, these phenomena are not clear enough for high-pressure condition. Therefore, reflood experiments were performed with 5 x 5-bundle test section under pressure of 2 MPa to 15.5 MPa. Geometry of a bundle test section used at the present experiments was principally the same as that of conventional PWRs. Grid spacers used at the present experiments were designed to simulate conventional ones. Data on clad temperature transient, quench time, and heat transfer coefficient were obtained. Quenching took place at several elevations where grid spacers located, and then each quenching front propagated downstream, or toward upper elevations under high mass flux condition. Thus, grid spacers showed influence of significant promotion of quenching occurrence above grid spacers. This promotion is more significant at higher mass flux and slightly significant at higher pressure. Under such condition, grid spacer effect is not negligible to analyze thermal-hydraulics accurately for PWRs and BWRs accidents. On the other hand, grid spacer effect on quenching occurrence is small at lower mass flux and lower pressure. The boundary of above two cases was determined experimentally. In order to study above characteristics, heat transfer coefficient distribution along the distance of the grid spacer was investigated. Heat transfer coefficient was enhanced above grid spacers and the enhancement was decayed along the distance of the grid spacer. The enhancement at the grid spacer was significant at higher mass flux. Relaxation length of grid spacer effect was about 0.1 m. Thus, effects of mass flux and pressure on promotion of quenching occurrence is explained by heat transfer enhancement above the grid spacers. (author)

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

    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.

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

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

  2. 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

    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...

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

    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.

  4. Results of calculation investigation into accidental conditions with an open relief valve in the pressurizer of the WWER-440 reactor

    A hypothetical accident with an open relief valve of the pressurizer is considered for the Kozlodyj NPP reactor. The valve opens as a result of small breaks in the reactor primary circuit. The numerical computation study was conducted with the use of the RELAP4/MOD program. The investigation was carried out in the supposition that the accident proceeds with the design protection system operating. The studies have shown that no violation in the primary circuit natural circulation takes place when the valve opens and design protection system actuates. Cool-down of the primary circuit with the use of a fast-response reduction-cooling facility is reasonable for the accident in question; that would reduce coolant losses with a decrease in the primary circuit pressure and enable to turn on the emergency filling pumps of the reactor core later on

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

    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

  6. CO{sub 2}/water interfacial tensions under pressure and temperature conditions of CO{sub 2} geological storage

    Chiquet, Pierre [Laboratoire des fluides complexes, UMR 5150, Universite de Pau et des Pays de l' Adour, 64013 Pau-Cedex (France); Centre Scientifique et Technique Jean Feger, TOTAL, avenue Larribau, 64018 Pau Cedex (France); Daridon, Jean-Luc [Laboratoire des fluides complexes, UMR 5150, Universite de Pau et des Pays de l' Adour, 64013 Pau-Cedex (France); Broseta, Daniel [Laboratoire des fluides complexes, UMR 5150, Universite de Pau et des Pays de l' Adour, 64013 Pau-Cedex (France)]. E-mail: daniel.broseta@univ-pau.fr; Thibeau, Sylvain [Centre Scientifique et Technique Jean Feger, TOTAL, avenue Larribau, 64018 Pau Cedex (France)

    2007-03-15

    CO{sub 2} storage in aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing CO{sub 2} atmospheric concentration. However, its implementation in a given reservoir requires demonstration that CO{sub 2} leakage through the reservoir seal (caprock) is extremely limited. One possible cause of rapid leakage is capillary failure of the caprock, which is to a large extent controlled by the CO{sub 2}/water interfacial tension (IFT). This paper presents pendant drop measurements of IFTs between water and CO{sub 2} in a range of temperatures (308-383 K) and pressures (5-45 MPa) relevant to CO{sub 2} storage in deep geological formations. Phase densities were measured simultaneously, allowing precise IFT determinations. Increasing the pressure along a given isotherm, IFTs were observed to decrease sharply, then to level off and reach, for pressures above 20 MPa, a pseudo-plateau that decreases slightly with temperature, from around 30 mN/m at 308 K to 23 mN/m at 383 K. The presence of salt (20 g/l NaCl) in the water phase has a negligible effect on the IFT. An important conclusion for CO{sub 2} storage is that CO{sub 2}/brine IFTs have low but reasonable values (higher than 20 mN/m) even at the highest pressures and temperatures examined, and that, neglecting all other possible effects, CO{sub 2} storage can, therefore, be considered even in deep geological formations.

  7. Injection of CO2 at Ambient Temperature ConditionsPressure and Temperature Results of the “cold injection” Experiment at the Ketzin Pilot Site

    F. Moeller; A. Liebscher; S. Martens; Cornelia Schmidt-Hattenberger; M. Streibel

    2014-01-01

    From June 2008 to August 2013, slightly more than 67 kt of CO2 were injected at the Ketzin pilot site (Brandenburg, Germany). The CO2 reservoir is a saline aquifer at a depth of 630 – 650 m with initial pressure and temperature conditions of about 33 °C/62 bar. These reservoir conditions are near the critical point of pure CO2 (31.0 °C/73.8 bar) and the CO2 liquid-vapour equilibrium. In order to avoid phase transitions and near-critical phenomena throughout the injection process the CO2, whic...

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

    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

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

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

  10. Photovoltaic barometer; Barometre photovoltaique

    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)

  11. Photovoltaic barometer; Barometre photovoltaique

    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

  12. Biogas barometer; barometre biogaz

    Anon.

    2010-11-15

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

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

    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.

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

    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

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

    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

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

    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)

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

    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.

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

    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.

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

    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)

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

    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

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

    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.

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

    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.

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

    Russin, W. R.

    1974-01-01

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

  4. Externally controlled pressure and temperature microreactor for in situ x-ray diffraction, visual and spectroscopic reaction investigations under supercritical and subcritical conditions

    A microreactor has been developed for in situ, spectroscopic investigations of materials and reaction processes with full external pressure and temperature control from ambient conditions to 400 deg. C and 310 bar. The sample chamber is in direct contact with an external manifold, whereby gases, liquids or fluids can be injected and their activities controlled prior to and under investigation conditions. The microreactor employs high strength, single crystal moissanite windows which allow direct probe beam interaction with a sample to investigate in situ reaction processes and other materials properties. The relatively large volume of the cell, along with full optical accessibility and external temperature and pressure control, make this reaction cell well suited for experimental investigations involving any combination of gas, fluid, and solid interactions. The microreactor's capabilities are demonstrated through an in situ x-ray diffraction study of the conversion of a meta-serpentine sample to magnesite under high pressure and temperature. Serpentine is one of the mineral candidates for the implementation of mineral carbonation, an intriguing carbon sequestration candidate technology

  5. Synthesis and optical property of large-scale centimetres-long silicon carbide nanowires by catalyst-free CVD route under superatmospheric pressure conditions.

    Lin, Liangwu

    2011-04-01

    Large-scale centimetres-long single-crystal β-SiC nanowires have been prepared using CH(4) as the carbon source and SiO or the mixture of Si and SiO(2) as the silicon source by a simple catalyst-free CVD route under superatmospheric pressure conditions. The nanowries grown on ceramic boat or corundum substrates, with lengths of several centimetres and the average diameters of around 40 nm, were composed of single-crystal β-SiC core along the [111] direction and amorphous SiO(2) shell of about 1-30 nm thick depending on the growth position along the flowing direction of the carrier gas. The total gas pressure is an important factor for the synthesis of the large-scale centimetres-long β-SiC nanowires, which can easily adjust the pressure of the vapors to supersaturation condition. The growth of the nanowires was governed by the Vapor-Solid mechanism. The β-SiC nanowires showed an intense blue light emission at room temperature. PMID:21305091

  6. Precise evaluation of corrosion environments of structural materials under complex water flow condition, (1). Estimation of corrosion potentials in reactor pressure vessel bottom of BWRs

    To estimate the corrosion potentials of structural materials under complex water flow condition, such as reactor pressure vessel (RPV) bottom region of Boiling Water Reactors (BWRs), a method was newly developed. Three-dimensional water flow analysis was performed and corrosion potentials of structural materials were calculated on the basis of the flow analysis results. Water flow analysis showed the velocities in the RPV bottom region varied from about 0.1 ms-1 to 4.5 ms-1. From the corrosion potential estimation under hydrogen water chemistry (HWC) condition, at the jet pump outlet and shroud support leg, a rather large amount of hydrogen had to be added to reduce the potential because of high flow velocity condition. Conversely, a small amount of hydrogen was sufficient in the case of the stub tube of the control rod drive (CRD) guide tubing located in the center of the bottom region. (author)

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

    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.

  8. High temperature post-irradiation performance of spent pressurized-water-reactor fuel rods under dry-storage conditions

    Post-irradiation studies on failure mechanisms of well characterized PWR rods were conducted for up to a year at 482, 510 and 5710C in unlimited air and inert gas atmospheres. No cladding breaches occurred even though the tests operated many orders of magnitude longer in time than the lifetime predicted by Blackburn's analyses. The extended lifetime is due to significant creep strain of the Zircaloy cladding which decreases the internal rod pressures. The cladding creep also contributes to radial cracks, through the external oxide and internal FCCI layers, which propagated into and arrested in an oxygen stabilized α-Zircaloy layer. There were no signs of either additional cladding hydriding, stress-corrosion cracking or fuel pellet degradation. Using the Larson-Miller formulization, a conservative maximum storage temperature of 4000C is recommended to ensure a 1000-year cladding lifetime. This accounts for crack propagation and assumes annealing of the irradiation-hardened cladding

  9. The Costs of Parental Pressure to Express Emotions: Conditional Regard and Autonomy Support as Predictors of Emotion Regulation and Intimacy

    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…

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

    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.

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

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

    2007-01-01

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

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

    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.

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

    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 ZrCl4 is lower than 1 × 10−11 weight fraction if electrorefining is finished before anode potential reaches −1.8 V (vs. Cl2/Cl−)

  14. 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

    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.

  15. 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

    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)

  16. Reaction kinetics and solubilities of corrosion products in the physicochemical conditions of the primary circuit of pressurized water reactors (PWR)

    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)

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

    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...

  18. 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

    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

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

    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.

  20. 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

    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

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

    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.

  2. Macroscopic electric field and osmotic pressure in ultracentrifugal sedimentation-diffusion equilibria of charged colloids

    Sedimentation-diffusion (SD) equilibria from analytical ultracentrifugation of well-characterized charged silica spheres in ethanol deviate strongly from a barometric profile and demonstrate the existence and substantial effects of a recently predicted internal macroscopic electric field (van Roij 2003 J. Phys.: Condens. Matter 15 S3569). Experimental SD-profiles yield the gradient of the electrostatic potential energy of the colloids, which clearly manifests an almost homogeneous macroscopic electric field. Electrochemical Donnan potential measurements confirm a difference in electrical potential between the top and bottom of the profiles. A 'non-barometric' limiting law derived from electroneutrality explains the trends in the SD-profiles quite well. Our analysis of osmotic pressures (obtained from integrating SD-profiles) beyond this simple law includes, among other things, colloid-ion attractions and extra volume terms in the free energy

  3. Crack initiation and crack growth during thermal shock tests in the reactor pressure vessel of the HDR under corrosive medium conditions

    A survey is presented of the status of comprehensive thermal shock investigations performed at a reactor pressure vessel (RPV). In a separate group of experiments it was first studied which impacts are exerted on the undamaged RPV wall by fluid transients resembling emergency cooling conditions. Furthermore, crack formation and crack growth were enforced in selected wall zones by providing appropriate boundary conditions. It is proposed to load in a final step the wall zones heavily damaged by quasi-reality crack fields under conditions similar to emergency cooling. The investigations are performed to verify the capability of non-destructive testing methods and of computations (of temperatures, stresses, crack behaviour) to provide relevant information. The computations have yielded clear overestimations as well as underestimations. For instance, the investigations performed at the plant proper have produced the result that the thermal shocks acting on the RPV wall surface are substantially reduced by thermal mixing processes in water. In the subsequent computations of the RPV wall structure, rotation symmetric computer codes are found to fail completely under conditions of intensive local cooling. Finally - although the crack growth computations for the special cyclic thermal shocks under corrosive medium conditions were extremely conservative - it has been demonstrated, by use of acoustic emission analysis and other techniques that the present crack growth computations do not adequately take into account crucial parameters influencing the material behaviour. This means that the results obtained with laboratory-scale specimens cannot be safely transferred to the components under the testing conditions prevailing for the time being. (author)

  4. 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

    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.

  5. Application of Structural Reliability to support deterministic integrity analyses of Reactor Pressure Vessel subjected to transient conditions

    The benefits of a probabilistic approach compared to the more conventional deterministic method are the clear treatment of uncertainties and the possibility to perform sensitivity studies from which it is possible to identify and quantify the effect of key factors and mitigative actions. They thus provide information to support optimal decisions related to in-service inspection planning and maintenance strategies, lifetime prediction or reassessment, integrity assessment of degradation and definition of in-service acceptability criteria. Apart from a clear modelling of fracture mechanics concept and detailed knowledge of the input data, application of this type of analysis requires a tool capable of making a reasonably easy numerical estimate of the probability of failure. For this purpose a benchmark problem has been performed by EDF, Framatome and CEA to clarify the difficulties and differences in numerical processes. In this study, general state-of-the-art structural reliability methods known as First and Second Order Reliability Methods (FORM/SORM) along with Monte Carlo Simulation and Importance Sampling were tested on a rather complex mechanical model. This model concerns the risk of brittle rupture of a PWR vessel subjected to transient conditions. The objective of this paper is to present the results of this benchmark exercises used also to validate the probabilistic model and its input random parameters. By performing sensitivity studies and analyzing the coordinate value of the design point (most probable failure point given by FORM method), the most influential parameters have been identified on this case study. Special data base have therefore been collected and sophisticated statistical treatment performed to update more precisely the probability distribution of these parameters (the fracture toughness transition curve, the irradiation-induced shift prediction, the flaw size, the reliability of NDE...). Results from these probabilistic analyses can now

  6. Effect of surface conditions on transient critical heat fluxes for a horizontal cylinder in a pool of water at pressures due to exponentially increasing heat inputs

    The transient critical heat fluxes, CHFs, on 1.2-mm horizontal cylinders with mirror finished surface (MS) and Emery-3 finished rough one (RS) in a pool of water due to exponentially increasing heat inputs, Q0et/τ, with the periods, τ, ranged from 20 s down to 2 ms at pressures ranging from atmospheric up to 2 MPa for the subcoolings ranging from 0 to 80 K were measured. A heat input with the period of 20 s corresponds to quasi-steadily increasing one. The obtained data compared with the corresponding data for a cylinder with commercial surface (CS) which were already published in other papers. The trend of CHFs for the periods was generally as follows: the CHF first increases with a decrease in period up to a certain maximum CHF, then it decreases down to a minimum CHF and finally again increases with a decrease in period; namely the CHFs for the periods are separated into the first, second and third groups for longer, shorter and intermediate periods, respectively. The three groups of the CHFs for the periods tested were clearly observed for the cylinders with MS and RS, though the CHFs values for the shorter periods belonging to the second group were not observed for the cylinder with CS except those for the saturation condition at around atmospheric pressure, and those for high subcoolings at higher pressures. At the CHFs belonging to the second group the direct or semi-direct transition clearly occurs from transient conduction regime to film boiling without or with the vapor bubbles for a while with instantaneous increasing of heat flux for both cylinders of MS and RS. It was assumed that the transitions at the CHFs occur due to the explosive-like heterogeneous spontaneous nucleation (HSN) in originally flooded cavities similar to the assumption for the cylinder with CS previously published. It should be noted that as a typical example the minimum CHFs for the periods of 10 ms on the MS and RS cylinders at the pressure of 1 MPa for the subcooling of 40 K

  7. Effect of surface conditions on transient critical heat fluxes for a horizontal cylinder in a pool of water at pressures due to exponentially increasing heat inputs

    The transient critical heat fluxes, CHFs, on 1.2mm horizontal cylinders with mirror finished and Emery-3 finished rough surfaces(MS, RS) in a pool of water due to exponentially increasing heat inputs, Qoet/τ, with the periods, τ, ranged from 20s down to 2ms at the pressures ranging from atmospheric up to about 2MPa for the subcoolings ranging from zero up to 80K were measured: the heat input with the period of 20s corresponds to quasi-steadily increasing one. The data compared with the corresponding data for the cylinder with commercial surface(CS). The trend of CHFs for the periods was generally as follows: the CHF first increases with the decrease in period up to a certain maximum CHF, then it decreases down to a minimum CHF and again increases with the decrease in period; namely the CHFs for the periods are separated into the 1st, 2nd and 3rd groups for longer, shorter and intermediate periods respectively. The three groups of the CHFs were clearly observed for the cylinders with MS and RS though the CHFs values for the shorter periods were not observed for the cylinder with CS except those for the saturation condition at around atmospheric pressure, and those for high subcoolings at higher pressures. At the CHFs belonging to the 2nd group the direct or semi-direct transition clearly occurs from transient conduction regime to film boiling without or with the vapor bubbles for a while with instantaneous increasing of heat flux for both cylinders of MS and RS; at the CHFs the transitions occur due to the explosive-like heterogeneous spontaneous nucleation in originally flooded cavities. It should be noted that as a typical example the minimum CHFs for the periods of 10ms on the MS and RS cylinders at the pressure of 1MPa for the subcooling of 40K were about 40% of the corresponding steady-state CHF. It was observed that the trend of CHFs for the 2nd and 3rd groups are significantly affected by the cylinder surface conditions. (J.P.N.)

  8. Structural Phase Transition in CdSb + 3 % MnSb Composite at a High Hydrostatic Pressure

    R.G. Dzhamamedov

    2015-12-01

    Full Text Available In CdSb + 3 % MnSb composite, structural properties have been studied, specific resistance ρ and Hall coefficient RH are measured at a high hydrostatic pressure of up to P ≤ 9 GPa. An irreversible structural phase transition is found at barometric dependencies p(P and RH(P. From our experimental data, barometric dependencies of carrier concentration and their mobility are calculated. On the basis of the heterophase structure – effective medium model, characteristic points and parameters of the phase transition, and also dynamics of variation of the initial phase volume C1 as a function of pressure are computed. The latter dependence is in agreement with the investigation results of Raman scattering before and after application of pressure.

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

    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

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

    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

  11. Analysis of fuel rod behaviour within a rod bundle of a pressurized water reactor under the conditions of a loss of coolant accident (LOCA) using probabilistic methodology

    The assessment of fuel rod behaviour under PWR LOCA conditions aims at the evaluation of the peak cladding temperatures and the (final) maximum circumferential cladding strains. Moreover, the estimation of the amount of possible coolant channel blockages within a rod bundle is of special interest, as large coplanar clad strains of adjacent rods may result in strong local reductions of coolant channel areas. Coolant channel blockages of large radial extent may impair the long-term coolability of the corresponding rods. A model has been developed to describe these accident consequences using probabilistic methodology. This model is applied to study the behaviour of fuel rods under accident conditions following the double-ended pipe rupture between collant pump and pressure vessel in the primary system of a 1300 MW(el)-PWR. Specifically a rod bundle is considered consisting of 236 fuel rods, that is subjected to severe thermal and mechanical loading. The results obtained indicate that plastic clad deformations with circumferential clad strains of more than 30% cannot be excluded for hot rods of the reference bundle. However, coplanar coolant channel blockages of significant extent seem to be probable within that bundle only under certain boundary conditions which are assumed to be pessimistic. (orig./RW)

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

    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)

  13. Estimation of temperature-induced reactor coolant system and steam generator tube creep rupture probability under high-pressure severe accident conditions

    A severe accident has inherently significant uncertainties due to the complex phenomena and wide range of conditions. Because of its high temperature and pressure, performing experimental validation and practical application are extremely difficult. With these difficulties, there has been few experimental researches performed and there is no plant-specific experimental data. Instead, computer codes have been developed to simulate the accident and have been used conservative assumptions and margins. This study is an effort to reduce the uncertainty in the probabilistic safety assessment and produce a realistic and physical-based failure probability. The methodology was developed and applied to the OPR1000. The creep rupture failure probabilities of reactor coolant system (RCS) components were evaluated under a station blackout severe accident with all powers lost and no recovery of steam generator auxiliary feed-water. The MELCOR 1.8.6 code was used to obtain the plant-specific pressure and temperature history of each part of the RCS and the creep rupture failure times were calculated by the rate-dependent creep rupture model with the plant-specific data. (author)

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

    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.

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

    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.

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

    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.

  17. Effect of meal volume and calorie load on postprandial gastric function and emptying: studies under physiological conditions by combined fiber-optic pressure measurement and MRI.

    Kwiatek, Monika A; Menne, Dieter; Steingoetter, Andreas; Goetze, Oliver; Forras-Kaufman, Zsofia; Kaufman, Elad; Fruehauf, Heiko; Boesiger, Peter; Fried, Michael; Schwizer, Werner; Fox, Mark R

    2009-11-01

    This study assessed the effects of meal volume (MV) and calorie load (CL) on gastric function. MRI and a minimally invasive fiber-optic recording system (FORS) provided simultaneous measurement of gastric volume and pressure changes during gastric filling and emptying of a liquid nutrient meal in physiological conditions. The gastric response to 12 iso-osmolar MV-CL combinations of a multinutrient drink (MV: 200, 400, 600, 800 ml; CL: 200, 300, 400 kcal) was tested in 16 healthy subjects according to a factorial design. Total gastric volume (TGV) and gastric content volume (GCV = MV + secretion) were measured by MRI during nasogastric meal infusion and gastric emptying over 60 min. Intragastric pressure was assessed at 1 Hz by FORS. The dynamic change in postprandial gastric volumes was described by a validated three-component linear exponential model. The stomach expanded with MV, but the ratio of GCV:MV at t(0) diminished with increasing MV (P TGV followed those of GCV. Intragastric pressure increased with MV, and this effect was augmented further by CL (P = 0.02); however, the absolute pressure rise was <4 mmHg. A further postprandial increase of gastric volumes was observed early on before any subsequent volume decrease. This "early" increase in GCV was greater for smaller than larger MV (P < 0.01), indicating faster initial gastric emptying of larger MV. In contrast, volume change during filling and in the early postprandial period were unaffected by CL. In the later postprandial period, gastric emptying rate continued to be more rapid with high MVs (P < 0.001); however, at any given volume, gastric emptying was slowed by higher CL (P < 0.001). GCV half-emptying time decreased with CL at 18 +/- 6 min for each additional 100-kcal load (P < 0.001). These findings indicate that gastric wall stress (passive strain and active tone) provides the driving force for gastric emptying, but distal resistance to gastric outflow regulates further passage of nutrients. The

  18. Pressure transducers

    Strain gauges pressure transducers types are presented. Models, characteristics and calibration procedures were also analysed. Initially, a theoretical study was accomplished to evaluate metallic alloys behavior on sensing elements manufacturing, and diaphragm was used as deflecting elements. Electrical models for potenciometric transducers were proposed at the beginning and subsequently comproved according our experiments. Concerning bridge transducers, existing models confirmed the conditions of linearity and sensitivity related to the electrical signal. All the work done was of help on the calibration field and pressure measurements employing unbounded strain gauge pressure transducers

  19. Effects of pre- or post-processing storage conditions on high-hydrostatic pressure inactivation of Vibrio parahaemolyticus and V. vulnificus in oysters.

    Ye, Mu; Huang, Yaoxin; Gurtler, Joshua B; Niemira, Brendan A; Sites, Joseph E; Chen, Haiqiang

    2013-05-15

    The effects of storage conditions on subsequent high-hydrostatic pressure (HHP) inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in oysters were investigated. Live oysters were inoculated with V. parahaemolyticus or V. vulnificus to ca. 7-8 log MPN/g by feeding and stored at varying conditions (i.e., 21 or 35 °C for 5h, 4 or 10 °C for 1 and 2 days and -18 °C for 2 weeks). Oyster meats were then treated at 225-300 MPa for 2 min at 4, 21 or 35 °C. HHP at 300 MPa for 2 min achieved a >5-log MPN/g reduction of V. parahaemolyticus, completely inactivating V. vulnificus (negative by enrichment) in oysters. Treatment temperatures of 4, 21 and 35 °C did not significantly affect pressure inactivation of V. parahaemolyticus or V. vulnificus (P>0.05). Cold storage at -18, 4 and 10 °C, prior to HHP, decreased V. parahaemolyticus or V. vulnificus populations by 1.5-3.0 log MPN/g, but did not increase their sensitivity to subsequent HHP treatments. The effects of cold storage after HHP on inactivation of V. parahaemolyticus in oysters were also determined. Oysters were inoculated with V. parahaemolyticus and stored at 21 °C for 5h or 4 °C for 1 day. Oyster meats were then treated at 250-300 MPa for 2 min at 21 or 35 °C and stored for 15 days in ice or in a freezer. V. parahaemolyticus populations in HHP-treated oysters gradually decreased during post-HHP ice or frozen storage. A validation study using whole-shell oysters was conducted to determine whether the presence of oyster shells influenced HHP inactivation of V. parahaemolyticus. No appreciable differences in inactivation between shucked oyster meat and whole-shell oysters were observed. HPP at 300 MPa for 2 min at 21 °C, followed by 5-day ice storage or 7-day frozen storage, and HPP at 250 MPa for 2 min at 21 °C, followed by 10-day ice or 7-day frozen storage, completely inactivated V. parahaemolyticus in whole-shell oysters (>7 log reductions). The combination of HHP at a relatively low pressure

  20. Experimental study results on the grounds for the behaviour of high-burnup fuel in pressurized water reactors under conditions of loss of coolant accidents

    The complex of experimental studies is performed with the aim to clarify the behaviour of WWER high-burnup (∼ 60 MW day rg-1 U) fuel elements under conditions of loss of coolant accidents. It is revealed that the gaseous fission products release increases from 15 to 100% with a temperature growth from 1000 to 2500 deg C. The study of oxidation kinetics for irradiated fuel cans of Zr-1% Nb and Eh-635 alloys shows that their oxidation at 1000 deg C is somewhat faster compared to unirradiated cans with a temperatures increase above 1200 deg C this distinction disappears. Short-term mechanical properties of irradiated and unirradiated fuel cans do not differ when the temperature increases up to typical for accident values (> 600 deg C). Brittle fracture in fuel cans is not observed at the temperature below 100 deg C. The temperature dependence of time to fracture is built for the conditions of fuel can loading with excess pressure which is typical for a design basis loss of coolant accident

  1. An application of liquid sublayer dryout mechanism to the prediction of critical heat flux under low pressure and low velocity conditions in round tubes

    Based on several experimental evidences for nucleate boiling in annular film and the existence of residual liquid film flow rate at the critical heat flux (CHF) location, the liquid sublayer dryout (LSD) mechanism under annular film is firstly introduced to evaluate the CHF data at low pressure and low velocity (LPLV) conditions, which would not be predicted by a normal annular film dryout (AFD) model. In this study, the CHF occurrence due to annular film separation or breaking down is phenomenologically modelled by applying the LSD mechanism to this situation. In this LSD mechanism, the liquid sublayer thickness, the incoming liquid velocity to the liquid sublayer, and the axial distance from the onset of annular flow to the CHF location are used as the phenomena-controlling parameters. From the model validation on the 1406 CHF data points ranging over P = 0.1 - 2 MPa, G = 4 - 499 kg/m2s, L/D = 4 - 402, most of CHF data (more than 1000 points) are predicted within ±30% error bounds by the LSD mechanism. However, some calculation results that critical qualities are less than 0.4 are considerably overestimated by this mechanism. These overpredictions seem to be caused by inadequate CHF mechanism classification criteria and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities and a new bubble detachment model for LPLV conditions are needed to improve the model accuracy. (author)

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

    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.

  3. Steady state and stability characteristics of natural circulation loops operating with carbon dioxide at supercritical pressures for open and closed loop boundary conditions

    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

  4. Modelling the chemical behaviour of tellurium species in the reactor pressure vessel and the reactor cooling system under severe accident conditions

    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

  5. The influence of radiative heat exchange on the character of gasdynamic flows under conditions of pulsed discharge in high-pressure cesium vapor

    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.

  6. Tunnel construction work under high earth pressure and springwater flouing condition. Construction details of a pioneer drift for Hida tunnel, Tokai-Hokuriku expressway

    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)

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

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

  8. The Impact of Atmospheric Conditions on the Baseball Totals Market

    Rodney J. Paul; Weinbach, Andrew P.; Chris Weinbach

    2014-01-01

    A study of the physics of baseball has shown that air density plays a significant role in the distance a batted baseball will travel. Air density is a function of altitude, temperature, humidity, and barometric pressure. This paper tests if air density impacts the totals market in Major League Baseball by influencing the number of runs in a game above and beyond the betting market total. Through regression analysis and betting simulations of the 2012 season, it is shown that air density has a...

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

    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

  10. An utilization of liquid sublayer dryout mechanism in predicting critical heat flux under low pressure and low velocity conditions in round tubes

    From a theoretical assessment of extensive critical heat flux (CHF) data under low pressure and low velocity (LPLV) conditions, it was found out that lots of CHF data would not be well predicted by a normal annular film dryout (AFD) mechanism, although their flow patterns were identified as annular-mist flow. To predict these CHF data, a liquid sublayer dryout (LSD) mechanism has been newly utilized in developing the mechanistic CHF model based on each identified CHF mechanism. This mechanism postulates that the CHF occurrence is caused by dryout of the thin liquid sublayer resulting from the annular film separation or breaking down due to nucleate boiling in annular film or hydrodynamic fluctuation. In principle, this mechanism well supports the experimental evidence of residual film flow rate at the CHF location, which can not be explained by the AFD mechanism. For a comparative assessment of each mechanism, the CHF model based on the LSD mechanism is developed together with that based on the AFD mechanism. The validation of these models is performed on the 1406 CHF data points ranging over P=0.1-2 MPa, G=4-499 kg m-2 s-1, L/D=4-402. This model validation shows that 1055 and 231 CHF data are predicted within ±30 error bound by the LSD mechanism and the AFD mechanism, respectively. However, some CHF data whose critical qualities are <0.4 or whose tube length-to-diameter ratios are <70 are considerably overestimated by the CHF model based on the LSD mechanism. These overestimations seem to be caused by an inadequate CHF mechanism classification and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities as well as a new bubble detachment model for LPLV conditions, are needed to improve the model accuracy.

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

    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

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

    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

  13. Study on critical heat flux enhancement in flow boiling of SiC nano-fluids under low pressure and low flow conditions

    Critical heat flux (CHF) is the thermal limit of a phenomenon in which a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the heat transfer efficiency, thus causing localized overheating of the heating surface. The enhancement of CHF can increase the safety margins and allow operation at higher heat fluxes; thus, it can increase the economy. A very interesting characteristics of nano-fluids is their ability to significantly enhance the CHF. nano-fluids are nano-technology-based colloidal dispersions engineered through stable suspending of nanoparticles. All experiments were performed in round tubes with an inner diameter of 0.01041 m and a length of 0.5 m under low pressure and low flow (LPLF) conditions at a fixed inlet temperature using water, 0.01 vol. % Al2O3/water and SiC/water nano-fluids. It was found that the CHF of the nano-fluids was enhanced and the CHF of the SiC/water nano-fluid was more enhanced than that of the Al2O3/water nano-fluid. (authors)

  14. Study on critical heat flux enhancement in flow boiling of SiC nano-fluids under low pressure and low flow conditions

    Lee, S. W.; Park, S. D.; Kang, S.; Kim, S. M.; Seo, H. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City, 689-798 (Korea, Republic of); Lee, D. W. [Korea Atomic Energy Research Inst. (KAERI), Deokjin-dong, Yuseong-gu, Daejeon, 305-600 (Korea, Republic of); Bang, I. C. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City, 689-798 (Korea, Republic of)

    2012-07-01

    Critical heat flux (CHF) is the thermal limit of a phenomenon in which a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the heat transfer efficiency, thus causing localized overheating of the heating surface. The enhancement of CHF can increase the safety margins and allow operation at higher heat fluxes; thus, it can increase the economy. A very interesting characteristics of nano-fluids is their ability to significantly enhance the CHF. nano-fluids are nano-technology-based colloidal dispersions engineered through stable suspending of nanoparticles. All experiments were performed in round tubes with an inner diameter of 0.01041 m and a length of 0.5 m under low pressure and low flow (LPLF) conditions at a fixed inlet temperature using water, 0.01 vol. % Al{sub 2}O{sub 3}/water and SiC/water nano-fluids. It was found that the CHF of the nano-fluids was enhanced and the CHF of the SiC/water nano-fluid was more enhanced than that of the Al{sub 2}O{sub 3}/water nano-fluid. (authors)

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

    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.

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

    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

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

    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.

  18. An experimental study of relative permeability hysteresis, capillary trapping characteristics, and capillary pressure of CO2/brine systems at reservoir conditions

    Austin Suthanthiraraj, Pearlson Prashanth

    We present the results of an extensive experimental study on the effects of hysteresis on permanent capillary trapping and relative permeability of CO2/brine and supercritical (sc)CO2+SO2/brine systems. We performed numerous unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, i.e., low and high-permeability Berea, Nugget sandstones, and Madison limestone carbonate rock sample. A state-of-the-art reservoir conditions core-flooding system was used to perform the tests. The core-flooding apparatus included a medical CT scanner to measure in-situ saturations. The scanner was rotated to the horizontal orientation allowing flow tests through vertically-placed core samples with about 3.8 cm diameter and 15 cm length. Both scCO2 /brine and gaseous CO2 (gCO2)/brine fluid systems were studied. The gaseous and supercritical CO2/brine experiments were carried out at 3.46 and 11 MPa back pressures and 20 and 55°C temperatures, respectively. Under the above-mentioned conditions, the gCO2 and scCO2 have 0.081 and 0.393 gr/cm3 densities, respectively. During unsteady-state tests, the samples were first saturated with brine and then flooded with CO2 (drainage) at different maximum flow rates. The drainage process was then followed by a low flow rate (0.375 cm 3/min) imbibition until residual CO2 saturation was achieved. Wide flow rate ranges of 0.25 to 20 cm3/min for scCO2 and 0.125 to 120 cm3min for gCO2 were used to investigate the variation of initial brine saturation (Swi) with maximum CO2 flow rate and variation of trapped CO2 saturation (SCO2r) with Swi. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO 2. During the steady-state experiments, after providing of fully-brine saturated core, scCO2 was injected along with brine to find the drainage curve and as

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

    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

  20. Effects of pressure and temperature at deformation in conditions of uniform compression on physical-mechanical properties of titanium in the range of 77...800 K

    Influence of deformation at 25% under uniform compression at pressure of 22 and 16.5 kbar at 77 K and 12 and 8 kbar at 300 K by using quasi hydroextrusion with counter pressure (QHEC) and without counter pressure (QHE) on physical-mechanical properties of titanium VT1-0 in the range of 77...800 K was investigated. It was shown, that two-stage character of dependence mechanical properties versus temperature in initial state (temperature-dependent in the range of 77...600 K and athermal in the range of 600...800 K) after deformation QHE and QHEP changed to one-stage and temperature-dependent character in the entire temperature range. It was shown that deformation under uniform pressure result in increase of strength in the range of 77...800 K and decrease the stacking fault energy of titanium. That is an addition factor of hardening besides increasing the density of deformation defects. It was found that uniform compression realized under higher pressures leads to less hardening and less accumulation of deformation defects. This associated with activation of recovery processes

  1. Electrical resistivity of YbRh2Si2 and EuT2Ge2 (T=Co,Cu) at extreme conditions of pressure and temperature

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical-resistivity measurements, ρ(T), from room temperature down to 100 mK. (orig.)

  2. Thermal-hydraulic instability of the natural circulation BWR. 6. Occurrence condition and mechanism of the instability at the higher system pressure

    Experiments have been conducted to investigate thermal-hydraulic instabilities at the higher system pressure ranging from 1.0 to 7.2 MPa in a boiling natural circulation loop with a chimney. A test facility used in this experiments was designed and constructed to have non-dimensional values which are nearly equal to those of natural circulation BWR flow dynamics. Stability maps in reference to the system pressure, the channel inlet subcooling, and heat flux are presented. This instability mechanism is classified into the density wave oscillations that oscillation period is one to two times the time required for a bubble generated in the channel to travel through the chimney, and different from the flashing induced instability at the lower system pressure. The difference from other phenomena such as flow pattern transient oscillations and natural circulation oscillations are discussed by investigating the transient flow pattern and the response of momentum energy to driving force of the circulation. (author)

  3. 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

    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。

  4. Experience of HP 'Termoelektro' in production of universal program for overhaul and following the condition of high pressure steam pipes, with special turn on TPP 'Oslomej' Kichevo - Macedonia

    In this paper an universal programme for revitalization of the high pressure steam lines in power plants is developed. All this aimed toward providing maximal working cycle continuation as well as better reliability and safety in the exploitation regime. In addition a special turn on the overhaul of the main steam lines and feedwater pipeline at Thermal Power Plant 'Oslomej' (Macedonia) is presented

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

    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 ...

  6. Biogas barometer; Le barometre biogaz

    NONE

    2006-12-15

    This annual evaluation is a synthesis of works published in 2006. Comparisons are presented between the wind power performances and European Commission White Paper and Biomass action plan objectives. The United Kingdom is the leading european country in terms of production, but is being challenged more and more by Germany, which markedly increased its production in 2005. France is only classed 5. in Europe in spite of a valorisable potential. (A.L.B.)

  7. Blood pressure

    ... 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 ...

  8. Breeding pond selection and movement patterns by eastern spadefoot toads (Scaphiopus holbrookii) in relation to weather and edaphic conditions.

    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

  9. Volume-translated cubic EoS and PC-SAFT density models and a free volume-based viscosity model for hydrocarbons at extreme temperature and pressure conditions

    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.

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

    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.

  11. 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.

    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 < 0.001). There were no significant differences in cortisol level between the two groups. The results suggest the need for further study into other possible physiological effects on stress of TTM. PMID:27210845

  12. Territorial characterisation considering geo morphological properties of subsoil as well as climatic and meteorological conditions for the evaluation of the effects of radiological nature on the environment

    The composition and origin of the rocky substratum, the permeability of the ground, its degree of humidity and the particle size are the main factors that influence radon concentration in the subsoil and in the water stratums as well as its upward migration. The climatic and meteorological conditions, particularly the moisture, the barometric pressure and the temperature, can influence more or less directly the underground emanation and diffusion properties of radon and thoron giving rise to short-term modifications of radiological nature in the subsoil, closely related to the presence of these elements. The great concentration of some radioisotopes, in some particular areas, can also induce high dose rates caused by the radiation coming from emergent rocks, due for instance to activities related to building works, with consequent possible exposure of the personnel involved in underground excavations. In such situations it is possible to carry out systematical radiometric measurements, which provide instantaneous and time integrated data, using fixed or movable instrumentation. The stratigraphical structure of the subsoil and the related variations of lithological nature as well as the lack of homogeneity in the land, due also to the unevenness of the ground outline and to the presence of fault planes, increase considerably the complexity of analytical evaluations based upon the chemical and physical characteristics of the subsoil and upon the meteorological and climatic properties

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

    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,…

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

    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...

  15. 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

    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.

  16. 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

    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

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

    Periotto, Benedetta

    applications also in the materials science as it can provide useful information about the properties and performance of new materials. Over the past decades, the research in this field has been strongly developed due to the advances in computer capabilities and to the technological improvements of X...... started with a comparison between two different DACs, in order to define the capabilities of one of the most common types of pressure device, the ETH-type DAC. Application examples of data quality analysis have been conducted on pyroxenes (NaInSi2O6, orthoenstatite MgSiO3 and LiCrSi2O6), which are...

  18. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity

    A nonlinear stability threshold for rotation in a couple-stress fluid heated from below saturating a porous medium with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. The effects of couple-stress parameter, variable dependent viscosity, medium permeability, Taylor number and Darcy–Brinkman number on the onset of convection are also analysed. (paper)

  19. Development of an autoclave with zirconia crystal windows for in-situ observation of sample surface under primary water conditions of pressurized water reactors

    Elucidating the mechanism for primary water stress corrosion cracking (PWSCC) is important for improving the reliability of structural materials in the primary system of pressurized water reactors (PWR). For this purpose, visualization of corrosion material surface in the primary coolant environment is effective, but it was impossible because of lack of suitable window material. Yttria stabilized zirconia was newly selected as a candidate for in-situ window material in the primary coolant environment of PWR. Its sufficient corrosion resistance was proved by measuring the transmissivity of light after being immersed in the primary coolant environment. A new autoclave with two windows of yttria-stabilized zirconia was developed. The corrosion material surfaces of Alloy600 and SUS304 in the primary coolant environment were clearly observed with this autoclave. Observations of cracks generated on the surface of SUS304 specimen, suggest that its generation time depends on temperature. (author)

  20. Design of an R.F. Excited Helium Neon Visible Gas Laser and Study of the Optimal Conditions for Gas Mixtures and Pressures

    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.`

  1. Effects of weather conditions on emergency ambulance calls for acute coronary syndromes.

    Vencloviene, Jone; Babarskiene, Ruta; Dobozinskas, Paulius; Siurkaite, Viktorija

    2015-08-01

    The aim of this study was to evaluate the relationship between weather conditions and daily emergency ambulance calls for acute coronary syndromes (ACS). The study included data on 3631 patients who called the ambulance for chest pain and were admitted to the department of cardiology as patients with ACS. We investigated the effect of daily air temperature (T), barometric pressure (BP), relative humidity, and wind speed (WS) to detect the risk areas for low and high daily volume (DV) of emergency calls. We used the classification and regression tree method as well as cluster analysis. The clusters were created by applying the k-means cluster algorithm using the standardized daily weather variables. The analysis was performed separately during cold (October-April) and warm (May-September) seasons. During the cold period, the greatest DV was observed on days of low T during the 3-day sequence, on cold and windy days, and on days of low BP and high WS during the 3-day sequence; low DV was associated with high BP and decreased WS on the previous day. During June-September, a lower DV was associated with low BP, windless days, and high BP and low WS during the 3-day sequence. During the warm period, the greatest DV was associated with increased BP and changing WS during the 3-day sequence. These results suggest that daily T, BP, and WS on the day of the ambulance call and on the two previous days may be prognostic variables for the risk of ACS. PMID:25344902

  2. Effects of weather conditions on emergency ambulance calls for acute coronary syndromes

    Vencloviene, Jone; Babarskiene, Ruta; Dobozinskas, Paulius; Siurkaite, Viktorija

    2015-08-01

    The aim of this study was to evaluate the relationship between weather conditions and daily emergency ambulance calls for acute coronary syndromes (ACS). The study included data on 3631 patients who called the ambulance for chest pain and were admitted to the department of cardiology as patients with ACS. We investigated the effect of daily air temperature ( T), barometric pressure (BP), relative humidity, and wind speed (WS) to detect the risk areas for low and high daily volume (DV) of emergency calls. We used the classification and regression tree method as well as cluster analysis. The clusters were created by applying the k-means cluster algorithm using the standardized daily weather variables. The analysis was performed separately during cold (October-April) and warm (May-September) seasons. During the cold period, the greatest DV was observed on days of low T during the 3-day sequence, on cold and windy days, and on days of low BP and high WS during the 3-day sequence; low DV was associated with high BP and decreased WS on the previous day. During June-September, a lower DV was associated with low BP, windless days, and high BP and low WS during the 3-day sequence. During the warm period, the greatest DV was associated with increased BP and changing WS during the 3-day sequence. These results suggest that daily T, BP, and WS on the day of the ambulance call and on the two previous days may be prognostic variables for the risk of ACS.

  3. 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

    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.

  4. An investigation of the heat transfer and static pressure on the over-tip casing wall of an axial turbine operating at engine representative flow conditions. (I). Time-mean results

    Thorpe, S.J.; Yoshino, S.; Ainsworth, R.W.; Harvey, N.W

    2004-12-01

    The over-tip casing of the high-pressure turbine in a modern gas turbine engine is subjected to strong convective heat transfer that can lead to thermally induced failure (burnout) of this component. However, the complicated flow physics in this region is dominated by the close proximity of the moving turbine blades, which gives rise to significant temporal variations at the blade-passing frequency. The understanding of the physical processes that control the casing metal temperature is still limited and this fact has significant implications for the turbine design strategy. A series of experiments has been performed that seeks to address some of these important issues. This article reports the measurements of time-mean heat transfer and time-mean static pressure that have been made on the over-tip casing of a transonic axial-flow turbine operating at flow conditions that are representative of those found in modern gas turbine engines. Time-resolved measurements of these flow variables (that reveal the details of the blade-tip/casing interaction physics) are presented in a companion paper. The nozzle guide vane exit flow conditions in these experiments were a Mach number of 0.93 and a Reynolds number of 2.7 x 10{sup 6} based on nozzle guide vane mid-height axial chord. The axial and circumferential distributions of heat transfer rate, adiabatic wall temperature, Nusselt number and static pressure are presented. The data reveal large axial variations in the wall heat flux and adiabatic wall temperature that are shown to be primarily associated with the reduction in flow stagnation temperature through the blade row. The heat flux falls by a factor of 6 (from 120 to 20 kW/m{sup 2}). In contrast, the Nusselt number falls by just 36% between the rotor inlet plane and 80% rotor axial chord; additionally, this drop is near to linear from 20% to 80% rotor axial chord. The circumferential variations in heat transfer rate are small, implying that the nozzle guide vanes do

  5. An investigation of the heat transfer and static pressure on the over-tip casing wall of an axial turbine operating at engine representative flow conditions. 1. Time-mean results

    Thorpe, S.J.; Ainsworth, R.W. [University of Oxford (United Kingdom). Dept. of Engineering Science; Yoshino, S. [Tokyo Electric Power Co., Yokohama (Japan). Thermal Power Technology Group; Harvey, N.W. [Rolls-Royce plc., Turbine Systems, Derby (United Kingdom)

    2004-12-01

    The over-tip casing of the high-pressure turbine in a modern gas turbine engine is subjected to strong convective heat transfer that can lead to thermally induced failure (burnout) of this component. However, the complicated flow physics in this region is dominated by the close proximity of the moving turbine blades, which gives rise to significant temporal variations at the blade-passing frequency. The understanding of the physical processes that control the casing metal temperature is still limited and this fact has significant implications for the turbine design strategy. A series of experiments has been performed that seeks to address some of these important issues. This article reports the measurements of time-mean heat transfer and time-mean static pressure that have been made on the over-tip casing of a transonic axial-flow turbine operating at flow conditions that are representative of those found in modern gas turbine engines. Time-resolved measurements of these flow variables (that reveal the details of the blade-tip/casing interaction physics) are presented in a companion paper. The nozzle guide vane exit flow conditions in these experiments were a Mach number of 0.93 and a Reynolds number of 2.7 x 10{sup 6} based on nozzle guide vane mid-height axial chord. The axial and circumferential distributions of heat transfer rate, adiabatic wall temperature, Nusselt number and static pressure are presented. The data reveal large axial variations in the wall heat flux and adiabatic wall temperature that are shown to be primarily associated with the reduction in flow stagnation temperature through the blade row. The heat flux falls by a factor of 6 (from 120 to 20 kW/m{sup 2}). In contrast, the Nusselt number falls by just 36% between the rotor inlet plane and 80% rotor axial chord; additionally, this drop is near to linear from 20% to 80% rotor axial chord. The circumferential variations in heat transfer rate are small, implying that the nozzle guide vanes do

  6. Micro-Pressure Sensors for Future Mars Missions

    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.

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

    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

  8. Smoluchowski Equations for Agglomeration in Conditions of Variable Temperature and Pressure and a New Scaling of Rate Constants: Application to Nozzle-Beam Expansion.

    Chaiken, J; Goodisman, J; Kornilov, O

    2015-07-01

    The Smoluchowski equations provide a rigorous and efficient means for including multiple kinetic pathways when modeling coalescence growth systems. Originally written for a constant temperature and volume system, the equations must be modified if temperature and pressure vary during the coalescence time. In this paper, the equations are generalized, and adaptations appropriate to the situation presented by supersonic nozzle beam expansions are described. Given rate constants for all the cluster-cluster reactions, solution of the Smoluchowski equations would yield the abundances of clusters of all sizes at all times. This is unlikely, but we show that if these rate constants scale with the sizes of the reacting partners, the asymptotic (large size and large time) form of the cluster size distribution can be predicted. Experimentally determined distributions for He fit the predicted asymptotic distribution very well. Deviations between predicted and observed distributions allow identification of special cluster sizes that is, magic numbers. Furthermore, fitting an observed distribution to the theoretical form yields the base agglomeration cross section, from which all cluster-cluster rate constants may be obtained by scaling. Comparing the base cross section to measures of size and reactivity gives information about the coalescence process. PMID:26067086

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

    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

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

    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

  11. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    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.

  12. 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

    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.

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

    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

  14. Study on flow induced vibration evaluation for a large scale JSFR piping. (3) Pressure fluctuation characteristics in 1/3 scale hot-leg piping experiments under deflected inflow conditions due to UIS structures

    In this study, flow-induced vibration experiments were performed using a test facility that simulates the hot-leg (HL) piping with a 1/3-scale model to investigate flow patterns and fluctuating pressures on the pipe wall. The complicated flow in the upper plenum of the reactor vessel goes into the HL piping. One of the flows entering the HL which could significantly influence a flow-induced vibration is deflected flow. This paper describes the 1/3-scale experimental results under the deflected-flow conditions at the inlet of the HL. To simulate the flow conditions, a part of an upper internal structure was modeled in the test facility to generate deflected flow. The parameters were an intensity of deflected flow controlled by the opening ratio of the no.1 baffle plate of the upper internal structure. Quantitative investigation was conducted in terms of the influence of the deflected flow on the size of the flow separation, the flow velocity distribution, and intensity of fluctuating pressure on the pipe wall. It could be observed that the region of the flow separation was deformed by the deflect flow. In the case of the 0% opening, the tendency of the velocity distribution near the flow separation and the shape of flow separation differ from those in the other cases of opening. (author)

  15. 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

    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

  16. Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning

    With growing industrialization in power sector, air is being polluted with a host of substances-most conspicuously with suspended particulate matter emanating from coal-fired thermal power plants. Flue gas conditioning, especially in such power plants, requires in situ generation of ammonia. In the present paper, experiments for kinetic study of hydrolysis of urea have been conducted using a borosil glass reactor, first without stirring followed by with stirring. The study reveals that conversion increases exponentially with an increase in temperature and feed concentration. Furthermore, the effect of stirring speed, temperature and concentration on conversion has been studied. Using collision theory, temperature dependency of forward rate constant has been developed from which activation energy of the reaction and the frequency factors have been calculated. It has been observed that the forward rate constant increases with an increase in temperature. The activation energy and frequency factor with stirring has been found to be 59.85 kJ/mol and 3.9 x 106 min-1 respectively with correlation co-efficient and standard deviation being 0.98% and ±0.1% in that order.

  17. Measurement of endolymphatic pressure.

    Mom, T; Pavier, Y; Giraudet, F; Gilain, L; Avan, P

    2015-04-01

    Endolymphatic pressure measurement is of interest both to researchers in the physiology and pathophysiology of hearing and ENT physicians dealing with Menière's disease or similar conditions. It is generally agreed that endolymphatic hydrops is associated with Menière's disease and is accompanied by increased hydrostatic pressure. Endolymphatic pressure, however, cannot be measured precisely without endangering hearing, making the association between hydrops and increased endolymphatic pressure difficult to demonstrate. Several integrated in vivo models have been developed since the 1960s, but only a few allow measurement of endolymphatic hydrostatic pressure. Models associating measurement of hydrostatic pressure and endolymphatic potential and assessment of cochlear function are of value to elucidate the pathophysiology of endolymphatic hydrops. The present article presents the main types of models and discusses their respective interest. PMID:25467202

  18. Management of the coastal biophysical environment in tropical Queensland under conditions of heavy developmental pressure: the case of tourist resorts and acid sulphate soils

    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.

  19. Pressure locking test results

    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. Pressure Sores

    ... pressure sore include the following: Thick yellow or green pus A bad smell from the sore Redness ... spots, color changes or other signs of sores. Pay special attention to the pressure points where sores ...

  1. Pressure ulcers.

    O'Byrne, Deborah

    2016-04-13

    My nursing experience is in acute care. Acute medical nurses are well placed to assess skin integrity, identify patients at risk of pressure ulcer development, and commence appropriate interventions to prevent or treat pressure ulcers. PMID:27073966

  2. Peer Pressure

    ... 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 ...

  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

    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

    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

    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. Carbon dioxide, temperature, salinity, and barometric pressure collected via surface underway survey from R/V McArthur II in the eastern North and South Pacific from July 30, 2006 to July 26, 2007 (NODC Accession 0084052)

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

  7. Behavior of low alloy steel SA-508 and carbon steel A-410b in operation and shutdown conditions in primary loop of pressurized water reactor (PWR); Comportamiento del acero de baja aleacion SA-508 y del acero al carbono A-410b en las condiciones de operacion y parada del circuito primario de los reactores de agua ligera tipo PWR

    Garcia-Redondo, M. S.; Castano-Marin, M. L.; Gomez-Briceno, D. [Ciemat. Madrid (Spain)

    2000-07-01

    The corrosion rate of low alloy steel SA-508 and carbon steel A-410b in simulated operation and shutdown conditions of pressurized water reactor has been determined Moreover potentiodynamic polarization curves and galvanic effect through coupling of AISI-304 have been carried out under shutdown simulated condition. (Author) 8 refs.

  8. 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

    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.

  9. [Individual pressure tolerance--a "target" pressure?].

    Bogdănici, C; Vancea, P P

    1999-01-01

    In literature there are many meanings for the limit between normal and pathological intraocular pressure: "normative pressure", "critic pressure", "individual tolerance pressure" and "target pressure". The aim of this paper is to demonstrate that these terms are synonymous. PMID:10756882

  10. Critical CRBR core pressure

    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

  11. Pressure Drop

    Lawson, Mike

    2010-01-01

    Mike Lawson briefly discussed pressure drop for aerospace applications and presented short stories about adventures experienced while working at NASA and General Dynamics, including exposure to technologies like the Crew and Equipment Translation Aid (CETA) cart and the SWME.

  12. Pressure sensor

    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.

  13. Experimental research on pressure loss of rotary pressure exchanger

    Jiao, L.; Shi, Y.; Liu, Z. C.; Li, L.; Feng, Z. M.; Zhao, C. F.; Wei, Y.

    2016-05-01

    In order to research the phenomenon ‘Pressure Loss’ of Rotary Pressure Exchanger when it worked in a certain working condition, such as pressure and flow, two different series of experiments were performed respectively in the same experimental apparatus. One is to set pressure as constant when flow is changeable, the other one is to set flow as constant when pressure is changeable. Then, the curves and tables depicting the relationship between the pressure loss rate and working conditions were illustrated. Results from the curves and tables show that flow and pressure has an impact on pressure loss, and the relationship present some of regularity. According to the regularity, an empirical formula which can be used to approximately predict the magnitude of pressure loss for subsequent engineering application was provided by regression analysis on the basis of experimental data. Meanwhile, a 3-Dimensional geometric model of passageway in rotary pressure exchanger were built to verify the accuracy, making a steady calculation on pressure field by Fluent. At last, the feasibility was verified in a field application in a desalination factory.

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

    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

  15. Pressure sensors for petroleum wells

    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

  16. An investigation of the heat transfer and static pressure on the over-tip casing wall of an axial turbine operating at engine representative flow conditions. (II). Time-resolved results

    This article reports the measurements of time-resolved heat transfer rate and time-resolved static pressure that have been made on the over-tip casing of a transonic axial-flow turbine operating at flow conditions that are representative of those found in modern gas turbine engines. This data is discussed and analysed in the context of explaining the physical mechanisms that influence the casing heat flux. The physical size of the measurement domain was one nozzle guide vane-pitch and from -20% to +80% rotor axial chord. Additionally, measurements of the time-resolved adiabatic wall temperature are presented. The time-mean data from the same set of experiments is presented and discussed in Part I of this article. The nozzle guide vane exit flow conditions in these experiments were a Mach number of 0.93 and a Reynolds number of 2.7 x 106 based on nozzle guide vane mid-height axial chord. The data reveal large temporal variations in heat transfer characteristics to the casing wall that are associated with blade-tip passing events and in particular the blade over-tip leakage flow. The highest instantaneous heat flux to the casing wall occurs within the blade-tip gap, and this has been found to be caused by a combination of increasing flow temperature and heat transfer coefficient. The time-resolved static pressure measurements have enabled a detailed understanding of the tip-leakage aerodynamics to be established, and the physical mechanisms influencing the casing heat load have been determined. In particular, this has focused on the role of the unsteady blade lift distribution that is produced by upstream vane effects. This has been seen to modulate the tip-leakage flow and cause subsequent variations in casing heat flux. The novel experimental techniques employed in these experiments have allowed the measurement of the time-resolved adiabatic wall temperature on the casing wall. These data clearly show the falling flow temperatures as work is extracted from the gas

  17. 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

    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

  18. 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

    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

  19. Chemical pressure

    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.

  20. Reactor pressure boundary materials

    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

  1. Pressurized hopper

    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

  2. The cystogram under pressure

    Full text: The direct radionuclide cystogram (DRC) is a sensitive test for the detection of vesico-ureteric reflux (VUR), but has no recognized grading system. The X-ray micturating cystourethrogram (MCU) has an international grading system based on the calibre of the urinary system and the level of reflux reached. While reflux grades of 4 and 5 are more serious, the condition may resolve spontaneously with maturation almost irrespective of the grade. A functional grading system of the DRC has been applied for 14 years in our hospital. It is considered that reflux first occurring at low bladder volume/pressure presents a greater risk of renal insult, as reflux will occur more often. Conversely, the higher pressure grades may predict reflux that is progressing towards natural resolution. Results of 82 reflux infants first investigated under the age of 1 year (average age 0.42 years) with serial cystograms (average age 1.5 years) indicates that low pressure reflux resolves at 42%, moderate pressure 78%, high 92% and voiding grades 67%. Dual cystograms (MCU and DRC) on 62 of these infants at the same setting detected a total of 104 units of reflux, the MCU detecting only 48 and the DRC 96 units (sensitivity 46% and 92% respectively). In addition, low pressure reflux reflected a higher risk of renal insult with 44% renal dimercaptosuccinic acid (DMSA) scans reported with defects against an overall DMSA rate from all grades of 33%. The DRC volume/pressure grading offers a functional assessment with predictive value. In the young infant it would appear that the MCU has poor sensitivity for the detection of reflux and that it is the technique 'under pressure' from the direct radionuclide alternative

  3. Blood Pressure Quiz

    ... 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 ...

  4. Hypertension (High Blood Pressure)

    ... 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 ...

  5. Blood pressure measurement

    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 ...

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

    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.

  7. 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

    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.)

  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

    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. Bulkhead pressure measurements in model fill pours

    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.

  10. Peculiar magnetic properties of Er conditioned Ni.sub.43./sub.Co.sub.7./sub.Mn.sub.31./sub.Ga.sub.19./sub. at ambientand hydrostatic pressures

    Kaštil, J.; Kamarád, Jiří; Knížek, Karel; Arnold, Zdeněk; Javorský, P.

    2013-01-01

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

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

    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....

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

    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...

  13. First evidence of P2{sub 1}/n to P2{sub 1}/c structural transformation in pyroxene-type LiAlGe{sub 2}O{sub 6} under high-pressure conditions

    Nestola, Fabrizio, E-mail: fabrizio.nestola@unipd.it [Department of Geosciences, University of Padua, Via Gradenigo 6, I-35131 Padova (Italy); Artac, Andreas; Pippinger, Thomas; Miletich, Ronald [Institut für Mineralogie und Kristallographie, Universität Wien, Althanstrasse 14, A-1090 Wien (Austria); Secco, Luciano; Milani, Sula [Department of Geosciences, University of Padua, Via Gradenigo 6, I-35131 Padova (Italy); Redhammer, Günther J. [Fachbereich Materialforschung und Physik, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg (Austria)

    2015-08-15

    The high-pressure behavior of the pyroxene-type compound LiAlGe{sub 2}O{sub 6}, the unique representative of a P2{sub 1}/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/V{sub 0}=−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 K{sub 0}=114(1) and 123(2) GPa, respectively, as described by a 2{sup nd} order Birch–Murnaghan equation of state. Based on the systematic extinctions the transition was identified as a P2{sub 1}/n-to-P2{sub 1}/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 Ge{sub 2}O{sub 6}-chains, which explains the anisotropy of axial elasticities and the spontaneous strain across the transformation. Simultaneously the distortion correction of AlO{sub 6} units associated with the transition further explains the preference of the P2{sub 1}/c structure under pressure. - Graphical abstract: Detail of the crystal structures of LP-LAG at 3.48 GPa (left) and HP-LAG at 4.51 GPa (right). Li on M2 are green; AlO{sub 6} octahedra (Al at M1) are orange; tetrahedra sites in LP-LAG: T1 (yellow) and T2 (blue); tetrahedra sites in HP-LAG: A-chains (yellow), B-chains (blue). - Highlights: • A new high-pressure phase transition P2{sub 1}/n–P2{sub 1}/c was found for LaAlGe{sub 2}O{sub 6}. • The transition was also followed by micro-Raman spectroscopy. • The high-pressure polymorph shows a higher bulk modulus. • The structural

  14. Pressure transient in liquid lines

    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. Optimization of compound pressure cylinders

    G.H. Majzoobi; A. Ghomi

    2006-01-01

    Purpose: The purpose of this paper is optimization of the weight of compound cylinder for a specific pressure. The variables are shrinkage radius and shrinkage tolerance.Design/methodology/approach: SEQ technique for optimization, the finite element code, ANSYS for numerical simulation are employed to predict the optimized conditions. The results are verified by testing a number of closed end cylinders with various geometries, materials and internal pressures.Findings: The weight of a compoun...

  16. Ultrahigh vacuum/high-pressure flow reactor for surface x-ray diffraction and grazing incidence small angle x-ray scattering studies close to conditions for industrial catalysis

    A versatile instrument for the in situ study of catalyst surfaces by surface x-ray diffraction and grazing incidence small angle x-ray scattering in a 13 ml flow reactor combined with reaction product analysis by mass spectrometry has been developed. The instrument bridges the so-called ''pressure gap'' and ''materials gap'' at the same time, within one experimental setup. It allows for the preparation and study of catalytically active single crystal surfaces and is also equipped with an evaporator for the deposition of thin, pure metal films, necessary for the formation of small metal particles on oxide supports. Reactions can be studied in flow mode and batch mode in a pressure range of 100-1200 mbar and temperatures up to 950 K. The setup provides a unique combination of sample preparation, characterization, and in situ experiments where the structure and reactivity of both single crystals and supported nanoparticles can be simultaneously determined.

  17. 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

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

    2015-01-01

    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 fr...

  18. High Blood Pressure (Hypertension)

    ... 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 ...

  19. Understanding Blood Pressure Readings

    ... 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 ...

  20. High Blood Pressure

    ... Connected Home » High Blood Pressure Heath and Aging High Blood Pressure What Is Blood Pressure? Do ... high blood pressure increases as you get older. Gender. Before age 55, men have a greater chance ...

  1. High Blood Pressure

    ... 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 ...

  2. Bedsores (Pressure Ulcers)

    ... and rashes clinical tools newsletter | contact Share | Bedsores (Pressure Ulcers) Information for adults A A A A well-defined superficial pressure ulcer. Overview Bedsores (pressure ulcers), also known as pressure ...

  3. 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

    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.

  4. Prediction of pressure tube ballooning under non-uniform circumferential temperature gradients and high internal pressure

    In some accident scenarios in CANDU reactors the pressure tube is expected to reach sufficiently high temperature at high internal pressure such that the pressure tube expands radially, i.e., the pressure tube balloons.Under these conditions it is of importance to the assessment of fuel channel integrity to be able to accurately predict the timing and extent of pressure tube ballooning. If the circumferential temperature gradient on the pressure tube is non-uniform, the resulting transverse hoop stress is non-uniform and the pressure tube experiences a non-uniform ballooning. This could result in a failure of the pressure tube before it balloons into contact with the surrounding calandria tube. The fuel channel integrity code SMARTT (Simulation Method for Azimuthal and Radial Temperature Transients) is used to predict the ballooning of CANDU Zr-2.5wt%Nb pressure tubes. The pressure tube strain rate calculation in SMARTT was extracted and used as the basis for the code PTSTRAIN which was constructed to model pressure tube ballooning with the temperature of the pressure tube and the internal pressure specified as the boundary conditions for the calculation. The main objectives of this paper are to describe the comparison of the predictions of this code against two different sets of experiments which were performed with defected and non-defected pressure tubes, and to provide further validation of the pressure tube ballooning model against independent experiments. (author)

  5. Chromosomal Conditions

    ... 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 ...

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

    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.

  7. Pressurized thermal shock (PTS)

    In the present work, a description of Thermal Shock in Pressurized conditions (PTS), and its influence in the treatment of the integrity of the pressure vessel (RPV) of a Pressurized Water Reactor (PWR) and/or of a Heavy water Pressurized water Reactor (PHWR) is made. Generally, the analysis of PTS involves a process of three stages: a-) Modeling with a System Code of relevant thermohydraulics transients in reference with the thermal shock; b-) The local distribution of temperatures in the downcomer and the heat transference coefficients from the RPV wall to the fluid, are determined; c-) The fracture mechanical analysis. These three stages are included in this work: Results with the thermohydraulics code Relap5/mod.3, are obtained, for a LOCA scenario in the hot leg of the cooling System of the Primary System of the CAN-I reactor. The method used in obtaining results is described. A study on the basis of lumped parameters of the local evolutions of the temperature of the flow is made, in the downcomer of the reactor pressure vessel. The purpose of this study is to determine how the intensification of the stress coefficient, varies in function of the emergency injected water during the thermohydraulic transients that take place under the imposed conditions in the postulated scene. Specially, it is considered a 50 cm2 break, located in the neighborhoods of the pressurized with the corresponding hot leg connection. This size is considered like the most critical. The method used to obtain the results is described. The fracture mechanical analysis is made. From the obtained results we confirmed that we have a simple tool of easy application in order to analyze phenomena of the type PTS in the postulated scenes by break in the cold and hot legs of the primary system. This methodology of calculus is completely independent of the used ones by the Nucleoelectrica Argentina S.A. (NASA) in the analysis of the PTS phenomena in the CAN-I. The results obtained with the adopted

  8. Pressure polymerization of polyester

    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.

  9. Oil point pressure of Indian almond kernels

    Aregbesola, O.; Olatunde, G.; Esuola, S.; Owolarafe, O.

    2012-07-01

    The effect of preprocessing conditions such as moisture content, heating temperature, heating time and particle size on oil point pressure of Indian almond kernel was investigated. Results showed that oil point pressure was significantly (P < 0.05) affected by above mentioned parameters. It was also observed that oil point pressure reduced with increase in heating temperature and heating time for both coarse and fine particles. Furthermore, an increase in moisture content resulted in increased oil point pressure for coarse particles while there was a reduction in oil point pressure with increase in moisture content for fine particles.

  10. 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

    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

  11. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated

  12. Medications and Blood Pressure

    ... 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 ...

  13. Fuel gas conditioning process

    Lokhandwala, Kaaeid A.

    2000-01-01

    A process for conditioning natural gas containing C.sub.3+ hydrocarbons and/or acid gas, so that it can be used as combustion fuel to run gas-powered equipment, including compressors, in the gas field or the gas processing plant. Compared with prior art processes, the invention creates lesser quantities of low-pressure gas per unit volume of fuel gas produced. Optionally, the process can also produce an NGL product.

  14. 49 CFR 178.345-10 - Pressure relief.

    2010-10-01

    ... pressure relief valves. A secondary pressure relief system consisting of another pressure relief valve in... volume of liquid released not exceeding 1 L before the relief valve recloses to a leak-tight condition...) Each reclosing pressure relief valve must be constructed and installed in such a manner as to...

  15. Competitive Deprotonation and Superoxide [O2 (-•)] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions.

    Hassan, Isra; Pinto, Spencer; Weisbecker, Carl; Attygalle, Athula B

    2016-03-01

    Carboxamides bearing an N-H functionality are known to undergo deprotonation under negative-ion-generating mass spectrometric conditions. Herein, we report that N-H bearing carboxamides with acidities lower than that of the hydroperoxyl radical (HO-O(•)) preferentially form superoxide radical-anion (O2 (-•)) adducts, rather than deprotonate, when they are exposed to the glow discharge of a helium-plasma ionization source. For example, the spectra of N-alkylacetamides show peaks for superoxide radical-anion (O2 (-•)) adducts. Conversely, more acidic amides, such as N-alkyltrifluoroacetamides, preferentially undergo deprotonation under similar experimental conditions. Upon collisional activation, the O2 (-•) adducts of N-alkylacetamides either lose the neutral amide or the hydroperoxyl radical (HO-O(•)) to generate the superoxide radical-anion (m/z 32) or the deprotonated amide [m/z (M - H)(-)], respectively. For somewhat acidic carboxamides, the association between the two entities is weak. Thus, upon mildest collisional activation, the adduct dissociates to eject the superoxide anion. Superoxide-adduct formation results are useful for structure determination purposes because carboxamides devoid of a N-H functionality undergo neither deprotonation nor adduct formation under HePI conditions. Graphical Abstract ᅟ. PMID:26545766

  16. Competitive Deprotonation and Superoxide [O2 -•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

    Hassan, Isra; Pinto, Spencer; Weisbecker, Carl; Attygalle, Athula B.

    2016-03-01

    Carboxamides bearing an N-H functionality are known to undergo deprotonation under negative-ion-generating mass spectrometric conditions. Herein, we report that N-H bearing carboxamides with acidities lower than that of the hydroperoxyl radical (HO-O•) preferentially form superoxide radical-anion (O2 -•) adducts, rather than deprotonate, when they are exposed to the glow discharge of a helium-plasma ionization source. For example, the spectra of N-alkylacetamides show peaks for superoxide radical-anion (O2 -•) adducts. Conversely, more acidic amides, such as N-alkyltrifluoroacetamides, preferentially undergo deprotonation under similar experimental conditions. Upon collisional activation, the O2 -• adducts of N-alkylacetamides either lose the neutral amide or the hydroperoxyl radical (HO-O•) to generate the superoxide radical-anion ( m/z 32) or the deprotonated amide [ m/z (M - H)-], respectively. For somewhat acidic carboxamides, the association between the two entities is weak. Thus, upon mildest collisional activation, the adduct dissociates to eject the superoxide anion. Superoxide-adduct formation results are useful for structure determination purposes because carboxamides devoid of a N-H functionality undergo neither deprotonation nor adduct formation under HePI conditions.

  17. High Blood Pressure

    ... 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 ...

  18. High blood pressure - infants

    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 . ...

  19. High Blood Pressure Facts

    ... 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 ...

  20. Preventing pressure ulcers

    Pressure ulcers are also called bedsores, or pressure sores. They can form when your skin and soft tissue ... become damaged or die. When this happens, a pressure ulcer may form. You have a risk of developing ...